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PZ - Geotechnical Report
MATERIALS TESTING 6 INSPECTION AN ATLAS COMPANY 18 November 2019 Page # 1 of 20 b191879g_limitedgeo ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections Mr. Dean Waite Todd Campbell Construction PO Box 140298 Boise, ID 83714 208-941-8607 Re: Limited Geotechnical Engineering Report The Cottages at Serenity Gardens 5875 & 5885 North Locust Grove Road Meridian, ID Dear Mr. Waite: In compliance with your instructions, MTI has conducted a limited soils exploration and pavement evaluation for the above referenced development. Fieldwork for this investigation was conducted on 5 November 2019. The proposed development is in the northeastern portion of the City of Meridian, Ada County, ID, and occupies a portion of the SE'/4NE'/4 of Section 30, Township 4 North, Range 1 East, Boise Meridian. This project will consist of a residential subdivision with approximately 50 lots. The site to be developed is approximately 10 acres in size. Retaining walls are not anticipated as part of the project. Assumptions have been made for traffic loading of pavements. 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. Dean Waite of Todd Campbell Construction to Monica Saculles of Materials Testing and Inspection (MTI), on 31 October 2019. Said authorization is subject to terms, conditions, and limitations described in the Professional Services Contract entered into between Todd Campbell Construction and MTI. Our scope of services for the proposed development has been provided in our proposal dated 31 October 2019 and repeated below. Scope of Investigation The scope of this investigation included review of geologic literature and existing available geotechnical studies of the area, visual site reconnaissance of the immediate site, subsurface exploration of the site, field and laboratory testing of materials collected, and engineering analysis and evaluation of pavement materials. Our scope of work did not include foundation design recommendations. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mtiOnriti-id.com Copyright 2019 Materials Testing 8lnspection MATERIALS TESTING & INSPECTION AN ATLAS COMPANY 18 November 2019 Page # 2 of 20 b191879g_limitedgeo ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections Regional Geology The project site is located within the western Snake River Plain of southwestern Idaho and eastern Oregon. The plain is a northwest trending rift basin, about 45 miles wide and 200 miles long, that developed about 14 million years ago (Ma) and has since been occupied sporadically by large inland lakes. Geologic materials found within and along the plain's margins reflect volcanic and fluvial/lacustrine sedimentary processes that have led to an accumulation of approximately 1 to 2 km of interbedded volcanic and sedimentary deposits within the plain. Along the margins of the plain, streams that drained the highlands to the north and south provided coarse to fine-grained sediments eroded from granitic and volcanic rocks, respectively. About 2 million years ago the last of the lakes was drained and since that time fluvial erosion and deposition has dominated the evolution of the landscape. The project site is underlain by the "Gravel of Whitney Terrace" as mapped by Othberg and Stanford (1993). Sediments of the Whitney terrace consist of sandy pebble and cobble gravel. The Whitney terrace is the second terrace above modern Boise River floodplain, is thickest toward its eastern extent, and is mantled with 2-6 feet of loess. General Site Characteristics This proposed development consists of approximately 10 acres of relatively flat and level terrain. Throughout the majority of the site, surficial soils consist of silts with varying amounts of sand. Vegetation primarily consists of mature trees, landscape shrubs and grass, volunteer growth, pasture grass, and other native grass varieties typical of arid to semi -arid environments. The project site is currently developed with two single-family residential structures and associated outbuildings fronting Locust Grove Road. The southeastern quarter of the site consisted of a residential structure with associated outbuildings and a gravel driveway and storage areas. The majority of the western half of the project site consisted of previously planted pasture grasses. A north -south trending drainage ditch bisects the northern half of the site. 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, but currently exist in the form of curb, gutter, and drop inlets in neighboring subdivisions. Exploration and Sampling Procedures Field exploration conducted to determine engineering characteristics of subsurface materials included a reconnaissance of the project site and investigation by test pit. Test pit sites were located in the field by means of a Global Positioning System (GPS) device and are reportedly accurate to within ten feet. Upon completion of investigation, each test pit was backfilled with loose excavated materials. Re -excavation and compaction of these test pit areas are required prior to construction of overlying structures. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 wWw.mti-id.com • mti(a)mti-id.com Copyright©gMnspect2019 ios Testing & Inspectlon MATERIALS TESTING fs INSPECTION AN ATLAS COMPANY 18 November 2019 Page # 3 of 20 b 191879g_limitedgeo ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections 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 Enclosures section. 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 Enclosures section. The materials encountered during exploration were quite typical for the geologic area mapped as Gravel of Whitney Terrace. Surficial soils consisted of silt with sand soils, with the exception of test pit 4. Silts with sand were light brown to dark brown, dry, stiff to very stiff, and contained fine to medium -grained sand. Underlying the surficial soils and at ground surface in test pit 4 were sandy silt soils. Sandy silts were brown, dry, stiff to hard, and contained fine to medium -grained sand and varying degrees of calcium carbonate cementation. Organic materials were noted to depths of roughly %2 foot and disturbed materials, as a result of plowing activities, usually reached a depth of 1'/2 feet. Beneath the sandy silt soils were silty gravel with sand sediments. Silty gravels with sand were light brown to brown, dry, dense to very dense, and contained fine to coarse-grained sand, 10 -inch -minus cobbles, and in some instances weak to strong calcium carbonate cementation. At depth throughout the site were poorly graded gravel with sand sediments. Poorly graded gravels with sand were tan to gray, dry, medium dense to dense, and contained medium to coarse-grained sand and 15 -inch -minus cobbles and boulders. 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. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 wWW.mti-id.com • mtina mti-id.com CopyrightTest0 ing g & Materials &Inspection MATERIALS TESTING 6 INSPECTION AN ATLAS COMPANY 18 November 2019 Page # 4 of 20 b191879g_1imitedgeo ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections Groundwater During this field investigation, groundwater was not encountered in test pits advanced to a maximum depth of 16.1 feet bgs. Soil moistures in the test pits were generally dry throughout. 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. MTI has previously performed 7 geotechnical investigations within 0.40 mile of the project site. Information from these investigations has been provided in the table below. Groundwater Data Date Approximate Distance from Site (mile) Direction from Site Groundwater Depth feet bgs) January 2005 0.10 North Not Encountered to 16.5 June 2004 0.10 West Not Encountered to 14.5 October 2013 0.25 South Not Encountered to 14.7 September 2005 0.25 North Not Encountered to 16.0 January 2006 0.30 North Not Encountered to 15.9 December 2015 0.35 Northwest Not Encountered to 12.8 August 2012 0.40 Northwest Not Encountered to 17.4 Furthermore, according to United States Geological Survey (USGS) monitoring well data within approximately Yz-mile of the project site, groundwater was measured at a depth of 39 feet bgs, which equates to a groundwater elevation of 2,561 feet above mean sea level (msl). For construction purposes, groundwater depth can be assumed to remain greater than 20 feet bgs throughout the year. This depth can be confirmed through long-term groundwater monitoring. Soil Infiltration Rates Soil permeability, which is a measure of the ability of a soil to transmit a fluid, was 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, silt with sand soils generally offer little permeability, with typical hydraulic infiltration rates of less than 2 inches per hour. Sandy silt soils will commonly exhibit infiltration rates from 2 to 4 inches per hour and silty gravel with sand sediments usually display rates of 4 to 8 inches per hour; though calcium carbonate cementation may reduce these values to near zero. Poorly graded gravel with sand sediments typically exhibit infiltration values in excess of 12 inches per hour. Infiltration testing is generally not required within these sediments because of their free -draining nature. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 Copyright©2019 Materials www.mti-id.com • mtiOmti-id.com Testing & Inspection MATERIALS TESTING S INSPECTION AN ATLAS COMPANY 18 November 2019 Page # 5 of 20 b191879g_limitedgeo ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections Infiltration Testing Infiltration testing was conducted in general accordance with the Ada County Highway District (ACHD) Policy Manual. Test pit areas will need to be re -excavated and compacted prior to construction of structures that will be sensitive to settlement. Test locations were 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. Testing was conducted on 5 November 2019. Details and results of testing are as follows: Infiltration Testing Results *Per the ACHD Policy Manual, the maximum design infiltration rate is 8 inches per hour. In accordance with the ACHD Policy Manual, a maximum design infiltration rate of 8 inches per hour was recommended. MTI recommends that all infiltration facilities be constructed in accordance with the local municipality requirements. Recommended Pavement Sections As required by Ada County Highway District (ACHD), MTI has used a traffic index of 6 to determine the necessary pavement cross-section for the site. MTI has made assumptions for traffic loading variables based on the character of the proposed construction. The Client should review these assumptions to make sure they reflect intended use and loading of pavements both now and in the future. MTI collected a sample of near - surface soils for Resistance Value (R -value) testing representative of soils to depths of 2 feet below existing ground surface. This sample, consisting of sandy silt collected from test pit 2, yielded a R -value of 43. 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 Enclosures section. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mti(ilTesting mti-id.com Copyright0 g&I2019 Materials Inspection Test Stabilized Design Test Depth Soil Type Infiltration Rate Infiltration Rate Location feet b s (inches/hour) (inches/hour) TP -2 8.5 Poorly Graded Gravel >24 8.0* with Sand TP -4 12.3 Poorly Graded Gravel >24 8.0* with Sand *Per the ACHD Policy Manual, the maximum design infiltration rate is 8 inches per hour. In accordance with the ACHD Policy Manual, a maximum design infiltration rate of 8 inches per hour was recommended. MTI recommends that all infiltration facilities be constructed in accordance with the local municipality requirements. Recommended Pavement Sections As required by Ada County Highway District (ACHD), MTI has used a traffic index of 6 to determine the necessary pavement cross-section for the site. MTI has made assumptions for traffic loading variables based on the character of the proposed construction. The Client should review these assumptions to make sure they reflect intended use and loading of pavements both now and in the future. MTI collected a sample of near - surface soils for Resistance Value (R -value) testing representative of soils to depths of 2 feet below existing ground surface. This sample, consisting of sandy silt collected from test pit 2, yielded a R -value of 43. 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 Enclosures section. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mti(ilTesting mti-id.com Copyright0 g&I2019 Materials Inspection MATERIALS TESTING & INSPECTION AN ATLAS COMPANY ❑ Environmental Services ❑ Geotechnical Engineering Flexible Pavement Section ❑ Construction Materials Testing 18 November 2019 Page # 6 of 20 b 191879g_limitedgeo ❑ Special Inspections 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. A calculation sheet provided in the Enclosures section indicates the soils constant, traffic loading, traffic projections, and material constants used to calculate the pavement section. 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 Common Pavement Section Construction Issues. Gravel Equivalent Method Flexible Pavement Specifications Pavement Section Component' Roadway Section Asphaltic Concrete 2.5 Inches Crushed Aggregate Base 4.0 Inches Structural Subbase 6.0 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 Sub2rade Preparation Plow zones, which should be treated as uncontrolled fill, were encountered in portions of the site. MTI recommends that these plow zones be excavated to a sufficient depth to expose competent, native soils or to a minimum depth of 1 foot below finished subgrade. If plow zones remain after over -excavation the exposed subgrade must be compacted to at least 95 percent of the maximum dry ensity as determined by ASTM D698. 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 www.mti-id.com • mti(a)mti-id.com Copyrighl0 Testingg & Mater Inspection l CMATERIALS IFTESTING & INSPECTION AN ATLAS COMPANY 18 November 2019 Page # 7 of 20 b191879g_limitedgeo ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ 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 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, as well as compacted native subgrade soils, in support of the pavement section must be compacted to no less than 95 percent of the maximum dry density as determined by ASTM D698 for flexible pavements and by ASTM D1557 for rigid pavements. If a material placed as a pavement section component cannot be tested by usual compaction testing methods, then compaction of that material must be approved by observed proof rolling. Minor deflections from proof rolling for flexible pavements are allowable. Deflections from proof rolling of rigid pavement support courses should not be visually detectable. MTI recommends that rigid concrete pavement be provided for heavy garbage receptacles. This will eliminate damage caused by the considerable loading transferred through the small steel wheels onto asphaltic concrete. Rigid concrete pavement should consist of Portland Cement Concrete Pavement (PCCP) generally adhering to ITD specifications for Urban Concrete. PCCP should be 6 inches thick on a 4 -inch drainage fill course, and should be reinforced with welded wire fabric. The drainage fill course should consist of a sand and gravel mixture, complying with Idaho Standards for Public Works Construction (ISPWC) specifications for'/4-inch (Type 1) crushed aggregate. Control joints must be on 12 -foot centers or less. Soft Subgrade Soils Shallow fine-grained subgrade soils that are high in moisture content should be expected to pump and rut under construction traffic. During periods of wet weather, construction may become very difficult if not impossible. The following recommendations and options have been included for dealing with soft subgrade conditions: Track -mounted vehicles should be used to strip the subgrade of root matter and other deleterious debris. Heavy rubber -tired equipment should be prohibited from operating directly on the native subgrade and areas in which structural fill materials have been placed. Construction traffic should be restricted to designated roadways that do not cross, or cross on a limited basis, proposed roadway or parking areas. Soft areas can be over -excavated and replaced with granular structural fill. Construction roadways on soft subgrade soils should consist of a minimum 2 -foot thickness of large cobbles of 4 to 6 inches in diameter with sufficient sand and fines to fill voids. Construction entrances should consist of a 6 -inch thickness of clean, 2 -inch minimum, angular drain -rock and must be a minimum of 10 feet wide and 30 to 50 feet long. During the construction process, top dressing of the entrance may be required for maintenance. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mti(cD-mti-id.com Copyright 02019 Testing g&Inspection j CMATERIALS IFTESTING £r INSPECTION AN ATLAS COMPANY 18 November 2019 Page # 8 of 20 b191879g_limitedgeo ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections Scarification and aeration of subgrade soils can be employed to reduce the moisture content of wet subgrade soils. After stripping is complete, the exposed subgrade should be ripped or disked to a depth of I Meet 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. 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 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 Pavement Subgrade Preparation section and Common Pavement Section Construction Issues 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. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mTesting tiarriti-id.com Copyright©Materials g&Ilnspection MATERIALS TESTING 6 INSPECTION AN ATLAS COMPANY 18 November 2019 Page # 9 of 20 b 191879g_limitedgeo ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special I The ASTM D 1557 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. 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. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mti(a)mti-id.com Copyrighlm Testingg&I2019 nspection MATERIALS TESTING & INSPECTION AN ATLAS COMPANY ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing 18 November 2019 Page # 10 of 20 b191979g_limitedgeo ❑ Special Inspections Since actual subsurface conditions on the site can only be verified by earthwork, note that construction recommendations are based on general assumptions from selective observations and selective field exploratory sampling. Upon commencement of construction, such conditions may be identified that require corrective actions, and these required corrective actions may impact the project budget. Therefore, construction recommendations in this report should be considered preliminary, and MTI should be retained to observe actual subsurface conditions during earthwork construction activities to provide additional construction recommendations as needed. Since geotechnical reports are subject to misinterpretation, do not separate the soil logs from the report. Rather, provide a copy of, or authorize for their use, the complete report to other design professionals or contractors. Locations of exploratory sites referenced within this report should be considered approximate locations only. For more accurate locations, services of a professional land surveyor are recommended. 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. General Comments Based on the subsurface conditions encountered during this investigation and available information regarding the proposed pavements, 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 pavements, consultation with MTI must be arranged as supplementary recommendations may be required. 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. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mtiCDTesting .mti-id.com Copyright0 g&I019 Materials Inspection j CMATERIALS IFTESTING 6 INSPECTION 18 November 2019 Page # 11 of 20 b 191879g_limitedgeo AN ATLAS COMPANY ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections 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 OE NsF�NC/,y�` Q� 18300 Jacob Schlador, P.E. s� 11-18-19 0 Geotechnical Engineer OF SOP Q S C H\-��o Enclosures: Geotechnical General Notes Reviewed by: Monica Saculles, P.E. Senior Geotechnical Engineer Geotechnical Investigation Test Pit Logs Gravel Equivalent Method — Pavement Thickness Design Procedures Vicinity Map Site Map 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 Copyright®Mated www.mti-id.com • mti(o)mti-id.com Testing&InMaedtion MATERIALS TESTING fs INSPECTION 18 November 2019 Page # 12 of 20 b191879g_limitedgeo AN ATLAS COMPANY ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections GEOTECHNICAL GENERAL NOTES Moisture Content RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION Field Test 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 CH Fat clays; high -plasticity, inorganic clays Hard: >30 Moisture Content Description Field Test Dry Absence of moisture, dusty, dry to touch Moist Damp but not visible moisture Wet Visible free water, usually soil is below water table 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 Cementation Description Field Test Weakly Crumbles or breaks with handling or GP Poorly -graded gravels; gravel/sand mixtures with little or no fines slight finger pressure Moderately Crumbles or beaks with considerable SW Well -graded sands; gravelly sands with little or no fines finger pressure Strongly Will not crumble or break with finger Fine Grained Soils >50% passes No.200 sieve 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 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 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mtiOmti-id.com Copyright g Unspect19 ios Testing & Inspectlon MATERIALS 18 November 2019 TESTING & Page # 13 of 20 INSPECTION b191879g_limitedgeo AN ATLAS COMPANY ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP -1 Date Advanced: 5 Nov 2019 Logged by: Nick Stevens, G.I.T. Excavated by: Creighton Contracting, LLC Location: See Site Map Plates Latitude: 43.65829 Longitude: -116.37897 Depth to Water Table: Not Encountered Total Depth: 16.1 Feet bgs Depth Field Description and USCS Soil and Sample Sample Depth Qp Lab (Feet bgs) Sediment Classification Type (Feet bgs) Test ID Silt with Sand (ML): Light brown, dry, stiff to very stiff, with fine to medium -grained 0.0-1.9 sand. 1.75-2.5 --Organic materials noted to 0. S foot bgs. --Plow zone encountered throughout. Sandy Silt (ML): Brown, dry, very stiff to 1.9-5.7 hard, with fine to medium -grained sand. 3.5-4.5+ --Intermittent weak calcium carbonate cementation noted throughout. Silty Gravel with Sand (GM): Light brown to brown, dry, dense to very dense, with fine to 5.7-7.9 coarse-grained sand and 4 -inch minus cobbles. --Intermittent weak calcium carbonate cementation throughout. Poorly Graded Gravel with Sand (GP): Tan to gray, dry, medium dense to dense, with 7.9-16.1 medium to coarse-grained sand and 14 -inch - minus boulders. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mtiCa.mti-id.com Copyright Q2019 Materials Testing 8lnspec0on j CMATERIALS IFTESTING £r INSPECTION 18 November 2019 Page # 14 of 20 b 191879g_limitedgeo AN ATLAS COMPANY ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP -2 Date Advanced: 5 Nov 2019 Logged by: Nick Stevens, G.I.T. Excavated by: Creighton Contracting, LLC Location: See Site Map Plates Latitude: 43.65769 Longitude: -116.37864 Depth to Water Table: Not Encountered Total Depth: 11.9 Feet bgs Notes: Infiltration testing conducted at 8.5 feet bgs. Depth Field Description and USCS Soil and Sample Sample Depth QP Lab (Feet bgs) Sediment Classification Type Feet bgs)__ Test ID Silt with Sand (ML): Light brown, dry, very 0.0-1.4 stiff, with fine to medium -grained sand. 2.5-3.5 --Organic materials noted to 0.3 foot bgs. --Plow zone encountered throughout. Sandy Silt (ML): Brown, dry, very stiff to 1.4-5.0 hard, with fine to medium -grained sand. Bulk 1.5-2.0 R- --Intermittent weak calcium carbonate Value cementation noted throughout. Silty Gravel with Sand (GM): Light brown to brown, dry, dense to very dense, with fine to 5.0-7.2 coarse-grained sand and 6 -inch minus cobbles. --Intermittent weak calcium carbonate cementation throughout. Poorly Graded Gravel with Sand (GP): Tan to gray, dry, medium dense to dense, with 7.2-11.9 medium to coarse-grained sand and 12 -inch - minus cobbles. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mtiCa)mti-id.com Copyright 02019 Testing g&Inspection MATERIALS TESTING 6 INSPECTION 18 November 2019 Page # 15 of 20 b191879g_limitedgeo AN ATLAS COMPANY ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP -3 Date Advanced: 5 Nov 2019 Logged by: Nick Stevens, G.I.T. Excavated by: Creighton Contracting, LLC Location: See Site Map Plates Latitude: 43.65775 Longitude: -116.37736 Depth to Water Table: Not Encountered Total Depth: 10.9 Feet bgs Depth Field Description and USCS Soil and Sample Sample Depth QP Lab (Feet bgs) Sediment Classification Type (Feet bgs) Test ID Silt with Sand (ML): Brown to dark brown, dry, stiff to very stiff, with fine to medium - 0.0 -1.5 grained sand. 2.0-3.25 --Organic materials noted to 0.5 foot bgs. --Plow zone encountered throughout. Sandy Silt (ML): Brown, dry, hard, with fine to medium -grained sand. 1.5-5.7 --Intermittent weak calcium carbonate 4.5+ cementation noted from 1.5 to 4.1 feet bgs. --Moderate calcium carbonate cementation noted,from 4.1 to 5.7 feet bgs. Silty Gravel with Sand (GM): Light brown to brown, day, very dense, with fine to coarse - 5.7 -7.7 grained sand and 10 -inch minus cobbles. --Moderate to strong calcium carbonate cementation noted from 5.7 to 6.2 feet bgs. Poorly Graded Gravel with Sand (GP): Tan 7.7-10.9 to gray, dry, medium dense to dense, with medium to coarse-grained sand and 15 -inch - minus boulders. 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mti(a)mti-id.com CopyrigTeestingsting Materials ( &Inspection MATERIALS TESTING S INSPECTION 18 November 2019 Page # 16 of 20 b 191879g_limitedgeo AN ATLAS COMPANY ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP -4 Date Advanced: 5 Nov 2019 Logged by: Nick Stevens, G.I.T. Excavated by: Creighton Contracting, LLC Location: See Site Map Plates Latitude: 43.65811 Longitude: -116.37603 Depth to Water Table: Not Encountered Total Depth: 12.3 Feet bgs Notes: Infiltration testing conducted at 12.3 feet bgs. Depth Field DescriptionUSCS oil and Sample Sample Depth Qp Lab s Sediment Classification ification Feet bgs) Test ID Sandy Silt (ML): Brown, dry, stiff to hard, with fine to medium -grained sand. 0.0-6.1 --Organic materials noted to 0.2 foot bgs. GS 0.5-1.0 2.0-4.5+ A --Weak to moderate calcium carbonate cementation noted throughout. Silty Gravel with Sand (GM): Light brown to brown, dry, very dense, with fine to coarse - 6.1 -7.2 grained sand and 8 -inch minus cobbles. --Weak to moderate calcium carbonate cementation noted throughout. Poorly Graded Gravel with Sand (GP): Tan 7.2-12.3 to gray, dry, medium dense to dense, with medium to coarse-grained sand and 13 -inch - minus boulders. Lab Test ID MLL PI Sieve Analysis % passing) % - - #4 #10 #40 #100 #200 A 15.6 NP NP 100 99 82 74.8 65.8 2791 S Victory View Way - Boise, ID 83709 - (208) 376-4748 - Fax (208) 322-6515 www.mti-id.com - mti(a)mti-id.com Copyrightm g Materials Testing 8Inspection MATERIALS 18 November 2019 TESTING & Page # 17 of 20 INSPECTION b191879g_limitedgeo AN ATLAS COMPANY ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections GRAVEL EQUIVALENT METHOD — PAVEMENT THICKNESS DESIGN PROCEDURES Pavement Section Design Location: The Cottages at Serenity Gardens, Residential Roadways Average Daily Traffic Count: Design Life: Traffic Index: Climate Factor: Subgrade CBR Value: R -Value of Aggregate Base: R -Value of Granular Borroir. Subgrade R -Value: Expansion Pressure ofSubgrade: Unit Weight of Base Materials: Total Design Life 18 kipLSAUs: ASPHALTIC CONCRETE: Gravel Equivalent, Calculated: Thickness: Gravel Equivalent, ACTUAL: CRUSHED AGGREGATE BASE Gravel Equivalent (Ballast): Thickness: Gravel Equivalent, ACTUAL: SUBBASE, Gravel Equivalent (Ballast): Thickness: Gravel Equivalent, ACTUAL: TOTAL Thickness: Thickness Required by L\p. Pressure: 400 All Lanes & Both Directions 20 Years 6.00 1 16 80 60 43 0.29 130 33,131 0.384 0.196923077 0.41 0.768 0.329 0.773 1.094 0.321 1.273 1.042 0.321 Design Depth Inches Asphaltic Concrete (at least 2.5): 2.50 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 Subbase (at least 4.2): 6.00 ACHD Substitution Ratios R -Value of Subgrade: 43.00 Subgrade Mr: 24,000 1.95 1.10 1.00 Use = 2.5 Inches Use = 4 Inches Use = 6 Inches 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 Copyright O 2019 Materials www.mti-id.com • mti(a)mti-id.com Testing&Inspection MATERIALS TESTING £s INSPECTION AN ATLAS COMPANY 18 November 2019 Page # 18 of 20 It191879g_limitedgeo ❑ Environmental Services ❑ Geotechnical Engineering ❑ Construction Materials Testing ❑ Special Inspections R -VALUE LABORATORY TEST DATA Source and Description: TP 2: 1.5-2.0; Silt with Sand Date Obtained: 5 November 2019 Sample ID: 19-7959 Sampling and Pre aration: ASTM D75: Moisture Content (%) AASHTO T2: X ASTM D421: Expansion Pressure (psi) AASHTO T87: X Test Standard: ASTM D2844: 390 AASHTO T190: 88 Idaho T8: X 44 Sample A B C Dry Density (Ib/ft) 101.6 101.3 101.0 Moisture Content (%) 19.1 19.7 20.4 Expansion Pressure (psi) 0.63 0.30 0.15 Exudation Pressure (psi) 390 221 88 R -Value 52 44 36 R -Value @ 200 psi Exudation Pressure = 43 2791 S Victory View Way • Boise, ID 83709 • (208) 376-4748 • Fax (208) 322-6515 www.mti-id.com • mtiOmti-id.com CopyrigTeestingsting Inspection