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Home My WebLink AboutCC - Storm Drainage Calcs Prepared For: Sessions Parkway Subdivision TGI Corp. & City of Meridian Meridian, Idaho Storm Drainage Report F.Soti AL tw6,, Q�o� ��srERFo yFF Digitally signed by 1 4 Matthew S. Derr, PE Date: 2023.03.17 �qTTof 13:31 :10 -06'00' yE W S o Prepared By: Matthew S. Derr, P.E. Project Engineer KM Engineering, LLP 5725 N. Discovery Way Boise, ID 83713 208.639.6939 mderr@kmengllp.com 1CM March 2023 Project No: 23-021 E N G I N E E R I N G TABLE OF CONTENTS Introduction ................................................................................................................................. 1 ProjectDescription ...................................................................................................................... 1 SiteDescription............................................................................................................................... 1 Scopeand Methods ...................................................................................................................... 1 ExistingDrainage Conditions .......................................................................................................... 1 Proposed Drainage Conditions and Analysis .................................................................................. 1 DrainageSwales.............................................................................................................................. 2 Summary......................................................................................................................................... 3 APPENDICES Appendix A - Figures Figure 1 -Vicinity Map Figure 2 - Pre-Development Drainage Map Figure 2 - Post-Development Drainage Map Appendix B - Tables Table 1 - Peak Flow Rate Summary Appendix C - Calculations Post-Development 25-year Calculations Post-Development 100-year Calculations Drainage Swale Calculations Appendix D - Geotechnical Engineering Report Geotechnical Engineering Evaluation, Village Apartments (STRATA, 15 December 2015) INTRODUCTION The purpose of this report is to show that the storm drainage facilities for the proposed Sessions Parkway Subdivision are designed to meet the City of Meridian Stormwater Management Manual requirements and the water quality requirements of the Idaho Department of Environmental Quality (DEQ). This report has been prepared at the request of the developer, TGI Corp. PROJECT DESCRIPTION The Project consists of undeveloped commercial land to be subdivided into five (5) commercial lots. The proposed improvements to the site include roadways, sidewalks, lot grading, and site utilities. SITE DESCRIPTION The Project site is located at 2700 N. Eagle Road, Meridian, Idaho. See Appendix A, Figure 1 for a vicinity map of the project. The proposed Project area is 5.32± acres. SCOPE AND METHODS The Rational Method is the standard method for small catchments and was used to calculate pre-development and post-development peak runoff rates and runoff volumes. The Rational Method provided in the attached 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 Rate Summary, for a summary of flow rates. Calculations for drainage swales was completed to verify capacity. EXISTING DRAINAGE CONDITIONS The pre-project watershed consists of demolished buildings and agricultural land and was irrigated through flood irrigation. The flow path for the existing drainage basin involves overland sheet flow from south to north with irrigation wastewater being collected through a field drain at the northeast corner of the Project site. There are no existing storm drainage facilities in place to reduce the peak runoff volumes. PROPOSED DRAINAGE CONDITIONS AND ANALYSIS The proposed drainage system improvements consist of roadway borrow ditches with sand windows. The post-development site was broken into five (5) basins as shown in Appendix A, Figure 2 - Post-Development Drainage Map. A composite C value was used for all basins per Table 2 of the Stormwater Management Manual. Each basin was delineated according to the tributary area draining to each drainage facility. For individual sub-basin peak flow calculations, in addition to combined sub-basin peak flows used for downstream facility sizing and analysis, see Table 1 (Peak Flow Rate Summary). Storm water runoff consists of overland sheet flow over short grasses, and is then conveyed with a drainage swale for treatment and infiltration. 1 SUMMARY This report determines that the Project storm water design sizing and analysis conforms to the City of Meridian storm water design criteria. 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P SHEET LEGEND I10 I Xx X AREA/CR I RESM EXISTING FLOW DIRECTION f / t g l i 1 1 _ _ — --- r 2624 �sz� zszs —2szs.� d �•e so re—n — - _ ie'so — — ie'c 71 ir ————————— -- —__ —s-------I RE w •�.• 9 I 27�� /�j / /�� \ , \\ I \ air assLT ayu as,��_ I I Ir��2� 2/i// ��/�� I / < > ) 2630�I^\\ I �1 I,I�I \—�2623 ` Z 2623� ICI -l I I�4y ``�Jl Il f(Io�111 II�IIIIIIII / IIIIIIIIIII��I` ®® h BUILDING D I \`� l �iiil 1 / I / 1� IIII II Ill �I IIII IIIIIIIII��I Yt/I _ J III , ( llllll�`6\,� / 111Ulllllll�z6A5 III v \ ��/ / IIII III/1 I I I I I y �26ZS� I�IIII II III Z 111 I III Iql Irk - i_ � I� IIIIIIIIIIIIIIIII�'�QS�IIIIIIIIIIIIIIIII�III I I IIIIIII�.� o I„ >_ z I as w w o 4-- I BUILDING d G Lu > ��11('� I I z 0 / \ Lu Lu E.LESLIE DR. \ I I wK / �—� �\ \ ✓ N IY Lu Co n 19 I � I g I I \ 3 I 'rn\ �— ENGINEERING 6725 NORTH DISCOVERY WAY \O— BOISE,IDAH083713 PHONE(208)639-6939 9 ` kmengllp.com \ I T DESIGN BY: KWK DRAWN BY: KWK CHECKED BY: MSD A DATE: 3/I6/23 _ PRE DEVELOPMENT DRAINAGE PROJECR: 23-021 o aD 80 120 SHEET NO. s Plan Scale:1"=40' 1 OF 1 SHEET LEGEND % 0 DESIGN POINT I TRIBUTARY AREA/ACRES IIDESIGNED FLOW DIRECTION I ' �K �❑ I/ — y 9 I / Faso D` ,e 5o o ,e'so ,esol —t85D18'SD185D� I I e5 mom�o LD w `•.•` I I I 'I N / \� /I �I��Illf/ ' I/��///�/� IIIIIIIIII` it j i� \ `\�\ _��---------- I w _ rllll� \r \� I I 1 I I .. �\ I\��)l Il4((j1IIl //Il�lllllllll /IIIIIIIIIIIIII 1` ®® /I^ BUILDING f as os I I DW I I I I I ,y l i B �"— � Illl` ^<�� / 1111111j1111� � III IIII l� �• I Yt \ � II" �� / I N IIII✓ Jj// / Illllf I((/lI llllllllllli(IIII 1 l� Yl �� - �2.74 IIII I II 111 I III IIII Ili , ',��° I/ \ p� II IIIIII IIII IIII IIII II\\ ti, I I (e -!, la I ) IIIIIIIIII✓ IIIIII� \4. eaoea z Lu ,`JJJ ` ryJI I �5. I \Eg Q j I 0 oIf a I ,Do m oc g 0 k, ThI >- z z Lu � o 2 IV LL ALi BUILDING \\ \� d j LL° _- ------ LD Lu sD —� 11 , OA6 1 Co \I I al E — \ — — / E N G I N E E R I N G ,�) I /� 5725 NORTH DISCOVERY WAY /I —� 4 D\ BOISE,IDAHO 83713 I I In °• --� _ —\ — — — PHONE 12g8Po639m6939 kmen II -II_ .., -� DESIGN BY: KWK DRAWN BY: KINK CHECKED BY: MSD A DATE: 3/I6/23 _ POST DEVELOPMENT DRAINAGE PROJECT: 23-021 o ao ao o SHEET NO. s Plan Scale:1"=40• 1 OF 1 APPENDIX B - TABLES Figure 3 - Storm Drainage System Summary (ACHD IDF) Table 1 - Pre & Post-Development Peak Flow Rate Summary Basin Properties Peak Flow Rate C A Tc i25 i100 Q25 Q100 Acres min. in/hr in/hr cfs cfs Basin A 0.82 0.60 12.3 1.85 2.58 0.90 1.26 Basin B 0.33 2.57 10.0 1.85 2.58 1.56 2.18 Basin C 0.34 2.74 10.0 1.85 2.58 1.71 2.38 Basin D 0.23 0.06 10.0 1.85 2.58 0.03 0.04 Basin E 0.23 0.05 10.0 1.85 2.58 0.02 0.03 Design Point 1 0.82 0.60 12.3 1.85 2.58 0.90 1.26 Design Point 2 0.33 2.57 10.0 1.85 2.58 1.56 2.18 Design Point 3 0.34 2.74 10.0 1.85 2.58 1.71 2.38 KM Engineering,v2.0 Page 1 of 1 23-021 Storm Drainage System Summary APPENDIX C - CALCULATIONS POST-DEVELOPMENT 25/100-YEAR CALCULATIONS BASIN CALCULATIONS Sub-Areas Impervious Pervious Undefined Undefined Undefined Undefined Undefined ID# Name C A CA eq. Tc Cl Ai Cp Ap Cu Au Cu Au Cu Au Cu Au Cu Au Composite Acres min SF SF SF SF SF SF SF A Basin A 0.82 0.60 0.49 12.30 0.95 21,170 0.23 4,774 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 B Basin B 0.33 2.57 0.85 4.50 0.95 15,389 0.23 96,527 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 C Basin C 0.34 2.74 0.92 3.51 0.95 17,770 0.23 101,385 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 D Basin D 0.23 0.06 0.01 0.33 0.95 0 0.23 2,590 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 E Basin E 0.23 0.05 0.01 0.17 0.95 0 0.23 2,120 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 F Basin F 0.00 0.001 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 G Basin G 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 H Basin H 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 1 Basin 1 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 1 Basin J 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 K Basin K 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 L Basin L 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 M Basin M 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 N Basin N 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 O Basin O 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 P Basin P 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 Q Basin Q 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 R Basin R 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 S Basin S 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 T Basin T 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 U Basin U 0.00 0.00 0.00 0.00 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 V Basin V 0.00 0.00 0.00 0.001 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 W Basin W 0.00 0.00 0.00 0.001 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 X Basin X 0.00 0.00 0.00 0.001 0.95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 Y Basin Y 0.00 0.00 0.00 0.00E95 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0 0.55 0 Z Basin Z 0.00 0.00 0.00 0.00 0.23 0 0.1 0 0.25 0 0.35 0 0.45jJ0 EX-A Basin EX-A 0.00 0.00 0.00 0.000 0.23 0.1 0 0.25 0 0.35 0 0.45EX-B Basin EX-B 0.00 0.00 0.00 0.000 0.23 0 0.1 0 0.25 0 035 0 0.49EX-CBasin EX-C 0.00 0.00 0.00 0.000 0.23 00.10 0.250 0.350 0.49EX-D Basin EX-D 0.00 0.00 0.00 0.00 0 0.23 0 0.1 0 0.25 0 0.35 0 0.45 0.55 0 KM Engineering,v2.0 Page 143 23-021 Storm Drainage System Summary TIME OF CONCENTRATION CALCULATIONS Time of Concentration Calcluations Basin Info Overland Sheet Flow Shallow Concentrated Flow Pipe Flow Additional Tt ID7Tc slope length Mannings velocity Tt slope Intercept length velocity Tt pipe dia slope length Mannings Hydraulic velocity Tt Tt Tt Tt Tt min ft/ft ft fps min ft/ft coeff. fps min in ft/ft ft Radius fps min min min min min A 12.30 0.03 55 0.24 0.07 12.28 0.25 0.305 5 5.001 0.02 0 0.00 0.00 B 4.50 0.00 0.00 0.01 0.305 270 1.00 4.50 0 0.00 0.00 C 3.51 0.00 0.00 0.01 0.305 211 1.00 3.51 0 0.00 0.00 D 0.33 0.00 0.00 0.01 0.305 20 1.00 0.33 0 0.00 0.00 E 0.171 0.00 0.00 0.01 0.305 10 1.00 0.17 0 0.00 0.00 F 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 G 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 H 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 1 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 1 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 K 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 L 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 M 0.00 0.00 0.00 0.00 0.00 0 0.0010.00n N 0.00 0.00 0.00 0.00 0.00 0 0.00 O 0.00 0.00 0.00 0.00 0.00 0 0.00 P 0.00 0.00 0.00 0.00 0.00 0 0.00 Q 0.00 0.00 0.00 0.00 0.00 0 0.00 R 0.00 0.00 0.00 0.00 0.00 0 0.00 S 0.00 0.00 0.00 0.00 0.00 0 0.00 T 0.00 0.00 0.00 0.00 0.00 0 0.00 U 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 V 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 W 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 KU-A 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0.00 0.00 KM Engineering,-0 Page 2 of 3 23 021 St,rm Drainage System Summary DESIGN POINT CALCULATIONS ID# Name C A CA eq. Tc Contributing Basin/Design Points CA eq. CA eq. CA eq. Composite Acres min ID# Tt ID# Tt ID# Tt ID# Tt ID# Tt ID# Tt ID# Tt Adjusted Intercepte Bypass 1 Design Point 1 0.82 0.60 0.49 12.30 A 2 Design Point 2 0.33 2.57 0.85 4.50 B 3 Design Point 3 0.34 2.74 0.92 3.51 C 4 Design Point 4 0.00 0.00 0.00 0.00 5 Design Point 5 0.00 0.00 0.00 0.00 6 Design Point 6 0.00 0.00 0.00 0.00 7 Design Point 7 0.00 0.00 0.00 0.00 8 Design Point 8 0.00 0.00 0.00 0.00 9 Design Point 9 0.00 0.00 0.00 0.00 10 Design Point 10 0.00 0.00 0.00 0.00 11 Design Point 11 0.00 0.00 0.00 0.00 12 Design Point 12 0.00 0.00 0.00 0.00 13 Design Point 13 0.00 0.00 0.00 0.00 14 Design Point 14 0.00 0.00 0.00 0.00 15 Design Point 15 0.00 0.00 0.00 0.00 16 Design Point 16 0.00 0.00 0.00 0.00 17 Design Point 17 0.00 0.00 0.00 0.00 18 Design Point 18 0.00 0.00 0.00 0.00 19 Design Point 19 0.00 0.00 0.00 0.00 20 Design Point 20 0.00 0.00 0.00 0.00 21 Design Point 21 0.00 0.00 0.00 0.00 22 Design Point 22 0.00 0.00 0.00 0.00 23 Design Point 23 0.00 0.00 0.00 0.00 24 Design Point 24 0.00 0.00 0.00 0.00 25 Design Point 25 0.00 0.00 0.00 0.00 26 Design Point 26 0.00 0.00 0.00 0.00 27 Design Point 27 0.00 0.00 0.00 0.00 28 Design Point 28 0.00 0.00 0.00 0.00 29 Design Point 29 0.00 0.00 0.00 0.00 30 Design Point 30 0.00 0.00 0.00 0.00 KM Engineering,v2.0 Pa 3of3 23021 St Onn Drainage System Summary DRAINAGE SWALE CALCULATIONS ACHD Calculation Sheet for Sizing Conveyance Swale 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 Steps for Sizing Conveyance Swale User input in yellow cells. 1 Project Name 23-021 Sessions Parkway Subdivision, DP 1 2 Enter Design Inflow Q;" 1.26 cfs 3 Enter Design Outflow Qout 0.01 cfs 4 Storage Volume Vstore 4,504 ft3 VStore=(Qin-Qout)x3600 5 Set Swale Bottom Width b 1.00 ft 6 Set Swale Depth y 0.50 ft 7 Swale Side Slopes HA HA 4.00 8 Calculate cross-sectional area Axs 2.50 ft2 9 Find length for capacity L 1,801 339 ft 10 Time to Drain 12.0 hours 90%volume in 48-hours minimum OK For Conveyance Swales Only 11 Enter longitudinal slope SL ft/ft 12 Enter Manning's n for swale n 13 Solve for depth of flow YFiow 0.00 ft 14 Solve for area flow Af,ow 0.00 ft� 15 Find Wetted Perimeter P 1.00 ft P= b+2y(1+z2)1/2 16 Find Hydraulic Radius R, 0.00 ft RH =(by+zy2)/[b+2y(1+z2)1/2] 17 Find Velocity V #DIV/0! ft/s V=Q/A Is V<0.9 fps? #DIV/01 18 Calculate Length #DIV/0! ft L=Vx540s(9 minx60 s/min) Residence time 9 min minimum P:\23-021\Documents\Reports\Storm Drainage\Calculations\ACHD_SD_CALCS_112018 3/15/2023, 3:59 PM Version 10.5, November 2018 ACHD Calculation Sheet for Sizing Conveyance Swale 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 Steps for Sizing Conveyance Swale User input in yellow cells. 1 Project Name 23-021 Sessions Parkway Subdivision, DP 2 2 Enter Design Inflow Q;,, 2.18 cfs 3 Enter Design Outflow Qout 0.01 cfs 4 Storage Volume Vstore 7,816 ft3 VStore=(Qin-Qout)x3600 5 Set Swale Bottom Width b 1.00 ft 6 Set Swale Depth y 0.50 ft 7 Swale Side Slopes HA HA 4.00 8 Calculate cross-sectional area Axs 2.50 ft2 9 Find length for capacity L 3,126 600 ft 10 Time to Drain 11.7 hours 90%volume in 48-hours minimum OK For Conveyance Swales Only 11 Enter longitudinal slope SL ft/ft 12 Enter Manning's n for swale n 13 Solve for depth of flow YFiow 0.00 ft 14 Solve for area flow Af,ow 0.00 ft� 15 Find Wetted Perimeter P 1.00 ft P= b+2y(1+z2)1/2 16 Find Hydraulic Radius R, 0.00 ft RH =(by+zy2)/[b+2y(1+z2)1/2] 17 Find Velocity V #DIV/0! ft/s V=Q/A Is V<0.9 fps? #DIV/01 18 Calculate Length #DIV/0! ft L=Vx540s(9 minx60 s/min) Residence time 9 min minimum P:\23-021\Documents\Reports\Storm Drainage\Calculations\ACHD_SD_CALCS_112018 3/15/2023, 4:00 PM Version 10.5, November 2018 ACHD Calculation Sheet for Sizing Conveyance Swale 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 Steps for Sizing Conveyance Swale User input in yellow cells. 1 Project Name 23-021 Sessions Parkway Subdivision, DP 3 2 Enter Design Inflow Q;" 2.38 cfs 3 Enter Design Outflow Qout 0.01 cfs 4 Storage Volume Vstore 8,536 ft3 VStore=(Qin-Qout)x3600 5 Set Swale Bottom Width b 1.00 ft 6 Set Swale Depth y 0.50 ft 7 Swale Side Slopes HA HA 4.00 8 Calculate cross-sectional area Axs 2.50 ft2 9 Find length for capacity L 3,414 760 ft 10 Time to Drain 10.1 hours 90%volume in 48-hours minimum OK For Conveyance Swales Only 11 Enter longitudinal slope SL ft/ft 12 Enter Manning's n for swale n 13 Solve for depth of flow YFiow 0.00 ft 14 Solve for area flow Af,ow 0.00 ft� 15 Find Wetted Perimeter P 1.00 ft P= b+2y(1+z2)1/2 16 Find Hydraulic Radius R, 0.00 ft RH =(by+zy2)/[b+2y(1+z2)1/2] 17 Find Velocity V #DIV/0! ft/s V=Q/A Is V<0.9 fps? #DIV/01 18 Calculate Length #DIV/0! ft L=Vx540s(9 minx60 s/min) Residence time 9 min minimum P:\23-021\Documents\Reports\Storm Drainage\Calculations\ACHD_SD_CALCS_112018 3/15/2023, 4:00 PM Version 10.5, November 2018 APPENDIX D - GEOTECHNICAL ENGINEERING REPORT GEOTECHNICAL ENGINEERING EVALUATION, VILLAGE APARTMENTS (STRATA, 12/15/15) STFRaTa A PROFESSIONAL SERVICES CORPORATION December 15, 2015 �rtl��icy From 4-s--<*rrot4Kd uP File: B015308A Mr. Jim D. Conger Conger Management Group 4824 West Fairview Avenue Boise, Idaho 83706 jconger@congergroup.com RE: Geotechnical Engineering Evaluation Village Apartments 2600 North Eagle Road Meridian, Idaho Dear Jim: STRATA, A Professional Services Corporation (STRATA) is pleased to present our authorized Geotechnical Engineering Evaluation for the proposed Village Apartments to be located at 2600 North Eagle Road in Meridian, Idaho. Our evaluation's purpose was to explore the subsurface conditions in the proposed development area and provide geotechnical recommendations to assist project planning, design and construction. The attached report summarizes our field and laboratory test results and presents our geotechnical engineering opinions and recommendations. The following report provides specific geotechnical recommendations for preparing the site, including earthwork activities, foundation considerations and pavement section design. The project design, owner, and construction team must read, understand and implement this report in its entirety. Portions of the report cannot be relied upon individually without the supporting text of remaining sections, appendices and plates. Our opinion is the success of the proposed construction will depend on following the report recommendations, good construction practices, and providing the necessary construction monitoring, testing and consultation to verify that work has been constructed as recommended. We recommend STRATA be retained to provide monitoring, testing, and consultation services to verify our report recommendations. We appreciate the opportunity to work with Conger Management Group. We look forward to our continued involvement on this project throughout construction. Please do not hesitate to contact us if you have any questions or comments. Sincerely, STRATA �*olt1NAL 19T�,�r�'�, �o Nihan Darnall 10830 taff E g' ee Z—q5 -t5 Of;q��,� Michael G. Woodworth Engineering Manager MGW/js 8653 West Hackamore Drive,Boise,Idaho 83709 Phone.208.376.8200 Fax.208.376.8201 www.stratageotech.com Geotechnical Engineering Evaluation Village Apartments 2600 North Eagle Road Meridian, Idaho Prepared For: Mr. Jim D. Conger Conger Management Group 4824 West Fairview Avenue Boise, Idaho 83706 Prepared By: Nihan Darnall Reviewed By: Michael G. Woodworth, P.E. STRATA, Inc. 8653 W. Hackamore Dr. Boise, Idaho 83709 P. 208.376.8200 F. 208.376.8201 December 15, 2015 TABLE OF CONTENTS INTRODUCTION .............................................................................................................. 1 PROJECT UNDERSTANDING......................................................................................... 1 SUBSURFACE EVALUATION PROCEDURES ............................................................... 2 SUBSURFACE CONDITIONS.......................................................................................... 3 LABORATORY TESTING................................................................................................. 3 GEOTECHNICAL OPINIONS AND RECOMMENDATIONS............................................ 3 Earthwork....................................................................................................................... 4 Excavation Characteristics......................................................................................... 4 EstablishingSubgrades.............................................................................................. 5 StructuralFill .............................................................................................................. 6 RequiredCompaction................................................................................................. 7 Wet Weather/Wet Soil Construction........................................................................... 7 Utility Trench Construction ......................................................................................... 8 Geotextiles ................................................................................................................. 8 FoundationDesign......................................................................................................... 9 General.......................................................................................................................... 9 BearingSoil.............................................................................................................. 10 DesignCriteria.......................................................................................................... 10 Seismic Design Criteria ............................................................................................... 10 ConcreteSlabs-On-Grade........................................................................................... 11 AggregateSupport Section ...................................................................................... 11 Exterior Slab Considerations.................................................................................... 11 VaporRetarder Use ................................................................................................. 12 Pavement Subgrade Preparation and Section Design ................................................ 13 General..................................................................................................................... 13 Trafficand Subgrade................................................................................................ 14 Asphalt, Aggregate Base Course and Subbase Materials....................................... 15 Pavement Section Thickness................................................................................... 15 Pavement Maintenance Considerations................................................................... 15 SiteDrainage............................................................................................................... 16 StormwaterDisposal ................................................................................................ 16 ExteriorGrading ....................................................................................................... 17 ADDITIONAL RECOMMENDED SERVICES ................................................................. 17 Geotechnical Design Continuity................................................................................... 17 Plan and Specification Review .................................................................................... 17 Geotechnical Observation During Construction........................................................... 17 EVALUATION LIMITATIONS.......................................................................................... 18 REPORT TABLES AND FIGURES Table 1: Structural Fill Specifications and Allowable Use... .......................................6 Table 2: Required Compaction for Designated Project Areas ....................................7 Table 3: Geotextile Specifications...... ... ............... ... ............................................. 9 Table 4: Seismic Response Criteria (2012 IBC/ASCE 7)1 .......................................11 Table 5: Pavement Design Parameters ... ... .................. .......................................14 Table 6: Traffic Loading Assumptions ..................................................................14 Table 7: Standard Asphalt Pavement Section Thickness ........................................15 Figure 1: Flow Chart to Evaluate Vapor Retarder Installation.................................... 13 REPORT PLATES & APPENDICES Plate 1: Exploration Location Plan Appendix A: Exploration Logs & Unified Soil Classification System (USCS) Appendix B: Summary Report Geotechnical Engineering Evaluation Village Apartments 2600 North Eagle Road Meridian, Idaho INTRODUCTION STRATA, A Professional Services Corporation (STRATA) has performed our geotechnical engineering evaluation for the proposed Village Apartments community planned at 2600 Eagle Road in Meridian, Idaho. The project site location is illustrated on Plate 1, Exploration Location Plan. STRATA accomplished our services referencing the scope of services presented in our November 6, 2015 proposal. Our evaluation's purpose was to assess subsurface conditions within the proposed project area and to provide geotechnical recommendations to assist project planning, design, and construction. Below, we outline the services accomplished in providing our geotechnical engineering evaluation: 1. Coordinated exploration with the Idaho Utility Notification Center and Mr. Jim Conger, to help reduce the potential for damage to existing subsurface utilities due to exploration. 2. Accomplished subsurface exploration at the site via 6 exploratory test pits extending up to 14 feet below the existing ground surface. Approximate test pit locations are provided on the attached Plate 1. 3. Performed 2 infiltration tests referencing the Idaho Department of Environmental Quality Technical Guidance Manual. 4. Accomplished laboratory testing on select soil samples obtained during exploration referencing ASTM International (ASTM) procedures. 5. Performed engineering analyses to provide geotechnical recommendations for the planned development, including earthwork, foundation, concrete slab-on-grade, pavement and stormwater disposal recommendations. 6. Prepared and provided this geotechnical deliverable including our engineering opinions and recommendations, exploration and laboratory test results. Site exploration plans and illustrative schematics are also provided. PROJECT UNDERSTANDING The proposed development area consists of agricultural land that is relatively flat and has been previously cultivated in row crops. The site is bounded by existing commercial and 8653 West Hackamore Drive, Boise, Idaho 83709 Phone.208.376.8200 Fax.208.376.8201 www.stratageotech.com Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 2 residential development to the north, east and south, and Eagle Road to the west. We understand the approximate 12-acre site is to be developed with 11 residential apartment buildings, 17 garage buildings, an in-ground pool and clubhouse structure. We understand the structures will be 2 to 3 story wood frame construction, with concrete slab-on-grade floors. Structural loading is not available at this time, however, based on our experience with similar projects, we anticipate maximum column loads will be less than approximately 50 kips, with maximum wall loads of up to approximately 2 kips per lineal foot. The development will also include municipal and franchise utilities as well as private asphalt-paved drive aisles and parking. We understand stormwater will be retained and infiltrated on-site via subsurface infiltration beds. STRATA has not reviewed a grading plan for the development, but we anticipate grading will be limited, with cuts and fills of less than approximately 1 to 2 feet. SUBSURFACE EVALUATION PROCEDURES STRATA accomplished subsurface exploration on November 23, 2015 via 6 exploratory test pits extending up to approximately 14 feet below existing ground surface. The approximate exploration locations are illustrated on Plate 1, Exploration Location Plan, which also delineates the proposed development. Test pit locations were established in the field by taping from existing site features. A staff engineer from our office visually evaluated the soil encountered in each test pit and logged the soil profile referencing the USCS. We provide a brief USCS explanation in Appendix A to help interpret the terms on the test pit logs. We also provide individual test pit logs in Appendix A. The test pits were backfilled with the excavated material to the ground surface following the completion of the excavations. We performed in-situ infiltration testing to assist in evaluating stormwater disposal infiltration rates in the gravel subsoil. We accomplished infiltration testing referencing the Idaho Department of Environmental Quality Technical Guidance Manual infiltration test method. www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 3 SUBSURFACE CONDITIONS Subsurface conditions encountered in test pits comprised near surface lean clay and silt overlying cemented silty sand and sandy silt with silty and poorly graded gravel with at depth. We observed limited vegetation and organics in the exploratory test pit up to approximately 12 inches below the ground surface. Beneath the surficial vegetation and organics, we encountered 3 subsurface soil units: 0� Sandy Lean Clay and Sandy Silt: We observed sandy lean clay and sandy silt at the ground surface across the site. We noted clay to be brown, stiff, and moist. We observed silt and clay soil to approximately 1.5 to 3.5 feet in the test pits. 00 Cemented Silty Sand (SM) and Sandy Silt (ML): Underlying lean clay and non- cemented silt, we encountered light brown to reddish-brown, moist, cemented silty sand and sandy silt. We noted weak to moderate calcium carbonate cementation, with cemented soil extending to depths of approximately 5 to 6 feet in select test pit locations. 4- Poorly-Graded Gravel with Sand (GP): Below depths of 3 to 6 feet, we encountered light brown to tan, moist, dense poorly graded gravel alluvium. We observed cobbles of up to 6 to 10 inches in diameter in the gravel alluvium with varying amounts of silt. In select test pits, the poorly graded gravel alluvium is overlain by a limited thickness of silty gravel. Gravel alluvium extended through the termination depth of all test pits. We did not encounter groundwater during exploration. We installed a piezometer in TP-2 to allow for future groundwater monitoring at the project site. LABORATORY TESTING We tested select soil samples obtained during exploration referencing ASTM procedures. Laboratory test results are summarized on the Exploratory Logs in Appendix A and the Summary Report in Appendix B. We used test results to correlate soil design factors such as subgrade modulus and infiltration rates. GEOTECHNICAL OPINIONS AND RECOMMENDATIONS We present the following geotechnical recommendations to assist planning, design and construction of the proposed Village Apartments community planned at 2600 North Eagle Road in Meridian, Idaho as illustrated on Plate 1 attached to this report. This report i4l www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 4 provides specific foundation and other geotechnical design criteria for the development which the structural and civil design and construction teams must review to verify the applicability to the planned structure as design is underway presently. We base our recommendations on the results of our field evaluation, laboratory testing, our experience with similar soil conditions and our understanding of the proposed construction. If design plans change or if the subsurface conditions encountered during construction vary from those observed during our field evaluation, we must be notified to review the report recommendations and make necessary revisions. Earthwork Excavation Characteristics We anticipate site soil may be excavated using conventional excavation techniques. Carefully plan and implement temporary excavations to be sloped, shored, or braced in accordance with the OSHA excavation regulations, Document 29, CFR Part 1926, Occupation Safety and Health Standards— Excavations, Final Rule. Regulations outlined by OSHA provide temporary construction slope requirements for various soil types and slopes up to 20 feet high. Based on our exploration results, we anticipate alluvium encountered at the site is typically classified as Type C soil, which can be temporarily sloped as steep as 1.51-1:1V (horizontal to vertical), when in a dry condition. Due to the potential for varying soil conditions during construction, we recommend earthwork contractors evaluate each slope configuration specific to OSHA guidelines and to seek appropriate professional guidance to create safe and stable excavations. Construction vibrations can cause excavations to slough or cave. We do not recommend stockpiling materials adjacent to or within 10 feet of excavations, which may cause a surcharge and contribute to excavation instability. Ultimately, the contractor is solely responsible for site safety and excavation configurations factoring in water infiltration, construction access, adjacent loading, and other factors that contribute to excavation stability. The earthwork contractor shall plan excavations with water collection points and utilize conventional sumps and pumps to remove nuisance water from runoff, seeps, or precipitation. If site soil excavations are not immediately backfilled, they may degrade when exposed to runoff and require over-excavation and replacement with granular structural fill. We recommend construction activities and excavation backfilling be performed as rapidly as i4l www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 5 possible following excavation to reduce the potential for subgrades to degrade under construction traffic. Establishinq Subgrades We provide the following recommendations for site preparation: Excavate loose backfill from existing test pit locations and replace as structural fill for all test pits located below proposed buildings, flatwork or pavements. +fir Excavate the exposed subgrade to the project design elevations and tolerances. Existing vegetation and organic soil must be completely removed below all foundation, slab and pavement areas. We encountered roots to depths of up to approximately 12 inches during exploration, however, we anticipate stripping depths of 6 inches will be sufficient to remove significant vegetation and organic matter. Scarify and moisture-condition the finished native subgrade below foundations, slabs and pavement areas to within 3 percent of optimum moisture content to at least 8 inches prior to compaction effort. Moisture-conditioning may include aeration or adding moisture. To improve support characteristics, compact subgrade soil to at least 92 percent of ASTM D1557 (Modified Proctor). Earthwork contractors must expect substantial moisture-conditioning and compaction efforts to achieve proper subgrade moisture. If the subgrade is wet at the time of construction and compaction and moisture-conditioning is not practical, STRATA should be contacted to evaluate the use of a woven geotextile, as discussed in this report's Geosynthetics section. STRATA must observe and approve subgrade conditions and we recommend STRATA work with the earthwork and general contractors to help identify fill areas and provide quantity estimates. After preparing subgrades, it is the contractor's sole responsibility to protect subgrades from degradation, freezing, saturation, or other disturbance. Our opinion is careful construction and earthwork procedures will be critical to achieving adequate subgrade preparation and reducing over-excavation. Specifically, these procedures could include, but are not limited to, carefully staging equipment and/or stockpiles, routing construction equipment away from subgrades, and implementing aggressive site drainage procedures to help reduce saturating subgrades during wet weather conditions. As stated above, it is the contractor's responsibility to protect subgrades throughout construction. Subgrade disturbance that occurs due to the contractor's means and methods must be repaired at no cost to the owner. STRATA will remain available to consult with the project team and the contractor as the project moves forward regarding subgrade preparation procedures. i4I www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 6 Structural Fill All fill for this project must be placed as structural fill. Site soil (excluding topsoil containing vegetation and organics) may be re-used as General Structural Fill for site grading provided it meets the requirements in this report. Various imported fill materials will also be required throughout construction. Our recommended material requirements for structural fill are provided, referencing the latest Idaho Standards for Public Works Construction (ISPWC) specifications. Project structural fill products are described in Table 1, below. Table 1: Structural Fill Specifications and Allowable Use Soil Fill Product Allowable Use Material Specifications • Soil must be classified as silt, sand, or gravel (GP, GM, GW, SP, SM, SW, or ML) according to the USCS. General • Site grading, . Soil may not contain particles larger than 6-inches in Structural Fill temporary median diameter. haul/access roads o Soil must consist of inert earth materials with less than 3 percent organics or other deleterious substances (wood, metal, plastic, waste, etc). • Over-excavations, Granular soil improvements, . 6-inch minus granular subbase meeting the latest Structural Fill temporary haul roads, requirements in ISPWC' Section 801-Uncrushed (Granular temporary platforms, Subbase) Granular subbase, Aggregates. eneral structural fill • Foundation and slab Aggregate Base support, soil Course improvements, • Type 1 Crushed Aggregate meeting the latest requirements asphalt pavement in ISPWC Section 802— Crushed Aggregates. section aggregate, general structural fill • Utility pipe bedding . Soil meeting requirements for Type I bedding as stated in Pipe Bedding within 6 inches of the the latest edition of the ISPWCI, Section 305—Pipe pipe invert Bedding. Drainage • Aggregate meeting the latest requirements for 3-inch Drain Aggregate Infiltration features Rock in ISPWC' Section 801-Uncrushed Aggregates. • Soil classified as MH, OH, CL, CH, OL, or PT may not be used at the project site. • Excess moisture does not render a soil unsatisfactory. Contractors must attempt moisture Unsatisfactory conditioning (i.e. wetting or drying) prior to soil disposal. Soil NONE However, soil not moisture conditioned to within 3% of optimum during compaction is unsatisfactory soil and requires additional moisture conditioning. . Any soil containing more than 3 percent(by weight) of organics, vegetation, wood, metal, plastic or other deleterious substances. Idaho Standards for Public Works Construction www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 7 Other than topsoil encountered, the site soil is expected to be suitable for reuse as general structural fill, providing it can meet the criteria presented in Table 1 above and can be properly moisture conditioned for compaction. Reauired Compaction Place structural fill only over subgrades reviewed and approved by STRATA. Never place structural fill over frozen, saturated, or soft subgrades. Fill placed exclusively in landscape areas, not including fill embankments, can be placed as non-structural fill (i.e. landscape fill) providing there are no structures (sidewalk, curbs, utilities, signs, etc.) or embankments planned directly above the landscape fill. Structural fill products must be moisture conditioned to near optimum moisture content as defined by ASTM D1557 and placed in maximum 10-inch-thick, loose lifts. This lift thickness requires compaction equipment with energy ratings of at least 5 tons. If smaller or lighter compaction equipment is used, reduce the lift thickness to meet the compaction and moisture content requirements presented in Table 2: Required Compaction for Designated Project Areas. Table 2: Required Compaction for Designated Project Areas Project Area Required Structural Fill Compactions Product Requirement • In-situ subgrades below the . Existing Native Soil 92% planned structural fill areas • Pavement and slab support aggregate • General structural fill • Foundation soil improvements • Granular subbase 95% • Site grading • Aggregate base • Trench backfillin Relative compaction and moisture content requirement compared to the maximum dry density of the soil as determined by ASTM D1557 (Modified Proctor). Wet Weather/Wet Soil Construction Once the subgrade elevation is achieved, it is the contractor's responsibility to protect the soil from degrading under construction traffic, freezing and/or wet weather. The condition of the subgrade and careful construction procedures are critical to embankment and subsequent foundation and slab stability and long-term performance. We strongly recommend earthwork construction take place during dry weather conditions. The majority of the near surface on-site soil will be susceptible to pumping or rutting from heavy loads such as rubber-tired equipment or vehicles any time of the year. If construction commences before soil can dry after precipitation or during wet periods of the i4 www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: BO15308A Page 8 year (November through April), the contractor must be prepared to achieve project requirements with respect to subgrades and structural fill placement. This may require earthwork to be completed by low pressure, track-mounted equipment that spreads and reduces vehicle load, or other means and methods. Utility Trench Construction Structural fill for utility trench backfill must be placed and compacted to the structural fill requirements presented herein. Loose soil must be removed from the base of utility trenches prior to placing pipe bedding. In addition, if water is encountered, it must be removed from the base of the utility trench before placing pipe bedding. We recommend utility pipes be placed on at least 4 inches of bedding conforming to Table 1 — Pipe Bedding, placed over undisturbed native soil, structural fill or otherwise supported according to the pipe manufacturer's specifications. After bedding the pipe, place structural fill and compact it from the pipe invert to 1 foot above the top of the pipe with tamping bars and/or plate compactors to render the backfill in a firm and unyielding condition. Thoroughly place and compact bedding below pipe haunches or the zone between the pipe invert and the spring line. To accomplish backfilling, the distance between the side of the pipe at the spring line and the trench wall should be at least 12 inches. The remainder of the utility trench should be backfilled in accordance with this report's Structural Fill section. Geotextiles Non-woven geosynthetics are required for drainage facility construction. Additionally, geosynthetic fabrics can facilitate constructability over soft, wet subgrades. Geogrid reinforcement is not expected to be required unless extremely soft subgrades are encountered during construction. If or where required, geotextiles shall meet the minimum properties shown in Table 3 below: www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 9 Table 3: Geotextile Specifications Geosynthetic Type Use Minimum Material Specifications • Grab tensile strength: 120 pounds (ASTM D4632) • Non-Woven • Surrounding drain rock in infiltration . Puncture resistance: 3100 pounds (ASTM D6241) Geosynthetic • Apparent opening size: US Sieve#70 (ASTM D4751) facilities • Permittivity: 1.7 seconds' (ASTM D4491) • Grab tensile strength: 350 pounds (ASTM D4632) • Woven • Soft subgrade • Puncture resistance: 1000 pounds (ASTM D6241) Geosynthetic conditions Apply geosynthetics directly on approved subgrades, taut, free of wrinkles, and over- lapped at least 12 inches. Consult STRATA to review geosynthetic applications or other subgrade improvement alternatives. Foundation Design We recommend shallow foundations bear on native sandy lean clay. Footing design must conform to the following criteria and the current IBC edition. The following foundation design parameters are based on the loads referenced in our Project Understanding and bearing foundations on granular soil improvements as described below. The following text presents our geotechnical recommendations, design requirements, and construction criteria for granular soil improvements and shallow foundations for the proposed building. General We recommend STRATA be retained to observe the foundation system installation including reviewing soil improvements, geosynthetics placement and subgrade compaction prior to placing concrete forms or concrete. Reviewing the soil improvement process and final foundation bearing surfaces helps confirm our allowable bearing pressures and settlement estimates and is an important part of the geotechnical design process. Footings must extend at least 24 inches below the final exterior ground surface to help protect against frost action. Foundations must be structurally designed to conform to the latest edition of the International Building Code (IBC). The foundation bearing pressures presented below can be increased 30 percent to account for transitory live loads such as seismic and wind. In our opinion, long-term live loads such as equipment, fixtures, storage shelving, etc. should be considered in the total dead structural loads for the project. Our analysis utilizes a factor of safety against bearing capacity failure of 3.0 or greater. Settlement estimates and other design criteria are unfactored. Based on the estimated foundation loading conditions, the text below provides recommended design and construction criteria. i14 www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 10 Bearinq Soil We recommend foundations be supported by native sandy lean clay compacted as recommended in this report's Establishing Subgrades section to help provide a uniform bearing surface, improve constructability, and reduce foundation settlements. If granular structural fill must be placed below foundations fill shall extend 1 foot laterally beyond the foundation edges. Design Criteria Foundations constructed on soil improvements as presented in this report may be designed using a maximum allowable bearing pressure of 2,000 pounds per square foot (psf). Mass concrete placed on soil improvements over compacted subgrades can utilize a friction coefficient (fs) of 0.35 to resist lateral loads. This coefficient must be reduced by 1/3 if concrete is not cast directly on soil such as for pre-cast panels. Interior foundations must maintain at least 4 inches of soil cover between top of the footing and the bottom of the concrete slab. Due to their propensity for reflective cracking, thickened slabs should be avoided. Using good construction practices and constructing during good weather, we estimate foundations bearing on subgrades prepared as recommended herein will realize up to 1 inch total and approximately 0.7 inches of differential settlement in a 30-foot span, assuming similarly loaded columns. Our settlement estimates rely on maximum 50 kip column loads and maximum 2 kips per lineal foot wall loads. Foundation loads greater than these should be analyzed for changes in settlement potential. Where water accumulates at the foundation elevation, settlement may be in excess of our estimates and the building tolerances. Therefore, we recommend exterior grading provide adequate drainage away from the building. Seismic Design Criteria STRATA utilized, site soil, geologic data, the project location, the International Building Code (IBC), ASCE - 7 and the National Earthquake Hazards Reduction Program (NEHRP) to establish a Seismic Site Classification of"D" at the project site. We recommend seismic design reference the seismic parameters provided in Table 4 based on the soil conditions and project location. Furthermore, we consider the potential for liquefaction and lateral spread to be low. www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 11 Table 4: Seismic Response Criteria (2012 IBC/ASCE 7)1 Standard Acceleration Site Factor for Modified Acceleration Period (seconds) Coefficients (g) Site Class D Coefficient for Site Class D 0.0 (Peak) PGA= 0.117 FPGA= 1.566 PGAM= 0.183 0.2 (Short) Ss = 0.297 Fa= 1.562 SDS = 0.310 1.0 S1 = 0.104 F = 2.386 SD1 = 0.165 1.Values for location Latitude 43.6294°N and Longitude 116.3506°W Concrete Slabs-On-Grade Aggregate Support Section Concrete slab-on-grade floors subjected to light loading (i.e. interior pedestrian floors) should be supported by at least 4 inches of aggregate base, as defined in Table 1, to provide a leveling course and capillary break for the slab. Aggregate base for slab support shall be placed over a compacted subgrade reviewed by STRATA conforming to the Establishing Subgrades and Structural Fill requirements in this report. Subgrade areas that become soft, loose, wet, or disturbed must be over-excavated to firm soil and replaced with granular structural fill. Place aggregate base and vapor retarders once the majority of under-slab plumbing and utilities are completed. Floor slabs must be structurally designed for the anticipated use and equipment or storage loading conditions. Based on correlations to our field and laboratory test results, if our recommendations are followed, we recommend concrete slab design utilize an allowable modulus of subgrade reaction (k) of 150 pounds per cubic inch (pci). However, if the subgrade is disturbed, wet or unstable, this value can be drastically less. Contrarily, if additional aggregate will be placed below the slab, the modulus of subgrade reaction may be higher. Contact STRATA to provide revised recommendations. Exterior Slab Considerations Exterior slabs-on-grade exposed to higher loading may include dumpster pads, exterior slabs at entryways or other such high-traffic features. The project team should consider using an increased aggregate base support section below these exterior, high- traffic slabs, which is at least 10-inches thick and extends laterally at least 5 feet outside the where heavy equipment may operate. Exterior slabs are susceptible to frost action which can generate substantial frost heave at certain times of the year. The potential for frost heave may not be acceptable at entries, work bays or other critical areas adjacent to the building that will be exposed to i4 www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 12 weather. One approach to provide partial frost protection requires removing 65 percent of material within the frost depth and replacing it with granular structural fill. If this method is employed, the over-excavated soil must be replaced with aggregate base course as specified in the Structural Fill section. Alternatively, if partial frost protection is unacceptable, over-excavation and aggregate base course replacement must be accomplished to the anticipated frost depth (24 inches). Vapor Retarder Use Interior floor slabs may be susceptible to moisture migration caused by subsurface capillary action and vapor pressure. Moisture migration through floor slabs can break down floor coverings. Often, these moisture problems were associated with either no moisture protection below the slab or, alternatively, un- or inadequately sealed sub-slab penetrations that allowed vapor migration and damage to the flooring system. Plumbing penetrations are notoriously problematic for under-slab vapor protection. Vapor retarders must consist of thick, puncture-proof polyethylene sheeting placed immediately below the floor slab. An example of this material is Stego WrapT11, a 15-mil retarder. Alternatively, the vapor retarder may be covered with an additional 2-inch thick layer of clean, coarse sand placed between the crushed surfacing support layer and the concrete slab-on-grade floors. The subject of vapor retarder placement has been widely studied and discussed and a number or opinions regarding their applicable uses and placement exist. Extrapolated from American Concrete Institute (ACI) Figure 3-1 of ACI 302.1 R-04, vapor retarder installation options are outlined in Figure 1: Flow Chart to Evaluate Vapor Retarder Installation, below. www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 13 Figure 1: Flow Chart to Evaluate Vapor Retarder Installation (Adapted from Figure 3-1 of ACI 302.1 R-04) Does the project have a vapor sensitive covering or a humidity controlled area? No Yes Vapor retarder/barrier is required Slabs with vapor Slabs in humidity sensitive coverings controlled areas Will the base materials and slabs be placed with the water-tight roofing system in place?' No Yes FIGURE 1 FIGURE 2f FIGURE 3 Slab t Slab Slab Dry Vapor Dry granular retarder/ granular material barrier material NOTE: 'If granular material is subject to future moisture infiltration,use Figure 2 If Figure 2 is used,a reduced joint spacing,a low shrinkage mix design, or other measures to minimize slab curl will likely be required Form stakes, piping, or other sub-slab penetrations must never penetrate the vapor retarder. Carefully design and construct any vapor retarder penetrations to reduce vapor transport through such penetrations. Where floor coverings or equipment must be protected from damage by moist floor conditions, we strongly suggest a vapor retarder be installed. Even if these recommendations are used, water vapor migration through the concrete floor slab is still possible. Floor covering should be selected accordingly. Manufacturer's recommendations should be strictly followed. Where vapor retarders are utilized, the flooring and concrete slab contractors, as well as the plastic sheeting manufacturer, should be consulted regarding additional slab cure time requirements, latent slab moisture, and/or the potential for slab curling. Pavement Subgrade Preparation and Section Design General The following flexible asphalt pavement section design is provided referencing the American Association of State Highway and Transportation Officials (AASHTO) Guide for Design of Pavement Structures (1993). STRATA estimated traffic loading and design parameters based on our proposed construction and traffic understanding, results from laboratory testing and our understanding of the subsurface conditions. 1% www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 14 Traffic and Subgrade The tables continued on the next page present our traffic loading estimates, geotechnical design parameters, and references as well as the resulting flexible pavement section design recommendations. Table 5: Pavement Design Parameters Design Parameter Value Used References Reliability (R) 90% Estimated Standard Deviation (S) 0.45 AASHTO 1993 Initial Serviceability (PSI) 4.2 Typical regional values Terminal Serviceability (PSI,) 2.1 Typical regional values Traffic Loading 33,000 ESALS' See Table 6 below Design Life 20 years Assumed Resilient Modulus (M) 6,000 psi2 Assumed based on R-value correlations (see paragraph below) Asphalt Layer Coefficient (a,) 0.42 Figure 2.5 AASHTO 1993 Aggregate Base Course 0.12 Figure 2.6 AASHTO 1993 Layer Coefficient (a2) Aggregate Base Course Table 2.4 AASHTO 1993 for "fair" Drainage Coefficient (m2) 1.0 drainage, 1 to 8 percent saturation Granular Subbase Course 0.10 Figure 2.6 AASHTO 1993 Layer Coefficient (a2) Granular Subbase Course Table 2.4 AASHTO 1993 for "fair" Drainage Coefficient (m2) 1.0 drainage, 1 to 8 percent saturation 'Equivalent Single Axle Loads (ESALs). 2Pounds per square inch (psi). Table 6: Traffic Loading Assumptions Pavement Section Traffic Loading Frequency' or s Area Parameters Value Used EALF ESALS Standard-Duty Passenger Vehicles 200 trips per day 0.004 7,000 Section Garbage, Mid Range (parking areas) GVW Trucks 4 trips per day 0.75 26,000 Annual Growth Factor 2.0% Construction TraffiC3 **None** 'One trip is one complete pass by the vehicle. 2Equivalent Axle Load Factor; Loading by one vehicle trip. 3Construction traffic is not included in design. From correlations to index laboratory testing, we estimate the subgrade for proposed asphalt areas will have a resilient modulus (Mr) correlation of approximately 6,000 psi. To help improve subgrade characteristics, the pavement subgrade should be prepared as recommended in this report's Site Preparation section. Subgrades must be shaped (crowned) and graded to facilitate positive drainage and inverted crowns must be avoided. 04 www.stratageotech.com 0 2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 15 Asphalt, Aqqreqate Base Course and Subbase Materials Crushed aggregate base course and granular subbase shall conform to the Structural Fill requirements section, and be placed directly over a properly prepared subgrade. A woven geotextile is an option for constructability during wet and inclement weather and to increase performance at the subgrade and should have material properties and be placed as outlined in this report's Geosynthetics section. We recommend STRATA observe final subgrade preparations, geotextile placement and all aggregate placements. Compact asphalt concrete to between 92 and 96 percent of the maximum density for Superpave mix design. The final traveling surface of asphalt concrete shall meet ITD SSHC 1/2 or 3/4-inch asphalt mix design requirements. Asphalt mix designs and all appropriate aggregate source certificates should be accepted by STRATA at least 5 days prior to initiating asphalt paving. Asphalt construction and final surface smoothness, joints and density should meet ITD specifications. If subgrade conditions appear significantly different during construction, traffic loading conditions change or traffic volumes increase, STRATA should be notified to amend our design accordingly. Pavement Section Thickness STRATA evaluated the pavement sections utilizing the AASHTO pavement design methodology, soil-engineering parameters from previous field and laboratory testing and the estimated traffic-loading conditions. Based on the above pavement design parameters, Table 7 below provides our flexible pavement design recommendations. If traffic loading or subgrade conditions change as design is finalized or during construction, STRATA must review our pavement analyses and resulting sections. Table 7: Standard Asphalt Pavement Section Thickness Asphalt Concrete Aggregate Base Granular Asphalt Pavement Application (inches) (inches) Subbase (inches) Standard Duty Section — Parking 2.5 4 8 The above pavement section assumes the subgrade will be prepared as described in the Establishing Subgrades and Structural Fill report sections. Pavement Maintenance Considerations We recommend crack maintenance be accomplished on all pavement surfaces every 3 to 5 years to reduce the potential for surface water infiltration into the underlying pavement subgrade. Slurry seals and chip seals can extend flexible pavement life and 04 www.stratageotech.com 0 2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: BO15308A Page 16 reduce water infiltration to the subgrade. As asphalt pavements age, brittle/thermal cracking and isolated areas of distress and deterioration are normal and commensurate with pavement design assumptions. Identifying soil fines seeping through cracks can identify subgrade areas that may retain water. These distressed areas should be sealed to help reduce water infiltration. Pavement maintenance and reducing water infiltration to pavement subgrades will slow pavement distress and may extend pavement life. Surface and subgrade drainage are extremely important to the performance of the pavement section. Therefore, we recommend the subgrade, aggregate and pavement surfaces slope at no less than 2 percent to an appropriate stormwater disposal system or other appropriate daylight location that does not impact adjacent properties; higher subgrade slopes improve drainage and pavement performance. Surface irrigation overspray, ponded water, or other water infiltrating the pavement surface must be avoided to the maximum extent practical. Pavement performance will depend upon achieving adequate drainage throughout the section and especially at the subgrade. Water that ponds at the pavement subgrade surface reduces pavement support, can induce heaving during the freeze-thaw process and create pavement distress. Site Drainage Stormwater Disposal We performed infiltration testing within native, poorly graded gravel with silt encountered at depth across the site. We measured an infiltration rate of approximately 20 inches per hour during testing. Considering the relatively permeable gravel soil, we recommend all infiltration facilities extend a minimum of 1 foot into native, poorly graded gravel soil. Approximate excavation depths of 3.5 to 6 feet below existing grade should be anticipated to expose native gravel alluvium. We recommend all subsurface infiltration facilities that extend into poorly graded gravel with silt be designed using an allowable infiltration rate of 8 inches per hour, which includes a factor of safety of 2 or greater. We did not encounter groundwater during our investigation. Groundwater in the site vicinity is primarily related to irrigation, and will fluctuate seasonally. Based on our experience in the area, we estimate typical seasonal high groundwater may occur at an approximate depth of 12 to 14 feet. STRATA will continue to accomplish groundwater monitoring during the irrigation season to evaluate the potential for groundwater fluctuation. i4I www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 17 Exterior Grading Other than areas governed by ADA requirements, we recommend the ground surface outside of any structure be sloped a minimum of 5 percent away for 10 feet to rapidly convey surface water or roof runoff away from foundations. Remaining landscapes should slope at least 2 percent away from structures. Roof downspouts must be provided and connected to a solid pipe placed away from structures and not allowed to infiltrate into the soil underlying the structure. Stormwater should be routed away from disturbed soil areas and should be disposed of in stormwater disposal facilities located at least 20 feet from the proposed building foundations. Irrigation within 10 feet of the buildings is discouraged. ADDITIONAL RECOMMENDED SERVICES Geotechnical Design Continuity The information contained in this report is based on anticipated structural loads and current development plans provided the design team. The final floor elevation, floor configuration, loading conditions, as well as site geometry, can significantly alter our opinions and design recommendations. Specifically, changes in structural design loads and planned site grading may require additional foundation and earthwork evaluations specific to the actual anticipated construction conditions. We should be contacted once final designs are completed to review our opinions and design recommendations contained herein. Plan and Specification Review We recommend STRATA be retained by the project owner to review geotechnical related plan and specification sections prior to issuance of the construction documents for bidding. It has been our experience that having the geotechnical consultants from the design team review the construction documents reduces the potential for errors, and reduces costly changes to the contract during construction. Geotechnical Observation During Construction We recommend STRATA be retained to provide construction observation and testing to document the report recommendations have been followed. Providing these services during construction will help to identify potential earthwork and foundation construction issues, thus allowing the contractor to proactively remedy problems and reduce the potential for errors and omissions. If STRATA is not retained to provide these design verification services during construction, then we will no longer have geotechnical engineer-of-record continuity i4l www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: B015308A Page 18 and cannot be responsible for design or construction errors or omissions. Consistent with the standard of care in the industry, the firm retained to accomplish this work will assume the responsibility as the geotechnical engineer-of-record. EVALUATION LIMITATIONS This geotechnical engineering report has been prepared to assist in planning, design, and construction for the proposed Village Apartments community at 2600 North Eagle Road in Meridian, Idaho. Our scope does not include an engineering evaluation for deep foundations, concrete section design, or shoring design. Variation in subsurface conditions may exist between or beyond our exploration locations, which can necessitate changes to the geotechnical recommendations in this report. Also, changes to the planned development can significantly affect our recommendations. If the improvement plans change from those described herein, we must be notified so that we may make modifications to our recommendations with respect to the modified improvements. If unforeseen conditions are encountered during earthwork, STRATA must be afforded the opportunity to review our recommendations and provide necessary consultation, revision, or modifications to information contained herein. We recommend STRATA be retained to review the final project plans and specifications, to provide geotechnical continuity throughout construction, and to identify any soil variations which could impact our recommendations. Exploration allows observing only a small portion of the site's subsurface conditions. Subsurface variations may not be apparent until construction. We recommend STRATA be retained to provide continuity throughout project design and construction to review site preparations, specifically slab and foundation excavations to verify the conditions encountered in exploration and relied on for design exist in the field and to identify any undocumented fill not encountered during exploration. If subsurface variations exist, they may impact the opinions and recommendations presented in this report, as well as construction timing and costs. This report was prepared for the exclusive use of Conger Management Group and their project design team, for the specific project referenced herein. STRATA cannot be held responsible for unauthorized duplication or reliance upon this report or its contents without written authorization. The geotechnical recommendations provided herein are based on the premise that an adequate program of tests and observations will be conducted by STRATA during construction in order to verify compliance with our i4l www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.All rights reserved. Geotechnical Engineering Evaluation Village Apartments—Meridian ID File: BO15308A Page 19 recommendations and to confirm conditions between exploration locations. Subsurface conditions may vary from the locations explored and the extent of variation may only be known at the time of construction. Where variations occur, it is critical STRATA be afforded the opportunity to modify our report to reflect the site conditions exposed. This acknowledgment is in lieu of all warranties either express or implied. The following plates accompany this report. Plate 1: Exploration Location Plan Appendix A: Exploration Logs and Unified Soil Classification System (USCS) Appendix B: Summary Report www.stratageotech.com ©2015 by Strata,A Professional Services Corporation.Ali rights reserved. LEGEND TP-1 Approximate test pit location observed by STRATA on November 23, 2015. * Standpipe Piezometer Installed in Test Pit. I APPROXIMATE f� ,* SITE BOUNDARY m TP-1 TP-2 fu to X TP-6 VICINITY MAP y NOT TO SCALE a APPROXIMATE SITE LOCATION Hwy 55 M a e slie Dr I c=e�wen `9h GO g e TP-5 ° EXPLORATION LOCATION PLAN 2600 N Eagle Road Meridian, Idaho TP-4 TP-3 Pr .s s 5 9r 0 50 100 200 SCALE: 1 inch = 100 feet sTRaTa f `f=4 A PROFESSIONAL.SERVICES CORPORATION ��Yectri l�.Frow[4-6ce C-7roustd VI, DRAWING DATE:12-2-2015 THIS PLAN ER,TH DELIVERABLE SHOULDSBE READ OCOMPLETELY.N OF THIS UP RNBIS INTENDED TOLE AND THE XHELP VISUALIZE T OF THE ETHE INFORMATION PROVIDED INRABLE CONTAINS ESSENTIAL FTHE DELIVERABLE.E THESE NLOCATIONS AND G THIS PLAN ONFORMATIONR ANY OWERESE HADD PTO EXISTING DRAWING BY:DIMS CHECKED BY:ND PLANS OF THE SITE PREVIOUSLY PREPARED BY OTHERS AND NO CHECK OF ACCURACY,CURRENCY,APPROPRIATENESS,ETC.,OF INFORMATION PROVIDED BY OTHERS WAS PERFORMED,SINCE SUCH CHECKS Client ect No. WERE Nor PART GF STRATA•S SCOPE OF SERVICES, CONGER MANAGMENT ro I BO15308A PLATE:1 REFERENCE: Aerial Image Provided by Google Earth. APPENDIX A Exploration Logs & Unified Soil Classification System (USCS) w C/) N o °, go Remarks WCq o "v o E N Z y EUSCS Description ? ao Note: BGS=Below::1 cc U) o 0 a° a Ground Surface LL PI SANDY LEAN CLAY, (CL)brown,stiff, 0.0 moist Moderate roots and vegetation to about 12 inches BGS. CL 2.5 POORLY GRADED GRAVEL,With Silt, (GM)brown,dense,moist a a ro 0 N 0 m w GM z z 0 U z 5.0 a a J J_ POORLY GRADED GRAVEL,With Sand, N (GP)light brown,dense,moist,with coarse o sand g m 0 m N GP '.O'• N U) q�b H w o �.. �BG o O Percolation test performed at 7.5 feet BGS. Infiltration rate= 7.5 >20 inches per hour p •� measured. .. 15 Test Pit Terminated at 8.0 Feet. N N H 0 c� d U) Client: CONGER MANAGMENT Test Pit Number: TP-1 EXPLORATORY w Project: B015308A Date Excavated: 11-23-2015 Backhoe: CASE 580 Bucket Width: 2' S T FR Wr& TEST PIT LOG A Fro!ds::n Srvcu C .,• r,;,., S-Mxg.'.+y Frcn•rcF c.�rn..wJ�f- Depth to Groundwater: N.E. Logged By: ND Sheet 1 Of 1 y rn Remarks (7 N C'p �N iV' N +�-• N a� Np N C� .�..s. w N Y USCS Description " a N o a N y E P in �? T a o U) o � Note: BGS=Below U' U' o Z o a° a Ground Surface 0.0 LL PI SANDY LEAN CLAY, (CL)brown,stiff, moist Moderate roots and vegetation CL to about 12 inches BGS. SILTY SAND,(SM)reddish brown,dense, moist,moderate cementation • • 2.5 • SM • BG 24.0 29.3 • • • POORLY GRADED GRAVEL,With Sand, 5.0 (GP)reddish tan,dense,moist °�b c� Q.• . w M N ' 0 I] 0] Q w 7.5 z Z p z 4 Z a�' w •. a a' CL a ° W . GP Q. � O a 10.0 o •Q. o m W N Q^ _ m N 0 0 N 0 P D:• a 12.5 Q' an. Piezometer installed to 14 feet o.. BGS. 0 Test Pit Terminated at 14.0 Feet. c� d U) Client: CONGER MANAGMENT Test Pit Number: TP-2 EXPLORATORY w Project: B015308A Date Excavated: 11-23-2015 Backhoe: CASE 580 Bucket Width: 2' S T FR Wr a TEST PIT LOG A 5-11-cu C111•01 1-- S-Mxg.'.+y Frcn•rcF c.�rn..wJ�f- Depth to Groundwater: N.E. Logged By: ND Sheet 1 Of 1 w C/) N o �, go Remarks WCq o "v o E N Z y EUSCS Description ? ao Note: BGS=Below::1 cc U) o 0 a° a Ground Surface LL PI SANDY LEAN CLAY, (CL)brown,stiff, 0.0 moist Moderate roots and vegetation to about 12 inches BGS. CL 2.5 SANDY SILT,(ML)brown,very dense to hard,moist, moderate cementation a a U) W W 0 M o BEG54.0 18.7 m W ML (D z 0 U z 5.0 a a J J_ POORLY GRADED GRAVEL,With Sand, (GP)tan,dense,moist °�b o g w GP Q 0 m N O N Test Pit Terminated at 7.0 Feet. U W O a N N N N H 0 c� d Client: CONGER MANAGMENT Test Pit Number: TP-3 EXPLORATORY w Project: B015308A Date Excavated: 11-23-2015 Backhoe: CASE 580 Bucket Width: 2' S T FR Wr& TEST PIT LOG A Pro!dS:, 5-1v c rw•, S-Mxg.'.+y Frcn•rcF c.�rn..wJ�f- Depth to Groundwater: N.E. Logged By: ND Sheet 1 Of 1 C 0 y �,o _ rn Remarks USCS Description (5 S " 0 E E a m N gi o a y P o �? T m� a o o - Note: BGS=Below `� `� o Z o a° a Ground Surface 0.0 LL PI SANDY SILT, (ML)brown,stiff, moist Moderate roots and vegetation to about 12 inches BGS. ML SANDY SILT,(ML)light brown,medium dense,moist,moderate cementation 2.5 ML a a 0 0 LU LU z 0 U W POORLY GRADED GRAVEL,With Sand 5.0 And Silt,(GP-GM)tan,dense,moist ° a GP- O W GM ° a J J O > O 0 Test Pit Terminated at 6.0 Feet. M 0 07 W O 07 O N_ U) U w O a N N N N H 0 d Client: CONGER MANAGMENT Test Pit Number: TP-4 EXPLORATORY N Project: B015308A Date Excavated: 11-23-2015 STRaTa TEST PIT LOG w Backhoe: CASE 580 Bucket Width: 2' A PROFESSIONAL SERVICES ComoAAn" Depth to Groundwater: N.E. Logged By: ND -r..,NFg..ry F :x. ...w��- Sheet 1 Of 1 w C/) N o �, go Remarks USCS Description " E a N o a N Z y E P o v? T m a o o Note: BGS=Below U) � o Z o 0 a° a Ground Surface 0.0 LL PI SANDY SILT, (ML)brown,stiff, moist Moderate roots and vegetation to about 12 inches BGS. ML SILTY GRAVEL,(GM)brown,medium dense,moist 2.5 GM a a U) W W 0 N Q Lll w. POORLY GRADED GRAVEL,With Sand, a' Percolation test performed at o (GP)brown,medium dense,moist : 5.0 feet BGS. Infiltration rate= g >20 inches per hour Z 5.0 GP Q measured. W w Test Pit Terminated at 5.5 Feet. a J J_ a 0 M O m WW 0 m N O N U) H U W O a N N N N H 0 c� d Client: CONGER MANAGMENT Test Pit Number: TP-5 EXPLORATORY w Project: B015308A Date Excavated: 11-23-2015 Backhoe: CASE 580 Bucket Width: 2' S T FR Wr a TEST PIT LOG A Pro!dS, 5-1v c rw•, S-Mxg.'.+y Frcn•rcF c.�rn..wJ�f- Depth to Groundwater: N.E. Logged By: ND Sheet 1 Of 1 w C/) N o �, go Remarks WCq o "v o E N Z y EUSCS Description ? ao Note: BGS=Below::1 cc U) o 0 a° a Ground Surface LL PI SANDY LEAN CLAY, (CL)brown,stiff, 0.0 moist Moderate roots and vegetation to about 12 inches BGS. CL BG 61.0 15.5 2.5 a POORLY GRADED GRAVEL,With Silt, (GP-GM)brown,medium dense,moist ° W p Q O ro o ° GP-GM <' 0 9? O W z O p zW Test Pit Terminated at 5.0 Feet. 5.0 a CL a W c� J J_ a 0 M L2 O m WW 0 m N O N U) H U W O a N N N N H 0 c� d U) Client: CONGER MANAGMENT Test Pit Number: TP-6 EXPLORATORY w Project: B015308A Date Excavated: 11-23-2015 Backhoe: CASE 580 Bucket Width: 2' S T FR Wr a TEST PIT LOG A Pro!dS:, 5-1v-c rw•, S-Mxg.'.+y A-•rcF c.�rn..wJ�f- � Depth to Groundwater: N.E. Logged By: ND - Sheet 1 Of 1 RAC ADD Standard,ABorders\Bor ig1.og 2011.dwg,�/23/201-1 11:IC:05,AM,DIA"G To PDICpe3 UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GRAPH LETTER TYPICAL NAMES SYMBOL SYMBOL O . . GW Well—Graded Gravel, CLEAN Gravel—Sand Mixtures. GRAVEL GP Poorly—Graded Gravel, GRAVEL O ' Gravel—Sand Mixtures. GRAVEL GM Silty Gravel, Gravel— WITH Sand—Silt Mixtures. FINES GC Clayey Gravel, Gravel— GRAINED COARSE Sand—Clay Mixtures. SOIL 0 0 0 0 0 Well—Graded Sand, CLEAN 0 0 0 0 C SW Gravelly Sand. SAND 0 0 0 0 SP Poorly—Graded Sand, SAND • • • • • • Gravelly Sand. Silty Sand, SAND SM Sand—Silt Mixtures. WITH Clayey Sand, FINES ,•;• SC Sand—Clay Mixtures. Inorganic Silt, Sandy ML or Clayey Silt. SILT AND CLAY Inorganic Clay of Low LIQUID LIMIT CL to Medium Plasticity, LESS THAN 50% Sandy or Silty Clay. OL Organic Silt and Clay of Low Plasticity. FINE GRAINED Inorganic Silt, Mica— SOIL MH ceous Silt, Plastic Silt. SILT AND CLAY Inorganic Clay of High CH Plasticity, Fat Clay. LIQUID LIMIT GREATER THAN 50% OH Organic Clay of Medium to High Plasticity. PT Peat, Muck and Other Highly Organic Soil. BORING LOG SYMBOLS GROUNDWATER SYMBOLS TEST PIT LOG SYMBOLS I Standard 2—Inch OD - Groundwater Split—Spoon Sample After 24 Hours H Baggie Sample ' California Modified 3—Inch (7-3-07) Indicates Date of Bulk Sample OD Split—Spoon Sample Reading H IIRock Core 0 Groundwater RG Ring Sample at Time of Drilling Shelby Tube 3—Inch OD Undisturbed Sample Shorthand Notation: BGS = Below Existing Ground Surface N.E. = None Encountered sTRaTa A PROFESSIONAL.SERVICES CORPORATION F,- m a-1—c71-und OF APPENDIX B Summary Report S T R aT a A PROFESSIONAL SERVICES CORPORATION K-E��rr r�ro.�c H6c� C�rourid Up Summary of Test Results Project: Village Apartments Project Number: B015308A Client: Conger Management Date: 12/8/2015 Test Depth Lab Soil Classification Dry Unit In Situ Passing Atterberg Limits Fines Pit (feet) Number (remarks) Weight, pcf Moisture, % No. 200,% LL PI Class. 2 3-3.5 B01501192A Silty Sand 29.3 24 3 4-4.5 B Sandy Silt 18.7 54 6 1.5-2 C Sandy Lean Clay 15.5 61 8653 West Hackamore Drive, Boise, Idaho 83709 Phone.208.376.8200 Fax.208.376.8201 www.stratageotech.com ©2015 Strata, A Professional Services Corporation. 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