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HomeMy WebLinkAboutRaising Angles Geotechnical Report TAB 3 GEOTECHNICAL REPORT i t '...ice -r al'a 0144-9r.47,croo4 4ke>c-�r01..rid up August 14, 2013 File: BO13395A Alicia Parker, LEED AP Engineered Structures, Inc. 3330 E. Louise Drive, Suite 300 Meridian, Idaho 83642 RE: Geotechnical Engineering Evaluation Raisin Angels Daycare Pine Avenue and Nola Road Meridian, Idaho Dear Alicia: Strata, A Professional Services Corporation (STRATA) is pleased to present our authorized Geotechnical Engineering Evaluation for the proposed Raisin Angels Daycare planned in Meridian, Idaho. Our Geotechnical Engineering Evaluation's purpose was to explore the subsurface conditions in the proposed development area and provide geotechnical recommendations to assist project planning, design and construction. The attached report summarizes our field and laboratory test results and presents our geotechnical engineering opinions and recommendations. The project design, owner, and construction team must read, understand and implement this report in its entirety. Portions of the report cannot be relied upon individually without the supporting text of remaining sections, appendices and plates. We recommend STRATA be retained to provide monitoring, testing, and consultation services to verify our report recommendations are being followed. We appreciate the opportunity to continue our professional relationship with Engineered Structures Inc., and the project design and construction teams. We look forward to our continued involvement on this project throughout construction. Please do not hesitate to contact us if you have any questions or comments. e4 , �kQ p� STt�fi ' ;,TRATA 1 Q. tri `/f/3 ,; {chael oodwort� P.E. +� ngineering Manager 4 Adrian Mascorro, P.E. Project Engineer MGW/AM/nm www.stratageotech.com REPORT Geotechnical Engineering Evaluation Raisin Angels Daycare Pine Avenue and Nola Road :eridinan, Idaho epared For: arker, LEED AP Eed Structures, Inc. 33ouise Dr., Ste. 300 ian, ID 83642 ENGINEERED STRUCTURES INC. Prepared By: STRATA, Inc. 8653 W. Hackamore Dr. Boise, Idaho 83709 P. 208.376.8200 F. 208.376.8201 August 14, 2013 TABLE OF CONTENTS Page INTRODUCTION 1 PROJECT UNDERSTANDING 2 SUBSURFACE EVALUATION PROCEDURES 3 SUBSURFACE CONDITIONS 3 LABORATORY TESTING 4 GEOTECHNICAL OPINIONS AND RECOMMENDATIONS 4 Earthwork 5 Excavation Characteristics 5 Site Preparation 5 Wet Weather/Soil Construction 6 Utility Trench Construction 6 Structural Fill and Compaction 7 Table 1. Structural Fill Specifications and Allowable Use 7 Geosynthetics 8 Foundation Design 9 General 9 Bearing Soil 9 Design Criteria 9 Seismicity 10 Concrete Slab-on-Grade Floors 10 Site Drainage 11 Stormwater Disposal 11 Exterior Grading 12 Pavement Subgrade Preparation and Section Design 12 General 12 Traffic and Subgrade 12 Table 2. Pavement Design Parameters 12 Asphalt, Aggregate Base Course and Subbase Materials 13 Pavement Section Thickness 13 Table 3. Asphalt Pavement Design Section 14 Pavement Maintenance 14 GEOTECHNICAL DESIGN CONTINUITY 14 EVALUATION LIMITATIONS 15 8653 West Hackamore Drive,Boise,Idaho 83709 Phone,208.376.8200 Fax.208.376.8201 www.stratageotech.com Geotechnical Engineering Evaluation Raisin Angels Daycare Pine Avenue and Nola Road Meridian, Idaho INTRODUCTION Strata, A Professional Services Corporation (STRATA) is pleased to provide our Geotechnical Engineering Evaluation for the proposed daycare facility planned in Meridian, Idaho. Our Geotechnical Engineering Evaluation's purpose was to explore the subsurface soil conditions at the project site and to prepare geotechnical recommendations to assist project planning, design and construction. We accomplished our services referencing our authorized geotechnical Proposal dated August 1, 2013. To accomplish our evaluation, STRATA performed the following services: 1. Coordinated exploration with the Digline Utility Notification Center to help reduce the potential for damage to existing utilities. 2. Observed 2 test pits in the proposed development area. Our field geologist visually described, classified and logged soil encountered referencing the Unified Soil Classification System (USCS). 3. Accomplished one field infiltration test to evaluate the infiltration characteristics of gravel alluvium. We also correlated grain size distribution laboratory test results to regional stormwater correlations to help identify the potential stormwater disposal methods. 4. Performed laboratory tests with reference to ASTM International (ASTM) procedures including Atterberg limits, in-situ moisture and grain size evaluation. 5. Performed engineering analyses in order to provide geotechnical design and earthwork construction recommendations. Our engineering analyses provides geotechnical recommendations for: 6 Earthwork • Excavation characteristics • Site preparation • Wet weather/soil construction • Structural fill • Utility trench construction • Geosynthetics 6 Foundation Design • Bearing soil • Design criteria • Seismicity 6 Concrete Slabs-on-Grade • Minimum support section • Vapor retarders www.stratageotech.com • Raisin Angels Daycare File: B013393A Page 2 6 Site Drainage • Stormwater disposal • Exterior grading • Foundation drainage �a Asphalt Pavement • Subgrade preparation requirements • Design parameters • Section design 6 Geotechnical Design Continuity • Plan and specification review • Geotechnical design confirmation • Construction observation and testing 6. Prepared and provided an electronic report of geotechnical findings and opinions, including exploration logs and laboratory test results. Hard copies are available upon request. PROJECT UNDERSTANDING The project site occupies approximately 0.94 acres of relatively flat terrain southwest of the intersection of Nola Road and Pine Avenue in Meridian, Idaho. Existing site conditions at the time of our exploration are shown in the site photograph below: Photograph 1: Site conditions facing southeast. We understand the project will consist of design and construction of an approximate 5,500-square-foot, single-story, wood-frame structure. We anticipate the building will be supported by conventional shallow foundations with a concrete slab-on-grade floor. Asphalt www.stratageotech.com Raisin Angels Daycare File: B013393A Page 3 paving will provide access and parking areas and stormwater will be retained and disposed of on-site. Based on our experience with similar projects, we anticipate foundation loads will be less than approximately 2 kips per lineal foot for wall loads, with column loads of up to approximately 25 kips. Traffic loading is anticipated to consist primarily of passenger vehicles with very occasional truck traffic. SUBSURFACE EVALUATION PROCEDURES STRATA accomplished subsurface exploration on August 6, 2013 via 2 exploratory test pits extending up to 13 feet below existing ground surface. The approximate exploration locations are illustrated on Plate 1, Exploration Location Plan, which also delineates the proposed development. Test pit locations were established in the field by taping from existing site features. A professional geologist visually evaluated the soil encountered in each test pit and logged the soil profile referencing the USCS. We provide a brief USCS explanation in Appendix A to help interpret the terms on individual test pit logs. Individual test pit logs are also provided in Appendix A. The test pits were backfilled with the excavated material to the ground surface following the completion of excavations. We performed in-situ infiltration testing to assist in evaluating stormwater disposal infiltration rates. STRATA performed infiltration testing in TP-2 at a depth of 8 feet. We accomplished infiltration testing referencing the Idaho Department of Environmental Quality Technical Guidance Manual infiltration test method. SUBSURFACE CONDITIONS We observed topsoil and vegetation to a depth of approximately 6 inches below-grade within the test pits. Soil conditions encountered within test pits generally consist of silty sand and gravel fill overlying native silt and lean clay, with poorly-graded gravel with sand alluvium at depth. The poorly-graded gravel with sand was encountered to the bottom of the test pits. We provide more specific discussion of each soil unit encountered below: 6 Silty sand fill — We encountered tan to brown, dense, moist silty sand and silty gravel fill at the ground surface across the site. The fill soil was noted to be relatively consistent across the site, and extended to a depth of approximately 2 feet in both test pit excavations. www.stratageotech.com • Raisin Angels Daycare File: B013393A Page 4 6 Native silt and lean clay — Native silt and lean clay is present underlying surficial fill in both test pit excavations. Silt and lean clay is brown, hard and moist with calcium carbonate cementation observed within the silt soil. Silt and clay soil extends to approximately 4 to 6 feet in the test pit excavations. 6 Poorly-graded gravel with sand — Below silt and clay soil, we observed poorly-graded gravel with sand to the test pit termination depths of up to 13 feet. The gravel with sand and silt was described as tan, dense and moist. Specific soil contacts and descriptions are further described on individual test pit logs provided as Appendix A to this report, along with a USCS explanation to assist with test pit log information. We did not encounter groundwater within test pits at the time of exploration. LABORATORY TESTING We returned soil samples collected in the field to our laboratory for further classification and testing and accomplished laboratory testing referencing ASTM International procedures. We developed our laboratory testing program for this project primarily to verify soil classification through index testing, as well as to evaluate settlement characteristics of fine grained soil. Specifically, we accomplished the following laboratory testing: 6 In-situ moisture content 6 Grain size analysis 6 Atterberg Limits We present index laboratory test results on test pit logs in Appendix A and the laboratory testing summary is presented as Appendix B. We will retain soil samples for 90 days and discard after this time period unless we are notified to store the samples for an extended period of time. GEOTECHNICAL OPINIONS AND RECOMMENDATIONS We present the following geotechnical recommendations to assist planning, design and construction of the proposed Raisin Angels Daycare planned southwest of the intersection of Pine Avenue and Nola Road in Meridian, Idaho as illustrated on Plate 1 attached to this report. This report also provides specific foundation and other geotechnical design criteria for the development which the structural and civil design and construction teams must review to verify the applicability to the planned structure. We base our recommendations on the results of our field evaluation, laboratory testing, our experience with similar soil conditions and our www.stratageotech.com • Raisin Angels Daycare • File: B013393A Page 5 understanding of the proposed construction. If design plans change or if the subsurface conditions encountered during construction vary from those observed during our field evaluation, we must be notified to review the report recommendations and make necessary revisions. Earthwork Excavation Characteristics Based on exploration results, near-surface soil encountered in exploratory test pits can be excavated with conventional equipment. Excavations can cave and slough and must be sloped back in accordance with Occupational Health and Safety Act(OSHA) guidelines. Fine to coarse-grained soil is expected to be exposed in excavations throughout the development area and should be temporarily sloped at 1.5H:1 V (horizontal to vertical). Due to the potential for varying soil conditions at the time of construction, we recommend earthwork contractors evaluate each excavation configuration specific to OSHA guidelines and to seek appropriate professional guidance to ensure excavation safety and stability. Site Preparation STRATA has not reviewed a grading plan for the project, but we anticipate cut and fill will be less than approximately 1 to 2 feet for project site grading. At the time of exploration, surficial vegetation and organic material was observed to a depth of approximately 6 inches. We recommend a minimum of 6 inches of topsoil with organic matter be stripped beneath all planned improvements, including structural fill areas. This topsoil is not suitable for use as structural fill and should be wasted or stockpiled on-site for landscape areas. Test pits have been marked in the field with labeled stakes or a standpipe piezometer. Test pit locations should be surveyed prior to any earthwork site grading activities. Test pits which are located beneath paving, structural fill or building lot areas should be re-excavated and replaced with structural fill in accordance with the recommendations in this report. We encountered silty gravel fill at the ground surface in each test pit location. Undocumented fill has the potential to settle below new foundations and pavements and such settlement could negatively impact their performance. Undocumented fill must be removed below planned foundations as discussed in the Foundation Design report section. Additionally, we estimate 1 to 1.5 feet of fill may remain below some of the pavement and slab areas. For this reason, we provide the following recommendations for site preparation: Excavate the exposed subgrade to the project design elevations and tolerances. www.stratageotech.com Raisin Angels Daycare File: 6013393A Page 6 6 Scarify and moisture-condition the finished subgrade below slabs and pavement areas to within 3 percent of optimum moisture content to at least 8 inches prior to compaction effort. Moisture-conditioning may include aeration or adding moisture. • All existing fill must be removed below foundation areas. • To improve support characteristics, compact subgrade soil to at least 92 percent of ASTM D1557 (Modified Proctor). • Foundation subgrade soil at the base of proposed soil improvements will not require compaction and moisture conditioning. Earthwork contractors must expect substantial moisture-conditioning and compaction efforts to achieve proper subgrade moisture. If the subgrade is wet at the time of construction and compaction and moisture-conditioning is not practical, STRATA should be contacted to evaluate the use of a woven geotextile, as discussed in this report's Geosynthetics section. Wet Weather/Soil Construction We strongly recommend earthwork construction take place during dry weather conditions. While the near-surface is typically granular, the soil contains sufficient fines to be susceptible to pumping or rutting from heavy loads such as rubber-tired equipment or vehicles when the soil is above optimum moisture content. Earthwork should not be performed immediately after rainfall or until soil can dry sufficiently to allow construction traffic without disturbing the subgrade. During and after achieving subgrade elevation, the contractor must take precautions to protect the subgrade from becoming disturbed or saturated. We recommend the contractor limit construction traffic to any prepared subgrade and reduce exposure to precipitation and water. Utility Trench Construction Structural fill for backfilling utility trenches and all bedding should conform to Idaho Standards for Public Works Construction (ISPWC) specifications, except that all trench backfill must be placed and compacted to the structural fill requirements presented herein. Loose soil must be removed from the base of utility trenches prior to placing pipe bedding. In addition, if water is encountered, it must be removed from the base of the utility trench before placing pipe bedding. We recommend utility pipes be placed on at least 4 inches of bedding placed over undisturbed native soil, structural fill or otherwise supported according to the pipe manufacturer's specifications and ISPWC requirements. After bedding the pipe, place structural fill and compact it from the pipe invert to 1-foot above the top of the pipe with tamping bars and/or plate compactors to render the backfill in a firm www.stratageotech.com Raisin Angels Daycare File: B013393A Page 7 and unyielding condition. Thoroughly place and compact bedding below pipe haunches or the zone between the pipe invert and the spring line. To accomplish backfilling, the distance between the side of the pipe at the spring line and the trench wall should be at least 12 inches. The remainder of the utility trench should be backfilled in accordance with the Structural Fill and Compaction section of this report. Structural Fill and Compaction All fill placed for the development must be placed as structural fill. The structural fill requirements described in Table 1, in general, correlate to ISPWC material specifications. Project structural fill products are described in Table 1 below. Table 1. Structural Fill Specifications and Allowable Use ',4 ua • Soil classified as GP, GW, GM, SP, SW, SM or General Structural Fill ML according to the USCS. General site grading • Maximum particle size must be less than 6 inches. • • Soil consisting of inert earth materials with< 3 percent organics or other deleterious substances wood, metal, •lastic, waste, etc . Granular Structural Fill • Soil classified as GP, GP-GM, GW, according to 6 Inch 100 General site grading • the USCS, and meeting the gradation provided. 3 Inch 90-100 • Over-excavation Soil meeting requirements stated in the latest No. 4 30-60 • Pavement section• edition of the Idaho Standard for Public Works No. 200 <10 granular subbase Construction(ISPWC), Section 801-Aggregate Subbase. • Soil meeting requirements stated in the latest 1 Inch 100 edition of the Idaho Standard for Public Works Inch 80-100 Utility Trench Bedding Construction(ISPWC), Section 305-Pipe '3/8 Inch 20-70 Bedding. No. 4 5-20 • Soil may not contain particles larger than 1 inch in No. 8 0-5 median diameter and must meet the required No. 200 0-3 •radation. • Soil meeting requirements stated in the latest 1 Inch 100 Aggregate Base Course edition of the Idaho Standard for Public Works • Over-excavations Construction(ISPWC), Section 802-Aggregate '/Inch 90-100 • Granular structural fill Base. No. 4 40-65 • Pavement section • Soil may not contain particles larger than 1 inch in No. 8 30-50 base course median diameter and must meet the required No. 200 3-9 •radation. All structural fill from on-site or imported sources should be placed in maximum 10-inch- thick lifts, and each lift shall be moisture-conditioned to within 3 percent of optimum moisture content and compacted to a minimum of 95 percent of ASTM D 1557 Modified Proctor. The maximum, loose-lift thickness is based on using large, 5- to 10-ton, smooth-drum vibratory www.stratageotech.com Raisin Angels Daycare File: BO13393A Page 8 rollers. The maximum loose lift thickness should be reduced where smaller and/or lighter compaction equipment is used. STRATA should be retained to perform field density testing of structural fill to verify contractor compliance with the above minimum compaction criteria. Structural fill with greater than 30 percent retained above the 3h-inch sieve is too coarse for proctor density testing, but may be used as granular structural fill provided it meets the above specification. Coarse fill must be compacted using a "method specification" developed during construction, based on the material characteristics and the contractor's means and methods. It is common that "method specifications" are developed during construction, specific to the materials and conditions encountered. At a minimum, STRATA recommends coarse, granular fill be placed in maximum 10-inch lifts and compacted with 6 complete passes of a 10- ton vibratory or grid roller. Vibratory rollers must have a dynamic force of at least 30,000 pounds per impact per vibration and at least 1,000 vibrations per minute. Coarse fill must be compacted to a dense, interlocking and unyielding surface. We recommend STRATA review the soil and aggregate material planned for fill use and monitor compaction effort during construction. Geosynthetics If earthwork contractors are unable to achieve subgrade compaction requirements outlined in this report's Site Preparation section, geosynthetic fabrics may be used to improve subgrade support when constructing on soft or wet soil. We recommend woven geosynthetics at pavement subgrade elevation where moisture-conditioning and re-compaction as recommended in the Site Preparation section of this report is not possible due to wet soil conditions. Where required, apply geosynthetics directly on approved subgrade, taut, free of wrinkles and over-lapped at least 12 inches. Woven geosynthetic fabrics for subgrade stabilization and soil improvements shall have the following minimum properties of 700 pounds (CBR Puncture, ASTM D6241) and 200 pounds (Grab Tensile Strength ASTM D4632). STRATA must be consulted prior to using geosynthetics for subgrade stabilization. We recommend non-woven geosynthetic fabrics for filtration and for stormwater facilities. Non-woven fabrics and should have a maximum apparent opening size equivalent to the U.S. No. 70 sieve (ASTM D4751), a minimum weight of 3.5 ounces per square yard and minimum CBR puncture resistance of 200 pounds (ASTM D6241). www.stratageotech.com Raisin Angels Daycare File: B013393A Page 9 Foundation Design General We recommend STRATA be retained to observe the foundation system installation prior to placing concrete forms or concrete. Reviewing the final foundation bearing surfaces helps confirm our allowable bearing pressures and settlement estimates and is an important part of the geotechnical design process. Exterior footings must extend at least 24 inches below the final exterior ground surface to help protect against frost action. Interior foundations must extend at least 18 inches below final slab-bearing elevations and maintain at least 4 inches of gravel between slabs and the top of the footing to reduce the reflective cracking potential. Foundations must be structurally designed to conform to the latest edition of the International Building Code (IBC). The foundation bearing pressures presented below can be increased 30 percent to account for transitory live loads such as seismic and wind. Our analysis utilizes a factor of safety against bearing capacity failure of 3.0 or greater. Settlement estimates and other design criteria are unfactored. Based on the assumed foundation loading conditions, the text below provides recommended design and construction criteria. Bearing Soil From exploration, we expect the foundation excavations will expose native clay, silt or undocumented fill. Any undocumented fill exposed on foundation excavations must be completely removed to expose underlying hard lean clay or silt soil. Foundations shall bear on native lean clay, silt or structural fill placed over native soil. Design Criteria Foundations constructed on granular soil improvements as presented in this report may be designed using a maximum allowable bearing pressure of 2,000 pounds per square foot (psf). Mass concrete placed on soil improvements over compacted subgrades can utilize a friction coefficient Os) of 0.35 to resist lateral loads. This coefficient must be reduced by 1/3 if concrete is not cast directly on soil such as for pre-cast panels. Using good construction practices and constructing during good weather, we estimate foundations bearing on subgrades prepared as recommended herein will realize 1 inch total and 0.5 inches of differential settlement in a 30-foot span. Our settlement estimates rely on 12- inch-wide minimum continuous foundations. Foundation dimensions less than these should be www.stratagedtech.com Raisin Angels Daycare File: BO13393A Page 10 analyzed for changes in settlement potential. Where water accumulates at the foundation elevation, settlement can be in excess of our estimates and the building tolerances. Therefore, we recommend exterior grading provide adequate drainage away from the building. Seismicity We expect the 2009 IBC will be utilized for project structural design. IBC Section 1613 outlines the procedure for evaluating site ground motions and design spectral response accelerations. STRATA utilized site soil and geologic data and the project location to establish earthquake-loading criteria at the site referencing IBC Section 1613. Based on our field exploration and knowledge of the upper 100 feet of the soil profile, we recommend a Site Class D be utilized as a basis for structural seismic design. Concrete Slab-on-Grade Floors Concrete slab-on-grade floors should be supported by compacted crushed aggregate base course placed on a prepared subgrade, as described in this report's Site Preparation section. We recommend concrete slab-on-grade floors exposed to typical pedestrian and light storage loads be underlain by at least 4 inches of crushed aggregate base course to provide a leveling course and capillary break for the slab. Subgrade areas that become soft, wet or disturbed or that cannot be recompacted to structural fill requirements must be over-excavated to firm soil and replaced with granular structural fill prior to placing aggregate base. Interior floor slabs may be susceptible to moisture migration caused by capillary action and vapor pressure. Floor coverings such as tile, vinyl, or other "impervious coatings" may exist and a vapor retarder is strongly encouraged in these areas. Where utilized, vapor retarders must consist of a thick, 15-mil, puncture-resistant sheeting consistent with American Concrete Institute (ACI) Section 302.2R-06 specifications. An example of a common vapor retarder is Stego WrapTM, a 15-mil vapor retarder. The specific location of vapor retarders has been widely discussed in the architectural, structural, construction and geotechnical engineering community, and differing opinions exist. However, current recommendations by the ACI recommend placement of a vapor retarder directly below the concrete slab. However, ultimately, the location of the vapor retarder (if a vapor retarder is specified) should be carefully considered by the owner and architect. Studies have shown that decreased concrete water-cement ratios, higher strength concrete, and good construction finishing practices significantly decrease any negative impacts associated with www.stratageotech.com • Raisin Angels Daycare File: B013393A Page 11 both of the above options for vapor retarder locations. Installation of form stakes or other sub-slab penetrations must never be allowed to puncture the vapor retarder. Manufacturer recommendations for proper sealing of slab-to-wall connections, plumbing or other penetrations must be strictly followed. Although these recommendations are used, water vapor migration through the concrete floor slab is still possible. Floor covering must be selected accordingly and manufacturer's recommendations strictly followed. Exterior slabs are susceptible to frost action which can generate substantial frost heave at certain times of the year. The potential for frost heave may not be acceptable at entries or other critical areas adjacent to the building that will be exposed to weather. One approach to provide partial frost protection requires removing 65 percent of material within the frost depth and replacing it with granular structural fill. If this method is employed, the over-excavated soil must be replaced with aggregate base course as specified in the Structural Fill section. Alternatively, if partial frost protection is unacceptable, over-excavation and aggregate base course replacement must be accomplished to the anticipated frost depth (24 inches). Site Drainage Stormwater Disposal We performed infiltration testing within native, poorly graded gravel encountered at depth across the site. We measured an infiltration rate of approximately 20 inches per hour during testing. Considering the relatively permeable gravel soil, we recommend all infiltration facilities extend a minimum of 1-foot into native, poorly graded gravel soil. Approximate excavation depths of 4 to 6 feet below-grade should be anticipated to expose native gravel. We recommend all subsurface infiltration facilities that extend into poorly graded gravel with silt be designed using a design infiltration rate of 8 inches per hour. We did not encounter groundwater at the time of exploration. Groundwater in the site vicinity is primarily related to irrigation in the site vicinity and canal leakage. Based on our experience in the area, we anticipate seasonal high groundwater will typically be observed in later summer. Therefore, we recommend civil design for infiltration facilities assume seasonal high groundwater occurs at a depth of approximately 13 feet below existing grade. www.stratageotech.com Raisin Angels Daycare . File: B013393A Page 12 Exterior Grading We recommend the ground surface outside of any structure be sloped a minimum of 5 percent away for 10 feet to rapidly convey surface water or roof runoff away from foundations. Remaining landscapes should slope at least 2 percent away from structures. Roof downspouts should be provided and connected to a solid pipe placed away from structures and not allowed to infiltrate into the soil underlying the structure. Stormwater should be routed away from disturbed soil areas and should be disposed of in stormwater disposal facilities located at least 20 feet from the proposed building. Pavement Subgrade Preparation and Section Design General The following flexible asphalt pavement section design is provided referencing the American Association of State Highway and Transportation Officials (AASHTO) Guide for Design of Pavement Structures (1993). STRATA estimated traffic loading and design parameters based on our proposed construction and traffic understanding, results from laboratory testing and our understanding of the subsurface conditions. Traffic and Subgrade The tables continued on the next page present our traffic loading, geotechnical design parameters and references as well as the resulting flexible pavement section design recommendations. Table 2. Pavement Design Parameters Design Parameter Value d :ra-sa.a $ Reliability(R) 90% Estimated Standard Deviation(S) 0.45 AASHTO 1993 Initial Serviceability(PSI;) 4.2 Typical regional values Terminal Serviceability(PSIZ) 2.1 Typical regional values 75,000 ESALS' Traffic Loading (Standard-Duty) Assumed Design Life 20 years Assumed Based on CBR and Mr correlations(see Resilient Modulus(Mr) 6,000 psi2 paragraph below) Asphalt Layer Coefficient(al) 0.42 Figure 2.5 AASHTO 1993 Top Course Layer Coefficient(a2) 0.12 Figure 2.6 AASHTO 1993 Top Course Drainage Coefficient(m2) 1.0 Table 2.4 AASHTO 1993 for"fair drainage, 1 to 8 percent saturation Equivalent Single Axle Loads(ESALs). 2Pounds per square inch(psi). www.stratageotech.com • Raisin Angels Daycare File: B013393A Page 13 From correlations to index laboratory testing, we estimate the silt and clay subgrade for proposed asphalt areas will have a CBR value of 5 or less and a resilient modulus (Mr) correlation of 6,000 pounds per square inch. To help improve subgrade characteristics, the pavement subgrade should be prepared as recommended in this report's Site Preparation section. Subgrades must be shaped (crowned) and graded to facilitate positive drainage and inverted crowns must be avoided. Asphalt, Aggregate Base Course and Subbase Materials Crushed aggregate base course and granular subbase shall conform to the Structural Fill requirements section, and be placed directly over a properly prepared subgrade. We recommend STRATA observe final subgrade preparations, geotextile placement and all aggregate placements. Asphalt concrete must be compacted to 92 percent of the maximum density for a Hveem or Superpave mix design. If subgrade conditions appear significantly different during construction, traffic loading conditions change or traffic volumes increase, STRATA should be notified to amend our design accordingly. Pavement Section Thickness STRATA evaluated the pavement sections utilizing the AASHTO pavement design methodology, soil-engineering parameters from previous field and laboratory testing and the estimated traffic-loading conditions. Based on subgrades prepared as recommended, and the traffic criteria provided, Table 3 provides the recommended asphalt section for the anticipated pavement application. If traffic loading or subgrade conditions change as design is finalized or during construction, STRATA must review our pavement analyses and resulting sections. For clarity, access drives are primary routes into the site where truck, fire vehicles or other heavy traffic is expected. www.stratageotech.com • Raisin Angels Daycare File: B013393A Page 14 Table 3. Asphalt Pavement Design Section po_ r RLL 1 dk' Standard Dut Section —Parkins 2.5 4 10 Pavement Maintenance We recommend crack maintenance be accomplished on all pavement surfaces every 3 to 5 years to reduce the potential for surface water infiltration into the underlying pavement subgrade. Surface and subgrade drainage are extremely important to the performance of the pavement section. Therefore, we recommend the subgrade, base and asphalt surfaces slope at no less than 2 percent to an appropriate stormwater disposal system or other appropriate location that does not impact adjacent buildings or properties. Ponding water at the pavement subgrade surface can induce heaving during the freeze-thaw process. GEOTECHNICAL DESIGN CONTINUITY Geotechnical design continuity will be an important aspect of this project's successful completion. In our opinion, geotechnical continuity can occur in 3 stages in the planning, design and construction project aspects. Specifically, we recommend STRATA maintain the geotechnical design continuity in the following aspects: 0 Plan and Specification Review: We recommend STRATA be retained to review final design and construction plans and specifications to verify our geotechnical recommendations are incorporated into project bidding and construction documents as well as to provide additional recommendations based on the final design concepts. These efforts can provide document continuity across the engineering disciplines and reduce the potential for errors as the project concepts evolve. 0 Geotechnical Design Confirmation: The potential site soil variation may have a significant impact on foundation and slab construction. As such, we recommend STRATA be retained to provide geotechnical engineering oversight during foundation installation to observe the potential variability in the soil conditions and provide consultation regarding potential impacts on foundation construction. STRATA can also provide construction material testing and special inspection for concrete, masonry, reinforcement, and asphalt. If we are not retained to perform the recommended services, we cannot be responsible for related construction errors or omissions. www.stratageotech.com Raisin Angels Daycare File: B013393A Page 15 EVALUATION LIMITATIONS This report has been prepared to assist project planning design and construction of the proposed Raisin Angels Daycare in Meridian, Idaho. Our geotechnical findings and opinions have been developed based on the authorized subsurface exploration and laboratory testing, as well as our understanding of the project at this time. Our geotechnical design recommendations are specific to the planned building design and infrastructure construction and should not be extrapolated to other future site developments without allowing adequate geotechnical consultation by STRATA. Subsurface variations may exist between exploration locations and may not be apparent until construction. Test pits only allow us to observe a portion of the site subsurface conditions. Where such variations exist, they may impact opinions and recommendations presented in this report, as well as construction timing and costs. Our services consist of professional opinions and findings made in accordance with generally accepted geotechnical engineering principles and practices in southwest Idaho at the time of this report. The geotechnical recommendations provided herein are based on the premise that appropriate geotechnical consultation during subsequent design phases is implemented and an adequate program of tests and observations will be conducted by STRATA during construction to verify compliance with our recommendations and to confirm conditions between exploration locations. This acknowledgment is in lieu of all warranties either express or implied. The following plates and appendices accompany and complete this report: Plate 1: Exploration Location Plan Appendix A: Unified Soil Classification System (USCS) & Exploratory Test Pit Logs Appendix B: Laboratory Test Results www.stratageotech.com • . :mss z g o H O L Og O U i F W I..o N WENN ) Ove Z 2 ~ . .L } Z ,ala OJ' W - ¢ H ^32 w N C W 4a g uE W E co d �. K x�--' � 0 0 W na < W - .2-. XI NOLA ROAD • 1 I n0 H 1 LI i I 1 ®i 1 i Z 1 1 I W Z I G ` 1 1 1 1 Psi 01 1 1 u I I I ill II vi �� I Hi ll I 116 1hi 1 0 o I1iii L .gb 23 -------------------- -----------J ' 111 I.. al IP 5 et a. NI a. ot IIS E& W K APPENDIX A • UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GRAPH LETTER TYPICAL NAMES SYMBOL SYMBOL li•:Q•:.... • GW Well—Graded Gravel, _p CLEAN :"0.....c Gravel—Sand Mixtures. GRAVELSGP Poorly—Graded Gravel, O Gravel—Sand Mixtures. GRAVELS :$:1 �, GM Silty Gravel, Gravel— GRAVELS , Sand—Silt Mixtures. WITH ,•� `' Clayey Gravel, Gravel— COARSE FINES GC Sand—Clay Mixtures. GRAINED Well—Graded Sand, SOILS CLEAN SW Gravelly Sand. SANDS Poorly—Graded Sand, SP Gravelly Sand. SANDS .• .• .1 SM Silty Sand, SANITDS ' •' i 1• Sand—Silt Mixtures. WH FINES ��;• •• SC Clayey Sand, Sand—Clay Mixtures. rML Inorganic Silt, Sandy or Clayey Silt. SILTS AND CLAYS Inorganic Clay of Low LIQUID LIMIT CL to Medium Plasticity, LESS THAN 50% Sandy or Silty Clay. Organic Silt and Clay ill , 1 I I OL of Low Plasticity. FINE Inorganic Silt, Mica— GRAINED MH ceous Silt, Plastic SOILS Silt. SILTS AND CLAYS MV CH Inorganic Clay of High Plasticity, Fat Clay. LIQUID LIMIT ,, Organic Clay of Medium GREATER THAN 50% OH to High Plasticity. PT Peat, Muck and Other Highly Organic Soils. BORING LOG SYMBOLS GROUNDWATER SYMBOLS TEST PIT LOG SYMBOLS IStandard 2—Inch OD V Groundwater BG Baggie Sample Split—Spoon Sample — After 24 Hours ' - California Modified 3—Inch (7-3-07)Indicates Date of BK Bulk Sample OD Split—Spoon Sample — Reading IIRock Core 0 Groundwater RG Ring Sample - Shelby Tube 3—Inch OD _ at Time of Drilling Undisturbed Sample Shorthand Notation: BGS = Below Existing Ground Surface N.E. = None Encountered T R al-a A PROFESSIONAL SERVICES CORPORA LION 1:n f'oc'i-r crows J-!.�E7rou.tS Up • -� o rn d'' lip REMARKS z v)v) a' O m c u, O nG) (j yFl m c� 7.. o-f F-.�. (A m d � - m > N U C USCS Description w 00)-I g E F G 1K= a o°` 0 g o a) Y Note:BGS=Below Ground O �O co Cl) 0 - „.9.z� O 20 d Surface SILTY SAND,With Gravel(fill), = 0.0 • ., '• (SM)brown,dense,moist _ .' "• „ Grass roots to 6 inches • • • BG - SM .T.I▪ •I yI. . ••1•i• • ' a • • _ •1. • SILT,With Sand(native),(ML) 9 brown,hard,moist = Strong cementation between 2 - 2.s to 3 feet BGS ' i ,BG - ML I 1 l _ w POORLY GRAVEL,With = • bv, Sand,(GP)tan,dense Y .0 Q fl • _ b.3° -5.0 O ci b. .00 c�°. ` Moderate caving between 7 to - GP o pC I 11 feet BGS 0. F .01C. BG - 7.5 0c ii 1 a ,r w •'Q. , < 0 Cy. co 1 C co 0.0. o - .. W - • g•$ 7 = .a o. G. o Qa. , cn o.o' U :0. J � W 10.0 aTest Pit Terminated at 10.0 Feet. Terminated due to caving z 0 L 0 co Co m as 0 c co J Client: ESI Test Pit Number: TP-1 % EXPLORATORY ~ Project: B013393A Date Excavated: 08-06-2013 S 1"Ft TEST PIT LOG x a Backhoe: CASE 580K _ 4 Bucket Width: 2' _ a--_--_ `"'" `'r "'_ Sheet 1 Of 1 Depth to Groundwater: N.E. I Logged By: SW I • IJ J O rn mo = REMARKS m O s Eo m I U� m o.o. w = 2 e > N� — c d USCS Description w x J g m 1- 0 ani N d o o n o.. Ne'. Note:BGS=Below Ground 0 jO CO coI-- 2 0 Z Q MU d Surface SILTY GRAVEL,With Sand(fill), _ t ' • (GM)tan,dense,moist • Grass roots to 6 inches BGS T • • t BG GM •} • ll � • T • 1 ' � • ' — ATTERBERG LIMITS I • 1 LEAN CLAY,(native),(CL)brown, _ `` LL=40 hard,moist \ BG 19.6 PI=16 - 2.5 CL POORLY GRADED GRAVEL,With : Sand And Silt,(GP-GM)brown, : 0 jkop hard,moist - o k *° 111 O j,o'C GP- o b GM r Q 1g, —5.0 o'o'c o ►1 - rQ I a'o'c POORLY GRADED GRAVEL,With a Sand,(GP)tan,dense,moist : I .0 Q fl • .Q. ' od BG3.4 3.3 r - 7.5 0Q2, 1 w _ o b Infiltration test performed at 8 - .C110. feet BGS.Infiltration rate=20 `5o inches per hour measured. M o .D w - a m aC O _ m _ o D:'. g .'0..C. E. - GP iEy coU Li, o Q —10.0 rO' ' cl' _ 9 60 O • . rio..p' )0 'D (3.0.' • 3.7. a >o.'oe co 'Q°• ),.±:; D:.. re -12.5 o Q 0D 0 J .. n.c' J 6fighEitjgrrninated at 13.0 Feet. Test Pit Number: TP-2 EXPLORATORY CL 17 Project: B013393A Date Excavated: 08-06-2013 S T R&T a TEST PIT LOG a Backhoe: CASE 580K Bucket Width: 2' a — — — _ -- Sheet 1 Of 1 1 Depth to Groundwater: N.E. Logged By: SW i APPENDIX B u :TIH*i$i*if j / E E pii 0 ^ \\ �. »: <§ x iiii 01 « % n 2 ` / d _1 » 02 � � 2 m $ Ilk PIC 110 Pil., y; i ll M \ P ea \moo . « kif k 0 a 7 - ; It it" It L. a y "d . :\ o z e 2 � \ tO % \ 7 'rill2± 7 k \ : o = / 1.0 \ 2 ■ IllillIli'/kitijI ff 4 \ i Ai r.1,1 7 4::: „,,,,i,,,,,,ii 7::: :7- g§ fp< \ \k\ § \. m mo _ : ; / lii �1 £Ilk \ iili« t ^ :.0.',$o % E *\ es © « ■ 111 Ct. % � � / \ cZ 7 /\ - ri c' » ; - . \ 4 is or ig v 0 lei .. Of II ! co*iiiiit km r 2 . 0 kk = —\ \ \ asn 7/ \. iii tt \\ 1I1iiiiIIIf CI