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HomeMy WebLinkAboutEx 17_Geotech Report.pdfassociated earth sciences incorporated Associated Earth Sciences, Inc. 911 5th Avenue Kirkland, WA 98033 P (425) 827 7701 Updated Subsurface Exploration and Geotechnical Engineering Report RENTON SCHOOL DISTRICT ELEMENTARY SCHOOL NO. 16 Renton, Washington Prepared For: RENTON SCHOOL DISTRICT December 22, 2020 Project No. 20180398E002 Kirkland | Tacoma | Mount Vernon 425-827-7701 | www.aesgeo.com December 22, 2020 Project No. 20180398E002 Renton School District 7812 South 124th Street Seattle, Washington 98178 Attention: Ms. Traci Brewer-Rogstad Subject: Updated Subsurface Exploration and Geotechnical Engineering Report Renton School District Elementary School No. 16 Renton, Washington Dear Ms. Brewer-Rogstad: We are pleased to present this updated geotechnical engineering report for the referenced project. This report summarizes the results of our subsurface exploration and presents recommendations for design and construction of a new school at the site. An earlier version of this report was prepared, dated November 23, 2019. This update incorporates changes to Section 6.4, reflecting the new 2018 IBC codes. We have enjoyed working with you on this study and are confident that the recommendations presented in this report will aid in the successful completion of your project. If you should have any questions or if we can be of additional help to you, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ______________________________ Kurt D. Merriman, P.E. Senior Principal Engineer KDM/ld 20180398E002-4 UPDATED SUBSURFACE EXPLORATION AND GEOTECHNICAL ENGINEERING REPORT RENTON SCHOOL DISTRICT ELEMENTARY SCHOOL NO. 16 Renton, Washington Prepared for: Renton School District 7812 South 124th Street Seattle, Washington 98178 Prepared by: Associated Earth Sciences, Inc. 911 5th Avenue Kirkland, Washington 98033 425-827-7701 December 22, 2020 Project No. 20180398E002 Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Project and Site Conditions December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 1 I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report summarizes the results of our subsurface exploration and geotechnical engineering study for the Renton Elementary School No. 16 project. Recommendations in this report are based on a “Site Coordination Plan” by Hutteball + Oremus Architecture dated October 21, 2020 and an ALTA survey titled “Renton School District Chelan Ave. NE Project” by Terrane dated October 12, 2020. The site location is shown on the “Vicinity Map,” Figure 1. The approximate locations of explorations completed for this study are shown on the “Site and Exploration Plan,” Figure 2. A Light Detection and Ranging (LIDAR)-based “Existing Site and Exploration Plan” is included as Figure 3. Interpretive exploration logs and laboratory test results are included in the Appendix. This report is based on the referenced plans. If project plans are changed substantially, we should be allowed to review the recommendations in this report and revise them if necessary. 1.1 Purpose and Scope The purpose of our study is to provide subsurface exploration data and geotechnical engineering recommendations for use during project design. Our study included a review of selected available geologic literature, advancing 20 exploration borings, and performing geologic studies to assess the type, thickness, distribution, and physical properties of the subsurface sediments and shallow groundwater. Geotechnical engineering studies were completed to formulate recommendations for geotechnical critical areas, site preparation, grading, types of suitable foundations and floors, allowable foundation soil bearing pressure, anticipated foundation and floor settlement, drainage considerations, and infiltration feasibility. This report summarizes our fieldwork and offers recommendations based on our present understanding of the project. 1.2 Authorization Our study was authorized by means of a District purchase order. This report has been prepared for the exclusive use of the Renton School District (RSD) for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Project and Site Conditions December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 2 2.0 PROJECT AND SITE DESCRIPTION The subject site includes 11 residential parcels totaling approximately 12.78 acres in total area. Until recently the project site was developed with homes and mature landscaping. The houses were recently demolished and the majority of the landscaping removed. The site includes slope areas highlighted by the City of Renton as potentially meeting criteria for treatment as geotechnical critical areas. Geotechnical critical areas are discussed in detail later in this report. We understand that a wetland has been delineated on the west side and in a low area along Duvall Avenue NE in the northeast corner of the site. The current project concept calls for construction of new elementary school buildings near the center of the project site. A paved parking area is planned south of the school buildings, with hard and soft surface play areas to the north. Wetland areas to the west will be left undisturbed. Construction close to existing grade is expected, without deep excavation or thick structural fill. 3.0 SUBSURFACE EXPLORATION Our field study included advancing a total of 20 exploration borings across the site. Exploration borings EB-1 through EB-8 were advanced on August 22, 2018, EB-9 through EB-14 were advanced on September 27, 2019, and EB-15 through EB-20 were advanced on October 6, 2020. The conclusions and recommendations presented in this report are based on the explorations completed for this study. The number, locations, and depths of our explorations were completed within site and budgetary constraints. Our explorations were approximately located in the field relative to known site features shown on Figures 2 and 3. Interpretive exploration logs and laboratory test results are presented in the Appendix. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. 3.1 Exploration Borings The exploration borings were completed by advancing hollow-stem auger tools with a limited-access track-mounted drill rig. During the drilling process, samples were obtained at generally 2.5- to 5-foot-depth intervals. The exploration borings were continuously observed Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Project and Site Conditions December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 3 and logged by a representative from our firm. The exploration logs presented in the Appendix are based on the field logs, drilling action, and inspection of the samples secured. Disturbed, but representative samples were obtained by using the Standard Penetration Test (SPT) procedure in accordance with ASTM International (ASTM) D-1586. This test and sampling method consists of driving a standard 2-inch, outside-diameter, split-barrel sampler a distance of 18 inches into the soil with a 140-pound hammer free-falling a distance of 30 inches. The number of blows for each 6-inch interval is recorded, and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance (“N”) or blow count. If a total of 50 is recorded within one 6-inch interval, the blow count is recorded as the number of blows for the corresponding number of inches of penetration. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached exploration boring logs. The samples obtained from the split-barrel sampler were classified in the field and representative portions placed in watertight containers. The samples were then transported to our laboratory for further visual classification and laboratory testing. 4.0 SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field explorations accomplished for this study, visual reconnaissance of the site, and review of selected geologic literature. The general distribution of geologic units is shown on the exploration logs. The explorations typically encountered native materials consisting of medium dense grading to very dense lodgement till sediments. Ten exploration borings encountered surficial existing fill to depths of up to approximately 7 feet below the existing ground surface. Two explorations (EB-10 and EB-11) encountered thin layers of fine sand interpreted as Vashon recessional outwash. The northernmost exploration borings (EB-13 and EB-14) terminated at depths of approximately 20.5 to 21.5 feet in stratified sediments that appear to represent lodgement till to advance outwash transition sediments. 4.1 Stratigraphy Grass/Topsoil/Forest Duff A surficial layer of grass and organic topsoil was encountered at the location of each of the exploration locations. This organic layer was approximately 6 inches thick or less at most boring locations, and thicker at three locations. Observed topsoil thickness is shown on the attached subsurface exploration logs. Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Project and Site Conditions December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 4 Due to their high organic content, these materials are not considered suitable for foundation, roadway, or slab-on-grade floor support, or for use in a structural fill. Fill Existing fill was observed in exploration borings EB-3, EB-4, EB-10, EB-12, EB-13, EB-14, EB-15, EB-18, EB-19, and EB-20 to depths of approximately 1.5 to 7 feet below existing ground level. The observed existing fill consists of loose to medium dense silty to very silty sand with varying amounts of gravel and includes some charcoal and other organic material. We anticipate that additional existing fill will be encountered at the locations of former structures and buried utilities. Excavated existing fill material is suitable for reuse in structural fill applications if such reuse is specifically allowed by project plans and specifications, if excessively organic and any other deleterious materials are removed, and moisture content is adjusted to allow compaction to the specified level and to a firm and unyielding condition. Based on our explorations completed for this study, we estimate the observed existing fill was above optimum moisture content for compaction purposes, and therefore may require drying during favorable weather prior to compaction in structural fill applications. Vashon Recessional Outwash Exploration borings EB-10 and EB-11 encountered loose to medium dense sand, with variable amounts of gravel and varying silt content interpreted as Vashon recessional outwash. Vashon recessional outwash was deposited by meltwater streams from a receding glacier and is typically not glacially consolidated. Recessional outwash is suitable for support of paving and lightly-loaded structures with proper preparation. Excavated recessional outwash soils are suitable for reuse in structural fill applications if allowed by project specifications and if adjusted to a suitable moisture content prior to compaction. Vashon Lodgement Till All of our explorations encountered typically medium dense grading to very dense, silty sand with gravel interpreted as Vashon lodgement till. The lodgement till observed in our explorations graded from medium dense to very dense with increasing depth. Lodgement till was deposited at the base of an active ice sheet and was subsequently compacted by the weight of the overlying glacial ice. Lodgement till typically possesses high-strength and low-compressibility attributes that are favorable for support of foundations, floor slabs, and paving with proper preparation. Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Project and Site Conditions December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 5 Lodgement till is silty and moisture-sensitive. In the presence of moisture contents above the optimum moisture content for compaction purposes, lodgement till can be easily disturbed by vehicles and earthwork equipment. Careful management of moisture-sensitive soils, as recommended in this report, will be needed to reduce the potential for disturbance of wet lodgement till soils and costs associated with repairing disturbed soils. Excavated lodgement till sediments are suitable for reuse in structural fill applications if specifically allowed by project specifications, and if moisture conditions are adjusted to allow compaction to a firm and unyielding condition at the specified level. At the time of exploration the lodgement till sediments were observed to be above optimum moisture content for compaction purposes and would require drying during favorable dry site and weather conditions. Vashon Advance Outwash Transition Sediments Two of the exploration borings completed for this study (EB-13 and EB-14) encountered very dense, weakly to moderately bedded sands with variable silt content and trace gravel interpreted as advance outwash transitional sediments. Advance outwash was deposited by meltwater streams from an advancing ice sheet and was subsequently compacted by the overlying glacial ice. The term “transitional” is interpretative and indicates that the sediments represent a gradation zone at the base of the lodgement till and the top of the Vashon advance outwash. Advance outwash is suitable for support of structural loads when prepared as recommended in this report and can be an appropriate receptor for stormwater infiltration under some circumstances. Advance outwash may contain a significant fine-grained fraction and can be sensitive to excess moisture during placement in structural fill applications. Reuse of advance outwash in structural fill applications is feasible if specifically allowed by project specifications and is expected to require drying to achieve moisture contents within 1 to 2 percent of optimum for compaction purposes. 4.2 Regional Geologic and Soil Map Review We reviewed a regional geologic map (J.C. Yount, J.P. Minard, and G.R. Dembroff, 1993, Geologic Map of Surficial Deposits in the Seattle 30’ by 60’ Quadrangle, Washington: U.S. Geological Survey, Open-File Report 93-233, scale 1:100,000). The referenced map indicates that the site is expected to be underlain at shallow depths by Vashon lodgement till. Our on-site explorations and interpretations are generally consistent with the conditions depicted on the referenced published map. Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Project and Site Conditions December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 6 4.3 Hydrology Groundwater was not encountered in any of the explorations completed for this study at the time of exploration. Although not encountered in our explorations, we expect shallow perched groundwater to be present as “interflow” during the wetter season within existing fill, recessional outwash, and the upper, weathered lodgement till sediments. Interflow occurs when surface water infiltrates down through relatively permeable soils such as the fill and recessional outwash sediments, and becomes trapped or “perched” atop a comparatively very low-permeability barrier such as silty unweathered lodgement till. This perched water may travel laterally above less-permeable strata. The duration and quantity of perched seepage will largely depend on the soil grain-size distribution, topography, seasonal precipitation, on- and off-site land usage, and other factors. 4.4 Laboratory Test Results Two laboratory grain-size analyses were performed in accordance with ASTM procedures on representative selected samples collected during our subsurface exploration for this project. The tests were completed on samples of the lodgement till as part of our stormwater infiltration feasibility assessment. The grain-size analyses test results are included in the Appendix. Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Geologic Hazards and Mitigations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 7 II. GEOLOGIC HAZARDS AND MITIGATIONS The following discussion of potential geologic hazards is based on the geologic conditions as observed and discussed herein. 5.0 SLOPE STABILITY HAZARDS AND RECOMMENDED MITIGATION City of Renton critical areas regulations related to steep slopes are contained in Renton Municipal Code (RMC) Section 4-3-050. The City provides an interactive GIS system 1 that shows approximate locations of slopes that meet critical slope definitions included in the RMC. The RMC provides mechanisms for: • Using site-specific survey data in lieu of City GIS maps to determine the presence of regulated slopes. • Establishing prescriptive buffers for regulated slopes, and reducing prescriptive buffers based on site-specific analysis. • Modification of regulated slopes. 5.1 Sensitive Slopes Based on the site survey, the site contains slopes that meet the RMC definition for Sensitive Slopes. The Sensitive Slopes are located along the west side of the site adjacent to mapped wetlands and are interpreted to be slopes that were created during previous earthwork. The RMC does not require a buffer or structure setback for Sensitive Slopes (RMC 4-3-050G). The project as currently proposed may require modification of Sensitive Slopes, which can be allowed under the provisions of RMC 4-3-050J. In our opinion, site grading that is completed in a manner consistent with the recommendations in this report will not result in increased risk of slope instability on or offsite. If construction site Temporary Erosion and Sedimentation Controls (TESCs) are implemented during construction in accordance with local standards of practice, the project as currently proposed will not result in increased risks to the existing wetlands as a result of slope instability or erosion, in our opinion. 5.2 Protected Slopes Based on the site survey, the site does not contain Protected Slopes as defined in RMC 4-3-050G.5.a.ii. 1 https://rp.rentonwa.gov/Html5Public/Index.html?viewer=CORMaps Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Geologic Hazards and Mitigations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 8 6.0 SEISMIC HAZARDS AND RECOMMENDED MITIGATION Earthquakes occur in the Puget Sound Lowland. The majority of these events are small and are usually not felt by people. However, large earthquakes do occur as demonstrated by the most recent 6.8-magnitude event on February 28, 2001 near Olympia, Washington, the 1965 6.5-magnitude event, and the 1949 7.2-magnitude event. The 1949 earthquake appears to have been the largest in this area during recorded history. Evaluation of return rates indicates that an earthquake of the magnitude between 5.5 and 6.0 is likely within a given 20-year period. Generally, there are four types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture, 2) seismically induced landslides, 3) liquefaction, and 4) ground motion. The potential for each of these hazards to adversely impact the proposed project is discussed below. 6.1 Surficial Ground Rupture We reviewed a map of possible geologic fault traces on the Washington State Division of Geology and Earth Resources Interactive Geologic Map. The site is located approximately 0.8 miles south of the Seattle Fault Zone, the closest mapped fault zone to the project. The potential for surface rupture due to seismic faulting is low in our opinion due to the distance from the site to mapped faults. 6.2 Seismically Induced Landslides It is our opinion that the potential risk of damage to the proposed development by seismically induced slope failures is low during a design-level seismic event due to the presence of dense and unsaturated native sediments observed at shallow depths below the site. No detailed quantitative assessment of slope stability was completed, and none is warranted for the project as currently proposed, in our opinion. 6.3 Liquefaction Liquefaction is a process through which unconsolidated soil loses strength as a result of vibrations, such as those which occur during a seismic event. During normal conditions, the weight of the soil is supported by both grain-to-grain contacts and by the fluid pressure within the pore spaces of the soil below the water table. Extreme vibratory shaking can disrupt the grain-to-grain contact, increase the pore pressure, and result in a temporary decrease in soil shear strength. The soil is said to be liquefied when nearly all of the weight of the soil is supported by pore pressure alone. Liquefaction can result in deformation of the sediment and settlement of overlying structures. Areas most susceptible to liquefaction include those areas underlain by non-cohesive silt and sand with low relative densities, accompanied by a shallow water table. Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Geologic Hazards and Mitigations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 9 A review of the City of Renton’s interactive GIS map indicates that a seismic hazard area exists adjacent to the west of the project. Seismic hazard areas are associated with loose, saturated granular soils that may experience liquefaction during a seismic event. Exploration borings on the west part of the project site near the mapped seismic hazard area offsite encountered very dense Vashon lodgement till near the surface. Lodgement till is not susceptible to liquefaction during a seismic event. The site does not contain subsurface conditions that warrant treatment as seismic hazard critical areas, in our opinion. No quantitative liquefaction analysis was completed for this study, and none is warranted for the project as currently proposed, in our opinion. 6.4 Ground Motion/Seismic Site Class (2018 International Building Code) Structural design of the buildings should follow 2018 International Building Code (IBC) standards. We recommend that the project be designed in accordance with Site Class “D” as defined in Table 20.3-1 of American Society of Civil Engineers (ASCE) 7 - Minimum Design Loads for Buildings and Other Structures. As requested, we looked up seismic design values Ss and S1 (IBC 1613.2.1) using the site latitude and longitude and published maps at https://seismicmaps.org/. The published value of Ss is 1.406, and S1 is 0.481. 6.5 Erosion Control The RMC defines a low erosion hazard as an area with soils characterized by the Natural Resource Conservation Service as having slight or moderate erosion potential, and a slope less than 15 percent. A high erosion hazard is defined as having severe or very severe erosion potential, and a slope more than 15 percent. These definitions are incomplete in that the site contains slopes that do not fit either definition. In our opinion the site contains areas that meet the spirit of the definition for low erosion hazard areas. The following recommendations summarize local standards of practice for TESC on construction sites, and are expected to provide adequate mitigation of erosion potential during construction. Project plans should include implementation of temporary erosion controls in accordance with local standards of practice. Control methods should include limiting earthwork to seasonally drier periods, typically April 1 to October 31, use of perimeter silt fences, and straw mulch in exposed areas. Removal of existing vegetation should be limited to those areas that are required to construct the project, and new landscaping and vegetation with equivalent erosion mitigation potential should be established as soon as possible after grading is complete. During construction, surface water should be collected as close as possible to the source to minimize silt entrainment that could require treatment or detention prior to discharge. Timely implementation of permanent drainage control measures should also be a part of the project plans, and will help reduce erosion and generation of silty surface water onsite. Because the site is larger than one acre, testing and reporting of stormwater pH and turbidity will be required during construction. Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Design Recommendations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 10 III. DESIGN RECOMMENDATIONS 7.0 INTRODUCTION Our exploration indicates that from a geotechnical engineering standpoint the proposed school construction project is feasible if the recommendations in this report are implemented. A portion of the site is underlain by existing fill which necessitates remedial preparation prior to constructing new roads and buildings. Observed fill thicknesses at exploration locations are depicted on Figure 2. Existing fill that is expected around former structures and buried utilities will also need to be removed and recompacted at the time of construction. The following report sections provide additional recommendations regarding site preparation, grading, foundations, floor support, drainage, and infiltration feasibility. 8.0 SITE PREPARATION Site preparation of building and paving areas should include removal of all grass, trees, brush, and any other deleterious materials. We recommend that any remaining demolition debris, septic systems, or other similar structures that are discovered be decommissioned and removed in accordance with applicable regulations. Buried utilities should be removed from foundation areas and should be abandoned in place or removed from below planned new paving. Any depressions below planned final grades caused by demolition activities should be backfilled with structural fill, as discussed under the “Structural Fill” section of this report. Existing topsoil and forest duff should be stripped from structural areas. The actual observed in-place depth of grass and topsoil at the exploration locations is presented on the exploration logs in the Appendix. After stripping, remaining roots and stumps should be removed from structural areas. All soils disturbed by stripping and grubbing operations should be recompacted as described below for structural fill. Once stripping is complete, existing fill should be addressed. Existing fill below new buildings should be removed and replaced with structural fill. Below areas of planned paving, existing fill may be left in place if it is free of organic and other deleterious materials, and is compactable to a firm and unyielding condition at 95 percent or more of the modified Proctor maximum dry density (ASTM D-1557). Once excavation to subgrade elevation is complete, the resulting surface should be proof-rolled with a loaded dump truck or other suitable equipment. Any soft, loose, yielding areas or areas exposing excessively organic material should be excavated to exposed suitable bearing soils. The subgrade should then be compacted to at least 95 percent of the modified Proctor maximum dry density, as determined by the ASTM D-1557 test procedure. Structural fill can then be placed to achieve desired grades, if needed. Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Design Recommendations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 11 8.1 Temporary Cut Slopes In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction. For estimating purposes, however, temporary, unsupported cut slopes can be planned at 1.5H:1V (Horizontal:Vertical) in unsaturated existing fill and recessional outwash. Temporary slopes of 1.0H:1V can be planned in unsaturated lodgement till sediments. These slope angles are for areas where groundwater seepage is not present at the faces of the slopes, which may require temporary dewatering in the form of pumped sumps or other measures. If ground or surface water is present when the temporary excavation slopes are exposed, flatter slope angles may be required. As is typical with earthwork operations, some sloughing and raveling may occur, and cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA regulations should be followed at all times. 8.2 Site Disturbance Most of the on-site soils contain fine-grained material, which makes them moisture-sensitive and subject to disturbance when wet. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs, the softened soils should be removed and the area brought to grade with structural fill. 8.3 Winter Construction The existing fill material, as well as the lodgement till and recessional outwash sediments contain substantial silt and are considered highly moisture-sensitive. Soils excavated onsite will likely require drying during favorable dry weather conditions to allow their reuse in structural fill applications. Care should be taken to seal all earthwork areas during mass grading at the end of each workday by grading all surfaces to drain and sealing them with a smooth-drum roller. Stockpiled soils that will be reused in structural fill applications should be covered whenever rain is possible. If winter construction is expected, crushed rock fill could be used to provide construction staging areas where exposed soil is present. The stripped subgrade should be observed by the geotechnical engineer, and should then be covered with a geotextile fabric, such as Mirafi 500X or equivalent. Once the fabric is placed, we recommend using a crushed rock fill layer at least 10 inches thick in areas where construction equipment will be used. 9.0 STORMWATER INFILTRATION FEASIBILITY Our explorations completed for this study encountered existing fill and recessional outwash sediments underlain by dense, silty Vashon lodgement till sediments. Existing fill is not a suitable infiltration receptor due to its variable density, silt, and organic content. Two borings Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Design Recommendations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 12 encountered a thin deposit of recessional outwash at shallow depths. Recessional outwash can be a suitable stormwater infiltration receptor, however the deposits encountered range from 2.5 to 5 feet in thickness and do not appear laterally or vertically extensive enough to support infiltration. Lodgement till is not a suitable infiltration receptor due to its high density and silt content. In our opinion, shallow infiltration at this site using conventional strategies such as infiltrating rain gardens and infiltration vaults is infeasible due to the dense, silty soils at shallow depths across the site. Deep infiltration using strategies such as pit drains or Underground Injection Control (UIC) wells may be feasible, but will require further exploration to determine depth and extent of infiltration receptors at depth. 10.0 STRUCTURAL FILL All references to structural fill in this report refer to subgrade preparation, fill type, placement, and compaction of materials, as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. For backfill of buried utilities in the right-of-way, the backfill should be placed and compacted in accordance with City of Renton codes and standards. After stripping, planned excavation, and any required overexcavation have been performed to the satisfaction of the geotechnical engineer/engineering geologist, the surface of the exposed ground should be recompacted to a firm and unyielding condition. If the subgrade contains too much moisture, adequate recompaction may be difficult or impossible to obtain, and should probably not be attempted. In lieu of recompaction, the area to receive fill should be blanketed with washed rock or quarry spalls to act as a capillary break between the new fill and the wet subgrade. Where the exposed ground remains soft and further overexcavation is impractical, placement of an engineering stabilization fabric may be necessary to prevent contamination of the free-draining layer by silt migration from below. After recompaction of the exposed ground is tested and approved, or a free-draining rock course is laid, structural fill may be placed to attain desired grades. Structural fill is defined as non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts, with each lift being compacted to 95 percent of ASTM D-1557. The top of the compacted fill should extend horizontally outward a minimum distance of 3 feet beyond the locations of the perimeter footings or roadway edges before sloping down at a maximum angle of 2H:1V. The contractor should note that any proposed fill soils should be evaluated by Associated Earth Sciences, Inc. (AESI) prior to their use in fills. This would require that we have a sample of the material at least 72 hours in advance to perform a Proctor test and determine its field compaction standard. Soils in which the amount of fine-grained material (smaller than the No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Design Recommendations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 13 moisture-sensitive. The existing fill and native soils are estimated to contain more than 5 percent fine-grained material. Existing fill and lodgement till soils are estimated to have substantially more than 5 percent fine-grained material. Use of moisture-sensitive soil in structural fills should be limited to favorable dry weather and dry subgrade conditions. Construction equipment traversing the site when the soils are wet can cause considerable disturbance. If fill is placed during wet weather or if proper compaction cannot be obtained, a select, import material consisting of a clean, free-draining gravel and/or sand should be used. Free-draining fill consists of non-organic soil, with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction, and at least 25 percent retained on the No. 4 sieve. Excavated existing fill is suitable for reuse in structural fill applications if such reuse is specifically allowed by project plans and specifications, if excessively organic and any other deleterious materials are removed, and moisture content is adjusted to allow compaction to the specified level and to a firm and unyielding condition. The existing fill and native soils we encountered in our explorations ranged in moisture content from moist to wet. In order to reuse excavated on-site soils in structural fill applications, it will be necessary to moisture-condition wet site soils by aeration and drying during favorable dry weather conditions. Alternatives to drying site soils include using imported granular soils suitable for use in structural fill, or treating wet soils with Portland cement. 11.0 FOUNDATIONS The following sections provide two sets of foundation support geotechnical recommendations, one for building foundations and one for stormwater vault foundations. 11.1 Building Foundations Building areas should be prepared in accordance with the “Site Preparation” and “Structural Fill” sections of this report. Conventional continuous spread footings may be used for building support when founded either directly on the undisturbed, dense to very dense natural sediments, or on compacted structural fill over suitable natural sediments. We recommend that an allowable foundation soil bearing pressure of 3,500 pounds per square foot (psf) be utilized for design purposes, including both dead and live loads. An increase of one-third may be used for short-term wind or seismic loading. All footings must penetrate to the prescribed bearing stratum and no footing should be founded in or above loose, organic, or fill soils. 11.2 Stormwater Vault Foundations We anticipate that the project will include a below-grade, cast-in-place stormwater detention vault. Because the detention vault will be constructed below grade and therefore likely below Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Design Recommendations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 14 any existing weak fill soils, and because the vault has substantial span requirements, a higher allowable foundation soil bearing pressure is appropriate for design of vault foundations. These recommendations are applicable only to the stormwater vault; recommendations presented above should be used for design of building foundations. Conventional continuous spread footings may be used for stormwater vault support when founded on dense to very dense natural sediments. We recommend that an allowable foundation soil bearing pressure of 5,000 psf be utilized for design purposes, including both dead and live loads. An increase of one-third may be used for short-term wind or seismic loading. All footings must penetrate to the prescribed bearing stratum and no footing should be founded in or above loose, organic, or fill soils. 11.3 Conditions, Recommendations, and Settlement Estimate Applicable to All Foundations It should be noted that the area bounded by lines extending downward at 1H:1V from any footing must not intersect another footing or filled area. In addition, a 1.5H:1V line extending down from any footing must not daylight because sloughing or raveling may eventually undermine the footing. Thus, footings should not be placed near the edge of steps or cuts in the bearing soils. Anticipated settlement of footings founded as recommended above should be less than 1 inch with differential settlement one-half of the anticipated total settlement. Most of this movement should occur during initial dead load applications. However, disturbed soil not removed from footing excavations prior to concrete placement could result in increased settlements. All footing areas should be observed by AESI prior to placing concrete to verify that the design bearing capacity of the soils has been attained and that construction conforms to the recommendations contained in this report. Such observation may be required by the City of Renton. A perimeter foundation drain system should be provided as discussed under the “Foundation Drainage Considerations” section of this report. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs the softened soils should be removed and foundations extended down to competent natural soil. Once the base of the excavation is reached, consideration should be given to “armoring” the exposed subgrade with a thin layer of rock to provide a working surface during foundation construction. We recommend a 6-inch layer of crushed rock for this purpose. 11.4 Foundation Drainage Considerations Building and stormwater vault foundations should be provided with foundation drains. Drains should consist of rigid, perforated, polyvinyl chloride (PVC) pipe placed at footing subgrade elevation and surrounded by washed pea gravel. The drains should be constructed with sufficient gradient to allow gravity discharge away from the proposed structures. Roof and Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Design Recommendations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 15 surface runoff should not discharge into footing drain systems, but should be handled by a separate, rigid, tightline drain. In planning, exterior grades adjacent to walls should be sloped downward away from the proposed structures to achieve surface drainage. If it is not possible to place a footing drain at the base of the stormwater vault footings, the vault should be constructed to resist lateral pressure imposed by saturated soils and hydrostatic pressure as recommended in Section 13.0 of this report. 12.0 FLOOR SUPPORT After completion of recommendations in the “Site Preparation” section of this report, floor slabs can be supported on medium dense to very dense native soils or on new structural fill. Floor slabs should be cast atop a minimum of 4 inches of clean, washed, crushed rock, or pea gravel to act as a capillary break. Areas of subgrade that are disturbed (loosened) during construction should be compacted to a non-yielding condition prior to placement of capillary break material. Floor slabs should also be protected from dampness by an impervious moisture barrier at least 10 mils thick. The moisture barrier should be placed between the capillary break material and the concrete slab. 13.0 FOUNDATION WALLS 13.1 Building Foundation Walls The following recommendations may be applied to conventional walls up to 8 feet tall. We should be allowed to offer situation-specific input for taller walls. All backfill behind foundation walls or around foundation units should be placed as per our recommendations for structural fill and as described in this section of the report. Horizontally backfilled walls, which are free to yield laterally at least 0.1 percent of their height, may be designed to resist lateral earth pressure represented by an equivalent fluid equal to 35 pounds per cubic foot (pcf). Fully restrained, horizontally backfilled, rigid walls that cannot yield should be designed for an equivalent fluid of 50 pcf. Walls with sloping backfill up to a maximum gradient of 2H:1V should be designed using an equivalent fluid of 55 pcf for yielding conditions or 75 pcf for fully restrained conditions. If parking areas are adjacent to walls, a surcharge equivalent to 2 feet of soil should be added to the wall height in determining lateral design forces. As required by the 2018 IBC, retaining wall design should include a seismic surcharge pressure in addition to the equivalent fluid pressures presented above. Considering the site soils and the recommended wall backfill materials, we recommend a seismic surcharge pressure of 5H and 10H psf, where H is the wall height in feet for the “active” and “at-rest” loading conditions, respectively. The seismic surcharge should be modeled as a rectangular distribution with the resultant applied at the midpoint of the walls. Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Design Recommendations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 16 The lateral pressures presented above are based on the conditions of a uniform backfill consisting of excavated on-site soils, or imported structural fill compacted to 90 percent of ASTM D-1557. A higher degree of compaction is not recommended, as this will increase the pressure acting on the walls. A lower compaction may result in settlement of the slab-on-grade or other structures supported above the walls. Thus, the compaction level is critical and must be tested by our firm during placement. Surcharges from adjacent footings or heavy construction equipment must be added to the above values. Perimeter footing drains should be provided for all retaining walls, as discussed under the “Drainage Considerations” section of this report. It is imperative that proper drainage be provided so that hydrostatic pressures do not develop against the walls. This would involve installation of a minimum 1-foot-wide blanket drain to within 1 foot of finish grade for the full wall height using imported, washed gravel against the walls. 13.2 Stormwater Vault Foundation Walls Stormwater vaults may be designed in accordance with lateral earth pressure and drainage recommendations as described above for building walls, except as follows: • If it is not possible to place a footing drain at the base of the detention vault, we recommend installing a footing drain as deep as possible depending on footing drain discharge options that are available. • Any location where vault walls extend below drain elevation should be structurally designed for saturated conditions below the elevation of the drain. • Under saturated conditions, active lateral earth pressure should be assumed to be 80 pcf expressed as an equivalent fluid, and at-rest (restrained) lateral earth pressure should be assumed to be 90 pcf. • For detention vault drainage, the use of composite drain mats such as Miradrain is acceptable in lieu of the washed rock drainage blanket described in Section 11.4 of this report. Drainage mats should be continuous with and freely communicate with the footing drain, and should be incorporated and installed in accordance with the manufacturer’s recommendations. 13.3 Passive Resistance and Friction Factors Lateral loads can be resisted by friction between the foundation and the natural soils or supporting structural fill soils, and by passive earth pressure acting on the buried portions of the foundations. The foundations must be backfilled with structural fill and compacted to at least 95 percent of the maximum dry density to achieve the passive resistance provided below. We recommend the following allowable design parameters: Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Design Recommendations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 17 • Passive equivalent fluid = 250 pcf • Coefficient of friction = 0.30 14.0 PAVEMENT RECOMMENDATIONS We anticipate that project plans may include construction of new paved parking lots and access roads. At this time we do not anticipate that new paving will be completed on public streets. If new paving is planned on public streets we should be allowed to make situation-specific paving recommendations. After the area to be paved is stripped, any organic soils are removed, and the soils are recompacted, the area should be proof-rolled with a loaded truck under the observation of AESI. Any soft, wet, organic, or yielding areas should be repaired as recommended during construction. If warranted, engineering stabilization fabric, such as Mirafi 500X (or equivalent), should be placed over the subgrade with the edges overlapped in accordance with the manufacturer’s recommendations. Following subgrade preparation, clean, free-draining structural fill should be placed over the fabric and compacted to 95 percent of ASTM D-1557. Where fabric is exposed, spreading should be performed such that the dozer remains on the fill material and is not allowed to operate on uncovered fabric. When 12 inches of fill has been placed, the fabric should be proof-rolled with a loaded dump truck to pretension the fabric and identify soft spots in the fill. Upon completing the proof-rolling operation, additional structural fill should be placed and compacted to attain desired grades. For driveways and private paving serving passenger cars, we recommend a paving section consisting of 3 inches of Class ½-inch HMA underlain by 4 inches of crushed surfacing base course (CSBC). Alternatively asphalt treated base (ATB) or Class ¾-inch HMA could be used for construction access followed by repair of any construction damage and final surfacing. If this alternative is used, we recommend a minimum of 2 inches of CSBC to serve as a working surface and a minimum of 3 inches of ATB. Final surfacing should consist of 2 inches of Class ½-inch HMA after any construction damage has been repaired. Paving for heavy traffic areas such as bus lanes, fire lanes, and access for garbage and food service trucks should consist of 4 inches of Class ½-inch HMA above 6 inches of crushed rock base. If an ATB section is desired, we recommend a 2-inch-thick working surface of crushed rock, topped by 4 inches of ATB and 3 inches of Class ½-inch HMA. 15.0 PROJECT DESIGN AND CONSTRUCTION MONITORING We are available to provide additional geotechnical consultation as the project design develops and possibly changes from that upon which this report is based. We recommend that AESI perform a geotechnical review of the plans prior to final design completion. In this way, geotechnical recommendations may be properly interpreted and implemented in the design. Updated Subsurface Exploration and Renton School District Elementary School No. 16 Geotechnical Engineering Report Renton, Washington Design Recommendations December 22, 2020 ASSOSCIATED EARTH SCIENCES, INC. BWG/ld - 20180398E002-4 Page 18 We are also available to provide construction monitoring services during construction of the infiltration facilities. The infiltration performance depends on verification of anticipated subsurface conditions, proper site preparation, backfill quality, and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of the current scope of work. If these services are desired, please let us know and we will prepare a cost proposal. We have enjoyed working with you on this study and are confident that these recommendations will aid in the successful completion of your project. If you should have any questions or require further assistance please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington ______________________________ Charles R. Christopher, G.I.T. Senior Staff Geologist ______________________________ Bruce W. Guenzler, L.E.G. Kurt D. Merriman, P.E. Senior Associate Geologist Senior Principal Engineer Attachments: Figure 1: Vicinity Map Figure 2: Site and Exploration Plan Figure 3: Existing Site and Exploration Plan Appendix: Exploration Logs Laboratory Testing Results DATA SOURCES / REFERENCES: USGS: 7.5' SERIES TOPOGRAPHIC MAPS, ESRI/I-CUBED/NGS 2013 KING CO: STREETS, CITY LIMITS, PARCELS, PARKS 3/20 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE VICINITY MAP RENTON SD ELEMENTARY NO. 16 RENTON, WASHINGTON 20180398E002 11/20 1 KING COUNTY KING COUNTY KING COUNTY NEWCASTLE RENTON McKnight Middle School Sierra Heights Elementary School Highlands Elementary School Renton Technical College Honey Dew Elementary School Maplewood Heights Elementary School Hazen High School Apollo Elementary School May Valley Park Maplewood Park Maplewood Park May Creek Park May Creek Park May Creek Park Cougar Mountain Regional Wildland Park 0 2000 Feet PROJ NO. NOTE: BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION DATE:FIGURE:\\kirkfile2\gis\GIS_Projects\aaY2018\180398 Renton SD Chelan Av\mxd\20180398E002 F1 VM_RSD_Chelan.aprx | 20180398E002 F1 VM_RSD_Chelan | 11/9/2020 11:19¥ ¥ ¥ ¬« ¬«900 !(Duvall Ave NENE 12th St DuvallPlNEChelan Ave NEKing County SITE EB-1, 0ft EB-2, 0ftEB-3, 7ft EB-4, 7ft EB-5, 0ft EB-6, 0ft EB-7, 0ft EB-8, 0ft EB-9, 0ft EB-10, 2ft EB-11, 0ft EB-12, 2ft EB-13, 3ft EB-14, 2ft EB-15, 6.5ft EB-16, 0ft EB-17, 0ft EB-18, 3ft EB-19, 5.5ft EB-20, 1.5ft PROJ NO. NOTE: BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION DATE:FIGURE:\\kirkfile2\gis\GIS_Projects\aaY2018\180398 Renton SD Chelan Av\mxd\20180398E002 F2 SP_RSDChelan.aprx | 20180398E002 F2 SP_RSDChelan | 11/9/2020 11:25 AMDATA SOURCES / REFERENCES: HUTTEBALL + OREMUS ARCHITECTURE, NEW ELEMENTARY SCHOOL #16, SITE COORDINATION PLAN, G0.20, 10/21/20 KING CO: PARCELS, 3/20 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE 0 150 Feet SITE AND EXPLORATION PLAN RENTON SD ELEMENTARY NO. 16 RENTON, WASHINGTON 20180398E002 11/20 2 LEGEND SITE EXPLORATION BORING, DEPTH OF FILL NE 10th St Duvall Ave NEAnacortesAveNENE12thSt Chelan Ave NEEB-1 EB-2EB-3 EB-4 EB-5 EB-6 EB-7EB-8 EB-9 EB-10 EB-11 EB-12 EB-13EB-14 EB-15 EB-16 EB-17 EB-18 EB-19 EB-20 400 410 410410 400 430440 4104504104 1 0 4404 5 0 400 400440410 4104604104104504404204 3 0 PROJ NO. NOTE: BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION DATE:FIGURE:\\kirkfile2\gis\GIS_Projects\aaY2018\180398 Renton SD Chelan Av\mxd\20180398E002 F3 Lidar_RSDChelan.aprx | 20180398E002 F3 Lidar_RSDChelan | 11/5/2020 2:45DATA SOURCES / REFERENCES: PSLC: KING COUNTY 2016, GRID CELL SIZE IS 3'. DELIVERY 1 FLOWN 2/24/16 - 3/28/16 CONTOURS FROM LIDAR KING CO: STREETS, PARCELS, 3/20 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE 0 200 Feet EXISTING SITE AND EXPLORATION PLAN RENTON SD ELEMENTARY NO. 16 RENTON, WASHINGTON 20180398E002 11/20 3 LEGEND SITE EXPLORATION BORING PARCEL CONTOUR 10 FT CONTOUR 2 FT APPENDIX Exploration Logs Laboratory Testing Results 14 28 50 35 50/3" 50/1" S-1 S-2 S-3 Bottom of exploration boring at 12.6 feet No groundwater encountered. Grass / Topsoil Vashon Lodgement Till Moist, gray with some oxidation, very silty, gravelly, fine to medium SAND; unsorted (SM). Becomes gray. No recovery due to rock. 1 of 1 NAVD 88 DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples~426 5 10 15 20 EB-1 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202078 5050/3" 5050/1" 19 42 40 22 50/6" 38 29 38 S-1 S-2 S-3 Bottom of exploration boring at 14 feet No groundwater encountered. Grass / Topsoil Vashon Lodgement Till Moist, oxidized gray, very silty, gravelly, fine to medium SAND; unsorted (SM). Becomes gray. Becomes very moist. 1 of 1 NAVD 88 DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples~422 5 10 15 20 EB-2 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202082 5050/6" 67 4 3 5 50/6" 20 26 40 S-1 S-2 S-3 Bottom of exploration boring at 14 feet No groundwater encountered. Grass / Topsoil Fill Slightly moist to dry, brown to dark brown, very silty, fine SAND, trace gravel, trace charcoal and other organics (SM). Moist, grayish brown, silty, fine to medium SAND, some gravel (SM). Vashon Lodgement Till Driller notes hard drilling at 7 feet. Moist, gray, very silty, fine to medium SAND, some gravel; unsorted (SM). Moist, oxidized gray, very silty, fine SAND, trace gravel; unsorted (SM). 1 of 1 NAVD 88 DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples~414 5 10 15 20 EB-3 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202088 5050/6" 66 8 9 14 13 15 17 22 22 26 S-1 S-2 S-3 Bottom of exploration boring at 14 feet No groundwater encountered. Grass / Topsoil Fill Moist, oxidized gray, very silty, fine to medium SAND, some gravel, trace charcoal (SM). Vashon Lodgement Till Driller notes hard drilling at 7 feet. Moist, gray, very silty, fine to medium SAND, some gravel; unsorted (SM). As above. 1 of 1 NAVD 88 DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples~429 5 10 15 20 EB-4 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 20202323 3232 4848 Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 7.5 9.1 4.1 16.3 23.7 39.36 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite Sample Number: EB-1 Depth: 5' Client: Project: Project No:Figure Very Silty Gravelly SAND 1.5 1 .75 .375 #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 92.5 92.5 88.1 83.4 80.2 79.3 73.8 63.0 48.8 42.5 39.3 38.5 np nv SM A-4(0) 12.7521 6.2954 0.3792 0.2641 8-24-18 8-24-18 BN BG 8-22-18 Greene Gasaway RSD Chelan Ave Properties 180398 E001 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 11.3 17.8 5.3 13.4 22.8 29.46 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite Sample Number: EB-7 Depth: 5' Client: Project: Project No:Figure Silty Gravelly SAND 1.5 1 .75 .375 #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 88.7 88.7 77.5 70.9 66.6 65.6 60.8 52.2 39.2 32.7 29.4 28.8 np nv SM A-2-4(0) 27.6933 13.8219 0.7604 0.3864 0.0931 8-24-18 8-24-18 BN BG 8-22-18 Greene Gasaway RSD Chelan Ave Properties 180398 E001 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) 16 19 20 13 17 17 18 25 33 S-1 S-2 S-3 Bottom of exploration boring at 14 feet No groundwater encountered. Grass / Topsoil Vashon Lodgement Till Slightly moist, oxidized gray, very silty, fine SAND, some gravel; unsorted (SM). Becomes moist to very moist, gray. Becomes moist. 1 of 1 NAVD 88 DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples~434 5 10 15 20 EB-5 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 20203939 3434 58 7 10 12 23 50/4" S-1 S-2 Bottom of exploration boring at 10.8 feet No groundwater encountered. Grass / Topsoil Vashon Lodgement Till Moist to very moist, gray with some oxidation, very silty, fine to medium SAND, some gravel; unsorted (SM). Contains trace to some coarse sand (SM). 1 of 1 NAVD 88 DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples~435 5 10 15 20 EB-6 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 20202222 5050/4" 19 34 32 10 19 31 S-1 S-2 Bottom of exploration boring at 11.5 feet No groundwater encountered. Grass / Topsoil Vashon Lodgement Till Moist, gray, silty, gravelly, fine to medium SAND; unsorted (SM). As above. 1 of 1 NAVD 88 DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples~433 5 10 15 20 EB-7 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202066 3364 50/4" 50/1" S-1 S-2 Bottom of exploration boring at 10.1 feet No groundwater encountered. Grass / Topsoil Vashon Lodgement Till Moist, gray, very silty, fine to medium SAND, some gravel; unsorted (SM). Poor recovery due to gravel. 1 of 1 NAVD 88 DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples~414 5 10 15 20 EB-8 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 20205050/4" 5050/1" 2 3 2 12 18 22 14 18 28 50/6" S-1 S-2 S-3 S-4 Bottom of exploration boring at 10.5 feet No groundwater encountered. Sod / Topsoil - ~4 inches Vashon Lodgement Till Moist, orangish brown, silty, fine SAND, trace gravel; frequent organics (charcoal/rootlets) (SM). Moist, orangish gray to brownish gray, silty, fine SAND, trace gravel; unsorted; diamict-like appearance; occasional organics (rootlets) (SM). Moist, brownish gray, silty, fine SAND, trace gravel; rare organics; gravels are subrounded, some broken; unsorted; diamict-like appearance (SM). Driller notes hard drilling. Moist, gray, silty, fine SAND, trace gravel; gravels are fine and subrounded; unsorted; diamict-like appearance (SM). 1 of 1 NAVD 88 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~436 5 10 15 20 EB-9 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202055 4040 4646 5050/6" 4 5 6 2 3 10 40 50/6" 19 20 50/5" 50/5" S-1 S-2 S-3 S-4 S-5 Bottom of exploration boring at 15.4 feet No groundwater encountered. Sod / Topsoil - 4 inches Fill / Duff Moist, orangish gray, silty, fine SAND, trace gravel; occasional organics (charcoal/rootlets); unsorted (SM). Vashon Recessional Outwash Slightly moist, brownish gray, fine SAND, some silt, trace gravel; occasional organics (charcoal/roots) (SP-SM). Vashon Lodgement Till Slightly moist, brownish gray, fine SAND, some silt, trace gravel; rare organics (rootlets); unsorted (SP-SM). Hard drilling/rig chatter at 9 feet. Moist, brownish gray, fine to medium SAND, some silt to silty, trace gravel; weakly stratified zones of silty sand, unsorted, diamict-like and medium sand, some silt (SM/SP-SM). Hard drilling/rig chatter at 12 feet. Moist to very moist, fine to medium SAND, some silt to silty, trace gravel; gravels are subrounded; faintly gradationally stratified (SP-SM/SM). 1 of 1 NAVD 88 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~431 5 10 15 20 EB-10 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 20201111 1313 90 5050/5" 5050/5" 2 2 1 5 8 10 9 9 10 28 50/6" 40 50/5" S-1 S-2 S-3 S-4 S-5 Bottom of exploration boring at 15.9 feet No groundwater encountered. Sod / Topsoil - 4 inches Forest Duff Moist, orangish brown, silty, fine SAND, trace gravel; frequent organics (charcoal/rootlets) (SM). Vashon Recessional Outwash Moist, brownish gray with bands of iron oxide staining, fine to medium SAND, some silt, trace gravel; rare organics (roots); gradationally stratified (SP-SM). As above; gradationally stratified (SP-SM). Vashon Lodgement Till Hard drilling/rig chatter at 7 feet. Moist, gray, silty, fine SAND, some gravel, some medium to coarse sand; unsorted; diamict-like appearance (SM). Hard drilling/rig chatter at 13 feet. As above; gravels are fine to coarse, broken, and weathered; unsorted; diamict-like appearance (SM). 1 of 1 NAVD 88 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~409 5 10 15 20 EB-11 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202033 1818 1919 78 5050/5" 3 4 5 13 29 40 22 29 48 40 50/4" 50/3" S-1 S-2 S-3 S-4 S-5 Bottom of exploration boring at 15.3 feet No groundwater encountered. Fill Moist, light brown to dark brown, silty, fine SAND, some gravel; abundant organics (rootlets/wood debris); poor recovery (SM). Vashon Lodgement Till Slightly moist to moist, brownish gray with mottled iron oxide staining, silty, fine SAND, some gravel; gravels are fine to coarse, weathered, and broken; unsorted; diamict-like appearance (SM). As above; less iron oxide mottling; some coarse sand; broken gravels throughout (SM). Hard drilling/rig chatter at 7 feet. Slightly moist, brownish gray, silty, fine SAND, some gravel; section (~2 inches thick) of broken gravel (SM). Hard drilling at 11.5 feet. Rig chatter at 12.5 feet. Moist, brownish gray, silty, fine SAND, some gravel; broken gravel throughout; unsorted; diamict like (SM). 1 of 1 NAVD 88 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~425 5 10 15 20 EB-12 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202099 69 77 5050/4" 5050/3" 3 2 1 2 9 15 8 11 16 10 15 16 50/6" 40 50/5" S-1 S-2 S-3 S-4 S-5 S-6 Bottom of exploration boring at 20.9 feet No groundwater encountered. Fill Moist, orangish brown to dark brown, silty, fine to medium SAND, some gravel; frequent organics (charcoal/rootlets) (SM). Upper 6 inches: very moist, brown to grayish brown, silty, fine to medium SAND, some gravel (SM). Vashon Lodgement Till Lower 6 inches: moist, brownish gray with bands of iron oxide staining, silty, fine SAND, trace to some gravel; unsorted; diamict-like (SM), Upper 6 inches: as above (SM). Lower 6 inches: becomes moist, gray to greenish gray, silty, fine SAND, some gravel; gravels are fine to coarse, weathered, and broken (SM). Upper 4 inches: as above; moderate to strong organic/petrochemical odor (SM). Moist, brownish gray with mottled iron oxide staining, silty, medium SAND, some gravel, some purple gravel (rhyolite?); unsorted; diamict-like (SM). Hard drilling/rig chatter at 12.5 feet. Moist, brownish gray, silty, fine to medium SAND, some gravel; unsorted; diamict-like appearance; gravels are subrounded, some broken, and weathered (SM). Upper 6 in: moist, brownish gray, interbedded silty, fine SAND (SM) and medium SAND, trace silt (SP). At 20.5 ft: Vashon Lodgement Till / Vashon Advance Outwash ? - Lower 6 in: moist to very moist, brownish gray, fine to medium SAND, some silt, trace gravel (SP-SM); moderately bedded with occasional interbeds (~1/2 inch thick) of silty fine sand (SM). 1 of 1 NAVD 88 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~424 5 10 15 20 EB-13 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202033 2424 2727 3131 5050/6" 5050/5" 3 2 2 10 20 22 9 15 23 40 50/4" 50/6" 17 13 40 S-1 S-2 S-3 S-4 S-5 S-6 Bottom of exploration boring at 21.5 feet No groundwater encountered. Sod / Topsoil - 4 inches Fill Moist, orangish brown, silty, fine SAND, trace gravel; frequent organics (charcoal/rootlets) (SM). Vashon Lodgement Till Slightly moist, brownish gray with mottled iron oxide staining, silty, fine SAND, some gravel; massive; unsorted; gravels are fine to coarse, broken, and weathered (SM). Hard drilling at 4 feet. Moist, brownish gray with mottled iron oxide staining, silty, fine SAND, some gravel; unsorted; diamict-like; gravels are broken and weathered (SM). Slightly moist to moist, brownish gray, silty, fine to medium SAND, some gravel; gravels are broken and weathered; section (~2 inches thick) of broken gravel; less silt and moisture with depth (SM). Hard drilling/rig chatter at 11 feet. Moist, brownish gray, silty, fine to medium SAND, trace to some gravel; gravels are broken throughout; unsorted; diamict-like appearance (SM). Hard drilling/rig chatter at 16 feet. Upper 5 inches: moist, brownish gray, silty, fine SAND, trace gravel; unsorted; diamict-like (SM). At 20.4 ft: Vashon Advance Outwash / Vashon Lodgement Till ? - Becomes moist to very moist, brownish gray, interbedded, silty, fine SAND (SM) and fine to medium SAND, some silt (SP-SM); moderately bedded in layers (~1/2 inch thick); higher moisture in less silty interbeds. 1 of 1 NAVD 88 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~421 5 10 15 20 EB-14 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202044 4242 3838 5050/4" 5050/6" 53 3 4 4 4 15 13 5 6 8 3 41 50/3" 27 47 50/5" 15 17 32 S-1 S-2 S-3 S-4 S-5 S-6 Bottom of exploration boring at 16.5 feet No groundwater encountered. Topsoil - 6 inches Moist, dark brown, sandy, SILT; frequent rootlets/organics (ML). Fill Lower 6 inches: moist, orangish brown with moderate oxidation, mostly fine to medium SAND, some silt; occasional mica, charcoal, and rootlets; discontinuous lens of dark brown, sandy, silt (SP-ML). Upper 6 inches: as above; becomes heavily oxidized; silty; moderate fine organics/rootlets (SM). Lower 12 inches: moist, grayish brown with slight to moderate oxidation staining, silty, fine SAND, some gravel; one broken gravel in sampler; unsorted (SM). Moist to very moist, brownish gray, silty, fine SAND, some gravel; scattered clasts of brown, sandy, silt with moderate oxidation; unsorted (SM-ML). Vashon Lodgement Till Increased drilling difficulty at 6.5 feet. Moist, brownish gray with slight oxidation, silty, fine to medium SAND, some gravel; becomes very moist within sandier zones; unsorted (SM). As above; moist. As above. 1 of 1 NAVD 88 CRC2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~433 5 10 15 20 EB-15 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 10/6/20,10/6/20 Logged by: Shelby Tube Sample 140# / 30" Advance Drill Tech / D50 Mobile Track Rig Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202088 2828 1414 5050/3" 5050/5" 4949 4 5 14 5 10 18 15 41 35 41 50/5" 50/6" S-1 S-2 S-3 S-4 S-5 Bottom of exploration boring at 10.5 feet No groundwater encountered. Topsoil - 12 inches Moist to very moist, dark brown,sandy, SILT; frequent fine organic debris, roots, and rootlets (ML). Vashon Lodgement Till Lower 12 inches: moist, brown with moderate oxidation, silty, fine SAND, trace gravel; occasional rootlets (SM). Grinding and increased drilling difficulty at 2 feet. Moist, grayish brown with slight oxidation, silty, fine to medium SAND, some gravel to gravelly; contains sandier zones; unsorted (SM). As above; becomes brownish gray; lack of sandier zones; blowcounts are slightly overstated (SM). Bouncing on rock at 5 feet. Moist, brownish gray, silty, fine to medium SAND, some gravel; unsorted (SM). As above. 1 of 1 NAVD 88 CRC2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~428 5 10 15 20 EB-16 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 10/6/20,10/6/20 Logged by: Shelby Tube Sample 140# / 30" Advance Drill Tech / D50 Mobile Track Rig Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 20201919 2828 76 5050/5" 5050/6" 3 4 5 10 18 17 11 38 48 22 32 34 50/3" 50 36 36 S-1 S-2 S-3 S-4 S-5 S-6 Bottom of exploration boring at 16.5 feet No groundwater encountered. Topsoil - 6 inches Vashon Lodgement Till Lower 6 inches: moist, brown with moderate to heavy oxidation, silty, fine to medium SAND, trace gravel; moderate rootlets/charcoal (SM). Drilling difficulty and grinding increases at 1.5 feet. Moist, grayish brown with slight to moderate oxidation, silty, fine to medium SAND, trace gravel; unsorted (SM). Drilling difficulty increases. Moist, brownish gray with slight oxidation, silty, fine to medium SAND, some gravel; unsorted; broken gravel within sampler; blowcounts are slightly overstated (SM). As above. As above; poor recovery; bouncing on rock; blowcounts overstated. As above; broken gravel within sampler; blowcounts slightly overstated. 1 of 1 NAVD 88 CRC2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~428 5 10 15 20 EB-17 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 10/6/20,10/6/20 Logged by: Shelby Tube Sample 140# / 30" Advance Drill Tech / D50 Mobile Track Rig Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202099 2525 86 66 5050/3" 72 3 4 5 11 13 36 19 21 31 12 44 50/5" 43 50/5" 15 50/5" S-1 S-2 S-3 S-4 S-5 S-6 Bottom of exploration boring at 16 feet No groundwater encountered. Topsoil - 6 inches Fill Lower 6 inches: moist, brown with slight oxidation, silty, fine SAND; occasional rootlets/charcoal (SM). Upper 6 inches: as above (SM). Vashon Lodgement Till Lower 12 inches: moist, grayish brown, silty, fine to medium SAND, trace gravel; occasional rootlets; unsorted (SM). Drilling difficulty increases at 4.5 feet. Moist, brownish gray with slight oxidation, silty, fine to medium SAND, some gravel; broken gravel within sampler; unsorted (SM). As above; lack of slight oxidation (SM). As above; pounding on rock; blowcounts overstated. As above; contains sandier zones; ranges to very moist within sandier zones. 1 of 1 NAVD 88 CRC2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~431 5 10 15 20 EB-18 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 10/6/20,10/6/20 Logged by: Shelby Tube Sample 140# / 30" Advance Drill Tech / D50 Mobile Track Rig Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202099 4949 52 5050/5" 5050/5" 5050/5" 3 5 8 4 4 10 3 18 50/6" 17 28 50/6" 36 50/6" S-1 S-2 S-3 S-4 S-5 Bottom of exploration boring at 11 feet No groundwater encountered. Topsoil - 2 inches Fill Lower 10 inches: moist, brown, silty, fine to medium SAND, some gravel; moderate rootlets/fine organic debris/charcoal; chaotic structure (SM). As above; poor recovery/brick debris (SM). Upper 6 inches: as above. Vashon Lodgement Till Lower 12 inches: moist, grayish light brown with slight oxidation, silty, fine to medium SAND, some gravel; broken gravel within sampler; unsorted (SM). Moist, brownish gray, silty, fine to medium SAND, some gravel; broken gravel within sampler; unsorted (SM). As above. 1 of 1 NAVD 88 CRC2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~430 5 10 15 20 EB-19 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 10/6/20,10/6/20 Logged by: Shelby Tube Sample 140# / 30" Advance Drill Tech / D50 Mobile Track Rig Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 20201313 1414 5050/6" 5050/6" 5050/6" 2 2 2 5 11 9 8 11 18 48 41 50/6" 50/3" S-1 S-2 S-3 S-4 S-5 Bottom of exploration boring at 10.5 feet No groundwater encountered. Topsoil - 2 inches Fill Lower 10 inches: moist, brown to dark brown with moderate oxidation, silty, fine to medium SAND; moderate roots, rootlets, and charcoal; chaotic structure (SM). Vashon Lodgement Till Moist, grayish brown with moderate oxidation staining, silty, fine SAND; unsorted (SM). Increased drilling difficulty. Moist, grayish brown with slight oxidation, silty, fine to medium SAND, some gravel; unsorted (SM). Moist, brownish gray, silty, fine to medium SAND, some gravel; unsorted (SM). No recovery; bouncing on rock. 1 of 1 NAVD 88 CRC2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples~434 5 10 15 20 EB-20 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Renton School District Elementary School No. 16 M - Moisture Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)S T Exploration Number 20180398E002 10/6/20,10/6/20 Logged by: Shelby Tube Sample 140# / 30" Advance Drill Tech / D50 Mobile Track Rig Well Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST):AESIBOR 20180398E002.GPJ November 18, 202044 2020 2929 5050/6" 5050/3"