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HomeMy WebLinkAboutRS_Geotechnical_Report_200309.pdfassociated earth sciences incorporated Associated Earth Sciences, Inc. 911 5th Avenue Kirkland, WA 98033 P (425) 827 7701 Updated Subsurface Exploration and Geotechnical Feasibility Study RENTON SCHOOL DISTRICT CHELAN AVENUE PROPERTIES Renton, Washington Prepared For: RENTON SCHOOL DISTRICT C/O GREENE GASAWAY ARCHITECTS, PLLC October 15, 2019 Project No. 180398E001 DRAFT Kirkland Office | 911 Fifth Avenue | Kirkland, WA 98033 P | 425.827.7701 Mount Vernon Office | 508 S. Second Street, Suite 101 | Mount Vernon, WA 98273 P | 425.827.7701 Tacoma Office | 1552 Commerce Street, Suite 102 | Tacoma, WA 98402 P | 253.722.2992 www.aesgeo.com October 15, 2019 Project No. 180398E001 Renton School District c/o Greene Gasaway Architects, PLLC P.O. Box 4158 Federal Way, Washington 98063 Attention: Mr. Calvin Gasaway Subject: Updated Subsurface Exploration and Geotechnical Feasibility Study Renton School District Chelan Avenue Properties Renton, Washington Dear Mr. Gasaway: We are pleased to present this updated preliminary geotechnical feasibility report for the referenced project. This report summarizes the results of our subsurface exploration and geotechnical engineering feasibility study for the multi-parcel assemblage identified as the “Renton School District Chelan Avenue Properties” located in Renton, Washington, and offers preliminary recommendations for future development of the subject site. Detailed project plans have not been prepared, and therefore our recommendations are preliminary. An earlier draft of this report was prepared, dated August 31, 2018. This updated report incorporates data from six additional recently completed exploration borings. 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 180398E001-3 Projects\20180398\KE\WP DRAFT UPDATED SUBSURFACE EXPLORATION AND GEOTECHNICAL FEASIBILITY STUDY RENTON SCHOOL DISTRICT CHELAN AVENUE PROPERTIES Renton, Washington Prepared for: Renton School District c/o Greene Gasaway Architects, PLLC P.O. Box 4158 Federal Way, Washington 98063 Prepared by: Associated Earth Sciences, Inc. 911 5th Avenue Kirkland, Washington 98033 425-827-7701 October 15, 2019 Project No. 180398E001 DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Project and Site Conditions October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 1 I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report summarizes the results of our subsurface exploration and geotechnical engineering feasibility study for the multi-parcel assemblage identified as the “Renton School District Chelan Avenue Properties” located in Renton, Washington. Our recommendations are preliminary in that the project is still in conceptual planning. Recommendations in this report are based on email correspondence from Greene Gasaway Architects, PLLC (Gasaway). We were also provided with a site survey prepared in support of an earlier development proposal that was not constructed. The site location is shown on the “Vicinity Map,” Figure 1. The approximate locations of explorations completed for this study are shown on Figure 2. Interpretive exploration logs and laboratory test results are included in the Appendix. 1.1 Purpose and Scope The purpose of this general site feasibility study was to provide subsurface data to be utilized in the future development of the subject site. Our study included a review of selected available geologic literature, advancing 14 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 preliminary recommendations for 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 preliminary recommendations based on our present understanding of the project. We recommend that we be allowed to review the recommendations presented in this report and revise them, if needed, when the project has been designed. 1.2 Authorization Our study was accomplished in general accordance with our scope of work and cost proposal dated August 8, 2018. This report has been prepared for the exclusive use of the Renton School District (RSD), c/o Greene Gasaway and their agents, 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. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Project and Site Conditions October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 2 2.0 PROJECT AND SITE DESCRIPTION The subject site includes 15 residential parcels and two City of Renton Rights-of-Way totaling approximately 12.78 acres in total area. The parcels are currently developed with homes and mature landscaping. Based on our review of King County geographic information systems (GIS) mapping (iMAP), overall topography slopes gently to the west-southwest with overall vertical relief on the order of approximately 30 feet across the site. King County mapping indicates there are no mapped geotechnical critical areas on any of the parcels. At the time this report was prepared, this project was in the feasibility study phase and no specific project had been proposed. We anticipate that the site would be redeveloped by removing existing houses and constructing a new school. Construction close to existing grade is expected, without deep excavation or thick structural fill. 3.0 SUBSURFACE EXPLORATION Our field study included advancing fourteen exploration borings across the site. 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. The locations of the exploration borings were measured in the field from landmarks visible on the aerial photograph used as a basis for Figure 2. 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 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 American Society for Testing and Materials (ASTM) D-1586. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Project and Site Conditions October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 3 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. Five exploration borings encountered surficial existing fill to thicknesses of up to approximately 7 feet. Two explorations (EB-10 and EB-11) found shallow Vashon recessional outwash sediments ranging in thickness from approximately 2.5 to 5 feet thick. The northernmost exploration borings (EB-13 and EB-14) terminated in potential lodgement till and advance outwash transition sediments at depths of approximately 20.5 to 21.5 feet. One boring, boring EB-13, encountered soils with hydrocarbon odors between approximately 2 and 10 feet below the ground surface. No fuel tank or other lightly hydrocarbon source was noted. No quantitative analytical testing was completed. We reviewed a published geologic map of the project, Geologic Map of Surficial Deposits in the Seattle 30’ by 60’ Quadrangle, Washington, by J.C. Yount, J.P. Minard, and G.R. Dembroff, 1993. 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. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Project and Site Conditions October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 4 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 in thickness. At two exploration borings (EB-11 and EB-12), weathered organic soils interpreted as forest duff extended in depth to approximately 2 feet below existing ground surface. Observed topsoil thickness is shown on the attached subsurface exploration logs. 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-13, and EB-14 to depths of approximately 2 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 existing structures and buried utilities. Septic systems may also be present onsite and existing fill is expected in any such areas. 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. The Vashon recessional outwash unit was deposited by meltwater streams that emanated from the retreat of the glacial ice and outburst floods of proglacial lakes during the latter portion of the Vashon Stade of the Fraser Glaciation approximately 13,000 years ago. 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. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Project and Site Conditions October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 5 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. 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, we anticipate that most of the lodgement till sediments were 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 used to indicate that the material may be near the till to advance outwash geologic contact. 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 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 DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Project and Site Conditions October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 6 outwash sediments, and becomes trapped or “perched” atop a comparatively very low- permeability barrier such as silty unweathered lodgement till. This water may travel laterally and typically will follow the ground surface topography. The duration and quantity of interflow seepage will largely depend on the soil grain-size distribution, topography, seasonal precipitation, on- and off-site land usage, and other factors. 4.3 Laboratory Test Results Two laboratory grain-size analyses were performed in accordance with the ASTM D-422 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. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Geologic Hazards and Mitigations October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP 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 Based our review of King County GIS data and our recent visual reconnaissance of the site, it does not appear that any slopes onsite meet Renton Municipal Code (RMC) definitions for treatment as Landslide Hazard Areas as defined in RMC Section 4-3-050. No detailed assessment of slope stability was prepared as part of this report and none is warranted, in our opinion. 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 evidenced 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 and is not close to mapped potential 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 lack of steep slopes in the immediate project area. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Geologic Hazards and Mitigations October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 8 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. Our explorations suggest that the potential risk of damage to the proposed development by liquefaction is low, due to the dense, glacially consolidated lodgement till sediments observed at shallow depths and the absence of shallow groundwater. 6.4 Ground Motion/Seismic Site Class (2015 International Building Code) Structural design of the buildings should follow 2015 International Building Code (IBC) standards. We recommend that the project be designed in accordance with Site Class “C” as defined in IBC Table 20.3-1 of American Society of Civil Engineers (ASCE) 7 – Minimum Design Loads for Buildings and Other Structures. 6.5 Erosion Control 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. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Preliminary Design Recommendations October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 9 III. PRELIMINARY DESIGN RECOMMENDATIONS 7.0 INTRODUCTION Our exploration indicates that, from a geotechnical engineering standpoint, the site is feasible for future development provided the recommendations contained herein are properly followed. 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 existing structures and buried utilities to be demolished 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, debris, and any other deleterious materials. All existing fill beneath planned foundation areas should be removed. We recommend that any existing septic systems, wells, heating oil storage tanks, and other similar structures be decommissioned and removed in accordance with applicable regulations. Existing foundations and any other buried structures should be removed from below planned foundation areas. 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 as needed 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 DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Preliminary Design Recommendations October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 10 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. 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. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Preliminary Design Recommendations October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 11 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 encountered 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 silt content. In our opinion, shallow infiltration at this site using conventional strategies such as 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. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Preliminary Design Recommendations October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 12 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 moisture-sensitive. The existing fill and native soils are estimated to contain more than 5 percent fine-grained material. Existing fill and lodgment 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 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. Foundation areas should be deepened, if necessary, to expose sediments suitable for the support of the recommended bearing pressures. 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. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Preliminary Design Recommendations October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 13 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 on the dense to very dense natural sediments 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 or mat 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 “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. 11.1 Drainage Considerations Foundations should be provided with foundation drains. Drains should consist of rigid, perforated, polyvinyl chloride (PVC) pipe surrounded by washed pea gravel. The drains should be constructed with sufficient gradient to allow gravity discharge away from the proposed buildings. Roof and surface runoff should not discharge into the footing drain system, 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. 12.0 FLOOR SUPPORT 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 DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Preliminary Design Recommendations October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 14 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 The following preliminary 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 2015 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. 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. DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Preliminary Design Recommendations October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 15 13.1 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: •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 DRAFT Updated Subsurface Exploration and Renton School District Chelan Avenue Properties Geotechnical Feasibility Study Renton, Washington Preliminary Design Recommendations October 15, 2019 ASSOSCIATED EARTH SCIENCES, INC. ALG/ld - 180398E001-3 - Projects\20180398\KE\WP Page 16 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 Our report is preliminary since no specific project had been proposed at the time this report was prepared. We recommend that we be allowed to review project plans when they are completed and to revise the recommendations presented in this report as needed. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundation system depends on proper site preparation 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 our currently approved scope of work. 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 ______________________________ Angela L. Gelfer, G.I.T. Staff Geologist ______________________________ Bruce W. Guenzler, L.E.G. Kurt D. Merriman, P.E. Associate Geologist Senior Principal Engineer Attachments: Figure 1: Vicinity Map Figure 2: Site and Exploration Plan Appendix: Exploration Logs Laboratory Testing Results DRAFT NEWCASTLE RENTON May ValleyPark MaplewoodPark MayCreekPark Cougar MountainRegionalWildland Park KING COUNTY KING COUNTY KING COUNTY Hazen HighSchool McKnightMiddleSchool ApolloElementarySchool Sierra HeightsElementarySchool HighlandsElementarySchool RentonTechnicalCollege Honey DewElementarySchool Maplewood HeightsElementary School Copyright:© 2013 National Geographic Society, i-cubed 0 20001000 FEET ± NOTE: BLACK AND WHITEREPRODUCTION OF THIS COLORORIGINAL MAY REDUCE ITSEFFECTIVENESS AND LEAD TOINCORRECT INTERPRETATION VICINITY MAP PROJ NO. DATE: FIGURE:180398E001 10/19 1Document Path: G:\GIS_Projects\aaY2018\VM\180398E001 F1 VM_RSDChelanAveProps.mxdDATA SOURCES / REFERENCES:USGS: 7.5' SERIES TOPOGRAPHIC MAPS, ESRI/I-CUBED/NGS 2013KING CO: STREETS, PARCELS, CITY LIMITS 1/18 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE KitsapCounty Snohomish County Pierce County King County DuvallAveNENE 1 2t h S t ChelanAveNE¬«900 SITE RSD CHELAN AVENUE PROPERTIESRENTON, WASHINGTONDRAFT !( !(!(!( !( !( !( !( !( !( !( !( !( !( NE 10TH ST DUVALLAVENECHELANAVENEANACORTESAVENENE 12TH ST NE 11TH ST NE 12TH ST EB-1, 0ft EB-2, 0ftEB-3, 7ft EB-4, 7ft EB-5, 0ft EB-6, 0ft EB-7, 0ftEB-8, 0ft EB-9, 0ft EB-10, 2ft EB-11, 0ft EB-12, 2ft EB-13, 2.5ftEB-14, 2ft 465460445430425420415455450440435405 400 415410400395410450440440410410400400Pictometry International Corp. 0 200100 FEET ± NOTE: BLACK AND WHITEREPRODUCTION OF THIS COLORORIGINAL MAY REDUCE ITSEFFECTIVENESS AND LEAD TOINCORRECT INTERPRETATION SITE ANDEXPLORATION PLANRSD CHELAN AVENUE PROPERTIESRENTON, WASHINGTON PROJ NO. DATE: FIGURE:180398E001 10/19 2Document Path: G:\GIS_Projects\aaY2018\180398 Renton SD Chelan Av\mxd\180398E001 F2 ESP_RSD_ChelanAv.mxdDATA SOURCES / REFERENCES:KING CO: STREETS, PARCELS 1/18AERIAL: PICTOMETRY INT. 2015PSLC: KING COUNTY 2016, GRID CELL SIZE IS 3'.DELIVERY 1 FLOWN 2/24/16 - 3/28/16CONTOURS FROM LIDARLOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE King County SITE !(EXPLORATION BORING, DEPTH OFEXISTING FILL CONTOUR 5 FT HazenHighSchool DRAFT APPENDIX Exploration Logs Laboratory Testing Results DRAFT 14 28 50 35 50/3" 50/1" 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. S-1 S-2 S-3 1 of 1 N/A DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well~428 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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 201978 5050/3" 5050/1"DRAFT 19 42 40 22 50/6" 38 29 38 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. S-1 S-2 S-3 1 of 1 N/A DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well~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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 201982 5050/6" 67 DRAFT 4 3 5 50/6" 20 26 40 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). S-1 S-2 S-3 1 of 1 N/A DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well~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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 201988 5050/6" 66 DRAFT 8 9 14 13 15 17 22 22 26 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. S-1 S-2 S-3 1 of 1 N/A DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well~428 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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 20192323 3232 4848DRAFT 16 19 20 13 17 17 18 25 33 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. S-1 S-2 S-3 1 of 1 N/A DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well~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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 20193939 3434 58DRAFT 7 10 12 23 50/4" 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). S-1 S-2 1 of 1 N/A DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well~438 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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 20192222 5050/4"DRAFT 19 34 32 10 19 31 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. S-1 S-2 1 of 1 N/A DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well~434 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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 201966 3364 DRAFT 50/4" 50/1" 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. S-1 S-2 1 of 1 N/A DV2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name CJKWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 5 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 8/22/18,8/22/18 Logged by: Shelby Tube Sample 140# / 30" Geologic Drill / Mini Track Well~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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 20195050/4" 5050/1"DRAFT 2 3 2 12 18 22 14 18 28 50/6" 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). S-1 S-2 S-3 S-4 1 of 1 NAV 1983 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well~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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 201955 4040 4646 5050/6"DRAFT 4 5 6 2 3 10 40 50/6" 19 20 50/5" 50/5" 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). S-1 S-2 S-3 S-4 S-5 1 of 1 NAV 1983 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well~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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 20191111 1313 90 5050/5" 5050/5"DRAFT 2 2 1 5 8 10 9 9 10 28 50/6" 40 50/5" 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). S-1 S-2 S-3 S-4 S-5 1 of 1 NAV 1983 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well~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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 201933 1818 1919 78 5050/5"DRAFT 3 4 5 13 29 40 22 29 48 40 50/4" 50/3" 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). S-1 S-2 S-3 S-4 S-5 1 of 1 NAV 1983 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well~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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 201999 69 77 5050/4" 5050/3"DRAFT 3 2 1 2 9 15 8 11 16 10 15 16 50/6" 40 50/5" 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; moderate organic/petrochemical odor (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; moderate organic/petrochemical odor (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; some gravels are broken/weathered (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). S-1 S-2 S-3 S-4 S-5 S-6 1 of 1 NAV 1983 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well~423 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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 201933 2424 2727 3131 5050/6" 5050/5"DRAFT 3 2 2 10 20 22 9 15 23 40 50/4" 50/6" 17 13 40 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. S-1 S-2 S-3 S-4 S-5 S-6 1 of 1 NAV 1983 ALG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 8 inches 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 180398E001 9/27/19,9/27/19 Logged by: Shelby Tube Sample 140# / 30" Boretec / Rubber-Track Volvo EC55C HSA Well~420 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) RSD Chelan Avenue Properties M - Moisture AESIBOR 180398.GPJ October 15, 201944 4242 3838 5050/4" 5050/6" 53DRAFT 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)DRAFT 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)DRAFT