HomeMy WebLinkAboutSanitary Sewer Geotech Report Finale a r t h w a t e r + GEOTECHNICAL ENGINEERING REPORT City of Renton Sanitary Sewer Replacement Project Prepared for: Carollo Engineers, Inc. Project No. AS210428-100  July 19, 2024 FINAL ear t h +w ate r Aspect Consulting 710 2nd Avenue Suite 550 Seattle, WA 98104 206.328.7443 www.aspectconsulting.com GEOTECHNICAL ENGINEERING REPORT City of Renton Sanitary Sewer Replacement Project Prepared for: Carollo Engineers, Inc. Project No. AS210428-100  July 19, 2024 FINAL Aspect Consulting Erik O. Andersen, PE Senior Principal Geotechnical Engineer erik.andersen@aspectconsulting.com Julia Martz, EIT Geotechnical Engineer Julia.martz@aspectconsulting.com V:\210428 2022 Sanitary Sewer Rplcmnt Prjct\Deliverables\Geotechnical Report\Final\City of Renton Sanitary Sewer Geotech Report_Final_2024.07.19.docx 7/19/2024 ASPECT CONSULTING PROJECT NO. AS210428-100  JULY 19, 2024 FINAL i i Contents 1 Introduction ................................................................................................. 1 1.1 Project Description and Background ........................................................... 1 2 Site Conditions ............................................................................................ 2 2.1 Site Descriptions and Surface Conditions ................................................... 2 2.1.1 Site 1 – Kirkland Ave NE and NE 16th St ............................................... 2 2.1.2 Site 2 – NE 4th St .................................................................................. 2 2.1.3 Site 3 – NE 6th PL and NE 7th PL .......................................................... 2 2.1.4 Site 4 – Tacoma Ave NE, NE 6th St, and Shelton Ave NE ..................... 3 2.1.5 Site 5 – NE 6th St .................................................................................. 3 2.1.6 Site 6 – Taylor Ave NW and NW 7th St .................................................. 3 2.1.7 Site 7 – Monroe Ave NE ....................................................................... 3 2.2 Geologic Setting ......................................................................................... 4 2.3 Subsurface Conditions ............................................................................... 4 2.3.1 Explorations by Aspect ......................................................................... 5 2.3.2 Stratigraphy .......................................................................................... 5 2.3.3 Groundwater ......................................................................................... 6 3 Geotechnical Engineering Conclusions and Recommendations ........... 8 3.1 Temporary Excavations and Shoring .......................................................... 8 3.2 Construction Dewatering ............................................................................ 9 3.3 Backfill and Compaction ........................................................................... 10 3.3.1 Utility Bedding and Backfilling ............................................................. 10 3.3.2 Structural Fill ....................................................................................... 10 3.4 Feasibility of Replacing Service Laterals via Trenchless Methods ............ 11 3.4.1 Pipe Bursting ...................................................................................... 11 3.4.2 Ground Response............................................................................... 12 4 Recommendations for Continuing Geotechnical Services .................... 13 4.1 Additional Design and Consulting Services .............................................. 13 4.2 Additional Construction Services .............................................................. 13 5 References ................................................................................................. 14 6 Limitations ................................................................................................. 15 ASPECT CONSULTING ii FINAL PROJECT NO. AS210428-100  JULY 19, 2024 List of Figures 1 Site Overview Map 2 Exploration Plan 3 Geology Map 4 Temporary Lateral Shoring Pressures List of Appendices A Subsurface Exploration Logs B Geotechnical Laboratory Analysis Results C Previous Explorations by Others D Report Limitations and Guidelines for Use ASPECT CONSULTING PROJECT NO. AS210428-100  JULY 19, 2024 FINAL 1 1 1 Introduction This report presents the results of Aspect Consulting’s, a Geosyntec company (Aspect), geotechnical investigation and evaluation supporting the City of Renton’s (City) 2022 Sanitary Sewer Replacement Project (Project) in Renton, Washington. The Project includes replacement of gravity sewer mains, sewer manholes, and service laterals located at seven sites within City right-of-way (ROW) and on private property within City easements (Site; Figure 1). The Project design and permitting is being led by Carollo Engineers, Inc. (Carollo) on behalf of the City. This report summarizes the results of completed desktop review, field investigations, and laboratory testing and presents Aspect’s geotechnical design and construction recommendations for the Project. 1.1 Project Description and Background Our understanding of the proposed improvements is based on communications with Carollo and our review of preliminary design concepts provided by Carollo. We understand the overall Project goal is to support annual sanitary sewer rehabilitation and replacements as part of the City Wastewater Utility’s ongoing capital improvement program. The Project includes replacement of approximately 1,600 linear feet (LF) of 8- inch sewer main, approximately 120 LF of 12-inch sewer main, replacing or abandoning 13 sewer manholes, and replacing 32 service laterals. Based on our review of available record drawings and utility data, we understand the sewer mains and manhole structures are generally less than 20 to 25 feet below ground surface (bgs). Aspect’s scope of work included a data review and Site reconnaissance, subsurface explorations, and laboratory testing for four sites (Sites 3, 4, 5, and 7), and desktop review only for the three remaining sites (Sites 1, 2, and 6) with the use of available public data, geologic maps, and nearby previous explorations by Aspect and others. Our work was completed in accordance with our agreement with Carollo, executed June 10, 2022. Key geotechnical considerations that are addressed in this report include design and construction recommendations for temporary excavations and shoring, construction dewatering, trenching and backfilling, and the feasibility of replacing service laterals via trenchless methods. ASPECT CONSULTING 2 FINAL PROJECT NO. AS210428-100  JULY 19, 2024 2 Site Conditions The sections below describe conditions for Sites 1 through 7 gathered and inferred from our review of publicly available information (i.e., maps, photographs, etc.), our observations made during a Site reconnaissance visit on July 20, 2022, and the results of our subsurface exploration program completed between July 25 and 27, 2022. 2.1 Site Descriptions and Surface Conditions All locations are within the City, with most sites in the Renton Highlands area (Figure 1). The Sites range in distance from each other from 550 feet to 2 miles apart. The Site conditions are described separately below. 2.1.1 Site 1 – Kirkland Ave NE and NE 16th St Site 1 is located on Kirkland Avenue Northeast, just south of the Northeast 16th Street intersection, and consists of a north-south oriented two-lane paved roadway with street- parking and sidewalks on both the east and west sides. The lanes of travel span approximately 20 feet. Topography is flat within the Site at an elevation (EL) 379.1 Site 1 is bounded by the Kirkland Avenue Townhomes to the east and private residential properties to the west. Proposed improvements at Site 1 include replacement of a manhole and associated pipe repairs. This Site was reviewed using only publicly available information. Aspect did not conduct in-person reconnaissance or subsurface explorations at this Site and all input provided on this Site is an interpretation of readily available information. 2.1.2 Site 2 – NE 4th St Site 2 is located on Northeast 4th Street, an east-west oriented four-lane paved roadway with a center lane and sidewalks on both the north and south sides. The roadway is approximately 50 feet in width with two lanes of travel for eastbound and westbound traffic. The topography is flat at an elevation of EL 345. The Site is bounded by the Cedar Park Apartments and the Renton Highland Self-Storage to the north, and by the Greenwood Memorial Park to the south. Proposed improvements at Site 2 include replacement of a manhole and associated pipe repairs. This Site was reviewed using only publicly available information. Aspect did not conduct in-person reconnaissance or subsurface explorations at this Site and all input provided on this Site is an interpretation of readily available information. 2.1.3 Site 3 – NE 6th PL and NE 7th PL Site 3 is located on a northwest-to-southeast oriented section of Northeast 7th Place, which encompasses a cul-de-sac on NE 7th PL and runs to the intersection of NE 7th PL and NE 6th PL.. The roadway is a paved two-lane residential street approximately 28 feet wide with no sidewalk. Topography at the site is gently sloped to the southeast at a 2 percent gradient from EL 375 in the NE 7th PL cul-de-sac to EL 369 within the intersection. The Site is bounded by private residential properties to all sides. 1 Elevation is estimated and in feet above mean sea level (MSL). ASPECT CONSULTING PROJECT NO. AS210428-100  JULY 19, 2024 FINAL 3 3 Proposed improvements at Site 3 include replacement of a gravity main pipe. Aspect conducted reconnaissance and one subsurface exploration at this Site (see Figure 2). 2.1.4 Site 4 – Tacoma Ave NE, NE 6th St, and Shelton Ave NE Site 4 contains multiple locations along Shelton Avenue Northeast, Tacoma Avenue Northeast, and Northeast 6th Street. Shelton Ave NE and Tacoma Ave NE are roughly north-south-oriented paved residential streets while NE 6th St is an east-west-oriented paved residential street. All streets are two lanes and approximately 28 feet wide with no sidewalk. Topography at the site broadly slopes to the southeast and elevations range from EL 419 to EL 403. The Site is bounded by private residential properties on all sides. Proposed improvements at Site 4 include replacement of existing gravity main pipe, several laterals, and several manholes. Aspect conducted reconnaissance and two subsurface explorations at this Site (see Figure 2). 2.1.5 Site 5 – NE 6th St Site 5 is located on Northeast 6th Street between Monroe Avenue Northeast and Olympia Avenue Northeast. The Site runs along an east-to-west oriented paved two-land roadway that is approximately 34 feet wide with no sidewalk. Topography at the Site is roughly sloped beginning at EL 380 near Monroe Ave NE, rising to EL 387 in the center, and falling to EL 363 in the east. The Site is bounded by private residential properties on all sides. Proposed improvements at Site 5 include replacement of existing gravity main pipe, several laterals, and several manholes. Aspect conducted reconnaissance and one subsurface exploration at this Site (see Figure 2). 2.1.6 Site 6 – Taylor Ave NW and NW 7th St Site 6 is located within the intersection of Northwest 7th Street and Taylor Avenue Northwest. The intersection is a paved area where two two-lane residential roads meet with no sidewalk. Topography at the Site is level at EL 125 ft within the proposed rehabilitation area. The intersection is at the top of an east-facing 3.5H:1V (Horizontal: Vertical) slope that rises 70 feet above Rainier Avenue North and the Renton municipal Airport. The Site is bounded by private residential properties on all sides. Proposed rehabilitation at Site 6 includes replacement of a manhole and associated pipe repairs. This Site was reviewed using only publicly available information. Aspect did not conduct in-person reconnaissance or subsurface explorations at this Site and all input provided on this Site is an interpretation of readily available information. 2.1.7 Site 7 – Monroe Ave NE Site 7 is located near Monroe Avenue Northeast from approximately 300 feet north of Northeast 10th Street to Northeast 7th Street, in a utility easement behind private residences between Monroe Ave NE and Lynnwood Ave NE. Topography at the site roughly slopes down towards the south from approximately EL 395 to EL 376. Proposed rehabilitation at Site 7 includes replacement of existing gravity main pipe. Aspect conducted reconnaissance and two subsurface explorations at this Site (see Figure 2). ASPECT CONSULTING 4 FINAL PROJECT NO. AS210428-100  JULY 19, 2024 2.2 Geologic Setting The Sites are located within the Puget Lowland, a broad area of tectonic subsidence flanked by two mountain ranges: the Cascades to the east and the Olympics to the west. The sediments within the Puget Lowland are the result of repeated cycles of glacial and nonglacial deposition and erosion. The most recent cycle, the Vashon Stade of the Fraser Glaciation (about 13,000 to 16,000 years ago), is responsible for most of the present day geologic and topographic conditions. During the Vashon Stade, the 3,000-foot-thick Cordilleran Glacier advanced into the Puget Lowland. As the Cordilleran Glacier advanced southward, lacustrine and fluvial sediments were deposited in front of the glacier. Preglacial and proglacial sediments were overridden and consolidated by the advancing glacier, creating dense and hard soil deposits. At the interface between the advance soils and the glacial ice, the Cordilleran Glacier sculpted and smoothed the surface, and then deposited a consolidated basal till. As the Cordilleran Glacier retreated northward from the Puget Lowland to British Columbia, it left an unconsolidated (relatively loose) sediment veneer over the denser, glacially consolidated deposits. The most recent geologic maps of the Sites (Yount et al., 1993 and Mullineaux, 1965) show the Sites as directly underlain by Vashon-age ablation till and lodgment till deposits (Qgt; Sites 1,3,4,5,7), recessional outwash (Qpa; Site 2), or recessional kame terrace deposits (Qit; Site 6), as represented on Figure 3. Nearby mapped geologic units include undifferentiated deposits (Qu), which may include glacial and non-glacial deposits of pre- Vashon-age. During our subsurface exploration program, we also encountered older glaciofluvial deposits beneath the mapped geologic units at Sites 3, 5, and 7. Unit descriptions from the geologic maps are paraphrased and summarized below: • (Vashon-age) Recessional outwash (Qpa): glaciofluvial deposits; chiefly well- sorted to interbedded sand and gravel deposited along the Cedar River valley. • (Vashon-age) Recessional kame terrace deposits (Qit): sand and gravel in scattered terraces whose surfaces locally are deformed by extensive collaps e. • (Vashon-age) ground moraine deposits (Qgt): map unit includes ablation till over lodgement till. Both are unsorted mixtures of sand, silt, and gravel. Lodgement till is dense and hard; ablation till is loose to medium dense. • Undifferentiated deposits (Qu): deposits of unknown age and origin that may include both Vashon-age and pre-Vashon deposits. Includes three or more till sheets, glaciofluvial sand and gravel, glaciolacustrine clay and sand, and non- glacial sand, clay, and thin peat. Exposed mostly in cut slopes and drainage valleys. 2.3 Subsurface Conditions Aspect inferred subsurface conditions at the Sites from the desktop review at Sites 1, 2, and 6, the completed field investigations at Sites 3, 4, 5, and 7, a review of applicable geologic literature, our local geologic experience, and geotechnical laboratory testing. A more detailed description of the field exploration methods and summary exploration logs are presented in Appendix A. The results of our geotechnical laboratory analyses are ASPECT CONSULTING PROJECT NO. AS210428-100  JULY 19, 2024 FINAL 5 5 included in Appendix B. Nearby explorations by both Aspect and others that were utilized in the desktop review can be found in Appendix C and are shown on Figure 3. 2.3.1 Explorations by Aspect Aspect completed six drilled soil borings (designated AB-01 through AB-06) between Sites 3, 4, 5, and 7 between July 25 and 27, 2022. The exploration locations are shown on Figure 2. We completed each boring to depths of approximately 30 to 37 feet bgs using hollow-stem auger drilling techniques with in-situ density/consistency testing and sample collection at selected depth intervals. 2.3.2 Stratigraphy The results of our desktop review of available subsurface information, previous explorations, and our subsurface investigations indicate the Sites are underlain by fill and Vashon-age glacial deposits. The Vashon-age glacial deposits varied across Sites and descriptions of the deposits, as well as at which Sites they were encountered, are detailed in the following sections. Fill We encountered fill at Sites 1 (AB-02) and 4 (AB-05 and AB-06) consisting of medium to very dense, slightly moist to moist, gray to brown sand with varying amounts of silt and gravel (SM, SP, SP-SM ). Fill was encountered at these explorations from the ground surface to depths of between approximately 3 to 8 feet bgs. We interpret the fill as being associated with development of nearby roadways, utilities, and embankments. At Sites 1, 2, and 6 we performed only a desktop review of available subsurface information. Based on this information and our nearby subsurface investigations, it is possible that subsurface conditions at Sites 1, 2, and 6 could include comparable fill material. The fill generally exhibits low to moderate shear strength, moderate compressibility, and moderate to high permeability. Vashon recessional kame terrace deposits (Qit) In our opinion, Vashon recessional kame terrace deposits could be encountered at Site 6, which Aspect evaluated only via a desktop review of readily available information. No subsurface explorations logs were available near Site 6 in Ecology’s database of subsurface explorations by others where Vashon recessional kame terrace deposits were encountered to describe the deposit in greater detail than the geologic map. However, Vashon recessional kame terrace deposits are mapped at Site 6. The geologic map indicates kame terrace deposits consist generally of sand, fine to coarse gravel, and cobbles. Based on the depositional environment described in the geologic map, we expect recessional kame terrace deposits to exhibit low to moderate shear strength, moderate compressibility, and moderate to high permeability. Vashon recessional outwash deposits (Qpa) We encountered recessional outwash at Site 3 in AB-03, consisting of medium dense to very dense, moist, brown to gray silty sand and sand with varying amounts of gravel (SM, SP-SM). ASPECT CONSULTING 6 FINAL PROJECT NO. AS210428-100  JULY 19, 2024 Based on our desktop review, we also expect Vashon recessional outwash deposits may be present underlying fill at Site 2. Aspect previously conducted explorations not associated with this Project approximately 1,000 feet to the southwest of Site 2 (Aspect, 2020). Explorations at these sites encountered Vashon recessional outwash deposits (Qpa) consisting of medium dense to dense, moist, brown sand with varying amounts of silt and gravel (SP, SP-SM, SW-SM, SM), and gravel with varying amounts of silt, sand, and cobbles (GW, GP, GP-GM, GM). The recessional outwash encountered exhibits low to moderate shear strength, moderate compressibility, and moderate to high permeability. Vashon ground moraine deposits – lodgement till (Qgt) We encountered lodgement till at Sites 4, 5, and 7 in AB-01, AB-04, AB-05, and AB-06 consisting of dense to very dense, moist, gray silty sand with varying amounts of gravel (SM). Based on our desktop review, we also expect lodgement till to be present at depth underlying Sites 1, 2, and 6. Lodgement till exhibits high shear strength, low compressibility, and low permeability. Glaciofluvial facies of undifferentiated deposits (Qu) We encountered glaciofluvial facies of undifferentiated deposits (Qu) at Sites 3, 5, and 7 in AB-01, AB-02, AB-03, and AB-04 consisting of dense to very dense, moist, brown to gray brown silty sand and sand with varying amounts of gravel (SM, SP-SM). Although not encountered in the explorations, the glaciofluvial facies of undifferentiated deposits (Qu) could contain cobbles and/or boulders. In contrast to the surficial recessional deposits described above, the glaciofluvial facies of undifferentiated deposits (Qu) have been consolidated under glacial advance. Glaciofluvial facies of undifferentiated deposits (Qu) exhibit high shear strength, low compressibility, and moderate permeability. Undifferentiated deposits (Qu) Based on our desktop review, we expect that undifferentiated deposits (Qu) may be present at Site 6 underlying the Vashon till, based on mapped unit contacts on the hillslope immediately east of the Site and nearby explorations by others. Descriptions of this deposit (Earth Consultants, 1991) describe the unit as interbedded silts (ML), sands (SM and SP-SM), and clay (CL). 2.3.3 Groundwater Groundwater was not encountered in any of our explorations, except for AB-05. We interpret the groundwater we encountered at AB-05 at approximately 17 feet bgs as seepage from a localized zone of perched groundwater within the lodgement till deposits. A groundwater monitoring well with pressure transducer datalogger was installed at AB-05 to monitor the water level here. The groundwater level was recorded from July 2022 through June 2024, and it fluctuated from seasonal highs of approximate Elevation 402 (15 feet bgs) in the late winter to early spring months, to seasonal lows of approximate Elevation 398 (19 feet bgs) in the late summer through early fall months. ASPECT CONSULTING PROJECT NO. AS210428-100  JULY 19, 2024 FINAL 7 7 The regional groundwater table is below the depth of the improvements associated with the Project. However, localized seepage and perched groundwater zones may exist depending on local subsurface conditions, precipitation, and the time of year. ASPECT CONSULTING 8 FINAL PROJECT NO. AS210428-100  JULY 19, 2024 3 Geotechnical Engineering Conclusions and Recommendations Based on our evaluation, it is our opinion that the Project is feasible from a geotechnical perspective, provided the recommendations in this report are properly incorporated into design and construction. Key geotechnical considerations are summarized below and discussed in detail in subsequent sections: • In our explorations at Sites 3, 4, 5, and 7 we generally encountered medium dense surficial fill from recent roadway development activities or Vashon recessional outwash deposits (Qpa), underlain by dense to very dense glaciofluvial facies of undifferentiated deposits (Qu) or lodgement till (Qgt). We expect the regional groundwater table to be below the depth of the planned improvements, although localized seepage and perched groundwater zones may exist. • Open cut excavations will likely be the Contractor’s preferred installation method for piping and drainage structures. We have included construction recommendations for temporary excavations and recommended temporary lateral earth pressures to support implementation of Contractor-designed shoring systems. • The Contractor should be prepared to encounter localized zones of perched groundwater at any Site, which would require implementation of a Contractor- designed dewatering system. In our opinion, it will be feasible to manage groundwater seepage within open trench excavations using sumps and pumps. • We believe it is generally feasible to replace small-diameter service laterals at the Sites with the use of conventional trenchless pipe bursting methods. 3.1 Temporary Excavations and Shoring At the time of this draft report, details regarding sewer replacement (including trench depths and pipe sizes) had not been provided to Aspect. This information should be provided for our review as the Project design advances. We anticipate open trench excavations can be completed using conventional equipment. The Contractor should be aware that dense soils, such as lodgement till or undifferentiated deposits, may require more robust excavation equipment capable of excavating through very dense, glacially consolidated material (i.e., larger excavators with toothed buckets). The trench excavations may be cut vertically up to 4 feet deep and should be sloped above that depth a maximum of 1.5H:1V to a maximum excavation depth of 20 feet, in accordance with OSHA requirements for Type C soils. Deeper trench excavations may require shoring systems depending on the space available for sloped excavations and efficiency desired. The Contractor should be aware that relatively looser soils that have not been densified by glacial advance, such as fill or recessional outwash, may ravel when laid back and may require temporary excavations at less steep inclinations than would otherwise be permitted by OSHA. Open cut trench excavations are anticipated to be the preferred installation method. The means and methods of supporting temporary excavations will be the Contractor’s ASPECT CONSULTING PROJECT NO. AS210428-100  JULY 19, 2024 FINAL 9 9 responsibility. Trench support to protect workers typically consists of passive trench support systems (i.e., trench boxes or speed shoring) that allow the sides of the trenches to slough and still protect the workers. Temporary excavations that are properly dewatered and protected by engineered trench boxes may be cut as steeply as the soil will stand, in some cases near vertical. For planning purposes, shoring for the Project may be designed utilizing the temporary lateral earth pressures on Figure 4. When areas of deeper excavation and trenching are identified during final design, Aspect should review those locations and provide additional input on the temporary shoring design, as needed. General recommendations for design and implementation of trench shoring systems are presented below: • Shoring should be designed and constructed to support lateral soil loads, and any surcharge loads from construction equipment, construction materials, excavated soils, and vehicular traffic (see Figure 4 for lateral soil loads). • Precautions should be taken during removal of the shoring or sheeting materials to minimize disturbance of the pipe, underlying bedding materials, adjacent structures/utilities and surrounding soils. • The Contractor should be responsible for repair of any deformation or damages that occur to adjoining facilities along/adjacent to the trench alignment. Maintenance of safe working conditions, including temporary excavation stability, is the responsibility of the Contractor. All temporary cuts more than 4 feet in height that are not protected by trench boxes or otherwise shored, should be sloped in accordance with Part N of Washington Administrative Code (WAC) 296-155 for worker safety (WSL, 2022). Using guidance provided by the WAC and our Site observations, we classify the Site soils as Type C with a maximum allowable temporary slope inclination of 1.5H:1 V, although this may be difficult to maintain in looser, sandy Site soils such as fill without raveling of the excavation face. With time and the presence of seepage and/or precipitation, the stability of temporary unsupported cut slopes can be significantly reduced. Therefore, all temporary slopes should be protected from erosion by installing a surface water diversion ditch or berm at the top of the slope if precipitation is expected. In addition, the Contractor should monitor the stability of the temporary cut slopes and adjust the construction schedule and slope inclination accordingly. Vibrations created by traffic and construction equipment may cause caving and raveling of the temporary slopes. In such an event, lateral support for the temporary slopes should be provided by the Contractor. 3.2 Construction Dewatering Groundwater seepage and/or flow into excavations is largely dependent on the presence of perched groundwater that could potentially be encountered during construction. In our opinion, it is feasible to manage this seepage by controlling the size of the excavations and with sumps and submersible/trash pumps. The Contractor should be required to adequately dewater excavations, so that subgrade preparation and structural fill placement can be completed in dry conditions. We ASPECT CONSULTING 10 FINAL PROJECT NO. AS210428-100  JULY 19, 2024 anticipate that strategically placed sumps and pumps will sufficiently control water from inside the excavations. Sumps are often constructed by placing a short section of perforated corrugated steel pipe (or surplus 8- to 12-inch-diameter well screen) in a small hole excavated below the trench bottom elevation. The annular space around the pipe is backfilled with drain rock, with several inches placed inside the casing to help control the pumping of fines. Submersible pumps (or trash pump inlets) are then placed inside the casing and connected to a central discharge pipe. The Contractor should be responsible for design, implementation, and any necessary permits associated with any construction dewatering system used for the Project. 3.3 Backfill and Compaction Project construction will involve temporary excavations and backfill for the open cut trench utility installations. In our opinion, fines content of the Site soils are too high for reuse as structural fill to backfill temporary excavations. We recommend that imported structural fill meeting the applicable Washington State Department of Transportation (WSDOT) requirements be used for utility bedding and backfill. 3.3.1 Utility Bedding and Backfilling General recommendations for bedding of utilities and backfill of utility trenches include: • Materials to be used for utility bedding and backfill should meet the requirements for WSDOT Standard Specification 9-03.12(3) for Gravel Backfill for Pipe Zone Bedding (WSDOT, 2022). • Bedding and backfill material placed around pipes should be manually tamped into place on each side of the pipe to obtain complete contact. Pipe bedding material should be used as trench backfill to at least 6 inches above the top of the pipe, for the full width of the trench. • Trench backfill over 6 inches above the top of the pipe should meet the requirements for structural fill as described below. • Utility bedding and backfill should be mechanically compacted in lifts no greater than 6 inches from base to springline and from springline to the top of pipe using a jumping jack. Hoe-packs, sheepsfoots, and vibratory rollers shall not be used within 12 inches above the pipe. 3.3.2 Structural Fill Structural fill should consist of clean, nonplastic, relatively free -draining, sand and gravel free from organic matter or other deleterious materials. Such materials should typically contain particles of less than 4 inches maximum dimension, with less tha n 7 percent fines (material passing the U.S. Standard No. 200 sieve; based on the 3/4-inch fraction), as described in Section 9-03.14(1) of the WSDOT Standard Specifications (WSDOT, 2022) for Gravel Borrow. Based on the results of our subsurface explorations, the fines content of the on-Site material is too high to meet these requirements, thus structural fill will need to be imported from a suitable source. Structural fill should be placed in loose, horizontal lifts of not more than 9 inches in thickness and compacted to at least 95 percent of the maximum dry density, as determined using test ASPECT CONSULTING PROJECT NO. AS210428-100  JULY 19, 2024 FINAL 11 11 method ASTM D1557 (Modified Proctor). At the time of placement, the moisture content of structural fill should be at or near optimum. The procedure required to achieve the specified minimum relative compaction depends on the size and type of compaction equipment, the number of passes, thickness of the layer being compacted, and the soil moisture -density properties. When the first lift of fill is placed in a given area, and/or anytime the fill material changes, the area should be considered a test section. The test section should be used to establish fill placement and compaction procedures required to achieve proper compaction. Aspect or qualified materials inspection personnel should observe placement and compaction of the test section to assist in establishing an appropriate compaction procedure. Once a placement and compaction procedure is established, the Contractor’s operations should be monitored and periodic density tests performed to verify that proper compaction is being achieved. 3.4 Feasibility of Replacing Service Laterals via Trenchless Methods It is our understanding that trenchless construction methods are being considered for the replacement of small-diameter (i.e., approximately 4- to 6-inch) sewer service laterals. In our opinion, it is feasible to use conventional pipe bursting methods if the recommendations in the following sections are followed. 3.4.1 Pipe Bursting Pipe bursting is a method of trenchless pipe replacement that uses fracture and expansion to replace an existing sewer line. This is typically accomplished by pulling an expander head (also known as a “bursting head”) through an existing pipe, fracturing it, and forcing the fragments outwards into surrounding soil. Simultaneously, a new pipe of equal or greater diameter connected to the back end of the expander head, is placed. This process takes place from launching and receiving pits. Favorable ground conditions for pipe bursting are within soils that can be moderately compacted such that the enlarged hole behind the bursting head does not cave in before the replacement pipe is installed. This scenario results in minimal lateral extent of outward ground movement because the volume change is accommodated by the local soils. In addition, the absence of caving behind the bursting head will result in lower drag and reduced tensile stress on the pipe during installation. The magnitude of the drag force on the pipe during installation is highly dependent on the Contractor’s equipment and procedures. Less favorable ground conditions include densely compacted soils, and soils below the water table. These ground conditions tend to increase the force required for the bursting operation. Based on the soils encountered in our field exploration program, and assuming that existing service laterals are most likely within previous trenched excavations backfilled with medium dense compacted fill, we believe that pipe bursting is a feasible trenchless construction method for the service lateral replacements at the Sites. The Contractor should anticipate variable soil conditions that will affect the amount of force required to burst and pull replacement pipe. ASPECT CONSULTING 12 FINAL PROJECT NO. AS210428-100  JULY 19, 2024 3.4.2 Ground Response Location and proximity of nearby utilities, other service lines, or underground structures should be considered and evaluated before using pipe bursting trenchless methods. The Contractor shall be responsible for utilizing appropriate tools and equipment to evaluate the potential effects of ground displacement and vibrations due to pipe bursting operations. Some ground displacement should typically be expected as a result of pipe bursting procedures. Displacements tend to be localized and develop in the direction of least resistance, which is typically upwards. The magnitude and orientation of the displaced soil is largely dependent upon the degree of pipe upsizing, the type and compaction level of the soil surrounding the pipe, and the depth of the pipe. Typically, loose soils will undergo uniform displacement where more densely compacted soils at the same depth will most likely exhibit vertical (heave) expansion. The localized restraining effect of strong soils along trench sides and bottom also serves to direct ground movement upward above the pipe. Conversely, if the existing pipes are founded on weak soil, displacement would be directed downward. We expect that most of the service laterals being replaced are generally shallow. Generally, ground movement (heaving) that may distort the existing ground surface is observed during pipe bursting conducted on shallow pipes. Therefore, we recommend a specialty Contractor who is experienced in shallow, small -diameter lateral replacements be engaged to complete this work. The Contractor should be responsible for selecting equipment, methods, and workmanship that minimizes the potential for displacements at the ground surface. As a contingency, we recommend the contract include an allowance to complete minor repairs of the ground surface and final resurfacing and restoration if trenchless methods impact the surface. ASPECT CONSULTING PROJECT NO. AS210428-100  JULY 19, 2024 FINAL 13 13 4 Recommendations for Continuing Geotechnical Services Throughout this report, we have provided recommendations where we consider it would be appropriate for Aspect to provide additional geotechnical input to the design and construction process. Additional recommendations are summarized in this section. 4.1 Additional Design and Consulting Services Before construction begins, we recommend that Aspect: • Continue to meet with the design team, as needed, to address geotechnical questions that may arise throughout the remainder of the design process. • Review the geotechnical elements of the design plans to see that the geotechnical engineering recommendations are properly interpreted. 4.2 Additional Construction Services We are available to provide geotechnical engineering and monitoring services during construction. The integrity of the geotechnical elements depends on proper Site preparation and construction procedures. In addition, engineering decisions may have to be made in the field if variations in subsurface conditions become apparent. During the construction phase of the Project, we recommend that Aspect be retained to perform the following tasks: • Review applicable submittals. • Observe and evaluate installation of temporary shoring and excavations. • Observe and evaluate subgrade preparation and utility bedding/structural fill placement. • Attend meetings virtually or on-Site, as needed. • Advise on other geotechnical engineering considerations that may arise during construction. The purpose of our observations is to verify compliance with design concepts and recommendations, and to allow design changes or evaluation of appropriate construction methods if subsurface conditions differ from those anticipated prior to the start of construction. ASPECT CONSULTING 14 FINAL PROJECT NO. AS210428-100  JULY 19, 2024 5 References Aspect Consulting LLC (Aspect), 2020, Geotechnical Evaluation for Potential Stormwater Facilities, Technical Memorandum, Monroe Avenue NE Storm System Improvements, Renton, Washington, Aspect Project No. 190398, dated December 23, 2020. City of Renton (City), 2022, City of Renton Map Viewer, https://maps.rentonwa.gov/Html5viewer/Index.html?viewer=cormaps, accessed July 18, 2022, Earth Consultants, Inc. (Earth Consultants), 1991, Geotechnical Engineering Study Slope Failure Causation Report, Pentzold Residence, 11900 87th Avenue South, King County, Washington, dated September 5, 1991. Mullineaux, D.R., 1965, Geologic map of the Renton quadrangle, King County, Washington, U.S. Geological Survey, Geologic Quadrangle Map GQ-405, 1:24,000. Washington State Department of Transportation (WSDOT), 2022, Standard Specifications for Road, Bridge, and Municipal Construction, M 41-10, August 22, 2021. Washington State Legislature (WSL), 2022, Washington Administrative Code, Chapter 296-155: Safety Standards for Construction Work, Updated July 19, 2022. Yount, J.C., Minard, J.P., and Dembroff, G.R., 1993, Geologic map of surficial deposits in the Seattle 30' by 60' quadrangle, Washington, U.S. Geological Survey, Open- File Report OF-93-233, 1:100,000. ASPECT CONSULTING PROJECT NO. AS210428-100  JULY 19, 2024 FINAL 15 15 6 Limitations Work for this project was performed for Carollo Engineers, Inc. (Client), and this report was prepared consistent with recognized standards of professionals in the same locality and involving similar conditions, at the time the work was performed. No other warranty, expressed or implied, is made by Aspect Consulting, LLC (Aspect). Recommendations presented herein are based on our interpretation of site conditions, geotechnical engineering calculations, and judgment in accordance with our mutually agreed-upon scope of work. Our recommendations are unique and specific to the project, site, and Client. Application of this report for any purpose other than the project should be done only after consultation with Aspect. Variations may exist between the soil and groundwater conditions reported and those actually underlying the site. The nature and extent of such soil variations may change over time and may not be evident before construction begins. If any soil conditions are encountered at the site that are different from those described in this report, Aspect should be notified immediately to review the applicability of our recommendations. It is the Client's responsibility to see that all parties to this project, including the designer, contractor, subcontractors, and agents, are made aware of this report in its entirety. At the time of this report, design plans and construction methods have not been finalized, and the recommendations presented herein are based on preliminary project information. If project developments result in changes from the preliminary project information, Aspect should be contacted to determine if our recommendations contained in this report should be revised and/or expanded upon. The scope of work does not include services related to construction safety precautions. Site safety is typically the responsibility of the contractor, and our recommendations are not intended to direct the contractor’s site safety methods, techniques, sequences, or procedures. The scope of our work also does not include the assessment of environmental characteristics, particularly those involving potentially hazardous substances in soil or groundwater. All reports prepared by Aspect for the Client apply only to the services described in the Agreement(s) with the Client. Any use or reuse by any party other than the Client is at the sole risk of that party, and without liability to Aspect. Aspect’s origina l files/reports shall govern in the event of any dispute regarding the content of electronic documents furnished to others. Please refer to Appendix D titled “Report Limitations and Guidelines for Use” for additional information governing the use of this report. We appreciate the opportunity to perform these services. If you have any questions, please call Erik Andersen at 425.772.4705. i FIGURES Highlands Park Site 1 Site 2 Site 3 Site 4 Site 5 Site 7 Lake Washington §¨¦405 Highlands ParkRenton Airport Renton NW 7th St Site 6 Data source credits: None || Basemap Service Layer Credits: King County, WA State Parks GIS, Esri, HERE, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA, NPS, USDA, City of Renton, Bureau of Land Management, Esri Canada, Esri, HERE, Garmin, GeoTechnologies, Inc., USGS, METI/NASA, EPA, USDA, Esri, NASA, NGA, USGS, FEMA, Esri, HERE, Garmin, FAO, NOAA, USGS, EPA, City of Renton, County of King, Bureau of Land Management, Esri Canada, Esri, HERE, Garmin, GeoTechnologies, Inc., Intermap, USGS, METI/NASA, EPA, Ar c G I S P r o : G : \ p r o j e c t s \ C i t y o f R e n t o n \ 2 0 2 2 R e n t o n S e w e r R e p l a c e m e n t _ 2 1 0 4 2 8 \ P r o j e c t \ 2 0 2 2 R e n t o n S e w e r R e p l a c e m e n t _ 2 1 0 4 2 8 . a p r x | | N o P r o j e c t e d C o o r d i n a t e S y s t e m | | D a t e S a v e d : 9 / 2 8 / 2 0 2 2 | | E x p o r t e d 9 / 2 8 / 2 0 2 2 1 5 : 2 1 b y b g r i m m SEP-2022 MBR / WEG CAL / WEG 210428 1 FIGURE NO. REVISED BY: BY: PROJECT NO. Site Overview Map Geotechnical Engineering Report City of Renton Sanitary Sewer Replacement Renton, Washington 0 750 1,500 Feet 0 400 Feet MAIN MAP 430 ft 358 ft ÈA ÈA ÈA ÈA ÈA ÈA Tacoma Ave N E Site 4Site 5 Site 3 Site 7 AB-01 AB-02 AB-04 AB-05 AB-06 AB-03 Data source credits: None || Basemap Service Layer Credits: Esri, NASA, NGA, USGS, FEMA, Esri Community Maps Contributors, City of Renton, King County, WA State Parks GIS, © OpenStreetMap, Microsoft, Esri, HERE, Garmin, SafeGraph, GeoTechnologies, Inc, METI/NASA, USGS, Bureau of Land Management, EPA, NPS, US Census Bureau, USDA Ar c G I S P r o : G : \ p r o j e c t s \ C i t y o f R e n t o n \ 2 0 2 2 R e n t o n S e w e r R e p l a c e m e n t _ 2 1 0 4 2 8 \ P r o j e c t \ 2 0 2 2 R e n t o n S e w e r R e p l a c e m e n t _ 2 1 0 4 2 8 . a p r x | | N A D 1 9 8 3 S t a t e P l a n e W a s h i n g t o n N o r t h F I P S 4 6 0 1 F e e t | | D a t e S a v e d : 9 / 1 2 / 2 0 2 2 | | E x p o r t e d 9 / 1 2 / 2 0 2 2 1 0 : 2 6 b y b g r i m m SEP-2022 JMM / WEG CAL / WEG 210428 2 FIGURE NO. REVISED BY: BY: PROJECT NO. Exploration Plan Geotechnical Engineering Report City of Renton Sanitary Sewer Replacement Renton, Washington Legend ÈA Proposed Boring Location Site Location 0 500 1,000 Feet EDÈA ÈÈ È È È È È È È È È È È È È È AA A A A A A A A A A A A A A A ###***ÓÓÓÈÈAA Lake Washington Renton Airport Highlands Park wtr AB-03 ATP-01 Qac Qgt Qga wtr Qg af af Ttl Qit Qlp af Qu Qit Qu Qgt Qpa Qit Qgt Qu Qac afmwtr afm Qgt BH-1 BH-2 BH-3 BH-4 BH-5 BH-6 BH-7 BH-8 BH-9 BH-10 BH-11 BH-12 BH-13 BH-14 BH-15 BH-16 Site 1 Site 2 Site 3 Site 4Site 5 Site 6 Site 7 ÈA ÈA #*Ó #*Ó#*Ó Qu Qgt B-2 B-1 HA-3 HA-2 HA-1 Puget Sound Issaquah Renton Seattle Data source credits: None || Basemap Service Layer Credits: Esri, NASA, NGA, USGS, City of Seattle, King County, WA State Parks GIS, Esri, HERE, Garmin, SafeGraph, FAO, METI/NASA, USGS, Bureau of Land Management, EPA, NPS Ar c G I S P r o : G : \ p r o j e c t s \ C i t y o f R e n t o n \ 2 0 2 2 R e n t o n S e w e r R e p l a c e m e n t _ 2 1 0 4 2 8 \ P r o j e c t \ 2 0 2 2 R e n t o n S e w e r R e p l a c e m e n t _ 2 1 0 4 2 8 . a p r x | | N o P r o j e c t e d C o o r d i n a t e S y s t e m | | D a t e S a v e d : 1 0 / 4 / 2 0 2 2 | | E x p o r t e d 1 0 / 4 / 2 0 2 2 1 1 : 0 8 b y b g r i m m OCT-2022 MBR / MAV / WEG CAL / WEG 210428 3 FIGURE NO. REVISED BY: BY: PROJECT NO. Geology Map Geotechnical Engineering Report City of Renton Sanitary Sewer Replacement Renton, Washington Geologic Unit (WA DNR 1:24,000 and 1:100,000) Quaternary Rocks and Deposits Quaternary bog, marsh, swamp, or lake deposits (Qlp) Holocene artificial fill and modified land (afm) Quaternary alluvium (Qac) Pleistocene continental glacial drift (Qga, Qpa, Qit) Pleistocene continental glacial till (Qgt) Pleistocene glacial and nonglacial deposits (Qu) Water Water (wtr) Geologic Contact (WA DNR 1:24,000 and 1:100,000) Contact, certain accurate Contact, certain approximate Contact, certain inferred Shoreline Explorations by Others ÈA Boring, Earth Consultants, Inc. #*Ó Hand Auger, Earth Consultants, Inc. ÈA Boring, Golder & Associates ÈA Boring, Aspect ED Test Pit, Aspect 0 1,000 2,000 Feet Notes: - Geologic mapping on the north side of the blue line is at 1:100,000 scale, and mapping south of the line is at 1:24,000 scale. - Some geologic unit labels in the 1:100,000-scale mapping area have been removed for consistency with Mullineaux's (1965) labels in the 1:24,000-scale area. See text for further details FIGURE VIEW 0 150 Feet NOTES: 1.Earth pressures assume no groundwater is encountered. 2.Allowable passive earth pressures include a factor of safety of 1.5. 3.Earth pressures for the braced scenarios are based on FHWA Circular No. 4 (1999) and assume active pressure conditions. 4.Active pressures are assumed to act over the full width of the retained soil and over the width of any elements embedded below the base of the wall. For soldier pile and lagging systems, passive pressures can be assumed to act over the lesser of 3 times the concreted diameter of the soldier pile or the center-to-center embedded pile spacing. 5.Earth pressure units are pounds per square foot. 6.Wall embedment should be established by the shoring designer considering global stability and 'kickout' resistance. Embedment should satisfy horizontal static equilibrium about the bottom of the pile. Min. recommended embedment is 10 feet. 7.Figure is not to scale. 8.The shoring designer should include loads from groundwater, surface surcharge loads, and jacking forces as applicable and appropriate. 210428 JMM 4 Sep-2022 -- BY: REVISED BY:PROJECT NO. FIGURE NO. CA D P a t h : \\ b h a m d i s k s t a t i o n . a s p e c t . l o c a l \ P r o j e c t s \ C i t y o f R e n t o n \ 2 0 2 2 R e n t o n S a n i t a r y S e w e r R e p l a c e m e n t \ D a t a \ A n a l y s e s \ 2 1 0 4 2 8 - E P D . d w g E P D | | D a t e S a v e d : S e p 1 2 , 2 0 2 2 6 : 5 3 a m | | U s e r : jm a r t z Geotechnical Engineering Report City of Renton Sanitary Sewer Replacement Renton, Washington Temporary Lateral Shoring Pressures RECOMMENDED TEMPORAR< EARTH PRESSURES FOR CANTILE9ERED WALL RECOMMENDED TEMPORAR< EARTH PRESSURES FOR SINGLE BRACED WALL RECOMMENDED TEMPORAR< EARTH PRESSURES FOR MULTIPLE BRACED WALL IGNORE PASSIVE RESISTANCE IN TOP 2' (TYP.) A B CE H<25' D WALL IGNORE PASSIVE RESISTANCE IN TOP 2' (TYP.) E H<25' D IGNORE PASSIVE RESISTANCE IN TOP 2' (TYP.) E H<25' D ACTI9EPASSI9E ACTI9EAPPARENTPASSI9E ACTI9EAPPARENTPASSI9E H1 2/3 H1 1/3 H 2/3 (H-H1) A BOTTOM OF EXCAVATION WALL BOTTOM OF EXCAVATION BRACE H1 TOP BRACE LOWER BRACE Hn+1 2/3 H1 2/3 Hn+1 p p =H - 1/3 H1 - 1/3 Hn+1 0.65*A*H² WALL LEGEND: H = Total excavation height, feet D = Total embedment depth, feet A, B, C, E, = Earth pressure factors, see table. RECOMMENDED EARTH PRESSURES (PSF) A B C E 38H 38H 38D 270D B C B C i APPENDIX A Subsurface Exploration Logs ASPECT CONSULTING PROJECT NO. AS210428-100  JULY 19, 2024 FINAL A-1 1 A. Subsurface Exploration Logs In July 2022, Aspect advanced six borings with a subcontracted geotechnical driller between Sites 3, 4, 5, and 7. The locations of the explorations were chosen to inform geotechnical analyses and recommendations for the sewer replacements. The locations of our field explorations are presented on Figure 2. Detailed descriptions of our field exploration methods are presented in the following sections. Holocene Drilling, Inc. (Holocene) drilled two geotechnical exploration borings (AB-01 and AB-02) on July 25, 2022, one geotechnical exploration boring (AB-04) on July 26, 2022, and three geotechnical exploration borings (AB-03, AB-05, and AB-06) on July 27, 2022. Borings AB-01, AB-02, and AB-04 were conducted using a track-mounted Diedrich D-70 turbo drill rig, and AB-03, AB-05, and AB-06 were conducted using a truck-mounted Diedrich D-70 turbo drill rig, both utilizing hollow-stem auger drilling methods. The hollow-stem auger method consists of advancing a continuous string of 5-foot-long open-flight augers and a conical hollow auger head with a 4.25-inch inner diameter and about an 6.25-inch outer diameter. A center plug was seated inside of the conical hollow auger head to ensure maximum soil removal. The augers convey soil cuttings to the surface between the annular space between the drill stem and the boring wall, leaving the hollow-stem free from soil. At sampling depth intervals, the center plug is removed, and the soil sampler is lowered to the bottom of the boring. After sampling, the center plug is replaced and drilling resumes to the next sampling depth. Soil samples were collected at 2.5-foot and 5-foot intervals using the Standard Penetration Test (SPT) method and in general accordance with ASTM D1586. The samples were collected by driving a 2-inch outside-diameter by 1⅜-inch inside-diameter, split spoon sampler 18 inches into the soil with a 140-pound automatic hammer falling 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. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils. If a total of 50 blows are recorded for a single 6-inch interval, the test is terminated, and the blow count is recorded as 50 blows for the total inches of penetration. After performing the SPT, the sampler was retrieved to the surface and opened, and the soil samples were observed, described in the field boring logs, and placed in labeled plastic jars and taken to a laboratory for further classification. Explorations AB-01, AB-02, AB-04, and AB-06, which extend to depths ranging from 31.5 to 36.5-feet bgs, were backfilled with hydrated 3/8-inch bentonite chips until approximately 3-feet bgs where they were capped with concrete. Explorations AB-03 and AB-05 were completed as standpipe groundwater monitoring wells. A detailed graphic of the exploration completion is shown on the boring logs. ASPECT CONSULTING A-2 FINAL PROJECT NO. AS210428-100  JULY 19, 2024 Aspect observed and documented soil, groundwater, and excavation characteristics for all explorations. Exploration logs were created using the Unified Soil Classification System (USCS), as defined in ASTM D2488, and standard geologic unit nomenclature. Terminology used in soil descriptions is presented in the Exploration Log key. AI P a t h : Q: \ _ A C A D S t a n d a r d s \ F I E L D R E F E R E N C E \ M A S T E R S \ E x p l o r a t i o n L o g K e y - 2 0 1 8 . a i / / u s e r : j i n m a n / / l a s t s a v e d : 1 2 / 3 1 / 2 0 1 8 “WITH SILT” or “WITH CLAY” means 5 to 15% silt and clay, denoted by a “-“ in the group name; e.g., SP-SM ● “SILTY” or “CLAYEY” means >15% silt and clay ● “WITH SAND” or “WITH GRAVEL” means 15 to 30% sand and gravel. ● “SANDY” or “GRAVELLY” means >30% sand and gravel. ● “Well-graded” means approximately equal amounts of fine to coarse grain sizes ● “Poorly graded” means unequal amounts of grain sizes ● Group names separated by “/” means soil contains layers of the two soil types; e.g., SM/ML. Soils were described and identified in the field in general accordance with the methods described in ASTM D2488. Where indicated in the log, soils were classified using ASTM D2487 or other laboratory tests as appropriate. Refer to the report accompanying these exploration logs for details. % by Weight Density³SPT² Blows/Foot Hi g h l y Or g a n i c So i l s Fi n e - G r a i n e d S o i l s - 5 0 % 1 o r M o r e P a s s e s N o . 2 0 0 S i e v e Co a r s e - G r a i n e d S o i l s - M o r e t h a n 5 0 % 1 R e t a i n e d o n N o . 2 0 0 S i e v e Gr a v e l s - M o r e t h a n 5 0 % 1 o f C o a r s e F r a c t i o n Re t a i n e d o n N o . 4 S i e v e 15 % F i n e s 5% F i n e s Sa n d s - 5 0 % 1 o r M o r e o f C o a r s e F r a c t i o n Pa s s e s N o . 4 S i e v e Si l t s a n d C l a y s Li q u i d L i m i t L e s s t h a n 5 0 % Si l t s a n d C l a y s Li q u i d L i m i t 5 0 % o r M o r e 15 % F i n e s 5% F i n e s Well-graded GRAVEL Well-graded GRAVEL WITH SAND Poorly-graded GRAVEL Poorly-graded GRAVEL WITH SAND SILTY GRAVEL SILTY GRAVEL WITH SAND CLAYEY GRAVEL CLAYEY GRAVEL WITH SAND Well-graded SAND Well-graded SAND WITH GRAVEL Poorly-graded SAND Poorly-graded SAND WITH GRAVEL SILTY SAND SILTY SAND WITH GRAVEL CLAYEY SAND CLAYEY SAND WITH GRAVEL SILT SANDY or GRAVELLY SILT SILT WITH SAND SILT WITH GRAVEL LEAN CLAY SANDY or GRAVELLY LEAN CLAY LEAN CLAY WITH SAND LEAN CLAY WITH GRAVEL ORGANIC SILT SANDY or GRAVELLY ORGANIC SILT ORGANIC SILT WITH SAND ORGANIC SILT WITH GRAVEL ELASTIC SILT SANDY or GRAVELLY ELASTIC SILT ELASTIC SILT WITH SAND ELASTIC SILT WITH GRAVEL FAT CLAY SANDY or GRAVELLY FAT CLAY FAT CLAY WITH SAND FAT CLAY WITH GRAVEL ORGANIC CLAY SANDY or GRAVELLY ORGANIC CLAY ORGANIC CLAY WITH SAND ORGANIC CLAY WITH GRAVEL PEAT and other mostly organic soils GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT Modifier Organic Chemicals BTEX =Benzene, Toluene, Ethylbenzene, Xylenes TPH-Dx =Diesel and Oil-Range Petroleum Hydrocarbons TPH-G =Gasoline-Range Petroleum Hydrocarbons VOCs =Volatile Organic Compounds SVOCs =Semi-Volatile Organic Compounds PAHs =Polycyclic Aromatic Hydrocarbon Compounds PCBs =Polychlorinated Biphenyls GEOTECHNICAL LAB TESTSMC=Natural Moisture Content PS =Particle Size Distribution FC =Fines Content (% < 0.075 mm)GH =Hydrometer TestAL=Atterberg Limits C =Consolidation Test Str =Strength Test OC =Organic Content (% Loss by Ignition) Comp =Proctor Test K =Hydraulic Conductivity Test SG =Specific Gravity Test RCRA8 =As, Ba, Cd, Cr, Pb, Hg, Se, Ag, (d = dissolved, t = total) MTCA5 =As, Cd, Cr, Hg, Pb (d = dissolved, t = total) PP-13 =Ag, As, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, Tl, Zn (d=dissolved, t=total) CHEMICAL LAB TESTS PID =Photoionization Detector Sheen =Oil Sheen Test SPT 2 =Standard Penetration Test NSPT =Non-Standard Penetration Test DCPT =Dynamic Cone Penetration Test <1 =Subtrace 1 to <5 =Trace 5 to 10 =Few Dry =Absence of moisture, dusty, dry to the touch Slightly Moist =Perceptible moisture Moist =Damp but no visible water Very Moist =Water visible but not free draining Wet = Visible free water, usually from below water table COMPONENT DEFINITIONSDescriptive Term Size Range and Sieve Number Boulders = Larger than 12 inches Cobbles =3 inches to 12 inches Coarse Gravel =3 inches to 3/4 inches Fine Gravel =3/4 inches to No. 4 (4.75 mm) Coarse Sand =No. 4 (4.75 mm) to No. 10 (2.00 mm) Medium Sand =No. 10 (2.00 mm) to No. 40 (0.425 mm) Fine Sand =No. 40 (0.425 mm) to No. 200 (0.075 mm) Silt and Clay =Smaller than No. 200 (0.075 mm) Metals ESTIMATED1 PERCENTAGE MOISTURE CONTENT RELATIVE DENSITY CONSISTENCY GEOLOGIC CONTACTS Very Loose =0 to 4 ≥2' Loose =5 to 10 1' to 2' Medium Dense =11 to 30 3" to 1' Dense =31 to 50 1" to 3" Very Dense => 50 < 1" Consistency³ Very Soft =0 to 1 Penetrated >1" easily by thumb. Extrudes between thumb & fingers. Soft =2 to 4 Penetrated 1/4" to 1" easily by thumb. Easily molded. Medium Stiff =5 to 8 Penetrated >1/4" with effort by thumb. Molded with strong pressure. Stiff =9 to 15 Indented ~1/4" with effort by thumb. Very Stiff =16 to 30 Indented easily by thumbnail. Hard => 30 Indented with difficulty by thumbnail. Non-Cohesive or Coarse-Grained Soils SPT² Blows/Foot Observed and Distinct Observed and Gradual Inferred 1.Estimated or measured percentage by dry weight 2.(SPT) Standard Penetration Test (ASTM D1586) 3.Determined by SPT, DCPT (ASTM STP399) or other field methods. See report text for details. % by Weight Modifier 15 to 25 =Little 30 to 45 =Some >50 =Mostly Penetration with 1/2" Diameter Rod Manual Test FIELD TESTS Cohesive or Fine-Grained Soils Exploration Log Key 22 32 30 14 30 45 27 50/6" 15 22 25 12 30 50/6" Boring backfilled w/ bentonite chips to 3 ft bgs and capped with concrete PS FC=35.4% S1 S 2 S 3 S 4 S5 PAVEMENT ASPHALT; 5 inches of Asphalt LODGEMENT TILL SILTY SAND (SM); very dense, slightly moist, gray brown; fine to coarse sand; trace subrounded fine gravel. Becomes very moist. Becomes dense. OLDER GLACIOFLUVIAL DEPOSITS SAND WITH SILT AND GRAVEL (SP-SM); very dense, very moist, brown; fine to coarse sand; subangular to rounded fine to coarse gravel; 0.5" to 1.5" silt and fine sand interbeds. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 390 385 380 AB-01 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) No Water Encountered 47.4986, -122.1759 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-01 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Sa m p l e Ty p e Elev. (feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 Renton, Washington 98056, See Figure 2 ExplorationLog Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 1 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 5 10 15 7/25/2022 Project Address & Site Specific Location 395' (est) Plastic Limit 10 20 30 400 50 43 50/6" 20 22 33 18 26 50/6" PS FC=10.6% S6 S7 A S 7 B S8 OLDER GLACIOFLUVIAL DEPOSITS SAND WITH SILT AND GRAVEL (SP-SM); very dense, very moist, brown; fine to coarse sand; subangular to rounded fine to coarse gravel; 0.5" to 1.5" silt and fine sand interbeds. (continued) SAND (SP); very dense, moist, brown; fine to coarse sand; trace fines. SILTY SAND (SM); very dense, moist, brown; fine to medium sand, trace coarse sand. Bottom of exploration at 31.5 ft. bgs. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 370 365 360 AB-01 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) No Water Encountered 47.4986, -122.1759 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-01 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Sa m p l e Ty p e Elev. (feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 25 30 35 Renton, Washington 98056, See Figure 2 ExplorationLog Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 2 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 25 30 35 7/25/2022 Project Address & Site Specific Location 395' (est) Plastic Limit 10 20 30 400 50 21 22 25 26 15 8 4 8 4 8 12 15 11 15 15 Boring backfilled w/ bentonite chips to 3 ft bgs and capped with concrete PS FC=17.2% S1 S 2 S3 S 4 S 5 PAVEMENT ASPHALT; 5.5 inches of asphalt FILL SILTY SAND WITH GRAVEL (SM); dense, slightly moist, brown; fine to medium sand, trace coarse sand; subangular to subrounded fine gravel. Becomes medium dense, red brown, and with coarse sand. OLDER GLACIOFLUVIAL DEPOSITS SILTY SAND (SM); medium dense, moist, red brown; fine to medium sand, trace coarse sand; trace subangular to rounded fine to coarse gravel; 0.5" to 1" silt and fine sand interbeds. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 380 375 370 365 AB-02 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) No Water Encountered 47.4951, -122.1756 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-02 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Sa m p l e Ty p e Elev. (feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 Renton, Washington 98056, See Figure 2 ExplorationLog Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 1 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 5 10 15 7/25/2022 Project Address & Site Specific Location 381' (est) Plastic Limit 10 20 30 400 50 13 12 13 15 13 14 11 13 15 11 18 32 PS FC=13.3% S6 S7 S8 S9 OLDER GLACIOFLUVIAL DEPOSITS SILTY SAND (SM); medium dense, moist, red brown; fine to medium sand, trace coarse sand; trace subangular to rounded fine to coarse gravel; 0.5" to 1" silt and fine sand interbeds. (continued) Becomes without gravel and without silt and fine sand interbeds. SAND WITH SILT (SP-SM); very dense, very moist, brown; fine to coarse sand; trace subangular to rounded fine to coarse gravel. Bottom of exploration at 36.5 ft. bgs. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 360 355 350 345 AB-02 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) No Water Encountered 47.4951, -122.1756 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-02 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Sa m p l e Ty p e Elev. (feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 25 30 35 Renton, Washington 98056, See Figure 2 ExplorationLog Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 2 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 25 30 35 7/25/2022 Project Address & Site Specific Location 381' (est) Plastic Limit 10 20 30 400 50 10 12 21 5 12 21 6 18 22 6 6 8 14 32 39 Flush mount monument set in concrete. 3/8-inch bentonite chips. 2-inch diam. Sch 40 PVC riser 2x12 silica sand filter pack PS FC=11% PS FC=18.6% S1 S 2 S 3 S 4 S5 PAVEMENT ASPHALT; 5 inches of asphalt RECESSIONAL OUTWASH SAND WITH SILT (SP-SM); dense, slightly moist, red brown to light brown; fine to coarse sand; subtrace subangular to subrounded fine gravel; subtrace organics. Becomes brown, moist, with mostly fine to medium sand and trace coarse sand, and without gravel. Becomes with 0.5" to 2" silt and fine sand interbeds. Becomes medium dense and with iron oxide staining. OLDER GLACIOFLUVIAL DEPOSITS SILTY SAND (SM); very dense, slightly moist, light brown; fine to coarse sand; subtrace organics; iron oxide staining; silt and sand interbeds. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 370 365 360 355 AB-03 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) No Water Encountered 47.4933, -122.1723 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-03 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Ecology Well Tag No. BPK 031 Sa m p l e Ty p e Elev. (feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 Renton, Washington 98056, See Figure 2 ExplorationLog Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 1 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 5 10 15 7/27/2022 Project Address & Site Specific Location 372' (est) Plastic Limit 10 20 30 400 50 8 9 12 12 18 22 32 39 30 2-inch Sch 40 PVC 0.010-inch slot screen Threaded cap PS FC=14.7% S6 S7 S8 OLDER GLACIOFLUVIAL DEPOSITS SILTY SAND (SM); very dense, slightly moist, light brown; fine to coarse sand; subtrace organics; iron oxide staining; silt and sand interbeds. (continued) Becomes medium dense and without coarse sand. SAND WITH SILT (SP-SM); dense, moist to very moist, brown; fine to medium sand, few coarse sand; subtrace subangular to rounded fine gravel. SILTY SAND WITH GRAVEL (SM); very dense, moist, brown; fine to medium sand, few coarse sand; subangular to rounded fine to coarse gravel, fine sand interbeds. Bottom of exploration at 31.5 ft. bgs. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 350 345 340 335 AB-03 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) No Water Encountered 47.4933, -122.1723 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-03 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Ecology Well Tag No. BPK 031 Sa m p l e Ty p e Elev. (feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 25 30 35 Renton, Washington 98056, See Figure 2 ExplorationLog Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 2 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 25 30 35 7/27/2022 Project Address & Site Specific Location 372' (est) Plastic Limit 10 20 30 400 50 12 16 24 14 18 20 20 50/6" 14 23 29 12 17 16 Boring backfilled w/ bentonite chips to 3 ft bgs and capped with concrete PS FC=30.8% Blows (non-SPT) =9, 18, 32 S1 S 2 S 3 S4 S5 PAVEMENT ASPHALT; 4.5 inches of Asphalt TILL SILTY SAND WITH GRAVEL (SM); very dense, slightly moist, gray brown; fine to coarse sand, mostly fine; subrounded fine gravel. Becomes very dense. No recovery from SPT due to gravel. OLDER GLACIOFLUVIAL DEPOSITS SAND WITH SILT (SP-SM); dense, moist, brown; fine to coarse sand; subtrace subangular to rounded fine to coarse gravel; 0.5" to 1.5" silt and fine sand interbeds. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 385 380 375 370 AB-04 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) Split Barrel 3" X 2.375" No Water Encountered 47.4922, -122.1742 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-04 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Sa m p l e Ty p e Elev. (feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 Renton, Washington 98056, See Figure 2 ExplorationLog Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 1 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 5 10 15 7/26/2022 Project Address & Site Specific Location 387' (est) Plastic Limit 10 20 30 400 50 14 27 50/0" 12 23 34 15 50/6" PS FC=28.7% S6 S7 S8 SILTY SAND WITH GRAVEL (SM); very dense, moist to very moist, brown; fine to coarse sand; subangular to rounded fine to coarse gravel; 0.5" to 1.5" silt and fine sand interbeds. Becomes with mostly fine to medium sand, trace coarse sand, and without gravel. SAND WITH SILT AND GRAVEL (SP-SM); very dense, gray brown, moist; fine to coarse sand; subrounded to rounded fine to coarse gravel. Bottom of exploration at 31.5 ft. bgs. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 365 360 355 350 AB-04 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) Split Barrel 3" X 2.375" No Water Encountered 47.4922, -122.1742 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-04 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Sa m p l e Ty p e Elev. (feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 25 30 35 Renton, Washington 98056, See Figure 2 ExplorationLog Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 2 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 25 30 35 7/26/2022 Project Address & Site Specific Location 387' (est) Plastic Limit 10 20 30 400 50 7 24 28 12 22 24 13 27 45 50/6" 50/6" Flush mount monument set in concrete. 3/8-inch bentonite chips. 2-inch diam. Sch 40 PVC riser 2x12 silica sand filter pack PS FC=46.1% 9/6/2022 S1 S 2 S 3 S 4 S5 PAVEMENT ASPHALT; 4 inches of Asphalt FILL SAND WITH SILT (SP-SM); very dense, slightly moist, brown to gray brown; fine to coarse sand; trace subrounded fine gravel, 3" red orange iron oxide stained fine sand. LODGEMENT TILL SILTY SAND (SM); dense, moist, gray; fine to coarse sand, mostly fine; subtrace subangular to subrounded fine gravel. Becomes very dense and very moist. Becomes with coarse sand and trace subrounded fine to coarse gravel. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 415 410 405 400 AB-05 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) 47.4931, -122.1654 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-05 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Ecology Well Tag No. BPK 032 Sa m p l e Ty p e Elev. (feet) Static Water Level Liquid Limit Geotechnical Exploration Log 5 10 15 Renton, Washington 98056, See Figure 2 ExplorationLog 27.8' (Static) Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 1 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 5 10 15 7/27/2022 Project Address & Site Specific Location 417' (est) Plastic Limit 10 20 30 400 50 50/3" 50/4" 50/5" 2-inch Sch 40 PVC 0.010-inch slot screen Threaded cap 7/27/2022 At time of diver installation. S6 S7 S8 LODGEMENT TILL SILTY SAND (SM); dense, moist, gray; fine to coarse sand, mostly fine; subtrace subangular to subrounded fine gravel. (continued) Bottom of exploration at 31.5 ft. bgs. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 395 390 385 380 AB-05 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) 47.4931, -122.1654 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-05 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Ecology Well Tag No. BPK 032 Sa m p l e Ty p e Elev. (feet) Static Water Level Liquid Limit Geotechnical Exploration Log 25 30 35 Renton, Washington 98056, See Figure 2 ExplorationLog 27.8' (Static) Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 2 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 25 30 35 7/27/2022 Project Address & Site Specific Location 417' (est) Plastic Limit 10 20 30 400 50 4 11 24 9 21 22 6 13 30 25 50/6" 26 50/4" Boring backfilled w/ bentonite chips to 3 ft bgs and capped with concrete PS FC=35.4% S1 S 2 S 3 S 4 S5 PAVEMENT ASPHALT; 4.5 inches of Asphalt FILL SAND WITH SILT (SP-SM); dense, slightly moist, brown; fine to coarse sand; subtrace subrounded fine gravel. LODGEMENT TILL SILTY SAND (SM); dense, moist, gray brown; fine to coarse sand, mostly fine; subtrace subrounded fine gravel. Becomes very dense and very moist. SILTY SAND WITH GRAVEL (SM); very dense, moist, gray brown; fine to coarse sand, mostly fine; subangular to subrounded fine gravel; trace coarse gravel. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 415 410 405 400 AB-06 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) No Water Encountered 47.4922, -122.1657 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-06 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Sa m p l e Ty p e Elev. (feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 5 10 15 Renton, Washington 98056, See Figure 2 ExplorationLog Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 1 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 5 10 15 7/27/2022 Project Address & Site Specific Location 419' (est) Plastic Limit 10 20 30 400 50 53/3" 50/4" 50/3" S6 S7 S8 SILTY SAND WITH GRAVEL (SM); very dense, moist, gray brown; fine to coarse sand, mostly fine; subangular to subrounded fine gravel; trace coarse gravel. (continued) Bottom of exploration at 31.5 ft. bgs. Operator Work Start/Completion Dates Blows/foot Water Content (%) Equipment Legend Contractor 395 390 385 380 AB-06 Tests Rotary drill rig 8.5" OD X 4.25" IDHollow-Stem Auger Holocene Drilling Exploration Method(s) See Exploration Log Key for explanation of symbols Sample Type/ID Depth to Water (Below GS) Description NA Split Barrel 2" X 1.375" (SPT) No Water Encountered 47.4922, -122.1657 (est) Ground Surface Elev. (NAVD88) Exploration Notes and Completion Details Blows/6" Coordinates (Lat,Lon WGS84) Autohammer; 140 lb hammer; 30" drop Logged by: JMM Approved by: MvA AB-06 2022 Sanitary Sewer Replacement - 210428 Depth (feet) Material Type Chris Sa m p l e Ty p e Elev. (feet) No Water Encountered Liquid Limit Geotechnical Exploration Log 25 30 35 Renton, Washington 98056, See Figure 2 ExplorationLog Exploration Number No Soil Sample Recovery Wa t e r Le v e l Sheet 2 of 2 Depth (ft) Sampling Method NE W S T A N D A R D E X P L O R A T I O N L O G T E M P L A T E P : \ G I N T W \ P R O J E C T S \ R E N T O N S E W E R 2 1 0 4 2 8 . G P J O c t o b e r 3 , 2 0 2 2 Top of Casing Elev. (NAVD88) 25 30 35 7/27/2022 Project Address & Site Specific Location 419' (est) Plastic Limit 10 20 30 400 50 1 APPENDIX B Geotechnical Laboratory Analysis Results PROJECT NO. AS210428-100  JULY 19, 2024 FINAL B-1 1 B. Geotechnical Laboratory Analysis Results Hayre McElroy & Associates, LLC (HMA) performed laboratory testing on select soil samples obtained from the explorations to characterize index and engineering properties of materials at the Site. Soil samples used in the testing program were collected from the soil borings. The results of the geotechnical laboratory testing are presented here in Appendix B, following the summary of geotechnical laboratory testing methods that is outlined below. Soil samples from the explorations were visually classified in the field and then taken to our laboratory, where the classifications were verified in a controlled environment. Field and laboratory observations included density/consistency, moisture condition, and grain size and plasticity estimates. The classifications of selected samples were checked by grain-size analysis and plasticity index testing. Classifications were made in general accordance with the Unified Soil Classification System (USCS), ASTM D2488. Soil Moisture contents were determined for samples recovered in the explorations in general accordance with ASTM D2216, as soon as possible following their arrival to the laboratory. Moisture contents are shown on the exploration logs in Appendix A. Particle- size analyses were performed on select soil samples in general accordance with ASTM C136 and ASTM D1140 to determine their grain-size distributions. The Sieve Analysis of Fine and Coarse Aggregates was performed by wet sieve analyses, determining percentages (by weight) of the sample passing a series of sieves from the 1-inch sieve, down to the No. 200 (0.75 mm) sieve. The results of the particle-size analyses are presented in this appendix. Grain-size analysis results for full sieve and percent passing No. 200 sieve are presented in numerical order based on boring and sample number. APPENDIX C Previous Explorations by Others ^ Site Location Map Technical Memorandum Monroe Avenue NE Storm System Improvements City of Renton, Washington FIGURE NO. 1MAY-2020 PROJECT NO. 190398 BY: EAC / ETB REVISED BY: - - - 0 2,000 4,000 Feet ! ! ! #! ! ! ! !( W A S H I N G T O N SITE LOCATION Bellingham Olympia Port Angeles Seattle Spokane Tacoma Wenatchee Yakima ! ! ! ! # !( SITE LOCATION ElliottBay Bellevue Kent Renton Seattle Basemap Layer Credits || Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and the GIS User Community Copyright:(c) 2014 Esri SITE LOCATION D,,,,D ,,,, DD ,,,, ,,,, !D !D !D !D!D ,,,,,, !!! !D!D ,,,, ") ") ") ") ") ") ") ") ")!( ") ") ") ") ") ") ") ") ")") !( ") !( ") ") ") !( ") ") !( !( ") ") !( !( ") !( !( ") ") !( !( !( ") !( ") ") !( ") ") !( ") ") !( ") ") ") !( ") ") ") !( !( ") ") ") ") !( ") !( ®f ®f !( !( !( ®f ") ") ") ") ")") ")!( !( ") !( ") ") !( ")") ") ") !( ") !("/ ") ") ")") ") ") ") ") ") !( ") ") ")") ") !( ") ") ") !( ") !( ") ") ") !( ") ") ") ") !( ") ") ") ") !("/ !( ") !(!( ") !( !( !( !( ") ") ") ") ")") !( !( ") ") ") ") ") !( !( ") ") ") ") ") ") ") ") !(!( !(!(!( !(!( !( !(!( !(!( !( !( !(!(!(!( !( !( !( !( !( !( !( !( !( !( !( !( !(!(!( !(!(!(!(!(!(!(!( !( !( !( !( !( !( !( !(!(!( !( !( !( !( !( !( !(!( !(!(!( !( !( !( !( !(!U !!( !( !!( !!( !!( !!( !!( !!( !!( !\ @A @A ED ED @A Upper Balch Pit AB-01 AB-02 ATP-01 ATP-02 AB-03 FIGURE NO. 2DEC-2020 PROJECT NO. 190398 BY: EAC / ETB / WEG REVISED BY: EAC Exploration Site Plan Technical Memorandum Monroe Avenue NE Storm System Improvements City of Renton, Washington 0 200 400100 Feet @A Boring ED Test Pit !\Existing Flow Control BMP !!(Outlet !U Lift Station ")Inlet !(Manhole "/Utility Vault ®f Unknown Structure ,,Pipe Approximate Site Boundary 301 Monroe Ave. NE Project Boundary Project Boundary (1000-ft Buffer) Basemap Layer Credits || EagleView Technologies, Inc. APPENDIX A Subsurface Explorations ASPECT CONSULTING A. Subsurface Exploration Program The field exploration programs consisted of drilling a total of drilling two borings (designated AB-01 and AB-02) on February 20, 2020, another boring (AB-03) on November 24, 2020 and excavating two test pits (designated ATP-01 and ATP-02) on April 6 and 7, 2020. Borings were advanced using hollow stem auger (HSA) between 34 feet and 76.5 feet bgs. Test pits were excavated using a track mounted excavator. The locations of the explorations are shown on Figure 2 and the exploration logs are included in this appendix. An Aspect geologist was present throughout the field exploration program to observe the drilling procedure, assist in sampling, and to prepare descriptive logs of the exploration. Soils were classified in general accordance with ASTM International (ASTM) D2488, Standard Practice for Description and Identification of Soils (Visual-Manual Procedure). The summary exploration logs represent our interpretation of the contents of the field log. The stratigraphic contacts shown on the individual summary logs represent the approximate boundaries between soil types; actual transitions may be more gradual. The subsurface conditions depicted are only for the specific date and locations reported, and therefore, are not necessarily representative of other locations and times. A.1. Soil Borings Two geotechnical borings (designated AB-01 through AB-02) were drilled to 34 and 35.4 bgs with hollow stem augers by Holocene Drilling using a rubber tire-mounted Diedrich 120 drill rig equipped with a 300-pound automatic-safety hammer. A third geotechnical borings (designated AB-03) was drilled to 76.5 bgs with hollow stem augers by Holt Services using a rubber track-mounted LD-10T Rotary Drill Rig equipped with a 140- pound automatic-safety hammer. Select samples were collected using the Standard Penetration Test (SPT) in general accordance with ASTM D1586. Samples were obtained at 2.5 feet to 5 feet intervals below bgs to the depths explored, using the SPT in general accordance with ASTM D1586. The sampler types used are depicted on the exploration logs in this appendix. The SPT method involves driving a 2-inch-outside-diameter split-barrel sampler with a 300-pound (or 140 pound for AB-03) hammer free-falling from a distance of 30 inches. To obtain better sample recovery for anticipated coarse sand and gravel, a 3-inch modified sampler was used. 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. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils. If a total of 50 blows are recorded for a single 6-inch interval, the test is terminated and the blow count is recorded as 50 blows for the total inches of penetration. Samples were placed in labeled plastic jars and taken to a laboratory for further classification. ASPECT CONSULTING The monitoring wells installed in AB-01 through AB-03 were backfilled with sand through the screen interval, followed by bentonite, and cement grout, installing a 2-inch diameter monitoring well, and completing with a flush-mounted monument. A.2. Test Pits Test pits ATP-01 through ATP-02 were excavated using a Cat 312 E track mounted excavator. The excavation was completed by On-Track Excavating, under the direction of Aspect Consulting, LLC. The locations of the test pits are shown on Figure 2 in the main body of the report. Summary test pit logs are included in this appendix. Samples were obtained from select soil units to aid in the determination of engineering properties of the subsurface materials. The relative density/consistency of the soils was evaluated qualitatively with a 0.5-inch-diameter steel T-probe and observation of excavation difficulty at various depth intervals within the test pits. The test pits were backfilled with the native soils and compacted with the excavator bucket in 1-foot-thick lifts. Detailed descriptions of the subsurface conditions encountered in our explorations, as well as the depths where characteristics of the soils changed, are indicated on the test pit logs. The depths indicated on the log where conditions changed may represent gradational variations between soil types. Soils were classified in general accordance with the ASTM D2488, Standard Practice for Description and Identification of Soils (Visual and Manual Procedure). A key to the symbols and terms used on the logs is provided on Figure A-1. 1 APPENDIX D Report Limitations and Guidelines for Use ASPECT CONSULTING REPORT LIMITATIONS AND GUIDELINES FOR USE Geoscience is Not Exact The geoscience practices (geotechnical engineering, geology, and environmental science) are far less exact than other engineering and natural science disciplines. It is important to recognize this limitation in evaluating the content of the report. If you are unclear how these "Report Limitations and Guidelines for Use" apply to your project or property, you should contact Aspect Consulting, LLC (Aspect). This Report and Project-Specific Factors Aspect’s services are designed to meet the specific needs of our clients. Aspect has performed the services in general accordance with our agreement (the Agreement) with the Client (defined under the Limitations section of this project’s work product). Thi s report has been prepared for the exclusive use of the Client. This report should not be applied for any purpose or project except the purpose described in the Agreement. Aspect considered many unique, project-specific factors when establishing the Scope of Work for this project and report. You should not rely on this report if it was: •Not prepared for you; •Not prepared for the specific purpose identified in the Agreement; •Not prepared for the specific subject property assessed; or •Completed before important changes occurred concerning the subject property, project, or governmental regulatory actions. If changes are made to the project or subject property after the date of this report, Aspect should be retained to assess the impact of the changes with respect to the conclusions contained in the report. Reliance Conditions for Third Parties This report was prepared for the exclusive use of the Client. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against liability claims by third parties with whom there would otherwise be no contractual limitations. Within the limitations of scope, schedule, and budget, our services have been executed in accordance with our Agreement with the Client and recognized geoscience practices in the same locality and involving similar conditions at the time this report was prepared Property Conditions Change Over Time This report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by events such as a change in property use or occupancy, or by natural events, such as floods, earthquakes, slope instability, or groundwater fluctuations. If any of the described events may have occurred following the issuance of the report, you should contact Aspect so ASPECT CONSULTING 3 that we may evaluate whether changed conditions affect the continued reliability or applicability of our conclusions and recommendations. Geotechnical, Geologic, and Environmental Reports Are Not Interchangeable The equipment, techniques, and personnel used to perform a geotechnical or geologic study differ significantly from those used to perform an environmental study and vice versa. For that reason, a geotechnical engineering or geologic report does not usually address any environmental findings, conclusions, or recommendations (e.g., about the likelihood of encountering underground storage tanks or regulated contaminants). Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding the subject property. We appreciate the opportunity to perform these services. If you have any questions, please contact the Aspect Project Manager for this project.