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Home My WebLink AboutCC - Storm Drainage Calcs C �1 I ENGINEERING P . C . � Civil Engineering * Project Management DRAINAGE CALCULATIONS FOR: Horse Meadows Subdivision Meridian,Ada County, Idaho February 29, 2024 �SS�ONAL fNc VCENS � a 235 Q Z`eK�y Zc7 O f 1 OF�paS MYS. EO Prepared for: KB HOME IDAHO, LLC 1299 N. Orchard St, Suite 210 Boise, ID 83702 Sabrina Durtschi (208)-250-6161 Prepared by: CK Engineering, P.C. Jeremy Foster, P.E. 130o E. State St. Ste 102 Eagle, ID 83616 (208)-639-1992 CK Engineering 130o E.State St Suite 102 Eagle,ID 83616 208.869.0590 mobile ebad@ck-engineers.com ENGINEERING P . C . Civil Engineering * Project Management Drainage Narrative for HORSE MEADOWS SUBDIVISION Horse Meadows Subdivision consists of 23 drainage areas that drain to 1 permanent Seepage Bed and 4 permanent bioretention swales along Pine Rd, 8 temporary borrow ditches along Black Cat Rd, 2 borrow ditches along Quarter Horse Dr. and 3 private borrow ditches. Included in this drainage report is the narrative for the 1 permanent Seepage Bed, the 4 permanent bioretention swales along Pine Rd, the 8 temporary borrow ditches along Black Cat Rd, and the two borrow ditches along Quarter Horse Dr and the calculations for all the drainage facilities. The public seepage bed, swales, and borrow ditches will be owned and maintained by the Ada County Highway District (ACHD) and built using ACHD's requested Best Management Practices (BMP's). The 3 private borrow ditches will be maintained by the Horse Meadows homeowners association. The geotechnical engineering report that was referenced as part of this design was created by Atlas Technical Consultants, LLC, dated December 15, 2023. This geotech report was prepared for Alexanders Landing Subdivision, a KB Homes subdivision that touches the southeast corner of Horse Meadow Subdivision. The design infiltration rate used for this project was set at 1"/hr.A Horse Meadows Addendum #1 — Infiltration Testing document (dated February 27, 2024) provided a design infiltration rate of 1.2"/hr. For Horse Meadows subdivision,we have designed all storm drain facilities with a 1"/hr percolation rate. All storm drain facilities will require onsite percolation testing at the location and depth of infiltration in order to verify this percolation rate. Over excavation may be required to reach material that will allow 1"/hr percolation. If over excavation is required, clean pit run may be used as a backfill to get back to grade. If 1"/hr cannot be achieved, the facility will need to be redesigned. Atlas determined that seasonal high groundwater should remain greater than approximately 11 feet below the existing ground elevation. Seepage Trench #i Seepage Trench #1 will be a public, permanent storm drain facility designed per ACHD BMP20. It will accept runoff from drainage areas #1-#6. These areas combine for a total area of 6.02 acres. This results in a too year storm intensity of 2.58 in/hr and a 25 year intensity of 1.85 in/hr. The total weighted C value of a single family subdivision is 0.50. These combined numbers result in a total too year flow of 7.76 CFS to Seepage Bed #1 and a total 25 year flow of 5.57 CFS to Seepage Bed #1. Considering the calculated storm run-off numbers, the required too year storm volume for the Seepage Bed #1 is 10,397 CF. Seepage Bed #1 is to be 3o'Wx6.5'Dx131'L. With a void ratio of 0.4 and design infiltration rate of 1"/hr. This bed will be sufficiently sized. The total time of concentration for this area is calculated at 40.29 minutes. Using a time of CK Engineering 1300 E.State St Suite 102 Eagle,ID 83616 208.869.0590 mobile chad@ck-engineers.com ENGINEERING P E C . Civil Engineering * Project Management concentration of 40 min with an intensity of 1.15 in/hr, 2-1000 gallon sand and grease traps will be required to handle the peak runoff. Please see the attached calculations for Seepage Bed #1. Frontage Borrow Ditches: Black Cat Road Drainage Areas #11-#18 drain to Borrow Ditches #5-#12 respectively. The typical width of the borrow ditch is a total of 18 ft wide with 2 ft wide or 4' wide sand bottoms and 4:1 max side slopes on the road side and varying slopes on the sidewalk side (not exceeding 3:1). Sand windows are installed at the low points of the borrow ditches and sand windows have been sized to drain the too year storm runoff in less than 48 hours. The storage capacity for the borrow ditches have been designed for the too year storm runoff volume. Using DA #14 which has Borrow Ditch #8 as an example, it produces a too year storm runoff volume of 374 cubic feet. The borrow ditch is 50 feet long with a 6 foot wide bottom and has a storage capacity of 613 cubic feet. The sand window is 6' wide by 15' long and with a design infiltration rate of 1"/hr the sand window will drain go% of the too year runoff in 44.88 hours. Frontage Bioretention Swales: Pine Road Drainage Areas #7-#lo drain to 4 bioretention swales along Pine Road. Drainage area #9 containing bioretention Swale #3 is 1o6' long by 8' wide with a bottom too' long by 2' wide. Swale #3's design volume is closest to the too year runoff volume which is why it used as the calculation example for the swales along Pine Road. Drainage area #9 runoff volume for the too year storm event is 291 cubic feet. Taking into account the bottom slope of the road, bioretention Swale #3 has a storage capacity of 293 cubic feet (using the Stage Storage tool in CAD and using the average end area method). The infiltration window in the Swale is 2' wide by too feet long and with a design infiltration rate of 1"/hr the sand window will drain go% of the runoff volume in 15.71 hours. Quarter Horse Borrow Ditches: Drainage Areas #22-#23 drain to Borrow Ditches #16-#17 respectively. The storage capacity for the borrow ditches have been designed for the too year storm runoff volume. Using DA #23 which has Borrow Ditch #17 as an example, it produces a too year storm runoff volume of 44 cubic feet. Borrow ditch #17 has a storage capacity of 81.59 cubic feet. The sand window is 10 SF with a design infiltration rate of 1"/hr, the sand window will drain go% of the too year runoff in 47.52 hours. Attached: 1. Storm drain calculations for Horse Meadows Sub. 2. 11"x17" colored drainage area exhibit for Horse Meadows Sub. 3. Geotechnical Engineering Report —Alexanders Landing Subdivision 4. Addendum #1 — Infiltration Testing — Horse Meadows Subdivision End of Narrative CK Engineering 13oo E.State St Suite 102 Eagle,ID 83616 208.869.0590 mobile chad@ck-engineers.com ck-engineers.com ;C ENGINEERING P . C . Civil Engineering * Project Management DRAINAGE CALCULATIONS CK Engineering 13oo E.State St Suite 102 Eagle,ID 83616 208.869.0590 mobile chad@ck-engineers.com 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. User input in yellow cells. 1 Project Name SEEPAGE BED#1-DRAIN AREA#1.6 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) Click to Show More Subbasins n 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 97,194 38,747 38,887 40,217 7,032 40,005 Acres 6.02 6 Determine the Weighted Runoff Coefficient(C) 0.50 0.50 0.50 0.50 0.50 0.50 C=[(C1xA1)+(C2xA2)+(CnxAn))/A Weighted AvgJ 0.50 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User calculate min to Min. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"t 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(O (�Peak) +peak 7.76 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 10,397 ft 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 Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Industrial and Commercial Light areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 6,498 ft, Heavy areas 0.90 Parks,Cemeteries 0.10-0.25 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) CIS 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 Basin Foreba V 1040 ft, .95 Y , Concrete 0 0.95 Pr imary Treatment/Storage Basin V 9,357 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Gravel Volume Without Sediment Factor See BMP 20 Tab V 10,397 ft' _ ( ) Soil 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 O. Steep:>6% 0.13 0.18 0.23 0. Adapted from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\SEEPAGE BED#1 2-15-24 2/27/2024,2:33 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name SEEPAGE BED 111-DRAIN AREA#1-6 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) Click to Show More Subbasins n 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 97,194 38,747 38,887 40,217 7,032 40,005 Acres 6.02 6 Determine the Weighted Runoff Coefficient(C) 0.50 0.50 0.50 0.50 0.50 0.50 C=[(C1xA1)+(C2xA2)+(CnxAn))/A Weighted Avg1 0.50 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"( 8 Determine the average rainfall Intensity(i)from IDF Curve based on Tc i 1.85 it hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) max 5.57 cis Urban neighborhoods 0.50-0.70 Residential Single Family 0.35-0.50 10 Calculate total runoff vol(V)(for sizing primary storage) V 7,473 ft 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 6,498 ft Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,Cemeteries o.10-0.25 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 747 fta Concrete 0.95 Primary Treatment/Storage Basin V 6,725 fta Brick 0.95 Subsurface Storage Roofs 0.95 Volume Without Sediment Factor See BMP 20 Tab V 7,473 fta Gravel 0.75- - _ — _ ( ) Fields:Sandy soil Soil Type slope A B C D Flat:0-2% 0.04 0.07 1 0. Average:2-6% 0.09 0.12 1 0. Steep`6% 0.13 0.18 0.23 O. Adapted from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\SEEPAGE BED 41 2-15-24 2/27/2024,2:33 PM Version 10.0,May 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 CLV"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 SEEPAGE BED#1-DRAIN AREA k1-6 2 Enter number of Seepage Beds(25 max) 1 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.50 Link to: [Q.v� Q,V TR55 5 Area A(Acres) 6.02 acres 6 Approved discharge rate(if applicable) 0.00 cfs 7 Is Seepage Bed in Common Lot? Yes V 10,397 it, 0%Sediment 8 Set Total Design Width of All Drain Rock W 30.0 ft 9 Set Total Design Depth of All Drain Rock D 6.5 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 1.00 in/hr 12 Size of WQ Perf Pipe(Pert 1800) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 3601),REQD if Q300>3.3 cfs in 14 Calculate Total Storage per Foot Spf 79.4 ft,/ft 15 Calculate Design Length L 131 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 131 ft 17 Variable Infiltration Window W SWW 30.0 it 18 Time to Drain 28.6 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 131 261 it 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAx,/(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 it 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 it, 9 Volume Infiltration Vperc 0 ft3/hr 10 Time to Drain hours 90%volume in 48-hours minimum D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOGS\DRAI NAG E CALCS\SEEPAGE BED#12-15-24 2/28/2024,8:09 AM Version 10.0,May 2018 TIME OF CONCENTRATION PROJECT: Horse Meadows Subdivision BASIN: Seepage Bed#1 (D.A.s#1-6) OVERLAND SHEET FLOW fT11: 0.007(nL)0`8 , WHERE: n = 0.24 Tt — P o;So.a L1= 116 / 1 .: l / P2= 1.2 where: s= 0.0127 Tt = travel time(hr), n = Manning's rouglness coefficient T1 (hrs)= 0.524 L = flow length(ft) P., = 2-year,24-hour rainfall(in) T1 (min)= 31.47 s = slope of hydraulic grade line (land slope,ft/ft) GUTTER CONCENTRATED FLOW: s2= 0.004 V 20..328(�)"', , WHERE: V2= 1.29 L2= 592 Tz= L2/V2 T2 (s)= 460.4655 T2(min)= 7.67 CHANNEL/PIPE FLOW: (T3) Pipe D(in)= 12 ? 1 V_ 1.491•3s2 , WHERE: Ac (ft)= 0.79 n Pw (ft)= 3.14 where: r= 0.25 V = average velocity(ft/s) s= 0.0002 r= hydraulic radius(ft)and is equal to a/p,,. n= 0.012 a= cross sectional flow area(fY) V3= 0.73 p,,.= wetted perimeter(ft) s= slope of the hydraulic grade line(channel L3= 50 slope,ft/ft) n= Manning's roughness coefficient for open channel flow. T3(s)= 68.73 T3(min)= 1.15 T3 = L3/\/3 TOTAL TIME OF CONCENTRATION (T1+T2+T3) TC= 40.29 min TIME I in hr TIME I in hr TIME I in hr 10 min 2.58 50 min 1 12 hr 0.16 15 min 2.18 1 hr 0.96 24 hr 0.1 20 min 1.81 2 hr 0.54 30 min 1.51 3 hr 0.4 40 min 1.15 6 hr 0.25 100 YR STORM INTENSITY GIVEN WITH TIME OF CONCENTRATION 40 MIN 1.15 (IN/HR) WEIGHTED RUNOFF COEFFICIANT PEAK DESIGN STORM RUNOFF C= 0.5 Q= c(I)(A) DRAIN AREA SIZE SF SIZE AC INTENSITY C BASIN PEAK RUNOFF CATCH BASIN DA#1 97194 2.231 1.15 0.5 1.28 cfs CB#1 DA#2 38747 0.890 1.15 0.5 0.51 cfs CB#2 DA#3 38887 0.893 1.15 0.5 0.51 cfs CB#3 DA#4 40217 0.923 1.15 0.5 0.53 cfs CB#4 DA#5 7032 0.161 1.15 0.5 0.09 cfs CB#5 DA#6 40005 0.918 1.15 0.5 0.53 cfs CB#6 TOTAL: 262082 6.017 1.15 0.5 3.46 cfs 25 YR STORM INTENSITY GIVEN WITH TIME OF CONCENTRATION 40 MIN 0.82 (IN/HR) WEIGHTED RUNOFF COEFFICIANT PEAK DESIGN STORM RUNOFF C= 0.5 Q= c(I)(A) DRAIN AREA SIZE SF SIZE AC INTENSITY C BASIN PEAK RUNOFF CATCH BASIN DA#1 97194 2.231 0.82 0.5 0.91 cfs CB#1 DA#2 38747 0.890 0.82 0.5 0.36 cfs CB#2 DA#3 38887 0.893 0.82 0.5 0.37 cfs CB#3 DA#4 40217 0.923 0.82 0.5 0.38 cfs CB#4 DA#5 7032 0.161 0.82 0.5 0.07 cfs CB#5 DA#6 40005 0.918 0.82 0.5 0.38 cfs CB#6 TOTAL: 262082 6.017 1.15 0.5 2.47 cfs ACHD Calculation Sheet for Sand/Grease Traps 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 Horse Meadow-Seepage Bed#1-Drainage Areas 1-2 2 Enter number of Sand/Grease Traps(25 max) 1 Number of Peak Flow Baffle Throat Velocity Is the Vault Size Spacing width Area(ftz) 0.5 fps Velocity S/G Traps Q-cfs inch inch max. ok? 1000 G 1 1.79 29 48 9.67 0.19 Reference for Throat widths(inch) Boise ADS Vault Lar-ken WQU, BMP 16 1000 G 48.0 50.5 n/a 1500 G 60.0 61.5 n/a WQU1000 n/a n/a 60 WQU1500 n/a n/a 60 D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\SEEPAGE BED#1 2-15-24 3/6/2024,4:20 PM Version 10.0, May 2018 ACHD Calculation Sheet for Sand/Grease Traps 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 Horse Meadow-Seepage Bed#1-Drainage Areas 3-6 2 Enter number of Sand/Grease Traps(25 max) 1 Number of Peak Flow Baffle Throat Velocity Is the Vault Size Spacing width Area(ftz) 0.5 fps Velocity S/G Traps Q-cfs inch inch max. ok? 1000 G 1 1.67 29 48 9.67 0.17 Reference for Throat widths(inch) Boise ADS Vault Lar-ken WQU, BMP 16 1000 G 48.0 50.5 n/a 1500 G 60.0 61.5 n/a WQU1000 n/a n/a 60 WQU1500 n/a n/a 60 D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\SEEPAGE BED#1 2-15-24 3/6/2024,4:19 PM Version 10.0, May 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. User input in yellow cells. 1 Project Name SWALE#1-DRAIN AREA#7 2 Is area drainage basin map provided? YES (map must be included with stormwoter calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins n 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 2,716 Acres 0.06 6 Determine the Weighted Runoff Coefficient(C) 0.71 C=[(C1xA1)+(C2xA2)+(CnxAn)J/A Weighted Avgl 0.71 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 'user Calculate min [10 Min. Estimated Runoff Coefficients for Various Surfact Type of Surface Runoff Coefficients"( 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc 1 2.58 in hr Business r� Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) Qpeak 0.11 cfs urban neighborhoods 0.50-0.70 Residential 50 10 Calculate total runoff vol(V)(for sizing prima storage) V 153 ft Single Family 0.60-0.75 primary g ) 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) Vrr 96 W Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,cemeteries 0.20-0.25 Playgrounds 0. 0-0.35 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 15 ft' Concrete 0.95 Primary Treatment/StorageBasin V 138 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Gravel _ _ 0.75 _ Volume Without Sediment Factor(See BMP 20 Tab) V 153 ft' 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 D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALLS\BORROW DITCH41-2-15-24 3/7/2024,3:21 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name SWALE#2-DRAIN AREA#8 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) Click to Show More Subbasins n 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 2,740 Acres 0.06 6 Determine the Weighted Runoff Coefficient(C) 0.71 C=](C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.71 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"( 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc 1 2.58 in hr Business Downtown areas 0.70-0.95 (� y Calculate the Post-Development peak discharge(QPeak) -p..k 0.12 cfs Urban neighborhoods 0.50-0.70 Residential 3 Single Family 0.35-0.50 10 Calculate total runoff vol(V)(for sizing primary storage) V 154 ft 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) V„ 96 it' Heavy areas 0.90 Parks 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs ,cemeteries s Playgrounds 0.20-0.35 0.10-0.2 Railroad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin streets Asphalt 0.95 Basin Foreba V 15 it,Y Concrete 0.95 Primary Treatment/Storage Basin V 139 it, Brick 0.95 Subsurface Storage Roofs 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 154 it, Gravel 0.75 Fields:Sandy soil Soil Type Slope A B C Flat:0 -21 0.04 0.07 0.1"10 Average:2-6% 0.09 0.12 0.1 Steep:>6% 0.13 0.18 0.23 Adapted from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCH#2-2-15-24 3/7/2024,3:20 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name SWALE S3-DRAIN AREA#9 2 Is area drainage basin map provided? YES (map must he 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) Click to Show More Subbasins Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 S 6 7 8 9 30 5 Area of Drainage Subbasin(SF or Acres) SF S,165 Acres 0.12 6 Determine the Weighted Runoff Coefficient(C) 0.71 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.71 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"( 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc 1 2.58 in hr Business Downtown areas 0.70-0.95 y Calculate the Post-Development peak discharge(QPeak) Qp,ak 0.22 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 291 it, 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 tt- Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,cemeteries 0.20-0.25 Playgrounds 0. 0-0.35 Railroad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin streets AsphaBasin Foreba V 29 ft' Concrete 0.95 Y Concrete 0.95 Primary Treatment/Storage Basin V 262 ft' Brick 0.95 Subsurface Storage Roofs 0. fl` Gravel __ _ 0.75 5 Volume Without Sediment Factor(See BMP 20 Tab) V 291 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 D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCHff3-2-15-24 3/7/2024,3:21 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name SWALE q4-DRAIN AREA#10 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) Click to Show More Subbasins n Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 30 5 Area of Drainage Subbasin(SF or Acres) SF 3,999 Acres 0.09 6 Determine the Weighted Runoff Coefficient(C) 0.73 C=((C1xA1)+(C2xA2)+(CnxAn)J/A Weighted Avgl 0.73 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"( 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc 1 2.58 in hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) Qpeak 0.17 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 232 ft 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) Vrr 145 ft Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,Cemeteries 0.10-0.25 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 Foreba V 23 ft' Y Concrete 0.95 Primary Treatment/Storage Basin V 208 ft' Brick 0.95 Subsurface Storage Roots 0.75 Volume Without Sediment Factor See BMP 20 Tab V 232 it, Fields: _ _ _ Soil _ ( ) Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 Soli 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 0. Adapted from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCHH4-2-15-24 3/7/2024,3:21 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name BARROW DITCH q5-DRAIN AREA tl11 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins 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 7,299 Acres 0.17 6 Determine the Weighted Runoff Coefficient(C) 0.90 C=((C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.90 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User calculate min 60 Min. Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients"( 8 Determine the average rainfall Intensity(I)from IDF Curve based on Tc 1 2.58 in hr Business Downtown areas 0.70-0.95 n 9 Calculate the Post-Development peak discharge(QPeak) +peak 0.39 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 521 ft 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 1(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 326 ft, Heavy areas 0.90 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 Foreba V 52 it,Y Concrete 0.95 Primary Treatment/Storage Basin V 469 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Gravel Volume Without Sediment Factor See BMP 20 Tab V 521 ft' ( ) Soil 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 D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCH45-2-15-24 2/27/2024,2:57 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name BARROW DITCH 116-DRAIN AREA#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 4 Enter number of storage facilities(25 max) Click to Show More Subbasins n Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 30 5 Area of Drainage Subbasin(SF or Acres) SF 3,650 Acres 0.08 6 Determine the Weighted Runoff Coefficient(C) 0.90 C=((C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avgl 0.90 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 1 User Calculate min 110 Min. Estimated Runoff Coefficients for Various Surfact - Type of Surface Runoff Coefficients"< 8 Determine the average rainfall intensity(1)from IDF Curve based on Tc i Busi 2.58 in hr ness r1 Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) Opezk 0.19 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 261 ft 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 tight areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr, 163 ft Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,Cemeteries 0.10-0.25 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 Foreba V 26 it,Y Concrete 0.95 Primary Treatment/Storage Basin V 235 it' Brick 0.95 Subsurface Storage Roofs 0.95 Gravel Soil_ Volume Without Sediment Factor See BMP 20 Tab it ( ) V 261 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 D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCHH6-2-15-24 2/27/2024,2:58 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name BARROW DITCH N7-DRAIN AREA#13 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) Click to Show More Subbasins n Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 S Area of Drainage Subbasin(SF or Acres) SF 2,771 Acres 0.06 6 Determine the Weighted Runoff Coefficient(C) 0.90 C=[(C1xA1)+(C2xA2)+(CnxAn))/A Weighted Avgl 0.90 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 user calculate min [10 Min. Estimated Runoff Coefficients for Various Surfau Type of Surface Runoff Coefficients"( 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc 1 2.58 in hr Business (� Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(ClPeak) Qp.k 0.15 cfs Urban neighborhoods 0.50-0.70 Residential a Single Family 0.35-0.50 10 Calculate total runoff vol(V)(for sizing primary storage) V 198 ft 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 tight areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) V,r 124 ft Heavy areas o.90 0.10.0.25 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,CemeteriesPlaygrounds 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 Basin Foreba Y V 20 It, Concrete 0.95 0.95 Primary Treatment/Storage Basin V 178 It, Brick 0.95 Subsurface Storage Roofs 0.95 Volume Without Sediment Factor See BMP 20 Tab V 198 it, Gravel_ 0.75 ( ) 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 D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOGS\DRAINAGE CALCS\BORROW DITCHk7-2-15-24 3/6/2024,2:11 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name BARROW DITCH q8-DRAIN AREA N14 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) Click to Show More Subbasins ❑ Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 30 5 Area of Drainage Subbasin(SF or Acres) SF 5,244 Acres 0.12 6 Determine the Weighted Runoff Coefficient(C) 0.90 C=[(C1xA1)+(C2xA2)+(CnxAn)[/A Weighted Avg 0.90 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 user Calculate min i10 Min. Estimated Runoff Coefficients for Various Surface - 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 V Calculate the Post-Development peak discharge(QPeak) QGeak 0.28 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 374 ft 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, 234 ft' Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,cemeteries 0.ygrou nds 0.20-0.0-0.35 Pla 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/Storage Basin V 337 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 Volume Without Sediment Factor See BMP 20Tab) V 374 ft' --___ - ( Fields:Sandy soil Soil Type Slope A 8 C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>60/, 0.13 0.18 0.23 0. Adapted from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCH48-2-15-24 3/6/2024,2:11 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name BARROW DITCH ft9-DRAIN AREA#15 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) Click to Show More Subbasins ❑ 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 3,653 Acres 0.08 6 Determine the Weighted Runoff Coefficient(C) 0.90 C=((C1xA1)+(C2xA2)+(CnxAn))/A Weighted AvgJ 0.90 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User calculate min i10 Min. Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients"( 8 Determine the average rainfall Intensity(1)from IDF Curve based on Tc i 2.58 in hr Business Downtown areas 0.70-0.95 r� 9 Calculate the Post-Development peak discharge(QPeak) Qpe* 0.19 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 261 ft 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 Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Industrial and CommercialLight areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vr, 163 ft' Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,Cemeteries 0.10-0.25Playgrounds 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 26 It, concrete 0.95 Primary Treatment/StorageBasin V 235 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Volume Without Sediment Factor See BMP 20Tab V 261 ft' -- _-_ ( ) Gravel 0.75 Fields:Sandy soil Soil Type Slope A B t-.1 D Flat:0-2% 0.04 0.07 1 0.Average:2-6% 0.09 0.12 5 O.Steep:>6% 0.13 0.18 23 O. Adapted from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALLS\BORROW DITCH49-2-IS-24 3/6/2024,2:11 PM Version 10.0,May 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. Ca�gul�te Qos �@y@{ppment Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name BARROW DITCH#10-DRAIN AREA#16 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) Click to Show More Subbasins n 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 3,645 Acres 0.08 6 Determine the Weighted Runoff Coefficient(C) 0.90 C=[(C1xA1)+(C2xA2)+(CnxAn))/A Weighted Avg1 0.90 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 user calculate min [10 Min im Estimated Runoff Coefficients for Various Surfact Type of Surface Runoff Coefficients"t 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) QP�A 0.19 cfs Urban neighborhoods 0.50-0.70 Residential 3 Single Family 0.35-0.50 10 Calculate total runoff vol(V)(for sizing primary storage) V 260 ft 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 tight areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) V„ 163 ft Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,Cemeteries 0.10-0.25Playgrounds 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 Foreba V 26 ft' Y Concrete 0.95 Primary Treatment/Storage Basin V 234 ft' Brick 0.95 Subsurface Storage Roofs 0. Gravel 0.75 5 Volume Without Sediment Factor See BMP 20Tab) V 260 ft' —--- - - ( 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 D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCH#10-2-15-24 3/6/2024,2:13 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name BARROW DITCH 811-DRAIN AREA#17 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) Click to Show More Subbasins n 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 3,572 Acres 0.08 6 Determine the Weighted Runoff Coefficient(C) 0.90 C=((C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.90 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min [lo Min. Estimated Runoff Coefficients for Various Surfact Type of Surface Runoff Coefficients"( 8 Determine the average rainfall Intensity(1)from IDF Curve based on Tc I Bust 2.58 in hr ness r1 Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) Qpeak 0.19 cfs Urban neighborhoods 0.50-0.70 Residential 50 10 Calculate total runoff vol(V)(for sizing prima storage) V 255 ft single Family 0.60-0.75 primary 8 ) 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 1(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) Vrr 159 W Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,cemeteries 0.10-0.25 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 26 ft' Concrete 0.95 Primary Treatment/StorageBasin V 230 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Tab ft'Volume Without Sediment Factor Gravel 0.75 See BMP 20 - ( ) V 255 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 D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCHN11-2-15-24 3/6/2024,2:13 PM Version 10.0,May 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize All 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 BARROW DITCH#12-DRAIN AREA#18 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) Click to Show More Subbasins ❑ 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 1,993 Acres 0.05 6 Determine the Weighted Runoff Coefficient(C) 0.90 C=((C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.90 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"( 8 Determine the average rainfall Intensity(i)from IDF Curve based on Tc 1 2.58 in hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) beak 0.11 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 142 ft 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) V 89 fY Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,Cemeteries 6.10-0.25 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 14 ft' concrete 0.95 Primary Treatment/Storage Basin V 128 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 142 ft' Gravel 0.75 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. Steel 0.13 0.18 0.23 0. Adapted from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCH#12-2-21-24 3/6/2024,2:14 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name PRIVATE BARROW DITCH#13-DRAIN AREA#19 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) Click to Show More Subbasins ❑ Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 S Area of Drainage Subbasin(SF or Acres) SF 1,417 Acres 0.03 6 Determine the Weighted Runoff Coefficient(C) 0.64 C=[(C1xA1)+(C2xA2)+(CnxAn))/A Weighted AvgJ 0.64 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"( 8 Determine the average rainfall intensity(1)from IDF Curve based on Tc 1 2.58 In hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(Cl max 0.05 cfs Urban neighborhoods 0.50-0.70 Residential 50 10 Calculate total runoff vol(V)(for sizing prima storage) V 72 ft Single Family 0.60-0.75 primary g ) 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) V 45 ft' Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) Parks,Cemeteries 0.10-0.25 cfs playgrlroounds 0.20-0.35 Raiad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin streets Asphalt 0.95 Basin Foreba V 7 ft' Y Concrete 0.95 Primary Treatment/Storage Basin V 65 fta Brick 0.95 Subsurface Storage Roofs 0.95 Gravel_____ 0.75 (See( ) Fields: Volume Without Sediment Factor S BMP 20Tab V 72 fta - -- Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.31 O. Average:2-6% 0.09 0.12 0.15 0. Steel0.13 0.18 0.23 0. Adapted from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCH#13-2-22-24 3/6/2024,2:14 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name PRIVATE BARROW DITCH q14-DRAIN AREA N20 2 Is area drainage basin map provided? YES (map must be included with starmwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins n 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 1,426 Acres 0.03 6 Determine the Weighted Runoff Coefficient(C) 0.62 C=((C1xA1)+(C2xA2)+(CnxAn))/A Weighted AvgJ 0.62 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 user calculate min Cto Min. Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients"( 8 Determine the average rainfall Intensity(1)from IDF Curve based on Tc 1 2.58 in hr Business r� Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) Ope,k 0.05 ds Urban neighborhoods 0.50-0.70 Residential Single Family 0.35-0.50 10 Calculate total runoff vol(V)(for sizing primary storage) V 70 ft 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) V, 44 ft' Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,cemeteries 0.10-0.25 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 Foreba V 7 fts Y Concrete 0.95 Primary Treatment/StorageBasin V 63 fta Brick 0.95 Subsurface Storage Roofs 0.95 Gravel 0.75 (See Volume Without Sediment Factor S BMP 20 Tab V 70 ft' ( ) 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 o. Steep:>6% 0.13 0.18 0.23 0. Adapted from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCH#14-2-22-24 3/6/2024,2:14 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name PRIVATE BARROW DITCH p15-DRAIN AREA#21 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins n 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 2,777 Acres 0.06 6 Determine the Weighted Runoff Coefficient(C) 0.62 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.62 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 user Cakuiate min (10 Min. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"t 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(Cl weak 0.10 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 137 ft Multi-family 0.60-0.75 V=Cl(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 85 ft' Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) CIS Parks,Cemeteries 0.10-0.25 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 Foreba V 14 ft' Y Concrete 0.95 Primary Treatment/Storage Basin V 123 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Volume Without Sediment Factor(See BM 20 Tab) V 137 ft' Gravel 0.75 Fields:Sandy soil Soil Type Slope A B C D Flat:O-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 D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCHg15-2-22-24 3/6/2024,2:15 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name BARROW DITCH Alb-DRAIN AREA 822 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 2S-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins n Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 30 5 Area of Drainage Subbasin(SF or Acres) SF 1,370 Acres 0.03 6 Determine the Weighted Runoff Coefficient(C) 0.90 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.90 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(1)from IDF Curve based on Tc 1 2.58 in hr Business Downtown areas 0.70-0.95 n 9 Calculate the Post-Development peak discharge(QPeak) +peak 0.07 cis Urban neighborhoods 0.50-0.70 Residential Single Family 0.35-0.50 10 Calculate total runoff vol(V)(for sizing primary storage) V 98 it 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) V 61 fY Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,cemeteries 0.10-0.25 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 Foreba V 10 ft, Y Concrete 0.95 Primary Treatment/Storage Basin V 88 ft' Brick 0.95 Subsurface Storage Roofs 0. _Gravel 0.75 5 Volume Without Sediment Factor(See BMP 20 Tab) V 98 ft' 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 O. Steep:>6% 0.13 0.18 0.23 0. Adapted from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALLS\BORROW DITCHft16-2-21-24 3/6/2024,2:15 PM Version 10.0,May 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. User input in yellow cells. 1 Project Name BARROW DITCH 017-DRAIN AREA 023 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) Click to Show More Subbasins ❑ 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 610 Acres 0.01 6 Determine the Weighted Runoff Coefficient(C) 0.90 C=((C1xA1)+(C2xA2)+(CnxAn))/A Weighted Avg1 0.90 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User calculate min [to Min. Estimated Runoff Coefficients for Various Surface - Type of Surface Runoff Coefficients"( 8 Determine the average rainfall Intensity(1)from IDF Curve based on Tc 1 2.58 in hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) Clp aA 0.03 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 44 ft 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 27 ft' Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,Cemeteries 0.10-0.25 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 4 ft' concrete 0.95 Primary Treatment/Storage Basin V 39 ft' Brick 0.95 Subsurface Storage Roofs 0.95Gravel 0.75 Volume Without Sediment Factor(See BMP 20 Tab) V 44 ft' 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% da 0.13 0.18 0.23 0. pled from ASCE D:\KB Homes\HORSE MEADOWS-MERIDIAN\DOCS\DRAINAGE CALCS\BORROW DITCH417-2-21-24 3/6/2024,2:15 PM Version 10.0,May 2018 ENGINEERING P . C . Civil Engineering * Project Management DRAINAGE EXHIBIT CK Engineering 130o E.State St Suite 102 Eagle,ID 83616 208.869.0590 mobile ebad@ck-engineers.com N W E S PINE RD. 0 100' 200' _DA#10 —DA#9 DA#8 DA#7 — AI SCALE 1" = 100' DA#11 / SEEPAGE BED #1 DA#12 DA#1 = 97,194 SF - CB#1 DA#2 DA#2 = 38,747 SF - CB#2 DA 4 DA#3 = 38,887 SF - CB#3 DA#13 # DA#3 / ' DA#4 = 40,217 SF - CB#4 DA#5 = 7,032 SF - CB#5 DA#6 = 40.005 SF - CB#6 TOTAL = 262,082 SF DA#14 _ CB#1 BORROW DITCHES U Y DA#15 DA#7 = 2,716 SF - SWALE #1 DA#8 = 2,740 SF - SWALE #2 CB#3 CB#21I/ DA#10 = 3,999 SF - SWALE #4 DA#16 C3#4 DA#11 = 7,299 SF - BORROW DITCH #5 DA#12 = 3,650 SF - BORROW DITCH #6 DA 17 DA#1 DA#13 = 2,771 SF - BORROW DITCH #7 # DA#14 = 5,244 SF - BORROW DITCH #8 CB#5.,.; i DA#15 = 3,653 SF - BORROW DITCH #9 # T-;. . . DA#5 DA#16 = 3,645 SF - BORROW DITCH #10 DA 18 DA#21 w.. rEN' ' DA#17 = 3,572 SF - BORROW DITCH #11 DA#18 = 1,993 SF - BORROW DITCH #12 _ DA#19 = 1,417 SF - PRV. BORROW DITCH #13 DA#19 DA#22 CB#6 DA#20 = 1,426 SF - PRV. BORROW DITCH #14 DA 20 DA 23 — -\ — DA#21 = 2,777 SF - PRV. BORROW DITCH #15 # # ' DA#6 In > DA#22 = 1,370 SF - BORROW DITCH #16 �rA DA#23 = 610 SF - BORROW DITCH #17 F HEC HORSE MEADOWS SUBD V S ON REVISIONS: CK BY: AKB CHECKED BY: csK CK ENGINEERING M E R D A N D A H 0 83642 D R AN A G E AREAS DA E D G E. DRAINAGE AREAS? 24 1300 E. STATE ST., SUITE 102 EAGLE, ID 83616 PHONE 208-639-1992 D I R: o:\Ka wmEs\xoFm KE-uri+ov++\ac-owc Dn ENGINEERING P . C . Civil Engineering * Project Management GEOTECHNICAL REPORT CK Engineering 13oo E.State St Suite 102 Eagle,ID 83616 208.869.0590 mobile cbad@ck-engineers.com LA. � w . lk vw r ' J fT J r k I' GEOTECHNICAL INVESTIGATION ALEXANDERS LANDING SUBDIVISION 4575 West Quarter Horse Lane Meridian, ID PREPARED FOR: Sabrina Durtschi KB Home Idaho, LLC 1414 West Bannock Street Boise, ID 83702 PREPARED BY: Atlas Technical Consultants, LLC December 15, 2023 2791 South Victory View Way B232086g Boise, ID 83709 �/��M" ■ �TrT-G tv— 1. December 15, 2023 Atlas No. B232086g Sabrina Durtschi KB Home Idaho, LLC 1414 West Bannock Street Boise, ID 83702 Subject: Geotechnical Investigation Alexanders Landing Subdivision 4575 West Quarter Horse Lane Meridian, ID Dear Sabrina Durtschi: In compliance with your instructions, Atlas has conducted a soils exploration and foundation evaluation for the above referenced development. Fieldwork for this investigation was conducted on December 5, 2023. 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. Atlas would be pleased to continue our role as geotechnical engineers during project implementation. If you have any questions, please call us at (208) 376-4748. Respectfully submitted, Max Kasberger, PE Monica Saculles, PE Geotechnical Engineer Senior Geotechnical Engineer Clinton Wyllie, PG Staff Geologist Atlas No. B232086g Page i i Copyright©2023 Atlas Technical Consultants �TrT-G7T�1 CONTENTS 1. INTRODUCTION ...................................................................................................................2 1.1 Project Description........................................................................................................2 1.2 Scope of Investigation...................................................................................................2 2. SITE DESCRIPTION .............................................................................................................2 2.1 Regional Geology .........................................................................................................2 2.2 General Site Characteristics .........................................................................................3 3. SEISMIC SITE EVALUATION...............................................................................................3 3.1 Geoseismic Setting.......................................................................................................3 3.2 Seismic Design Parameter Values ...............................................................................4 4. SOILS EXPLORATION ........................................................................................................ 4.1 Exploration and Sampling Procedures..........................................................................4 4.2 Laboratory Testing Program .........................................................................................4 4.3 Soil and Sediment Profile..............................................................................................5 4.4 Volatile Organic Scan ...................................................................................................5 5. SITE HYDROLOGY......................................................................................................... 5.1 Groundwater.................................................................................................................5 5.2 Soil Infiltration Rates.....................................................................................................6 6. FOUNDATION AND SLAB DISCUSSION AND RECOMMENDATIONS.............................7 6.1 Foundation Loading Information ...................................................................................7 6.2 Foundation Design Recommendations.........................................................................7 6.3 Crawl Space Recommendations...................................................................................8 6.4 Floor, Patio, and Garage Slab-on-Grade......................................................................8 PAVEMENT DISCUSSION AND RECOMMENDATIONS .................................................. 7.1 Pavement Design Parameters......................................................................................9 7.2 Flexible Pavement Sections..........................................................................................9 7.3 Pavement Subgrade Preparation................................................................................10 7.4 Common Pavement Section Construction Issues.......................................................10 8. CONSTRUCTION CONSIDERATIONS ..............................................................................11 8.1 Earthwork....................................................................................................................11 8.2 Grading .......................................................................................................................11 8.3 Dry Weather................................................................................................................12 8.4 Wet Weather...............................................................................................................12 8.5 Soft Subgrade Soils ....................................................................................................12 8.6 Frozen Subgrade Soils ...............................................................................................13 8.7 Structural Fill...............................................................................................................13 8.8 Fill Placement and Compaction ..................................................................................13 8.9 Backfill of Walls...........................................................................................................15 Atlas No. B232086g Page I ii Copyright©2023 Atlas Technical Consultants �TrT-G7T�1 8.10 Excavations...............................................................................................................15 8.11 Groundwater Control.................................................................................................16 9. GENERAL COMMENTS .....................................................................................................16 10. REFERENCES ..................................................................................................................17 TABLES Table 1 — Seismic Design Values .................................................................................................4 Table 2 —Typical Soil Profiles.......................................................................................................5 Table 3 — Groundwater Data.........................................................................................................6 Table 4 — Generalized Soil Infiltration Rates.................................................................................6 Table5 — Soil Bearing Capacity....................................................................................................7 Table 6 — Gravel Equivalent Method Flexible Pavement Specifications..................................... 10 Table 7 — Fill Material Criteria..................................................................................................... 13 Table 8 — Fill Placement and Compaction Requirements........................................................... 14 APPENDICES Appendix I Warranty and Limiting Conditions Appendix II Vicinity Map Appendix III Site Map Appendix IV Geotechnical Investigation Test Pit Log Appendix V Geotechnical General Notes Appendix VI Important Information About This Geotechnical Engineering Report Atlas No. B232086g Page I iii Copyright©2023 Atlas Technical Consultants 1. INTRODUCTION This report presents results of a geotechnical investigation and analysis in support of data utilized in design of structures as defined in the 2018 International Building Code (IBC). 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. 1.1 Project Description The proposed development is in the City of Meridian, Ada County, ID, and occupies a portion of the NW'/4SW'/4 of Section 10, Township 3 North, Range 1 West, Boise Meridian. The site to be developed is approximately 9.8 acres. Site maps included in the Appendix show the project location. This project will consist of construction of a 55-lot residential subdivision, serviced by asphalt- paved public roads. The existing residence in the eastern portion of the site will remain. Retaining walls are not anticipated as part of the project. Drainage is expected to be directed to onsite infiltration facilities. These facilities are expected to consist of a series of seepage beds adjacent to the roads onsite. Atlas has not been informed of the proposed grading plan. 1.2 Scope of Investigation Our scope of work was completed in general accordance with our proposal dated and authorized on November 29, 2023. Said authorization is subject to terms, conditions, and limitations described in the Professional Services Contract entered into between KB Home Idaho, LLC and Atlas. Atlas' scope of services included the following: • Subsurface exploration via test pits. • Field and laboratory testing of materials encountered and collected. • Preparation of this report, which includes project description, site conditions, and our engineering analysis and evaluation for the project. • The scope of work did not include design recommendations specific to individual residences. 2. SITE DESCRIPTION 2.1 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 Atlas No. B232086g Page12 Copyright©2023 Atlas Technical Consultants �rrN+=0 A�1. 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 "Gravel of Sunrise Terrace" as mapped by Othberg and Stanford (1993). The Sunrise terrace is the third terrace above the modern Boise River in the eastern Boise Valley, composed of sandy pebble and cobble gravel, and is about 115 feet above river level. Quaternary faulting has probably truncated and tilted this terrace along with older surfaces. The surface of this deposit is mantled with 3-7 feet of loess containing a weakly to moderately developed duripan. Based on stratigraphic correlation the Sunrise terrace may be correlative with the Wilder terrace further to the west. 2.2 General Site Characteristics The following details regarding site conditions are based on visual observations and review of available geologic and topographic maps and imagery: • Current Site Conditions: The site is approximately 9.8 acres. A two-story residential structure is present in the eastern portion of the site. The site is bisected by Quarter Horse Lane which runs east to west through the central portion of the site. Purdum Gulch Drain is present along the southwest corner of the site. • Vegetation: Vegetation on the site consists primarily of landscape trees, shrubs, and grasses adjacent to the structure. Mature trees are present in the northwest portion of the site and near the residential structure. • Topography: The site is relatively flat and level. • Drainage: 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 drainage from off-site sources. 3. SEISMIC SITE EVALUATION 3.1 Geoseismic Setting Soils on site are classed as Site Class D in accordance with Chapter 20 of the American Society of Civil Engineers (ASCE) publication ASCE/SEI 7-16. Structures constructed on this site should be designed per IBC requirements for such a seismic classification. Our investigation revealed low hazard potential resulting from potential earthquake motions including: slope instability, liquefaction, and surface rupture caused by faulting or lateral spreading. Atlas No. B232086g Page13 Copyright©2023 Atlas Technical Consultants 3.2 Seismic Design Parameter Values The ASCE 7-16 seismic design parameter values have been provided below. Table 1 — Seismic Design Values Seismic Design Parameter Design Value Site Class D "Default' Site Modified Peak Ground 0.196 Acceleration, PGAM Ss 0.286 (g) S, 0.105 (g) Fa 1.571 F 2.391 SMs 0.450 SM, 0.250 Sos 0.300 So, 0.167 4. SOILS EXPLORATION 4.1 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 pit sites were located in the field by means of a Global Positioning System (GPS) device 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. Samples obtained have been visually classified in the field, 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. Atlas recommends that these logs not be used to estimate fill material quantities. 4.2 Laboratory Testing Program Along with our field investigation, a supplemental laboratory testing program was conducted to determine additional pertinent engineering characteristics of subsurface materials. Laboratory tests were conducted in accordance with current specifications. The laboratory testing program for this report included: • Atterberg Limits Testing —ASTM D4318 • Grain Size Analysis —ASTM C117/C136 Atlas No. B232086g Page14 Copyright©2023 Atlas Technical Consultants �TrT-G7T�1 4.3 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. Table 2 —Typical Soil Profiles Soil Hori Approximate[ . il A I Density Surficial Soils' 0.0 to 4 feet Lean Clay, Sandy Lean Clay Very Stiff to Hard Intermediate 1 to 11.5 feet Sandy Silt, Clayey Sand, Silty Sand Hard/Medium Dense Soils to Dense s Sandy Silt, Clayey Gravel with Sand, Very Stiff to Hard/ Deeper Soils 3.5 to 15 feet Poorly Graded Sand with Silt Medium Dense to Very Dense 'Plowzones noted in portions of these horizons. 2Calcium carbonate cementation was noted within portions of these horizons. During excavation, sloughing of test pit sidewalls was observed. 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. 4.4 Volatile Organic Scan 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 apparent odors or discoloration typically associated with this type of contamination. Groundwater encountered did not exhibit obvious signs of contamination. 5. 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. 5.1 Groundwater During this field investigation, groundwater was encountered in test pits 4 and 5 at a depth of 14.0 feet bgs. No groundwater was present in the remaining test pits advanced to depths as great as 14.8 feet bgs. Atlas has previously performed 6 geotechnical investigations within 0.50 mile of the project site. Information from these investigations has been provided in the table below. Atlas No. B232086g Page15 Copyright©2023 Atlas Technical Consultants �TrT-G7Tdr-W� Table 3— Groundwater Data Approximate X from Site (mile) Direction from Site eet . . November 2019 0.00 Onsite 13.9 to 14.4 February 2005 0.04 West 8.4 to 11.2 August 2021 0.07 South 4.5 to 6.1 February 2018 0.07 South 5.6 to 7.0 December 2018 0.16 South 6.2 to 8.6 February 2022 0.24 South 7.6 to 10.5 Furthermore, Atlas conducted groundwater monitoring on a site approximately 0.24-mile to the south from February 2022 to July 2023. During this time groundwater fluctuations of approximately 1.5 feet were encountered between December and the high water level in September. Based on evidence of this investigation and background knowledge of the area, Atlas has determined that the typical seasonal high groundwater should remain greater than approximately 11 feet bgs. This depth can be confirmed through long-term groundwater monitoring. If desired, Atlas is available to perform this monitoring from piezometers installed in test pits 1,2,4 and 6. 5.2 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. Typical infiltration rates comprising the generalized soil profile for this study have been provided in the table below. Table 4— Generalized Soil Infiltration Rates Rate qP (inches Typical Infiltration Lean <2 Sandy Lean Clay Sandy Silt',2 2 to 4 Clayey Sand <2 to 6 Clayey Gravel with Sande Silty Sand' 4 to 8 Poorly Graded Sand with Silt2,3 6 to 10 *The presence of cementation may reduce infiltration rates to near zero. **Infiltration into and/or within close proximity to groundwater may reduce infiltration rates to near zero. ***Minor clay content may reduce infiltration rates. Atlas No. B232086g Page16 Copyright©2023 Atlas Technical Consultants �/��M" ■ �TrT-G tv_ 1. Due to the variability of soil types encountered, Atlas recommends that infiltration testing be conducted once the infiltration facility locations have been determined. However, for preliminary design purposes, an infiltration rate of 1 inch per hour can be assumed for the sandy silt, clayey sand, clayey gravel with sand, and poorly graded sand with silt soils. 6. FOUNDATION AND SLAB DISCUSSION AND RECOMMENDATIONS Various foundation types have been considered for support of the proposed structures. Two requirements must be met in the design of foundations. First, the applied bearing stress must be less than the ultimate bearing capacity of foundation soils to maintain stability. Second, total and differential settlement must not exceed an amount that will produce an adverse behavior of the superstructure. Allowable settlement is usually exceeded before bearing capacity considerations become important; thus, allowable bearing pressure is normally controlled by settlement considerations. 6.1 Foundation Loading Information Loads of up to 4,000 pounds per lineal foot for wall footings, and column loads of up to 50,000 pounds were assumed for settlement calculations. Total settlement should be limited to approximately 1 inch and differential settlement should be limited to approximately '/2 inch, provided the following design and construction recommendations are observed. 6.2 Foundation Design Recommendations Considering subsurface conditions and the proposed construction, it is recommended that the structure be founded upon conventional spread footings and continuous wall footings. The following recommendations are not specific to the individual structures, but rather should be viewed as guidelines for the subdivision-wide development. Based on data obtained from the site and test results from various laboratory tests performed, Atlas recommends the following guidelines for the net allowable soil bearing capacity: Table 5— Soil Bearing Capacity FootingDepth ■ . . . . . . . . .. Footings must bear on competent, undisturbed, 1,500 Ibs/ftz native lean clay soils, sandy lean clay soils, sandy silt soils, clayey sand sediments, or compacted Not Required for Native A'/3 increase is allowable granular structural fill. Existing plow zones, Soil if the alternative basic organics, and fill materials (if encountered) must be load combinations of completely removed from below foundation 95% for Granular Section 1605.3.2 of the elements.' Excavation depths ranging from roughly Structural Fill 2018 IBC are used in 0.7 to 1.0 foot bgs should be anticipated to expose proper bearing soils.2 design. 'It will be required for Atlas personnel to verify the bearing soil suitability for each structure 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 may be required. Atlas No. 13232086g Page17 Copyright©2023 Atlas Technical Consultants �r'Irr-c��1 The following sliding frictional coefficient values should be used: 1) 0.35 for footings bearing on native lean clay, sandy lean clay, sandy silt, and clayey sand soils and 2) 0.45 for footings bearing on granular structural fill. A passive lateral earth pressures of 256 pounds per square foot per foot (psf/ft) should be used for lean clay soils, 294 psf/ft should be used for sandy lean clay soils, 349 pounds per square foot per foot (psf/ft) should be used for sandy silt soils, and 370 psf/ft should be used for clayey sand sediments. For granular structural fill, a passive lateral earth pressure of 496 psf/ft should be used. Footings should be proportioned to meet either the stated soil bearing capacity or the 2018 IBC minimum requirements. Unsuitable soil types encountered at the bottom of footing excavations should be removed and replaced with granular structural fill. Excessively loose or soft areas that are encountered in the footings subgrade will require over-excavation and backfilling with granular structural fill. To minimize the effects of slight differential movement that may occur because of variations in the character of supporting soils and seasonal moisture content, Atlas recommends continuous footings be suitably reinforced to make them as rigid as possible. For frost protection, the bottom of external footings should be 24 inches below finished grade. Foundations must be backfilled in accordance with the Backfill of Walls section. 6.3 Crawl Space Recommendations Residences constructed with crawl spaces should be designed in a manner that will inhibit water in the crawl spaces. Atlas recommends that roof drains carry stormwater at least 10 feet away from each residence. Grades should be at least 5 percent for a distance of 10 feet away from all residences. In addition, rain gutters should be placed around all sides of residences, and backfill around stem walls should be placed and compacted in a controlled manner. 6.4 Floor, Patio, and Garage Slab-on-Grad Plow zones with organic materials were encountered in portions of the site. Atlas recommends that the organic materials be removed. If plow zones remain after organic materials have been removed, the exposed subgrade must be compacted to at least 95 percent of the maximum dry density as determined by ASTM D1557. Atlas personnel must be present during excavation to identify these materials. Organic, loose, or obviously compressive materials must be removed prior to placement of concrete floors or floor-supporting fill. In addition, the remaining subgrade should be treated in accordance with guidelines presented in the Earthwork section. Areas of excessive yielding should be excavated and backfilled with granular structural fill or suitable structural fill. Fill used to increase the elevation of the floor slab should consist of granular structural fill and suitable structural fill meeting the requirements detailed in the Structural Fill section. Fill materials must be compacted to a minimum 95 percent of the maximum dry density as determined by ASTM D 1557. Atlas No. B232086g Page18 Copyright©2023 Atlas Technical Consultants A free-draining granular mat should be provided below slabs-on-grade to provide drainage and a uniform and stable bearing surface. This should be a minimum of 4 inches in thickness and compacted to at least 95 percent of the maximum dry density as determined by ASTM D1557. The mat must consist of aggregate base material as specified in the Structural Fill section. A moisture-retarder should be placed beneath floor slabs to minimize potential ground moisture effects on moisture-sensitive floor coverings. The moisture-retarder should be at least 15-mil in thickness and have a permeance of less than 0.01 US perms as determined by ASTM E96. Placement of the moisture-retarder will require special consideration with regard to effects on the slab-on-grade and should adhere to recommendations outlined in the ACI 302.1 R and ASTM E1745 publications. Upon request, Atlas can provide further consultation regarding installation. 7. PAVEMENT DISCUSSION AND RECOMMENDATIONS 7.1 Pavement Design Parameters Project specific traffic loading information has not been provided. Based on the character of the proposed construction, Atlas has used a traffic index of 6 for residential roadways. Atlas can provide a project specific pavement design upon request. During a previous exploration on site in November 2019, Atlas collected a sample of near-surface soils for Resistance Value (R-value) testing representative of soils to depths of 1.5 feet below existing ground surface. This sample, consisting of sandy lean clay, yielded an R-value of less than 5. Atlas used an R-value of 4 in design. Atlas recommends a routine maintenance program that includes crack sealing on a regular basis and possible seal coating to extend the life span of the pavement section. 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. 7.2 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 section. ACHD parameters for traffic index and substitution ratios, which were obtained from the ACHD Policy Manual, were also used in the design. Atlas 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. Atlas No. B232086g Page19 Copyright©2023 Atlas Technical Consultants �TrT-G7Tdr-W� Table 6— Gravel Equivalent Method Flexible Pavement Specifications ComponentPavement Section Asphaltic Concrete 2.5 Inches Aggregate Base 4.0 Inches Structural Subbase 14.0 Inches Compacted Subgrade' See Pavement Subgrade Preparation Section 'It will be required for Atlas personnel to verify subgrade competency at the time of construction. Asphaltic Concrete: Asphalt mix design shall meet the requirements of ISPWC Section 810. Materials shall be placed in accordance with ISPWC Standard Specifications for Highway Construction. Aggregate Base: Material complying with ISPWC Standards for Type 1 Crushed Aggregate Materials. Structural Subbase: Material complying with ISPWC Section 801 for 3-inch or 6-inch Uncrushed Aggregate Materials. The maximum material diameter cannot exceed 2/3 the component thickness. 7.3 Pavement Subgrade Preparation Plow zones with organic materials were encountered in portions of the site. Atlas recommends that the organic materials be removed. If plow zones remain after organic materials have been removed, the exposed subgrade must be compacted to at least 95 percent of the maximum dry density as determined by ASTM D698 for flexible pavements and ASTM D1557 for rigid pavements. Atlas personnel must be present during excavation to identify these materials. t.,+ 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 Atlas 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. Atlas anticipated that pavement areas will be subjected to moderate traffic. Subgrade clayey and silty soils near and above optimum moisture contents may pump during compaction. Pumping or soft areas must be removed and replaced with granular structural fill. Atlas No. 13232086g Page110 Copyright©2023 Atlas Technical Consultants Fill material and aggregates, as well as compacted native subgrade soils, 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. 8. CONSTRUCTION CONSIDERATIONS 8.1 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. Mature trees and thick grasses 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/2 foot(minimum), and wasted or stockpiled for later use. However, in areas where trees are/were present, deeper excavation depths should be anticipated. Stripping depths should be adjusted in the field to assure that the entire root zone or disturbed zone or topsoil are removed prior to placement and compaction of fill materials. Exact removal depths should be determined during grading operations by Atlas 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 fill materials as defined in the Structural Fill section. Atlas 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. 8.2 Grading Positive grades must be maintained surrounding structures and pavements, including exterior slabs. The interface of plant bedding materials and underlying soils should be graded to provide drainage away from site elements. Otherwise, bedding materials may direct water to underlying fine-grained soils, which increases the potential for localized heave. Excessive watering of landscaping should be avoided. Atlas No. B232086g PageJ11 Copyright©2023 Atlas Technical Consultants 8.3 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 soils and fill materials 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. 8.4 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 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. 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 1'/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. Atlas is available to provide recommendations and guidelines at your request. Atlas No. B232086g Page112 Copyright©2023 Atlas Technical Consultants �TrT-G7T_�. 8.6 Frozen Subgrade Soils Prior to placement of 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 fill. The onsite, shallow clayey and silty 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 granular 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 granular structural fill, can also be used to mitigate the potential for frost heave. Atlas is available to provide further guidance/assistance upon request. 8.7 Structural Fill The following table defines the types of fill material that is suitable for use on the project. Refer to the Fill Placement and Compaction section for recommended placement locations for each fill type listed below. Table 7 — Fill Material Criteria Fill Type Material Lift Thickness* ISPWC Section 801 for 1-inch, 3-inch, or 6- Granular Structural Fill inch Uncrushed Aggregate and 12 inches ISPWC Section 802 Aggregate Base Aggregate Base ISPWC Section 802 for Type 1 Crushed 12 inches Aggregate Base Structural Subbase ISPWC Section 801 for 3-inch or 6-inch 12 inches Uncrushed Aggregate Suitable Structural Fill** Onsite/imported ML, SM, and GM soils that 6 inches are free of organics and debris Initial loose thickness,prior to compaction. **Onsite CL soils are unsuitable for use as fill material. 8.8 Fill Placement and Compaction Requirements for fill material type and compaction effort are dependent on the planned use of the material. The following table specifies material type and compaction requirements based on the placement location of the fill material. Atlas No. B232086g Page113 Copyright©2023 Atlas Technical Consultants �TrT-G7T_�. Table 8 — Fill Placement and Compaction Requirements Compactio Foundations Granular Structural Fill 95% of ASTM D1557 Interior Slab-on-Grade and Below Granular Structural Fill or 95% of ASTM D1557 Rigid Pavement Subgrade Suitable Structural Fill Top 4 Inches of Interior and Exterior Aggregate Base Material 95% of ASTM D1557 Slab-on-Grade Below Flexible Pavement Subgrade Granular Structural Fill or 95% of ASTM D698 or and Exterior Flatwork Areas Suitable Structural Fill 92% of ASTM D1557 Foundation and Retaining Wall Granular Structural Fill or 95% of ASTM D1557 Backfill* Suitable Structural Fill Utility Trench Backfill Granular Structural Fill or Per ISPWC Section 306 Suitable Structural Fill *Retaining wall backfill material cannot exceed a maximum particle size of 4-inches. Prior to placement of fill materials, surfaces must be prepared as outlined in the Earthwork section. Fill material must be placed in horizontal lifts not exceeding 6-inches in thickness for fine-grained soils and 12-inches in thickness for granular structural fill, aggregate base material, and subbase material. All fill material must be moisture-conditioned to achieve optimum moisture content prior to compaction. During placement all fill materials must be monitored and tested to confirm compaction requirements have been achieved, as specified above, prior to placement of subsequent lifts. In addition, compacted surfaces must be in a firm and unyielding condition. Atlas personnel should be onsite to verify suitability of subgrade soil conditions, identify whether further work is necessary, and perform in-place moisture density testing. Sufficient density tests should be performed to properly monitor compaction. At a minimum, Atlas recommends one test per lift as follows: • Structures— 1 test every 5,000 square feet • Pavement and Exterior Flatwork Areas — 1 test every 10,000 square feet • Foundation and Retaining Wall Backfill — 1 test every 500 square feet • Utility Trench Backfill — 1 test every 100 linear feet Silty soils require very high moisture contents for compaction, 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 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, the exposed surface must be protected from degradation resulting from construction traffic or subsequent construction. It is anticipated that fine-grained soils will not be suitable for reuse during the wet season. Atlas No. B232086g Page i 14 Copyright©2023 Atlas Technical Consultants Use of silty soils (GM, SM, and ML) as structural fill below footings is prohibited. For structural fill below footings, areas of compacted backfill must extend outside the perimeter of the footings for a distance equal to the thickness of fill between the bottom of foundation and underlying soils, or 5 feet, whichever is less. If material contains more than 40 percent but less than 50 percent oversize (greater than %-inch) particles, compaction of fill must be confirmed per ISPWC Section 202.3.8.C.3. Material should contain sufficient fines to fill void spaces and must not contain more than 50 percent oversize particles. 8.9 Backfill of Walls Backfill materials must conform to the requirements of structural fill, as defined in this report. For wall heights greater than 2.5 feet, the maximum material size should not exceed 4 inches in diameter. Placing oversized material against rigid surfaces interferes with proper compaction and can induce excessive point loads on walls. Backfill shall not commence until the wall has gained sufficient strength to resist placement and compaction forces. Further, retaining walls above 2.5 feet in height shall be backfilled in a manner that will limit the potential for damage from compaction methods and/or equipment. It is recommended that only small hand-operated compaction equipment be used for compaction of backfill within a horizontal distance equal to the height of the wall, measured from the back face of the wall. Backfill should be compacted in accordance with the specifications in the Fill Placement and Compaction section, except in those areas where it is determined that future settlement is not a concern, such as planter areas. In nonstructural areas, backfill must be compacted to a firm and unyielding condition. Atlas recommends in these areas that the top 12 inches must consist of a low permeability (clay or silt) soil to limit surface water infiltration. Proper grading away from structures is critical. The surface must be graded away from the structure. In addition, Atlas recommends that roof drains carry stormwater at least 10 feet away from the structure. 8.10 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 (11/2:1) 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. Atlas No. B232086g Page115 Copyright©2023 Atlas Technical Consultants During the subsurface exploration,test pit sidewalls generally exhibited little indication of collapse; however, sloughing of 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. 8.11 Groundwater Control Groundwater was encountered during the investigation but is anticipated to be below the depth of most construction. Excavations below the water table will require a dewatering program. Dewatering will be required prior to placement of fill materials. Placement of concrete can be accomplished through water using a tremie. It may be possible to discharge dewatering effluent to remote portions of the site, to a sump, or to a pit. This will essentially recycle effluent, thus eliminating the need to enter into agreements with local drainage authorities. Should the scope of the proposed project change, Atlas should be contacted to provide more detailed groundwater control measures. 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. 9. GENERAL COMMENTS Based on the subsurface conditions encountered during this investigation and available information regarding the proposed development, the site is adequate for the planned construction. When plans and specifications are complete, and if significant changes are made in the character or location of the proposed development, consultation with Atlas must be arranged as supplementary recommendations may be required. Suitability of subgrade soils and compaction of fill materials must be verified by Atlas personnel prior to placement of structural elements. Additionally, monitoring and testing should be performed to verify that suitable materials are used for fill and that proper placement and compaction techniques are utilized. Atlas No. B232086g Page116 Copyright©2023 Atlas Technical Consultants 10. REFERENCES American Concrete Institute (ACI) (2015). Guide for Concrete Floor and Slab Construction: ACI 302.1 R. Farmington Hills, MI: ACI. American Society of Civil Engineers (2021). ASCE 7 Hazards Tool: Web Interface. [Online] Available: <https:Hasce7hazardtool.online/> (2023). American Society of Civil Engineers (ASCE) (2017). Minimum Design Loads for Buildings and Other Structures: ASCE/SEI 7-16. Reston, VA: ASCE. American Society for Testing and Materials (ASTM) (2017). Standard Test Method for Materials Finer than 75-um (No. 200) Sieve in Mineral Aggregates by Washing: ASTM C117. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2019). Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates: ASTM C136. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2021). 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) (2021). 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) (2018). 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)(2017). 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)(2017). Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils: ASTM D4318. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2017). Standard Specification for Plastic Water Vapor Retarders Used in Contact with Soil or Granular Fill Under Concrete Slabs: ASTM E1745. West Conshohocken, PA: ASTM. Idaho Transportation Department (ITD) (2019). Idaho Transportation Department Materials Manual, 2020. Boise, ID: Author. International Building Code Council (2018). International Building Code. Country Club Hills, IL: Author. Local Highway Technical Assistance Council (LHTAC) (2020). Idaho Standards for Public Works Construction. Boise, ID: Author. Othberg, K. L. and Stanford, L. A., Idaho Geologic Society (1993). Geologic Map of the Boise Valley and Adjoining Area, Western Snake River Plain, Idaho. (scale 1:100,000). Boise, ID: Joslyn and Morris. U.S. Department of Labor, Occupational Safety and Health Administration 2020 . CFR 29, Part 1926, Subpart P Appendix A: Safety and Health Regulations for Construction, Excavations. Washington D.C.: OSHA. Atlas No. B232086g Page117 Copyright©2023 Atlas Technical Consultants APPENDIX I WARRANTY AND LIMITING CONDITIONS Atlas 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 Atlas Technical Consultants ("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 nor 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 Subject 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, Atlas 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 Atlas should be retained to observe actual subsurface conditions during earthwork construction activities to provide additional construction recommendations as needed. Atlas No. B232086g Page118 Copyright©2023 Atlas Technical Consultants 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. This report is also limited to information available at the time it was prepared. In the event additional information is provided to Atlas 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 II/III Environmental Site Assessment. If environmental services are needed, Atlas can provide, via a separate contract, those personnel who are trained to investigate and delineate soil and water contamination. Atlas No. B232086g Page119 Copyright©2023 Atlas Technical Consultants Vicinity Map Figure 1 y ' on Lake S, ram rM Fieldstream Dr w Clair&N �a,,,. a� MAP NOTES: _ z w.am x N® •Not to Scale _ w r�er St � cry D W�urtfe. h� W4Jarboraoim,0 R a 4' ➢ C `, 7s z Ln WCLmw Dr 2 W MUHt`e'dDr z � w Charles Sp c W Ravenscio` mCherry Lane Golf Course �, w7d+Dr WJanAkeeSi1 x Rwo Tana D z S S a Linder LEGEND rod vd scan W pawson ur a, 'T+yt� rt 2m N x z Elementary Safford.5u61ateral Y z .Sa„0 5c"°°' Approximate Site IV Ca 4'aite qsh r� rx swrey Location 1�fi 1ry� z. . wFigansr A v� N°' n WMcGIInchr/St 3 i z s wannst � I N Cherry Ln W[t,.rry ir.-Settlers Canal W cFw"to FI W Cherry Ln b ITS = tl 5 - W 7ham Creek Sr W Leonard St -- — .._Tc+rrrtile Creek— W81ae Cseak pT w Aark �.Z W sheryl St soma or.�d x W w1w rd St ¢ I.I. P.f ape or P W Elm PI w Dig:reeh 5t W 6t$ m °Ck y Lateral _ Chaparral N ! a Dr W=iUette St Fuller Park Elementary re zWForast 5t cheel WWare Dry Meridi an High "r WCar]mn St Sch°ci 0 W Dover or W State St W State m I z zar5r 4r g W H¢arsi D' 414 St W Pirw Are W Pine Ave � aF2 WJaytcn Dr a E z z it tg � N — x 1y h W Pine In Purdam Gul-ch drain z W N:wland 5[ � 'yy k'Sryrrer g�F' o. a `� K� v `8 p G� p � Se Location v ul ziul3 W-Franklin Rd— z. W Franklin Rd W Franklii Rd z Alexanders Landing Subdivision m 4575 West Quarter Horse Lane 9 Tenmire Creek _W�reenheadw Meridian,ID S m R°senle% ""epf,�Rral Modified by:MPK y'rrnrall E December 7,2023 Kennedy Lateral Drawing:B232086g Waltman St mom I IL 2791 S.Victory View Way Phone: (208)376-4748 arr Boise,ID 83709 Fax: (208)322-6515 a �r 9 71 Web: oneatlas.com Site Map Figure 2 NOTES: PINE AVENUE N •Not to Scale 0 •,. # LEGEND � Approximate roximate Site Boundary Approximate Atlas Test �--�' - Pit Location lb # Approximate Atlas Test i I TP 2 Pit Location �. - with Piezometer 0 QUARTER HORSE LANE Q Y r — U Q J m s• TP-4 .r r• 14r TP-6 Alexanders Landing Subdivision -` 4575 West Quarter Horse Lane r - Meridian,ID - 8 Modified by:MPK r December 7,2023 ADrawing:B232086g PURDAM GULCH •f - t AL 2791 S.Victory View Way Phone: (208)376-4748 Boise,ID 83709 Fax: (208)322-6515 0 1 1 Web: oneatlas.com �TrT-G7T�1 APPENDIX IV GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-1 Latitude: 43.611905 Date Advanced: December 5, 2023 Longitude: -116.456147 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Wyatt Wolfe, El Total Depth: 13.9 feet bgs Depth Field Description and USCS Soil and Sample Sample De7p Lab ,IF 11 • • •s) Sediment Classification • bgs) Test I Sandy Lean Clay(CL): Brown, slightly moist to moist, very stiff to hard, with fine to medium- 0.0-2.0 grained sand. 4.0-4.5+ --Organics noted to 0.3 foot bgs. --Plow zone noted to 0.9 foot bgs. 2.0-3.8 Lean Clay (CL): Brown, slightly moist, hard, GS 2.0-2.5 4.5+ A with fine-grained sand. Clayey Sand (SC): Brown to red-brown, dry, 3.8-7.2 medium dense to dense, with fine to coarse- grained sand. Poorly Graded Sand with Silt(SP-SM): Brown, 7.2-13.9 dry, dense, with fine to coarse-grained sand and trace fine gravel. Notes:See Site Map for test pit location. Piezometer installed to a depth of 13.9 feet bgs. Passing) • Test ID Moisture LL P1 Sieve Analysis (% 1 1 11 11 A 24.9 38 17 100 100 99 98 93.7 Atlas No. B232086g Page 122 Copyright©2023 Atlas Technical Consultants �TrT-G7T�-1 GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-2 Latitude: 43.611402 Date Advanced: December 5, 2023 Longitude: -116.452596 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Wyatt Wolfe, El Total Depth: 14.5 feet bgs 'epth ield Description and USCS Soil and Sample Sample Dept I 09b r(feet . . Iff bgs) lip Test ID Sandy Lean Clay (CL): Light brown to brown, 0.0-1.8 dry, hard, with fine-grained sand. 4 5+ --Organics noted to 0.4 foot bgs. --Plow zone noted to 0.7 foot bgs. 1.8-5.7 Sandy Silt (ML): Light brown, dry, hard, with 4 5+ fine-grained sand. Poorly Graded Sand with Silt (SP-SM): Brown 5.7-10.2 to red-brown, dry, medium dense, with fine to medium-grained sand. --Minor clay content noted throughout. 10.2-14.5 Sandy Silt (ML): Brown, dry to slightly moist, very stiff to hard, with fine-grained sand. Notes:See Site Map for test pit location. Piezometer installed to a depth of 14.5 feet bgs. Atlas No. B232086g Page 123 Copyright©2023 Atlas Technical Consultants �TrT-G7T�__1 GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-3 Latitude: 43.611638 Date Advanced: December 5, 2023 Longitude: -116.451989 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Wyatt Wolfe, El Total Depth: 9.8 feet bgs Depth ield Description and USCS Soil and Sample Sample Dept Lab • •sA) e Sediment Classification • bgs) IV Test ID Sandy Lean Clay (CL): Light brown to brown, 0.0-1.9 dry, hard, with fine-grained sand. 4 5+ --Organics noted to 0.3 foot bgs. --Plow zone noted to 1.0 foot bgs. 1.9-3.6 Sandy Silt (ML): Light brown, dry, hard, with 4 5+ fine-grained sand. Poorly Graded Sand with Silt(SP-SM): Brown, 3.6-9.8 dry, medium dense, with fine to medium- grained sand. --Refusal due to caving sands. Notes:See Site Map for test pit location. Atlas No. B232086g Page 124 Copyright©2023 Atlas Technical Consultants �TrT-G7T�__1 GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-4 Latitude: 43.610643 Date Advanced: December 5, 2023 Longitude: -116.452167 Excavated by: Turn of the Century Homes Depth to Water Table: 14.0 feet bgs Logged by: Wyatt Wolfe, El Total Depth: 14.7 feet bgs Depth ield Description and USCS Soil and Sample Sample Dept Lab • •sA) e Sediment Classification • bgs) IV Test ID Sandy Lean Clay (CL): Light brown to brown, 0.0-1.0 dry, hard, with fine-grained sand. 4 5+ --Organics noted to 0.3 foot bgs. --Plow zone noted to 1.0 foot bgs. Sandy Silt (ML): Light brown to brown, dry, 1.0-2.2 hard, with fine-grained sand. 4 5+ --Weak to moderate calcium carbonate cementation encountered throughout. Silty Sand (SM): Light brown to brown, dry, 2.2-6.8 medium dense, with fine to medium-grained sand. Poorly Graded Sand with Silt(SP-SM): Brown, 6.8-11.0 dry, medium dense, with fine to medium- grained sand. Clayey Gravel with Sand (GC): Dark brown to brown, slightly moist to saturated, dense to 11.0-14.7 very dense, with fine to coarse-grained sand, fine to coarse gravel, and 6-inch minus cobbles. Notes:See Site Map for test pit location. Piezometer installed to a depth of 14.7 feet bgs Atlas No. B232086g Page 125 Copyright©2023 Atlas Technical Consultants �TrT-G7T�__1 GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-5 Latitude: 43.610229 Date Advanced: December 5, 2023 Longitude: -116.452463 Excavated by: Turn of the Century Homes Depth to Water Table: 14.0 feet bgs Logged by: Wyatt Wolfe, El Total Depth: 14.3 feet bgs Depth ield Description and USCS Soil and Sample Sample Dept • •sA) e Sediment Classification • • • Sandy Lean Clay (CL): Light brown to brown, dry to slightly moist, hard, with fine-grained 0.0-0.8 sand. 4.5+ --Organics noted to 0.3 foot bgs. --Plow zone noted throughout. Sandy Silt (ML): Light brown to brown, dry to 0.8-5.4 slightly moist, hard, with fine-grained sand. 4.5+ Silty Sand (SM): Light brown to brown, dry, medium dense, with fine to medium-grained 5.4-9.8 sand. --Weak to moderate calcium carbonate cementation encountered from 7.5 to 9.4 feet bgs. Clayey Gravel with Sand (GC): Dark brown to brown, slightly moist to saturated, dense to 9.8-14.3 very dense, with fine to coarse-grained sand, fine to coarse gravel, and 6-inch minus cobbles. Notes:See Site Map for test pit location. Atlas No. B232086g Page 126 Copyright©2023 Atlas Technical Consultants �TrT-G7T�__1 GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-6 Latitude: 43.610386 Date Advanced: December 5, 2023 Longitude: -116.451607 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Wyatt Wolfe, El Total Depth: 14.8 feet bgs Depth ield Description and USCS Soil and Sample Sample Dept Lab • •sA) e Sediment Classification • bgs) IN Test ID Sandy Lean Clay (CL): Light brown to brown, dry to slightly moist, hard, with fine-grained 0.0-0.7 sand. 4.5+ --Organics noted to 0.3 foot bgs. --Plow zone noted to 0.7 foot bgs. Sandy Silt (ML): Light brown to brown, dry to 0.7-2.6 slightly moist, hard, with fine-grained sand. 4 5+ --Weak to moderate calcium carbonate cementation encountered throughout. Silty Sand (SM): Light brown to brown, dry, 2.6-7.2 medium dense to dense, with fine to medium- grained sand. 7.2-11.4 Sandy Silt(ML): Brown, slightly moist to moist, stiff to very stiff, with fine-grained sand. Clayey Gravel with Sand (GC): Dark brown to 11.4-14.8 brown, slightly moist, dense to very dense, with fine to coarse-grained sand,fine to coarse gravel, and 6-inch minus cobbles. Notes:See Site Map for test pit location. Piezometer installed to a depth of 14.8 feet bgs Atlas No. B232086g Page 127 Copyright©2023 Atlas Technical Consultants �TrT-G7Tdr-W1 APPENDIX V GEOTECHNICAL GENERAL NOTES Unified Soil Classification System Major Divisions Symbol Soil Descriptions Gravel & GW Well-graded ravels; ravel/sand mixtures with little or no fines Coarse- Gravelly Soils GP Poorly-graded ravels; ravel/sand mixtures with little or no fines Grained < 50% GM Silty gravels; poorly-graded ravel/sand/silt mixtures Soils < coarse GC Clayey ravels; poorly-graded raded gravel/sand/clay mixtures 50% Y Y 9 p Y-9 9 Y passes Sand & Sandy SW Well-graded sands; ravel) sands with little or no fines No.200 Soils > 50% SP Poorl - raded sands; ravel) sands with little or no fines sieve coarse SM Silt sands; poorly-graded sand/gravel/silt mixtures fraction SC Clayey sands; poorly-graded sand/gravel/clay mixtures Fine- ML Inorganic silts; sandy, gravelly or clayey silts Grained Silts & Clays CL Lean clays; inorganic, gravelly, sandy, or silty, low to medium- Soils > ILL < 50 plasticity clays 50% OL Organic, low-plasticity clays and silts passes MH Inorganic, elastic silts; sand ravel) or clayey elastic silts No.200 Silts & Clays CH Fat clays high-plasticity, inorganic clays sieve ILL > 50 OH Organic, medium to high-plasticity clays and silts Highly Organic Soils PT Peat, humus, hydric soils with high organic content Coarse-Grained Soils SPT Blow Counts N Description Field Test Very Loose: <4 Dry Absence of moisture, dry to touch Loose: 4-10 Slightly Moist Damp, but no visible moisture Medium Dense: 10-30 Moist Visible moisture Dense: 30-50 Wet Visible free water Very Dense: > 50 Saturated Soil is usually below water table Fine-Grained Soils SPT Blow Counts N Description Field Test Very Soft: <2 Weak Crumbles or breaks with handling or Soft: 2-4 slight finger pressure Medium Stiff: 4-8 Moderate Crumbles or breaks with Stiff: 8-15 considerable finger pressure Very Stiff: 15-30 Strong Will not crumble or break with finger Hard: > 30 pressure Boulders: > 12 in. GS grab ample Cobbles: 12 to 3 in. ILL Liquid Limit Gravel: 3 in. to 5 mm M moisture content Coarse-Grained Sand: 5 to 0.6 mm NP non-plastic Medium-Grained Sand: 0.6 to 0.2 mm PI Plasticity Index Fine-Grained Sand: 0.2 to 0.075 mm Qp penetrometer value, unconfined compressive Silts: 0.075 to 0.005 mm strength, tsf Clays: < 0.005 mm V vane value, ultimate shearing strength, tsf Atlas No. B232086g Page 128 Copyright©2023 Atlas Technical Consultants IMPOPIOnt InfOPM81100 Rhout ■ GeolechnicalmEngineeping Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help. The Geoprofessional Business Association (GBA) will not likely meet the needs of a civil-works constructor or even a has prepared this advisory to help you—assumedly different civil engineer.Because each geotechnical-engineering study a client representative—interpret and apply this is unique,each geotechnical-engineering report is unique,prepared geotechnical-engineering report as effectively as solely for the client. possible. In that way, you can benefit from a lowered Likewise,geotechnical-engineering services are performed for a specific exposure to problems associated with subsurface project and purpose.For example,it is unlikely that a geotechnical- conditions at project sites and development of engineering study for a refrigerated warehouse will be the same as them that,for decades, have been a principal cause one prepared for a parking garage;and a few borings drilled during of construction delays, cost overruns, claims, a preliminary study to evaluate site feasibility will not be adequate to and disputes. If you have questions or want more develop geotechnical design recommendations for the project. information about any of the issues discussed herein, contact your GBA-member geotechnical engineer. Do not rely on this report if your geotechnical engineer prepared it: Active engagement in GBA exposes geotechnical • for a different client; engineers to a wide array of risk-confrontation • for a different project or purpose; techniques that can be of genuine benefit for • for a different site(that may or may not include all or a portion of everyone involved with a construction project. the original site);or before important events occurred at the site or adjacent to it; e.g.,man-made events like construction or environmental Understand the Geotechnical-Engineering Services remediation,or natural events like floods,droughts,earthquakes, Provided for this Report or groundwater fluctuations. Geotechnical-engineering services typically include the planning, collection,interpretation,and analysis of exploratory data from Note,too,the reliability of a geotechnical-engineering report can widely spaced borings and/or test pits.Field data are combined be affected by the passage of time,because of factors like changed with results from laboratory tests of soil and rock samples obtained subsurface conditions;new or modified codes,standards,or from field exploration(if applicable),observations made during site regulations;or new techniques or tools.If you are the least bit uncertain reconnaissance,and historical information to form one or more models about the continued reliability of this report,contact your geotechnical of the expected subsurface conditions beneath the site.Local geology engineer before applying the recommendations in it.A minor amount and alterations of the site surface and subsurface by previous and of additional testing or analysis after the passage of time-if any is proposed construction are also important considerations.Geotechnical required at all-could prevent major problems. engineers apply their engineering training,experience,and judgment to adapt the requirements of the prospective project to the subsurface Read this Report in Full model(s). Estimates are made of the subsurface conditions that Costly problems have occurred because those relying on a geotechnical- will likely be exposed during construction as well as the expected engineering report did not read the report in its entirety.Do not rely on performance of foundations and other structures being planned and/or an executive summary.Do not read selective elements only.Read and affected by construction activities. refer to the report in full. The culmination of these geotechnical-engineering services is typically a You Need to Inform Your Geotechnical Engineer geotechnical-engineering report providing the data obtained,a discussion About Change of the subsurface model(s),the engineering and geologic engineering Your geotechnical engineer considered unique,project-specific factors assessments and analyses made,and the recommendations developed when developing the scope of study behind this report and developing to satisfy the given requirements of the project.These reports may be the confirmation-dependent recommendations the report conveys. titled investigations,explorations,studies,assessments,or evaluations. Typical changes that could erode the reliability of this report include Regardless of the title used,the geotechnical-engineering report is an those that affect: engineering interpretation of the subsurface conditions within the context - the site's size or shape; of the project and does not represent a close examination,systematic inquiry,or thorough investigation of all site and subsurface conditions. the elevation,configuration,location,orientation, function or weight of the proposed structure and Geotechnical-Engineering Services are Performed the desired performance criteria; the composition of the design team;or for Specific Purposes, Persons, and Projects, . project ownership. and At Specific Times Geotechnical engineers structure their services to meet the specific As a general rule,always inform your geotechnical engineer of project needs,goals,and risk management preferences of their clients.A or site changes-even minor ones-and request an assessment of their geotechnical-engineering study conducted for a given civil engineer impact.The geotechnical engineer who prepared this report cannot accept responsibility or liability for problems that arise because the geotechnical conspicuously that you've included the material for information purposes engineer was not informed about developments the engineer otherwise only.To avoid misunderstanding,you may also want to note that would have considered. "informational purposes"means constructors have no right to rely on the interpretations,opinions,conclusions,or recommendations in the Most Of the "Findings" Related in This Report report.Be certain that constructors know they may learn about specific Are Professional Opinions project requirements,including options selected from the report,only Before construction begins,geotechnical engineers explore a site's from the design drawings and specifications.Remind constructors subsurface using various sampling and testing procedures.Geotechnical that they may perform their own studies if they want to,and be sure to engineers can observe actual subsurface conditions only at those specific allow enough time to permit them to do so.Only then might you be in locations where sampling and testing is performed.The data derived from a position to give constructors the information available to you,while that sampling and testing were reviewed by your geotechnical engineer, requiring them to at least share some of the financial responsibilities who then applied professional judgement to form opinions about stemming from unanticipated conditions.Conducting prebid and subsurface conditions throughout the site.Actual sitewide-subsurface preconstruction conferences can also be valuable in this respect. conditions may differ-maybe significantly-from those indicated in this report.Confront that risk by retaining your geotechnical engineer Read Responsibility Provisions Closely to serve on the design team through project completion to obtain Some client representatives,design professionals,and constructors do informed guidance quickly,whenever needed. not realize that geotechnical engineering is far less exact than other engineering disciplines.This happens in part because soil and rock on This Report's Recommendations Are project sites are typically heterogeneous and not manufactured materials Confirmation-Dependent with well-defined engineering properties like steel and concrete.That The recommendations included in this report-including any options or lack of understanding has nurtured unrealistic expectations that have alternatives-are confirmation-dependent.In other words,they are not resulted in disappointments,delays,cost overruns,claims,and disputes. final,because the geotechnical engineer who developed them relied heavily TO confront that risk,geotechnical engineers commonly include on judgement and opinion to do so.Your geotechnical engineer can finalize explanatory provisions in their reports.Sometimes labeled"limitations,' the recommendations only after observing actual subsurface conditions many of these provisions indicate where geotechnical engineers' exposed during construction.If through observation your geotechnical responsibilities begin and end,to help others recognize their own engineer confirms that the conditions assumed to exist actually do exist, responsibilities and risks.Read these provisions closely.Ask questions. the recommendations can be relied upon,assuming no other changes have Your geotechnical engineer should respond fully and frankly. occurred.The geotechnical engineer who prepared this report cannot assume responsibility or liabilityfor confirmation-dependent recommendations fyou Geoenvironmental Concerns Are Not Covered fail to retain that engineer to perform construction observation. The personnel,equipment,and techniques used to perform an environmental study-e.g.,a"phase-one"or"phase-two"enviromnental This Report Could Be Misinterpreted site assessment-differ significantly from those used to perform a Other design professionals'misinterpretation of geotechnical- geotechnical-engineering study.For that reason,a geotechnical-engineering engineering reports has resulted in costly problems.Confront that risk report does not usually provide environmental findings,conclusions,or by having your geotechnical engineer serve as a continuing member of recommendations;e.g.,about the likelihood of encountering underground the design team,to: storage tanks or regulated contaminants.Unanticipated subsurface • confer with other design-team members; environmental problems have led to project failures.If you have not • help develop specifications; obtained your own environmental information about the project site, review pertinent elements of other design professionals'plans and ask your geotechnical consultant for a recommendation on how to find specifications;and environmental risk-management guidance. • be available whenever geotechnical-engineering guidance is needed. Obtain Professional Assistance to Deal with You should also confront the risk of constructors misinterpreting this Moisture Infiltration and Mold report.Do so by retaining your geotechnical engineer to participate in While your geotechnical engineer may have addressed groundwater, prebid and preconstruction conferences and to perform construction- water infiltration,or similar issues in this report,the engineer's phase observations. services were not designed,conducted,or intended to prevent migration of moisture-including water vapor-from the soil Give Constructors a Complete Report and Guidance through building slabs and walls and into the building interior,where Some owners and design professionals mistakenly believe they can shift it can cause mold growth and material-performance deficiencies. unanticipated-subsurface-conditions liability to constructors by limiting Accordingly,proper implementation of the geotechnical engineer's the information they provide for bid preparation.To help prevent recommendations will not of itself be sufficient to prevent the costly,contentious problems this practice has caused,include the moisture infiltration.Confront the risk of moisture infiltration by complete geotechnical-engineering report,along with any attachments including building-envelope or mold specialists on the design team. or appendices,with your contract documents,but be certain to note Geotechnical engineers are not building-envelope or mold specialists. GEOPROFESSIONAL BUSINESS SEA ASSOCIATION Telephone:301/565-2733 e-mail:info@geoprofessional.org www.geoprofessional.org Copyright 2019 by Geoprofessional Business Association(GBA).Duplication,reproduction,or copying of this document,in whole or in part,by any means whatsoever,is strictly prohibited,except with GBAs specific written permission.Excerpting,quoting,or otherwise extracting wording from this document is permitted only with the express written permission of GBA,and only for purposes of scholarly research or book review.Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind. Any other firm,individual,or other entity that so uses this document without being a GBA member could be committing negligent or intentional(fraudulent)misrepresentation. s IC ENGINEERING P . C . Civil Engineering * Project Management GEOTECHNICAL REPORT ADDENDUM CK Engineering 13oo E.State St Suite 102 Eagle,ID 83616 208.869.0590 mobile chad@ck-engineers.com �/��M" ■ p �TrT-G7T-*1. February 27, 2024 Atlas No. B240237g Sabrina Durtschi KB Home Idaho, LLC 1414 West Bannock Street Boise, ID 83702 Subject: Addendum #1 — Infiltration Testing Horse Meadows 710 North Black Cat Road Meridian, ID Dear Sabrina Durtschi: This addendum report presents test results not requested at the time of the previously issued Atlas Geotechnical Engineering Report (B240237g). 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. INFILTRATION TESTING Infiltration testing was conducted using an open test pit method. The test location was presoaked prior to testing. Pre-soaking increases soil moistures, which allows the tested soils to reach a saturated condition more readily during testing. Saturation of the tested soils is desirable in order to isolate the vertical component of infiltration by inhibiting horizontal seepage during testing. On February 16, 2024, testing was conducted within poorly graded sand with silt sediments at a depth of 6.4 feet bgs in test pit 1. A stabilized infiltration rate of 2.4 inches per hour was achieved during testing. Atlas recommends a design infiltration rate of 1.2 inches per hour. The reason for the decreased infiltration rate is to account for long term saturation of the soils and the potential for less permeable soils to settle into the bottom of the infiltration facilities. Atlas recommends that all infiltration facilities be constructed in accordance with the local municipality requirements. Atlas No. B240237g Page11 Copyright©2024 Atlas Technical Consultants �rrN+=O A�1. If you have any questions, please call us at (208) 376-4748. Respectfully submitted, Max Kasberger, PE Jacob Schlador, PE Geotechnical Engineer Geotechnical Practice Manager- Northwest Attachments: Site Map Geotechnical Investigation Test Pit Log Geotechnical General Notes Atlas No. B240237g Page12 Copyright©2024 Atlas Technical Consultants Addendum Site Map Figure 1 NOTES: PINE AVENUE N •Not to Scale _ r LEGEND Approximate Site Boundary F Approximate Atlas Test Pit Location 8 5 ,i QUARTER HORSE LANE — U Q J _ m s• i :r r+' .r 14r Horse Meadows 710 North Black Cat Road r Meridian,ID Modified by:MPK February 21,2024 Drawing:B240237g A'. r - — PURDAM GULCH t �r'1r�rc-1r�� ITT 2791 S.Victory View Way Phone: (208)376-4748 Boise,ID 83709 Fax: (208)322-6515 0 1 1 Web: oneatlas.com �TrT-G7T�1 GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-1 Latitude: 43.611432 Date Advanced: February 15, 2024 Longitude: -116.452653 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Wyatt Wolfe, El Total Depth: 6.4 feet bgs Depth field Description and USCS Soil and Sample Sample Depth Lab Q• •• Jiment Classification • bgs) Test I Sandy Lean Clay (CL): Light brown to brown, 0.0-2.6 dry to slightly moist, stiff to very stiff, with fine to medium-grained sand. --Organics noted to 0.3 foot bgs. Sandy Silt (ML): Light brown, dry, very stiff, 2.6-5.0 with fine-grained sand. --Weak to moderate calcium carbonate cementation encountered throughout. Poorly Graded Sand with Silt (SP-SM): Brown 5.0-6.4 to red-brown, dry, medium dense, with fine to medium-grained sand. --Minor clay content noted throughout. Notes:See Site Map for test pit location. Infiltration testing conducted at a depth of 6.4 feet bgs. Atlas No. 13240237g Page14 Copyright©2024 Atlas Technical Consultants �TrT-G7Tdr-W1 GEOTECHNICAL GENERAL NOTES Major Divisions Symbol Soil Descriptions Gravel & GW Well-graded ravels; ravel/sand mixtures with little or no fines Coarse- Gravelly Soils GP Poorly-graded ravels; ravel/sand mixtures with little or no fines Grained < 50% GM Silty gravels; poorly-graded ravel/sand/silt mixtures Soils < coarse GC Clayey gravels; poorly-graded gravel/sand/clay mixtures 50% Sand & Sandy SW Well-graded sands; gravelly sands with little or no fines passes Soils > 50% SP Poorl - raded sands; gravelly sands with little or no fines No.200 coarse SM Silty sands; poorly-graded sand/gravel/silt mixtures sieve fraction SC Clayey sands; poorly-graded sand/gravel/clay mixtures Fine- ML Inorganic silts; sandy, gravellyor clayey silts Grained Silts & Clays CL Lean clays; inorganic, gravelly, sandy, or silty, low to medium- Soils > LL < 50 plasticity clays 50% OL Organic, low-plasticity clays and silts passes Silts & Clays MH Inorganic, elastic silts; sand ravel) or clayey elastic silts No.200 CH Fat clays; high-plasticity, inorganic clays sieve LL > 50 OH Or anic, medium to high-plasticity clays and silts Highly Organic Soils PT Peat, humus, h dric soils with high organic content ure Content and Cementation Classification Coarse-Grained Soils SPT Blow Counts N Description Field Test Very Loose: <4 Dr Absence of moisture, dryto touch Loose: 4-10 Slightly Moist Damp, but no visible moisture Medium Dense: 10-30 Moist Visible moisture Dense: 30-50 Wet Visible free water Very Dense: > 50 Saturated Soil is usually below water table Fine-Grained Soils SPT Blow Counts (N) Description Field Test Very Soft: < 2 Weak Crumbles or breaks with handling or Soft: 2-4 slight finger pressure Medium Stiff: 4-8 Moderate Crumbles or breaks with Stiff: 8-15 considerable finger pressure Very Stiff: 15-30 Strong Will not crumble or break with finger Hard: > 30 pressure Boulders: > 12 in. GSI_ L�grab sample Cobbles: 12 to 3 in. LLi uid Limit Gravel: 3 in. to 5 mm Mmoisture content Coarse-Grained Sand: 5 to 0.6 mm NP non-plastic Medium-Grained Sand: 0.6 to 0.2 mm PI Plasticity Index Fine-Grained Sand: 0.2 to 0.075 mm Qp penetrometer value, unconfined compressive Silts: 0.075 to 0.005 mm strength, tsf Clays: < 0.005 mm V vane value, ultimate shearing strength, tsf Atlas No. B240237g Page 15 Copyright©2024 Atlas Technical Consultants