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PZ - Geotech Report
Ire S .. „' • V Y I 40 r GEOTECHNICAL INVESTIGATION BINGHAM MULTI-FAMILY 200 East Rosalyn Drive Meridian, ID PREPARED FOR: Mr. Randy Haverfield Architecture Northwest, P.A. 224 16th Avenue South Nampa, ID 83651 PREPARED BY: Atlas Technical Consultants, LLC 2791 South Victory View Way July 8, 2021 Boise, ID 83709 B211698g rrN+M= 'T�� -I July 8, 2021 Atlas No. B211698g Mr. Randy Haverfield Architecture Northwest, P.A. 224 16th Avenue South Nampa, ID 83651 Subject: Geotechnical Investigation Bingham Multi-Family 200 East Rosalyn Drive Meridian, ID Dear Mr. Haverfield: In compliance with your instructions, Atlas has conducted a soils exploration and foundation evaluation for the above referenced development. Fieldwork for this investigation was conducted on June 22, 2021. Data have been analyzed to evaluate pertinent geotechnical conditions. Results of this investigation, together with our recommendations, are to be found in the following report. We have provided a PDF copy for your review and distribution. Often, questions arise concerning soil conditions because of design and construction details that occur on a project. Atlas would be pleased to continue our role as geotechnical engineers during project implementation. If you have any questions, please call us at (208) 376-4748. Respectfully submitted, Bailey Hereford Elizabeth Brown, PE Engineering Technician Geotechnical Services Manager J�Vwp aL Monica Saculles, PE Senior Geotechnical Engineer Distribution: Steve Hill, Hill Construction (PDF Copy); Will Mason, Mason &Associates (PDF Copy); Brett Bingham (PDF Copy) Atlas No. B211698g Page I i Copyright©2021 Atlas Technical Consultants �TrT-G7T�1 CONTENTS 1. INTRODUCTION................................................................................................................. 1 1.1 Project Description ..................................................................................................... 1 1.2 Authorization .............................................................................................................. 1 1.3 Scope of Investigation................................................................................................ 1 2. SITE DESCRIPTION........................................................................................................... 2 2.1 Site Access ................................................................................................................ 2 2.2 General Site Characteristics....................................................................................... 2 2.3 Regional Site Climatology and Geochemistry............................................................. 2 3. SEISMIC SITE EVALUATION ............................................................................................ 2 3.1 Geoseismic Setting .................................................................................................... 2 3.2 Seismic Design Parameter Values ............................................................................. 3 4. SOILS EXPLORATION....................................................................................................... 3 4.1 Exploration and Sampling Procedures........................................................................ 3 4.2 Laboratory Testing Program....................................................................................... 4 4.3 Soil and Sediment Profile........................................................................................... 4 4.4 Volatile Organic Scan................................................................................................. 5 5. SITE HYDROLOGY............................................................................................................ 5 5.1 Groundwater.............................................................................................................. 5 5.2 Soil Infiltration Rates .................................................................................................. 6 6. FOUNDATION AND SLAB DISCUSSION AND RECOMMENDATIONS............................ 6 6.1 Foundation Design Recommendations....................................................................... 7 6.2 Floor Slab-on-Grade................................................................................................... 7 7. PAVEMENT DISCUSSION AND RECOMMENDATIONS................................................... 8 7.1 Flexible Pavement Section......................................................................................... 8 7.2 Pavement Subgrade Preparation ............................................................................... 9 7.3 Common Pavement Section Construction Issues....................................................... 9 8. CONSTRUCTION CONSIDERATIONS .............................................................................10 8.1 Earthwork..................................................................................................................10 8.2 Dry Weather..............................................................................................................11 8.3 Wet Weather.............................................................................................................11 8.4 Soft Subgrade Soils...................................................................................................11 8.5 Frozen Subgrade Soils..............................................................................................12 8.6 Structural Fill .............................................................................................................12 8.7 Backfill of Walls.........................................................................................................13 8.8 Excavations...............................................................................................................14 8.9 Groundwater Control.................................................................................................14 9. GENERAL COMMENTS....................................................................................................14 Atlas No. B211698g Page I ii Copyright©2021 Atlas Technical Consultants 10. REFERENCES.................................................................................................................15 TABLES Table 1 — Seismic Design Values................................................................................................3 Table 2 — Groundwater Data.......................................................................................................5 Table 3 — Soil Bearing Capacity..................................................................................................7 Table 4 — Gravel Equivalent Method Flexible Pavement Specifications ......................................9 Appendix I Warranty and Limiting Conditions Appendix 11 Vicinity Map Appendix III Site Map Appendix IV Geotechnical Investigation Test Pit Log Appendix V Geotechnical General Notes Appendix VI AASHTO Pavement Design Appendix VI Important Information About This Geotechnical Engineering Report Atlas No. B211698g Page I iii Copyright©2021 Atlas Technical Consultants 1. INTRODUCTION This report presents results of a geotechnical investigation and analysis in support of data utilized in design of structures as defined in the 2018 International Building Code (IBC). Information in support of groundwater and stormwater issues pertinent to the practice of Civil Engineering is included. Observations and recommendations relevant to the earthwork phase of the project are also presented. Revisions in plans or drawings for the proposed structure(s) from those enumerated in this report should be brought to the attention of the soils engineer to determine whether changes in the provided recommendations are required. Deviations from noted subsurface conditions, if encountered during construction, should also be brought to the attention of the soils engineer. 1.1 Project Description The proposed development is in the southern portion of the City of Meridian, Ada County, ID, and occupies a portion of the W'/2SW'/4 of Section 19, Township 3 North, Range 1 East, Boise Meridian. This project will consist of construction of an unknown number of townhouses. The site to be developed is approximately 1.2 acres. Total settlements are limited to 1 inch. Loads of up to 4,000 pounds per lineal foot for wall footings, and column loads of up to 50,000 pounds were assumed for settlement calculations. Additionally, assumptions have been made for traffic loading of pavements. Retaining walls are not anticipated as part of the project. Atlas has been informed that planned finished floor elevation will be approximately 12 inches above existing grade. 1.2 Authorization Authorization to perform this exploration and analysis was given in the form of a written authorization to proceed from Mr. Randy Haverfield of Architecture Northwest, P.A. to Jacob Schlador of Atlas Technical Consultants (Atlas), on June 9, 2021. Said authorization is subject to terms, conditions, and limitations described in the Professional Services Contract entered into between Architecture Northwest, P.A. and Atlas. Our scope of services for the proposed development has been provided in our proposal dated April 16, 2021 and repeated below. 1.3 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. Atlas No. B211698g Page11 Copyright©2021 Atlas Technical Consultants 2. SITE DESCRIPTION 2.1 Site Access Access to the site may be gained via State Highway 55 to the Meridian Road exit. Proceed south on Meridian Road approximately 0.72 mile to its intersection with Rosalyn Drive. From this intersection, proceed east on Rosalyn Drive 0.13 mile to the site, which is located on the north side of the road. The location is depicted on site maps included in the Appendix. 2.2 General Site Characteristics The site to be developed is approximately 1.2 acres in size. Currently, a residence is present in the southern portion of the site. The remainder of the site consists of undeveloped land. Residential developments are located north of the site, south of Rosalyn Drive, and east of Blackspur Way. Vegetation on the site consists primarily of landscape trees and grasses around the residence and in the northeast corner of the property. The site is relatively flat and level. 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 drainage from off-site sources. Stormwater drainage collection and retention systems are not in place on the project site, but currently exist as curb, gutter, and drop inlets along East Rosalyn Drive. 2.3 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 roughly -25°F to 111°F. Winds are generally from the northwest or southeast with an annual average wind speed of approximately 9 miles per hour (mph) and a maximum of 62 mph. Soils and sediments in the area are primarily derived from siliceous materials and exhibit low electro-chemical potential for corrosion of metals or concretes. Local aggregates are generally appropriate for Portland cement and lime cement mixtures. Surface water, groundwater, and soils in the region typically have pH levels ranging from 7.2 to 8.2. 3. SEISMIC SITE EVALUATION 3.1 Geoseismic Setting Soils on site are classed as Site Class D in accordance with Chapter 20 of the American Society of Civil Engineers (ASCE) publication ASCE/SEI 7-16. Structures constructed on this site should be designed per IBC requirements for such a seismic classification. Our investigation 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. Atlas No. B211698g Page12 Copyright©2021 Atlas Technical Consultants 3.2 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 0.196 is appropriate for the project site based on a Site Class D. 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, SMs, and at 1-second period, SMI, are adjusted for site class effects as required by the 2018 IBC. Design spectral response acceleration parameters as presented in the 2018 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). Table 1 — Seismic Design Values Site Class D "Stiff Soil' Ss 0.286 (g) SI 0.105 (g) Fa 1.571 F 2.391 Sens 0.450 SMI 0.250 Sos 0.300 Sol 0.167 4. 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 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. Atlas No. B211698g Page 13 Copyright©2021 Atlas Technical Consultants 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. Atlas recommends that these logs not be used to estimate fill material quantities. 4.2 Laboratory Testing Program Along with our field investigation, a supplemental laboratory testing program was conducted to determine additional pertinent engineering characteristics of subsurface materials 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 in the Appendix. The laboratory testing program for this report included: Atterberg Limits Testing — ASTM D4318, Grain Size Analysis — ASTM C117/C136. 4.3 Soil and Sediment Profile The profile below represents a generalized interpretation for the project site. Note that on site soils strata, encountered between test pit locations, may vary from the individual soil profiles presented in the logs, which can be found in the Appendix. Various fill materials were encountered at ground surface. These materials were brown, dry to slightly moist, and medium stiff to stiff, with fine to coarse-grained sand and fine to coarse gravel. Organic materials were measured to depths of roughly 1 foot bgs. Lean clays and sandy silts were encountered beneath surficial fill materials. These fine-grained soils were brown to light brown, dry to slightly moist, medium stiff to stiff, and contained fine to coarse-grained sand. Weak cementation was noted in test pit 2. Silty sand and clayey sand sediments were observed below the fine-grained soils. These sediments were brown, slightly moist to moist, and medium dense to dense, with fine to coarse-grained sand. Moderate cementation was noted in test pit 1 from 5.5 to 6.0 feet bgs. At depth, poorly graded gravel with sand sediments were exposed. Poorly graded gravels were light brown to brown, slightly moist to moist, and medium dense. Fine to coarse-grained sand, fine to coarse gravel, and 4-inch-minus cobbles were noted throughout. 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. Atlas No. B211698g Page14 Copyright©2021 Atlas Technical Consultants �TrT-G7T��. 4.4 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. No groundwater was encountered. SI1 E 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 not encountered in test pits advanced to a maximum depth of 16.0 feet bgs. Soil moistures in the test pits were generally dry to slightly moist within surficial soils. Within the poorly graded gravel with sand, clayey sand and silty sand, soil moistures graded from slightly moist to moist. 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. Atlas has previously performed 7 geotechnical investigations within 0.50 mile of the project site. Information from these investigations has been provided in the table below. Table 2 — Groundwater Data rApproximate Distance Groundwater Depth tio ff Date r from Site (mile) Direc n from Site it (feet . . June 2021 0.21 Northwest Not Encountered to 12.5 January 2005 0.31 South Not Encountered to 21.5 October 2019 0.41 South Not Encountered to 13.6 May 2004 0.45 Southwest Not Encountered to 15.8 July 2006 0.36 Northwest 13.1 to 14.2 July 2019 0.43 Northwest Not Encountered to 14.5 February 2013 0.45 Northwest Not Encountered to 15.9 Furthermore, according to United States Geological Survey (USGS) monitoring well data within approximately 0.09 mile of the project site, groundwater was measured at depths ranging between 20 and 33 feet bgs, which equates to groundwater elevations of 2,623 to 2,608 feet above mean sea level (msl). Atlas No. B211698g Page 15 Copyright©2021 Atlas Technical Consultants �/��M" ■ �TrT-G tv_ 1. Based on evidence of this investigation and background knowledge of the area, Atlas estimates groundwater depths to remain greater than approximately 13 feet bgs throughout the year. This depth can be confirmed through long-term groundwater monitoring. Since this is an estimated depth and seasonal groundwater levels fluctuate, actual levels should be confirmed by periodic groundwater data collected from the piezometer installed in test pit 1. If desired, Atlas is available to perform this monitoring. 5.2 Soil Infiltration Rates Soil permeability, which is a measure of the ability of a soil to transmit a fluid, was not tested in the field. Given the absence of direct measurements, for this report an estimation of infiltration is presented using generally recognized values for each soil type and gradation. Of soils comprising the generalized soil profile for this study, lean clay 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. Clayey sand sediments typically have infiltration rates ranging from 2 to 6 inches per hour. Silty sand sediments usually display rates of 4 to 8 inches per hour. Calcium carbonate cementation encountered in the clayey sand and sandy silt soils 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. It is recommended that infiltration facilities constructed on the site be extended into native poorly graded gravel with sand sediments. Excavation depths of approximately 10 to 11.3 feet bgs should be anticipated to expose these poorly graded gravel with sand sediments. Because of the high soil permeability, ASTM C33 filter sand, or equivalent, should be incorporated into design of infiltration facilities. An infiltration rate of 8 inches per hour should be used in design. Actual infiltration rates should be confirmed at the time of construction. 6. FOUNDATION AND SLAB DISCUSSION AND RECOMMENDATIONS Various foundation types have been considered for support of the proposed structure(s). 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 structure(s) 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, the number of structures is unknown 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. Atlas No. B211698g Page 16 Copyright©2021 Atlas Technical Consultants WIN M 6.1 Foundation Design Recommendations Based on data obtained from the site and test results from various laboratory tests performed, Atlas recommends the following guidelines for the net allowable soil bearing capacity: Table 3 — Soil Bearing Capacity Footings must bear on competent, undisturbed, 1,5001bs/ft2 native lean clay soils, sandy silt soils, or compacted Not Required for Native structural fill. Existing fill materials must be Soil A 1/3increase is allowable completely removed from below foundation for short-term loading, elements.' Excavation depths ranging from roughly 95% for Structural Fill which is defined by 1 to 3 feet bgs should be anticipated to expose seismic events or proper bearing soils.2 designed wind speeds. 'It will be required for Atlas personnel to verify the bearing soil suitability for each structure at the time of construction. 2Depending on the time of year construction takes place,the subgrade soils may be unstable because of high moisture contents. If unstable conditions are encountered,over-excavation and replacement with granular structural fill and/or use of geotextiles may be required. The following sliding frictional coefficient values should be used: 1) 0.35 for footings bearing on native lean clay or sandy silt soils and 2) 0.45 for footings bearing on granular structural fill. A passive lateral earth pressure of 336 pounds per square foot per foot (psf/ft) should be used for lean clay or sandy silt soils. For compacted sandy gravel fill, a passive lateral earth pressure of 496 psf/ft should be used. Footings should be proportioned to meet either the stated soil bearing capacity or the 2018 IBC minimum requirements. 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, Atlas recommends continuous footings be suitably reinforced to make them as rigid as possible. For frost protection, the bottom of external footings should be 24 inches below finished grade. Based on the soil types encountered onsite, foundation drains are not needed. 9oor Slab-on-Grade Uncontrolled fill was encountered in portions of the site. Atlas 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 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 provided that all organic material is completely removed. Once final grades have been determined, Atlas is available to provide additional recommendations. Atlas No. B211698g Page 17 Copyright©2021 Atlas Technical Consultants �/��M" ■ p �TrT-G7T_Zr__. 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 should be provided below slabs-on-grade to provide drainage and a uniform and stable bearing surface. This should be a minimum of 4 inches in thickness and 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 302.1 R and ASTM E1745 publications. Upon request, Atlas can provide further consultation regarding installation. PAVEMENT DISCUSSION AND RECOMMENDATIONS As required by Ada County Highway District (ACHD), Atlas has used a traffic index of 6 to determine the necessary pavement cross-section for the site. Atlas 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. Based on experience with soils in the region, a subgrade Resistance Value (R-value) of 4 has been assumed for near-surface lean clay and sandy silt soils on site. 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. 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. A calculation sheet provided in the Appendix indicates the soils constant, traffic loading, traffic projections, and material constants used to calculate the pavement section. Atlas recommends that materials used in the construction of asphaltic concrete pavements meet the requirements of the ISPWC Standard Specification for Highway Construction. Construction of the pavement section should be in accordance with these specifications and should adhere to guidelines recommended in the section on Construction Considerations. Atlas No. B211698g Page 18 Copyright©2021 Atlas Technical Consultants �TrT-G7Tdr-W� Table 4— Gravel Equivalent Method Flexible Pavement Specifications Pavement Section Component Asphaltic Concrete 2.5 Inches Crushed Aggregate Base 4.0 Inches Structural Subbase 14.0 Inches Not Required for Native Soils Compacted Subgrade 12.0 Inches to 95% of ASTM D698 for Existing Fill Materials 'It will be required for Atlas personnel to verify subgrade competency at the time of construction. • Asphaltic Concrete: Asphalt mix design shall meet the requirements of ISPWC, Section 810 Class III plant mix. Materials shall be placed in accordance with ISPWC Standard Specifications for Highway Construction. • Aggregate Base: Material complying with ISPWC Standards for Crushed Aggregate Materials. • Structural Subbase: Granular structural fill material complying with the requirements detailed in the Structural Fill section of this report except that the maximum material diameter is no more than 2/3 the component thickness. Gradation and suitability requirements shall be per ISPWC Section 801, Table 1. 7.2 Pavement Subgrade Preparation Uncontrolled fill was encountered in portions of the site. Atlas 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 subgrade must be compacted to at least 95 percent of the maximum dry density as determined by ASTM D698. The excavated fill materials can be replaced in accordance with the Structural Fill section provided that all organic material and/or debris is completely removed. However, the existing fill materials are not suitable for use as either the base or subbase components of the recommended pavement section. Once final grades have been determined, Atlas is available to provide additional recommendations. 7.3 Common Pavement Section Construction Issues The subgrade upon which above pavement sections are to be constructed must be properly stripped, compacted (if indicated), inspected, and proof-rolled. Proof rolling of subgrade soils should be accomplished using a heavy rubber-tired, fully loaded, tandem-axle dump truck or equivalent. Verification of subgrade competence by Atlas personnel at the time of construction is required. Fill materials on the site must demonstrate the indicated compaction prior to placing material in support of the pavement section. Atlas anticipated that pavement areas will be subjected to moderate traffic. Atlas does not anticipate pumping material to become evident during compaction, but subgrade lean clays and sandy silts near and above optimum moisture contents may tend to pump. Pumping or soft areas must be removed and replaced with structural fill. Atlas No. B211698g Page 19 Copyright©2021 Atlas Technical Consultants �/��M" ■ �TrT-G tv— 1. 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. Atlas recommends that rigid concrete pavement be provided for heavy garbage receptacles. This will eliminate damage caused by the considerable loading transferred through the small steel wheels onto asphaltic concrete. Rigid concrete pavement should consist of Portland Cement Concrete Pavement (PCCP) generally adhering to ITD specifications for Urban Concrete. PCCP should be 6 inches thick on a 4-inch drainage fill course (see Floor Slab-on-Grade section), and should be reinforced with welded wire fabric. Control joints must be on 12-foot centers or less. 8. CONSTRUCTION CONSIDERATIONS Recommendations in this report are based upon structural elements of the project being founded on competent, native lean clay soils, sandy silt soils, or compacted structural fill. Structural areas should be stripped to an elevation that exposes these soil types. 8.1 Earthwork Excessively organic soils, deleterious materials, or disturbed soils generally undergo high volume changes when subjected to loads, which is detrimental to subgrade behavior in the area of pavements, floor slabs, structural fills, and foundations. Mature trees, brush and landscaped grasses with associated root systems were noted at the time of our investigation. It is recommended that organic or disturbed soils, if encountered, be removed to depths of 1 foot (minimum), and wasted or stockpiled for later use. However, in areas where trees are/were present, deeper excavation depths should be anticipated. Stripping depths should be adjusted in the field to assure that the entire root zone or disturbed zone or topsoil are removed prior to placement and compaction of structural fill materials. Exact removal depths should be determined during grading operations by Atlas personnel, and should be based upon subgrade soil type, composition, and firmness or soil stability. If underground storage tanks, underground utilities, wells, or septic systems are discovered during construction activities, they must be decommissioned then removed or abandoned in accordance with governing Federal, State, and local agencies. Excavations developed as the result of such removal must be backfilled with structural fill materials as defined in the Structural Fill section. Atlas No. B211698g Page110 Copyright©2021 Atlas Technical Consultants �/��M" ■ �TrT-G tv_ 1. Atlas should oversee subgrade conditions (i.e., moisture content) as well as placement and compaction of new fill (if required) after native soils are excavated to design grade. Recommendations for structural fill presented in this report can be used to minimize volume changes and differential settlements that are detrimental to the behavior of footings, pavements, and floor slabs. Sufficient density tests should be performed to properly monitor compaction. 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. 8.2 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. 8.3 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. 8.4 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 to perform any other necessary excavations. 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. Atlas No. B211698g Page 111 Copyright©2021 Atlas Technical Consultants • Construction roadways on soft subgrade soils should consist of a minimum 2-foot thickness of large cobbles of 4 to 6 inches in diameter with sufficient sand and fines to fill voids. Construction entrances should consist of a 6-inch thickness of clean, 2-inch minimum, angular drain-rock and must be a minimum of 10 feet wide and 30 to 50 feet long. During the construction process, top dressing of the entrance may be required for maintenance. • Scarification and aeration of subgrade soils can be employed to reduce the moisture content of wet subgrade soils. After stripping is complete, the exposed subgrade should be ripped or disked to a depth of 1'/z feet and allowed to air dry for 2 to 4 weeks. Further disking should be performed on a weekly basis to aid the aeration process. • Alternative soil stabilization methods include use of geotextiles, lime, and cement stabilization. Atlas is available to provide recommendations and guidelines at your request. 8.5 Frozen Subgrade Soils Prior to placement of structural fill materials or foundation elements, frozen subgrade soils must either be allowed to thaw or be stripped to depths that expose non-frozen soils and wasted or stockpiled for later use. Stockpiled materials must be allowed to thaw and return to near-optimal conditions prior to use as structural fill. The onsite, shallow lean clay and sandy silt soils are susceptible to frost heave during freezing temperatures. For exterior flatwork and other structural elements, adequate drainage away from subgrades is critical. Compaction and use of structural fill will also help to mitigate the potential for frost heave. Complete removal of frost susceptible soils for the full frost depth, followed by replacement with a non-frost susceptible structural fill, can also be used to mitigate the potential for frost heave. Atlas is available to provide further guidance/assistance upon request. 8.6 Structural Fill Soils recommended for use as structural fill are those classified as GW, GP, SW, and SIP 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 MIL) 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. Atlas No. B211698g Page112 Copyright©2021 Atlas Technical Consultants 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 %-inch) material and no more than 12 percent fines (passing No. 200 sieve). These fill materials should be placed in layers not to exceed 12 inches in loose thickness. Prior to placement of structural fill materials, surfaces must be prepared as outlined in the Construction Considerations section. Structural fill material should be moisture-conditioned to achieve optimum moisture content prior to compaction. For structural fill below footings, areas of compacted backfill must extend outside the perimeter of the footings for a distance equal to the thickness of fill between the bottom of foundation and underlying soils, or 5 feet, whichever is less. All fill materials must be monitored during placement and tested to confirm compaction requirements, outlined below, have been achieved. Each layer of structural fill must be compacted, as outlined below: • Below Structures and Rigid Pavements: A minimum of 95 percent of the maximum dry density as determined by ASTM D1557. • Below Flexible Pavements: A minimum of 92 percent of the maximum dry density as determined by ASTM D1557 or 95 percent of the maximum dry density as determined by ASTM D698. 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. 8.7 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. Atlas No. B211698g Page113 Copyright©2021 Atlas Technical Consultants 8.8 Excavations Shallow excavations that do not exceed 4 feet in depth may be constructed with side slopes approaching vertical. Below this depth, it is recommended that slopes be constructed in accordance with Occupational Safety and Health Administration (OSHA) regulations, Section 1926, Subpart P. Based on these regulations, on-site soils are classified as type "C" soil, and as such, excavations within these soils should be constructed at a maximum slope of 1'/2 feet horizontal to 1 foot vertical (11/2:1) for excavations up to 20 feet in height. Excavations in excess of 20 feet will require additional analysis. Note that these slope angles are considered stable for short-term conditions only, and will not be stable for long-term conditions. 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. 8.9 Groundwater Control Groundwater was not encountered during the investigation and is anticipated to be below the depth of most construction. Excavations below the water table will require a dewatering program. It may be possible to discharge dewatering effluent to remote portions of the site, to a sump, or to a pit. This will essentially recycle effluent, thus eliminating the need to enter into agreements with local drainage authorities. Should the scope of the proposed project change, Atlas should be contacted to provide more detailed groundwater control measures. Special precautions may be required for control of surface runoff and subsurface seepage. It is recommended that runoff be directed away from open excavations. Silty and clayey soils may become soft and pump if subjected to excessive traffic during time of surface runoff. Ponded water in construction areas should be drained through methods such as trenching, sloping, crowning grades, nightly smooth drum rolling, or installing a French drain system. Additionally, temporary or permanent driveway sections should be constructed if extended wet weather is forecasted. 9. GENERAL COMMENTS Based on the subsurface conditions encountered during this investigation and available information regarding the proposed structures, 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 structures, consultation with Atlas must be arranged as supplementary recommendations may be required. Suitability of subgrade soils and compaction of structural fill materials must be verified by Atlas personnel prior to placement of structural elements. Additionally, monitoring and testing should be performed to verify that suitable materials are used for structural fill and that proper placement and compaction techniques are utilized. Atlas No. B211698g Page114 Copyright©2021 Atlas Technical Consultants 10. REFERENCES American Association of State Highway and Transportation Officials (AASHTO)(1993). AASHTO Guide for Design of Pavement Structures 1993. Washington D.C.: AASHTO. American Concrete Institute (ACI) (2015). Guide for Concrete Floor and Slab Construction: ACI 302.1 R. Farmington Hills, MI: ACI. American Society of Civil Engineers (2021). ASCE 7 Hazards Tool: Web Interface [Online] Available: <https://asce7hazardtool.online/> (2021). American Society of Civil Engineers (ASCE) (2013). Minimum Design Loads for Buildings and Other Structures: ASCE/SEI 7-16. Reston, VA: ASCE. American Society for Testing and Materials (ASTM) (2017). Standard Test Method for Materials Finer than 75-um (No. 200) Sieve in Mineral Aggregates by Washing: ASTM C117. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (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) (2014). Standard Test Methods for California Bearing Ratio: ASTM D1883. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (2017). Standard Practice for Classification of Soils for Engineering Purposes(Unified Soil Classification System):ASTM D2487.West Conshohocken, PA:ASTM. American Society for Testing and Materials (ASTM) (2017). Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils: ASTM D4318. West Conshohocken, PA: ASTM. American Society for Testing and Materials (ASTM) (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/> (2021). International Building Code Council (2018). International Building Code, 2018. Country Club Hills, IL: Author. Local Highway Technical Assistance Council (LHTAC) (2017). Idaho Standards for Public Works Construction, 2017. Boise, ID: Author. 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> (2021). Atlas No. B211698g Page115 Copyright©2021 Atlas Technical Consultants rrN+M= 'T�� -I U.S. Geological Survey (2021). National Water Information System: Web Interface. [Online] Available: <http://waterdata.usgs.gov/nwis> (2021). Atlas No. B211698g Page116 Copyright©2021 Atlas Technical Consultants Appendix I WARRANTY AND LIMITING CONDITIONS Atlas warrants that findings and conclusions contained herein have been formulated in accordance with generally accepted professional engineering practice in the fields of foundation engineering, soil mechanics, and engineering geology only for the site and project described in this report. These engineering methods have been developed to provide the client with information regarding apparent or potential engineering conditions relating to the site within the scope cited above and are necessarily limited to conditions observed at the time of the site visit and research. Field observations and research reported herein are considered sufficient in detail and scope to form a reasonable basis for the purposes cited above. Exclusive Use This report was prepared for exclusive use of the property owner(s), at the time of the report, and their retained design consultants ("Client"). Conclusions and recommendations presented in this report are based on the agreed-upon scope of work outlined in this report together with the Contract for Professional Services between the Client and Atlas Technical Consultants ("Consultant"). Use or misuse of this report, or reliance upon findings hereof, by parties other than the Client is at their own risk. Neither Client nor Consultant make representation of warranty to such other parties as to accuracy or completeness of this report or suitability of its use by such other parties for purposes whatsoever, known or unknown, to Client or Consultant. Neither Client nor Consultant shall have liability to indemnify or hold harmless third parties for losses incurred by actual or purported use or misuse of this report. No other warranties are implied or expressed. Report Recommendations are Limited and Subject to Misinterpretation There is a distinct possibility that conditions may exist that could not be identified within the scope of the investigation or that were not apparent during our site investigation. Findings of this report are limited to data collected from noted explorations advanced and do not account for unidentified fill zones, unsuitable soil types or conditions, and variability in soil moisture and groundwater conditions. To avoid possible misinterpretations of findings, conclusions, and implications of this report, Atlas should be retained to explain the report contents to other design professionals as well as construction professionals. Since actual subsurface conditions on the site can only be verified by earthwork, note that construction recommendations are based on general assumptions from selective observations and selective field exploratory sampling. Upon commencement of construction, such conditions may be identified that require corrective actions, and these required corrective actions may impact the project budget. Therefore, construction recommendations in this report should be considered preliminary, and Atlas should be retained to observe actual subsurface conditions during earthwork construction activities to provide additional construction recommendations as needed. Atlas No. B211698g Page117 Copyright©2021 Atlas Technical Consultants Since geotechnical reports are subject to misinterpretation, do not separate the soil logs from the report. Rather, provide a copy of, or authorize for their use, the complete report to other design professionals or contractors. Locations of exploratory sites referenced within this report should be considered approximate locations only. For more accurate locations, services of a professional land surveyor are recommended. This report is also limited to information available at the time it was prepared. In the event additional information is provided to Atlas following publication of our report, it will be forwarded to the client for evaluation in the form received. Environmental Concerns Comments in this report concerning either onsite conditions or observations, including soil appearances and odors, are provided as general information. These comments are not intended to describe, quantify, or evaluate environmental concerns or situations. Since personnel, skills, procedures, standards, and equipment differ, a geotechnical investigation report is not intended to substitute for a geoenvironmental investigation or a Phase II/III Environmental Site Assessment. If environmental services are needed, Atlas can provide, via a separate contract, those personnel who are trained to investigate and delineate soil and water contamination. Atlas No. B211698g Page118 Copyright©2021 Atlas Technical Consultants Vicinity Map Figure 1 z = EKING 5T a MAP NOTES: ❑ IrrI n N -Delorme Street Atlas W.FRANKLIN.RD to �- -_N_ -- � �FRgNKLIN.RD ;�—— _ E.FRANKLIN RD a—�—�_�,�. _ �^ — N Not to Scale ., g D a a o �� E Si �. ❑ d �Cr T C -❑ � Z C n N -P y� rn yr m m ❑ G7 LEGEND �y o y z t' W i — �'I o Approximate Site rn c N PENNWOQD 57(n w! E WATERTOWER LN 70 oo M Location L�. } En to �' ,,;y cn N � Q � !I � ¢ w n E CORPORATE DR c y c Ui m r A. tom z D ON < _ —WALTMAN LN yy A, A c n n U1 N m �' P rn u7 A- CENTRAL DR p rn rr C It 1! P" p CON z W VERBENA DR m D z ��� D r n Q► - ;l m 30 55 30 55 M Site Location N o m w n 3 C a _ E OVERLAND-RD p0 (AE SHEPHERD 5T z ^F�� O z 's' F �G Q E 56RIoI ST__ m a (n �f2 oR 3 E PEACOCK ST o 10 3._ 'L=•�..c v� E PUFFIN;ST rp F ��: = Rfrl .f` E MASTIFF ST R � mo� F 0 2 V1 rn r�r NIP Al'Q � Bin ham Multi-FamilyHousing r �'p ��E S O'P �9 a n 200 East Rosalyn Drive S f7I! O O Alrypt CL► inrn Meridian,ID zf �CO ��[� CIA DR D9` ❑n. �� C rn w g Modified from Delorme by:CCW Ott �. } a' M June 30,2021 ❑ o Uj S 5 ° b P Drawing:B211698g G � ❑ w � � � ¢ccG ui a NERS Ln wa z gpc 3 m n Q �91- x N ❑ o yr in 69 0 z =¢ n._? /1h n z u� z�� Q'y ❑ n 0 Y Q co j ❑ 2791 S.Victory View Way Phone: (208)376-4748 y �CF ❑ ;Q Q Q �� C Boise,ID 83709 Fax: (208)322-6515 X 0 f 1 N m q ➢ Web: oneatlas.com Site Map Figure 2 i NOTES: N •Not to Scale ------------------- - --BLUE LARK COURT------------- - - - - - i LEGEND ' Approximate Site Boundary i Approximate Atlas Test i Pit Location 8 i i i Approximate Atlas Test Pit Location i with Piezometer Existing Structures TP-1 � ® i i TP-2 8 � Cn i i � W r n �7 \� Bin ham Multi-Family Housing �� __----_----------� 200 Ea Rosalyn Drive Meridiann,,IDID i i Drawn by:CCW \ ' June 30,2021 ` - ---------------------ROSALYNDRIVE-------------------- i Drawing:B211698g i i i i 2791 S.Victory View Way Phone: (208)376-4748 Boise,ID 83709 Fax: (208)322-6515 Web: oneatlas.com �TrT-G7T�1 Appendix IV GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-1 Latitude: 43.583064 Date Advanced: June 22, 2021 Longitude: -116.391280 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Bryar Jensen Total Depth: 16.0 feet bgs Depth Field Description and USCS Soil and Sample Sample Depth Qp Lab • •s) Sediment Classification • bgs) Test I Lean Clay Fill (CL-FILL): Brown, dry to slightly 0.0-1.0 moist, medium stiff to stiff, with fine to coarse- grained sand and fine to coarse gravel. 1.0-5.5 Lean Clay (CL): Brown, dry to slightly moist, GS 1.0-1.5 A medium stiff to stiff, with fine grained sand. Clayey Sand (SC): Brown, slightly moist to moist, medium dense to dense, with fine to 5.5-10.0 coarse-grained sand. --Moderate cementation encountered from 5.5 to 6.0 bgs. Poorly Graded Gravel with Sand (GP): Light 10.0-16.0 brown, slightly moist to moist, medium dense, with fine to coarse-grained sand,fine to coarse gravel, and 4-inch-minus cobbles. Notes:See Site Map for test pit location. Piezometer installed to a depth of 16.0 feet bgs. A 20.3 30 13 100 100 99 95 87.9 Atlas No. B211698g Page 121 Copyright©2021 Atlas Technical Consultants �TrT-G7T�-1 GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-2 Latitude: 43.582960 Date Advanced: June 22, 2021 Longitude: -116.390846 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Bryar Jensen Total Depth: 12.3 feet bgs DepthDepth Field Description and USCS Soil and Sample Sample . . . . . . • St 11 Silty Clay with Sand and Gravel Fill (CL-ML- FILL): Brown,dry, medium stiff to stiff,with fine 0.0-3.0 to coarse-grained sand and fine to coarse 0.75-1.5 gravel. --Organic material encountered to 1.0 foot bgs. Sandy Silt (ML): Light brown, dry to slightly moist, medium stiff to stiff, with fine to coarse- 3.0-6.1 grained sand. --Weak cementation encountered from 3.0 to 4.0 feet bgs. Silty Sand (SM): Brown,slightly moist to moist, 6.1-11.3 medium dense, with fine to coarse-grained sand. Poorly Graded Gravel with Sand (GP): Brown, 11.3-12.3 slightly moist to moist, medium dense, with fine to coarse-grained sand and fine to coarse gravel. Notes:See Site Map for test pit location. Atlas No. B211698g Page 122 Copyright©2021 Atlas Technical Consultants �TrT-G7Tdr-W1 Appendix V GEOTECHNICAL GENERAL NOTES Unified Soil Classification System Major Divisions Symbol Soil Descriptions Gravel & GW Well-graded ravels; ravel/sand mixtures with little or no fines Coarse- Gravelly Soils GP Poorly-graded ravels; ravel/sand mixtures with little or no fines Grained < 50% GM Silty gravels; poorly-graded ravel/sand/silt mixtures Soils < coarse GC Clayey gravels; poorly-graded gravel/sand/clay mixtures 50% Sand & Sandy SW Well-graded sands; gravelly sands with little or no fines passes Soils > 50% SP Poorl - raded sands; gravelly sands with little or no fines No.200 coarse SM Silty sands; poorly-graded sand/gravel/silt mixtures sieve fraction Sc Clayey sands; poorly-graded sand/gravel/clay mixtures Fine- ML Inorganic silts; sandy, gravellyor clayey silts Grained Silts & Clays CL Lean clays; inorganic, gravelly, sandy, or silty, low to medium- Soils > LL < 50 lasticit cla s 50% OL Organic, low-plasticity clays and silts passes MH Inorganic, elastic silts; sand ravel) or clayey elastic silts No.200 Silts &Clays CH Fat clays high-plasticity, inorganic clays sieve LL > 50 OH Organic, medium to high-plasticity clays and silts Highly Organic Soils PT Peat, humus, h dric soils with high organic content Relative Density and Consistency ture Content and Cementation Coarse-Grained Soils SPT Blow Counts (N) Description Field Test Very Loose: <4 Dry Absence of moisture, dry to touch Loose: 4-10 Slightly Moist Damp, but no visible moisture Medium Dense: 10-30 Moist Visible moisture Dense: 30-50 Wet Visible free water Very Dense: >50 Saturated Soil is usually below water table Fine-Grained Soils SPT Blow Counts N Description Field Test Very Soft: <2 Weak Crumbles or breaks with handling or Soft: 2-4 slight finger pressure Medium Stiff: 4-8 Moderate Crumbles or breaks with Stiff: 8-15 considerable finger pressure Very Stiff: 15-30 Strong Will not crumble or break with finger Hard: >30 pressure Particle Size ]�� Acronym List Boulders: > 12 in. GS grab sample Cobbles: 12 to 3 in. LL Liquid Limit Gravel: 3 in. to 5 mm M moisture content Coarse-Grained Sand: 5 to 0.6 mm NP non-plastic Medium-Grained Sand: 0.6 to 0.2 mm PI Plasticity Index Fine-Grained Sand: 0.2 to 0.075 mm Qp penetrometer value, unconfined compressive Silts: 0.075 to 0.005 mm strength, tsf Clays: < 0.005 mm V vane value, ultimate shearing strength, tsf Atlas No. B211698g Page 123 Copyright©2021 Atlas Technical Consultants Appendix VI GRAVEL EQUIVALENT METHOD PAVEMENT DESIGN Pavement Section Design Location: Bingham Multi Family, Residential Roadways Average Daily Traffic Count: 170 All Lanes&Both Directions Design Life: 20 Years Traffic Index: 6.00 Climate Factor: 1 R-Value of Subgrade: 4.00 Subgrade CBR Value: 2 Subgrade Mr: 3,000 R-Value of Aggregate Base: 80 R-Value of Granular Borrow: 60 Subgrade R-Value: 4 Expansion Pressure of Subgrade: 1.40 Unit Weight of Base Materials: 130 Total Design Life 18 kip ESAL's: 33,131 ASPHALTIC CONCRETE: Gravel Equivalent,Calculated: 0.384 Thickness: 0.196923077 Use= 2.5 Inches Gravel Equivalent,ACTUAL: 0.41 CRUSHED AGGREGATE BASE: Gravel Equivalent(Ballast): 0.768 Thickness: 0.329 Use= 4 Inches Gravel Equivalent,ACTUAL: 0.773 SUBBASE: Gravel Equivalent(Ballast): 1.843 Thickness: 1.070 Use= 14 Inches Gravel Equivalent,ACTUAL: 1.940 TOTAL Thickness: 1.708 Thickness Required by Exp. Pressure: 1.551 Design ACHD Depth Substitution Inches Ratios Asphaltic Concrete(at least 2.5): 2.50 1.95 Asphalt Treated Base(at least 4.2): 0.00 Cement Treated Base(at least 4.2): 0.00 Crushed Aggregate Base(at least 4.2): 4.00 1.10 Subbase(at least 4.2): 14.00 1.00 Atlas No. B211698g Page 124 Copyright©2021 Atlas Technical Consultants IMPOPIOnt InfOPM81100 Rhout ■ GeolechnicalmEngineeping Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help. The Geoprofessional Business Association (GBA) will not likely meet the needs of a civil-works constructor or even a has prepared this advisory to help you—assumedly different civil engineer.Because each geotechnical-engineering study a client representative—interpret and apply this is unique,each geotechnical-engineering report is unique,prepared geotechnical-engineering report as effectively as solely for the client. possible. In that way, you can benefit from a lowered Likewise,geotechnical-engineering services are performed for a specific exposure to problems associated with subsurface project and purpose.For example,it is unlikely that a geotechnical- conditions at project sites and development of engineering study for a refrigerated warehouse will be the same as them that,for decades, have been a principal cause one prepared for a parking garage;and a few borings drilled during of construction delays, cost overruns, claims, a preliminary study to evaluate site feasibility will not be adequate to and disputes. If you have questions or want more develop geotechnical design recommendations for the project. information about any of the issues discussed herein, contact your GBA-member geotechnical engineer. Do not rely on this report if your geotechnical engineer prepared it: Active engagement in GBA exposes geotechnical • for a different client; engineers to a wide array of risk-confrontation • for a different project or purpose; techniques that can be of genuine benefit for • for a different site(that may or may not include all or a portion of everyone involved with a construction project. the original site);or before important events occurred at the site or adjacent to it; e.g.,man-made events like construction or environmental Understand the Geotechnical-Engineering Services remediation,or natural events like floods,droughts,earthquakes, Provided for this Report or groundwater fluctuations. Geotechnical-engineering services typically include the planning, collection,interpretation,and analysis of exploratory data from Note,too,the reliability of a geotechnical-engineering report can widely spaced borings and/or test pits.Field data are combined be affected by the passage of time,because of factors like changed with results from laboratory tests of soil and rock samples obtained subsurface conditions;new or modified codes,standards,or from field exploration(if applicable),observations made during site regulations;or new techniques or tools.If you are the least bit uncertain reconnaissance,and historical information to form one or more models about the continued reliability of this report,contact your geotechnical of the expected subsurface conditions beneath the site.Local geology engineer before applying the recommendations in it.A minor amount and alterations of the site surface and subsurface by previous and of additional testing or analysis after the passage of time-if any is proposed construction are also important considerations.Geotechnical required at all-could prevent major problems. engineers apply their engineering training,experience,and judgment to adapt the requirements of the prospective project to the subsurface Read this Report in Full model(s). Estimates are made of the subsurface conditions that Costly problems have occurred because those relying on a geotechnical- will likely be exposed during construction as well as the expected engineering report did not read the report in its entirety.Do not rely on performance of foundations and other structures being planned and/or an executive summary.Do not read selective elements only.Read and affected by construction activities. refer to the report in full. The culmination of these geotechnical-engineering services is typically a You Need to Inform Your Geotechnical Engineer geotechnical-engineering report providing the data obtained,a discussion About Change of the subsurface model(s),the engineering and geologic engineering Your geotechnical engineer considered unique,project-specific factors assessments and analyses made,and the recommendations developed when developing the scope of study behind this report and developing to satisfy the given requirements of the project.These reports may be the confirmation-dependent recommendations the report conveys. titled investigations,explorations,studies,assessments,or evaluations. Typical changes that could erode the reliability of this report include Regardless of the title used,the geotechnical-engineering report is an those that affect: engineering interpretation of the subsurface conditions within the context - the site's size or shape; of the project and does not represent a close examination,systematic inquiry,or thorough investigation of all site and subsurface conditions. the elevation,configuration,location,orientation, function or weight of the proposed structure and Geotechnical-Engineering Services are Performed the desired performance criteria; the composition of the design team;or for Specific Purposes, Persons, and Projects, . project ownership. and At Specific Times Geotechnical engineers structure their services to meet the specific As a general rule,always inform your geotechnical engineer of project needs,goals,and risk management preferences of their clients.A or site changes-even minor ones-and request an assessment of their geotechnical-engineering study conducted for a given civil engineer impact.The geotechnical engineer who prepared this report cannot accept responsibility or liability for problems that arise because the geotechnical conspicuously that you've included the material for information purposes engineer was not informed about developments the engineer otherwise only.To avoid misunderstanding,you may also want to note that would have considered. "informational purposes"means constructors have no right to rely on the interpretations,opinions,conclusions,or recommendations in the Most Of the "Findings" Related in This Report report.Be certain that constructors know they may learn about specific Are Professional Opinions project requirements,including options selected from the report,only Before construction begins,geotechnical engineers explore a site's from the design drawings and specifications.Remind constructors subsurface using various sampling and testing procedures.Geotechnical that they may perform their own studies if they want to,and be sure to engineers can observe actual subsurface conditions only at those specific allow enough time to permit them to do so.Only then might you be in locations where sampling and testing is performed.The data derived from a position to give constructors the information available to you,while that sampling and testing were reviewed by your geotechnical engineer, requiring them to at least share some of the financial responsibilities who then applied professional judgement to form opinions about stemming from unanticipated conditions.Conducting prebid and subsurface conditions throughout the site.Actual sitewide-subsurface preconstruction conferences can also be valuable in this respect. conditions may differ-maybe significantly-from those indicated in this report.Confront that risk by retaining your geotechnical engineer Read Responsibility Provisions Closely to serve on the design team through project completion to obtain Some client representatives,design professionals,and constructors do informed guidance quickly,whenever needed. not realize that geotechnical engineering is far less exact than other engineering disciplines.This happens in part because soil and rock on This Report's Recommendations Are project sites are typically heterogeneous and not manufactured materials Confirmation-Dependent with well-defined engineering properties like steel and concrete.That The recommendations included in this report-including any options or lack of understanding has nurtured unrealistic expectations that have alternatives-are confirmation-dependent.In other words,they are not resulted in disappointments,delays,cost overruns,claims,and disputes. final,because the geotechnical engineer who developed them relied heavily TO confront that risk,geotechnical engineers commonly include on judgement and opinion to do so.Your geotechnical engineer can finalize explanatory provisions in their reports.Sometimes labeled"limitations,' the recommendations only after observing actual subsurface conditions many of these provisions indicate where geotechnical engineers' exposed during construction.If through observation your geotechnical responsibilities begin and end,to help others recognize their own engineer confirms that the conditions assumed to exist actually do exist, responsibilities and risks.Read these provisions closely.Ask questions. the recommendations can be relied upon,assuming no other changes have Your geotechnical engineer should respond fully and frankly. occurred.The geotechnical engineer who prepared this report cannot assume responsibility or liabilityfor confirmation-dependent recommendations fyou Geoenvironmental Concerns Are Not Covered fail to retain that engineer to perform construction observation. The personnel,equipment,and techniques used to perform an environmental study-e.g.,a"phase-one"or"phase-two"enviromnental This Report Could Be Misinterpreted site assessment-differ significantly from those used to perform a Other design professionals'misinterpretation of geotechnical- geotechnical-engineering study.For that reason,a geotechnical-engineering engineering reports has resulted in costly problems.Confront that risk report does not usually provide environmental findings,conclusions,or by having your geotechnical engineer serve as a continuing member of recommendations;e.g.,about the likelihood of encountering underground the design team,to: storage tanks or regulated contaminants.Unanticipated subsurface • confer with other design-team members; environmental problems have led to project failures.If you have not • help develop specifications; obtained your own environmental information about the project site, review pertinent elements of other design professionals'plans and ask your geotechnical consultant for a recommendation on how to find specifications;and environmental risk-management guidance. • be available whenever geotechnical-engineering guidance is needed. Obtain Professional Assistance to Deal with You should also confront the risk of constructors misinterpreting this Moisture Infiltration and Mold report.Do so by retaining your geotechnical engineer to participate in While your geotechnical engineer may have addressed groundwater, prebid and preconstruction conferences and to perform construction- water infiltration,or similar issues in this report,the engineer's phase observations. services were not designed,conducted,or intended to prevent migration of moisture-including water vapor-from the soil Give Constructors a Complete Report and Guidance through building slabs and walls and into the building interior,where Some owners and design professionals mistakenly believe they can shift it can cause mold growth and material-performance deficiencies. unanticipated-subsurface-conditions liability to constructors by limiting Accordingly,proper implementation of the geotechnical engineer's the information they provide for bid preparation.To help prevent recommendations will not of itself be sufficient to prevent the costly,contentious problems this practice has caused,include the moisture infiltration.Confront the risk of moisture infiltration by complete geotechnical-engineering report,along with any attachments including building-envelope or mold specialists on the design team. or appendices,with your contract documents,but be certain to note Geotechnical engineers are not building-envelope or mold specialists. 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