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Storm Drainage Calcs V1 (2)
Prepared For: City of Meridian Hill’s Century Farm Commercial Subdivision #2 Meridian, Idaho Storm Drainage Report Prepared By: Mike Bultman, P.E. Project Engineer KM Engineering, LLP 9233 West State Street Boise, ID 83714 208.639.6939 mbultman@kmengllp.com October 8, 2021 Project No: 21-200 10/08/21 TABLE OF CONTENTS Introduction ................................................................................................................................. 1 Project Description ...................................................................................................................... 1 Site Description ............................................................................................................................... 1 Scope and Methods ...................................................................................................................... 1 Existing Drainage Conditions .......................................................................................................... 1 Proposed Drainage Conditions and Analysis .................................................................................. 1 Temporary Swales ........................................................................................................................... 1 ACHD Borrow Ditches ..................................................................................................................... 2 Summary ......................................................................................................................................... 2 APPENDICES Appendix A - Figures Post-Development Drainage Map Storm Water Improvement Plans Appendix B – Calculations Temporary Swales ACHD Borrow Ditches Appendix C - Geotechnical Engineering Report Geotechnical Engineering Report (Consultant) 1 INTRODUCTION The purpose of this report is to show that the storm drainage facilities for the proposed Hill’s Century Farm Commercial Subdivision #2 (Project) are designed to meet The City of Meridian, ACHD’s, and the Idaho Department of Environmental Quality (DEQ) water quality requirements. PROJECT DESCRIPTION The Project consists of the construction of a private commercial road throughout the Hill’s Century Commercial Subdivision and roadway improvements along the south side of E. Amity Rd. The proposed improvements include new roadways, sidewalks, storm drainage and site utilities. SITE DESCRIPTION The Project is located SE of the S. Tavistock Ave and E. Amity Road intersection in Meridian, ID. SCOPE AND METHODS The Rational Method is the standard method for small catchments and was used to calculate the post-development storm water volumes and flow rates for this project (see Appendix B - Calculations). EXISTING DRAINAGE CONDITIONS The pre-project watershed consists of undeveloped land that sheet flows from east to west untreated. The catch basins drain to temporary swales for vertical infiltration. Permanent storm drainage facilities will be constructed as the individual lots develop. PROPOSED DRAINAGE CONDITIONS AND ANALYSIS The proposed drainage system improvements consist of 2 temporary swales with sand windows along the private road and an ACHD borrow ditch along the south side of E. Amity Road. The post-development site was broken into eight (4) drainage basins found in Appendix A. Each basin was delineated according to the tributary area draining to each facility. TEMPORARY SWALES Based on our calculations, all temporary swales are adequately sized to ensure no ponding occurs on the asphalt surface and that storm water will infiltrate within the infiltration swale in a 24-hour period. The geotechnical report prepared by MTI dated October 11th , 2016 stated that ground water is anticipated to be deeper than an elevation of 2682.00. Once the size of the swale is calculated, the time necessary for infiltration of storm water into the ground is calculated at less than 23 hours. The geotechnical report measured an infiltration rate of greater than 12”/hr, and we used an infiltration rate of 8”/hour. 2 See Appendix B for further information. ACHD BORROW DITCHES Based on the attached ACHD spreadsheet, the two proposed borrow ditches along the south side of E. Amity Rd have been sized to meet the requirements. See Appendix B for further information. SUMMARY This report determines that the Project storm water design sizing and analysis conforms with the City of Meridian and ACHD storm water design criteria. APPENDIX A - FIGURES APPENDIX B - CALCULATIONS APPENDIX C - GEOTECHNICAL ENGINEERING REPORT TABLE OF CONTENTS Introduction ................................................................................................................................. 1 Project Description ...................................................................................................................... 1 Site Description ............................................................................................................................... 1 Scope and Methods ...................................................................................................................... 1 Existing Drainage Conditions .......................................................................................................... 1 Proposed Drainage Conditions and Analysis .................................................................................. 1 Temporary Swales ........................................................................................................................... 1 ACHD Borrow Ditches ..................................................................................................................... 2 Summary ......................................................................................................................................... 2 APPENDICES Appendix A - Figures Post-Development Drainage Map Storm Water Improvement Plans Appendix B – Calculations Temporary Swales ACHD Borrow Ditches Appendix C - Geotechnical Engineering Report Geotechnical Engineering Report (Consultant) 1 INTRODUCTION The purpose of this report is to show that the storm drainage facilities for the proposed Hill’s Century Farm Commercial Subdivision #2 (Project) are designed to meet The City of Meridian, ACHD’s, and the Idaho Department of Environmental Quality (DEQ) water quality requirements. PROJECT DESCRIPTION The Project consists of the construction of a private commercial road throughout the Hill’s Century Commercial Subdivision and roadway improvements along the south side of E. Amity Rd. The proposed improvements include new roadways, sidewalks, storm drainage and site utilities. SITE DESCRIPTION The Project is located SE of the S. Tavistock Ave and E. Amity Road intersection in Meridian, ID. SCOPE AND METHODS The Rational Method is the standard method for small catchments and was used to calculate the post-development storm water volumes and flow rates for this project (see Appendix B - Calculations). EXISTING DRAINAGE CONDITIONS The pre-project watershed consists of undeveloped land that sheet flows from east to west untreated. The catch basins drain to temporary swales for vertical infiltration. Permanent storm drainage facilities will be constructed as the individual lots develop. PROPOSED DRAINAGE CONDITIONS AND ANALYSIS The proposed drainage system improvements consist of 2 temporary swales with sand windows along the private road and an ACHD borrow ditch along the south side of E. Amity Road. The post-development site was broken into eight (4) drainage basins found in Appendix A. Each basin was delineated according to the tributary area draining to each facility. TEMPORARY SWALES Based on our calculations, all temporary swales are adequately sized to ensure no ponding occurs on the asphalt surface and that storm water will infiltrate within the infiltration swale in a 24-hour period. The geotechnical report prepared by MTI dated October 11th , 2016 stated that ground water is anticipated to be deeper than an elevation of 2682.00. Once the size of the swale is calculated, the time necessary for infiltration of storm water into the ground is calculated at less than 23 hours. The geotechnical report measured an infiltration rate of greater than 12”/hr, and we used an infiltration rate of 8”/hour. 2 See Appendix B for further information. ACHD BORROW DITCHES Based on the attached ACHD spreadsheet, the two proposed borrow ditches along the south side of E. Amity Rd have been sized to meet the requirements. See Appendix B for further information. SUMMARY This report determines that the Project storm water design sizing and analysis conforms with the City of Meridian and ACHD storm water design criteria. APPENDIX A - FIGURES PARCEL A PARCEL D PARCEL A PARCEL D M FINISHED FLOOR EL: 2694.22 S. TAVISTOCK AVE. LOT 11 LOT 13 LOT 12 LOT 14 BLOCK 2 E AMITY RD PARCEL A PARCEL D PARCEL A PARCEL D M FINISHED FLOOR EL: 2694.22 S. TAVISTOCK AVE. LOT 11 LOT 13 LOT 12 LOT 14 BLOCK 2 E AMITY RD M FINISHED FLOOR EL: 2694.22 PROJECT: DATE: NO. ITEM DATE REVISIONS SHEET NO. CHECKED BY: DRAWN BY: DESIGN BY: 5725 NORTH DISCOVERY WAY BOISE, IDAHO 83713 PHONE (208) 639-6939 kmengllp.com HILL'S CENTURY FARM COMMERCIAL SUBDIVISION #2 MERIDIAN, ID GRADING PLAN C4.0 21-200 10/08/21 TA MGB MGB P:\21-200\CAD\EXHIBITS\21-200 DRAINAGE MAP.DWG, MIKE BULTMAN, 10/8/2021, DWG TO PDF.PC3, ---- N * PROJECT: DATE: NO. ITEM DATE REVISIONS SHEET NO. CHECKED BY: DRAWN BY: DESIGN BY: 5725 NORTH DISCOVERY WAY BOISE, IDAHO 83713 PHONE (208) 639-6939 kmengllp.com HILL'S CENTURY FARM COMMERCIAL SUBDIVISION #2 MERIDIAN, ID PROJECT DETAILS C0.1 21-200 10/08/21 TA MGB MGB P:\21-200\CAD\CONSTRUCTION PLANS\21-200 C0.1 PROJECT DETAILS.DWG, MIKE BULTMAN, 10/8/2021, _DWG TO PDF.PC3, ---- ASPHALT PAVEMENT SECTION (PRIVATE ROAD) TYPICAL 2" SERVICE TEMPORARY DRAINAGE SWALE (PRIVATE) E. AMITY RD. SECTION S. TAVISTOCK AVE. LOT 11 LOT 13 LOT 12 LOT 14 BLOCK 2 E AMITY RD S. TAVISTOCK AVE. LOT 11 LOT 13 LOT 12 LOT 14 BLOCK 2 E AMITY RD PROJECT: DATE: NO. ITEM DATE REVISIONS SHEET NO. CHECKED BY: DRAWN BY: DESIGN BY: 5725 NORTH DISCOVERY WAY BOISE, IDAHO 83713 PHONE (208) 639-6939 kmengllp.com HILL'S CENTURY FARM COMMERCIAL SUBDIVISION #2 MERIDIAN, ID GRADING PLAN C4.0 21-200 10/08/21 TA MGB MGB P:\21-200\CAD\CONSTRUCTION PLANS\21-200 C4.0 GRADING PLAN.DWG, MIKE BULTMAN, 10/8/2021, _DWG TO PDF.PC3, ---- N GENERAL NOTES LEGEND SHEET NOTES KEY NOTES APPENDIX B - CALCULATIONS STORM DRAINAGE CALCULATIONS TRIB AREA: #1 Project No.: 21-200 Date: Project Description: Hill's Century Farm Commercial Subdivision #2 Swale: #1 Trib Area: #1 Runoff Event Frequency: 100 year METHOD: 1" STORM OVER IMPERVIOUS AREA Per City of Meridian standards: design storm event for the 100-year storm is for 1" of storm water over the entire tributary area 4,303 0 0 4,303 0.10 Item Coeff. Area S.F. Area AC. C tc T 1.5 tc Asphalt (S.F.) 0.95 4,303 0.10 0.95 Sidewalk (S.F.) 0.95 0 0.00 0.00 Landscape (S.F.) 0.15 0 0.00 0.00 Combined: 0.10 0.95 Triburaty Area 4303.0 ft 2 Intensity 1.0 in C 0.95 Volume to Retained= 340.7 ft 3 SWALE #: #1 Runoff Volume (per other calculations): 340.7 ft 3 Sediment Storage: 15.0 % Volume Required (VR): 391.8 ft 3 Depth 2.00 ft Average End Area: 204.0 ft 2 Swale Volume Provided: 408.0 ft 3 OK, VP > VR INFILTRATION: Infiltration Window per 100' Volume to be infiltrated: 340.7 ft 3 Infiltration Rate 8 in/hr Infiltration Width 6 ft Infiltration Length 11 ft First Hour Infiltration 44.0 ft 3 Time to infiltrate: 11.6 hr OK, < 24 hours TOTAL DRAINAGE AREA (S.F.) TOTAL DRAINAGE AREA (AC.) Vs = (T-tc)*Qp+(tc*Qp)/2+(1.5*tc*Qp)/2 - Vin Vin = (T+1.5*tc)*Qin/2 Modified Rational Method Hydrograph Landscape (S.F.) 10/7/2021 Drainage Area: Asphalt (S.F.) Sidewalk (S.F.) STORM DRAINAGE CALCULATIONS TRIB AREA: #2 Project No.: 21-200 Date: Project Description: Hill's Century Farm Commercial Subdivision #2 Swale: #2 Trib Area: #2 Runoff Event Frequency: 100 year METHOD: 1" STORM OVER IMPERVIOUS AREA Per City of Meridian standards: design storm event for the 100-year storm is for 1" of storm water over the entire tributary area 4,378 0 0 4,378 0.10 Item Coeff. Area S.F. Area AC. C tc T 1.5 tc Asphalt (S.F.) 0.95 4,378 0.10 0.95 Sidewalk (S.F.) 0.95 0 0.00 0.00 Landscape (S.F.) 0.15 0 0.00 0.00 Combined: 0.10 0.95 Triburaty Area 4378.0 ft 2 Intensity 1.0 in C 0.95 Volume to Retained= 346.6 ft 3 SWALE #: #2 Runoff Volume (per other calculations): 346.6 ft 3 Sediment Storage: 15.0 % Volume Required (VR): 398.6 ft 3 Depth 2.00 ft Average End Area: 204.0 ft 2 Swale Volume Provided: 408.0 ft 3 OK, VP > VR INFILTRATION: Infiltration Window per 100' Volume to be infiltrated: 346.6 ft 3 Infiltration Rate 8 in/hr Infiltration Width 6 ft Infiltration Length 11 ft First Hour Infiltration 44.0 ft 3 Time to infiltrate: 11.8 hr OK, < 24 hours Landscape (S.F.) 10/7/2021 Drainage Area: Asphalt (S.F.) Sidewalk (S.F.) TOTAL DRAINAGE AREA (S.F.) TOTAL DRAINAGE AREA (AC.) Vs = (T-tc)*Qp+(tc*Qp)/2+(1.5*tc*Qp)/2 - Vin Vin = (T+1.5*tc)*Qin/2 Modified Rational Method Hydrograph Steps for Peak Discharge Rate using the Rational Method calculated for post-development 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 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) 1 Click to Show More Subbasins Subbasin 1 Subbasin 2 Subbasin 3 Subbasin 4 Subbasin 5 Subbasin 6 Subbasin 7 Subbasin 8 Subbasin 9 Subbasin 10 5 Area of Drainage Subbasin (SF or Acres) SF 4,142 1,283 1,122 Acres 0.15 6 Determine the Weighted Runoff Coefficient (C) 0.95 0.70 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.77 7 I100, TC<=60 8 i 2.58 in/hr 9 Qpeak 0.30 cfs 10 V 401 ft 3 V = Ci (Tc=60)Ax3600 11 Enter Percentile Storm I (95th percentile = 0.60 in) 95th 0.60 in Enter Runoff Reduction Vol (95th Percentile=0.60-in x Area x C) Vrr 251 ft 3 12 Detention: Approved Discharge Rate to Surface Waters (if applicable) cfs 13 Volume Summary Surface Storage: Basin Basin Forebay V 40 ft 3 Primary Treatment/Storage Basin V 361 ft 3 Subsurface Storage Volume Without Sediment Factor (See BMP 20 Tab) V 401 ft 3 Determine the average rainfall intensity (i) from IDF Curve based on Tc Calculate the Post-Development peak discharge (QPeak) 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. Hill's Century Farm Commercial Subdivision #2 - ACHD Borrow Ditch #1 Calculate Overland Flow Time of Concentration in Minutes (Tc) or use default 10 min Calculate total runoff vol (V) (for sizing primary storage) Calculate Volume of Runoff Reduction Vrr Steps for Sizing Bioswale User input in yellow cells. 1 Project Name 2 2 Enter number of Bioswales/Borrow Ditches (25 max) 1 3 Design Storm 100 'Q,V' Weighted Runoff Coefficient C 0.77 Link to: 4 Area A (Acres) 0.15 acres Approved discharge rate for the given storm (if applicable) 0.00 cfs 5 Design Vol With 0% Sed for Swales V 401 ft3 6 Length of Swale 50 ft 7 Infiltration Window? (Note: infiltration required if Longitudinal Slope<1%) Design Infiltration Rate 8.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 14.00 ft 11 Set Swale Depth y 2.00 ft 12 Swale Side Slopes H:1 SXS 4.00 13 Calculate cross-sectional area AXS 20.00 14.00 ft2 AXS=y2z+by 14 Total Swale Capacity Without Driveways 700 ft3 15 Does it Have Capacity? OK 16 Time to Drain 6.0 hr 90% volume in 48-hours minimum OK Check Swale With Driveways 17 Avg. Driveway Fill Slope in Swale (H/V) ft/ft 18 Enter Total Number of Driveways ea 0.0 ft3 Deduct driveway slope 19 Enter Total Length of all Driveways ft 0.0 ft3 Deduct driveway length 20 Lost Swale Length From Trees, etc. ft 0.0 ft3 Deduct other 21 Adjusted Length of Infiltration Area 0.0 ft 22 Excess Capacity = Storage - Deductions - Runoff Volume (401.2) ft3 23 Is Capacity Good? NO 24 Time to Drain 0.0 hr 90% volume in 48-hours minimum OK 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. ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches Hill's Century Farm Commercial Subdivision #2 - ACHD Borrow Ditch #1 P:\21-200\Documents\Reports\Storm Drainage\21-200 ACHD Borrow Ditch #1 Version 10.0, May 2018 10/8/2021, 12:41 PM Steps for Peak Discharge Rate using the Rational Method calculated for post-development 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 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) 1 Click to Show More Subbasins Subbasin 1 Subbasin 2 Subbasin 3 Subbasin 4 Subbasin 5 Subbasin 6 Subbasin 7 Subbasin 8 Subbasin 9 Subbasin 10 5 Area of Drainage Subbasin (SF or Acres) SF 3,689 1,153 1,009 Acres 0.13 6 Determine the Weighted Runoff Coefficient (C) 0.95 0.70 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.77 7 I100, TC<=60 8 i 2.58 in/hr 9 Qpeak 0.27 cfs 10 V 358 ft 3 V = Ci (Tc=60)Ax3600 11 Enter Percentile Storm I (95th percentile = 0.60 in) 95th 0.60 in Enter Runoff Reduction Vol (95th Percentile=0.60-in x Area x C) Vrr 224 ft 3 12 Detention: Approved Discharge Rate to Surface Waters (if applicable) cfs 13 Volume Summary Surface Storage: Basin Basin Forebay V 36 ft 3 Primary Treatment/Storage Basin V 322 ft 3 Subsurface Storage Volume Without Sediment Factor (See BMP 20 Tab) V 358 ft 3 Calculate total runoff vol (V) (for sizing primary storage) Calculate Volume of Runoff Reduction Vrr Determine the average rainfall intensity (i) from IDF Curve based on Tc Calculate the Post-Development peak discharge (QPeak) 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. Hill's Century Farm Commercial Subdivision #2 - ACHD Borrow Ditch #2 Calculate Overland Flow Time of Concentration in Minutes (Tc) or use default 10 min Steps for Sizing Bioswale User input in yellow cells. 1 Project Name 2 2 Enter number of Bioswales/Borrow Ditches (25 max) 1 3 Design Storm 100 'Q,V' Weighted Runoff Coefficient C 0.77 Link to: 4 Area A (Acres) 0.13 acres Approved discharge rate for the given storm (if applicable) 0.00 cfs 5 Design Vol With 0% Sed for Swales V 358 ft 3 6 Length of Swale 47 ft 7 Infiltration Window? (Note: infiltration required if Longitudinal Slope<1%) Design Infiltration Rate 8.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 14.00 ft 11 Set Swale Depth y 2.00 ft 12 Swale Side Slopes H:1 SXS 4.00 13 Calculate cross-sectional area AXS 20.00 14.00 ft 2 AXS=y 2 z+by 14 Total Swale Capacity Without Driveways 658 ft 3 15 Does it Have Capacity? OK 16 Time to Drain 5.7 hr 90% volume in 48-hours minimum OK Check Swale With Driveways 17 Avg. Driveway Fill Slope in Swale (H/V) ft/ft 18 Enter Total Number of Driveways ea 0.0 ft 3 Deduct driveway slope 19 Enter Total Length of all Driveways ft 0.0 ft 3 Deduct driveway length 20 Lost Swale Length From Trees, etc. ft 0.0 ft 3 Deduct other 21 Adjusted Length of Infiltration Area 0.0 ft 22 Excess Capacity = Storage - Deductions - Runoff Volume (358.1) ft 3 23 Is Capacity Good? NO 24 Time to Drain 0.0 hr 90% volume in 48-hours minimum OK 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. ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches Hill's Century Farm Commercial Subdivision #2 - ACHD Borrow Ditch #2 P:\21-200\Documents\Reports\Storm Drainage\21-200 ACHD Borrow Ditch #2 Version 10.0, May 2018 10/8/2021, 12:49 PM APPENDIX C - GEOTECHNICAL ENGINEERING REPORT Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com MATERIALS TESTING & INSPECTION GEOTECHNICAL ENGINEERING REPORT of Hill's Century Farm Commercial Subdivision 3625 East Amity Road Meridian, ID Prepared for: Brighton Development, Inc. 12601 West Explorer Drive, Suite 200 Boise, ID 83713 MTI File Number B161292g P:\21-200\Documents\Reports\Storm Drainage\21-200 ACHD Borrow Ditch #2 Version 10.5, November 2018 10/8/2021, 12:48 PM 11 October 2016 Page # 2 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION TABLE OF CONTENTS INTRODUCTION ............................................................................................................................................................... 3 Project Description ................................................................................................................................................. 3 Authorization .......................................................................................................................................................... 3 Purpose ................................................................................................................................................................... 3 Scope of Investigation ............................................................................................................................................ 4 Warranty and Limiting Conditions ......................................................................................................................... 4 SITE DESCRIPTION .......................................................................................................................................................... 5 Site Access .............................................................................................................................................................. 5 Regional Geology ................................................................................................................................................... 6 General Site Characteristics .................................................................................................................................... 6 Regional Site Climatology and Geochemistry ........................................................................................................ 6 Geoseismic Setting ................................................................................................................................................. 7 SOILS EXPLORATION ...................................................................................................................................................... 7 Exploration and Sampling Procedures .................................................................................................................... 7 Laboratory Testing Program ................................................................................................................................... 7 Soil and Sediment Profile ....................................................................................................................................... 7 Volatile Organic Scan ............................................................................................................................................. 8 SITE HYDROLOGY........................................................................................................................................................... 8 Groundwater ........................................................................................................................................................... 9 Soil Infiltration Rates .............................................................................................................................................. 9 SLOPES AND SETBACKS ................................................................................................................................................ 10 FOUNDATION, SLAB, AND PAVEMENT DISCUSSION AND RECOMMENDATIONS ............................................................. 10 Foundation Design Recommendations ................................................................................................................. 10 Floor Slab-on-Grade ............................................................................................................................................. 11 AASHTO Recommended Pavement Sections ...................................................................................................... 12 Flexible Pavement Sections .................................................................................................................................. 12 Recommended Gravel Equivalent Pavement Sections ......................................................................................... 13 Flexible Pavement Section ................................................................................................................................... 13 Pavement Subgrade Preparation ........................................................................................................................... 14 Common Pavement Section Construction Issues ................................................................................................. 14 CONSTRUCTION CONSIDERATIONS ............................................................................................................................... 15 Earthwork ............................................................................................................................................................. 15 Dry Weather ......................................................................................................................................................... 16 Wet Weather ......................................................................................................................................................... 16 Soft Subgrade Soils .............................................................................................................................................. 16 Frozen Subgrade Soils .......................................................................................................................................... 17 Structural Fill ........................................................................................................................................................ 17 Backfill of Walls ................................................................................................................................................... 18 Excavations ........................................................................................................................................................... 18 Groundwater Control ............................................................................................................................................ 19 GENERAL COMMENTS .................................................................................................................................................. 19 REFERENCES ................................................................................................................................................................. 20 APPENDICES ................................................................................................................................................................. 21 Acronym List ........................................................................................................................................................ 21 Geotechnical General Notes ................................................................................................................................. 22 Geotechnical Investigation Test Pit Log ............................................................................................................... 23 AASHTO Pavement Thickness Design Procedures ............................................................................................. 33 R-Value Laboratory Test Data .............................................................................................................................. 36 Plate 1: Vicinity Map ............................................................................................................................................ 37 11 October 2016 Page # 3 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION INTRODUCTION This report presents results of a geotechnical investigation and analysis in support of data utilized in design of structures as defined in the 2012 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. Project Description The proposed development is in the southeastern portion of the City of Meridian, Ada County, ID, and occupies a portion of the NE¼NW¼ of Section 33, Township 3 North, Range 1 East, Boise Meridian. This project will consist of construction of a commercial subdivision to be developed into 20 commercial lots. It is anticipated that structures will be developed with spread/continuous footings and concrete floor slabs. Total settlements are limited to 1 inch. 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. Additionally, assumptions have been made for traffic loading of pavements. Retaining walls are not anticipated as part of the project. MTI has not been informed of the proposed grading plan. Authorization Authorization to perform this exploration and analysis was given in the form of a written authorization to proceed from Mr. Jon Wardle of Brighton Development, Inc. to Monica Saculles of Materials Testing and Inspection, Inc. (MTI), on 23 September 2016. Said authorization is subject to terms, conditions, and limitations described in the Professional Services Contract entered into between Brighton Development, Inc. and MTI. Our scope of services for the proposed development has been provided in our proposal dated 23 September 2016 and repeated below. Purpose The purpose of this Geotechnical Engineering Report is to determine various soil profile components and their engineering characteristics for use by either design engineers or architects in: Preparing or verifying suitability of foundation design and placement Preparing site drainage designs Indicating issues pertaining to earthwork construction Preparing light and heavy duty pavement section design requirements 11 October 2016 Page # 4 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION Scope of Investigation The scope of this investigation included review of geologic literature and existing available geotechnical studies of the area, visual site reconnaissance of the immediate site, subsurface exploration of the site, field and laboratory testing of materials collected, and engineering analysis and evaluation of foundation materials. Warranty and Limiting Conditions MTI warrants that findings and conclusions contained herein have been formulated in accordance with generally accepted professional engineering practice in the fields of foundation engineering, soil mechanics, and engineering geology only for the site and project described in this report. These engineering methods have been developed to provide the client with information regarding apparent or potential engineering conditions relating to the site within the scope cited above and are necessarily limited to conditions observed at the time of the site visit and research. Field observations and research reported herein are considered sufficient in detail and scope to form a reasonable basis for the purposes cited above. Limitations Only 10 test pits were advanced because one of the preselected locations for the test pits was in the vicinity of a drainfield. Exclusive Use This report was prepared for exclusive use of the property owner(s), at the time of the report, and their retained design consultants (“Client”). Conclusions and recommendations presented in this report are based on the agreed-upon scope of work outlined in this report together with the Contract for Professional Services between the Client and Materials Testing and Inspection, Inc. (“Consultant”). Use or misuse of this report, or reliance upon findings hereof, by parties other than the Client is at their own risk. Neither Client nor Consultant make representation of warranty to such other parties as to accuracy or completeness of this report or suitability of its use by such other parties for purposes whatsoever, known or unknown, to Client or Consultant. Neither Client nor Consultant shall have liability to indemnify or hold harmless third parties for losses incurred by actual or purported use or misuse of this report. No other warranties are implied or expressed. Report Recommendations are Limited and 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, MTI should be retained to explain the report contents to other design professionals as well as construction professionals. Since actual subsurface conditions on the site can only be verified by earthwork, note that construction recommendations are based on general assumptions from selective observations and selective field exploratory sampling. Upon commencement of construction, such conditions may be identified that require corrective actions, and these required corrective actions may impact the project budget. Therefore, construction recommendations in this report should be considered preliminary, and MTI should be retained to 11 October 2016 Page # 5 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION observe actual subsurface conditions during earthwork construction activities to provide additional construction recommendations as needed. Since geotechnical reports are subject to misinterpretation, do not separate the soil logs from the report. Rather, provide a copy of, or authorize for their use, the complete report to other design professionals or contractors. Locations of exploratory sites referenced within this report should be considered approximate locations only. For more accurate locations, services of a professional land surveyor are recommended. This report is also limited to information available at the time it was prepared. In the event additional information is provided to MTI following publication of our report, it will be forwarded to the client for evaluation in the form received. Environmental Concerns Comments in this report concerning either onsite conditions or observations, including soil appearances and odors, are provided as general information. These comments are not intended to describe, quantify, or evaluate environmental concerns or situations. Since personnel, skills, procedures, standards, and equipment differ, a geotechnical investigation report is not intended to substitute for a geoenvironmental investigation or a Phase II/III Environmental Site Assessment. If environmental services are needed, MTI can provide, via a separate contract, those personnel who are trained to investigate and delineate soil and water contamination. SITE DESCRIPTION Site Access Access to the site may be gained via Interstate 84 to the Eagle Road exit. Proceed south on Eagle Road approximately 2.5 miles to its intersection with Amity Road. From this intersection, proceed east 0.6 mile. The site resides on the south side of the road. Presently the site exists as an existing residence with associated farm land. The location is depicted on site map plates included in the Appendix. 11 October 2016 Page # 6 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION Regional Geology The project site is located within the western Snake River Plain of southwestern Idaho and eastern Oregon. The plain is a northwest trending rift basin, about 45 miles wide and 200 miles long, that developed about 14 million years ago (Ma) and has since been occupied sporadically by large inland lakes. Geologic materials found within and along the plain’s margins reflect volcanic and fluvial/lacustrine sedimentary processes that have led to an accumulation of approximately 1 to 2 km of interbedded volcanic and sedimentary deposits within the plain. Along the margins of the plain, streams that drained the highlands to the north and south provided coarse to fine-grained sediments eroded from granitic and volcanic rocks, respectively. About 2 million years ago the last of the lakes was drained and since that time fluvial erosion and deposition has dominated the evolution of the landscape. The project site is underlain by “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. General Site Characteristics This proposed development consists of approximately 20 acres of gently sloping terrain. These slopes traverse downhill from the east to west. Throughout the majority of the site, surficial soils consist of fine- grained clay soils. Vegetation primarily consists of agricultural crops. Regional drainage is north and west toward the Boise River. Stormwater drainage for the site is achieved by percolation through surficial soils. The site is situated so that it is unlikely that it will receive any stormwater drainage from off-site sources. Stormwater drainage collection and retention systems are not in place on the project site and were not noted within the vicinity of the project site. Regional Site Climatology and Geochemistry According to the Western Regional Climate Center, the average precipitation for the Treasure Valley is on the order of 10 to 12 inches per year, with an annual snowfall of approximately 20 inches and a range from 3 to 49 inches. The monthly mean daily temperatures range from 21°F to 95°F, with daily extremes ranging from -25°F to 111°F. Winds are generally from the northwest or southeast with an annual average wind speed of approximately 9 miles per hour (mph) and a maximum of 62 mph. Soils and sediments in the area are primarily derived from siliceous materials and exhibit low electro-chemical potential for corrosion of metals or concretes. Local aggregates are generally appropriate for Portland cement and lime cement mixtures. Surface water, groundwater, and soils in the region typically have pH levels ranging from 7.2 to 8.2. 11 October 2016 Page # 7 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION 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 7-10. Structures constructed on this site should be designed per IBC requirements for such a seismic classification. Our investigation did not reveal hazards resulting from potential earthquake motions including: slope instability, liquefaction, and surface rupture caused by faulting or lateral spreading. Incidence and anticipated acceleration of seismic activity in the area is low. SOILS EXPLORATION Exploration and Sampling Procedures Field exploration conducted to determine engineering characteristics of subsurface materials included a reconnaissance of the project site and investigation by test pit. Test pit sites pre staked by Brighton Development, Inc and 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 of overlying structures. In addition, samples were obtained from representative soil strata encountered. Samples obtained have been visually classified in the field by professional staff, identified according to test pit number and depth, placed in sealed containers, and transported to our laboratory for additional testing. Subsurface materials have been described in detail on logs provided in the Appendix. Results of field and laboratory tests are also presented in the Appendix. MTI recommends that these logs not be used to estimate fill material quantities. Laboratory Testing Program Along with our field investigation, a supplemental laboratory testing program was conducted to determine additional pertinent engineering characteristics of subsurface materials necessary in an analysis of anticipated behavior of the proposed structures. Laboratory tests were conducted in accordance with current applicable American Society for Testing and Materials (ASTM) and American Association of State Highway and Transportation Officials (AASHTO) specifications, and results of these tests are to be found on the accompanying logs located in the Appendix. The laboratory testing program for this report included: Atterberg Limits Testing – ASTM D4318, Grain Size Analysis – ASTM C117/C136, and Resistance Value (R-value) and Expansion Pressure of Compacted Soils – Idaho T-8. Soil and Sediment Profile The profile below represents a generalized interpretation for the project site. Note that on site soils strata, encountered between test pit locations, may vary from the individual soil profiles presented in the logs, which can be found in the Appendix. 11 October 2016 Page # 8 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION The materials encountered during exploration were quite typical for the geologic area mapped as Gravel of Sunrise Terrace. Surficial soils were predominately lean clays with sandy silt/silty sand fill materials being encountered above the surficial lean clays in test pits 1 and 3. Fills were light brown to brown, dry to slightly moist, very stiff/medium dense to dense, and contained fine to medium-grained sand and fine gravel. Lean clays were dark brown to light brown, dry to slightly moist, and medium stiff to hard. Generally sandy silt soils were encountered beneath the surficial lean clays and fill materials. Sandy silts were light brown to brown, dry to moist, stiff to hard, and contained fine to coarse-grained sand and varying degrees of calcium carbonate cementation. Poorly graded gravels with sand were encountered beneath the sandy silts. Poorly graded gravels with sand were light brown to yellowish brown, dry to moist, loose to very dense, and contained fine to coarse-grained sand, fine to coarse gravel, and 5-inch-minus cobbles. In the western portion of the site, poorly graded gravel with clay and sand sediments were typically encountered beneath the poorly graded gravels. Poorly graded gravels with clay and sand were light brown to reddish brown, slightly moist to saturated, medium dense to very dense, and contained fine to coarse-grained sand, fine to coarse gravel, and 3-inch-minus cobbles. In the eastern portion of the site, silty sand sediments were encountered beneath the poorly graded gravel with sand sediments. Silty sands were dark brown to light brown, slightly moist to moist, dense to very dense, and contained fine to coarse-grained sand and varying degrees of induration. In test pit 2, silt with sand soils were encountered beneath the poorly graded gravels with clay and sand. Silts with sand were dark brown to brown, stiff to very stiff, and contained fine-grained sand and varying degrees of induration. Competency of test pit walls varied little across the site. In general, fine grained soils remained stable while more granular sediments readily sloughed. However, moisture contents will also affect wall competency with saturated soils having a tendency to readily slough when under load and unsupported. Volatile Organic Scan No environmental concerns were identified prior to commencement of the investigation. Therefore, soils obtained during on-site activities were not assessed for volatile organic compounds by portable photoionization detector. Samples obtained during our exploration activities exhibited no odors or discoloration typically associated with this type of contamination. Groundwater encountered did not exhibit obvious signs of contamination. SITE HYDROLOGY Existing surface drainage conditions are defined in the General Site Characteristics section. Information provided in this section is limited to observations made at the time of the investigation. Either regional or local ordinances may require information beyond the scope of this report. 11 October 2016 Page # 9 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION Groundwater During this field investigation, groundwater was encountered in some test pits at depths ranging from 7.9 to 10.6 feet bgs. In other test pits, no groundwater was encountered to depths as great as 15.5 feet bgs. Soil moistures in the test pits were generally dry to moist within surficial soils and in areas where groundwater was not encountered. Within the poorly graded gravel sediments, soil moistures graded from dry to saturated as the water table was approached and penetrated. In the vicinity of the project site, groundwater levels are controlled in large part by residential and agricultural irrigation activity and leakage from nearby canals. Maximum groundwater elevations likely occur during the later portion of the irrigation season. During previous investigations performed in August 2013 and June 2014 within approximately ½-mile to the northwest and southwest of the project site, groundwater was noted within numerous test pits at depths ranging from 4.4 to 14.2 feet bgs. However, groundwater was not encountered to a depth of 18.1 feet bgs in an investigation performed in April 2015. Groundwater monitoring conducted by MTI to the site located to the southwest of the project site showed groundwater elevations ranging from 4.1 to 7.18 feet bgs. However, groundwater monitoring conducted to the south of the project site showed groundwater elevations ranging from 16.2 to 17 feet bgs. For construction purposes, groundwater depth for the elevated eastern portion of the site can be assumed to be greater than 8 feet bgs throughout the year and for the western lower portion of the site groundwater elevations can be assumed to remain greater than 5 feet bgs throughout the year. Since this is an estimated depth and seasonal groundwater levels fluctuate, actual levels should be confirmed by periodic groundwater data collected from piezometers installed in test pits 1, 4, and 5. If desired, MTI is available to perform this monitoring. Soil Infiltration Rates Soil permeability, which is a measure of the ability of a soil to transmit a fluid, was not tested in the field. Given the absence of direct measurements, for this report an estimation of infiltration is presented using generally recognized values for each soil type and gradation. Of soils comprising the generalized soil profile for this study, lean clay and silt with sand soils generally offer little permeability, with typical hydraulic infiltration rates of less than 2 inches per hour. Poorly graded gravel with clay and sand sediments generally exhibit infiltration rates of 2 inches to 6 inches per hour. Sandy silt soils will commonly exhibit infiltration rates from 2 to 4 inches per hour and silty sand sediments usually display rates of 4 to 8 inches per hour; though calcium carbonate cementation and induration may reduce these values to near zero. Poorly graded gravel sediments typically exhibit infiltration values in excess of 12 inches per hour. Due to the presence of shallow groundwater, indurated/cemented, and clayey soils, MTI recommends infiltration testing be conducted prior to construction. 11 October 2016 Page # 10 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION SLOPES AND SETBACKS Native slopes on the site were shallower 3 feet horizontal to 1 foot vertical (3:1). Therefore, slope setback requirements as outlined in the 2012 IBC are not applicable. Our investigation did not reveal any potential slope instabilities. FOUNDATION, SLAB, AND PAVEMENT DISCUSSION AND RECOMMENDATIONS Various foundation types have been considered for support of the proposed development. 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. Considering subsurface conditions and the proposed construction, it is recommended that the development be founded upon conventional spread footings and continuous wall footings. Total settlements should not exceed 1 inch if the following design and construction recommendations are observed. Presently, there are approximately 20 lots proposed for the project site. The following recommendations are not specific to the individual structures, but rather should be viewed as guidelines for the subdivision – wide development. Foundation Design Recommendations Based on data obtained from the site and test results from various laboratory tests performed, MTI recommends the following guidelines for the net allowable soil bearing capacity: Soil Bearing Capacity Footing Depth ASTM D1557 Subgrade Compaction Net Allowable Soil Bearing Capacity Footings must bear on competent, undisturbed, native sandy silt soils, poorly graded gravel with sand, or compacted structural fill. Existing lean clay soils and fill materials must be completely removed from below foundation elements.1 Excavation depths ranging from roughly 1.5 to 3.3 feet bgs should be anticipated to expose proper bearing soils.2 Not Required for Native Soil 95% for Structural Fill 2,000 lbs/ft2 A ⅓ increase is allowable for short-term loading, which is defined by seismic events or designed wind speeds. 1It will be required for MTI 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. 11 October 2016 Page # 11 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION The following sliding frictional coefficient values should be used: 1) 0.35 for footings bearing on native sandy silt (ML) soils and 2) 0.45 for footings bearing on native poorly graded gravels and granular structural fill. A passive lateral earth pressure of 349 pounds per square foot per foot (psf/ft) should be used for sandy silt (ML) soils. For compacted sandy gravel fill and poorly graded gravels, 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 2012 IBC minimum requirements. Total settlement should be limited to approximately 1 inch, and differential settlement should be limited to approximately ½ inch. Objectionable soil types encountered at the bottom of footing excavations should be removed and replaced with structural fill. Excessively loose or soft areas that are encountered in the footings subgrade will require over-excavation and backfilling with 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, MTI recommends continuous footings be suitably reinforced to make them as rigid as possible. For frost protection, the bottom of external footings should be 30 inches below finished grade. Floor Slab-on-Grade Uncontrolled fill was encountered in portions of the site. MTI recommends that these fill materials be excavated to a sufficient depth to expose competent, native soils or to a minimum depth of 1 foot below finished subgrade. If fill materials remain after over-excavation, the exposed subgrade must be compacted to at least 95 percent of the maximum dry density as determined by ASTM D1557. MTI personnel must be present during excavation to identify these materials. Native clay soils are moderately plastic and will be susceptible to shrink/swell movements associated with moisture changes. Areas of the site within the proposed structures should be excavated to sufficient depths to expose lean clay. The clay soils should be scarified to a depth of 6 inches and compacted between 92 to 98 percent of the maximum dry density as determined by ASTM D698. The moisture content should be within 2 percent of optimum. Structural fill should be placed as soon as possible after compaction of clay soils in order to limit moisture loss within the upper clays. Ground surfaces should be sloped away from structures at a minimum of 5 percent for a distance of 10 feet to provide positive drainage of surface water away from buildings. Grading must be provided and maintained following construction. 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 structural fill. Fill used to increase the elevation of the floor slab should meet 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 D1557. 11 October 2016 Page # 12 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION A free-draining granular mat (drainage fill course) should be provided below slabs-on-grade. This should be a minimum of 4 inches in thickness and properly compacted. The mat should consist of a sand and gravel mixture, complying with Idaho Standards for Public Works Construction (ISPWC) specifications for ¾-inch (Type 1) crushed aggregate. A moisture-retarder should be placed beneath floor slabs to minimize potential ground moisture effects on moisture-sensitive floor coverings. The 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 302.1R and ASTM E1745 publications. The granular mat should be compacted to no less than 95 percent of the maximum dry density as determined by ASTM D1557. Upon request, MTI can provide further consultation regarding installation. AASHTO Recommended Pavement Sections Per Brighton’s request, MTI has provided both AASHTO and Gravel Equivalent pavement recommendations. MTI recommends AASHTO Pavement Sections be used for site pavements. MTI has made assumptions for traffic loading variables based on the character of the proposed construction. The Client shall review and understand these assumptions to make sure they reflect intended use and loading of pavements both now and in the future. MTI collected a sample of near-surface soils for Resistance Value (R-value) testing representative of soils to depths of 2 feet bgs. This sample, consisting of sandy silt collected from test pit 9, yielded a R-value of 12. The R-value was converted to a CBR value of 5 for design calculations. The following are minimum thickness requirements for assured pavement function. Depending on site conditions, additional work, e.g. soil preparation, may be required to support construction equipment. These have been listed within the Soft Subgrade Soils section. Results of the test are graphically depicted in the Appendix. Flexible Pavement Sections The American Association of State Highway and Transportation Officials (AASHTO) design method has been used to calculate the following pavement sections. Calculation sheets provided in the Appendix indicate the soils constant, traffic loading, traffic projections, and material constants used to calculate the pavement sections. MTI recommends that materials used in the construction of asphaltic concrete pavements meet requirements of the ISPWC Standard Specification for Highway Construction. Construction of the pavement section should be in accordance with these specifications and should adhere to guidelines recommended in the section on Construction Considerations. AASHTO Flexible Pavement Specifications Pavement Section Component1 Driveways and Parking No Truck Access Driveways and Parking Truck Access Asphaltic Concrete 2.5 Inches 3.0 Inches Crushed Aggregate Base 4.0 Inches 4.0 Inches Structural Subbase 8.0 Inches 10.0 Inches Compacted Subgrade See Pavement Subgrade Preparation Section See Pavement Subgrade Preparation Section 1 It will be required for MTI personnel to verify subgrade competency at the time of construction. 11 October 2016 Page # 13 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION Asphaltic Concrete: Asphalt mix design shall meet the requirements of ISPWC, Section 810 Class III plant mix. Materials shall be placed in accordance with ISPWC Standard Specifications for Highway Construction. Aggregate Base: Material complying with ISPWC Standards for Crushed Aggregate Materials. Structural Subbase: Granular structural fill material complying with the requirements detailed in the Structural Fill section of this report except that the maximum material diameter is no more than 2/3 the component thickness. Gradation and suitability requirements shall be per ISPWC Section 801, Table 1. Recommended Gravel Equivalent Pavement Sections MTI recommends Gravel Equivalent Pavement Sections be used for proposed roadways. As required by Ada County Highway District (ACHD), MTI has used a traffic index of 6 to determine the necessary pavement cross-section for the site. MTI has made assumptions for traffic loading variables based on the character of the proposed construction. The Client should review these assumptions to make sure they reflect intended use and loading of pavements both now and in the future. MTI collected a sample of near-surface soils for Resistance Value (R-value) testing representative of soils to depths of 2 feet below existing ground surface. This sample, consisting of lean clay soils collected from test pit 9, yielded a R-value of 12. The following are minimum thickness requirements for assured pavement function. Depending on site conditions, additional work, e.g. soil preparation, may be required to support construction equipment. These have been listed within the Soft Subgrade Soils section. Results of the test are graphically depicted in the Appendix. Flexible Pavement Section The Gravel Equivalent Method, as defined in Section 500 of the State of Idaho Department of Transportation (ITD) Materials Manual, was used to develop the pavement sections. ACHD parameters for traffic index and substitution ratios, which were obtained from the ACHD Policy Manual, were also used in the design. Calculation sheets provided in the Appendix indicate the soils constant, traffic loading, traffic projections, and material constants used to calculate the pavement sections. MTI recommends that materials used in the construction of asphaltic concrete pavements meet the requirements of the ISPWC Standard Specification for Highway Construction. Construction of the pavement section should be in accordance with these specifications and should adhere to guidelines recommended in the section on Construction Considerations. Gravel Equivalent Method Flexible Pavement Specifications Pavement Section Component1 Roadway Section Asphaltic Concrete 2.5 Inches Crushed Aggregate Base 4.0 Inches Structural Subbase 12.0 Inches Compacted Subgrade See Pavement Subgrade Preparation Section 1 It will be required for MTI personnel to verify subgrade competency at the time of construction. 11 October 2016 Page # 14 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION Asphaltic Concrete: Asphalt mix design shall meet the requirements of ISPWC, Section 810 Class III plant mix. Materials shall be placed in accordance with ISPWC Standard Specifications for Highway Construction. Aggregate Base: Material complying with ISPWC Standards for Crushed Aggregate Materials. Structural Subbase: Material complying with requirements for granular structural fill (uncrushed) as defined in ISPWC. Pavement Subgrade Preparation Uncontrolled fill was encountered in portions of the site. MTI recommends that these fill materials be excavated to a sufficient depth to expose competent, native soils or to a minimum depth of 1 foot below finished subgrade. If fill materials remain after over-excavation, the exposed subgrade must be compacted to at least 95 percent of the maximum dry density as determined by ASTM D698. MTI personnel must be present during excavation to identify these materials. Native clay soils are moderately plastic and will be susceptible to shrink/swell movements associated with moisture changes. Areas of the site within the proposed pavement sections should be excavated to sufficient depths to expose clay soils. The clay soils should be scarified to a depth of 6 inches and compacted between 92 to 98 percent of the maximum dry density as determined by ASTM D698. The moisture content should be within 2 percent of optimum. Structural fill should be placed as soon as possible after compaction of clay soils in order to limit moisture loss within the upper clays. Common Pavement Section Construction Issues The subgrade upon which above pavement sections are to be constructed must be properly stripped, compacted (if indicated), inspected, and proof-rolled. Proof rolling of subgrade soils should be accomplished using a heavy rubber-tired, fully loaded, tandem-axle dump truck or equivalent. Verification of subgrade competence by MTI personnel at the time of construction is required. Fill materials on the site must demonstrate the indicated compaction prior to placing material in support of the pavement section. MTI anticipated that pavement areas will be subjected to moderate traffic. MTI does not anticipate pumping material to become evident during compaction, but subgrade clays and silts near and above optimum moisture contents may tend to pump. Pumping or soft areas must be removed and replaced with structural fill. Fill material and aggregates in support of the pavement section must be compacted to no less than 95 percent of the maximum dry density as determined by ASTM D698 for flexible pavements and by ASTM D1557 for rigid pavements. If a material placed as a pavement section component cannot be tested by usual compaction testing methods, then compaction of that material must be approved by observed proof rolling. Minor deflections from proof rolling for flexible pavements are allowable. Deflections from proof rolling of rigid pavement support courses should not be visually detectable. 11 October 2016 Page # 15 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION MTI recommends that rigid concrete pavement be provided for heavy garbage receptacles. This will eliminate damage caused by the considerable loading transferred through the small steel wheels onto asphaltic concrete. Rigid concrete pavement should consist of Portland Cement Concrete Pavement (PCCP) generally adhering to ITD specifications for Urban Concrete. PCCP should be 6 inches thick on a 4-inch drainage fill course (see Floor Slab-on-Grade section), and should be reinforced with welded wire fabric. Control joints must be on 12-foot centers or less. CONSTRUCTION CONSIDERATIONS Recommendations in this report are based upon structural elements of the project being founded on competent, undisturbed, native sandy silt soils, poorly graded gravel with sand sediments, or compacted structural fill. Structural areas should be stripped to an elevation that exposes these soil types. Earthwork Excessively organic soils, deleterious materials, or disturbed soils generally undergo high volume changes when subjected to loads, which is detrimental to subgrade behavior in the area of pavements, floor slabs, structural fills, and foundations. Agricultural crops 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 1 foot (minimum), and wasted or stockpiled for later use. Stripping depths should be adjusted in the field to assure that the entire root zone or disturbed zone (plow depths) or topsoil are removed prior to placement and compaction of structural fill materials. Exact removal depths should be determined during grading operations by MTI personnel, and should be based upon subgrade soil type, composition, and firmness or soil stability. If underground storage tanks, underground utilities, wells, or septic systems are discovered during construction activities, they must be decommissioned then removed or abandoned in accordance with governing Federal, State, and local agencies. Excavations developed as the result of such removal must be backfilled with structural fill materials as defined in the Structural Fill section. MTI should oversee subgrade conditions (i.e., moisture content) as well as placement and compaction of new fill (if required) after native soils are excavated to design grade. Recommendations for structural fill presented in this report can be used to minimize volume changes and differential settlements that are detrimental to the behavior of footings, pavements, and floor slabs. Sufficient density tests should be performed to properly monitor compaction. For structural fill beneath building structures, one in-place density test per lift for every 5,000 square feet is recommended. In parking and driveway areas, this can be decreased to one test per lift for every 10,000 square feet. 11 October 2016 Page # 16 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION Dry Weather If construction is to be conducted during dry seasonal conditions, many problems associated with soft soils may be avoided. However, some rutting of subgrade soils may be induced by shallow groundwater conditions related to springtime runoff or irrigation activities during late summer through early fall. Solutions to problems associated with soft subgrade soils are outlined in the Soft Subgrade Soils section. Problems may also arise because of lack of moisture in native and fill soils at time of placement. This will require the addition of water to achieve near-optimum moisture levels. Low-cohesion soils exposed in excavations may become friable, increasing chances of sloughing or caving. Measures to control excessive dust should be considered as part of the overall health and safety management plan. Wet Weather If construction is to be conducted during wet seasonal conditions (commonly from mid-November through May), problems associated with soft soils must be considered as part of the construction plan. During this time of year, fine-grained soils such as silts and clays will become unstable with increased moisture content, and eventually deform or rut. Additionally, constant low temperatures reduce the possibility of drying soils to near optimum conditions. Soft Subgrade Soils Shallow fine-grained subgrade soils that are high in moisture content should be expected to pump and rut under construction traffic. During periods of wet weather, construction may become very difficult if not impossible. The following recommendations and options have been included for dealing with soft subgrade conditions: Track-mounted vehicles should be used to strip the subgrade of root matter and other deleterious debris. Heavy rubber-tired equipment should be prohibited from operating directly on the native subgrade and areas in which structural fill materials have been placed. Construction traffic should be restricted to designated roadways that do not cross, or cross on a limited basis, proposed roadway or parking areas. Soft areas can be over-excavated and replaced with granular structural fill. Construction roadways on soft subgrade soils should consist of a minimum 2-foot thickness of large cobbles of 4 to 6 inches in diameter with sufficient sand and fines to fill voids. Construction entrances should consist of a 6-inch thickness of clean, 2-inch minimum, angular drain-rock and must be a minimum of 10 feet wide and 30 to 50 feet long. During the construction process, top dressing of the entrance may be required for maintenance. 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 1½ feet and allowed to air dry for 2 to 4 weeks. Further disking should be performed on a weekly basis to aid the aeration process. Alternative soil stabilization methods include use of geotextiles, lime, and cement stabilization. MTI is available to provide recommendations and guidelines at your request. 11 October 2016 Page # 17 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION Frozen Subgrade Soils Prior to placement of structural fill materials or foundation elements, frozen subgrade soils must either be allowed to thaw or be stripped to depths that expose non-frozen soils and wasted or stockpiled for later use. Stockpiled materials must be allowed to thaw and return to near-optimal conditions prior to use as structural fill. The onsite, shallow lean clay and silt soils are susceptible to frost heave during freezing temperatures. For exterior flatwork and other structural elements, adequate drainage away from subgrades is critical. Compaction and use of structural fill will also help to mitigate the potential for frost heave. Complete removal of frost susceptible soils for the full frost depth, followed by replacement with a non-frost susceptible structural fill, can also be used to mitigate the potential for frost heave. MTI is available to provide further guidance/assistance upon request. Structural Fill Soils recommended for use as structural fill are those classified as GW, GP, SW, and SP in accordance with the Unified Soil Classification System (USCS) (ASTM D2487). Use of silty soils (USCS designation of GM, SM, and ML) as structural fill may be acceptable. However, use of silty soils (GM, SM, and ML) as structural fill below footings is prohibited. These materials require very high moisture contents for compaction and require a long time to dry out if natural moisture contents are too high and may also be susceptible to frost heave under certain conditions. Therefore, these materials can be quite difficult to work with as moisture content, lift thickness, and compactive effort becomes difficult to control. If silty soil is used for structural fill, lift thicknesses should not exceed 6 inches (loose), and fill material moisture must be closely monitored at both the working elevation and the elevations of materials already placed. Following placement, silty soils must be protected from degradation resulting from construction traffic or subsequent construction. Recommended granular structural fill materials, those classified as GW, GP, SW, and SP, should consist of a 6-inch minus select, clean, granular soil with no more than 50 percent oversize (greater than ¾-inch) material and no more than 12 percent fines (passing No. 200 sieve). These fill materials should be placed in layers not to exceed 12 inches in loose thickness. Prior to placement of structural fill materials, surfaces must be prepared as outlined in the Construction Considerations section. Structural fill material should be moisture- conditioned to achieve optimum moisture content prior to compaction. 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. All fill materials must be monitored during placement and tested to confirm compaction requirements, outlined below, have been achieved. Each layer of structural fill must be compacted, as outlined below: Below Structures and Rigid Pavements: A minimum of 95 percent of the maximum dry density as determined by ASTM D1557. Below Flexible Pavements: A minimum of 92 percent of the maximum dry density as determined by ASTM D1557 or 95 percent of the maximum dry density as determined by ASTM D698. 11 October 2016 Page # 18 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION The ASTM D1557 test method must be used for samples containing up to 40 percent oversize (greater than ¾- inch) particles. If material contains more than 40 percent but less than 50 percent oversize particles, compaction of fill must be confirmed by proof rolling each lift with a 10-ton vibratory roller (or equivalent) until the maximum density has been achieved. Density testing must be performed after each proof rolling pass until the in-place density test results indicate a drop (or no increase) in the dry density, defined as maximum density or “break over” point. The number of required passes should be used as the requirements on the remainder of fill placement. Material should contain sufficient fines to fill void spaces, and must not contain more than 50 percent oversize particles. 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 for structural fill, 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. 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 1½ feet horizontal to 1 foot vertical (1½:1) for excavations up to 20 feet in height. Excavations in excess of 20 feet will require additional analysis. Note that these slope angles are considered stable for short-term conditions only, and will not be stable for long-term conditions. During the subsurface exploration, test pit sidewalls generally exhibited little indication of collapse; however, sloughing of fill materials and native granular sediments from test pit sidewalls was observed, particularly after penetration of the water table. For deep excavations, native granular sediments cannot be expected to remain in position. These materials are prone to failure and may collapse, thereby undermining upper soil layers. This is especially true when excavations approach depths near the water table. Care must be taken to ensure that excavations are properly backfilled in accordance with procedures outlined in this report. 11 October 2016 Page # 19 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION Shallow soil cementation (caliche) was observed through portions of the site and may cause difficulties during foundation development and utility placement. Cemented soils should be anticipated through the eastern portion of the site at depths of 2 to 4.5 feet bgs. 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 by the use of a treme. 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, MTI 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. GENERAL COMMENTS When plans and specifications are complete, or if significant changes are made in the character or location of the proposed development, consultation with MTI should be arranged as supplementary recommendations may be required. Suitability of subgrade soils and compaction of structural fill materials must be verified by MTI personnel prior to placement of structural elements. Additionally, monitoring and testing should be performed to verify that suitable materials are used for structural fill and that proper placement and compaction techniques are utilized. 11 October 2016 Page # 20 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION REFERENCES Ada County Highway District (ACHD) (2013). Ada County Highway District Policy Manual (October 2015). [Online] Available: <http://www.achdidaho.org/AboutACHD/PolicyManual.aspx> (2016). American Concrete Institute (ACI) (2004). Guide for Concrete Floor and Slab Construction: ACI 302.1R. Farmington Hills, MI: ACI. American Society of Civil Engineers (ASCE) (2013). Minimum Design Loads for Buildings and Other Structures: ASCE/SEI 7-10. Reston, VA: ASCE. American Society for Testing and Materials (ASTM) (2013). Standard Test Method for Materials Finer than 75-μm (No. 200) Sieve in Mineral Aggregates by Washing: ASTM C117. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2014). Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates: ASTM C136. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2012). Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort: ASTM D698. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2012). Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort: ASTM D1557. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2013). Standard Test Methods for Resistance Value (R-Value) and Expansion Pressure of Compacted Soils: ASTM D2844. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2011). Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System): ASTM D2487. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2010). Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils: ASTM D4318. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2011). Standard Specification for Plastic Water Vapor Retarders Used in Contact with Soil or Granular Fill Under Concrete Slabs: ASTM E1745. West Conshohocken, PA: ASTM. American Society of State Highway and Transportation Officials (AASHTO) (1993). AASHTO Guide for Design of Pavement Structures 1993. Washington D.C.: AASHTO. Desert Research Institute. Western Regional Climate Center. [Online] Available: <http://www.wrcc.dri.edu/> (2016). International Building Code Council (2012). International Building Code, 2012. Country Club Hills, IL: Author. Local Highway Technical Assistance Council (LHTAC) (2010). Idaho Standards for Public Works Construction, 2010. Boise, ID: Author. Othberg, K. L. and Stanford, L. A., Idaho Geologic Society (1992). Geologic Map of the Boise Valley and Adjoining Area, Western Snake River Plain, Idaho. (scale 1:100,000). Boise, ID: Joslyn and Morris. U.S. Department of Labor, Occupational Safety and Health Administration. CFR 29, Part 1926, Subpart P: Safety and Health Regulations for Construction, Excavations (1986). [Online] Available: <www.osha.gov> (2016). U.S. Geological Survey (2016). National Water Information System: Web Interface. [Online] Available: <http://waterdata.usgs.gov/nwis> (2016). 11 October 2016 Page # 21 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION APPENDICES ACRONYM LIST AASHTO: American Association of State Highway and Transportation Officials ACHD: Ada County Highway District ACI American Concrete Institute ASCE American Society of Civil Engineers ASTM: American Society for Testing and Materials bgs: below ground surface CBR: California Bearing Ratio D: natural dry unit weight, pcf ESAL Equivalent Single Axle Load GS: grab sample IBC: International Building Code IDEQ Idaho Department of Environmental Quality ISPWC: Idaho Standards for Public Works Construction ITD: Idaho Transportation Department LL: Liquid Limit M: water content MSL: mean sea level N: Standard "N" penetration: blows per foot, Standard Penetration Test NP: nonplastic OSHA Occupational Safety and Health Administration PCCP: Portland Cement Concrete Pavement PERM: vapor permeability PI: Plasticity Index PID: photoionization detector PVC: polyvinyl chloride Qc: cone penetrometer value, unconfined compressive strength, psi Qp: Penetrometer value, unconfined compressive strength, tsf Qu: Unconfined compressive strength, tsf RMR Rock Mass Rating RQD Rock Quality Designation R-Value Resistance Value SPT: Standard Penetration Test (140:pound hammer falling 30 in. on a 2:in. split spoon) USCS: Unified Soil Classification System USDA: United States Department of Agriculture UST: underground storage tank V: vane value, ultimate shearing strength, tsf 11 October 2016 Page # 22 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL GENERAL NOTES RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION Coarse-Grained Soils SPT Blow Counts (N) Fine-Grained Soils SPT Blow Counts (N) Very Loose: < 4 Very Soft: < 2 Loose: 4-10 Soft: 2-4 Medium Dense: 10-30 Medium Stiff: 4-8 Dense: 30-50 Stiff: 8-15 Very Dense: >50 Very Stiff: 15-30 Hard: >30 Moisture Content Cementation Description Field Test Description Field Test Dry Absence of moisture, dusty, dry to touch Weakly Crumbles or breaks with handling or slight finger pressure Moist Damp but not visible moisture Moderately Crumbles or beaks with considerable finger pressure Wet Visible free water, usually soil is below water table Strongly Will not crumble or break with finger pressure PARTICLE SIZE Boulders: >12 in. Coarse-Grained Sand: 5 to 0.6 mm Silts: 0.075 to 0.005 mm Cobbles: 12 to 3 in. Medium-Grained Sand: 0.6 to 0.2 mm Clays: <0.005 mm Gravel: 3 in. to 5 mm Fine-Grained Sand: 0.2 to 0.075 mm UNIFIED SOIL CLASSIFICATION SYSTEM Major Divisions Symbol Soil Descriptions Coarse-Grained Soils <50% passes No.200 sieve Gravel & Gravelly Soils <50% coarse fraction passes No.4 sieve GW Well-graded gravels; gravel/sand mixtures with little or no fines GP Poorly-graded gravels; gravel/sand mixtures with little or no fines GM Silty gravels; poorly-graded gravel/sand/silt mixtures GC Clayey gravels; poorly-graded gravel/sand/clay mixtures Sand & Sandy Soils >50% coarse fraction passes No.4 sieve SW Well-graded sands; gravelly sands with little or no fines SP Poorly-graded sands; gravelly sands with little or no fines 11 October 2016 Page # 23 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-1 Date Advanced: 30 Sept 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.5610619 Longitude: -116.3479919 Depth to Water Table: 9.4 Feet bgs Total Depth: 10.1 Feet bgs Notes: Piezometer installed to 10.1 feet bgs. Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-1.2 Silty Sand Fill (SM-FILL): Light brown to brown, dry, medium dense to dense, with fine to medium- grained sand. 1.2-3.2 Lean Clay (CL): Dark brown, dry, very stiff to hard. 4.0-4.5 3.2-6.7 Poorly Graded Gravel with Sand (GP): Light brown, dry, dense to very dense, with fine to coarse-grained sand, fine to coarse gravel, 4- inch-minus cobbles. 6.7-10.1 Poorly Graded Gravel with Clay and Sand (GP- GC): Light brown to reddish brown, slightly moist to saturated, dense to very dense, with fine to coarse-grained sand, fine to coarse gravel, and 4- inch-minus cobbles. --Groundwater slowly infiltrated through the sidewalls because of clay content and relative density of the soils. 11 October 2016 Page # 24 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-2 Date Advanced: 30 Sept 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.5602074 Longitude: -116.3474579 Depth to Water Table: Not Encountered Total Depth: 15.5 Feet bgs Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-1.5 Lean Clay (CL): Dark brown to brown, dry to slightly moist, medium stiff to very stiff. --Plow zone to a depth of 0.8 foot bgs. --Organics encountered to a depth of 1.1 feet bgs. 0.75-3.5 1.5-3.0 Sandy Silt (ML): Light brown, dry, very stiff to hard, with fine to medium-grained sand. --Very weak intermittent induration encountered throughout. 3.0-6.4 Poorly Graded Gravel with Sand (GP): Light brown to yellowish brown, dry, medium dense to dense, with medium to coarse-grained sand. 6.4-10.3 Poorly Graded Gravel with Clay and Sand (GP- GC): Light brown to reddish brown, slightly moist, dense to very dense, with fine to coarse- grained sand and fine to coarse gravel. 10.3-15.5 Silt with Sand (ML): Dark brown to brown, stiff to very stiff, with fine-grained sand. --Moderate induration encountered throughout. GS 13.5-14.0 A Lab Test ID M LL PI Sieve Analysis (% passing) - % - - #4 #10 #40 #100 #200 A 29.4 36 9 99 98 90 82 75.1 11 October 2016 Page # 25 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-3 Date Advanced: 30 Sept 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.5602646 Longitude: -116.3459320 Depth to Water Table: Not Encountered Total Depth: 12.3 Feet bgs Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-1.5 Sandy Silt with Gravel Fill (ML-FILL): Light brown to brown, dry to slightly moist, very stiff, with fine to medium-grained sand and fine gravel. --Plow zone to a depth of 1.1 feet bgs. --Organics to a depth of 1.5 feet bgs. 3.0-3.5 1.5-3.4 Sandy Silt (ML): Light brown, dry, very stiff to hard, with fine-grained sand. --Weak to moderate calcium carbonate cementation encountered below 2.0 feet bgs. 3.4-9.1 Poorly Graded Gravel with Sand (GP): Light brown, dry, medium dense to dense, with fine to coarse-grained sand and fine to coarse gravel. 9.1-12.3 Silty Sand (SM): Dark brown, slightly moist to moist, dense to very dense, with fine to coarse- grained sand. --Moderate induration encountered throughout. 11 October 2016 Page # 26 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-4 Date Advanced: 30 Sept 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.5602646 Longitude: -116.3445206 Depth to Water Table: Not Encountered Total Depth: 4.7 Feet bgs Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-2.8 Lean Clay (CL): Dark brown, dry to slightly moist, stiff to very stiff. --Plow zone to a depth of 1.2 feet bgs. --Organics to a depth of 1.3 feet bgs. 2.0-3.5 2.8-4.7 Sandy Silt (ML): Light brown to brown, dry, very stiff to hard, with fine to medium-grained sand. --Very strong calcium carbonate cementation encountered below 3.7 feet bgs. --Refusal on very strong cementation at 4.7 feet bgs. 11 October 2016 Page # 27 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-5 Date Advanced: 30 Sept 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.5611572 Longitude: -116.3450470 Depth to Water Table: Not Encountered Total Depth: 12.5 Feet bgs Notes: Piezometer installed to 12.5 feet bgs. Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-3.3 Lean Clay (CL): Dark brown to brown, dry to slightly moist, very stiff. --Plow zone to a depth of 1.2 feet bgs. --Organics to a depth of 1.3 feet bgs. GS 2.5-3.0 2.75 B 3.3-6.1 Sandy Silt (ML): Light brown, slightly moist to moist, very stiff to hard, with fine to coarse- grained sand. --Weak to moderate calcium carbonate cementation from 3.4 to 4.0 feet bgs. --Moist soils are likely from the irrigation ditch located in close proximity to the test pit. 6.1-10.8 Poorly Graded Gravel with Sand (GP): Yellowish brown to light brown, slightly moist, medium dense to dense, with fine to coarse-grained sand, fine to coarse gravel, and 5-inch-minus cobbles. 10.8-12.5 Silty Sand (SM): Light brown to brown, slightly moist to moist, dense to very dense, with fine to coarse-grained sand. --Moderate to strong induration encountered throughout. --Refusal on induration at 12.5 feet bgs. Lab Test ID M LL PI Sieve Analysis (% passing) - % - - #4 #10 #40 #100 #200 B 13.5 41 20 100 99 96 91 85.5 11 October 2016 Page # 28 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-6 Date Advanced: 30 Sept 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.5611420 Longitude: -116.3459778 Depth to Water Table: 10.6 Feet bgs Total Depth: 11.0 Feet bgs Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-2.1 Lean Clay (CL): Dark brown, dry to slightly moist, stiff to hard. --Organics to a depth of 1.1 feet bgs. --Plow zone to a depth of 1.2 feet bgs. 1.25-4.25 2.1-4.1 Sandy Silt (ML): Light brown, slightly moist to moist, very stiff to hard, with fine to coarse- grained sand. --Moderate to strong calcium carbonate cementation encountered below 2.6 feet bgs. 4.1-11.0 Poorly Graded Gravel with Sand (GP): Light brown, slightly moist to saturated, medium dense to dense, with fine to coarse-grained sand, fine to coarse gravel, and 3-inch-minus cobbles. 11 October 2016 Page # 29 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-7 Date Advanced: 30 Sept 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.5595016 Longitude: -116.3469925 Depth to Water Table: 8.1 Feet bgs Total Depth: 11.1 Feet bgs Notes: Piezometer installed to 11.1 feet bgs. Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-2.3 Lean Clay (CL): Dark brown to brown, dry to slightly moist, very stiff to hard. --Plow zone to a depth of 1.1 feet bgs. --Organics to a depth of 1.9 feet bgs. 2.75-4.5 2.3-3.5 Sandy Silt (ML): Brown to light brown, dry, stiff to very stiff, with fine to medium-grained sand. 3.5-9.6 Poorly Graded Gravel with Sand (GP): Yellowish brown to light brown, dry to saturated, loose to medium dense, with fine to coarse-grained sand and fine to coarse gravel. 9.6-11.1 Poorly Graded Gravel with Clay and Sand (GP- GC): Reddish brown, slightly moist to moist, dense to very dense, with fine to coarse-grained sand and fine to coarse gravel. 11 October 2016 Page # 30 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-8 Date Advanced: 30 Sept 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.5597954 Longitude: -116.3489151 Depth to Water Table: 9.6 Feet bgs Total Depth: 10.5 Feet bgs Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-2.1 Lean Clay (CL): Light brown to dark brown, dry to slightly moist, stiff to very stiff. 1.75-4.0 2.1-4.5 Sandy Silt (ML): Brown to light brown, slightly moist to moist, stiff to very stiff, with fine to medium-grained sand. --Very weak calcium carbonate cementation below 3.8 feet bgs. 4.5-10.5 Poorly Graded Gravel with Sand (GP): Light brown to yellowish brown, dry to saturated, medium dense to dense, with fine to coarse- grained sand and fine to coarse gravel. 11 October 2016 Page # 31 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-9 Date Advanced: 30 Sept 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.5593376 Longitude: -116.3486252 Depth to Water Table: 9.2 Feet bgs Total Depth: 10.2 Feet bgs Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-1.8 Lean Clay (CL): Dark brown, dry to slightly moist, hard. --Plow zone to a depth of 0.8 foot bgs. --Organics to a depth of 1.5 feet bgs. 4.5+ 1.8-4.4 Sandy Silt (ML): Brown, dry to slightly moist, stiff to very stiff, with fine to medium-grained sand. Bulk 1.8-2.3 R-Value 4.4-9.5 Poorly Graded Gravel with Sand (GP): Light brown to yellowish brown, dry to saturated, dense to very dense, with fine to coarse-grained sand, fine to coarse gravel, and 5-inch-minus cobbles. 9.5-10.2 Poorly Graded Gravel with Clay and Sand (GP- GC): Reddish brown, slightly moist to moist, dense to very dense, with fine to coarse-grained sand and fine to coarse gravel. 11 October 2016 Page # 32 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-10 Date Advanced: 30 Sept 2016 Logged by: Jacob Schlador, E.I.T. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.5597687 Longitude: -116.3480453 Depth to Water Table: 7.9 Feet bgs Total Depth: 8.8 Feet bgs Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-1.6 Lean Clay (CL): Dark brown, dry to slightly moist, stiff to hard. --Organics to a depth of 0.5 foot bgs. --Plow zone to a depth of 0.8 foot bgs. 2.0-4.5 1.6-4.6 Sandy Silt (ML): Light brown, slightly moist, stiff to very stiff, with fine to medium-grained sand. --Encountered weak calcium carbonate cementation below 2.8 feet bgs. 4.6-8.8 Poorly Graded Gravel with Sand (GP): Light brown to yellowish brown, dry to saturated, dense to very dense, with fine to coarse-grained sand, fine to coarse gravel, with 5-inch-minus cobbles. 11 October 2016 Page # 33 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION AASHTO PAVEMENT THICKNESS DESIGN PROCEDURES Pavement Section Design Location: Hill's Century Farm Subdivision, No Truck Access Average Daily Traffic Count: 200 All Lanes & Both Directions Design Life: 20 Years Percent of Traffic in Design Lane: 50% Terminal Seviceability Index (Pt): 2.5 Level of Reliability: 95 Subgrade CBR Value: 5 Subgrade Mr: 7,500 Calculation of Design-18 kip ESALs Daily Growth Load Design Traffic Rate Factors ESALs Passenger Cars: 78 2.0% 0.0008 553 Buses: 1 2.0% 0.6806 6,036 Panel & Pickup Trucks: 15 2.0% 0.0122 1,623 2-Axle, 6-Tire Trucks: 5 2.0% 0.1890 8,381 Concrete Trucks: 1.0 2.0% 4.4800 39,731 Dump Trucks: 0 2.0% 3.6300 0 Tractor Semi Trailer Trucks: 0 2.0% 2.3719 0 Double Trailer Trucks 0 2.0% 2.3187 0 Heavy Tractor Trailer Combo Trucks: 0 2.0% 2.9760 0 Average Daily Traffic in Design Lane: 100 Total Design Life 18-kip ESALs: 56,324 Actual Log (ESALs): 4.751 Trial SN: 2.30 Trial Log (ESALs): 4.757 Pavement Section Design SN: 2.41 Design Depth Structural Drainage Inches Coefficient Coefficient Asphaltic Concrete: 2.50 0.42 n/a Asphalt-Treated Base: 0.00 0.25 n/a Cement-Treated Base: 0.00 0.17 n/a Crushed Aggregate Base: 4.00 0.14 1.0 Subbase: 8.00 0.10 1.0 Special Aggregate Subgrade: 0.00 0.09 0.9 11 October 2016 Page # 34 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION AASHTO PAVEMENT THICKNESS DESIGN PROCEDURES Pavement Section Design Location: Hill's Century Farm Commercial Subdivision, Truck Access Average Daily Traffic Count: 200 All Lanes & Both Directions Design Life: 20 Years Percent of Traffic in Design Lane: 50% Terminal Seviceability Index (Pt): 2.5 Level of Reliability: 95 Subgrade CBR Value: 5 Subgrade Mr: 7,500 Calculation of Design-18 kip ESALs Daily Growth Load Design Traffic Rate Factors ESALs Passenger Cars: 60 2.0% 0.0008 426 Buses: 5 2.0% 0.6806 30,180 Panel & Pickup Trucks: 20 2.0% 0.0122 2,164 2-Axle, 6-Tire Trucks: 10 2.0% 0.1890 16,762 Concrete Trucks: 1.0 2.0% 4.4800 39,731 Dump Trucks: 1 2.0% 3.6300 32,193 Tractor Semi Trailer Trucks: 2 2.0% 2.3719 42,071 Double Trailer Trucks 1 2.0% 2.3187 20,563 Heavy Tractor Trailer Combo Trucks: 0 2.0% 2.9760 0 Average Daily Traffic in Design Lane: 100 Total Design Life 18-kip ESALs: 184,089 Actual Log (ESALs): 5.265 Trial SN: 2.79 Trial Log (ESALs): 5.265 Pavement Section Design SN: 2.82 Design Depth Structural Drainage Inches Coefficient Coefficient Asphaltic Concrete: 3.00 0.42 n/a Asphalt-Treated Base: 0.00 0.25 n/a Cement-Treated Base: 0.00 0.17 n/a Crushed Aggregate Base: 4.00 0.14 1.0 Subbase: 10.00 0.10 1.0 Special Aggregate Subgrade: 0.00 0.09 0.9 11 October 2016 Page # 35 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION GRAVEL EQUIVALENT METHOD – PAVEMENT THICKNESS DESIGN PROCEDURES Pavement Section Design Location: Hill's Century Farm Commercial Subdivision, Proposed Roadways Average Daily Traffic Count: 200 All Lanes & Both Directions Design Life: 20 Years Traffic Index: 6.00 Climate Factor: 1 R-Value of Subgrade: 12.00 Subgrade CBR Value: 5 Subgrade Mr: 7,500 R-Value of Aggregate Base: 80 R-Value of Granular Borrow: 60 Subgrade R-Value: 12 Expansion Pressure of Subgrade: 0.00 Unit Weight of Base Materials: 130 Total Design Life 18 kip ESAL's: 33,131 ASPHALTIC CONCRETE: Gravel Equivalent, Calculated: 0.384 Thickness: 0.196923077 Use = 2.5 Inches Gravel Equivalent, ACTUAL: 0.41 CRUSHED AGGREGATE BASE: Gravel Equivalent (Ballast): 0.768 Thickness: 0.329 Use = 4 Inches Gravel Equivalent, ACTUAL: 0.773 SUBBASE: Gravel Equivalent (Ballast): 1.690 Thickness: 0.917 Use = 12 Inches Gravel Equivalent, ACTUAL: 1.773 TOTAL Thickness: 1.542 Thickness Required by Exp. Pressure: 0.000 Design ACHD Depth Substitution Inches Ratios Asphaltic Concrete (at least 2.5): 2.50 1.95 Asphalt Treated Base (at least 4.2): 0.00 Cement Treated Base (at least 4.2): 0.00 Crushed Aggregate Base (at least 4.2): 4.00 1.10 Subbase (at least 4.2): 12.00 1.00 11 October 2016 Page # 36 of 38 b161292g_geotech.docx Environmental Services Geotechnical Engineering Construction Materials Testing Special Inspections 2791 S Victory View Way Boise, ID 83709 (208) 376-4748 Fax (208) 322-6515 www.mti-id.com mti@mti-id.com Copyright © 2016 Materials Testing & Inspection, Inc. MATERIALS TESTING & INSPECTION R-VALUE LABORATORY TEST DATA Source and Description: TP-9, 1.8’-2.3’ – Sandy Silt Date Obtained: September 30, 2016 Sample ID: 16-7668 Sampling and Preparation: ASTM D75: AASHTO T2: X ASTM D421: AASHTO T87: X Test Standard: ASTM D2844: AASHTO T190: Idaho T8: X Sample A B C Dry Density (lb/ft 3 ) 102.3 100.8 96.3 Moisture Content (%) 17.9 19.8 21.5 Expansion Pressure (psi) 0.09 0.00 0.00 Exudation Pressure (psi) 430 233 99 R-Value 14 12 10 R-Value @ 200 psi Exudation Pressure = 12 Exuda Exudation Wan 9.0 10.0 11.0 12.0 13.0 14.0 15.0 450400350300250200150100 50 R-Value Exudation Pressure (psi) R-Value @ Exudation Pressure SM Silty sands; poorly-graded sand/gravel/silt mixtures SC Clayey sands; poorly-graded sand/gravel/clay mixtures Fine Grained Soils >50% passes No.200 sieve Silts & Clays LL < 50 ML Inorganic silts; sandy, gravelly or clayey silts CL Lean clays; inorganic, gravelly, sandy, or silty, low to medium-plasticity clays OL Organic, low-plasticity clays and silts Silts & Clays LL > 50 MH Inorganic, elastic silts; sandy, gravelly or clayey elastic silts CH Fat clays; high-plasticity, inorganic clays OH Organic, medium to high-plasticity clays and silts Highly Organic Soils PT Peat, humus, hydric soils with high organic content Plate 2: Site Map ................................................................................................................................................... 38 P:\21-200\Documents\Reports\Storm Drainage\21-200 ACHD Borrow Ditch #1 Version 10.5, November 2018 10/8/2021, 12:41 PM