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MATERIALS TESTING & INSPECTION AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections GEOTECHNICAL ENGINEERING REPORT of McKay Farm Subdivision 5875 South Eagle Road Meridian,ID Prepared for: Fairbourne Development LLC PO Box 1335 Meridian, ID 83680 MTI File Number B191558g 2791 S Victory View Way• Boise, ID 83709•(208)376-4748• Fax(208)322-6515 www.mti-id.com • mti(cilmti-id.com _ MATERIALS 27 September 2019 TESTING & Page# I of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections Mr. Sam Johnson Fairbourne Development LLC PO Box 1335 Meridian, ID 83680 208-863-5889 Re: Geotechnical Engineering Report McKay Farm Subdivision 5875 South Eagle Road Meridian,ID Dear Mr. Johnson: In compliance with your instructions, MTI has conducted a soils exploration and foundation evaluation for the above referenced development. Fieldwork for this investigation was conducted on 4 September 2019. Data have been analyzed to evaluate pertinent geotechnical conditions. Results of this investigation, together with our recommendations, are to be found in the following report. We have provided a PDF copy for your review and distribution. Often, questions arise concerning soil conditions because of design and construction details that occur on a project. MTI would be pleased to continue our role as geotechnical engineers during project implementation. Additionally, MTI can provide materials testing and special inspection services during construction of this project. If you will advise us of the appropriate time to discuss these engineering services, we will meet with you at your convenience. MTI appreciates this opportunity to be of service to you and looks forward to working with you in the future. If you have questions, please call (208) 376-4748. Respectfully Submitted, Materials Testing & Inspection 13 Hunter Hayes, E.I. Reviewed by: Elizabeth Brown, P.E S\COAL FN Staff Engineer Geotechnical Service E a ��NS 0 ��yF a 14919 9-27-19 Reviewed by: Monica Saculles, P. s�qT 0- G.)Senior Geotechnical E q SAC��'\� 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#2 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections TABLE OF CONTENTS INTRODUCTION........................................................................................................................................................................3 ProjectDescription.........................................................................................................................................................3 Authorization..................................................................................................................................................................3 Purpose...........................................................................................................................................................................3 Scopeof Investigation.....................................................................................................................................................4 Warrantyand Limiting Conditions.................................................................................................................................4 SITEDESCRIPTION...................................................................................................................................................................5 SiteAccess......................................................................................................................................................................5 RegionalGeology...........................................................................................................................................................5 GeneralSite Characteristics............................................................................................................................................6 Regional Site Climatology and Geochemistry................................................................................................................6 SEISMICSITE EVALUATION.....................................................................................................................................................6 GeoseismicSetting.........................................................................................................................................................6 SeismicDesign Parameter Values..................................................................................................................................6 SOILSEXPLORATION...............................................................................................................................................................7 Explorationand Sampling Procedures............................................................................................................................7 LaboratoryTesting Program...........................................................................................................................................8 Soiland Sediment Profile...............................................................................................................................................8 VolatileOrganic Scan.....................................................................................................................................................8 SITEHYDROLOGY...................................................................................................................................................................9 Groundwater...................................................................................................................................................................9 SoilInfiltration Rates......................................................................................................................................................9 InfiltrationTesting........................................................................................................................................................ 10 FOUNDATION,SLAB,AND PAVEMENT DISCUSSION AND RECOMMENDATIONS....................................................................... 10 Foundation Design Recommendations......................................................................................................................... 10 Foundation Drain Recommendations............................................................................................................................ 11 Crawl Space Recommendations.................................................................................................................................... 11 Floor,Patio,and Garage Slab-on-Grade....................................................................................................................... 12 Recommended Pavement Sections............................................................................................................................... 12 FlexiblePavement Section............................................................................................................................................ 13 Pavement Subgrade Preparation................................................................................................................................... 13 Common Pavement Section Construction Issues.......................................................................................................... 14 CONSTRUCTION CONSIDERATIONS......................................................................................................................................... 14 Earthwork..................................................................................................................................................................... 14 DryWeather.................................................................................................................................................................. 15 WetWeather................................................................................................................................................................. 15 SoftSubgrade Soils....................................................................................................................................................... 15 FrozenSubgrade Soils.................................................................................................................................................. 16 StructuralFill................................................................................................................................................................ 16 Backfillof Walls........................................................................................................................................................... 17 Excavations................................................................................................................................................................... 17 GroundwaterControl.................................................................................................................................................... 18 GENERALCOMMENTS........................................................................................................................................................... 18 REFERENCES......................................................................................................................................................................... 19 APPENDICES..........................................................................................................................................................................20 AcronymList................................................................................................................................................................20 GeotechnicalGeneral Notes..........................................................................................................................................21 Geotechnical Investigation Test Pit Log.......................................................................................................................22 Gravel Equivalent Method—Pavement Thickness Design Procedures.........................................................................28 R-Value Laboratory Test Data......................................................................................................................................29 Plate1:Vicinity Map....................................................................................................................................................30 Plate2: Site Map...........................................................................................................................................................31 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 3 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections INTRODUCTION This report presents results of a geotechnical investigation and analysis in support of data utilized in design of structures as defined in the 2015 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 southern portion of the City of Meridian, Ada County, ID, and occupies a portion of the NEl/4SE'/4 of Section 32, Township 3 North, Range 1 East, Boise Meridian. This project will consist of 50 residential lots to be developed on approximately 10.5 acres. Total settlements are limited to I 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. Sam Johnson of Fairbourne Development LLC to Hunter Hayes of Materials Testing and Inspection (MTI), on 22 August 2019. Said authorization is subject to terms, conditions, and limitations described in the Professional Services Contract entered into between Fairbourne Development LLC and MTI. Our scope of services for the proposed development has been provided in our proposal dated 19 August 2019 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 residential pavement section design requirements 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#4 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections 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. The scope of work did not include design recommendations specific to individual residences. Warranty and Limiting Conditions MTI warrants that findings and conclusions contained herein have been formulated in accordance with generally accepted professional engineering practice in the fields of foundation engineering, soil mechanics, and engineering geology only for the site and project described in this report. These engineering methods have been developed to provide the client with information regarding apparent or potential engineering conditions relating to the site within the scope cited above and are necessarily limited to conditions observed at the time of the site visit and research. Field observations and research reported herein are considered sufficient in detail and scope to form a reasonable basis for the purposes cited above. Exclusive Use This report was prepared for exclusive use of the property owner(s), at the time of the report, and their retained design consultants ("Client"). Conclusions and recommendations presented in this report are based on the agreed-upon scope of work outlined in this report together with the Contract for Professional Services between the Client and Materials Testing and Inspection("Consultant"). Use or misuse of this report,or reliance upon findings hereof, by parties other than the Client is at their own risk. Neither Client nor Consultant make representation of warranty to such other parties as to accuracy or completeness of this report or suitability of its use by such other parties for purposes whatsoever, known or unknown, to Client or Consultant. Neither Client nor Consultant shall have liability to indemnify or hold harmless third parties for losses incurred by actual or purported use or misuse of this report. No other warranties are implied or expressed. Report Recommendations are Limited and Subiect to Misinterpretation There is a distinct possibility that conditions may exist that could not be identified within the scope of the investigation or that were not apparent during our site investigation. Findings of this report are limited to data collected from noted explorations advanced and do not account for unidentified fill zones,unsuitable soil types or conditions,and variability in soil moisture and groundwater conditions. To avoid possible misinterpretations of findings, conclusions, and implications of this report, MTI should be retained to explain the report contents to other design professionals as well as construction professionals. Since actual subsurface conditions on the site can only be verified by earthwork, note that construction recommendations are based on general assumptions from selective observations and selective field exploratory sampling. Upon commencement of construction, such conditions may be identified that require corrective actions, and these required corrective actions may impact the project budget. Therefore, construction recommendations in this report should be considered preliminary, and MTI should be retained to observe actual subsurface conditions during earthwork construction activities to provide additional construction recommendations as needed. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 5 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections 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 3.0 miles. The site is on the west side of Eagle Road. Presently the site exists as a residence with associated outbuildings to the north of the residence. The location is depicted on site map plates included in the Appendix. Regional Geology The project site is located within the western Snake River Plain of southwestern Idaho and eastern Oregon. The plain is a northwest trending rift basin, about 45 miles wide and 200 miles long,that developed about 14 million years ago(Ma)and has since been occupied sporadically by large inland lakes. Geologic materials found within and along the plain's margins reflect volcanic and fluvial/lacustrine sedimentary processes that have led to an accumulation of approximately 1 to 2 km of interbedded volcanic and sedimentary deposits within the plain. Along the margins of the plain, streams that drained the highlands to the north and south provided coarse to fine-grained sediments eroded from granitic and volcanic rocks, respectively. About 2 million years ago the last of the lakes was drained and since that time fluvial erosion and deposition has dominated the evolution of the landscape. The project site is underlain by "Sandy Alluvium of Side-Stream Valleys and Gulches" as mapped by Othberg and Stanford (1993). Locally, these deposits are composed of medium to coarse sand interbedded with silty fine sand and silt and are mostly derived from weathered granite and reworked Tertiary sediments of the Boise Foothills. The thickness of this unit is variable. Because of the relative youthfulness of these deposits they contain only minor pedogenic clay and calcium carbonate. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 6 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections General Site Characteristics This proposed development consists of approximately 10.5 acres of relatively flat terrain. Throughout the majority of the site, surficial materials consist of poorly graded gravel with clay fills or native lean clays. Vegetation primarily consists of mature trees, bunchgrass, and other native grass varieties typical of and to semi-arid environments. 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 do not currently exist 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 - 257 to 1117. 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. SEISMIC SITE EVALUATION 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. Seismic Design Parameter Values The United States Geological Survey National Seismic Hazard Maps (2008), includes a peak ground acceleration map. The map for 2% probability of exceedance in 50 years in the Western United States in standard gravity (g) indicates that a peak ground acceleration of 0.178 is appropriate for the project site based on a Site Class D. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 7 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections The following section provides an assessment of the earthquake-induced earthquake loads for the site based on the Risk-Targeted Maximum Considered Earthquake (MCER). The MCER spectral response acceleration for short periods, Stirs, and at 1-second period, Smi, are adjusted for site class effects as required by the 2015 IBC. Design spectral response acceleration parameters as presented in the 2015 IBC are defined as a 5% damped design spectral response acceleration at short periods, SDs, and at 1-second period, SDI. The USGS National Seismic Hazards Mapping Project includes a program that provides values for ground motion at a selected site based on the same data that were used to prepare the USGS ground motion maps. The maps were developed using attenuation relationships for soft rock sites; the source model, assumptions, and empirical relationships used in preparation of the maps are described in Petersen and others (1996). Seismic Design Values Seismic Design Parameter Design Value Site Class D "Stiff Soil" SS 0.287 S1 0.101 Fa 1.571 Fv 2.396 SMS 0.451 SMi 0.242 SDs 0.300 SDI 0.161 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 were located in the field by means of a Global Positioning System (GPS) device and are reportedly accurate to within sixteen 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. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 8 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections Laboratory Testing Program Along with our field investigation, a supplemental laboratory testing program was conducted to determine additional pertinent engineering characteristics of subsurface materials necessary in an analysis of anticipated behavior of the proposed structures. Laboratory tests were conducted in accordance with current applicable American Society for Testing and Materials (ASTM) specifications, and results of these tests are to be found on the accompanying logs located in the Appendix. The laboratory testing program for this report included: Atterberg Limits Testing—ASTM D4318, Grain Size Analysis—ASTM Cl 17/C 136, 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. Lean clay soils were encountered at ground surface with the exception of test pit 4 where poorly graded gravel with clay fill was found. The lean clay soils were brown, dry, and hard. The poorly graded gravel with clay fill was brown, dry, dense, and contained fine to coarse gravel. Organic material and disturbed materials, due to plowing activities, were generally noted throughout the surficial clay soils and fill materials. Silt and silt with sand soils were found beneath surficial soils and fill materials. The silt soils were light brown, dry to moist, stiff to hard, and contained fine-grained sand. Weak to very strong calcium carbonate cementation was noted throughout silt soils in test pits 4, 5, and 6. At depth, poorly graded gravel with clay and sand sediments were exposed. Poorly graded gravels were light brown to brown, slightly moist to saturated, medium dense to very dense, and contained fine to coarse-grained sand, fine to coarse gravel, and 6-inch minus cobbles. The clay content within these gravels increased with depth. During excavation, test pit sidewalls were generally stable. However, moisture contents will 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. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 9 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections SITE HYDROLOGY Existing surface drainage conditions are defined in the General Site Characteristics section. Information provided in this section is limited to observations made at the time of the investigation. Either regional or local ordinances may require information beyond the scope of this report. Groundwater During this field investigation, groundwater was encountered in test pits at depths ranging from 6.8 to 7.8 feet bgs. Soil moistures in the test pits were generally dry within surficial soils. Within the poorly graded gravels, soil moistures graded from slightly moist 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 commercial irrigation activity and leakage from nearby canals. Maximum groundwater elevations likely occur during the later portion of the irrigation season. MTI has previously performed 9 geotechnical investigations within 0.5 mile of the project site. Information from these investigations has been provided in the table below. Groundwater Data Date Approximate Distance Direction from Site Groundwater Depth JI6 AL from Site (mile) IN (feet b s) April 2016 0.5 West Not Encountered to 11.3 August 2013 0.4 Northeast 4.1 to 9.7 May 2017 0.3 Northeast 7.6 October 2016 0.3 Northeast 7.3 May 2017 0.5 Northeast 12.5 to 14.1 August 2017 0.5 Southeast 3.6 to 6.9 December 2015 0.4 Southeast 5.7 to 10.3 May 2018 0.2 Southeast 8.0 to 8.9 July 2019 0.5 South Not Encountered to 16.1 Based on evidence of this investigation and background knowledge of the area, MTI estimates groundwater depths to remain greater than approximately 4 feet bgs throughout the year. This depth can be confirmed through long-term groundwater monitoring from piezometers installed in test pits 1 and 4. 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 tested in the field. For this report, an estimation of infiltration is also 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 soils generally offer little permeability, with typical hydraulic infiltration rates of less than 2 inches per hour; though calcium carbonate cementation may reduce this value to near zero. Poorly graded gravel with clay and sand sediments typically exhibit infiltration rates of 2 to 6 inches per hour, though groundwater may reduce this value to near zero. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 10 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections Infiltration Testing Infiltration testing was conducted using an open test pit method. The test pit area will need to be re-excavated and compacted prior to construction of structures that will be sensitive to settlement. The test location was presoaked prior to testing. Pre-soaking increases soil moistures, which allows the tested soils to reach a saturated condition more readily during testing. Saturation of the tested soils is desirable in order to isolate the vertical component of infiltration by inhibiting horizontal seepage during testing. On 5 September 2019,testing on conducted within poorly graded gravel with clay and sand sediments at a depth of 4.5 feet bgs in test pit 1. A stabilized infiltration rate of 2.64 inches per hour was achieved during testing. Per the ACHD Policy Manual, a safety factor of 2 must be applied to tested infiltration rates less than 8 inches per hour.MTI recommends that all infiltration facilities be constructed in accordance with the local municipality requirements. FOUNDATION, SLAB,AND PAVEMENT DISCUSSION AND RECOMMENDATIONS Various foundation types have been considered for support of the proposed structures. Two requirements must be met in the design of foundations. First, the applied bearing stress must be less than the ultimate bearing capacity of foundation soils to maintain stability. Second, total and differential settlement must not exceed an amount that will produce an adverse behavior of the superstructure. Allowable settlement is usually exceeded before bearing capacity considerations become important; thus, allowable bearing pressure is normally controlled by settlement considerations. Considering subsurface conditions and the proposed construction, it is recommended that the structures 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 50 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: 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 11 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections Soil Bearing Capacity M -Footing Depth ASTM D1557 Net Allowable Sub grade Compaction Soil Bearing Capacity Footings must bear on competent, undisturbed, 1,5001bs/ft2 native silt soils, silt with sand soils, or compacted Not Required for Native 1 structural fill. Existing lean clay soils and fill Soil A /3 increase is allowable materials must be completely removed from below for short-term loading, foundation elements.' Excavation depths ranging 95% for Structural Fill Which is defined by seismic from roughly 0.6 to 1.2 feet bgs should be events or designed wind anticipated to expose proper bearing soils.2 1 1 seeds. 'It 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. The following sliding frictional coefficient values should be used: 1)0.35 for footings bearing on native silt and silt with sand soils and 2) 0.45 for footings bearing on poorly graded gravel with clay and sand sediments and granular structural fill. A passive lateral earth pressure of 297 pounds per square foot per foot (psf/ft) should be used for silt and silt with sand soils. For compacted sandy gravel fill and poorly graded gravel with clay and sand, 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 2015 IBC minimum requirements. Total settlement should be limited to approximately 1 inch, and differential settlement should be limited to approximately '/2 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 24 inches below finished grade. Foundation Drain Recommendations Considering the presence of shallow cemented soils across the site, MTI recommends that a foundation drain be installed. The drain should be placed at the footing elevation and be directed to a suitable discharge point at least 10 feet away from the structure. Discharge points should be protected to prevent erosion. Crawl Space Recommendations Considering the presence of shallow cemented soils and groundwater across the site, all residences constructed with crawl spaces should be designed in a manner that will inhibit water in the crawl spaces. Bottom of crawl spaces must be elevated at least 2 feet above seasonal high groundwater elevation. MTI recommends that roof drains carry stormwater at least 10 feet away from each residence. Grades should be at least 5 percent for a distance of 10 feet away from all residences. In addition, rain gutters should be placed around all sides of residences, and backfill around stem walls should be placed and compacted in a controlled manner. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 12 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections Floor, Patio, and Garage Slab-on-Grade Uncontrolled fill was encountered in portions of the site. MTI recommends that these fill materials be removed to a depth of at least 1 foot below existing grade. If fill materials remain after excavation,the exposed subgrade must be compacted to at least 95 percent of the maximum dry density as determined by ASTM D1557. The excavated fill materials can be replaced in accordance with the Structural Fill section. Once final grades have been determined, MTI is available to provide additional recommendations. Plow zones with organic materials were encountered across the site. MTI recommends that the organic materials be removed. If plow zones remain after organic materials have been removed, the exposed subgrade must be compacted to at least 95 percent of the maximum dry density as determined by ASTM D1557. MTI personnel must be present during excavation to identify these materials. Organic, loose, or obviously compressive materials must be removed prior to placement of concrete floors or floor-supporting fill. In addition, the remaining subgrade should be treated in accordance with guidelines presented in the Earthwork section. Areas of excessive yielding should be excavated and backfilled with 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. 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 3/4-inch (Type 1) crushed aggregate. The granular mat should be compacted to no less than 95 percent of the maximum dry density as determined by ASTM D1557. 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. Upon request, MTI can provide further consultation regarding installation. Recommended Pavement Sections As required by Ada County Highway District (ACED), 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 1.5 to 2.0 feet below existing ground surface. This sample, consisting of silt collected from test pit 4, yielded a R-value of 16. The following are minimum thickness requirements for assured pavement function. Depending on site conditions, additional work, e.g. soil preparation, may be required to support construction equipment. These have been listed within the Soft Subgrade Soils section. Results of the test are graphically depicted in the Appendix. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 13 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections Flexible Pavement Section The Gravel Equivalent Method, as defined in Section 500 of the State of Idaho Department of Transportation (ITD) Materials Manual, was used to develop the pavement section. ACHD parameters for traffic index and substitution ratios, which were obtained from the ACHD Policy Manual, were also used in the design. Calculation sheet provided in the Appendix indicate the soils constant, traffic loading, traffic projections, and material constants used to calculate the pavement sections. MTI recommends that materials used in the construction of asphaltic concrete pavements meet the requirements of the ISPWC Standard Specification for Highway Construction. Construction of the pavement section should be in accordance with these specifications and should adhere to guidelines recommended in the section on Construction Considerations. Gravel Equivalent Method Flexible Pavement Specifications Pavement Section Component' Roadway Section Asphaltic Concrete 2.5 Inches Crushed Aggregate Base 4.0 Inches Structural Subbase 20.0 Inches Compacted Subgrade See Pavement Subgrade Preparation Section 1It will be required for MTI personnel to verify subgrade competency at the time of construction. Asphaltic Concrete: Asphalt mix design shall meet the requirements of ISPWC, Section 810 Class III plant mix. Materials shall be placed in accordance with ISPWC Standard Specifications for Highway Construction. Aggregate Base: Material complying with ISPWC Standards for Crushed Aggregate Materials. Structural Subbase: Material complying with requirements for granular structural fill (uncrushed) as defined in ISPWC. Pavement Subuade Preparation Uncontrolled fill was encountered in portions of the site. MTI recommends that these fill materials be removed to a depth of at least 1'/2 feet below existing grade. If fill materials remain after excavation,the exposed sub rg ade must be compacted to at least 95 percent of the maximum density as determined by ASTM D698 for flexible pavements and ASTM D1557 for rigid pavements. The excavated fill materials can be replaced in accordance with the Structural Fill section. Once final grades have been determined,MTI is available to provide additional recommendations. Plow zones with organic materials were encountered in portions of the site. MTI recommends that the organic materials be removed. If plow zones remain after organic materials have been removed, the exposed sub_rg ade must be compacted to at least 95 percent of the maximum dry density as determined by ASTM D698 for flexible pavements and ASTM D 1557 for rigid payments. MTI personnel must be present during excavation to identify these materials. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 14 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections 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. Subgrade clays and silts near and above optimum moisture contents may pump during compaction. 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. CONSTRUCTION CONSIDERATIONS Recommendations in this report are based upon structural elements of the project being founded on competent, native silt soils, silt with sand soils,poorly graded gravel with clay and 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. Mature trees, brush, 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 1.0 foot (minimum), and wasted or stockpiled for later use. However, in areas where trees are/were present, deeper excavation depths should be anticipated. Stripping depths should be adjusted in the field to assure that the entire root zone or disturbed zone (plow depths) or topsoil are removed prior to placement and compaction of structural fill materials. Exact removal depths should be determined during grading operations by MTI personnel, and should be based upon subgrade soil type, composition, and firmness or soil stability. If underground storage tanks, underground utilities, wells, or septic systems are discovered during construction activities, they must be decommissioned then removed or abandoned in accordance with governing Federal, State,and local agencies. Excavations developed as the result of such removal must be backfilled with structural fill materials as defined in the Structural Fill section. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 15 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections MTI should oversee subgrade conditions (i.e., moisture content) as well as placement and compaction of new fill (if required) after native soils are excavated to design grade. Recommendations for structural fill presented in this report can be used to minimize volume changes and differential settlements that are detrimental to the behavior of footings, pavements, and floor slabs. Sufficient density tests should be performed to properly monitor compaction. For structural fill beneath 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. Dry Weather If construction is to be conducted during dry seasonal conditions,many problems associated with soft soils may be avoided. However,some rutting of subgrade soils may be induced by shallow groundwater conditions related to springtime runoff or irrigation activities during late summer through early fall. Solutions to problems associated with soft subgrade soils are outlined in the Soft Subgrade Soils section. Problems may also arise because of lack of moisture in native and fill soils at time of placement. This will require the addition of water to achieve near-optimum moisture levels. Low-cohesion soils exposed in excavations may become friable, increasing chances of sloughing or caving. Measures to control excessive dust should be considered as part of the overall health and safety management plan. Wet Weather If construction is to be conducted during wet seasonal conditions (commonly from mid-November through May),problems associated with soft soils must be considered as part of the construction plan. During this time of year, fine-grained soils such as silts and clays will become unstable with increased moisture content, and eventually deform or rut. Additionally, constant low temperatures reduce the possibility of drying soils to near optimum conditions. Soft Subgrade Soils Shallow fine-grained subgrade soils that are high in moisture content should be expected to pump and rut under construction traffic. During periods of wet weather, construction may become very difficult if not impossible. The following recommendations and options have been included for dealing with soft subgrade conditions: • Track-mounted vehicles should be used to strip the subgrade of root matter and other deleterious debris. Heavy rubber-tired equipment should be prohibited from operating directly on the native subgrade and areas in which structural fill materials have been placed. Construction traffic should be restricted to designated roadways that do not cross, or cross on a limited basis,proposed roadway or parking areas. • Soft areas can be over-excavated and replaced with granular structural fill. • Construction roadways on soft subgrade soils should consist of a minimum 2-foot thickness of large cobbles of 4 to 6 inches in diameter with sufficient sand and fines to fill voids. Construction entrances should consist of a 6-inch thickness of clean, 2-inch minimum, angular drain-rock and must be a minimum of 10 feet wide and 30 to 50 feet long. During the construction process, top dressing of the entrance may be required for maintenance. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 16 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections • Scarification and aeration of subgrade soils can be employed to reduce the moisture content of wet subgrade soils. After stripping is complete, the exposed subgrade should be ripped or disked to a depth of 11/2 feet and allowed to air dry for 2 to 4 weeks. Further disking should be performed on a weekly basis to aid the aeration process. • Alternative soil stabilization methods include use of geotextiles, lime, and cement stabilization. MTI is available to provide recommendations and guidelines at your request. Frozen Subgrade Soils Prior to placement of structural fill materials or foundation elements, frozen subgrade soils must either be allowed to thaw or be stripped to depths that expose non-frozen soils and wasted or stockpiled for later use. Stockpiled materials must be allowed to thaw and return to near-optimal conditions prior to use as structural fill. The onsite, shallow clayey and silty soils are susceptible to frost heave during freezing temperatures. For exterior flatwork and other structural elements, adequate drainage away from subgrades is critical. Compaction and use of 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 silt., soils 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 3/4-inch) material and no more than 12 percent fines (passing No. 200 sieve). These fill materials should be placed in layers not to exceed 12 inches in loose thickness. Prior to placement of structural fill materials, surfaces must be prepared as outlined in the Construction Considerations section. Structural fill material should be moisture-conditioned to achieve optimum moisture content prior to compaction. For structural fill below footings,areas of compacted backflll 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. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 17 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections Each layer of structural fill must be compacted, as outlined below: • Below Structures and Rigid Pavements: A minimum of 95 percent of the maximum dry density as determined by ASTM D1557. • Below Flexible Pavements: A minimum of 92 percent of the maximum dry density as determined by ASTM D1557 or 95 percent of the maximum dry density as determined by ASTM D698. The ASTM D1557 test method must be used for samples containing up to 40 percent oversize (greater than 3/4— inch)particles. If material contains more than 40 percent but less than 50 percent oversize particles,compaction of fill must be confirmed by proof rolling each lift with a 10-ton vibratory roller (or equivalent) until the maximum density has been achieved. Density testing must be performed after each proof rolling pass until the in-place density test results indicate a drop (or no increase) in the dry density, defined as maximum density or "break over"point. The number of required passes should be used as the requirements on the remainder of fill placement. Material should contain sufficient fines to fill void spaces, and must not contain more than 50 percent oversize particles. 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 11/2 feet horizontal to 1-foot vertical (11/2:1) for excavations up to 20 feet in height. Excavations in excess of 20 feet will require additional analysis. Note that these slope angles are considered stable for short- term conditions only, and will not be stable for long-term conditions. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 18 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections During the subsurface exploration, test pit sidewalls generally exhibited little indication of collapse. 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. Shallow soil cementation (caliche) was observed throughout portions of the site and may cause difficulties during foundation development and utility placement. Cemented soils should be anticipated in portions of the site at depths of 0.9 to 6.5 feet bgs. Groundwater Control Groundwater was encountered during the investigation and could possibly be encountered during 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 Based on the subsurface conditions encountered during this investigation and available information regarding the proposed development,the site is adequate for the planned construction. When plans and specifications are complete, and if significant changes are made in the character or location of the proposed structure,consultation with MTI must be arranged as supplementary recommendations may be required. Suitability of subgrade soils and compaction of structural fill materials must be verified by MTI personnel prior to placement of structural elements. Additionally, monitoring and testing should be performed to verify that suitable materials are used for structural fill and that proper placement and compaction techniques are utilized. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page# 19 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections REFERENCES Ada County Highway District (ACHD) (2017). Ada County Highway District Policy Manual (August 2017). [Online] Available: <http://www.achdidaho.org/AboutACHD/PolicyManual.aspx>(2019). 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. Desert Research Institute.Western Regional Climate Center. [Online]Available:<http://www.wrcc.dri.edu/>(2019). International Building Code Council(2015).International Building Code,2015.Country Club Hills,IL:Author. Local Highway Technical Assistance Council (LHTAC) (2017). Idaho Standards for Public Works Construction, 2017. Boise, ID: Author. National Oceanic and Atmospheric Administration. (2016).U.S. Earthquake Intensity Database:Web Interface. [Online] Available: <https://www.ngdc.noaa.gov/nndc/struts/form?t=101650&s=35&d=35>(2019). 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>(2019). U.S. Geological Survey (2019). National Water Information System: Web Interface. [Online] Available: <http://waterdata.usgs.gov/nwis>(2019). U.S. Geological Survey. (2011). U.S. Seismic Design Maps: Web Interface. [Online] Available: <https:Hearthquake.usgs.gov/designmaps/us/application.php>(2019). 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarriti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#20 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections APPENDICES ACRONYM LIST AASHTO: American Association of State Highway and Transportation Officials ACHD: Ada County Highway District ACI American Concrete Institute ASCE American Society of Civil Engineers ASTM: American Society for Testing and Materials bgs: below ground surface CBR: California Bearing Ratio D: natural dry unit weight,pcf ESAL Equivalent Single Axle Load GS: grab sample IBC: International Building Code LL: Liquid Limit M: water content MSL: mean sea level N: Standard"N"penetration: blows per foot, Standard Penetration Test NP: nonplastic OSHA Occupational Safety and Health Administration PCCP: Portland Cement Concrete Pavement PERM: vapor permeability PI: Plasticity Index PID: photoionization detector PVC: polyvinyl chloride QC: cone penetrometer value,unconfined compressive strength,psi Qp: Penetrometer value,unconfined compressive strength,tsf Qu: Unconfined compressive strength,tsf RMR Rock Mass Rating RQD Rock Quality Designation R-Value Resistance Value SPT: Standard Penetration Test(140:pound hammer falling 30 in.on a 2:in. split spoon) USCS: Unified Soil Classification System USDA: United States Department of Agriculture UST: underground storage tank V: vane value,ultimate shearing strength,tsf 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#21 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections GEOTECHNICAL GENERAL NOTES RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION Coarse-Grained Soils SPT Blow Counts (N) Fine-Grained Soils SPT Blow Counts (N) Very Loose: <4 Very Soft: <2 Loose: 4-10 Soft: 2-4 Medium Dense: 10-30 Medium Stiff: 4-8 Dense: 30-50 Stiff. 8-15 Very Dense: >50 Very Stiff: 15-30 Hard: >30 Moisture Content Cementation MEEW- 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 Strongly Will not crumble or break with finger water table g y 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 Gravel&Gravelly GW Well-graded gravels;gravel/sand mixtures with little or no fines Soils GP Poorly-graded gravels;gravel/sand mixtures with little or no fines Coarse-Grained <50% coarse fraction GM Silty gravels;poorly-graded gravel/sand/silt mixtures Soils passes No.4 sieve GC Clayey gravels;poorly-graded gravel/sand/clay mixtures <50% passes No.200 Sand&Sandy SW Well-graded sands;gravelly sands with little or no fines sieve Soils SP Poorly-graded sands;gravelly sands with little or no fines >50% coarse fraction SM Silty sands;poorly-graded sand/gravel/silt mixtures passes No.4 sieve SC Clayey sands;poorly-graded sand/gravel/clay mixtures ML Inorganic silts; sandy,gravelly or clayey silts Silts&Clays CL Lean clays;inorganic,gravelly,sandy,or silty,low to medium-plasticity clays Fine Grained LL<50 Soils>50% OL Organic,low-plasticity clays and silts passes No.200 MH Inorganic,elastic silts; sandy,gravelly or clayey elastic silts sieve Silts&Clays CH Fat clays;high-plasticity,inorganic clays LL>50 OH Organic,medium to high-plasticity clays and silts Highly Organic Soils PT Peat,humus,hydric soils with high organic content 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarriti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#22 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-1 Date Advanced: 4 Sept 2019 Logged by: Hunter Hayes. E.I. Excavated by: Creighton Contracting LLC Location: See Site Map Plates Latitude: 43.552425 Longitude: -116.355914 Depth to Water Table: 7.8 Feet bgs Total Depth: 11.6 Feet bgs Notes: Piezometer installed to 11.6 feet bgs. Depth Field Description and USCS Soil and Sample Sample Depth Lab Feet bgs) Sediment Classification Type (Feet bgs) Qp Test ID 0.0-1.0 Lean Clay (CL): Brown, dry, hard. 4.5+ --Organics and plow zone throughout. 1.0-3.0 Silt ML :Light brown, dry, stiff to very stiff, 2.0-2.5 Poorly Graded Gravel with Clay and Sand (GP-GC): Light brown to brown, slightly 3.0-11.6 moist to saturated, dense to very dense, with fine to coarse-grained sand, fine to coarse gravel, and 6-inch minus cobbles. --Clay content increases with depth. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#23 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-2 Date Advanced: 4 Sept 2019 Logged by: Hunter Hayes. E.I. Excavated by: Creighton Contracting LLC Location: See Site Map Plates Latitude: 43.551732 Longitude: -116.356088 Depth to Water Table: 7.6 Feet bgs Total Depth: 10.6 Feet bgs Depth Field Description and USCS Soil and Sample Sample Depth Lab (Feet bgs) Sediment Classification Type (Feet bgs) Qp Test ID Lean Clay (CL): Brown, dry, hard. 0.0-0.6 --Plow zone throughout. 4.5+ --Organics throughout. Silt (ML): Light brown, dry, and stiff to very 0.6-2.9 stiff. 2.0-2.5 --Organics to a depth of 1.0 oot. Poorly Graded Gravel with Clay and Sand (GP-GC): Light brown to brown, slightly 2.9-10.6 moist to saturated, medium dense to dense, with fine to coarse-grained sand, fine to coarse gravel, and 6-inch minus cobbles. --Clay content increases with depth. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#24 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-3 Date Advanced: 4 Sept 2019 Logged by: Hunter Hayes. E.I. Excavated by: Creighton Contracting LLC Location: See Site Map Plates Latitude: 43.550641 Longitude: -116.356045 Depth to Water Table: 7.5 Feet bgs Total Depth: 10.1 Feet bgs Depth Field Description and USCS Soil and Sample Sample Depth Lab Feet bgs) Sediment Classification Type (Feet bgs) Qp Test ID 0.0-0.9 Lean Clay (CL): Brown, dry, hard. 4.5+ --Organics and plow zone throughout. 0.9-2.6 Silt (ML): Light brown, dry, hard. 4.5+ Poorly Graded Gravel with Clay and Sand (GP-GC): Light brown to brown, slightly 2.6-10.1 moist to saturated, medium dense to dense, with fine to coarse-grained sand, fine to coarse gravel, and 6-inch minus cobbles. --Clay content increases with depth. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#25 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-4 Date Advanced: 4 Sept 2019 Logged by: Hunter Hayes. E.I. Excavated by: Creighton Contracting LLC Location: See Site Map Plates Latitude: 43.550807 Longitude: -116.355496 Depth to Water Table: 7.5 Feet bgs Total Depth: 8.5 Feet bgs Notes: Piezometer installed to 8.5 feet bgs. Depth Field Description and USCS Soil and Sample Sample Depth Lab Feet bgs) Sediment Classification Type Feet bgs) Qp Test ID Poorly Graded Gravel with Clay Fill (GP- 0.0-1.2 GC-FILL): Brown, dry, dense, with fine to coarse gravel. --Organics and plow zone throughout. Silt (ML): Light brown, dry, hard. --Weak to moderate calcium carbonate 1.2-4.0 cementation from 1.4 to 3.1 feet bgs. Bulk 1.5-2.0 4.5+ R-Value --Strong to very strong calcium carbonate cementation,from 3.1 to 4.0 eet bgs. Poorly Graded Gravel with Clay and Sand (GP-GC): Light brown to brown, slightly 4.0-8.5 moist to saturated, medium dense, with fine to coarse-grained sand,fine to coarse gravel, and 6-inch minus cobbles. --Clay content increases with depth. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#26 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-5 Date Advanced: 4 Sept 2019 Logged by: Hunter Hayes. E.I. Excavated by: Creighton Contracting LLC Location: See Site Map Plates Latitude: 43.550500 Longitude: -116.354776 Depth to Water Table: 6.8 Feet bgs Total Depth: 10.5 Feet bgs Depth Field Description and USCS Soil and Sample Sample Depth Lab Feet bgs) Sediment Classification Type (Feet bgs) Qp Test ID 0.0-1.0 Lean Clay (CL): Brown, dry, hard. 4.5+ --Organics and plow zone throughout. Silt with Sand (ML): Light brown, dry to moist, very stiff to hard, with fine-grained sand. 1.0-6.8 --Weak to moderate calcium carbonate GS 3.0-3.5 A* cementation from 1.0 to 4.4 feet bgs. --Strong to very strong calcium carbonate cementation,from 4.4 to 6.5 eet bgs. Poorly Graded Gravel with Clay and Sand (GP-GC): Light brown to brown, saturated, 6.8-10.5 medium dense to dense, with fine to coarse- grained sand, fine to coarse gravel, and 6- inch minus cobbles. --Clay content increases with depth. Lab Test ID M LL PI Sieve Analysis % passing) o - I - #4 #10 #40 #100 #200 A 13.4 NP I NP 96 94 65 47 38.9 * Sieve results were skewed by the presence of cementation. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#27 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-6 Date Advanced: 4 Sept 2019 Logged by: Hunter Hayes. E.I. Excavated by: Creighton Contracting LLC Location: See Site Map Plates Latitude: 43.551194 Longitude: -116.354698 Depth to Water Table: 7.2 Feet bgs Total Depth: 9.1 Feet bgs Depth Field Description and USCS Soil and Sample Sample Depth Lab (Feet bgs) Sediment Classification Type (Feet bgs) Qp Test ID Lean Clay (CL): Brown, dry, hard. 0.0-0.9 --Organics and low zone throughout. 4 5+ Silt with Sand (ML): Light brown, dry to 0.9-3.5 moist, hard, with fine-grained sand. 4.5+ --Weak calcium carbonate cementation throughout. Poorly Graded Gravel with Clay and Sand (GP-GC): Light brown to brown, moist to 3.5-9.1 saturated, medium dense to dense, with fine to coarse-grained sand,fine to coarse gravel, and 6-inch minus cobbles. --Clay content increases with depth. 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#28 of 31 INSPECTION bl91558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections GRAVEL EQUIVALENT METHOD—PAVEMENT THICKNESS DESIGN PROCEDURES Pavement Section Design Location: McKay Farm Subdivision,Residential Roadways Average Daily Traffic Count: All Lanes&Both Directions Design Life: 20 Years Traffic Index: 6.00 Climate Factor: 1 R-Value of Subgrade: 16.00 Subgrade CBR Value: 6 Subgrade Mr: 9,000 R-Value of Aggregate Base: 80 R-Value of Granular Borrow. 60 Subgrade R-Value: 16 Expansion Pressure of Subgrade: 1.89 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 CRUSH®AGGREGATE BASE: Gravel Equivalent(Ballast): 0.768 Thickness: 0.329 Use= 4 Inches Gravel Equivalent,ACTUAL: 0.773 SUBBASE: Gravel Equivalent(Ballast): 1.613 Thickness: 0.840 Use= 20 Inches Gravel Equivalent,ACTUAL: 2.440 TOTAL Thickness: 2.208 Thickness Required byExp.Pressure: 2.094 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 TYeatedBase(at least 4.2): 0.00 Crushed Aggregate Base(at least 4.2): 4.00 1.10 Subbase(at least 4.2): 20.00 1.00 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright2019 www.mti-id.com•mtiarntkid.com ght©Testing g&IMaterials Inspection _ MATERIALS 27 September 2019 TESTING & Page#29 of 31 INSPECTION b191558g_geotech AN ATLAS COMPANY o Environmental Services o Geotechnical Engineering o Construction Materials Testing o Special Inspections R-VALUE LABORATORY TEST DATA Source and Description: TP-4: 1.5'-2.0' Date Obtained: 4 September 2019 Sample ID: 19-7761 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) 90.1 88.2 87.6 Moisture Content % 14.9 15.3 16.4 Expansion Pressure (psi) 3.21 2.46 1.74 Exudation Pressure (psi) 390 263 183 R-Value 23 21 14 R-Value @ 200 psi Exudation Pressure = 16 R-Value @ Exudation Pressure 26.0 24.0 22.0 20.0 18.0 16.0 14.0 12.0 400 350 300 250 200 150 Exudation Pressure(psi) 2791 S Victory View Way•Boise, ID 83709•(208)376-4748• Fax(208)322-6515 Copyright 2019 www.mti-id.com•m Testing tiarnti-id.com ght©g&IMaterials Inspection Vicinity Map Plate 1 E FRANKLIN RD E FRA tzo y� vrI I. µl I� MAP NOTES: W FRA INKLIN Ro_ NKL]N M FRANKLIN RD" •Delorme Street Atlas •Not to Scale 44 r- 3U m :.tom 44 46 n — - 3 LEGEND ss 30 .� U) Approximate Site QVERLAVD R6 Q C QVERL4N6 Location E m m 3 m 4 O fig E VICTORY PD W V[�CTORY R® W UICTgRY Al] m N m � rn Site Locatio p� o " TF-rn � a a u; rn Lfl A McKay Farms Subdivision a cn 5875 South Eagle Road Meridian,ID b rn C es ° Modified from DeLorme by:HH r 12 September 2019 Drawing:B191558g � o m D r MATERIALS o a TESTING & tt ` INSPECTION COLUMBIA RD CdLUMBIA R=27 j AN ATLAS COMPANY cn _ 2791 S.Victory View Way Phone: 208 376-4748 i Boise,ID 83709-2835 Fax: 208 322-6515 E-mail: mti@mti-id.com Site Map Plate 2 NOTES: •Not to Scale I I I i I , I I i LEGEND Approximate Site — — — — _ Boundary I � TP-1 I i Approximate MTI Test Pit Location 8 I � Approximate MTI Test _------_---_— Pit Location with Piezometer I � i i I I I m I i i i i o TP-2 ® I d I N i 0 1 co iw ————————————— 0 Q TP-6 i w I � I � I McKay Farms Subdivision 5878 South Eagle Road I , Meridian,ID I � T® ; i i Drawn by:HH I 12 September 2019 TP-3 i I Drawing:B191558g I _ _ TP-5 AS MATERIALS JAWE I TO: LAKE HAZEL ROAD a TESTING & ------ INSPECTION INSPECTION I I AN ATLAS COMPANY I 2791 S.Victory View Way Phone: 208 376-4748 I Boise,ID 83709-2835 Fax: 208 322-6515 E-mail: mti@mti-id.com