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HomeMy WebLinkAbout26-Geotechnical Report Kirkland Office | 911 Fifth Avenue | Kirkland, WA 98033 P | 425.827.7701 F| 425.827.5424 Everett Office | 2911 ½ Hewitt Avenue, Suite 2 | Everett, WA 98201 P | 425.259.0522 F | 425.827.5424 Tacoma Office | 1552 Commerce Street, Suite 102 | Tacoma, WA 98402 P | 253.722.2992 F | 253.722.2993 www.aesgeo.com December 16, 2016 Project No. EE160674A Mark Seek 15233 Manion Way NE Duvall, Washington 98019 Subject: Subsurface Exploration and Geotechnical Engineering Report Bethany Corner 16451 111th Avenue SE Renton, Washington Dear Mr. Seek: As requested, this letter-report presents the results of our subsurface exploration and geotechnical engineering services for the above-referenced project. Our understanding of the project is based on our discussions with you and a review of the proposed site plan prepared by DR Strong Consulting Engineers Inc. dated November 29, 2016. Written authorization to proceed with this study was granted by Mark Seek. Our study was accomplished in general accordance with our scope of work as presented in a signed contract dated December 8, 2016. This letter-report has been prepared for the exclusive use of Mr. Mark Seek and his 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 practices in effect, in this area at the time our letter-report was prepared. Our observations, findings, and opinions are a means to identify and reduce the inherent risks to the owner. No other warranty, express or implied, is made. SITE AND PROJECT DESCRIPTION The project site is located on two currently developed parcels with addresses of 16433 and 16451 111th Avenue Northwest in Renton, Washington. The parcels are combined for the project and create a fairly square property with a total area of about 1.8 acres. The site location is shown on the “Vicinity Map,” Figure 1. The parcel is currently developed with residential construction and is vegetated typical residential landscaping. Site topography generally slopes downward towards the west from 111th Avenue NW to the homes and is relatively level for the remainder of the lot area Bethany Corner Subsurface Exploration Renton, Washington and Geotechnical Engineering Report December 16, 2016 ASSOCIATED EARTH SCIENCES, INC. MM/pc - EE160525A4 - Projects\20160525\EE\WP Page 2 to the west. The north side of the site gradually slopes up to the adjacent lot. The total topographic difference on the site is about 6 to 8 feet We understand, the project will consist of the construction of nine single-family residential lots and a drainage tract. Access to the lots will be from the east by a single road with five lots on the north side and four on the south. Within the drainage tract at the southeast corner of the plat we understand there will be a storm water vault. Preliminary planning indicates that the bottom of the vault will be about 12 to 14 feet below the existing grade. SUBSURFACE EXPLORATION AND CONDITIONS Our subsurface exploration completed for this project included the excavation of five exploration pits dug on December 14, 2016. The conclusions and recommendations presented in this letter-report are based on the explorations completed for this study. The locations and depths of the explorations were completed within site and budget constraints. The approximate locations of explorations completed for this study are presented on the “Site and Exploration Plan,” Figure 2. Copies of the subsurface exploration logs are also attached with this letter-report in the Appendix. The exploration pits were excavated using a tracked mini excavator provided by the client. The pits permitted direct, visual observation of subsurface conditions. Materials encountered in the exploration pits were studied and classified in the field by an experienced geotechnical engineer from our firm. All exploration pits were backfilled after examination and logging. Selected samples were then transported to our laboratory for further visual classification. Our explorations generally encountered shallow, native lodgement till soils and fill placed over the lodgement till, for the full depth of the exploration to a depth of about 6 to 8 feet. The encountered lodgement till was weathered near the surface consisting of medium dense, moist, tan, silty sand with gravel and was unsorted. At depths of 2 to 3 feet below the surface the lodgement till graded to unweathered till that consisted of dense, gray, silty fine sand with gravel and was unsorted. In the vicinity of the vault we extended a pit to a depth of 14 feet. At this depth the till was underlain by a hard silt described as pre Vashon silt. On the central to west end of the site we encountered fill soils (soil not naturally placed) to a maximum depth of about 6 feet. The fill consisted of a mixture of sand silt and gravel mixed with trace amounts of debris and pockets of organics. Lodgement till was deposited at the base of an active continental glacier during the Vashon Stade of the Fraser Glaciation approximately 12,500 to 15,000 years ago. The till was compacted by the weight of about 3,000 feet of overlying ice. Lodgement till typically has high-strength and Bethany Corner Subsurface Exploration Renton, Washington and Geotechnical Engineering Report December 16, 2016 ASSOCIATED EARTH SCIENCES, INC. MM/pc - EE160525A4 - Projects\20160525\EE\WP Page 3 low-compressibility attributes that are favorable for structural support with proper preparation. Lodgement till is typically silty, moisture-sensitive, and easily disturbed under wet site or weather conditions. Excavated lodgement till is suitable for reuse in structural fill applications under dry site and weather conditions when it can be moisture-conditioned to allow compaction to a firm and unyielding condition at the specified level for the intended purpose. Lodgement till is considered suitable for foundation support but is not considered a suitable infiltration receptor. The geologic units identified on the subject property closely match those units identified within the site area on the Geologic Map of Surficial Deposits in the Seattle 30’ by 60’ Quadrangle, Washington, by J.C. Yount and others, 1993. Hydrology Minor to abundant seepage was observed in all of our explorations. We anticipate that shallow ground water will be limited to interflow. Interflow commonly occurs in areas underlain by glacially consolidated sediments and originates as surface water that percolates down through the near-surface, relatively permeable surface soils, such as weathered lodgement till, and becomes trapped or “perched” atop the underlying, relatively impermeable, glacial sediments. Interflow is often a seasonal phenomenon. It should be noted that the presence and depth of seepage at the site may vary in response to such factors as changes in season, precipitation, and site use. Infiltration Feasibility The site is underlain at shallow depths by medium dense to very dense lodgement till and fill soils. Lodgement till generally consisted of silty fine sand with gravel and has been consolidated by the weight of an overriding ice sheet during the most recent ice age. As a result, the lodgement till has a low permeability due to its relative high density and high silt content and is not a suitable receptor for infiltration. In addition, the till layer commonly creates a perched ground water layer described in the previous section that will not allow adequate separation from high winter ground water for a proposed infiltration facility, if present. Therefore, we do not recommend the use of infiltration as a method for storm water disposal. DESIGN RECOMMENDATIONS Introduction Our explorations indicate that, from a geotechnical standpoint, the proposed project is feasible provided the recommendations contained herein are properly followed. The bearing stratum is generally shallow on the east end and conventional shallow foundations should perform well with proper subgrade preparation. The west end of the site will require that the unsuitable fill be removed to a depth of about 6 feet prior to the placement of additional structural fill or Bethany Corner Subsurface Exploration Renton, Washington and Geotechnical Engineering Report December 16, 2016 ASSOCIATED EARTH SCIENCES, INC. MM/pc - EE160525A4 - Projects\20160525\EE\WP Page 4 foundations. We recommend that building foundations are founded on the dense native, glacial till soils or structural fill placed on top of the native glacial till. Site Preparation Site preparation of the construction area should include removal of all previously placed fill, grass, brush, debris, and any other deleterious materials. Erosion and surface water control should be established around the clearing limits to satisfy local requirements. We recommend existing fill, be removed from below areas of shallow foundations. When structural fill is required for restoration of the planned foundation grade, our recommendations detailed in the “Structural Fill” section should be followed. Removal of unsuitable soil should extend laterally beyond the building footprint by a distance equal to the depth of overexcavation. For example, when existing fill is removed to a depth of 2 feet below a planned footing area, the excavation should also extend laterally 2 feet beyond the building footprint in that area. Where existing fill is removed and replaced with structural fill, conventional shallow foundations may be used for structure support. The required depth of removal should be determined in the field based on actual conditions encountered during excavation. Below planned on-site paving or under building slabs-on-grade, the stripped subgrade should be proof-rolled with heavy, rubber-tired construction equipment, such as a fully loaded tandem-axle dump truck. Proof-rolling should be performed prior to structural fill placement. The proof-roll should be monitored by the geotechnical engineer so that any soft or yielding subgrade soils can be identified. Any soft or loose, yielding soils should be removed to a stable subgrade. Proof-rolling should only be attempted if soil moisture contents are at or near optimum moisture content. Proof-rolling of wet subgrades could result in further degradation. 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) or flatter in the existing fill and underlying weathered glacial deposits, provided they are not saturated. Temporary slopes in unsaturated, unweathered lodgement till may be planned at 1H:1V. These slope angles are for areas where ground water seepage is not encountered, and assume that surface water is not allowed to flow across the temporary slope faces. If ground or surface water is present when the temporary excavation slopes are exposed, flatter slope angles will 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. Bethany Corner Subsurface Exploration Renton, Washington and Geotechnical Engineering Report December 16, 2016 ASSOCIATED EARTH SCIENCES, INC. MM/pc - EE160525A4 - Projects\20160525\EE\WP Page 5 Site Disturbance The on-site soils contain a high percentage of fine-grained material, which makes them easy to disturb during wet weather. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened during wet weather conditions. Structural Fill All references to structural fill in this letter-report refer to subgrade preparation, fill type and placement, and compaction of materials, as discussed in this section. If a percentage of compaction is specified under another section of this letter-report, the value given in that section should be used. After stripping, planned excavation, and any required overexcavation have been performed to the satisfaction of the geotechnical engineer, the upper 12 inches of exposed ground in areas to receive fill should be recompacted to a firm and unyielding condition. If the subgrade contains silty soils and 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 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 the modified Proctor maximum density using American Society for Testing and Materials (ASTM) D-1557 as the standard. Use of soils from the site in structural fill applications is acceptable if the material meets the project specifications for the intended use, and if specifically allowed by project specifications. In the case of roadway and utility trench filling, structural fill should be placed and compacted in accordance with current City of Renton codes and standards. The top of the compacted fill should extend horizontally outward a minimum distance of 3 feet beyond the locations of the roadway edges before sloping down at an angle of 2H:1V. Structural fills with sloping faces that cannot be compacted directly by a vibratory roller should be compacted by overbuilding, then cutting back to a compacted slope core. The contractor should note that any proposed fill soils must 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 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. Use of moisture-sensitive soil in structural fills should be limited to Bethany Corner Subsurface Exploration Renton, Washington and Geotechnical Engineering Report December 16, 2016 ASSOCIATED EARTH SCIENCES, INC. MM/pc - EE160525A4 - Projects\20160525\EE\WP Page 6 favorable dry weather conditions, and is only permitted if specifically allowed by project plans and specifications. The native soils present onsite contained significant amounts of silt and are considered highly moisture-sensitive. 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 with at least 25 percent retained on the No. 4 sieve. A representative from our firm should inspect the stripped subgrade and be present during placement of structural fill to observe the work and perform a representative number of in-place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses, and any problem areas may be corrected at that time. It is important to understand that taking random compaction tests on a part-time basis will not assure uniformity or acceptable performance of a fill. As such, we are available to aid the owner in developing a suitable monitoring and testing program. Ground Motion Structural design of the project should be in accordance with the 2015 International Building Code (IBC) using Site Class D. Foundations Spread footings that are supported on dense native lodgement till sediments or a combination of structural fill and dense native lodgement till sediments may be designed with an allowable foundation soil bearing pressure of 2,500 pounds per square foot (psf), including both dead and live loads. For the storm water vault located at the southeast corner of the site, a higher allowable bearing capacity of 3,000 psf can be used due to the increased depth of the excavation. An increase of one-third may be used for short-term wind or seismic loading for all foundations. Perimeter footings should be buried at least 18 inches into the surrounding soil for frost protection. However, all footings must penetrate to the prescribed bearing stratum, and no footing should be founded in or above organic or loose soils. It should be noted that the area bound by lines extending downward at 1H:1V from any footing must not intersect another footing or intersect a filled area that has not been compacted to at least 95 percent of ASTM D-1557. 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 described above should be on the order of ½ inch or less. However, disturbed soil not removed from footing excavations prior to footing placement Bethany Corner Subsurface Exploration Renton, Washington and Geotechnical Engineering Report December 16, 2016 ASSOCIATED EARTH SCIENCES, INC. MM/pc - EE160525A4 - Projects\20160525\EE\WP Page 7 could result in increased settlements. All footing areas should be inspected 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 letter-report. Such inspections may be required by the governing municipality. Perimeter footing drains should be provided, as discussed under the “Drainage Considerations” section of this letter-report. Lateral loads can be resisted by friction between the foundation and the natural glacial 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 = 350 pounds per cubic foot (pcf) • Coefficient of friction = 0.35 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 building. 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 building to achieve surface drainage. Lateral Wall Pressures 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 letter-report. Horizontally backfilled walls, which are drained and free to yield laterally at least 0.1 percent of their height, may be designed to resist active lateral earth pressure represented by an equivalent fluid equal to 35 pcf. Fully restrained, drained, horizontally backfilled, rigid walls that cannot yield such as the storm water vault should be designed for an at-rest equivalent fluid of 50 pcf. 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. Walls with sloping backfill are not expected; however, if walls with sloping backfill are planned, we should be contacted to offer situation-specific surcharge recommendations. 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 8H and 11H psf, where H is the wall height in feet, for the “active” and “at-rest” loading conditions, Bethany Corner Subsurface Exploration Renton, Washington and Geotechnical Engineering Report December 16, 2016 ASSOCIATED EARTH SCIENCES, INC. MM/pc - EE160525A4 - Projects\20160525\EE\WP Page 8 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 slab-on-grade floors 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 letter-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. Pavement Recommendations Pavement areas should be prepared in accordance with the “Site Preparation” section of this letter-report. If the stripped native soil subgrade can be compacted to 95 percent of ASTM D-1557 and is firm and unyielding, no additional preparation is required. Soft or yielding areas should be overexcavated to provide a suitable subgrade and backfilled with structural fill. The pavement sections included in this letter-report section are for driveway and parking areas onsite, and are not applicable to right-of-way improvements. If any new paving of public streets is required, we should be allowed to offer situation-specific recommendations. The exposed ground should be recompacted to a firm and unyielding condition. If required, structural fill may then be placed to achieve desired subbase grades. Upon completion of the recompaction and structural fill, a pavement section consisting of 3 inches of asphaltic concrete pavement (ACP) underlain by 4 inches of 1¼-inch crushed surfacing base course is the recommended minimum in areas of planned passenger car driving and parking. In driveway areas subjected to heavier loads, such as that from school buses or fire trucks, a minimum pavement section consisting of 4 inches of ACP underlain by 2 inches of 5/8-inch crushed surfacing top course and 4 inches of 1¼-inch crushed surfacing base course is recommended. The crushed rock course must be compacted to 95 percent of the maximum density, as determined by ASTM D-1557. All paving materials should meet gradation criteria contained in the current Washington State Department of Transportation (WSDOT) Standard Specifications. Bethany Corner Subsurface Exploration Renton, Washington and Geotechnical Engineering Report December 16, 2016 ASSOCIATED EARTH SCIENCES, INC. MM/pc - EE160525A4 - Projects\20160525\EE\WP Page 9 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 letter-report is based. If the reviewing agency requires the Engineer of Record to review the project during final design and construction, we are available. In this way, our earthwork and foundation recommendations may be properly interpreted and implemented in the design and construction of the project. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the building foundations 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 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. Everett, Washington Matthew A. Miller, P.E. Principal Engineer Attachments: Figure 1: Vicinity Map Figure 2: Site and Exploration Plan Appendix: Exploration Logs 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:EE160674A 12/16 1 Document Path: G:\GIS_Projects\aTemplatesNTRP\aVM_Template\VM_MXD\160674 Fig1 ProjectVicinity_Bethany.mxdDATA SOURCES / REFERENCES:USGS: 24K SERIES TOPOGRAPHIC MAPSKING CO: STREETS, CITY LIMITS, PARCELS 2016 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE KitsapCounty Snohomish County Pierce County King County SE 164th St 111thAveSE109thAveSE!( SITE¬«167 ¥405 ¬«515 BETHANY CORNERRENTON, WASHINGTON NOTES: 1. BASE MAP REFERENCE: D. L. STRONG CONSULTING ENGINEERS, BETHANY CORNER PRELIMINARY PLAY, PRELIMINARY PLAT PLAN, UNDATED.160674 Bethany Corner \ 160674 F2 Site-Explr.cdrBETHANY CORNER RENTON, WASHINGTON SITE AND EXPLORATION PLAN PROJ NO.DATE:FIGURE: KE160674A 12/16 2 BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION. a s s o c i a t e d e a r t h s c i e n c e s i n c o r p o r a t e d FEET 20 400 N CONTOUR INTERVAL = 2’ LEGEND: EXPLORATION PITEP NOTE: LOCATION AND DISTANCES SHOWN ARE APPROXIMATE. EP-3 EP-2 EP-1 EP-5 EP-4 APPENDIX Grass / Topsoil Vashon Lodgement Till Loose to medium dense, tannish gray, silty, fine SAND, some gravel; mottled (SM). Medium dense to dense, moist, tannish gray, silty, fine SAND, some gravel; unsorted (SM). Pre-Vashon Fine-Grained Stiff, moist to very moist, olive gray, fine sandy SILT, trace gravel (ML). As above. Bottom of exploration pit at depth 13.5 feet No seepage. No caving. DESCRIPTION Renton, WA Bethany Corner 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be readtogether with that report for complete interpretation. This summary applies only to the location of this trench at the time ofexcavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplficationof actual conditions encountered. Logged by: AWR Approved by: ????12/14/16 Project No. EE160674A LOG OF EXPLORATION PIT NO. EP-1 Depth (ft)KCTP3 160674.GPJ December 15, 2016 Grass / Topsoil Fill Loose, very moist, tan and dark gray, fine to medium SAND, some silt (SP-SM). Pockets of organic soil and debris. Operator notes harder digging. Vashon Lodgement Till Medium dense, wet, gray, silty, fine SAND; mottled (SM). As above. Bottom of exploration pit at depth 8 feetModerate seepage at 3 feet. Heavy caving from 2 to 6 feet. DESCRIPTION Renton, WA Bethany Corner 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be readtogether with that report for complete interpretation. This summary applies only to the location of this trench at the time ofexcavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplficationof actual conditions encountered. Logged by: AWR Approved by: ????12/14/16 Project No. EE160674A LOG OF EXPLORATION PIT NO. EP-2 Depth (ft)KCTP3 160674.GPJ December 15, 2016 Grass / Topsoil Fill Loose, moist, tannish brown, silty, fine SAND, some gravel; contains pockets of organics (SM). Operator notes harder digging. Vashon Lodgement Till Medium dense, wet, grayish tan, silty, fine SAND; mottled (SM). Dense, moist, tan, silty, fine SAND, some gravel; mottled (SM). Bottom of exploration pit at depth 8.5 feet Moderate seepage from 3 to 5 feet. Moderate caving from 2 to 5 feet. DESCRIPTION Renton, WA Bethany Corner 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be readtogether with that report for complete interpretation. This summary applies only to the location of this trench at the time ofexcavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplficationof actual conditions encountered. Logged by: AWR Approved by: ????12/14/16 Project No. EE160674A LOG OF EXPLORATION PIT NO. EP-3 Depth (ft)KCTP3 160674.GPJ December 15, 2016 Grass / Topsoil Fill Loose to medium dense, very moist, tannish brown, silty, fine SAND, some gravel; contains organics soil and debris (SM). Pre-Vashon Fine-Grained Medium stiff, very moist to wet, olive gray, fine sandy SILT (ML). Tukwila Formation Weathered SAND / SILT STONE. Bottom of exploration pit at depth 10 feetMinor seepage from 2 to 3 feet. Minor caving from 1 to 5 feet. DESCRIPTION Renton, WA Bethany Corner 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be readtogether with that report for complete interpretation. This summary applies only to the location of this trench at the time ofexcavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplficationof actual conditions encountered. Logged by: AWR Approved by: ????12/14/16 Project No. EE160674A LOG OF EXPLORATION PIT NO. EP-4 Depth (ft)KCTP3 160674.GPJ December 15, 2016 Grass / Topsoil Fill Loose, very moist, tannish brown, silty, fine SAND, some gravel, trace organic debris (SM). Vashon Lodgement Till Medium dense, wet, tan, silty, fine SAND, some gravel (SM). Dense, moist, tannish gray, silty, fine SAND, some gravel; unsorted (SM). Bottom of exploration pit at depth 7.5 feetModerate seepage at 4 feet. Minor caving from 2 to 5 feet. DESCRIPTION Renton, WA Bethany Corner 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) for the named project and should be readtogether with that report for complete interpretation. This summary applies only to the location of this trench at the time ofexcavation. Subsurface conditions may change at this location with the passage of time. The data presented are a simplficationof actual conditions encountered. Logged by: AWR Approved by: ????12/14/16 Project No. EE160674A LOG OF EXPLORATION PIT NO. EP-5 Depth (ft)KCTP3 160674.GPJ December 15, 2016