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HomeMy WebLinkAboutCC - Drainage Report Prepared For: Pollard North Subdivision No. 2 Brighton Development, Inc., Meridian, Idaho ACHD, and City of Meridian Storm Drainage Report SS\0 N A L Etc �oF� \CENS /'LF 16860 s� 8/5/25 o Q OF /N c. Y, Digitally signed by Lachlin Kinsella, P.E. Date: 2025.08.05 17:36:25 -06'00' Prepared By: Lachlin Kinsella, P.E. Project Manager KM Engineering, LLP 5725 North Discovery Way Boise, I D 83713 208.639.6939 Ikinsella@kmengllp.com Ian August 2025 Project No: 24-296 E N G I N E E R I N G TABLE OF CONTENTS Introduction ................................................................................................................................. 1 ProjectDescription ...................................................................................................................... 1 SiteDescription............................................................................................................................... 1 Scopeand Methods........................................................................................................................ 1 Existing Drainage Conditions .......................................................................................................... 1 Proposed Drainage Conditions and Analysis .................................................................................. 1 Inletand Gutter Capacities ............................................................................................................. 2 SeepageBeds.................................................................................................................................. 2 InfiltrationBasin.............................................................................................................................. 2 Summary......................................................................................................................................... 3 APPENDICES Appendix A - Figures Figure 1 - Vicinity Map Figure 2 - Post-Development Drainage Map Figure 3 - Storm Water Improvement Plans Appendix B - Tables Table 1 - Peak Flow Rates and Runoff Volumes Appendix C - Calculations Post-Development 25-year Calculations Post-Development 100-year Calculations Inlet and Gutter Capacities Seepage Bed Calculations Infiltration Basin Calculations Appendix D - Geotechnical Engineering Report & Groundwater Data Pollard Lane Realigment (MTI, 8/31/2016) Ground water monitoring mid-year report— Pollard Lane project (NRS, 11/11/2023) INTRODUCTION The purpose of this report is to show that the storm drainage facilities for the proposed Pollard North Subdivision No. 2 (Project) are designed to meet Ada County Highway District (ACHD), City of Meridian, and the water quality requirements of the Idaho Department of Environmental Quality (DEQ). This report has been prepared at the request of the developer, Brighton Development, Inc. PROJECT DESCRIPTION The project consists of the second phase of a residential subdivision that includes 95 single-family residential lots and 18 common lots. The proposed improvements to the site include roadways, sidewalks, lot grading, and site utilities. SITE DESCRIPTION The project site is located north of W. Waverton Dr. near the intersection of N. Levi Ave. in Meridian, Idaho. See Appendix A, Figure 1 for a vicinity map of the project. The proposed project area is 10.46 acres. SCOPE AND METHODS The stormwater system for the Project has been designed per the 2017 ACHD Stormwater Policy. The Rational Method is the standard method for small catchments and was used to calculate post-development peak runoff rates and runoff volumes. The Rational Method provided in the ACHD calculation sheets was used to calculate the storm water volumes and flow rates for this project (see Appendix C - Calculations). Flow rates and storm volumes were established for each basin for the 25-year and 100-year storms. Refer to Appendix B, Table 1 - Peak Flow Rates and Runoff Volumes, for a summary of flow rates and runoff volumes. Calculations for the seepage beds and drainage Swale were completed to verify capacity. EXISTING DRAINAGE CONDITIONS The pre-project watershed consists primarily of agricultural land that was previously irrigated through open channels and includes one drainage basin. The irrigation wastewater and stormwater runoff are currently being collected to the west of the Project site. PROPOSED DRAINAGE CONDITIONS AND ANALYSIS The proposed drainage system improvements consist of roadway inlets and gutters, sand and grease traps, manholes, seepage beds, and an infiltration basin. The post-development site was broken into fifteen (15) basins as shown in Appendix A, Figure 2 - Post-Development Drainage Map. For land use type and runoff coefficients (0.1 — open space, 0.95 — impervious, 0.50 — lots, 0.35 - playgrounds) for each basin, refer to ACHD calculations in Appendix C. Each basin was delineated according to the tributary area draining to each drainage structure or facility such as gutter, catch basin inlet, etc. For individual sub-basin peak flow calculations, in addition to combined sub-basin peak 1 flows used for downstream facility sizing and analysis, see Table 1 (Peak Flow Rates and Runoff Volumes). The proposed drainage basins include the front half of the lots and all the proposed roadways, curb and gutters, and sidewalks. Storm water runoff consists of overland sheet flow over short grass that is conveyed with curb and gutter to catch basin inlets. The storm water runoff is then conveyed from the catch basin inlets to the proposed seepage beds or drainage swale. INLET AND GUTTER CAPACITIES The catch basin inlets should be built per the details shown on the civil construction plans. There are a total of eleven (11) single inlets. Based on our calculations, all inlets will require a single sump grate inlet to intercept the flows. The gutter capacity of the proposed roadways was verified to ensure that overtopping of the curb would not occur in the 25-year and 100-year storm event (refer to Appendix C— Inlet and Gutter Capacities). SEEPAGE BEDS The Project includes eight (8) seepage beds (SB #1-8) that should be built per the details shown on the civil construction plans. Based on our calculations, the seepage beds are adequately sized to ensure that no ponding should occur on the surface and the volume required to retain the 100-year storm event are met. Once the sizes of the seepage beds were calculated, the times necessary for 90% of the 100-year storm events to be infiltrated into the ground were calculated at less than 48- hours for each of the seepage beds. The design infiltration rate at 8 in/hr was used in the calculations and is based on the recommended rate for poorly graded gravel sediments from the geotechnical report prepared by MTI. The calculations included with this report show the volumes that are required to be retained for the 100-year storm and the drain time through the bottom of the seepage beds. Refer to Appendix B, Tables and Appendix C, Seepage Bed Calculations. INFILTRATION BASIN The infiltration basin (Pond #1) should be built per the details shown on the civil construction plans. The pond should be adequately sized to ensure that no ponding occurs on the surface and to retain the 100-year, 1-hour storm event volume. Since the bottom of the pond is less than 1,500sf, a forebay isn't included with the design. Once the size of the infiltrate basin was calculated,the time necessary for 90%of the 100- year storm events to be infiltrated into the ground was calculated at less than the 48-hour requirement. The design infiltration rate at 8 in/hr was used in the calculations and is based on the testing results from the geotechnical report prepared by Atlas. 2 The calculations included with this report show the volume that is required to be retained for the 100-year storm and the drain time through the bottom of the infiltration basin, Refer to Appendix B, Tables and Appendix C, Infiltration Basin Calculations. SUMMARY This report determines that the Project storm water design sizing and analysis should conform to ACHD and the water quality requirements of the Idaho Department of Environmental Quality (DEQ). The post-development storm water runoff for half of the proposed residential lots and the entire roadway, curb and gutters, and sidewalks should be completely retained onsite through the proposed seepage beds and drainage swale. 3 APPENDIX A - FIGURES �� PROJECT w a W J Z W.CHINDEN BLVD. a x ui 00 0 m U a O a O 0 g w z Z Y Z 2 U 5 3 Z v N 0 1000 2000 3000 a N N Plan Scale: 1" = 1000' z E N G I N E E R I N G G 5725 NORTH DISCOVERY WAY se X PHOINESE(08)639-6939 POLLARD NORTH SUBDIVISION NO. 2 o kmengllp.com MERIDIAN, ID a � DATE: AUGUST2025 > PROJECT: 24-296 N SHEET: VICINITY MAP EX1.0 a DRAINAGE LEGEND DESIGN POINTS 0 A BASIN DESIGNATION 1. INLET #1 1 2. INLET #2 2.5 AREA IN ACRES 3. INLET #3 0 60 120 180 4. INLET #4 Plan Scale: 1" = 60' DESIGN POINT 5. INLET #5 6. INLET #6 EXISTING GRADE CONTOUR 7. INLET #7 8. INLET #8 2470- 9. INLET #9 10. INLET #10 11. INLET #11 FINISHED GRADE CONTOUR 12. SGT #1 --2470 13. SGT #2 14. SGT #3 15. SGT #4 16. SGT #5 17. SGT #6 18. SEEPAGE BED #1 19. SEEPAGE BED #2 20. SEEPAGE BED #3 � 21. SEEPAGE BED #4 0 22. SEEPAGE BED #5 23. SEEPAGE BED #6 24. SEEPAGE BED #7 25. SEEPAGE BED #8 26. INFILTRATION BASIN POND #1 N Z O w - - - - - I P- - - r - - -EP- - - P P-�� E ZP- - - - - EP EP-____EP- EP EP EP EP EP EP EP EP__ _EP EP EP EP T EP EP EP EP EP EP EP E� �� - - EP- - =E�- - -E - tl'��EP P EP EP EP EP P EP EP EP CEP EP = EP 6 P EP EP EP EP EP EP -_-�- EP EP -EP��EP EP Aig _TM Ik- D1 D2 P TOP -T _ TOP P i@P TOP T T TO TOP P 2534- _ TOE OE TO - � T TO TOE TOE E OE TOE TOE T TOE - 2O 3O 4 5O O6 7O O8 90��� 10 11 7 0.07 16 5� 15 14 13j 12 253 11 10 9 �- 232 A 1 2g � � I 20 0.07 2 g1 I 8 BLOC 10 H1 1 - - 14 9R'v / 0.42 L- - - - - - - - - - -0 2529 52g 25 / 53Ln 532 3�� • �� I12 2 15 21 2 2 W. FLAT ROCK ST. 25 1 7 / 5 W. FLAT ROCK ST. � 5 ti � - - 18 B2 F2 1� 1.12 c' 11 0.37 "°- - -I I - I 1 2O 3O 4O 5O O 7O SO 9 10 11 12 13 14 15 16 17 18 19 .20 21 22 2 39 40 41 42 43 44 45 46 47 48 49 50 SR I 17 ` 0.36 116 , I 1 I I Cal Co I I ' 4 I 23 I I I 1 2 3 4 I � I I •� , _ I � II � I O = I / / • co v' i I 18 tih�� I 24 J 15 I I i t z W BL CK 5 22 1 6 BLOCK 4 / I - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 I � L I_ _ I z - - - - - - - - 19 �5 14Lu O Q 2530 S30 C1 531 E1 E2 G1 2532 Q F - ALLEY A (PRIVATE) O 13 1.51 0.14 0.14 - - - - 1.30 CL �`� 11 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -_- - - I Lu z 47 46 45 44 43 42 41 40 39 38 t Q ° L I �s`�e37 36 27 25 I I I I• Q I DC I 4 46 45 44 43 42 41 40 9 8 / 4 0 9 8 - - 7 6 5` 433 25 2 0 9 2 7 6 5 4 3- \ 12 25 • i• 19 2 82 2 2 2 Q 530 V_) 0Q_ z ,253 0 25 234 2537Lu z tea- - ---- - -- - ---- ---- - - - -- ----- ----- G -- - -- - - -- - -- - - - - z - _ - _ - --- - - _- - -- - - ---_- < I W • • • • -� • rE • • • • • �• • • - • • • �' m 1 • i • • • • • • • _ • • • • • • • - • • • • • • - -- - - f _ W. WAVERTON DR. I ) 2531_ --2532, o o \ / 2533_ 2534_ \2S3S \' - - 0 W SLi - Lu J 0 O ~ O CL 0 d a X N M U d z 0 d O0 (7 3 0 0 U D 3 w z Z V) 5 z 3 O U a O ENGINEERING L.L 0 5725 NORTH DISCOVERY WAY F BOISE,IDAHO 83713 O PHONE(208)639-6939 w kmengllp.com o I v DESIGN BY: LCK DRAWN BY: JAD a CHECKED BY: LCK Q 0 DATE: AUGUST 2025 z m oPROJECT: 24-296 C SHEET NO. C 1 OF 1 w N V G c AL £H LEGEND O��S 6, ( WELL COVER, 8" DIA. WATERTIGHT GALVANIZED STEEL BOLT DOWN COVER AND CANISTER �pENSF JJJJj�'�,, Q 2 OR 3 BOLT LID WITH 9/16" HEAD AND SAE THREADS, GASKETED FINISH GRADE O CONCRETE (COLLAR), CLASS 3000 (ISPWC SECTION 703) JJJJJJJ'' '' 860 (D� z OO 3/8" DIA HOLES OR SLOTS CUT INTO PIPE AT 3" ON CENTER - - - O TRACER WIRE SHALL BE PLACED ON OUTSIDE OF PVC PIPE, MINIMUM 18 GAUGE, INSULATED, SINGLE- JJJJ��'�, r s� 815125 0 CONDUCTOR COPPER WIRE, INSULATION COLOR SHALL BE GREEN WITH THREE 6" DIAMETER COILS -III ° s ITI=ITI-11 :P s PIPE SHALL BE PERFORATED PVC, ASTM D-3035, SDR 35. WELLS BACKFILLED IN A PIT REQUIRE 6" JJJJJ/ �C' 9TF OF PIPE. DRILLED WELLS MAY USE 4" PIPE JJi �/ N )LA, N FABRIC OVER CHIP /DRAIN ROCK _ -- JNC ONWOVEN FILTER FABRIC AROUND OPENINGS AND BOTTOM S _� ---------------- --- - ----- A _- 0 POLYPROPYLENE FIBER REINFORCEMENT AT 1 1/2 LBS/CY aeP o�P� III-Ili, III-11 3 Ap 9 6" STANDARD CURB O BACKFILL MATERIAL TO MATCH STORAGE MEDIA FOR OBSERVATION WELLS LOCATED WITHIN A BMP FACILITY. I �� �� ASPHALT USE PIPE BEDDING CHIPS FOR OBSERVATION WELLS LOCATED OUTSIDE BMP FACILITIES I ��° ��° - 1 --� _ ------------- PERSPECTIVE VIEW ^r Sr .•I 3 NOTES: I N.T.S. 5 PLAN CONCRETE COLLAR 1. GROUNDWATER OBSERVATION WELLS ARE FOR MEASUREMENT OF GROUNDWATER LEVELS WITHIN OR NEAR z STORM DRAINAGE FACILITIES ~ N.T.S. 2. THIS DETAIL IS FOR WELLS INSTALLED BY DRILLING OR BY EXCAVATED PITS - - - - - - - - - - -J LIP OF GUTTER 3. LOCATION OF GROUNDWATER OBSERVATION WELLS SHALL BE APPROVED BY ACHD H LL 4. OBSERVATION WELLS NOT ALLOWED IN CURB OR VALLEY GUTTER SECTION PLAN VIEW 6 w 0 6 N.T.S. o Q III=III=III=III=III - = - 18"0 =-=-=-=1 3 _ 1=1 1=1 11=1 11=1 1= III=III=III=III=i m 11-III=III=III-I : _ -III-III-III=III- -III-III-III III=1 1=1 11=1"- _� BACK OF CURB A b ° o�= 11-III=1I = -III=III_ SIDEWALK =III= 5 II-In-' 8" C900 PIPE 0 �II II> z W 8 ,_ r- 3 A x PLAN 4 W L� UTLET 6 SECTION CONCRETE COLLAR FLo o BAFFLE WALL N.T.S. z > N.T.S. ELEV B FLOW O ELEV A N w 4 4 ELEV D w w INLET BAFFLE WALL � 4 #4 EPDXY BAR ELEV C 20' STD SIDEWALK 2% MAX ASPHALT o 9 SECTION A-A 8" c9oo PIPE N.T.S. NOTES 6" DEEP ° 1. SAND AND GREASE TRAP USED FOR SUBSURFACE FACILITIES ONLY ^ �' 3"-6" ANGULAR RIPRAP IN SWALE LEGEND: 0.5' TYP a� p 7 � z (D MANHOLE FRAME AND COVER PER SD-617 (TYPICAL) SECTION A-A z LOCATION AND FL ELEV. PER DESIGN PLANS (TYPICAL) SECTION H 1-FT USE GRADE RINGS (TYPICAL) N.T.S. a N.T.S. 1-FT < H <= 2-FT USE 24" DIA RCP RISER LEGEND: 2-FT < H <= 10-FT USE MANHOLE CONE & 48" DIA RISERS Oi STANDARD TYPE 1 INLET PER SD-601 OF ISPWC/ACHD SUPPLEMENTAL WITH THESE MODIFICATIONS. O EL. A > EL. B BY 0.10' MIN FRAME & GRATE PER ISPWC/ACHD SUPPLEMENTAL SD-609/610A EL. D < EL. B BY 0.10' MIN EL. C < EL. B BY 0.50' MIN. UNLESS OTHERWISE APPROVED BY ACHD NOTES: 8 WATERTIGHT SEAL 1. REQUIRED WITH INFILTRATION SWALE DESIGN FOR ATTACHED SIDEWALK s PRECAST BOX MANUFACTURER SHALL MARK FLOW DIRECTION AND LABEL INLET OR OUTLET 2. SEE SWALE BMPS FOR SWALE DETAILS ON SIDE OF BOX 2017 ACHD REVISION 2017 ACHD REVISION IDAHO WORKS GROUNDWATER STANDARDS GROUNDWATER 2015 SAND AND GREASE TRAP STANDARD DRAWING SHALLOW INLET STANDARD DRAWING STANDARD DRAWING ACHD S ORDELANES DESIGN BMP O1 ACHD STORMWATER DESIGN STANDARD DRAWING CONSTRUCTION OBSERVATION WELL SD- 627 CONSTRUCTION OBSERVATION WELL SD- 627 1 OF 2 GUIDELINES ATTACHED WALK DETAIL 10 (ACHD SUPPLEMENT) 1 OF 2 (ACHD SUPPLEMENT) 2 OF 2 GROUND NO TREES ARE ALLOWED WITHIN WATER 10' OF THE OUTSIDE PERIMETER NO TREES AREz ALLOWED NEAR Q OBSERVATION OF THE SEEPAGE BED LENGTH VARIES, � PERIMETER N THE O J GROUND WATER WELL #2 NO TREES ARE ALLOWED WITHIN SEE TABLE THIS z OBSERVATION WELL 1A-.-, ELEV. - "A" (MIN.) SHEET # SEEPAGE BED FINISHED GROUND 10' OF THE OUTSIDE PERIMETER iv 5V����� �����' OF THE SEEPAGE BED 7 z /�� ✓j��j ELEV. - "A" (MIN.) A,B 50' ��j���j� � � /��� � � ELEV. - "A" (MIN.) MIN. A����. ��A�A�� 'V�A�A���A� AAAA �� �A�A�A�A�A z ��i��i� 5 �i��i� s �i i��i��i��i�ii� i��i��i��i��i� Os .�i��i��i��i��i��� O�O� 6\5 C - W ELEV. - "B" ���� ���� �� �������� ELEV. - "B" ���������� ������������ o 0 0 o ELEV. - "B" V) SAND AND GREASE TRAP � �"" c j u 3 3 u 0 0 \\ ui ww / Lu m w ELEV. - .,C., ELEV. - ,C, C? Q 6 O m w - - \ EL : Oa EE o c o o tea= w QSDI ��� Z_ w J 5 Z_ 5 w J ~N 5 3 O 5w� 5 5 Qm Qm �Lj- m m z- - J 18"0 PERFORATED �cwn� �� �� OO�OO�O O ��� ~ Q 5 LF OF 18"0 ADS N-12 HIP W w o 0 2 0 3: w - Q ADS N-12 HP SOLID WALL PIPE a_ CLw w O O 2 O N Q 5 W TRANSITION 5' IN BED NON-PERFORATED L� A,B OO�OOO�OOO�OO 8 w - TO PERFORATED PIPE LENGTH VARIES, SEE TABLE THIS SHEET ELEV. - "D" 2 ELEV. - "D" 2 ELEV. - "C" z w Lu PLAN VIEW Z _ Lu 1. ISPWC 801 OR ASTM C33 FILTER SAND. w O WIDTH VARIES SEE WIDTH VARIES SEE 2. 3/4" - 2" ANGULAR ROCK. O O 04 0 z Q MAX. HSGW M ' MAX. HSGW M 3. 12"0 PERFORATED ADS PIPE. p p p SAND AND GREASE TRAP PER TABLE THIS SHEET TABLE THIS SHEET OR ROCK OR ROCK 4. SUITABILITY OF SUBGRADE TO BE VERIFIED BY GEOTECHNICAL = ACHD REQUIREMENTS. REFER TO E WATERTIGHT CONNECTION 18"0 PERFORATED ADS ELEVATION ELEVATION ENGINEER. ELEV. - "D" ACHD DETAIL BMP 01. FINISH GROUND 5. NON-WOVEN FABRIC SHALL BE PROPEX GEOTEX 401 OR APPROVED z_ 1Q ADDITIONAL INFORMATION PER PLAN. EQUAL MEETING ACHD STORMWATER DESIGN GUIDELINES SECTION N-12 HP 18" ADS CAP 4 4 8202.23. OVERLAP MINIMUM OF 1-FT TOP AND SIDES ONLY. WIDTH VARIES, SEE J Q KEY 6. MINIMUM OF 1.-FT COVER FROM TOP OF BED TO FINISH GROUND IN MAX. HSGW TABLE THIS SHEET J = O 1. ISPWC 801 OR ASTM C33 FILTER SAND. LANDSCAPE AREAS. INSTALL WOVEN GEOTEXTILE FABRIC OVER TOP OF OR ROCK O BED. WOVEN FABRIC SHALL BE PROPEX GEOTEX 401F OR APPROVED ELEVATION 0% SLOPE 2. 3/4" - 2" ANGULAR ROCK. EQUAL MEETING ACHD STORMWATER DESIGN GUIDELINES SECTION 3. 18"0 PERFORATED PIPE. INSTALL PERFORATIONS PER ACHD STORMWATER DESIGN I Y 8202.23. GUIDELINES DETAIL BMP 20 AND DETAIL ON THIS SHEET. 1. ISPWC 801 OR ASTM C33 FILTER SAND. 7. ADS NYLOPLAST 12" DRAIN BASIN. 4 4. SUITABILITY OF SUBGRADE TO BE VERIFIED BY GEOTECHNICAL ENGINEER. 2. 2" WASHED DRAIN ROCK OR 3/4" - 2" ANGULAR ROCK. 8. 6"0 ADS PIPE. CONNECT TO 12"0 PERFORATED ADS PIPE. MINIMUM OF 20' 5. NON-WOVEN FABRIC SHALL BE PROPEX GEOTEX 401 OR APPROVED EQUAL 3. 18"0 PERFORATED PIPE. INSTALL PERFORATIONS PER ACHD STORMWATER BAFFLE SPACING y ,,y y MEETING ACHD STORMWATER DESIGN GUIDELINES SECTION 8202.23. OVERLAP DESIGN GUIDELINES DETAIL BMP 20 AND DETAIL ON THIS SHEET. GENERAL NOTES: 4" OF CHIPS PIPE BEDDINGV 6. MINIMUM OF 1-FT TOP AND SIDES ONLY. 4. SUITABILITY OF SUBGRADE TO BE VERIFIED BY GEOTECHNICAL ENGINEER. 6. FOR SEEPAGE BEDS IN THE PUBLIC RIGHT-OF-WAY A MINIMUM OF 1.0-FT 5. NON-WOVEN FABRIC SHALL BE PROPEX GEOTEX 401 OR APPROVED 1. CONTRACTOR SHALL NOTIFY ENGINEER IMMEDIATELY N GROUNDWATER OR COVER FROM TOP OF BED TO PAVEMENT SUBGRADE. INSTALL WOVEN GEOTEXTILE EVIDENCE OF GROUNDWATER IS ENCOUNTERED WITHIN 3-FEET TO THE TOP SECTION VIEW C-C: SEEPAGE BEDS 18'0 SOLID WALL ADS N-12 HP EQUAL MEETING ACHD STORMWATER DESIGN GUIDELINES SECTION 8202.23. OF SAND. (EXTEND 5' INTO SEEPAGE BED) FABRIC OVER TOP OF BED. WOVEN FABRIC SHALL BE PROPEX GEOTEX 401 F OR OVERLAP MINIMUM OF 1-FT TOP AND SIDES ONLY. APPROVED EQUAL MEETING ACHD STORMWATER DESIGN GUIDELINES SECTION 2. REFER TO "GEOTECHNICAL DATED INVESTIGATION APEX WEST SUBDIVISION" OUTSIDE OF PUBLIC R 0 W (COMMON LOTS z 6. FOR SEEPAGE BEDS OUTSIDE OF PUBLIC RIGHT-OF-WAY A MINIMUM OF PREPARED BY ATLAS, DATED FEBRUARY 8, 2022, FOR FURTHER GROUND WATER OBSERVATION WELL PER 8202.23• 1.5-FT COVER FROM TOP OF BED TO FINISH GRADE WITHIN LANDSCAPE DETAIL. EXTEND MINIMUM OF 1' BELOW AREAS. INFORMATION. DESIGN INFILTRATION RATE = 8"/HR. O N THE BOTTOM OF SAND LAYER 3: SECTION VIEW SECTION VIEW A-A: SEEPAGE U SECTION VIEW B-B: SEEPAGE BEDS PLAN AND PROFILE BEDS WITHIN PUBLIC ROW OUTSIDE OF PUBLIC ROW (COMMON LOT) Z 0 Z 0 z GENERAL NOTES O A. GROUNDWATER ELEVATIONS ARE EXPECTED TO REMAIN AT OR BELOW 13 FEET FROM EXISTING GROUND SURFACE. 1 SEEPAGE BED TABLE THE DESIGN INFILTRATION RATE IS 8 IN/HR BASED ON THE TEST PIT LOGS, WHICH SHOW POORLY GRADED U D5 gs. z GRAVEL AT THE APPROXIMATE BOTTOM DEPTH OF THE PROPOSED SEEPAGE BEDS. FOR ADDITIONAL INFORMATION DESIGN INFILTRATION REFER TO THE GEOTECHNICAL ENGINEERING REPORT "POLLARD LANE REALIGNMENT - POLLARD LANE & CHINDEN >/� \/ SEEPAGE BED SECTION BED LENGTH (FT) BE�FT�WIDTH BED DEPTH (FT) ELEVATION "A" ELEVATION "B" ELEVATION "C" ELEVATION "D" GROUND WATER EL. DESIGN VOLUME (CF) RATE (IN/HR) BOULEVARD" PREPARED BY MTI, DATED AUGUST 31, 2016 AND GROUNDWATER DATA PREPARED BY NATURAL O RESOURCE SOLUTIONS, LLC. ENGINEERING LL SIB #1 (PUBLIC) B-B 65 17.5 7.5 2529.05 2526.70 2524.27 2519.20 2515f 4,210 8.0 B. ALL DRAINAGE STRUCTURES SHALL BE HS25 OR GREATER LOAD RATED. c�3, 3 C. ALL GEOTEXTILE SEAMS SHALL OVERLAP 1 FOOT MINIMUM. 0 5725 NORTH DISCOVERY WAY D. BED WIDTH SHALL REMAIN CONSTANT. O SIB #2 (PRIVATE) B-B 51 15 7.5 2529.69 2527.67 2524.57 2520.17 2516f 2,830 8.0 E. IF ROCK IS ENCOUNTERED, CONTRACTOR MUST HAVE A PERCOLATION TEST PERFORMED BY A SOILS ENGINEER BOISE,IDAHO 83713 AFTER SEEPAGE BED IS FULLY EXCAVATED. (NOTE: AN ACHD INSPECTOR MUST BE PRESENT FOR THE TEST). IF PHONE(208)639-6939 SIB #3 (PUBLIC) A-A 34 15 7.5 2530.75 2528.00 2525.96 2520.50 2516t 1,893 8.0 THE PERCOLATION IS LESS THAN SPECIFIED BY THE SOILS REPORT AND ENGINEER, CONTRACTOR MAY NEED TO kmengllp.com z N SIB 4 PUBLIC A-A 111 10 7.5 2530.92 2528.86 2526.18 2521.36 2518t 4,090 8 O BLAST OR BORE TO CREATE CONDUIT FOR DRAINAGE TO OCCUR OR RE-DESIGN THE SYSTEM TO ACHIEVE THE N # (PUBLIC) REQUIRED INFILTRATION. DESIGN BY: LCK F. STORAGE VOLUME DOESN'T INCLUDE SAND WINDOW. SIB #5 (PRIVATE) B-B 55 12 7.5 2531.68 2528.99 2526.94 2521.49 2518t 2,447 8.0 G. WATER SERVICES, SEWER SERVICES, AND PRESSURE IRRIGATION MAINS CROSSING SEEPAGE BEDS SHALL BE DRAWN BY: JAD INSTALLED PER ACHD REQUIREMENTS. o SIB #6 (PUBLIC) B-B 32 15 7.5 2534.38 2531.53 2529.53 2524.03 2521t 1,885 8.0 H. FOR UNDERGROUND INFILTRATION SYSTEMS, INSTALL ELECTRONIC MARKERS ON EACH CORNER OF THE FACILITY. CHECKED BY: LCK G THE CONTRACTOR SHALL COORDINATE WITH THE ACHD INSPECTION DEPARTMENT FOR PLACEMENT OF THE 18" PERF PIPE SIB #7 (PRIVATE) C-C 12 12 7.5 2533.87 2532.87 - 2525.37 2521 t 508 8.0 MARKERS DURING CONSTRUCTION AND PRIOR TO BACKFILLING. WQ DATE: AUGUST 2025 z o - I. CONTRACTOR SHALL VERIFY INFILTRATION RATE AFTER THE FACILITY IS FULLY EXCAVATED WITH THE ACHD PROJECT: 24-296 SIB #8 (PRIVATE) C-C 9 9 7.5 2534.60 2533.60 2526.10 2521t 292 8.0 INSPECTOR PRESENT. PERFORATION SCHEDULE S J. CONTRACTOR SHALL NOTIFY THE ENGINEER IMMEDIATELY IF GROUNDWATER IS ENCOUNTERED WITHIN 3-FEET OF 3/8" PERFORATIONS IN VALLEY SHEET NO. _ THE BOTTOM DESIGN ELEVATION FOR ANY INFILTRATION FACILITY AND/OR IF IT IS HIGHER THAN ANTICIPATED. OF CORRUGATED PIPE. 5 EA ON 18". J SEEPAGE BED DETAIL #1 C4. 1 w N N NTS Ii a SHEET NOTES KEYNOTES A. SEE SHEET C1.1 FOR GENERAL AND SANITARY SEWER SS�ONAL £Nc/ NOTES. O UTILITY MAIN/MAIN CROSSING o�� ���ENSF 'y MAINTAIN VERTICAL AND HORIZONTAL B. STATIONING BASED ON SEWER ALIGNMENT CENTERLINE. POTABLE/NON-POTABLE MAIN LINE SEPARATION PER CITY OF MERIDIAN REQUIREMENTS. SEE WATER 860 C. SEWER MANHOLES SHALL MEET ISPWC SD-501 AND CITY NOTE 2 SHEET C1.1 FOR ADDITIONAL 8/5/25 OF MERIDIAN SUPPLEMENTAL SPECIFICATION TO THE INFORMATION. r JJ �o Q ISPWC. INSTALL MANHOLE COVER AND FRAME PER ISPWC OF SD-507. © UTILITY MAIN/SERVICE CROSSING y�//\� C Y' D. INSTALL STANDARD SERVICE MARKERS PER CITY OF MAINTAIN VERTICAL AND HORIZONTAL MERIDIAN STANDARD DRAWING SW3. POTABLE/NON-POTABLE MAIN/SERVICE OR SERVICE/SERVICE LINE SEPARATION PER CITY OF E. CONTRACTOR IS RESPONSIBLE FOR INSTALLING SEWER MERIDIAN REQUIREMENTS. SEE WATER NOTE 3 SERVICES 5' BEYOND JOINT TRENCH EASEMENT. VERIFY SHEET C1.1 FOR ADDITIONAL INFORMATION. EXACT LOCATION OF SEWER SERVICES WITH OWNER PRIOR TO INSTALLATION. SERVICE LENGTH AND INVERT ARE 1. REMOVE WATER-TIGHT PLUG AND CONNECT TO BASED ON STUB LOCATION. STATIONING TAKEN FROM EXISTING 8" BLOCK-OUT PER CITY OF MERIDIAN CENTERLINE OF SEWER ALIGNMENT. REQUIREMENTS. F. INSTALL 4" DIAMETER SEWER SERVICES PER ISPWC 2. INSTALL 8" BLOCK-OUT AND WATER-TIGHT SD-511 (TYPE A-F) WITH MINIMUM SLOPE OF 2% FROM PLUG FOR FUTURE CONNECTION. w THE PROPERTY LINE TO SANITARY SEWER MAIN. a 0 G. NO PERMANENT STRUCTURES (INCLUDING BUILDINGS, CARPORTS, TRASH ENCLOSURES), TREES, OR DEEP EXISTING SEWER SEWER ALIGNMENT "C" SEWER ALIGNMENT "B„ ROOTING BUSHES TO BE WITHIN PUBLIC WATER AND THIS SHEET SEWER, OR RECYCYLED WATER MAIN EASEMENT. MAIN SEE SHEET C5.1 Cm 1 co I I 29 I 19 i co 10 m m l a I m I I 28 Z : 1 20 1 O a? m 1 1 N N m 1 I �FA - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - c/) O° I co I 1 EP EP EP EP EP EP EP EP EP EP EP EP EP EP E F 1 FP -EP EP EP 2 z BLOCK 6 SSMH #5 (48-INCH) w F_ N I 1 27 I �O I 21 I m 0 I EP EP EP P EP EP EP EP EP EP EP E EP STA: 3+50.44 OFFSET: 0.00' EP EP EP oC _ TOP 'OP-N: 729558.02, E: 2435247.33. To T 1 44Cf) I BLOCK 5 rn SEWER ALIGNMENT N I m m SSMH #18 (48-INCH) O m I 6 PI 6 1 6 PI 6 6 PI 6 R I 6 PI 6 PI 6 PI 6 PI G 6 PI 6 PI 6 PI 6 PI 6 PI 12 =w 6 PI- ® BLOCK 6 ® > "A", THIS SHEET 1 I I 26 I a O 1 STA: 4+46.93 OFFSET: 0.00' Q N: 729654.51, E: 2435248.26 p SEWER MAIN TO BE °D `° I - I I O O O O O O O O 10 11 i w �� CONSTRUCTED WITH N _ 12 I STA: 2+06.95 STA: 2+66.95 STA: 3+26.92 STA: 3+86.92 STA: 4+46.92 STA: 5+06.95 STA: 5+66.95 STA: 6+26.95 a _ 1 E 23 E _ _E `' 1 STA: 1+00.00 STA: 1+46.92 INV: 2525.06 1 = v POLLARD NORTH _ �o sO 90 m I m I N INV: 2525.70 INV: 2524.79 INV: 2524.55 INV: 2524.31 INV: 2524.07 INV: 2524.32 INV: 2524.69 INV: 2525.44 INV: 2525.81 I p0 L: 37.5' L: 37.5' L: 37.5' O rn 1 SUBDIVISION No. 1 1 I I L: 39.5' L: 37.5' r � 1 00 � 1 +00 �1 I 1 L: 37.5' L: 37.5' L: 37.5' L: 37.5' L: 37.5' I � � �W a„SI I N. WOODHEADAVE. 1 p I - - - - - - - - - - - - - - - - - - - - - - - - - - ® - - o L8I 1 .. o 1 Q I N �o ® 180• °° z -. 1 _ Js..w 8..w1j, �o u; 11 J 1 W a w1 00 a w a w 2+ w a w 3+00 a„w a"w 4+00 a„w a„w : 5 a"w s"w 6+Oa w $w O0 / 00 eSSMH #5 (48-INCH) 1 1 a 1 I7 IB"S 8"S "S 8'S 8'S 8" I 8"S 8"$ 18" L - - - _ �' SSMH #4 (48-INCH)i e z W. FLAT ROCK ST. SSMH #20 (48-INCH) 0 STA: 3+50.44 OFFSET: .00' SSMH #19 (48-INCH) �0 F F STA: 3+05.36 OFFSET: 0.00' 39 STA: 4+98.93 OFFSET: 0.00' 1 N: 729558.02, E: 2435247.33 STA: 1+00.00 OFFSET: 0.00 o• a� i d„s F F N: 729512.94, E: 2435246.90 E E F 1 1 - - -N: 729559.91, E: 2435049.84, N: 729563.73, E: 2434650.94 4"� -4r _4 4"Pr a"Fr "Fr 'Pr "Pr- - T T - - 1 BLOCK 41 s 16 o I I Ia I I 1 vi O I SEWER MAIN TO BE _0 m l m 1 40 CONSTRUCTED WITH , _u I O BLOCK 5 W 1 1 I 1 °° 1 POLLARD NORTH 1 1 3 12W W 13 14 15 16 17 18 19 20 21 22 U) SUBDIVISION No. 10 1 1 1 1 O2 O3 4O O O O O8 O 10 11 W OD Cn N ALIGNMENT "A" PLAN AND PROFILE ALIGNMENT " 6" PLAN AND PROFILE o 0 50 100 150 0 5 10 15 0 50 100 150 0 5 10 15 z z W w J J Plan/Profile Scale: 1" =50' Profile Vertical Scale: 1" = 5' Plan/Profile Scale: 1" = 50' Profile Vertical Scale: 1" = 5' z Q O � 00 - oc 2540 2540 2540 2540 > w z z p as .-�v O W Z N V) M 1 5 O Z 2 0 �. .. .: ^ 0 ^^^ W z ` Z Z 0 �: O 00 ^� W W �i Z 2 U O Z O ^� 20 . .. .. .� Q W Q Q Z o 00 ao z a0 ao ao (0 U . v: =0 w U o . . . Co \ J J W 00 1 O (0 CO C0 Z O U O 00 O ^ Z_W 00 00 00 I, ^ 10 00 00 00 0 N N N 00 O Z 2 0 I O c0 c0 c0 v l 2535 � � � � 000 Ooo `N' z0 - 00 00 NNN o � -moo � N �,� r �_ 2535 2535 N �'0 _4 4 4 �, 2535 2 w Q cm �O� N +Lo ? 00C�C�O � L0 ON � 04 000 N L0C;6 () N W - - +� .. 2r�NZZZ 0 �0� � N Cn C14O� � N �r� O 00 �MNNN H ��NZ 0 ��� » > > +� Z �ONN D 0C. N =MNZZZ 0O O Z Z cn�� > > v)v)QE zz z =ItC.I - 0 =�Nz O N00o; �n �Q W W (n(n0 Z Z �Q ON N H N�� > > > > - � > > a > > FINISHED GROUND + D z z z z z C U)U) z z U)U) Z I m�N Z 0 G 2530 2530 2530 EXISTING GROUND Cn f z Z 2530 0 W 0 (D ��� - - - - - - - - L_u Q Q O Q J Ln p � 2525 2525 2525 Q 2525 I N Q I N FL EXISTING GROUND N FINISHED GROUND N 398.9' of 8" PVC @ 2520 2520 2520 0.60% 2520 z X 1J�G+ O N of 8„ 0vC 2515 96.5' of 8" vc 0.41% 2515 2515 2515 z DC Z 45.1' of 8" PVC @ 0.40% N 7 L EXISTING GROUND CENTERLINE OF SEWER PIP ALIGNMENT EXISTING GROUND CENTERLINE OF SEWER PIPE ALIGNMENT O 2510 FINISH GROUND CENTERLINE OF SEWER PIP ALIGNMENT 2510 2510 FINISH GROUND CENTERLINE OF SEWER PIPE ALIGNMENT 2510 U z N z r 00 L N O N L N � N O N r O N O r 0 00 r Cn Cn O r� LO O O _ O 00 � � M fn I� O fn N L0 00 to 00 L0 _ O 0) 0) 0) 06 00 00 00 00 Cn O O Cn O O O PO O O Cfi Oi fn 00 00 00 00 Cn 0; of O O O O J i ) N N N N N N N N N N N N N V) V) M O N L N LO (V L N LO N N N N N N M n n n LL 3 N N N N CA N CA N � N N N N 0 N N N 0 N CV N N E N G I N E E R I N G N N N N N N N N N N N N N N N N N 0 5725 NORTH DISCOVERY WAY 3 BOISE,IDAHO 83713 O PHONE(208)639-6939 3+00 3+50 4+00 4+50 5+00 1+00 1+50 2+00 2+50 3+00 3+50 4+00 4+50 5+00 5+50 6+00 6+50 7+00 7+50 kmengllp.com DESIGN BY: LCK DRAWN BY: JAD z o CHECKED BY: LCK Q v DATE: AUGUST 2025 z o PROJECT: 24-296 5 a SHEET NO. J W C5.0 N V i 2 APPENDIX B - TABLES Table 1 - Peak Flow Rates and Runoff Volumes Post-Development Peak Flow Rates (cfs) Tc (min.) 25-yr 100-yr Basin Al 10.0 0.07 0.10 Basin B1 14.4 1.04 1.45 Basin B2 17.8 1.03 1.43 Basins B1- B2 17.8 1.90 2.66 Basin C1 17.2 1.28 1.78 Basin D1 10.0 0.08 0.12 Basin D2 10.0 0.08 0.12 Basin D1- D2 10.0 0.17 0.23 Basin E1 10.0 0.20 0.28 Basin E2 10.0 0.20 0.28 Basin E1- E2 10.0 0.41 0.57 Basin E1, E2, D1, D2 10.0 0.81 1.13 Basin F1 17.4 0.76 1.07 Basin F2 17.4 0.71 1.00 Basins F1- F2 17.4 1.48 2.06 Basin G1 10.0 1.31 1.83 Basin H1 14.5 0.51 0.71 Basin H2 18.0 0.42 0.59 Basins H1- H2 18.0 1 0.85 1.19 Basin 11 10.0 0.27 0.38 Basin 12 10.0 0.16 0.22 Post-Development Runoff Volumes Volume (cf) Required Basins Al, Pond#1 131 Basins B1- B2, SB#1 4,210 Basins C1, SB#2 2,830 Basins D1 - D2, E1 - E2,SB#3 1,514 Basins F1- F2, SB#4 3,272 Basins G1, SB#5 2,447 BasiNS H1 - H2, SB#6 1,885 Basin 11, SB#7 508 Basin 12, SB#8 292 APPENDIX C - CALCULATIONS POST-DEVELOPMENT 25-YEAR CALCULATIONS ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Al 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 4 Enter number of storage facilities(25 max) 20 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 1,600 0 1,305 Acres 0.07 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.57 7 User Calculate Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 min 10 Min. Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients"f Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet VelocityV Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Segment 2:Gutter Shallow Concentrated Flow Heavy areas 0. 90 Parks,Cemeteries 0.1030-0.25 b 0.001 0.619 57 0.7 1.4 playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 21 0.240 3.1 6.7 Computed Tc= 8.0 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qpezk 0.07 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 82 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 9 ft' Concrete 0.95 Primary Treatment/StorageBasin V 85 W Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 94 fti Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0.. Steep:>6% 0.13 0.18 0.23 0.. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/23/2025,9:41 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Bl 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 14,260 21,707 0 Acres 0.83 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.68 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.004 0.619 313 1.3 4.1 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 36 0.240 3.5 10.3 Computed Tc= 14.4 User-Entered Tc= 14.4 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 1.04 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,391 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,210 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 139 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,252 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,391 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/23/2025,9:41 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN B2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 17,079 23,137 8,699 Acres 1.12 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.59 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.004 0.619 456 1.3 5.9 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 43 0.240 3.6 11.9 Computed Tc= 17.8 User-Entered Tc= 17.8 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.56 in/hr 9 Calculate the Post-Development peak discharge(ClPeak) Clpezk 1.03 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,635 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,421 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 163 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,471 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,635 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/23/2025,9:49 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Bl AND B2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 31,339 44,844 8,699 Acres 1.95 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.63 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 17.8 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.56 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 1.90 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 3,026 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 2,631 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 303 ft' Concrete 0.95 Primary Treatment/StorageBasin V 2,723 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 3,026 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/23/2025,9:43 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Cl 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 13,208 44,613 8,132 Acres 1.51 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.54 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.007 0.619 323 1.7 3.2 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 53 0.240 3.8 14.0 Computed Tc= 17.2 User-Entered Tc= 17.2 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.56 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 1.28 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 2,034 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,769 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 203 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,831 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 2,034 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/23/2025,9:44 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Dl 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 1,951 0 1,064 Acres 0.07 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.65 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.004 0.619 51 1.3 0.7 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 24 0.240 3.2 7.4 Computed Tc= 8.1 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.08 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 112 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) V« 97 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 11 ft' Concrete 0.95 Primary Treatment/StorageBasin V 101 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 112 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/23/2025,9:44 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN D2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 1,951 0 1,080 Acres 0.07 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.65 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.08 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 112 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 97 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 11 ft' Concrete 0.95 Primary Treatment/StorageBasin V 101 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 112 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025.xism 8/5/2025,4:16 PM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Dl AND D2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 3,902 0 2,144 Acres 0.14 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.65 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.17 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 224 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 194 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 22 ft' Concrete 0.95 Primary Treatment/StorageBasin V 201 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 224 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025.xism 8/5/2025,4:18 PM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN El 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 4,879 0 1,287 Acres 0.14 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.77 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.007 0.619 181 1.6 1.8 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 17 0.240 3.0 5.6 Computed Tc= 7.5 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.20 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 272 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 236 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 27 ft' Concrete 0.95 Primary Treatment/StorageBasin V 245 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 272 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,8:55 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN E2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 4,903 0 1,287 Acres 0.14 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.77 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.007 0.619 186 1.6 1.9 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 18 0.240 3.0 5.9 Computed Tc= 7.8 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.20 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 273 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 237 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 27 ft' Concrete 0.95 Primary Treatment/StorageBasin V 246 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 273 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,8:56 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN El AND E2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 9,782 0 2,574 Acres 0.28 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.77 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.41 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 545 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 474 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 54 ft' Concrete 0.95 Primary Treatment/StorageBasin V 490 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 545 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,8:54 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �WPs for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASINS Dl,D2,El,AND E2-SEEPAGE BED 3 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 13,684 9,782 11,926 Acres 0.81 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.54 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning In Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.81 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,088 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 946 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 109 ft' Concrete 0.95 Primary Treatment/StorageBasin V 979 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,088 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,8:57 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Fl 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 12,132 19,548 41 Acres 0.73 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.67 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.007 0.619 534 1.7 5.3 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 44 0.240 3.6 12.1 Computed Tc= 17.4 User-Entered Tc= 17.4 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.56 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.76 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,215 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,056 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 121 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,093 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,215 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,8:58 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN F2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 10,966 17,370 8,376 Acres 0.84 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.54 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 17.4 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.56 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.71 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,137 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 989 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 114 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,023 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,137 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,8:58 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Fl AND F2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 23,098 36,918 8,417 Acres 1.57 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.60 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 17.4 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.56 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 1.48 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 2,352 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 2,045 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 235 ft' Concrete 0.95 Primary Treatment/StorageBasin V 2,117 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 2,352 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,8:59 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-Gl 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 13,215 34,863 8,620 Acres 1.30 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.54 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.004 0.619 467 1.3 6.1 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 50 0.0 Computed Tc= 6.1 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 1.31 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,759 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,530 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 176 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,583 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,759 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,8:59 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-H1 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 6,627 11,485 Acres 0.42 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.66 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.010 0.619 268 2.0 2.2 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 45 0.240 3.7 12.3 Computed Tc= 14.5 User-Entered Tc= 14.5 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.51 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 686 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 597 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 69 ft' Concrete 0.95 Primary Treatment/StorageBasin V 618 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 686 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:00 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-H2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 7,162 8,739 5,473 Acres 0.49 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.55 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.010 0.619 286 2.0 2.3 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 61 0.240 3.9 15.7 Computed Tc= 18.0 User-Entered Tc= 18.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.56 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.42 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 668 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 581 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 67 ft' Concrete 0.95 Primary Treatment/StorageBasin V 602 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 668 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:00 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-H1 AND H2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 13,788 20,224 5,473 Acres 0.91 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.60 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 18.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.56 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.85 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,355 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,178 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 135 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,219 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,355 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:01 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Steps for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name Drainage Basin 11 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 4 Enter number of storage facilities(25 max) 2 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 2,399 6,145 5,868 1,343 Acres 0.36 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 0.35 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.41 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate to Min. Estimated Runoff Coefficients for Various Surface min - Type of Surface Runoff Coefficients"( 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 in/hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.27 cfs Urban neighborhoods 0.50-0.70 Residential Single Family 0.35-0.50 10 Calculate total runoff vol(V)(for sizing primary storage) V 365 ft3 Multi-family 0.60-0.75 V=CI(Tc=60)Ax3600 Residential(rural) 0.25-0.40 11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70 Industrial and Commercial Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Light areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) err 318 W Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,cemeteries 0. Playgrounds 0.20-0.0-0.35 5 Railroad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 37 ft' Concrete 0.95 Primary Treatment/StorageBasin V 329 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 365 ftj Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_I1-12 7/3/2025,3:04 PM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �WPs for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name Drainage Basin 12 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 25 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 664 4,653 7,182 Acres 0.29 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.29 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 Min. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients N 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 1.85 n/hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.16 cfs Urban neighborhoods 0.50-0.70 Residential Single Family 0.35-0.50 10 Calculate total runoff vol(V)(far sizing primary storage) V 210 fta Multi-family 0.60-0.75 V=CI(Tc=60)Ax3600 Residential(rural) 0.25-0.40 11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70 Industrial and Commercial Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Light areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vr, 182 ft' Heavy areas o.90 Parks,Cemeteries 0.10-0.25 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 21 ft' Concrete 0.95 Primary Treatment/StorageBasin V 189 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 210 ft' Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 O. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 0. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_I1-12 7/3/2025,3:04 PM Version 10.5,November 2018 POST-DEVELOPMENT 100-YEAR CALCULATIONS ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Al 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) 20 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 1,600 0 1,305 Acres 0.07 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.57 7 User Calculate Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 min 10 Min. Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients"f Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet VelocityV Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Segment 2:Gutter Shallow Concentrated Flow Heavy areas 0. 90 Parks,Cemeteries 0.1030-0.25 b 0.001 0.619 57 0.7 1.4 playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 21 0.240 3.1 6.7 Computed Tc= 8.0 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qpeak 0.10 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 131 fti V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr, 82 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 13 ft' Concrete 0.95 Primary Treatment/StorageBasin V 118 W Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 131 fti Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0.. Steep:>6% 0.13 0.18 0.23 0.. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:06 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Bl 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 14,260 21,707 0 Acres 0.83 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.68 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.004 0.619 313 1.3 4.1 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 36 0.240 3.5 10.3 Computed Tc= 14.4 User-Entered Tc= 14.4 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 1.45 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,936 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,210 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 194 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,742 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,936 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:06 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN B2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 17,079 23,137 8,699 Acres 1.12 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.59 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.004 0.619 456 1.3 5.9 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 43 0.240 3.6 11.9 Computed Tc= 17.8 User-Entered Tc= 17.8 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.18 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 1.43 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 2,274 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,421 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 227 ft' Concrete 0.95 Primary Treatment/StorageBasin V 2,047 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 2,274 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:06 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Bl AND B2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 31,339 44,844 8,699 Acres 1.95 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.63 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 17.8 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.18 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 2.66 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 4,210 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 2,631 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 421 ft' Concrete 0.95 Primary Treatment/StorageBasin V 3,789 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 4,230 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:06 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Cl 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 13,208 44,613 8,132 Acres 1.51 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.54 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.007 0.619 323 1.7 3.2 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 53 0.240 3.8 14.0 Computed Tc= 17.2 User-Entered Tc= 17.2 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.18 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 1.78 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 2,830 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,769 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 283 ft' Concrete 0.95 Primary Treatment/StorageBasin V 2,547 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 2,830 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:07 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Dl 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 1,951 0 1,064 Acres 0.07 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.65 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.004 0.619 51 1.3 0.7 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 24 0.240 3.2 7.4 Computed Tc= 8.1 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.12 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 155 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 97 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 16 ft' Concrete 0.95 Primary Treatment/StorageBasin V 140 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 155 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:07 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN D2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 1,951 0 1,080 Acres 0.07 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.65 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.12 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 156 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 97 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 16 ft' Concrete 0.95 Primary Treatment/StorageBasin V 140 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 156 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:07 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Dl AND D2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 3,902 0 2,144 Acres 0.14 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.65 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.23 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 311 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 194 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 31 ft' Concrete 0.95 Primary Treatment/StorageBasin V 280 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 311 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:07 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN El 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 4,879 0 1,287 Acres 0.14 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.77 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.007 0.619 181 1.6 1.8 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 17 0.240 3.0 5.6 Computed Tc= 7.5 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.28 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 378 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) V,, 236 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 38 ft' Concrete 0.95 Primary Treatment/StorageBasin V 340 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 378 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:08 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN E2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 4,903 0 1,287 Acres 0.14 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.77 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.007 0.619 186 1.6 1.9 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 18 0.240 3.0 5.9 Computed Tc= 7.8 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.28 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 380 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) V,, 237 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 38 ft' Concrete 0.95 Primary Treatment/StorageBasin V 342 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 380 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:08 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�Mated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN El AND E2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 9,782 0 2,574 Acres 0.28 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.77 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.57 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 758 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 474 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 76 ft' Concrete 0.95 Primary Treatment/StorageBasin V 682 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 758 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:08 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �WPs for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASINS Dl,D2,El,AND E2-SEEPAGE BED 3 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 13,684 9,782 11,926 Acres 0.81 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.54 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning In Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(ClPeak) QPeak 1.13 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,514 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 946 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 151 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,363 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,514 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:09 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Fl 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 12,132 19,548 41 Acres 0.73 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.67 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.007 0.619 534 1.7 5.3 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 44 0.240 3.6 12.1 Computed Tc= 17.4 User-Entered Tc= 17.4 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.18 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 1.07 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,690 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,056 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 169 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,521 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,690 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:08 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN F2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 10,966 17,370 8,376 Acres 0.84 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.54 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 17.4 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.18 in/hr 9 Calculate the Post-Development peak discharge(ClPeak) Qpeak 1.00 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,582 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 989 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 158 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,424 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,582 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:09 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Fl AND F2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 23,098 36,918 8,417 Acres 1.57 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.60 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 17.4 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.18 in/hr 9 Calculate the Post-Development peak discharge(QPeak) QPeak 2.06 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 3,272 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 2,045 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 327 ft' Concrete 0.95 Primary Treatment/StorageBasin V 2,945 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 3,272 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:09 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-Gl 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 13,215 34,863 8,620 Acres 1.30 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.54 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.004 0.619 467 1.3 6.1 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 50 0.0 Computed Tc= 6.1 User-Entered Tc= 10.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 1.83 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 2,447 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,530 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 245 ft' Concrete 0.95 Primary Treatment/StorageBasin V 2,203 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 2,447 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:09 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-H1 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 6,627 11,485 Acres 0.42 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.66 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.010 0.619 268 2.0 2.2 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 45 0.240 3.7 12.3 Computed Tc= 14.5 User-Entered Tc= 14.5 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.71 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 955 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 597 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 96 ft' Concrete 0.95 Primary Treatment/StorageBasin V 860 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 955 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:10 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-H2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 7,162 8,739 5,473 Acres 0.49 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.55 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.010 0.619 286 2.0 2.3 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c 0.020 61 0.240 3.9 15.7 Computed Tc= 18.0 User-Entered Tc= 18.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.18 in/hr 9 Calculate the Post-Development peak discharge(QPeak) Qp,,k 0.59 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 930 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 581 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 93 ft' Concrete 0.95 Primary Treatment/StorageBasin V 837 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 930 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:10 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �W`s for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-H1 AND H2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 13,788 20,224 5,473 Acres 0.91 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.60 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 ruin. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( Business Downtown areas 0.70-0.95 Hydraulic Urban neighborhoods 0.50-0.70 Radius Flow Residential Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50 Multi-family 0.60-0.75 ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Residential(rural) 0.25-0.40 Segment 1:Pipe Flow Apartment Dwelling Areas 0.70 a Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Segment 2:Gutter Shallow Concentrated Flow Parks,Cemeteries 0.1010-0.25 b 0.619 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Segment 3:Overland Sheet Flow By TR-55,<300-ft c Computed Tc= 0.0 User-Entered Tc= 18.0 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.18 in/hr 9 Calculate the Post-Development peak discharge(ClPeak) Qpesk 1.19 cfs 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,885 ft3 V=Ci(Tc=60)Ax3600 11 Calculate Volume of Runoff Reduction Vrr Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,178 W 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 188 ft' Concrete 0.95 Primary Treatment/StorageBasin V 1,696 ft3 Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 1,885 ft3 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:10 AM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Steps for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name Drainage Basin 11 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) 2 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 2,399 6,145 5,868 1,343 Acres 0.36 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 0.35 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 1 0.41 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate to Min. Estimated Runoff Coefficients for Various Surface min - Type of Surface Runoff Coefficients"( 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) Qpe.k 0.38 cfs Urban neighborhoods 0.50-0.70 Residential Single Family 0.35-0.50 10 Calculate total runoff vol(V)(for sizing primary storage) V 508 ft3 Multi-family 0.60-0.75 V=CI(Tc=60)Ax3600 Residential(rural) 0.25-0.40 11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70 Industrial and Commercial Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Light areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) err 318 W Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,cemeteries 0. Playgrounds 0.20-0.0-0.35 5 Railroad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 51 ft' Concrete 0.95 Primary Treatment/StorageBasin V 458 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V SOS ftj Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 O. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_11-12 7/3/2025,3:03 PM Version 10.5,November 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. �WPs for Peak Discharge Rate using the Rational M�1171ated for post-developme Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name Drainage Basin 12 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 Click to Show More Subbasins C Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 664 4,653 7,182 Acres 0.29 6 Determine the Weighted Runoff Coefficient(C) 0.95 0.50 0.10 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.29 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 Min. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients N 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 n/hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) QPeak 0.22 cfs Urban neighborhoods 0.50-0.70 Residential Single Family 0.35-0.50 10 Calculate total runoff vol(V)(far sizing primary storage) V 292 fta Multi-family 0.60-0.75 V=CI(Tc=60)Ax3600 Residential(rural) 0.25-0.40 11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70 Industrial and Commercial Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Light areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vr, 182 ft' Heavy areas o.90 Parks,Cemeteries 0.10-0.25 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 0.95 Basin Forebay V 29 ft' Concrete 0.95 Primary Treatment/StorageBasin V 262 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 292 ft' Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 O. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 0. Adapted from ASCE P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_11-12 7/3/2025,3:05 PM Version 10.5,November 2018 INLET AND GUTTER CAPACITIES Hydraulic Analysis Report Project Data Project Title: 24-296 Pollard North No. 2 Designer:JAD/LCK Project Date:August 5, 2025 Project Units: U.S. Customary Units Notes: Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #1 (Basin Al) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: 0.0420 ft/ft Manning's n: 0.0170 Gutter Width: 1.5000 ft Gutter Result Parameters Design Flow: 0.1000 cfs Gutter Result Parameters Width of Spread: 3.1187 ft Gutter Depression: 0.3960 in Area of Flow: 0.1220 ft^2 Eo (Gutter Flow to Total Flow): 0.8895 Gutter Depth at Curb: 1.1445 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 45 degree tilt-bar w/2-1/4 in Grate Width: 1.5000 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in Inlet Result Parameters Perimeter: 5.3300 ft Effective Perimeter: 5.3300 ft Area: 1.1883 ft^2 Effective Area: 1.1883 ft^2 Depth at center of grate: 0.0339 ft Computed Width of Spread at Sag: 1.6222 ft Flow type:Weir Flow Efficiency: 1.0000 Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #2 (Basin 131) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: 0.0540 ft/ft Manning's n: 0.0170 Gutter Width: 1.1670 ft Gutter Result Parameters Design Flow: 1.4500 cfs Gutter Result Parameters Width of Spread: 9.8697 ft Gutter Depression: 0.4761 in Area of Flow: 0.9973 ft^2 Eo (Gutter Flow to Total Flow): 0.3219 Gutter Depth at Curb: 2.8449 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 45 degree tilt-bar w/2-1/4 in Grate Width: 1.1670 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in Inlet Result Parameters Perimeter: 4.6640 ft Effective Perimeter: 4.6640 ft Area: 0.9245 ft^2 Effective Area: 0.9245 ft^2 Depth at center of grate: 0.2206 ft Computed Width of Spread at Sag: 10.6229 ft Flow type:Weir Flow Efficiency: 1.0000 Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #3 (Basin 132) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: O.OS40 ft/ft Manning's n: 0.0170 Gutter Width: 1.1670 ft Gutter Result Parameters Design Flow: 1.4300 cfs Gutter Result Parameters Width of Spread: 9.8163 ft Gutter Depression: 0.4761 in Area of Flow: 0.9868 ft12 Eo (Gutter Flow to Total Flow): 0.3236 Gutter Depth at Curb: 2.8321 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 4S degree tilt-bar w/2-1/4 in Grate Width: 1.1670 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in inlet Kesuit Parameters Perimeter: 4.6640 ft Effective Perimeter: 4.6640 ft Area: 0.924S ft^2 Effective Area: 0.9245 ft^2 Depth at center of grate: 0.2186 ft Computed Width of Spread at Sag: 10.5212 ft Flow type:Weir Flow Efficiency: 1.0000 Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #4 (Basin E1) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: 0.0420 ft/ft Manning's n: 0.0170 Gutter Width: 1.5000 ft Gutter Result Parameters Design Flow: 0.2800 cfs Gutter Result Parameters Width of Spread: 4.6179 ft Gutter Depression: 0.3960 in Area of Flow: 0.2380 ft^2 Eo (Gutter Flow to Total Flow): 0.7219 Gutter Depth at Curb: 1.5043 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 45 degree tilt-bar w/2-1/4 in Grate Width: 1.5000 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in Inlet Result Parameters Perimeter: 5.3300 ft Effective Perimeter: 5.3300 ft Area: 1.1883 ft12 Effective Area: 1.1883 ft^2 Depth at center of grate: 0.0674 ft Computed Width of Spread at Sag: 3.2967 ft Flow type:Weir Flow Efficiency: 1.0000 Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #5 (Basin E2) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: 0.0420 ft/ft Manning's n: 0.0170 Gutter Width: 1.5000 ft Gutter Result Parameters Design Flow: 0.2800 cfs Gutter Result Parameters Width of Spread: 4.6179 ft Gutter Depression: 0.3960 in Area of Flow: 0.2380 ft^2 Eo (Gutter Flow to Total Flow): 0.7219 Gutter Depth at Curb: 1.5043 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 45 degree tilt-bar w/2-1/4 in Grate Width: 1.5000 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in Inlet Result Parameters Perimeter: 5.3300 ft Effective Perimeter: 5.3300 ft Area: 1.1883 ft^2 Effective Area: 1.1883 ft^2 Depth at center of grate: 0.0674 ft Computed Width of Spread at Sag: 3.2967 ft Flow type:Weir Flow Efficiency: 1.0000 Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #6 (Basin D1) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: 0.0420 ft/ft Manning's n: 0.0170 Gutter Width: 1.5000 ft Gutter Result Parameters Design Flow: 0.1200 cfs Gutter Result Parameters Width of Spread: 3.4191 ft Gutter Depression: 0.3960 in Area of Flow: 0.1417 ft^2 Eo (Gutter Flow to Total Flow): 0.8549 Gutter Depth at Curb: 1.2166 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 45 degree tilt-bar w/2-1/4 in Grate Width: 1.5000 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in Inlet Result Parameters Perimeter: 5.3300 ft Effective Perimeter: 5.3300 ft Area: 1.1883 ft^2 Effective Area: 1.1883 ft^2 Depth at center of grate: 0.0383 ft Computed Width of Spread at Sag: 1.8416 ft Flow type:Weir Flow Efficiency: 1.0000 Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #7 (Basin 132) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: 0.0420 ft/ft Manning's n: 0.0170 Gutter Width: 1.5000 ft Gutter Result Parameters Design Flow: 0.1200 cfs Gutter Result Parameters Width of Spread: 3.4191 ft Gutter Depression: 0.3960 in Area of Flow: 0.1417 ft^2 Eo (Gutter Flow to Total Flow): 0.8549 Gutter Depth at Curb: 1.2166 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 45 degree tilt-bar w/2-1/4 in Grate Width: 1.5000 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in Inlet Result Parameters Perimeter: 5.3300 ft Effective Perimeter: 5.3300 ft Area: 1.1883 ft12 Effective Area: 1.1883 ft^2 Depth at center of grate: 0.0383 ft Computed Width of Spread at Sag: 1.8416 ft Flow type:Weir Flow Efficiency: 1.0000 Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #8 (Basin F1) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: 0.0540 ft/ft Manning's n: 0.0170 Gutter Width: 1.1670 ft Gutter Result Parameters Design Flow: 1.0700 cfs Gutter Result Parameters Width of Spread: 7.9340 ft Gutter Depression: 0.4761 in Area of Flow: 0.6526 ft^2 Eo (Gutter Flow to Total Flow): 0.3967 Gutter Depth at Curb: 2.3803 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 45 degree tilt-bar w/2-1/4 in Grate Width: 1.1670 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in Inlet Result Parameters Perimeter: 4.6640 ft Effective Perimeter: 4.6640 ft Area: 0.9245 ft12 Effective Area: 0.9245 ft^2 Depth at center of grate: 0.1802 ft Computed Width of Spread at Sag: 8.5998 ft Flow type:Weir Flow Efficiency: 1.0000 Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #9 (Basin F2) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: 0.0540 ft/ft Manning's n: 0.0170 Gutter Width: 1.1670 ft Gutter Result Parameters Design Flow: 1.0000 cfs Gutter Result Parameters Width of Spread: 7.7227 ft Gutter Depression: 0.4761 in Area of Flow: 0.6196 ft^2 Eo (Gutter Flow to Total Flow): 0.4068 Gutter Depth at Curb: 2.3296 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 45 degree tilt-bar w/2-1/4 in Grate Width: 1.1670 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in Inlet Result Parameters Perimeter: 4.6640 ft Effective Perimeter: 4.6640 ft Area: 0.9245 ft^2 Effective Area: 0.9245 ft^2 Depth at center of grate: 0.1722 ft Computed Width of Spread at Sag: 8.2025 ft Flow type:Weir Flow Efficiency: 1.0000 Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #10 (Basin H1) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: 0.0540 ft/ft Manning's n: 0.0170 Gutter Width: 1.1670 ft Gutter Result Parameters Design Flow: 0.7100 cfs Gutter Result Parameters Width of Spread: 6.7266 ft Gutter Depression: 0.4761 in Area of Flow: 0.4756 ft^2 Eo (Gutter Flow to Total Flow): 0.4618 Gutter Depth at Curb: 2.0905 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 45 degree tilt-bar w/2-1/4 in Grate Width: 1.1670 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in Inlet Result Parameters Perimeter: 4.6640 ft Effective Perimeter: 4.6640 ft Area: 0.9245 ft^2 Effective Area: 0.9245 ft^2 Depth at center of grate: 0.1371 ft Computed Width of Spread at Sag: 6.4447 ft Flow type:Weir Flow Efficiency: 1.0000 Curb and Gutter Analysis: Curb and Gutter Analysis Inlet #11 (Basin 1­12) Notes: Gutter Input Parameters Longitudinal Slope of Road: 0.0000 ft/ft Cross-Slope of Pavement: 0.0200 ft/ft Depressed Gutter Geometry Cross-Slope of Gutter: 0.0420 ft/ft Manning's n: 0.0170 Gutter Width: 1.1670 ft Gutter Result Parameters Design Flow: 0.5900 cfs Gutter Result Parameters Width of Spread: 6.3480 ft Gutter Depression: 0.3081 in Area of Flow: 0.4180 ft^2 Eo (Gutter Flow to Total Flow): 0.4633 Gutter Depth at Curb: 1.8316 in Inlet Input Parameters Inlet Location: Inlet in Sag Percent Clogging: 0.0000 % Inlet Type: Grate Grate Type: 45 degree tilt-bar w/2-1/4 in Grate Width: 1.1670 ft Grate Length: 2.3300 ft Local Depression: 0.0000 in Inlet Result Parameters Perimeter: 4.6640 ft Effective Perimeter: 4.6640 ft Area: 0.9245 ft^2 Effective Area: 0.9245 ft^2 Depth at center of grate: 0.12 11 ft Computed Width of Spread at Sag: 5.9990 ft Flow type:Weir Flow Efficiency: 1.0000 Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Jul 7 2025 24-296 Basin C1 Triangular Highlighted Side Slopes (z:1) = 49.00, 52.00 Depth (ft) = 0.18 Total Depth (ft) = 0.20 Q (cfs) = 1.780 Area (sqft) = 1.64 Invert Elev (ft) = 100.00 Velocity (ft/s) = 1.09 Slope (%) = 0.42 Wetted Perim (ft) = 18.18 N-Value = 0.017 Crit Depth, Yc (ft) = 0.16 Top Width (ft) = 18.18 Calculations EGL (ft) = 0.20 Compute by: Known Q Known Q (cfs) = 1.78 Elev (ft) Section Depth (ft) 101.00 1.00 100.75 0.75 100.50 0.50 100.25 0.25 100.00 0.00 99.75 -0.25 0 5 10 15 20 25 30 35 Reach (ft) Inlet Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Jul 7 2025 Basin C1 - SGT #2 Drop Grate Inlet Calculations Location = Sag Compute by: Known Q Curb Length (ft) = -0- Q (cfs) = 1.78 Throat Height (in) = -0- Grate Area (sqft) = 3.00 Highlighted Grate Width (ft) = 1.50 Q Total (cfs) = 1.78 Grate Length (ft) = 2.00 Q Capt (cfs) = 1.78 Q Bypass (cfs) = -0- Gutter Depth at Inlet (in) = 2.31 Slope, Sw (ft/ft) = 0.020 Efficiency (%) = 100 Slope, Sx (ft/ft) = 0.020 Gutter Spread (ft) = 21.28 Local Depr (in) = -0- Gutter Vel (ft/s) = -0- Gutter Width (ft) = 2.00 Bypass Spread (ft) = -0- Gutter Slope (%) = -0- Bypass Depth (in) = -0- Gutter n-value = -0- r.11 dimensions Iniee[ 9.54 2.5D 9.54 Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Jul 7 2025 24-296 Basin G1 Triangular Highlighted Side Slopes (z:1) = 52.00, 49.00 Depth (ft) = 0.19 Total Depth (ft) = 0.20 Q (cfs) = 1.830 Area (sqft) = 1.82 Invert Elev (ft) = 100.00 Velocity (ft/s) = 1.00 Slope (%) = 0.40 Wetted Perim (ft) = 19.19 N-Value = 0.017 Crit Depth, Yc (ft) = 0.16 Top Width (ft) = 19.19 Calculations EGL (ft) = 0.21 Compute by: Known Q Known Q (cfs) = 1.83 Elev (ft) Section Depth (ft) 101.00 1.00 100.75 0.75 100.50 0.50 100.25 0.25 100.00 0.00 99.75 -0.25 0 5 10 15 20 25 30 35 Reach (ft) Inlet Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Jul 7 2025 Basin G1 - SGT #5 Drop Grate Inlet Calculations Location = Sag Compute by: Known Q Curb Length (ft) = -0- Q (cfs) = 1.83 Throat Height (in) = -0- Grate Area (sqft) = 3.00 Highlighted Grate Width (ft) = 1.50 Q Total (cfs) = 1.83 Grate Length (ft) = 2.00 Q Capt (cfs) = 1.83 Q Bypass (cfs) = -0- Gutter Depth at Inlet (in) = 2.36 Slope, Sw (ft/ft) = 0.020 Efficiency (%) = 100 Slope, Sx (ft/ft) = 0.020 Gutter Spread (ft) = 21.64 Local Depr (in) = -0- Gutter Vel (ft/s) = -0- Gutter Width (ft) = 2.00 Bypass Spread (ft) = -0- Gutter Slope (%) = -0- Bypass Depth (in) = -0- Gutter n-value = -0- r.11 dimensions Iniee[ 2 9.82 2.`J7 9.02 SEEPAGE BED CALCULATIONS ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Note this spreadsheet pulls information from the"Peak QV"tab Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN B3 AND B2-SEEPAGE BED#1 2 Enter number of Seepage Beds(25 max) 7 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.63 Linkto: QV QV2 — 5 Area A(Acres) 1.95 acres QV3 6 Approved discharge rate(if applicable) 0.00 cfs [Q,V4� QV5 _ 7 Is Seepage Bed in Common Lot? Yes V 4,210 ft3 0%Sediment 8 Set Total Design Width of All Drain Rock W 17.5 ft 9 Set Total Design Depth of All Drain Rock D 7.5 ft Rock Only,Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips 11 Design Infiltration Rate(8 in/hr max) Perc 8.00 in/hr 12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 360°),REQD if Q100>3.3 cfs in 14 Calculate Total Storage per Foot Spf 64.3 ft3/ft 15 Calculate Design Length L 65 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 65 ft 17 Variable Infiltration Window W SWW 17.5 ft 18 Time to Drain 5.0 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 65 ft 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAxV(2xgxH) Options Note:This assumes chambers are organized in a rectangular layout. 1-StormTech, 1 Type of Chambers SC740 2 Volume to Store V 0 ft3 3 Installed Chamber Width Cw 4.25 ft Installed Chamber Depth Cd 2.50 ft Installed Chamber Height Ch 7.12 ft 4 Chamber Void Factor 5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit 6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft'/Unit 7 Total Number of Units Required 0 ea 8 Area of Infiltration Aperc ft, 9 Volume Infiltration Vperc 0 ft3/hr 10 Time to Drain hours 90%volume in 48-hours minimum P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:21 AM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Note this spreadsheet pulls information from the"Peak Q,V"tab Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN C1-SEEPAGE BED#2 2 Enter number of Seepage Beds(25 max) 7 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.54 Link to: QV 5 Area A(Acres) 1.51 acres QV3 6 Approved discharge rate(if applicable) 0.00 cfs Q V4 [QV5� 7 Is Seepage Bed in Common Lot? Yes V 2,830 ft3 0%Sediment 8 Set Total Design Width of All Drain Rock W 15.0 ft 9 Set Total Design Depth of All Drain Rock D 7.5 ft Rock Only,Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips 11 Design Infiltration Rate(8 in/hr max) Perc 8.00 in/hr 12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 360°),RECID if Q100>3.3 cfs in 14 Calculate Total Storage per Foot Spf 55.2 ft3/ft 15 Calculate Design Length L 51 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 51 ft 17 Variable Infiltration Window W SWW 15.0 ft 18 Time to Drain 5.0 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 51 ft 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAxV(2xgxH) Optional Storage Chambers Note:This assumes chambers are organized in a rectangular layout. 1-StormTech, 1 Type of Chambers SC740 2 Volume to Store V 0 ft3 3 Installed Chamber Width Cw 4.25 ft Installed Chamber Depth Cd 2.50 ft Installed Chamber Height Ch 7.12 ft 4 Chamber Void Factor 5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit 6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit 7 Total Number of Units Required 0 ea 8 Area of Infiltration Aperc ft2 9 Volume Infiltration Vperc 0 ft3/hr 10 Time to Drain hours 90%volume in 48-hours minimum P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:21 AM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Note this spreadsheet pulls information from the"Peak QV"tab Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN Dl,D2,El,AND E2-SEEPAGE BED 3 2 Enter number of Seepage Beds(25 max) 7 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.54 Unkto: QVts 5 Area A(Acres) 0.81 acres [QV20� 6 Approved discharge rate(if applicable) 0.00 cfs QVTa55 _ 7 Is Seepage Bed in Common Lot? No 1,893 ft3 25%Sediment 8 Set Total Design Width of All Drain Rock W 15.0 ft 9 Set Total Design Depth of All Drain Rock D 7.5 ft Rock Only,Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips 11 Design Infiltration Rate(8 in/hr max) Perc 8.00 in/hr 12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 360°),RECID if Q100>3.3 cfs in 14 Calculate Total Storage per Foot Spf 55.2 ft3/ft 15 Calculate Design Length L 34 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 34 ft 17 Variable Infiltration Window W SWW 15.0 ft 18 Time to Drain 5.0 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 34 ft 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAxV(2xgxH) Optional Storage Chambers Note:This assumes chambers are organized in a rectangular layout. 1-StormTech, 1 Type of Chambers SC740 2 Volume to Store V 0 ft3 3 Installed Chamber Width Cw 4.25 ft Installed Chamber Depth Cd 2.50 ft Installed Chamber Height Ch 7.12 ft 4 Chamber Void Factor 5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit 6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit 7 Total Number of Units Required 0 ea 8 Area of Infiltration Aperc ft2 9 Volume Infiltration Vperc 0 ft3/hr 10 Time to Drain hours 90%volume in 48-hours minimum P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025.xlsm 8/5/2025,4:41 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Note this spreadsheet pulls information from the"Peak QV"tab Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASINS Fl AND F2-SEEPAGE BED#4 2 Enter number of Seepage Beds(25 max) 7 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.60 Unkto: Qvio ' Qv11 5 Area A(Acres) 1.57 acres QV12 6 Approved discharge rate(if applicable) 0.00 cfs QV13 7 Is Seepage Bed in Common Lot? No 4,090 ft3 25%Sediment 8 Set Total Design Width of All Drain Rock W 10.0 ft 9 Set Total Design Depth of All Drain Rock D 7.5 ft Rock Only,Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips 11 Design Infiltration Rate(8 in/hr max) Perc 8.00 in/hr 12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 360°),REQD if Q100>3.3 cfs in 14 Calculate Total Storage per Foot Spf 36.8 ft3/ft 15 Calculate Design Length L 111 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 111 ft 17 Variable Infiltration Window W SWW 10.0 ft 18 Time to Drain 5.0 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 111 ft 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAxV(2xgxH) Optional Storage Chambers Note:This assumes chambers are organized in a rectangular layout. 1-StormTech, 1 Type of Chambers SC740 2 Volume to Store V 0 ft3 3 Installed Chamber Width Cw 4.25 ft Installed Chamber Depth Cd 2.50 ft Installed Chamber Height Ch 7.12 ft 4 Chamber Void Factor 5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit 6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit 7 Total Number of Units Required 0 ea 8 Area of Infiltration Aperc ft2 9 Volume Infiltration Vperc 0 ft3/hr 10 Time to Drain hours 90%volume in 48-hours minimum P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025.xlsm 8/5/2025,4:43 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Note this spreadsheet pulls information from the"Peak Q,V"tab Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN G3-SEEPAGE BED 5 2 Enter number of Seepage Beds(25 max) 7 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.54 Link to: [Qv15 � 5 Area A(Acres) 1.30 acres QV16 6 Approved discharge rate(if applicable) 0.00 cfs QV17 QV18 _ 7 Is Seepage Bed in Common Lot? Yes 2,447 ft3 0%Sediment 8 Set Total Design Width of All Drain Rock W 12.0 ft 9 Set Total Design Depth of All Drain Rock D 7.5 ft Rock Only,Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips 11 Design Infiltration Rate(8 in/hr max) Perc 8.00 in/hr 12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 360°),REQD if Q100>3.3 cfs in 14 Calculate Total Storage per Foot Spf 44.2 ft3/ft 15 Calculate Design Length L 55 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 55 ft 17 Variable Infiltration Window W SWW 12.0 ft 18 Time to Drain 5.0 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 55 ft 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAxV(2xgxH) Ir Optional Storage Chambers Note:This assumes chambers are organized in a rectangular layout. 1-StormTech, 1 Type of Chambers SC740 2 Volume to Store V 0 ft3 3 Installed Chamber Width Cw 4.25 ft Installed Chamber Depth Cd 2.50 ft Installed Chamber Height Ch 7.12 ft 4 Chamber Void Factor 5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit 6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit 7 Total Number of Units Required 0 ea 8 Area of Infiltration Aperc ft2 9 Volume Infiltration Vperc 0 ft3/hr 10 Time to Drain hours 90%volume in 48-hours minimum P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025 6/24/2025,9:22 AM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Note this spreadsheet pulls information from the"Peak QV"tab Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH q2-BASINS H3 AND H2-SEEPAGE BED 6 2 Enter number of Seepage Beds(25 max) 7 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.65 Link to: QV16 5 Area A(Acres) 0.79 acres 1QV78� 6 Approved discharge rate(if applicable) 0.00 cfs Q'V19 — QV20 _ 7 Is Seepage Bed in Common Lot? Yes V 1,769 ft3 0%Sediment 8 Set Total Design Width of All Drain Rock W 15.0 ft 9 Set Total Design Depth of All Drain Rock D 7.5 ft Rock Only,Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips 11 Design Infiltration Rate(8 in/hr max) Perc 8.00 in/hr 12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 360°),REQD if Q100>3.3 cfs in 14 Calculate Total Storage per Foot Spf 55.2 ft3/ft 15 Calculate Design Length L 32 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 32 ft 17 Variable Infiltration Window W SWW 15.0 ft 18 Time to Drain 5.0 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 32 ft 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAxV(2xgxH) Note:This assumes chambers are organized in a rectangular layout. 1-StormTech, 1 Type of Chambers SC740 2 Volume to Store V 0 ft3 3 Installed Chamber Width Cw 4.25 ft Installed Chamber Depth Cd 2.50 ft Installed Chamber Height Ch 7.12 ft 4 Chamber Void Factor 5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit 6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit 7 Total Number of Units Required 0 ea 8 Area of Infiltration Aperc ft, 9 Volume Infiltration Vperc 0 ft3/hr 10 Time to Drain hours 90%volume in 48-hours minimum P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025.xlsm 8/5/2025,4:44 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Note this spreadsheet pulls information from the"Peak Q,V"tab Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN 11-SEEPAGE BED 7 2 Enter number of Seepage Beds(25 max) 2 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.41 Link to: LQV QV2 - 5 Area A(Acres) 0.36 acres QV TR55 6 Approved discharge rate(if applicable) 0.00 cfs 7 Is Seepage Bed in Common Lot? Yes 508 ft3 0%Sediment 8 Set Total Design Width of All Drain Rock W 12.0 ft 9 Set Total Design Depth of All Drain Rock D 7.5 ft Rock Only,Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips 11 Design Infiltration Rate(8 in/hr max) Perc 8.00 in/hr 12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 360°),REQD if Q100>3.3 cfs in 14 Calculate Total Storage per Foot Spf 44.2 ft3/ft 15 Calculate Design Length L 12 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 12 ft 17 Variable Infiltration Window W SWW 12.0 ft 18 Time to Drain 5.0 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 12 ft 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAxV(2xgxH) Optional Storage Chambers Note:This assumes chambers are organized in a rectangular layout. 1-StormTech, 1 Type of Chambers SC740 2 Volume to Store V 0 ft3 3 Installed Chamber Width Cw 4.25 ft Installed Chamber Depth Cd 2.50 ft Installed Chamber Height Ch 7.12 ft 4 Chamber Void Factor 5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit 6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit 7 Total Number of Units Required 0 ea 8 Area of Infiltration Aperc ft2 9 Volume Infiltration Vperc 0 ft3/hr 10 Time to Drain hours 90%volume in 48-hours minimum P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_I1-12 7/3/2025,3:07 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Note this spreadsheet pulls information from the"Peak Q,V"tab Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name POLLARD NORTH#2-BASIN 12-SEEPAGE BED 8 2 Enter number of Seepage Beds(25 max) 2 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.29 Link to: QV [QV2� 5 Area A(Acres) 0.29 acres QV TR55 6 Approved discharge rate(if applicable) 0.00 cfs 7 Is Seepage Bed in Common Lot? Yes 292 ft3 0%Sediment 8 Set Total Design Width of All Drain Rock W 9.0 ft 9 Set Total Design Depth of All Drain Rock D 7.5 ft Rock Only,Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips 11 Design Infiltration Rate(8 in/hr max) Perc 8.00 in/hr 12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 360°),RECID if Q100>3.3 cfs in 14 Calculate Total Storage per Foot Spf 33.2 ft3/ft 15 Calculate Design Length L 9 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 9 ft 17 Variable Infiltration Window W SWW 9.0 ft 18 Time to Drain 5.0 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 9 ft 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAxV(2xgxH) Optional Storage Chambers Note:This assumes chambers are organized in a rectangular layout. 1-StormTech, 1 Type of Chambers SC740 2 Volume to Store V 0 ft3 3 Installed Chamber Width Cw 4.25 ft Installed Chamber Depth Cd 2.50 ft Installed Chamber Height Ch 7.12 ft 4 Chamber Void Factor 5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit 6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit 7 Total Number of Units Required 0 ea 8 Area of Infiltration Aperc ft2 9 Volume Infiltration Vperc 0 ft3/hr 10 Time to Drain hours 90%volume in 48-hours minimum P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_I1-12 7/3/2025,3:08 PM Version 10.5,November 2018 INFILTRATION BASIN CALCULATIONS ACHD Calculation Sheet for Sizing Basins NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. User input in yellow cells. 1 Project Name POLLARD NORTH rig-BASIN Al(POND Nl) 2 Enter number of Basins(25 max) 1 3 Number of Cells(Forebay+primary=2,Primary Only=1) 1 4 Design Storm 100 Q,v 5 Weighted Runoff Coefficient C 0.57 QVz QV3 6 Area A(Acres) 0.07 acres QV4 0.00 cfs Qvs 7 Approved Discharge Rate(if applicable) QV6 8 2-Primary Treatment/Storage V 131 ft3 QV7 Q Va Toggle between Forebay and Primary Basin,enter data and print for each *S*8*Z FWw n- Aww <---- < L i mks*z ! L �. side s1w. Primary Basin 9 Select Primary Basin Shape 3-Rectangle 10 Width of Primary Basin Bottom W 2.0 ft 11 Length of Primary Basin Bottom L 25.0 ft 12 Side Slopes(H:1) HA 3.00 13 Enter Bottom Elevation 2528.00 ft 14 Enter Top Bank Elevation 2530.00 ft 15 Enter Water Surface Elevation(WSE) 2529.50 ft 16 Distance Between Forebay and Primary Basin(blank if na) 0.00 ft 17 Enter Elevation Berm 0.00 ft 18 Enter High Groundwater Elevation 2517.00 ft 19 Min.Freeboard Requirement 0.50 20 Freeboard Provided 21 Infiltration Area for Primary/Storage Basin Infiltration? 8.00 in/hr Note:infiltration required if Design Infiltration Rate,Enter 0 for no infiltration bottom slope<1%or 0 outflow 22 Infiltration Area for Primary Asand 10 ftZ Enter 0 for no infiltration 23 Adjusted Storage Required Storm Duration i total Q Runoff Vol Perc Vol Pre-Dev Total je ol Discharge Discharge Min Hr in/hr cfs ft3 ft3 ft3 ft3 60 1.00 0.96 0.04 131 7 0 7 24 Depth-Storage Relationship: Saved Surface Basin Basin Surface Surface Area A at Volume Saved Stage Side Slope Width at Length at Area A at Area A at Stage(ft) Below Stage (ft) New Stage(ft) (H:V) Stage(ft) Stage(ft) Stage(ft) Stage(ft) OVERIDE (ft) 2528.00 2528.00 3.000 2.0 25.0 50 0 2529.00 2529.00 3.000 8.0 31.0 248 149 2529.50 1 2529.50 3.000 1 11.0 34.0 1 374 1 305 1.50 ft depth for storage STORAGE OK 25 Does primary/storage basin have capacity? 26 Time to drain primary/storage basin 17.7 hours 90%volume in 48-hours minimum - P:\24-296\Civil\Calculations&Reports\Storm Drainage\Calcs\ACHD_SD_CALCS_062025.xlsm 8/5/2025,4:39 PM Version 10.5,November 2018 APPENDIX D - GEOTECHNICAL ENGINEERING REPORT & GROUNDWATER DATA POLLARD LANE REALIGNMENT (MTI, 8/31/2016) MATERIALS %IWTESTI NG & INSPECTION ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GEOTECHNICAL ENGINEERING REPORT of Pollard lane Realignment Pollard Lane & Chinden Boulevard Meridian, ID Prepared for: Brighton Corporation 12601 West Explore Drive, Suite 200 Boise, ID 83713 MTI File Number B161073g 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 www.mti-id.com •mtiCcDmti-id.com MATERIALS 31 August 2016 TESTI NG & Page 9 l of 26 INSPECTION b161073g geotechdoex ❑ Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections Mr. Jon Wardle Brighton Corporation 12601 West Explore Drive, Suite 200 Boise, ID 83713 208-378-4000 Re: Geotechnical Engineering Report Pollard Lane Realignment Pollard Lane & Chinden Boulevard Meridian, ID Dear Mr. Wardle: In compliance with your instructions, MTI has conducted a soils exploration and pavement evaluation for the above referenced development. Fieldwork for this investigation was conducted on 19 August 201.6. Data have been analyzed to evaluate pertinent geotechnical conditions. Results of this investigation, together with our recommendations, are to be found in the following report. We have provided a PDF copy for your review and distribution. Often, questions arise concerning soil conditions because of design and construction details that occur on a project. MTI would be pleased to continue our role as geotechnical engineers during project implementation. Additionally, MTI can provide materials testing and special inspection services during construction of this project. If you will advise us of the appropriate time to discuss these engineering services, we will meet with you at your convenience. MTI appreciates this opportunity to be of service to you and looks forward to working with you in the future. If you have questions, please call (208) 376-4748. Respectfully Submitted, Materials Testing & Inspection, Inc. 5510NAL ��c�NSFA 14919 Jacob Schlador, E.I.T. Reviewed by: Monica Sac es, P. Staff Engineer Geotechnical Enginee ?����TF�F 10 3AC���� 64.— Reviewed by: Eli abeth Brown, P.E. Geotechnical Engineer 2791 S Victory View Way- Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKalmti-id.com MATERIALS 31 August2016 TESTI NG & Page# 2 of 26 INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections TABLE OF CONTENTS INTRODUCTION...............................................................................................................................................................3 ProjectDescription.................................................................................................................................................3 Authorization..........................................................................................................................................................3 Purpose...................................................................................................................................................................3 Scopeof Investigation............................................................................................................................................3 Warrantyand Limiting Conditions.........................................................................................................................4 SITEDESCRIPTION..........................................................................................................................................................5 SiteAccess..............................................................................................................................................................5 RegionalGeology...................................................................................................................................................5 GeneralSite Characteristics....................................................................................................................................5 Regional Site Climatology and Geochemistry........................................................................................................6 SomsEXPLORATION......................................................................................................................................................6 Exploration and Sampling Procedures....................................................................................................................6 Laboratory Testing Program...................................................................................................................................6 Soiland Sediment Profile.......................................................................................................................................7 VolatileOrganic Scan.............................................................................................................................................7 SITEHYDROLOGY...........................................................................................................................................................7 Groundwater...........................................................................................................................................................7 SoilInfiltration Rates..............................................................................................................................................8 PAVEMENT DISCUSSION AND RECOMMENDATIONS........................................................................................................8 RecommendedPavement Sections.........................................................................................................................8 FlexiblePavement Section.....................................................................................................................................9 Common Pavement Section Construction Issues ...................................................................................................9 CONSTRUCTION CONSIDERATIONS...............................................................................................................................10 Earthwork.............................................................................................................................................................10 DryWeather.........................................................................................................................................................11 WetWeather.........................................................................................................................................................11 SoftSubgrade Soils ..............................................................................................................................................11 FrozenSubgrade Soils..........................................................................................................................................12 StructuralFill........................................................................................................................................................12 Excavations...........................................................................................................................................................13 GroundwaterControl............................................................................................................................................13 GENERALCOMMENTS..................................................................................................................................................14 REFERENCES.................................................................................................................................................................15 APPENDICES.................................................................................................................................................................16 AcronymList........................................................................................................................................................16 GeotechnicalGeneral Notes.................................................................................................................................17 Geotechnical Investigation Test Pit Log...............................................................................................................18 Gravel Equivalent Method—Pavement Thickness Design Procedures................................................................23 R-Value Laboratory Test Data..............................................................................................................................24 Plate1:Vicinity Map............................................................................................................................................25 Plate2: Site Map...................................................................................................................................................26 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August 2016 TESTI NG & Page# 3 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections INTRODUCTION This report presents results of a geotechnical investigation and analysis in support of data utilized in design of pavements as defined in the Idaho Standard for Public Works Construction. Information in support of groundwater and stormwater issues pertinent to the practice of Civil Engineering is included. Observations and recommendations relevant to the earthwork phase of the project are also presented. Revisions in plans or drawings for the proposed development from those enumerated in this report should be brought to the attention of the soils engineer to determine whether changes in the provided recommendations are required. Deviations from noted subsurface conditions, if encountered during construction, should also be brought to the attention of the soils engineer. Project Description The proposed development is northwest of the City of Meridian, Ada County, ID, and occupies a portion of the SEl/4SW1/4 and SW1/4SE'/4 of Section 21, Township 4 North, Range 1 West, Boise Meridian. This project will consist of relocating a portion of Pollard Lane to align with Levi Lane on the south side of Chinden Boulevard. The proposed roadway section will be roughly 0.35 mile in length. At this time, barrow ditches are planned for the sides of the rural roadway. Assumptions have been made for traffic loading of pavements. Retaining walls are not anticipated as part of the project. MTI has not been informed of the proposed grading plan. Authorization Authorization to perform this exploration and analysis was given in the form of a written authorization to proceed from Mr. Jon Wardle of Brighton Corporation to Monica Saculles of Materials Testing and Inspection, Inc. (MTI), on 10 August 2016. Said authorization is subject to terms, conditions, and limitations described in the Professional Services Contract entered into between Brighton Corporation and MTI. Our scope of services for the proposed development has been provided in our proposal dated 10 August 2016 and repeated below. Purpose The purpose of this Geotechnical Engineering Report is to determine various soil profile components and their engineering characteristics for use by either design engineers or architects in: • Preparing site drainage designs • Indicating issues pertaining to earthwork construction • Preparing rural roadway pavement section design requirements Scope of Investigation The scope of this investigation included review of geologic literature and existing available geotechnical studies of the area, visual site reconnaissance of the immediate site, subsurface exploration of the site, field and laboratory testing of materials collected, and engineering analysis and evaluation of pavement materials. Our scope of work did not include foundation recommendations. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing 2016 Materials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 4 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections Warranty and Limiting Conditions MTI warrants that findings and conclusions contained herein have been formulated in accordance with generally accepted professional engineering practice in the fields of foundation engineering, soil mechanics, and engineering geology only for the site and project described in this report. These engineering methods have been developed to provide the client with information regarding apparent or potential engineering conditions relating to the site within the scope cited above and are necessarily limited to conditions observed at the time of the site visit and research. Field observations and research reported herein are considered sufficient in detail and scope to form a reasonable basis for the purposes cited above. Exclusive Use This report was prepared for exclusive use of the property owner(s), at the time of the report, and their retained design consultants ("Client"). Conclusions and recommendations presented in this report are based on the agreed-upon scope of work outlined in this report together with the Contract for Professional Services between the Client and Materials Testing and Inspection, Inc. ("Consultant"). Use or misuse of this report, or reliance upon findings hereof, by parties other than the Client is at their own risk. Neither Client nor Consultant make representation of warranty to such other parties as to accuracy or completeness of this report or suitability of its use by such other parties for purposes whatsoever, known or unknown, to Client or Consultant. Neither Client nor Consultant shall have liability to indemnify or hold harmless third parties for losses incurred by actual or purported use or misuse of this report. No other warranties are implied or expressed. Report Recommendations are Limited and Subiect to Misinterpretation There is a distinct possibility that conditions may exist that could not be identified within the scope of the investigation or that were not apparent during our site investigation. Findings of this report are limited to data collected from noted explorations advanced and do not account for unidentified fill zones, unsuitable soil types or conditions, and variability in soil moisture and groundwater conditions. To avoid possible misinterpretations of findings, conclusions, and implications of this report, MTI should be retained to explain the report contents to other design professionals as well as construction professionals. Since actual subsurface conditions on the site can only be verified by earthwork, note that construction recommendations are based on general assumptions from selective observations and selective field exploratory sampling. Upon commencement of construction, such conditions may be identified that require corrective actions, and these required corrective actions may impact the project budget. Therefore, construction recommendations in this report should be considered preliminary, and MTI should be retained to observe actual subsurface conditions during earthwork construction activities to provide additional construction recommendations as needed. Since geotechnical reports are subject to misinterpretation, do not separate the soil logs from the report. Rather, provide a copy of, or authorize for their use, the complete report to other design professionals or contractors. Locations of exploratory sites referenced within this report should be considered approximate locations only. For more accurate locations, services of a professional land surveyor are recommended. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 5 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections This report is also limited to information available at the time it was prepared. In the event additional information is provided to MTI following publication of our report, it will be forwarded to the client for evaluation in the form received. Environmental Concerns Comments in this report concerning either onsite conditions or observations, including soil appearances and odors, are provided as general information. These comments are not intended to describe, quantify, or evaluate environmental concerns or situations. Since personnel, skills, procedures, standards, and equipment differ, a geotechnical investigation report is not intended to substitute for a geoenvironmental investigation or a Phase 11/III Environmental Site Assessment. If environmental services are needed, MTI can provide, via a separate contract, those personnel who are trained to investigate and delineate soil and water contamination. SITE DESCRIPTION Site Access Access to the site may be gained via Interstate 84 to the Ten Mile Road exit. Proceed north on Ten Mile Road approximately 4.7 miles to its intersection with Highway 20/26. From this intersection, proceed west 1.7 miles to its intersection with Pollard Lane. The site occupies the northeast corner of this intersection. Presently the site exists as an agricultural field. The location is depicted on site map plates included in the Appendix. Regional Geology The project site is located within the western Snake River Plain of southwestern Idaho and eastern Oregon. The plain is a northwest trending rift basin, about 45 miles wide and 200 miles long, that developed about 14 million years ago (Ma) and has since been occupied sporadically by large inland lakes. Geologic materials found within and along the plain's margins reflect volcanic and fluvial/lacustrine sedimentary processes that have led to an accumulation of approximately 1 to 2 km of interbedded volcanic and sedimentary deposits within the plain. Along the margins of the plain, streams that drained the highlands to the north and south provided coarse to fine-grained sediments eroded from granitic and volcanic rocks, respectively. About 2 million years ago the last of the lakes was drained and since that time fluvial erosion and deposition has dominated the evolution of the landscape. The project site is underlain by the "Gravel of Whitney Terrace" as mapped by Othberg and Stanford (1993). Sediments of the Whitney terrace consist of sandy pebble and cobble gravel. The Whitney terrace is the second terrace above modern Boise River floodplain, is thickest toward its eastern extent, and is mantled with 2-6 feet of loess. General Site Characteristics This proposed development consists of an approximately 0.35 mile length of proposed roadway that is relatively flat and level terrain. Throughout the majority of the site, surficial soils consist of fine-grained silt soils. Vegetation primarily consists of onions at the time of the investigation. An irrigation ditch runs through the southern boundary of the project site. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 6 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections Regional drainage is north and west toward the Boise River. Stormwater drainage for the site is achieved by percolation through surficial soils. The site is situated so that it is unlikely that it will receive any stormwater drainage from off-site sources. Stormwater drainage collection and retention systems are not in place on the project site and were not noted within the vicinity of the project site. Regional Site Climatology and Geochemistry According to the Western Regional Climate Center, the average precipitation for the Treasure Valley is on the order of 10 to 12 inches per year, with an annual snowfall of approximately 20 inches and a range from 3 to 49 inches. The monthly mean daily temperatures range from 21°F to 95°F, with daily extremes ranging from -25°F to I I I'F. Winds are generally from the northwest or southeast with an annual average wind speed of approximately 9 miles per hour (mph) and a maximum of 62 mph. Soils and sediments in the area are primarily derived from siliceous materials and exhibit low electro-chemical potential for corrosion of metals or concretes. Local aggregates are generally appropriate for Portland cement and lime cement mixtures. Surface water, groundwater, and soils in the region typically have pH levels ranging from 7.2 to 8.2. SOILS EXPLORATION Exploration and Sampling Procedures Field exploration conducted to determine engineering characteristics of subsurface materials included a reconnaissance of the project site and investigation by test pit. Test pits were located in the field by a representative of Brighton Corporation prior to MTI's arrival on the site and Global Positioning System(GPS) device was used to obtain longitude and latitude of test pit sites and are reportedly accurate to within ten feet. Upon completion of investigation, each test pit was backfilled with loose excavated materials. Re-excavation and compaction of these test pit areas are required prior to construction of overlying structures. In addition, samples were obtained from representative soil strata encountered. Samples obtained have been visually classified in the field by professional staff, identified according to test pit number and depth, placed in sealed containers, and transported to our laboratory for additional testing. Subsurface materials have been described in detail on logs provided in the Appendix. Results of field and laboratory tests are also presented in the Appendix. MTI recommends that these logs not be used to estimate fill material quantities. Laboratory Testing Program Along with our field investigation, a supplemental laboratory testing program was conducted to determine additional pertinent engineering characteristics of subsurface materials necessary in an analysis of anticipated behavior of the proposed structures. Laboratory tests were conducted in accordance with current applicable American Society for Testing and Materials (ASTM) specifications, and results of these tests are to be found on the accompanying logs located in the Appendix. The laboratory testing program for this report included: Atterberg Limits Testing — ASTM D4318, Grain Size Analysis — ASTM C 117/C 136, and Resistance Value (R-value) and Expansion Pressure of Compacted Soils—Idaho T-8. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 7 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections Soil and Sediment Profile The profile below represents a generalized interpretation for the project site. Note that on site soils strata, encountered between test pit locations, may vary from the individual soil profiles presented in the logs, which can be found in the Appendix. The materials encountered during exploration were quite typical for the geologic area mapped as Gravel of Whitney Terrace. Surficial soils were predominately silt with sand and sandy silt soils. Silts with sand and sandy silts were dark brown to brown, dry to slightly moist, stiff to hard, and contained fine-grained sand. In test pit 5, silty sand with gravel fills were encountered at ground surface. Silty sand with gravel fills were light brown to brown, dry, medium dense to dense, and contained fine to coarse-grained sand. Plow zones/disturbed zones should be expected throughout the length of the roadway. Actual depths of these zones are unknown at this time since test pits were kept to the edges of the crops. Underlying the silts with sand and sandy silts were silty sand sediments. Silty sands were brown to light brown, dry to slightly moist, dense to very dense, and contained fine to medium-grained sand and varying degrees of calcium carbonate cementation and induration. At depth in all the test pits were poorly graded gravel with sand sediments. Poorly graded gravels were light brown, dry to saturated, medium dense to dense, and contained fine to coarse-grained sand, fine to coarse gravel, and 6-inch-minus cobbles. Competency of test pit walls varied little across the site. In general, fine grained soils remained stable while more granular sediments readily sloughed. However, moisture contents will also affect wall competency with saturated soils having a tendency to readily slough when under load and unsupported. Volatile Organic Scan No environmental concerns were identified prior to commencement of the investigation. Therefore, soils obtained during on-site activities were not assessed for volatile organic compounds by portable photoionization detector. Samples obtained during our exploration activities exhibited no odors or discoloration typically associated with this type of contamination. Groundwater encountered did not exhibit obvious signs of contamination. SITE HYDROLOGY Existing surface drainage conditions are defined in the General Site Characteristics section. Information provided in this section is limited to observations made at the time of the investigation. Either regional or local ordinances may require information beyond the scope of this report. Groundwater During this field investigation, groundwater was encountered in test pit 5 at a depth of 15.2 feet bgs. Soil moistures in the test pits were generally dry to slightly moist within surficial soils. Within the poorly graded gravels, soil moistures graded from dry to saturated as the water table was approached and penetrated. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 8 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections In the vicinity of the project site, groundwater levels are controlled in large part by residential and aggricultural irrigation activity and leakage from nearby irrigation ditches and canals. Maximum groundwater elevations likely occur during the later portion of the irrigation season. During previous investigations performed in September 2011 and May 2013 within approximately 1/2-mile to the east and northeast of the project site, no evidence of groundwater was noted within test pits advanced to depths as great as 13.5 to 15.0 feet bgs. Furthermore, according to United States Geological Survey (USGS) monitoring well data within approximately 1/2-mile of the project site, groundwater was measured at depths ranging between 20 and 30 feet bgs. Based on evidence of this investigation and background knowledge of the area, MTI estimates groundwater depths to remain greater than approximately 13 feet bgs throughout the year. This depth can be confirmed through long-term groundwater monitoring. Soil Infiltration Rates Soil permeability, which is a measure of the ability of a soil to transmit a fluid, was not tested in the field. Given the absence of direct measurements, for this report an estimation of infiltration is presented using generally recognized values for each soil type and gradation. Of soils comprising the generalized soil profile for this study, silt with sand soils generally offer little permeability, with typical hydraulic infiltration rates of less than 2 inches per hour. Sandy silt soils will commonly exhibit infiltration rates from 2 to 4 inches per hour and silty sand sediments usually display rates of 4 to 8 inches per hour; though calcium carbonate cementation and induration may reduce these values to near zero. Poorly graded gravel sediments typically exhibit infiltration values in excess of 12 inches per hour. Infiltration testing is generally not required within these sediments because of their free-draining nature. PAVEMENT DISCUSSION AND RECOMMENDATIONS Recommended Pavement Sections As required by Ada County Highway District (ACHD), MTI has used a traffic index of 6 to determine the necessary pavement cross-section for the site. MTI has made assumptions for traffic loading variables based on the character of the proposed construction. The Client should review these assumptions to make sure they reflect intended use and loading of pavements both now and in the future. MTI collected a sample of near- surface soils for Resistance Value (R-value) testing representative of soils to depths of 2 feet below existing ground surface. This sample, consisting of sandy silt collected from test pit 4, yielded a R-value of 12. The following are minimum thickness requirements for assured pavement function. Depending on site conditions, additional work, e.g. soil preparation, may be required to support construction equipment. These have been listed within the Soft Subgrade Soils section. Results of the test are graphically depicted in the Appendix. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 9 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections Flexible Pavement Section The Gravel Equivalent Method, as defined in Section 500 of the State of Idaho Department of Transportation (ITD) Materials Manual, was used to develop the pavement sections. ACHD parameters for traffic index and substitution ratios, which were obtained from the ACHD Policy Manual, were also used in the design. Calculation sheet provided in the Appendix indicate the soils constant, traffic loading, traffic projections, and material constants used to calculate the pavement sections. MTI recommends that materials used in the construction of asphaltic concrete pavements meet the requirements of the ISPWC Standard Specification for Highway Construction. Construction of the pavement section should be in accordance with these specifications and should adhere to guidelines recommended in the section on Construction Considerations. Gravel Equivalent Method Flexible Pavement Specifications Pavement Section Component' Roadway Section Asphaltic Concrete 2.5 Inches Crushed Aggregate Base 4.0 Inches Structural Subbase 12.0 Inches Not Required for Native Soils Compacted Subgrade' 12.0 Inches to 95% of ASTM D698 for Existing Fill Materials/Plow Zones 'It will be required for MTI personnel to verify subgrade competency at the time of construction. 2Depending on the time of year construction takes place, the subgrade soils may be unstable because of high moisture contents. If unstable conditions are encountered, over-excavation and replacement with granular structural fill and/or use of geotextiles ma,, b�quired. Asphaltic Concrete: Asphalt mix design shall meet the requirements of ISPWC, Section 810 Class III plant mix. Materials shall be placed in accordance with ISPWC Standard Specifications for Highway Construction. Aggregate Base: Material complying with ISPWC Standards for Crushed Aggregate Materials. Structural Subbase: Material complying with requirements for granular structural fill (uncrushed) as defined in ISPWC. Common Pavement Section Construction Issues The subgrade upon which above pavement sections are to be constructed must be properly stripped, inspected, and proof-rolled. Proof rolling of subgrade soils should be accomplished using a heavy rubber-tired, fully loaded, tandem-axle dump truck or equivalent. Verification of subgrade competence by MTI personnel at the time of construction is required. Fill materials on the site must demonstrate the indicated compaction prior to placing material in support of the pavement section. MTI anticipated that pavement areas will be subjected to moderate traffic. MTI does not anticipate pumping material to become evident during compaction, but subgrade clays and silts near and above optimum moisture contents may tend to pump. Pumping or soft areas must be removed and replaced with structural fill. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 10 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections Fill material and aggregates in support of the pavement section must be compacted to no less than 95 percent of the maximum dry density as determined by ASTM D698 for flexible pavements and by ASTM D1557 for rigid pavements. If a material placed as a pavement section component cannot be tested by usual compaction testing methods, then compaction of that material must be approved by observed proof rolling. Minor deflections from proof rolling for flexible pavements are allowable. Deflections from proof rolling of rigid pavement support courses should not be visually detectable. MTI recommends that rigid concrete pavement be provided for heavy garbage receptacles. This will eliminate damage caused by the considerable loading transferred through the small steel wheels onto asphaltic concrete. Rigid concrete pavement should consist of Portland Cement Concrete Pavement (PCCP) generally adhering to ITD specifications for Urban Concrete. PCCP should be 6 inches thick on a 4-inch drainage fill course and should be reinforced with welded wire fabric. The 4-inch drainage mat should consist of a sand and gravel mixture, complying with Idaho Standards for Public Works Construction (ISPWC) specifications for 3/4-inch (Type 1) crushed aggregate. A moisture-retarder should be placed beneath floor slabs to minimize potential ground moisture effects on moisture-sensitive floor coverings. The granular mat should be compacted to no less than 95 percent of the maximum dry density as determined by ASTM D1557. Upon request, MTI can provide further consultation regarding installation. Control joints must be on 12-foot centers or less. CONSTRUCTION CONSIDERATIONS Recommendations in this report are based upon pavement sections of the project being founded on competent silt soils with sand soils, sandy silt soils, or compacted structural fill. Structural areas should be stripped to an elevation that exposes these soil types. Earthwork Excessively organic soils, deleterious materials, or disturbed soils generally undergo high volume changes when subjected to loads, which is detrimental to subgrade behavior in the area of pavements, floor slabs, structural fills, and foundations. Agricultural crops with associated root systems were noted at the time of our investigation. It is recommended that organic or disturbed soils, if encountered, be removed to depths of 1 foot (minimum), and wasted or stockpiled for later use. Stripping depths should be adjusted in the field to assure that the entire root zone or disturbed zone (plow depths) or topsoil are removed prior to placement and compaction of structural fill materials. Exact removal depths should be determined during grading operations by MTI personnel, and should be based upon subgrade soil type, composition, and firmness or soil stability. If underground storage tanks, underground utilities, wells, or septic systems are discovered during construction activities, they must be decommissioned then removed or abandoned in accordance with governing Federal, State, and local agencies. Excavations developed as the result of such removal must be backfilled with structural fill materials as defined in the Structural Fill section. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CopyrightTestTesting eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 11 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections MTI should oversee subgrade conditions (i.e., moisture content) as well as placement and compaction of new fill (if required) after native soils are excavated to design grade. Recommendations for structural fill presented in this report can be used to minimize volume changes and differential settlements that are detrimental to the behavior of footings, pavements, and floor slabs. Sufficient density tests should be performed to properly monitor compaction. For structural fill beneath parking and driveway areas, one in- place density test per lift for every 10,000 square feet is recommended. Dry Weather If construction is to be conducted during dry seasonal conditions, many problems associated with soft soils may be avoided. However, some rutting of subgrade soils may be induced by shallow groundwater conditions related to springtime runoff or irrigation activities during late summer through early fall. Solutions to problems associated with soft subgrade soils are outlined in the Soft Subgrade Soils section. Problems may also arise because of lack of moisture in native and fill soils at time of placement. This will require the addition of water to achieve near-optimum moisture levels. Low-cohesion soils exposed in excavations may become friable, increasing chances of sloughing or caving. Measures to control excessive dust should be considered as part of the overall health and safety management plan. Wet Weather If construction is to be conducted during wet seasonal conditions (commonly from mid-November through May), problems associated with soft soils must be considered as part of the construction plan. During this time of year, fine-grained soils such as silts and clays will become unstable with increased moisture content, and eventually deform or rut. Additionally, constant low temperatures reduce the possibility of drying soils to near optimum conditions. Soft Subgrade Soils Shallow fine-grained subgrade soils that are high in moisture content should be expected to pump and rut under construction traffic. During periods of wet weather, construction may become very difficult if not impossible. The following recommendations and options have been included for dealing with soft subgrade conditions: • Track-mounted vehicles should be used to strip the subgrade of root matter and other deleterious debris. Heavy rubber-tired equipment should be prohibited from operating directly on the native subgrade and areas in which structural fill materials have been placed. Construction traffic should be restricted to designated roadways that do not cross, or cross on a limited basis, proposed roadway or parking areas. • Soft areas can be over-excavated and replaced with granular structural fill. • Construction roadways on soft subgrade soils should consist of a minimum 2-foot thickness of large cobbles of 4 to 6 inches in diameter with sufficient sand and fines to fill voids. Construction entrances should consist of a 6-inch thickness of clean, 2-inch minimum, angular drain-rock and must be a minimum of 10 feet wide and 30 to 50 feet long. During the construction process, top dressing of the entrance may be required for maintenance. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 12 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections • Scarification and aeration of subgrade soils can be employed to reduce the moisture content of wet subgrade soils. After stripping is complete, the exposed subgrade should be ripped or disked to a depth of 11/2 feet and allowed to air dry for 2 to 4 weeks. Further disking should be performed on a weekly basis to aid the aeration process. • Alternative soil stabilization methods include use of geotextiles, lime, and cement stabilization. MTI is available to provide recommendations and guidelines at your request. Frozen Subgrade Soils Prior to placement of structural fill materials or foundation elements, frozen subgrade soils must either be allowed to thaw or be stripped to depths that expose non-frozen soils and wasted or stockpiled for later use. Stockpiled materials must be allowed to thaw and return to near-optimal conditions prior to use as structural fill. The onsite, shallow silt soils are susceptible to frost heave during freezing temperatures. For exterior flatwork and other structural elements, adequate drainage away from subgrades is critical. Compaction and use of structural fill will also help to mitigate the potential for frost heave. Complete removal of frost susceptible soils for the full frost depth, followed by replacement with a non-frost susceptible structural fill, can also be used to mitigate the potential for frost heave. MTI is available to provide further guidance/assistance upon request. Structural Fill Soils recommended for use as structural fill are those classified as GW, GP, SW, and SP in accordance with the Unified Soil Classification System (USCS) (ASTM D2487). Use of silty soils (USCS designation of GM, SM, and ML) as structural fill may be acceptable. These materials require very high moisture contents for compaction and require a long time to dry out if natural moisture contents are too high and may also be susceptible to frost heave under certain conditions. Therefore, these materials can be quite difficult to work with as moisture content, lift thickness, and compactive effort becomes difficult to control. If silty soil is used for structural fill, lift thicknesses should not exceed 6 inches (loose), and fill material moisture must be closely monitored at both the working elevation and the elevations of materials already placed. Following placement, silty soils must be protected from degradation resulting from construction traffic or subsequent construction. Recommended granular structural fill materials, those classified as GW, GP, SW, and SP, should consist of a 6-inch minus select, clean, granular soil with no more than 50 percent oversize (greater than 3/4-inch) material and no more than 12 percent fines (passing No. 200 sieve). These fill materials should be placed in layers not to exceed 12 inches in loose thickness. Prior to placement of structural fill materials, surfaces must be prepared as outlined in the Construction Considerations section. Structural fill material should be moisture- conditioned to achieve optimum moisture content prior to compaction. All fill materials must be monitored during placement and tested to confirm compaction requirements, outlined below, have been achieved. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 13 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections Each layer of structural fill must be compacted, as outlined below: • Below Structures and Rigid Pavements: A minimum of 95 percent of the maximum dry density as determined by ASTM D1557. • Below Flexible Pavements: A minimum of 92 percent of the maximum dry density as determined by ASTM D 15 57 or 95 percent of the maximum dry density as determined by ASTM D698. The ASTM D 15 57 test method must be used for samples containing up to 40 percent oversize (greater than 3/4— inch) particles. If material contains more than 40 percent but less than 50 percent oversize particles, compaction of fill must be confirmed by proof rolling each lift with a 10-ton vibratory roller (or equivalent) until the maximum density has been achieved. Density testing must be performed after each proof rolling pass until the in-place density test results indicate a drop (or no increase) in the dry density, defined as maximum density or "break over" point. The number of required passes should be used as the requirements on the remainder of fill placement. Material should contain sufficient fines to fill void spaces, and must not contain more than 50 percent oversize particles. Excavations Shallow excavations that do not exceed 4 feet in depth may be constructed with side slopes approaching vertical. Below this depth, it is recommended that slopes be constructed in accordance with Occupational Safety and Health Administration (OSHA) regulations, Section 1926, Subpart P. Based on these regulations, on-site soils are classified as type "C" soil, and as such, excavations within these soils should be constructed at a maximum slope of 1'/2 feet horizontal to 1 foot vertical (1%2:1) for excavations up to 20 feet in height. Excavations in excess of 20 feet will require additional analysis. Note that these slope angles are considered stable for short-term conditions only, and will not be stable for long-term conditions. During the subsurface exploration, test pit sidewalls generally exhibited little indication of collapse; however, sloughing of fill materials and native granular sediments from test pit sidewalls was observed, particularly after penetration of the water table. For deep excavations, native granular sediments cannot be expected to remain in position. These materials are prone to failure and may collapse, thereby undermining upper soil layers. This is especially true when excavations approach depths near the water table. Care must be taken to ensure that excavations are properly backfilled in accordance with procedures outlined in this report. Groundwater Control Groundwater was encountered during the investigation but is anticipated to be below the depth of most construction. Special precautions may be required for control of surface runoff and subsurface seepage. It is recommended that runoff be directed away from open excavations. Silty and clayey soils may become soft and pump if subjected to excessive traffic during time of surface runoff. Ponded water in construction areas should be drained through methods such as trenching, sloping, crowning grades, nightly smooth drum rolling, or installing a French drain system. Additionally, temporary or permanent driveway sections should be constructed if extended wet weather is forecasted. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 14 of 26 INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GENERAL COMMENTS When plans and specifications are complete, or if significant changes are made in the character or location of the proposed roadway, consultation with MTI should be arranged as supplementary recommendations may be required. Suitability of subgrade soils and compaction of structural fill materials must be verified by MTI personnel prior to placement of structural elements. Additionally, monitoring and testing should be performed to verify that suitable materials are used for structural fill and that proper placement and compaction techniques are utilized. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 Copy www.mti-id.com•mWaIm Testing ti-id.com Testing &2 Inspection,Inc. MATERIALS 31 August 2016 TESTI NG & Page# 15 of 26 INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections REFERENCES Ada County Highway District (ACHD) (2013). Ada County Highway District Policy Manual October 2015). [Online] Available: <http://www.achdidaho.org/AboutACHD/PolicyManual.aspx>(2016). American Society for Testing and Materials (ASTM) (2013). Standard Test Method for Materials Finer than 75-µm (No. 200) Sieve in Mineral Aggregates by Washing: ASTM C117. West Conshohocken,PA: ASTM. American Society for Testing and Materials (ASTM) (2014). Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates: ASTM C136. West Conshohocken,PA: ASTM. American Society for Testing and Materials (ASTM) (2012). Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort: ASTM D698. West Conshohocken,PA: ASTM. American Society for Testing and Materials (ASTM) (2012). Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort: ASTM D1557.West Conshohocken,PA: ASTM. American Society for Testing and Materials (ASTM) (2013). Standard Test Methods for Resistance Value (R-Value) and Expansion Pressure of Compacted Soils: ASTM D2844.West Conshohocken,PA: ASTM. American Society for Testing and Materials (ASTM) (2011). Standard Practice for Classification of Soils for Engineering Purposes(Unified Soil Classification System): ASTM D2487.West Conshohocken,PA: ASTM. American Society for Testing and Materials (ASTM) (2010). Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils: ASTM D4318.West Conshohocken,PA: ASTM. Desert Research Institute.Western Regional Climate Center. [Online] Available: <http://www.wrcc.dri.edu/>(2016). Local Highway Technical Assistance Council (LHTAC) (2010). Idaho Standards for Public Works Construction, 2010. Boise, ID: Author. Othberg, K. L. and Stanford, L. A., Idaho Geologic Society (1992). Geologic Map of the Boise Valley and Adjoining Area,Western Snake River Plain, Idaho. (scale 1:100 00). Boise,ID: Joslyn and Morris. U.S. Department of Labor, Occupational Safety and Health Administration. CFR 29, Part 1926, Subpart P: Safety and Health Regulations for Construction,Excavations(1986). [Online] Available: <www.osha.gov>(2016). U.S. Geological Survey (2016). National Water Information System: Web Interface. [Online] Available: <http://waterdata.usgs.gov/nwis>(2016). 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing 2016 Materials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 16 of 26 INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections APPENDICES ACRONYM LIST AASHTO: American Association of State Highway and Transportation Officials ACHD: Ada County Highway District ACI American Concrete Institute ASCE American Society of Civil Engineers ASTM: American Society for Testing and Materials bgs: below ground surface CBR: California Bearing Ratio D: natural dry unit weight,pcf ESAL Equivalent Single Axle Load GS: grab sample IBC: International Building Code IDEQ Idaho Department of Environmental Quality ISPWC: Idaho Standards for Public Works Construction ITD: Idaho Transportation Department LL: Liquid Limit M: water content MSL: mean sea level N: Standard"N'penetration: blows per foot, Standard Penetration Test NP: nonplastic OSHA Occupational Safety and Health Administration PCCP: Portland Cement Concrete Pavement PERM: vapor permeability PI: Plasticity Index PID: photoionization detector PVC: polyvinyl chloride QC: cone penetrometer value,unconfined compressive strength,psi Qp: Penetrometer value,unconfined compressive strength,tsf Qu: Unconfined compressive strength,tsf RMR Rock Mass Rating RQD Rock Quality Designation R-Value Resistance Value SPT: Standard Penetration Test(140:pound hammer falling 30 in. on a 2:in. split spoon) USCS: Unified Soil Classification System USDA: United States Department of Agriculture UST: underground storage tank V: vane value,ultimate shearing strength,tsf 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 17 of 26 INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GEOTECHNICAL GENERAL NOTES RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION Coarse-Grained Soils SPT Blow Counts (N) Fine-Grained Soils SPT Blow Counts(N) Very Loose: <4 Very Soft: <2 Loose: 4-10 Soft: 2-4 Medium Dense: 10-30 Medium Stiff: 4-8 Dense: 30-50 Stiff: 8-15 Very Dense: >50 Very Stiff: 15-30 Hard: >30 Moisture Content Cementation Description Field Test Description Field Test Dry Absence of moisture,dusty,dry to touch Weakly Crumbles or breaks with handling orslight finger pressure Moist Damp but not visible moisture Moderately Crumbles or beaks with considerable finger pressure Wet Visible free water,usually soil is below Strongly Will not crumble or break with finger water table g pressure PARTICLE SIZE Boulders: >12 in. Coarse-Grained Sand: 5 to 0.6 mm Silts: 0.075 to 0.005 min Cobbles: 12 to 3 in. Medium-Grained Sand: 0.6 to 0.2 min Clays: <0.005 mm Gravel: 3 in.to 5 min Fine-Grained Sand: 0.2 to 0.075 min UNIFIED SOIL CLASSIFICATION SYSTEM Major Divisions Symbol Soil Descriptionsim Gravel&Gravelly GW Well-graded gravels;gravel/sand mixtures with little or no fines Soils GP Poorly-graded gravels;gravel/sand mixtures with little or no fines Coarse-Grained <50% coarse fraction GM Silty gravels;poorly-graded gravel/sand/silt mixtures Soils passes No.4 sieve GC Clayey gravels;poorly-graded gravel/sand/clay mixtures <50% passes No.200 Sand&Sandy SW Well-graded sands;gravelly sands with little or no fines sieve Soils SP Poorly-graded sands;gravelly sands with little or no fines >50% coarse fraction SM Silty sands;poorly-graded sand/gravel/silt mixtures passes No.4 sieve SC Clayey sands;poorly-graded sand/gravel/clay mixtures ML Inorganic silts; sandy,gravelly or clayey silts Silts&Clays CL Lean clays;inorganic,gravelly,sandy,or silty,low to medium-plasticity clays Fine Grained LL<50 Soils>50% OL Organic,low-plasticity clays and silts passes No.200 MH Inorganic,elastic silts;sandy,gravelly or clayey elastic silts sieve Silts&Clays CH Fat clays;high-plasticity,inorganic clays LL>50 OH Organic,medium to high-plasticity clays and silts Highly Organic Soils PT Peat,humus,hydric soils with high organic content 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 18 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-1 Date Advanced: 19 Aug 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman's Backhoe Service Location: See Site Map Plates Latitude: 43.6639557 Longitude: -116.4682846 Depth to Water Table: Not Encountered Total Depth: 11.2 Feet bgs Depth Field Description and USCS Soil and Sediment Sample Sample Depth Lab Feet bgs) Classification Type Feet bgs) Qp Test ID Silt with Sand (ML): Dark brown, slightly moist, 0.0-1.9 stiff to very stiff, with fine-grained sand. 1.5-2.5 --Organics to a depth of 0.8 oot bgs. Silty Sand (SM): Brown, dry to slightly moist, dense to very dense, with fine to medium-grained 1.9-3.7 sand. --A thin layer of weak calcium carbonate cementation encountered at 2.7 feet bgs. Poorly Graded Gravel with Sand (GP): Light 3.7-11.2 brown, dry to slightly moist, medium dense to dense, with fine to coarse-grained sand, fine to coarse gravel, and 4-inch-minus cobbles. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 19 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-2 Date Advanced: 19 Aug 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman's Backhoe Service Location: See Site Map Plates Latitude: 43.6665344 Longitude: -116.4682312 Depth to Water Table: Not Encountered Total Depth: 15.0 Feet bgs Notes: Piezometer installed to 15.0 feet bgs. Depth Field Description and USCS Soil and Sediment Sample Sample Depth Lab Feet bgs) Classification Type Feet bgs) Qp Test ID Silt with Sand (ML): Dark brown to brown, 0.0-4.3 slightly moist, stiff to hard, with fine-grained 2.0-4.5 sand. --Organics to a depth of 0.9 oot bgs. Silty Sand (SM): Brown, dry to slightly moist, dense to very dense, with fine to medium-grained sand. 4.3-11.1 --Moderate to strong induration encountered from 4.3 to 7.1 feet bgs. --Moderate calcium carbonate cementation encountered from 7.1 to 9.1 feet bgs. Poorly Graded Gravel with Sand (GP): Light 11.1-15.0 brown, dry to slightly moist, medium dense to dense, with fine to coarse-grained sand, fine to coarse gravel, and 6-inch-minus cobbles. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 20 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-3 Date Advanced: 19 Aug 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman's Backhoe Service Location: See Site Map Plates Latitude: 43.6664276 Longitude: -116.4586716 Depth to Water Table: Not Encountered Total Depth: 8.1 Feet bgs Depth Field Description and USCS Soil and Sediment Sample Sample Depth Lab Feet bgs) Classification Type Feet bgs) Qp Test ID Silt with Sand (ML): Dark brown, dry to slightly 0.0-3.4 moist, very stiff, with fine-grained sand. 2.5-3.75 --No organics noted within the test pit. Silty Sand (SM): Brown to light brown, dry to slightly moist, dense to very dense, with fine to 3.4-6.2 medium-grained sand. --Weak to moderate calcium carbonate cementation from 3.6 to 4.1 feet bgs. Poorly Graded Gravel with Sand (GP): Light 6.2-8.1 brown, dry, medium dense to dense, with fine to coarse-grained sand,fine to coarse gravel, and 5- inch-minus cobbles. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtiCa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 21 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-4 Date Advanced: 19 Aug 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman's Backhoe Service Location: See Site Map Plates Latitude: 43.6635551 Longitude: -116.4601364 Depth to Water Table: Not Encountered Total Depth: 7.9 Feet bgs Depth Field Description and USCS Soil and Sediment Sample Sample Depth Lab Feet bgs) Classification Type Feet bgs) Qp Test ID Sandy Silt (ML): Dark brown to brown, dry to 0.0-3.7 slightly moist, stiff to very stiff, with fine-grained Bulk 0.5-1.0 1.25-3.0 `�/ sand. R-Value --Organics to a depth of 0.8 oot bgs. Silty Sand(SM): Brown, dry, dense to very dense, 3.7-6.1 with fine to medium-grained sand. --Moderate calcium carbonate cementation encountered from 5.1 to 5.4 feet bgs. Poorly Graded Gravel with Sand (GP): Light 6.1-7.9 brown, dry, medium dense to dense, with fine to coarse-grained sand,fine to coarse gravel, and 4- inch-minus cobbles. Lab Test ID M Sieve Analysis %passing) % #4 #10 #40 #100 #200 A 18.1 28 5 98 96 87 69 61.0 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtKa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 22 of 26 Orot INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-5 Date Advanced: 19 Aug 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman's Backhoe Service Location: See Site Map Plates Latitude: 43.6633445 Longitude: -116.4601364 Depth to Water Table: 15.2 Feet bgs Total Depth: 15.8 Feet bgs Notes: Piezometer installed to 15.8 feet bgs. Depth Field Description and USCS Soil and Sediment Sample Sample Depth Lab Feet bgs) Classification Type Feet bgs) Qp Test ID Silty Sand with Gravel Fill (SM-FILL): Light 0.0-2.3 brown to brown, dry, medium dense to dense, with fine to coarse-grained sand and fine to coarse ravel. Poorly Graded Gravel with Sand (GP): Light 2.3-15.8 brown, dry to saturated, medium dense to dense, with fine to coarse-grained sand, fine to coarse gravel, and 4-inch-minus cobbles. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtiCa)mti-id.com CTesti Testing eMaterials Testing&Inspection,Inc. MATERIALS 31 August2016 TESTI NG & Page# 23 of 26 INSPECTION b 161073g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GRAVEL EQUIVALENT METHOD—PAVEMENT THICKNESS DESIGN PROCEDURES Pavement Section Design Location: Pollard Lane Realignment,Rural Road Average Daily Traffic Count: 300 All Lanes&Both Directions Design Life: 20 Years Traffic Index: 6.00 Climate Factor: I R-Value of Subgrade: 12.00 Subgrade CBR Value: 5 Subgrade Mr: 7,500 R-Value of Aggregate Base: 80 R-Value of Granular Borrow: 60 Subgrade R-Value: 12 Expansion Pressure of Subgrade: 0.19 Unit Weight of Base Materials: 130 Total Design Life 18 kip ESAL's: 33,131 ASPHALTIC CONCRETE: Gravel Equivalent,Calculated: 0.384 Thickness: 0.196923077 se= 2.5 Inches Gravel Equivalent,ACTUAL: 0.41 CRUSHED AGGREGATE BASE: Gravel Equivalent(Ballast): 0.768 Thickness: 0.329 Use= 4 Inches Gravel Equivalent,ACTUAL: 0.773 SUBBASE: Gravel Equivalent(Ballast): 1.690 Thickness: 0.917 Use= 12 Inches Gravel Equivalent,ACTUAL: 1.773 TOTAL Thickness: 1.542 Thickness Required by Exp.Pressure: 0.210 Design ACHD Depth Substitution Inches Ratios Asphaltic Concrete(at least 2.5): 2.50 1.95 Asphalt Treated Base(at least 4.2): 0.00 Cement Treated Base(at least 4.2): 0.00 Crushed Aggregate Base(at least 4.2): 4.00 1.10 Subbase(at least 4.2): 12.00 1.00 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 Copyright www.mti-id.com•mti(a'- Testing&Inspection,Inc.mti-id.com Materialsnc. Inspection, CMATERIALS 31 August 2016 TESTI NG Page# 24 of 26 INSPECTION b 161073 g_geotech.docx ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections R-VALUE LABORATORY TEST DATA Source and Description: TP-4, 0.5-1.0— Sandy Silt Date Obtained: August 19, 2016 Sample ID: 16-7545 Sampling and ASTM D75: AASHTO T2: X ASTM AASHTO X Preparation: D421: T87: Test Standard: ASTM AASHTO Idaho T8: X D2844: T 190: Sample A B C Dry Density(lb/ft3) 106.3 104.1 101.7 Moisture Content (%) 17.7 19.5 20.1 Expansion Pressure (psi) 0.51 0.24 0.12 Exudation Pressure (psi) 416 247 134 R-Value 16 13 10 R-Value @ 200 psi Exudation Pressure= 12 R-Value @ Exudation Pressure 17.0 16.0 15.0 14.0 j 13.0 12.0 11.0 10.0 9.0 450 400 350 300 250 200 150 100 Exudation Pressure(psi) 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copy ww Testing w.mti-id.com•mti6d)mti-id.com Testing &2 Inspection,Inc. m A. CAN ADA RD CAN ADA RC] Id G0.N ADA 4 0 e'3 cti A C �• rt � 2 rr Ry Gn CD ILE l 0 La M pjt�-- {l1 Gi to In 'S-_AG t E W N m cno (D mo o -oo m Z p o w cQ `c CDM O' C>_ Z o z coo y 3 v C m 0 p N G N 7 0o m 0 3 v m m N m w� ornCD � � � co N m m t o � O D .. CD m m v Ln N x 6 fD M �- 3 0�N I1 Z W O ^' nl D v00i g� Z � N o m 3 II I II I I L POLLARD LANE II II II � II II O r II II o II I o r II z I II I LEVI LANE CD ®cLi � I D . N O O m� �mW I W N N j c,D m o orb 4 R� --a o 0 m z O o, y n r0 r� v a o -i < °' �' o 0 0 0 o m m w (a 6 O O CD 0 X 0 X la) X z fn Im �_ m o O• aa) O• aa) aa) 0 r rn o CO v CD m � � CD w � Q s m o rn r m O' p Z m � la) = o UCD T1 'A D � © za CD C cn ^'m 3 V —1 -q v n vx � mom ID Q @Nnz � � -- aN ON N ® m z C g � PCD N m N MATERIALS 4 March 2019 TESTING & Page# 1 of 6 INSPECTION b 1 61073g_addendum#1-revised.docx AN An AS COMPANY ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections Mr. Kameron Nauahi Brighton Corporation 12601 West Explore Drive, Suite 200 Boise, ID 83713 208-378-4000 Re: Addendum#1 —Pavement Recommendations Pollard Lane Realignment Pollard Lane & Chinden Boulevard Meridian, ID Dear Mr. Wardle: This addendum report presents recommendations not requested at the time of the previously issued MTI Geotechnical Engineering Report (13161073g). Descriptions of general site characteristics and the proposed project are available in the previous report. Unless otherwise noted in this addendum, all initial recommendations, limitations, and warranties expressed in the previous report must be adhered to. Recommended Pavement Sections As required by Ada County Highway District (ACHD), MTI has used a traffic index of 6 for local streets and 8 for collector and commercial streets to determine the necessary pavement cross-section for the site. MTI has made assumptions for traffic loading variables based on the character of the proposed construction. The Client should review these assumptions to make sure they reflect intended use and loading of pavements both now and in the future. MTI collected a sample of near-surface soils for Resistance Value (R-value) testing representative of soils to depths of 2 feet below existing ground surface. This sample, consisting of sandy silt collected from test pit 4, yielded a R-value of 12. The following are minimum thickness requirements for assured pavement function. Depending on site conditions, additional work, e.g. soil preparation, may be required to support construction equipment. These have been listed within the Soft Subgrade Soils section of the original report. Results of the test are graphically depicted in the Enclosures section. Flexible Pavement Sections The Gravel Equivalent Method, as defined in Section 500 of the State of Idaho Department of Transportation (ITD) Materials Manual, was used to develop the pavement sections. ACHD parameters for traffic index and substitution ratios, which were obtained from the ACHD Policy Manual, were also used in the design. Calculation sheets provided in the Enclosures section indicate the soils constant, traffic loading, traffic projections, and material constants used to calculate the pavement sections. MTI recommends that materials used in the construction of asphaltic concrete pavements meet the requirements of the ISPWC Standard Specification for Highway Construction. Construction of the pavement section should be in accordance with these specifications and should adhere to guidelines recommended in the Construction Considerations section of the original report. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtiCa)mti-id.com Copynght©g&Inspection — Testing MATERIALS 4 March 2019 TESTING & Page#2 of 6 INSPECTION b 1 61073g_addendum#1-revised.docx AN An AS COMPANY ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections Gravel Equivalent Method Flexible Pavement Specifications Pavement Section Local Roadway Section Collectors and Commercial Component' Roadway Sections Asphaltic Concrete 2.5 Inches 3.25 Inches Crushed Aggregate Base 4.0 Inches 4.0 Inches Structural Subbase 12.0 Inches 17.0 Inches Not Required for Native Soils Not Required for Native Soils Compacted Subgrade 12.0 Inches to 95% of ASTM 12.0 Inches to 95%of ASTM D698 for Existing Fill D698 for Existing Fill Materials/Plow Zones Materials/Plow Zones 1It will be required for MTI personnel to verify subgrade competency at the time of construction. Asphaltic Concrete: Asphalt mix design shall meet the requirements of ISPWC, Section 810 Class III plant mix. Materials shall be placed in accordance with ISPWC Standard Specifications for Highway Construction. Aggregate Base: Material complying with ISPWC Standards for Crushed Aggregate Materials. Structural Subbase: Material complying with requirements for granular structural fill (uncrushed) as defined in ISPWC. Common Pavement Section Construction Issues The subgrade upon which above pavement sections are to be constructed must be properly stripped, compacted (if indicated), inspected, and proof-rolled. Proof rolling of subgrade soils should be accomplished using a heavy rubber-tired, fully loaded, tandem-axle dump truck or equivalent. Verification of subgrade competence by MTI personnel at the time of construction is required. Fill materials on the site must demonstrate the indicated compaction prior to placing material in support of the pavement section. MTI anticipated that pavement areas will be subjected to moderate traffic. MTI does not anticipate pumping material to become evident during compaction, but subgrade clays and silts near and above optimum moisture contents may tend to pump. Pumping or soft areas must be removed and replaced with structural fill. Fill material and aggregates in support of the pavement section must be compacted to no less than 95 percent of the maximum dry density as determined by ASTM D698 for flexible pavements and by ASTM D1557 for rigid pavements. If a material placed as a pavement section component cannot be tested by usual compaction testing methods, then compaction of that material must be approved by observed proof rolling. Minor deflections from proof rolling for flexible pavements are allowable. Deflections from proof rolling of rigid pavement support courses should not be visually detectable. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtiCa)mti-id.com Copynght©g&Inspection — Testing 4 March 2019 MATERIALS TESTING & Page # 3 of 6 INSPECTION b161073g_addeadum41-revised.doex AN ATLAS COMPANY ❑ Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections MT1 appreciates this opportunity to be of service to you and looks forward to working with you in the future. If you have questions, please call (208) 376-4748. Respectfully Submitted, Materials Testing& Inspection NAL �C�i55`.O ENS y o ° � Jacob Schlador, P.E. 18309 Reviewed by: Monica Saculles, P.E. Geotechnical En irlee 3 -y -I Senior Geotechnical Engineer g g v'gCgPF OF Enclosures: �B SCHVP Gravel Equivalent Method Pavement Thickness Design Procedures R-Value Laboratory Test Data 2791 S Victory View Way• Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtiRmti-id. — t g&=napeeu on MATERIALS 4 March 2019 TESTING & Page#4 of 6 INSPECTION b 1 61073g_addendum#1-revised.docx AN An AS COMPANY ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GRAVEL EQUIVALENT METHOD—PAVEMENT THICKNESS DESIGN PROCEDURES Pavement Section Design Location: Pollard Subdivision,Local Roadways Average Daily Traffic Count: 300 All Lanes&Both Directions Design Life: 20 Years Traffic Index: 6.00 Climate Factor: 1 R-Value ofSubgrade: 12.00 Subgrade CBR Value: 5 Subgrade Mr: 7,500 R-Value of Aggregate Base: 80 R-Value of Granular Borrow. 60 Subgrade R-Value: 12 Expansion Pressure of Subgrade: 0.19 Unit Weight of Base Materials: 130 Total Design Life 18 kipESAL's: 33,131 ASPHALTIC CONCRETE: Gravel Equivalent,Calculated: 0.384 Thickness: 0.196923077 Use= 2.5 Inches Gravel Equivalent,ACTUAL: 0.41 CRUSHED AGGREGATE BASE: Gravel Equivalent(Ballast): 0.768 Thickness: 0.329 Use= 4 hiches Gravel Equivalent,ACTUAL: 0.773 SUBBASE: Gravel Equivalent(Ballast): 1.690 Thickness: 0.917 Use= 12 hiches Gravel Equivalent,ACTUAL: 1.773 TOTAL Thickness: 1.542 Thickness RequiredbyExp.Pressure: 0.210 Design ACHD Depth Substitution Inches Ratios Asphaltic Concrete(at least 2.5): 2.50 1.95 Asphalt Treated Base(at least 4.2): 0.00 Cement Treated Base(at least 4.2): 0.00 Crushed Aggregate Base(at least 4.2): 4.00 1.10 Subbase(atleast 4.2): 12.00 1.00 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 Copyn www.mti-id.com•mtiCa) Testing mtkid.com ght©g&Inspection MATERIALS 4 March 2019 TESTING & Page# 5 of 6 INSPECTION b 1 61073g_addendum#1-revised.docx AN An AS COMPANY ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections GRAVEL EQUIVALENT METHOD—PAVEMENT THICKNESS DESIGN PROCEDURES Pavement Section Design Location: Pollard Subdivision,Commercial and Collector Streets Average Daily Traffic Count: 700 All Lanes&Both Directions Design Life: 20 Years Traffic Index: 8.00 Climate Factor: 1 R-Value of Subgrade: 12.00 Subgrade CBR Value: 5 Subgrade Mr: 7,500 R-Value of Aggregate Base: 80 R-Value of Granular Borrow: 60 Subgrade R-Value: 12 Expansion Pressure of Subgrade: 0.19 Unit Weight of Base Materials: 130 Total Design Life 18 kip ESAL's: 371,659 ASPHALTIC CONCRETE: Gravel Equivalent,Calculated: 0.512 Thickness: 0.262564103 Use= 3.25 Inches Gravel Equivalent,ACTUAL: 0.53 CRUSHED AGGREGATE BASE: Gravel Equivalent(Ballast): 1.024 Thickness: 0.451 Ell Use= 4 Inches Gravel Equivalent,ACTUAL: 0.895 SUBBASE: Gravel Equivalent(Ballast): 2.253 Thickness: 1.358 Use= 17 Inches Gravel Equivalent,ACTUAL: 2.311 TOTAL Thickness: 2.021 Thickness Required by Exp.Pressure: 0.210 Design ACHD Depth Substitution Inches Ratios Asphaltic Concrete(at least 2.5): 3.25 1.95 Asphalt Treated Base(at least 4.2): 0.00 Cement Treated Base(at least 4.2): 0.00 Crushed Aggregate Base(at least 4.2): 4.00 1.10 Subbase(at least 4.2): 17.00 1.00 2791 S Victory View Way•Boise, ID 83709•(208)376-4748•Fax(208)322-6515 www.mti-id.com•mtiCa) Testing mtkid.com Copynght©g& Materials & - Inspection MATERIALS 4 March 2019 TESTING & Page# 6 of 6 INSPECTION b 161073 g_addendum#1-revised.docx AN An AS COMPANY ❑Environmental Services ❑Geotechnical Engineering ❑Construction Materials Testing ❑Special Inspections R-VALUE LABORATORY TEST DATA Source and Description: TP-4, 0.5-1.0— Sandy Silt Date Obtained: August 19, 2016 Sample ID: 16-7545 Sampling and ASTM D75: AASHTO T2: X ASTM AASHTO X Preparation: D421: T87: Test Standard: ASTM AASHTO Idaho T8: X D2844: T190: Sample A B C Dry Density(lb/ft) 106.3 104.1 101.7 Moisture Content(%) 17.7 19.5 20.1 Expansion Pressure (psi) 0.51 0.24 0.12 Exudation Pressure (psi) 416 247 134 R-Value 16 13 10 R-Value @ 200 psi Exudation Pressure= 12 R-Value @ Exudation Pressure 17.0 16.0 15.0 3 14.0 j 13.0 12.0 11.0 10.0 9.0 450 400 350 300 250 200 150 100 Exudation Pressure(psi) 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyn ww Testing w.mti-id.com•mtiCa)mti-id.com ght©g&Inspection GROUND WATER MONITORING MID-YEAR REPORT - POLLARD LANE PROJECT (NRS, 11/11/2023) NATURAL RESOURCE SLR/ LLC MIKE RAYMOND Consulting, Soil Evaluations & Data Collection _ Phone: 208.409-1505 Email:mraydirty@gmail.com November 11, 2023 Daniel Frisby Brighton Corporation 2929 Navigation Dr., Suite 400 Meridian, ID 83642 Re: Ground water monitoring mid-year report—Pollard Lane project I have completed monthly monitoring of ground water levels for the Pollard Lane project for the 2023 season. Attached you will find worksheets and graphics showing the data recorded to date as well as a map showing piezometer locations on the site for reference. All three piezometers have remained dry throughout the monitoring period. These dry piezometers have bottom elevations ranging from 2513.1 to 2528.0 feet. Bottom depths range from 138 to 177 inches (11.5 to 14.8 feet)below ground surface (bgs). There has been no active irrigation of fields on the property this year. Precipitation for the calendar year through September was 123 percent of normal for the area, with March and August being particularly wet months. If there are any questions,please give me a call or reach me by e-mail. Thank you. transmitted via e-mail MICHAEL A. RAYMOND, M.S. Soil Scientist 5740 N. 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