Loading...
HomeMy WebLinkAboutD_Hirani Retaining Wall Tract Restoration CAE_v3DEPARTMENT OF COMMUNITY AND ECONOMIC DEVELOPMENT D_Hirani Retaining Wall Tract Restoration CAE_v3 (002) PLANNING DIVISION CERTIFICATE OF EXEMPTION FROM CRITICAL AREAS REGULATIONS EVALUATION FORM & DECISION DATE OF DECISION: August 26, 2021 PROJECT NUMBER: LUA21-000238, CAE PROJECT NAME: Hirani Residence Retaining Wall-Tract Restoration PROJECT MANAGER: Brittany Gillia, Assistant Planner APPLICANT: Ashifa Nurani 2708 Williams Ave N, Renton, WA 98056 OWNER: Clover Creek Homeowners Association 1125 N 27th Pl, Renton WA 98056 CONTACT: Stephen Siebert, AESI 911 5th Ave, Kirkland, WA 98033 PROJECT LOCATION: APN 164450-TRCT (located east of 2708 Williams Ave N) PROJECT DESCRIPTION: The applicant is requesting approval of a Critical Areas Exemption in order to restore land altered by unpermitted retaining wall encroachments in Tract A (APN 164450-TRCT) of the Clover Creek subdivision as documented in open code case Warning of Violation (WOV): CODE19-000641 (Attachment A). The site is a Native Growth Protection Easement (NGPE) located within the Residential-8 (R-8) zone and is approximately 78,016 square feet (1.79 acres). According to submitted materials, the mitigation area would extend up to 24.5 feet away from the shared western property line between the tract and 2708 Williams Ave N (APN 164450-0170) and would revegetate approximately 680 square feet of the NGPE Tract (Attachment B). A geotechnical report prepared by Associated Earth Sciences Inc. was submitted with the project application (Attachment C). The restoration scope would include removal of the unpermitted concrete stairs and block retaining walls encroaching on the NGPE, as well as regrading of the area to match adjacent grades, compacting loosened surficial native soils with small portable equipment to a firm condition, covering the impacted area with a layer of topsoil, planting Creeping Red Fescue grass seed along the western edge of the parcel, and covering the area after seeding with an erosion control fabric to prevent surficial erosion from occurring during heavy rainfall until the grass seed grows. Creeping Red Fescue is a grass commonly used for erosion control and is often used for stabilizing waterways, slopes, banks, cuts, and fills. According to the exploration borings detailed in the geotechnical report, the site is noted to have a presence of fill soils from 2 to 7 feet, which generally consists of loose to very loose, moist to very moist, fine to coarse sand with trace to some silt, trace gravel, and trace organics. The exploration borings also encountered lose to medium dense, moist, brown to grayish brown, fine to course DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 City of Renton Department of Community & Economic Development Certificate of Exemption From Critical Areas Regulations Hirani Residence Retaining Wall-Tract Restoration LUA21-000238, CAE Permit Date: August 26, 2021 Page 2 of 3 D_Hirani Retaining Wall Tract Restoration CAE_v3 (002) sand with trace silt and trace gravel interpreted as Vashon recessional outwash. Based on the findings, the report recommends limiting earthwork to seasonally drier periods, using silt fences, and straw mulch in exposed areas. CRITICAL AREA: Moderate Landslide Hazard, High Erosion Hazard, and Regulated Slopes (>25% & <=40%) EXEMPTION JUSTIFICATION: RMC4-3-050 C: EXEMPT, PROHIBITED AND NONCONFORMING ACTIVITIES: Activities taking place in critical areas and their associated buffers and listed in the “Exempt Activities- Permitted Within Critical Areas and Associated Buffers” table are exempt from the applicable provisions of Section 4-3-050, provided this letter of exemption has been issued. Approved Restoration/Mitigation is an exempt activity for Geologic Hazard Areas per RMC 4-3-050C.3.a.iii Approved Restoration/Mitigation: Any critical area and/or buffer restoration or other mitigation activities which have been approved by the City. FINDINGS: The proposed development is consistent with the following findings pursuant to RMC section 4-3-050C.2.d: i. The activity is not prohibited by this or any other provision of the Renton Municipal Code or State or Federal law or regulation; ii. The activity will be conducted using best management practices as specified by industry standards or applicable Federal agencies or scientific principles; Staff Comment: The geotechnical report states that the fill occupying the top 2 to 7 feet of earth is currently too loose to be used for development, therefore staff recommends as a condition of approval that the applicant consult with a geotechnical engineer or other licensed professional for recommendations on best management practices, such as selective earth compaction, to reduce chances of erosion and for the creeping red fescue to properly establish itself as a soil stabilizing groundcover. iii. Impacts are minimized and, where applicable, disturbed areas are immediately restored; iv. Where water body or buffer disturbance has occurred in accordance with an exemption during construction or other activities, revegetation with native vegetation shall be required; Staff Comment: The disturbed critical area is located in a Native Growth Protection Easement, therefore staff recommends as a condition of approval that the applicant plant a cultivar of Creeping Red Fescue native to the Pacific Northwest. v. If a hazardous material, activity, and/or facility that is exempt pursuant to this Section has a significant or substantial potential to degrade groundwater quality, then the Administrator may require compliance with the Wellhead Protection Area requirements of this Section otherwise relevant to that hazardous material, activity, and/or facility. Such determinations will be based upon site and/or chemical-specific data. DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 City of Renton Department of Community & Economic Development Certificate of Exemption From Critical Areas Regulations Hirani Residence Retaining Wall-Tract Restoration LUA21-000238, CAE Permit Date: August 26, 2021 Page 3 of 3 D_Hirani Retaining Wall Tract Restoration CAE_v3 (002) DECISION: An exemption from the Critical Areas Regulations is hereby Approved with Conditions* and subject to the following conditions: *CONDITIONS OF APPROVAL: 1. The applicant shall consult with a geotechnical engineer or other licensed professional for recommendations on best management practices for plantings to reduce soil erosion and to allow the creeping red fescue to properly establish itself as a soil stabilizing groundcover. 2. The applicant shall restore the Native Growth Protection Easement (Tract A) with a cultivar of Creeping Red Fescue that is native to the Pacific Northwest. The restoration plantings shall be inspected at time of building permit inspection for the remaining work at 2708 Williams Ave N that is being permitted in response to CODE19-000641. SIGNATURE & DATE OF DECISION: ________________________________________ ____________________________________ Vanessa Dolbee, Planning Director Date RECONSIDERATION: Within 14 days of the decision date, any party may request that the decision be reopened by the approval body. The approval body may modify his decision if material evidence not readily discoverable prior to the original decision is found or if he finds there was misrepresentation of fact. After review of the reconsideration request, if the approval body finds sufficient evidence to amend the original decision, there will be no further extension of the appeal period. Any person wishing to take further action must file a formal appeal within the 14-day appeal time frame. APPEALS: This administrative land use decision will become final if not appealed in writing to the Hearing Examiner on or before 5:00 PM on September 9, 2021. An appeal of the decision must be filed within the 14-day appeal period (RCW 43.21.C.075(3); WAC 197-11-680). Due to the ongoing state of emergency enacted by Governor’s Proclamation 20-05, the City Clerk’s Office is working remotely. For that reason, appeals must be submitted electronically to the City Clerk at cityclerk@rentonwa.gov or delivered to City Hall 1st floor Lobby Hub only on Tuesdays and/or Wednesdays. The appeal fee, normally due at the time an appeal is submitted, will be collected at a future date if your appeal is submitted electronically. Appeals to the Hearing Examiner are governed by RMC 4-8-110 and additional information regarding the appeal process may be obtained from the City Clerk’s Office, cityclerk@rentonwa.gov. EXPIRATION: Five (5) years from the date of decision (date signed). Attachments: WOV: CODE19-000641, Site Plan, Geotechnical Report, HOA Correspondence cc: Kevin Louder, Code Compliance Inspector DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 8/26/2021 | 9:35 AM PDT ATTACHMENT ADocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 ATTACHMENT B DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Kirkland | Tacoma | Mount Vernon 425-827-7701 | www.aesgeo.com December 1, 2020 Project No. 20190438E001 Rick Hirani 2708 Williams Avenue North Renton, Washington 98056 Subject: Geotechnical Engineering Report Hirani Residence Retaining Wall 2708 Williams Avenue North Renton, Washington Dear Mr. Hirani: This letter-report summarizes the findings of the subsurface exploration and geotechnical engineering study recently completed for the above-referenced project. Our work has been completed in general accordance with our proposal, dated November 11, 2019, and discussions with you, and in accordance with generally accepted geotechnical engineering practices. This letter-report was prepared for the exclusive use of Mr. Rick Hirani and his authorized agents, for specific application to this project. No other warranty, express or implied, is made. SITE AND PROJECT DESCRIPTION The site is an existing single-family residence located at 2708 Williams Avenue in Renton, Washington as shown on the “Vicinity Map,” Figure 1. The site is bounded to the north and south by single-family residences, to the west by a cul-de-sac, and to the east by an undeveloped tract owned by the homeowners association (HOA) of the subdivision. The lot comprises a relatively level portion where the residence is situated, western-sloping driveway, and backyard containing partially constructed terraced wall composed of PisaLite® blocks. A rockery wall up to about 10 feet tall is located near the northern property boundary. A rockery wall up to about 6 feet tall is located near the southern property boundary. The terraced walls are situated between the two rockery walls. According to the City of Renton (City), the site contains regulated slopes classified as landslide hazard areas and erosion hazard areas. The site prior to wall construction is shown on the “Existing Site Plan,” Figure 2. We understand that a previous contractor constructed the majority of the terraced walls ranging from 3 to 4 feet tall using PisaLite blocks without a building permit. Prior to wall completion, the contractor was terminated. The contractor constructed stairs that connect the ATTACHMENT C DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Hirani Residence Retaining Wall Renton, Washington Geotechnical Engineering Report December 1, 2020 ASSOCIATED EARTH SCIENCES, INC. JG/ms - 20190438E001-3 Page 2 terraced walls and portions of the upper walls which extend off your property onto the adjacent undeveloped tract owned by the HOA for your residential development. Western Landscape and Pavers took over construction of the project but was ordered to stop work by the City due to lack of a building permit. We reviewed the current improvement plans developed by Oquist Landscape Design, dated August 4, 2020, included in Appendix A. These plans involve removal of the existing block walls on the property and construction of several block walls up to 4 feet tall. The plans also specify installation of new pavers, decorative aggregate, artificial turf, natural sod, and planting beds. The amount of new impervious surface has been maximized to meet the City’s guidelines of 65 percent of the total property area. Based on our review of the City code, the project can be completed on the slope provided a geotechnical report is prepared and adequate engineering supporting the improvements are provided. In addition to the improvement plans on the property, restoration of the HOA parcel will be completed. This will involve removal of the existing stairs and block walls, regrading of the area, and planting of appropriate vegetation. SITE EXPLORATION Our field study included drilling four exploration borings using limited-access equipment (Figure 3). The various types of sediments, as well as the depths where the characteristics of the sediments changed, are indicated on the exploration logs presented in Appendix B. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types. If changes occurred between sample intervals in our explorations, they were interpreted. Our explorations were approximately located in the field by measuring from known site features depicted on the topographic survey. The conclusions and recommendations presented in this letter-report are based, in part, on the explorations completed for this study. The numbers, locations, and depths of the explorations were completed within site and budgetary constraints. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this letter-report and make appropriate changes. DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Hirani Residence Retaining Wall Renton, Washington Geotechnical Engineering Report December 1, 2020 ASSOCIATED EARTH SCIENCES, INC. JG/ms - 20190438E001-3 Page 3 Exploration Borings The exploration borings for this study (EB-1 through EB-4) were completed by advancing a 6.5-inch, outside-diameter, hollow-stem auger using a subcontracted portable Acker drill. During the drilling process, samples were generally obtained at 2½- to 5-foot depth intervals. The borings were continuously observed and logged by an engineering geologist from our firm. The exploration logs presented in Appendix B are based on the field logs, drilling action, and observation of the samples collected. Locations of the explorations are presented on Figure 3, “Site and Exploration Plan.” Disturbed but representative samples were obtained by using the Standard Penetration Test (SPT) procedure in accordance with ASTM International (ASTM) D-1586. This test and sampling method consists of driving a standard 2-inch, outside-diameter, split-barrel sampler a distance of 18 inches into the soil with a 140-pound hammer free-falling a distance of 30 inches. The number of blows for each 6-inch interval is recorded, and the number of blows required to drive the sampler the final 12 inches is known as the Standard Penetration Resistance (“N”) or blow count. If a total of 50 is recorded within one 6-inch interval, the blow count is recorded as the number of blows for the corresponding number of inches of penetration. The resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive soils; these values are plotted on the attached exploration boring logs. The samples obtained from the split-barrel sampler were classified in the field and representative portions placed in watertight containers. The samples were then transported to our laboratory for further visual classification. SUBSURFACE CONDITIONS Subsurface conditions on the project site were inferred from the field explorations conducted for this study, visual reconnaissance of the site, and a review of applicable geologic literature. As shown on the field logs, a general sequence of soils encountered at the site consisted of fill, recessional outwash, and glacial till. The native deposits we encountered at the site are in general agreement with mapped geologic conditions presented on the regional geologic map (Geologic Map of King County, Washington, Booth, Troost, and Wisher, GeoMap NW, March 2007) indicates that the area is underlain by Vashon recessional outwash and glacial till. Our interpretation of the sediments encountered in our explorations agrees with the above geologic map. The following section presents more detailed subsurface information on the sediment types encountered at the site. DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Hirani Residence Retaining Wall Renton, Washington Geotechnical Engineering Report December 1, 2020 ASSOCIATED EARTH SCIENCES, INC. JG/ms - 20190438E001-3 Page 4 Stratigraphy Fill Fill soils (those not naturally placed) were encountered in all the borings to depths ranging from 2 to 7 feet. The fill encountered generally consisted of loose to very loose, moist to very moist, brown to brownish gray, fine to coarse sand with trace to some silt, trace gravel, and trace organics. The fill is generally suitable for reuse as structural fill during summer earthwork activities with moisture conditioning as needed to achieve suitable moisture content for compaction purposes. The fill is not suitable for foundation support of new retaining walls in its current loose to very loose condition. Vashon Recessional Outwash Exploration borings EB-1 through EB-3 encountered loose to medium dense, moist, brown to grayish brown, fine to coarse sand with trace silt and trace gravel interpreted as Vashon recessional outwash. Where encountered, the recessional outwash was observed in our explorations below the fill. Recessional outwash was deposited from meltwater streams from the retreating glacier of the most recent regional glaciation. Recessional outwash is generally suitable for support of light to moderately loaded foundations and is expected to be suitable for use in structural fill applications during summer earthwork activities with moisture conditioning as needed to achieve suitable moisture content for compaction purposes. Vashon Lodgement Till Exploration borings EB-2 through EB-4 encountered very dense, moist, gray, silty, fine sand with trace to some gravel interpreted as Vashon lodgement till. Where encountered, the lodgement till was observed in our explorations below the recessional outwash and extended beyond the maximum depth explored. Lodgement till was deposited at the base of an active ice sheet and was subsequently compacted by the weight of the overlying glacial ice. Lodgement till typically possesses high-strength and low-compressibility attributes. Hydrology Groundwater was not observed in our exploration borings completed for this project at the time of drilling in January 2020. However, it should be noted that perched groundwater seepage may occur during the winter and spring months. Perched groundwater occurs when surface water infiltrates down through relatively permeable soils such as the lodgement till and becomes trapped or “perched” atop a comparatively impermeable barrier. This infiltration can occur at great distances from the area where the groundwater is encountered. It should be noted that fluctuations in the level of the groundwater may occur due to the time of year and DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Hirani Residence Retaining Wall Renton, Washington Geotechnical Engineering Report December 1, 2020 ASSOCIATED EARTH SCIENCES, INC. JG/ms - 20190438E001-3 Page 5 variations in the amount of rainfall. The quantity and duration of flow from excavations made into the perched zone will vary depending on season, topography, and soil grain size. Laboratory Testing Two samples of surficial native soils were selected for laboratory testing. Grain-size analysis results are presented in Appendix B. SLOPE HAZARDS AND MITIGATION Prior to construction of the current tiered block wall, the project area was characterized by steeply sloping areas that were associated with original grading of the backyard of the lot. Review of lidar-based topography prior to construction of the current walls indicates slopes inclined at about 67 percent which would be classified as high landslide hazard areas under the current City of Renton Municipal Code (RMC) Section 4-3-050 due to a slope inclination greater than 40 percent. Construction of engineered retaining walls will reduce the potential for future slope failures and landslide hazard risk. Global Stability An analysis of the static and seismic global stability with the proposed tiered wall was conducted using the computer program SLOPE/W 2007, version 8.16 by GEOSLOPE International. The program used the Morgenstern–Price method for evaluating a rotational failure. Input parameters for the analysis included slope geometry, geology, soil strength parameters, and seismic conditions. For evaluation of slope stability under seismic conditions, a horizontal ground acceleration of 0.27g was used for our analysis; this value is equivalent to half of the peak horizontal ground acceleration. Soil strength parameters used for our analysis were assumed based on typical published values for similar materials and our prior experience. The values assumed for our analysis are shown on the SLOPE/W profiles included in Appendix C. The slope geometry used for our analysis was based on a topographic survey of the property. Cross-Section A-A’ shown on Figure 2 was selected for our analysis. The stability of a slope can be expressed in terms of its factor of safety. The factor of safety is the ratio between the forces that resist sliding to the forces that drive sliding. For example, a factor of safety of 1.0 would indicate a slope where the driving forces and the resisting forces are exactly equal. Increasing factor of safety values greater than 1.0 indicate increased stability. Factors of safety below 1.0 indicate conditions where the driving forces exceed resisting forces. In accordance with standard of practice, the minimum factors of safety are 1.5 for static conditions and 1.1 for dynamic (seismic) conditions. Minimum factors of safety of DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Hirani Residence Retaining Wall Renton, Washington Geotechnical Engineering Report December 1, 2020 ASSOCIATED EARTH SCIENCES, INC. JG/ms - 20190438E001-3 Page 6 about 1.9 and 1.13 under static and seismic conditions, respectively, were calculated for deep-seated failure surfaces for the slope area with a tiered retaining wall in place. EROSION HAZARDS AND MITIGATIONS Based on our review of the United States Department of Agriculture (USDA) National Resource Conservation Survey (NRCS) website, geologic mapping, and our site explorations, the site is underlain primarily by recessional outwash and lodgement till as described previously in this letter-report. The USDA NRCS website classifies these soils as a moderate risk of erosion when present on slopes of 15 to 30 percent. Based on the USDA NRCS classification and RMC Section 4-3-050, the sloping areas in the backyard prior to construction of the current tiered walls would meet the classification as a low erosion hazard area given the soil conditions. Project plans should include implementation of temporary erosion controls in accordance with local standards of practice. Control methods should include limiting earthwork to seasonally drier periods, typically April 1 to October 31, use of perimeter silt fences, and straw mulch in exposed areas. Removal of existing vegetation should be limited to those areas that are required to construct the project, and new landscaping and vegetation with equivalent erosion mitigation potential should be established as soon as possible after grading is complete. During construction, surface water should be collected as close as possible to the source to minimize silt entrainment that could require treatment or detention prior to discharge. Timely implementation of permanent drainage control measures should also be a part of the project plans and will help reduce erosion and generation of silty surface water onsite. CONCLUSIONS AND RECOMMENDATIONS In our opinion, the planned improvements are feasible from a geotechnical standpoint. Based on the explorations advanced for this study, we encountered a significant thickness of very loose to loose granular fill below the existing block walls. In our opinion, the existing segmental block walls need to be removed and replaced with properly engineered walls. New segmental block gravity walls can be constructed using the existing PisaLite blocks and no-fines concrete (NFC) backfill provided the PisaLite blocks are not damaged. NFC is similar to permeable concrete except that it has approximately half the compressive strength. The existing fill generally contains a low percentage of silt and is suitable for reuse as structural fill. In order to achieve adequate global static and seismic factors of safety it will be necessary to overexcavate the loose soils below the bottom of the lower wall tier and replace them with controlled density fill (CDF). DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Hirani Residence Retaining Wall Renton, Washington Geotechnical Engineering Report December 1, 2020 ASSOCIATED EARTH SCIENCES, INC. JG/ms - 20190438E001-3 Page 7 Segmental Block Wall Design AESI designed the planned segmental gravity block walls based on our review of current plans and available subsurface information. We designed the segmental block walls using the computer software program Vespa2 Version 2.10.7.7359. For seismic design we used a ground acceleration of 0.27g (50 percent of peak ground acceleration [PGA]). Our analysis indicates that that wall tiers with an exposed height of 4 feet can be constructed with a 2-foot-wide zone of NFC. Calculations supporting the design of the retaining walls are included in Appendix D, and wall details are presented on construction plan sheet Figure G-1. Site Preparation Site preparation will be needed in areas for the new walls and the adjacent sloping parcel owned by the HOA where regrading and replanting will be necessary. In areas for new walls, we recommend removal of all organic debris, if present, and any other deleterious material. Areas where looser native soils exist should be recompacted in place. Or, if this is not feasible due to either soil composition or moisture content, the loose soils should be removed and replaced as subsequently recommended for structural fill placement. As mentioned previously, we recommend overexcavation and replacement of the loose soils below the base of the lower wall tier with CDF. Based on our subsurface explorations, we anticipate overexcavation of about 6½ feet will be necessary below the wall base. In the sloping area, we recommend that any existing loose surficial soil resulting from disturbance associated with removal of stairs and walls be compacted to a firm and non-yielding condition. Once the existing stairs and block wall portions are removed, the adjacent sloping parcel owned by the HOA will require some limited regrading and revegetation. We recommend that permanent slopes be graded to a maximum inclination of 2H:1V (Horizontal:Vertical), if possible, or to the previous slope inclination. Loose surficial soils should be compacted to a firm and non-yielding condition with portable compaction equipment. We recommend a geosynthetic erosion control fabric or jute mat be used on the slope until vegetation becomes established. We recommend that the slope be revegetated with appropriate native plantings. In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction. For estimating purposes, we anticipate that temporary, unsupported, near-vertical cut slopes having a maximum height of 3 to 4 feet could be made in the recessional outwash for new wall construction. Temporary cut slopes greater than 4 feet should inclined at a maximum of 1.5H:1V. As is typical with earthwork operations, some sloughing and raveling may occur, especially if groundwater seepage is present in the excavation cuts. As a result, cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA regulations should be followed at all times. DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Hirani Residence Retaining Wall Renton, Washington Geotechnical Engineering Report December 1, 2020 ASSOCIATED EARTH SCIENCES, INC. JG/ms - 20190438E001-3 Page 8 Based on our observations, the on-site soils have a low to moderate percentage of fine-grained material making them slightly to moderately moisture-sensitive and subject to disturbance when wet. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs, the softened soils should be removed, and the area brought to grade with structural fill. Any exposed soils should also be protected with plastic sheeting during the winter months. Structural Fill All fill placed beneath or behind new segmental block walls or as part of a regraded slope shall be considered structural fill. All references to structural fill in this letter-report refer to subgrade preparation, fill type and placement, and compaction of materials, as discussed in this section. If a percentage of compaction is specified under another section of this letter-report, the value given in that section should be used. Any existing site soils containing organics or debris should be stripped from all areas to receive structural fill. The existing grade should then be compacted to a firm and non-yielding condition. After recompaction of the exposed ground is approved, structural fill may be placed as required to attain desired grades. Structural fill is defined as non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts, with each lift being compacted to at least 95 percent of the modified Proctor maximum density using ASTM D-1557 as the standard. Soils in which the amount of fine-grained material (smaller than the No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered moisture-sensitive. Use of moisture-sensitive soil in structural fills should be limited to favorable dry weather conditions. The fill and recessional outwash contain low to moderate amounts of silt and are considered slightly to moderately moisture-sensitive. Based on the field moisture contents, the near-surface native soils appear to be near optimum moisture content for compaction. If structural fill is to be placed during wet weather and proper compaction cannot be obtained with the on-site soils, a select material consisting of a clean, free-draining gravel and/or sand should be used. Free-draining fill consists of non-organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction. DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Hirani Residence Retaining Wall Renton, Washington Geotechnical Engineering Report December 1, 2020 ASSOCIATED EARTH SCIENCES, INC. JG/ms - 20190438E001-3 Page 9 A representative from AESI should observe the stripped subgrade and be present during placement of structural fill to observe the work and perform a representative number of in-place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses and problem areas may be corrected at that time. Wall Drainage It is imperative that proper drainage be provided so that hydrostatic pressures do not develop against segmental block walls. As part of the wall design, a 24-inch-wide NFC zone will be used as wall backfill which will also serve as wall drainage. A drainpipe consisting of rigid, perforated, polyvinyl chloride (PVC) pipe will be included at the base of the NFC. The wall drains should be constructed with sufficient gradient to allow gravity discharge to a suitable discharge location. Due to the presence of a moderately thin layer of recessional outwash overlying glacial till, it is our opinion that a drywell is not feasible to collect water from the wall drains without possible off-site impacts. Permanent Erosion Control As part of the project, we understand that exposed soil surfaces will be covered with pavers, artificial turf, natural sod, and decorative gravel. On the slope above the existing rockery wall, we understand that artificial turf will be used. Vendor information provided to us suggests that various products allow for drainage through the turf into the underlying soils as opposed to forming a relatively impervious barrier. We collected surface soil samples at two locations on the slope above the existing rockery along the northern side of the property for laboratory testing. Our grain-size analyses results indicate the soils are composed of sand with some gravel and silt to silty sand with some gravel. We estimate that these silty soils have a low to moderate ability to infiltrate surface water runoff. CONSTRUCTION MONITORING We recommend that AESI provide geotechnical monitoring during construction of the new segmental block walls to verify conformance with our design as follows: • Verify the wall base bears on suitable subgrade soils and leveling pad. • Verify placement of blocks is in accordance with the plans. • Verify placement of NFC wall backfill. • Verify installation of proper wall drainage. DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 MERCER ISLAND NEWCASTLE RENTON Copyright:© 2013 National Geographic Society, i-cubed King CountyBurnettAveN N 27th PlLa keWashing t onBlv dN± NOTE: BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION VICINITY MAP PROJ NO. DATE: FIGURE:\\kirkfile2\GIS\GIS_Projects\aaY2019\190438 Hirani Res Retaining Wall\aprx_mxd\20190438E001 F1 VM_Hirani.aprx!( ¥ ¥ ¥405 ¬«169 ¬« ¬« ¬« SITE 120190438E0011/20 0 20001000 FEET DATA SOURCES / REFERENCES: USGS: 7.5' SERIES TOPOGRAPHIC MAPS, ESRI/I-CUBED/NGS 2013 KING CO: STREETS, CITY LIMITS 1/19, PARCELS 4/19 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE HIRANI RESIDENCE RETAINING WALL RENTON, WASHINGTON DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 W illiamsAveNN 27th Pl 130 120 110 100 90 80 100908060 5070 Pictometry, King County PROJ NO. NOTE: BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION DATE:FIGURE: ±G:\GIS_Projects\aaY2019\190438 Hirani Res Retaining Wall\aprx_mxd\20190438E001 F2 ESM_Hirani.aprxDATA SOURCES / REFERENCES: PSLC: KING COUNTY 2016, GRID CELL SIZE IS 3'. DELIVERY 1 FLOWN 2/24/16 - 3/28/16 CONTOURS FROM LIDAR KING CO: STREETS, 1/19, PARCELS 4/19 AERIAL: PICTOMETRY INT. 2017 LOCATIONS AND DISTANCES SHOWN ARE APPROXIMATE 0 50 Feet EXISTING SITE AND EXPLORATION PLAN HIRANI RESIDENCE RETAINING WALL RENTON, WASHINGTON 20190438E001 1/20 2 Pierce County King County SITE PARCEL CONTOUR 10 FT CONTOUR 2 FT DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 NOTES: 1. BASE MAP REFERENCE: TOUMA ENGINEERS AND LAND SURVEYORS, PLLC, 2708 WILLIAMS AVE N, SURVEY WORKSHEET 12/2019, SIGNED 2/4/20.190438 Hirani \ 20190438 E001 F3 S-E w-site .cdrHIRANI RESIDENCE RENTON, WASHINGTON SITE AND EXPLORATION PLAN PROJ NO.DATE:FIGURE: 20190438E001 11/20 3 BLACK AND WHITE REPRODUCTION OF THIS COLOR ORIGINAL MAY REDUCE ITS EFFECTIVENESS AND LEAD TO INCORRECT INTERPRETATION. a s s o c i a t e d e a r t h s c i e n c e s i n c o r p o r a t e d FEET 10 200 N CONTOUR INTERVAL = 2’ LEGEND: EXPLORATION BORING SOIL SURFACE SAMPLE EB NOTE: LOCATION AND DISTANCES SHOWN ARE APPROXIMATE. SS A’ASS-1 SS-2 EB-3 EB-1 EB-2 EB-4 APPROXIMATE EXTENT OF SLOPE ON HOA PROPERTY TO BE REGRADED AND REVEGETATED EXISTING WALLS AND STAIRS TO BE REMOVED - BLOCKS TO BE REUSED - TYP DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 EXIST I N G S L O P E MIN 4" DIAMETER PERFORATED RIGID PVC PIPE - PROVIDE MIN 1% CONTINUOUS SLOPE TO APPROVED OUTLET - TYP FIRM UNDISTURBED SOIL OR STRUCTURAL FILL MUST BE VERIFIED BY GEOTECHNICAL ENGINEER PRIOR TO PLACEMENT OF LEVELING PAD 2' TYP 12" MINEMBEDTYPEXISTING BLOCK WALLREMOVE AND REUSE6"HX12"X12" BLOCKSEXISTING BLOCK WALLREMOVE AND REUSE6"HX12"X12" BLOCKSEXISTING ROCKERYTO REMAINEXISTING ROCKERYTO REMAINTOW = 118 WALL HEIGHT (H)5' MAXEL = ~118 TOW = 114 WALL HEIGHT (H)5' MAXBOW = 109 EL = ~110 LEVEL LEVEL LEVEL 6" MIN LOW PERMEABILITY SOIL - TYP FALL PROTECTION BY OTHERS IF REQUIRED - TYP 6' MIN EXCAVATION LIMITS SHALL BE IN ACCORDANCE WITH WISHA/OSHA REGULATIONS AND RECOMMENDATIONS OF GEOTECHNICAL REPORT NO-FINES CONCRETE TYP RETAINED SOIL REUSE BLOCK TYP REUSE CAP TYP BOW = 113 CONTROLLED DENSITY FILL~6.5' FIELD VERIFY3' MIN 6" MIN CRUSHED ROCK LEVELING PAD SLEEVE-IT 1224R 12"Ø x 24" SET IMMEDIATELY BEHIND TOPMOST BLOCK UNIT FILL SLEEVE WITH CONCRETE AND SET FENCE POST CAP UNIT BLOCK UNIT TYP STEEL FENCE OR RAILING T O W = 1 1 4 B O W = 1 0 9 TOW = 118BOW = 113AA'EXISTING WALLS AND STAIRS TO BE REMOVED - BLOCKS TO BE REUSED - TYP NEW BLOCK W A L L NEW BLOCK W A L L APPROXIMATE EXTENT OF SLOPE ON HOA PROPERTY TO BE REGRADED AND REVEGETATED CROSS-SECTION A - A' NO SCALE DRAWN BY: DATE PROJECT NO. F I G U R E CHECKED BY:i n c o r p o r a t e de a r t h s c i e n c e sa s s o c i a t e d911 Fifth AvenueKirkland, WA 98033(425) 827-77011552 Commerce Street, Suite 102Tacoma, WA 98402(253) 722-2992508 S. Second Street, Suite 101Mount Vernon, WA 98273(425) 827-7701aesgeo.comaesgeo.comaesgeo.comPISALITE BLOCK WALLHIRANI RESIDENCERENTON, WASHINGTONEIN SAS 11/20 20190438E001 G1190438 Hirani \ 190438 Wall Pisa.dwg LAYOUT: E001 G1 Wall PisaSITE PLAN AND WALL LAYOUT REFERENCE: TOUMA ENGINEERS AND LAND SURVEYORS, PLLC, 2708 WILLIAMS AVE N, SURVEY WORKSHEET, 12/19, SIGNED 2/4/20 DESIGN NOTES: DESIGN OF THE SEGMENTAL RETAINING WALL IS BASED ON THE FOLLOWING VALUES: INTERNAL ANGLE OF FRICTION FOR RETAINED SOIL = 34 DEGREES UNIT WEIGHT OF SOIL = 125 LB/CU FT MAXIMUM EXPOSED WALL HEIGHT = 5' MAX BATTER OF WALL = 7° BACKFILL SLOPE = LEVEL EMBEDMENT = 12" MIN 1. SRW UNITS SHALL BE PISALITE. 2. CONTRACTOR TO VERIFY ALL LOCATIONS, ELEVATIONS, AND DIMENSIONS. 3. SUBGRADE PREPARATION, DRAINAGE PROVISIONS, AND OTHER RELEVANT SOIL CONSIDERATIONS SHALL BE IN ACCORDANCE WITH THE PROJECT GEOTECHNICAL REPORT. GENERAL NOTES: WORK SHALL CONSIST OF CONSTRUCTION OF A PISALITE BLOCK RETAINING WALL SYSTEM IN ACCORDANCE WITH THESE SPECIFICATIONS AND IN REASONABLY CLOSE CONFORMITY WITH THE LINES, GRADES, DESIGN, AND DIMENSIONS SHOWN ON THESE PLANS. PISALITE BLOCKS SHALL BE LAID IN A RUNNING BOND STANDARD PATTERN PER MANUFACTURERS SPECIFICATIONS. NO ALTERNATE WALL SYSTEMS WILL BE CONSIDERED. SEGMENTAL RETAINING WALL (SRW) UNITS 1. SRW UNITS SHALL BE MACHINE-FORMED CONCRETE BLOCKS SPECIFICALLY DESIGNED FOR RETAINING WALL APPLICATIONS. 2. PISALITE UNITS SHALL CONFORM TO THE FOLLOWING ARCHITECTURAL REQUIREMENTS: A. FACE COLOR - AS SPECIFIED BY THE OWNER. B. FACE FINISH - FORM LINER FACE FINISH IN A NATURAL STONE APPEARANCE AND TEXTURE. OTHER FACE FINISHES WILL NOT BE ALLOWED WITHOUT WRITTEN APPROVAL OF OWNER. C. BOND CONFIGURATION - RUNNING WITH BONDS NOMINALLY LOCATED AT MIDPOINT VERTICALLY ADJACENT UNITS. D. EXPOSED SURFACES OF UNITS SHALL BE FREE OF CHIPS, CRACKS OR OTHER IMPERFECTIONS WHEN VIEWED FROM A DISTANCE OF 10 FEET (3 M) UNDER DIFFUSED LIGHTING. 3. PISALITE BLOCK CONCRETE MATERIALS SHALL CONFORM TO THE REQUIREMENTS OF ASTM C1372, STANDARD SPECIFICATIONS FOR SEGMENTAL RETAINING WALL UNITS. 4. PISALITE BLOCK UNITS SHALL CONFORM TO THE FOLLOWING STRUCTURAL AND GEOMETRIC REQUIREMENTS MEASURED IN ACCORDANCE WITH APPROPRIATE REFERENCES: A. COMPRESSIVE STRENGTH: 3000 PSI (21 MPA) PER ASTM C1372. B. ABSORPTION: 7.5 LBS/FT³ FOR STANDARD WEIGHT AGGREGATES C. UNIT SIZE / WEIGHT (LBS): PISALITE BLOCK : 6" H X 12" D X 12" L / 44 LBS PISALITE CAP: 3-1/8"" H X 13" D X 24" L / 73 LBS LEVELING PAD / FILL MATERIAL 1. MATERIAL FOR LEVELING PAD SHALL CONSIST OF COMPACTED GRAVEL OR UNREINFORCED CONCRETE AND SHALL BE A MINIMUM OF 6 INCHES IN DEPTH. 2. FILL FOR UNITS SHALL BE NO-FINES CONCRETE. NO-FINES CONCRETE BACKFILL 1. NO-FINES CONCRETE IS A COMBINATION OF COARSE AGGREGATE, CEMENT, AND WATER. THE CEMENT SHALL COMPLY WITH THE REQUIREMENTS FOR USE IN READY-MIX CONCRETE (ASTM C94). THE TYPICAL CEMENT CONTENT IN NO-FINES CONCRETE SHOULD RANGE BETWEEN 350 LB/YD³ - 500 LB/YD³. THE WATER TO CEMENT RATIO FOR NO-FINES CONCRETE SHOULD RANGE BETWEEN 0.3 - 0.5. 2. COARSE AGGREGATE MUST MEET THE REQUIREMENTS FOR CONCRETE AGGREGATES (ASTM C33). AGGREGATE SIZES WILL RANGE BETWEEN 3/8-INCHES TO 3/4-INCHES (9.5MM TO 19MM) AGGREGATE WITH AN AGGREGATE/CEMENT RATIO OF 5.5:1 TO 6.5:1. 3. NO-FINES PRODUCT DENSITY WILL RANGE DEPENDING ON THE MIX DESIGN. TYPICAL UNIT WEIGHT WILL RANGE BETWEEN 100 LB/FT³ TO 135 LB/FT³. 4. NO-FINES CONCRETE VOID CONTENT SHALL RANGE BETWEEN 18% - 35% (ASTM C140). LEVELING PAD CONSTRUCTION 1. LEVELING PAD SHALL BE PLACED AS SHOWN ON THE CONSTRUCTION DETAILS WITH A MINIMUM THICKNESS OF 6 INCHES. 2. FOUNDATION SOIL SHALL BE COMPACTED TO A FIRM AND NON-YIELDING CONDITION. OVEREXCAVATION (OR OTHER METHODS) AT THE DIRECTION OF THE GEOTECHNICAL ENGINEER MAY BE REQUIRED TO PROVIDE A SUITABLE BASE FOR LEVELING PAD CONSTRUCTION. OVEREXCAVATED AREAS SHALL BE BACKFILLED WITH AN APPROVED STRUCTURAL FILL COMPACTED TO 95% OF THE MODIFIED PROCTOR. 3. LEVELING PAD MATERIAL SHALL BE COMPACTED TO PROVIDE A LEVEL HARD SURFACE ON WHICH TO PLACE THE FIRST COURSE OF UNITS. COMPACTION WILL BE BY MECHANICAL PLATE COMPACTORS TO 95% OF MODIFIED PROCTOR DENSITY. 4. LEVELING PAD SHALL BE PREPARED TO PROVIDE INTIMATE CONTACT OF RETAINING WALL UNIT WITH PAD. SEGMENTAL UNIT INSTALLATION 1. FIRST COURSE OF SRW UNITS SHALL BE PLACED ON THE LEVELING PAD. THE UNITS SHALL BE CHECKED FOR LEVEL AND ALIGNMENT. THE FIRST COURSE IS THE MOST IMPORTANT TO ENSURE ACCURATE AND ACCEPTABLE RESULTS. 2. ENSURE THAT UNITS ARE IN FULL CONTACT WITH BASE. 3. UNITS ARE PLACED SIDE BY SIDE FOR FULL LENGTH OF STRAIGHT WALL ALIGNMENT. ALIGNMENT MAY BE DONE BY MEANS OF A STRING LINE OR OFFSET FROM BASE LINE TO A MOLDED FINISHED FACE OF THE SRW UNIT. 4. INSTALL NEXT COURSE OF WALL UNITS ON TOP OF BASE COURSE. POSITION BLOCKS TO BE OFFSET FROM SEAMS OF BLOCKS BELOW. PERFECT 'RUNNING BOND' IS NOT ESSENTIAL, BUT A 3 INCH (75MM) MINIMUM OFFSET IS RECOMMENDED. CHECK EACH BLOCK FOR PROPER ALIGNMENT AND LEVEL. 5. FILL THE VOIDS OF THE BLOCK AND BACKFILL TO THE DESIGNATED DEPTH WITH NO-FINES CONCRETE BACKFILL. THE VERTICAL HEIGHT OF A POUR SHOULD NOT EXCEED 16 INCHES (406 MM) OR TWO COURSES OF BLOCK. 6. THE NO-FINES CONCRETE BACKFILL SHALL BE PLACED AND COMPACTED AS SOON AS POSSIBLE AFTER MIXING AS IT TENDS TO DRY OUT RAPIDLY BECAUSE OF ITS OPEN STRUCTURE. COMPACTION IS ACHIEVED BY RODDING THE CONCRETE; VIBRATION MUST NOT BE USED AND HEAVY TAMPING IS NOT NECESSARY. 7. BRUSH THE TOP OF THE BLOCKS TO REMOVE ANY EXCESS MATERIAL. IT IS RECOMMENDED THAT THIS BE DONE BEFORE ALLOWING THE CONCRETE TO HARDEN. 8. INSTALL ADDITIONAL COURSES OF WALL UNITS. POSITION BLOCKS TO BE OFFSET FROM SEAMS OF BLOCKS BELOW. PERFECT 'RUNNING BOND' IS NOT ESSENTIAL, BUT A 3 INCH (75MM) MINIMUM OFFSET IS RECOMMENDED. CHECK EACH BLOCK FOR PROPER ALIGNMENT AND LEVEL. 9. ADDITIONAL NO-FINES CONCRETE BACKFILL POURS CAN BE MADE AS SOON AS THE NO-FINES CONCRETE BACKFILL IN THE PREVIOUS LIFT HAS SET, WHICH IS USUALLY NOT LONGER THAN 2 TO 3 HOURS. ONCE THE BACKFILL HAS SET, PLACE THE NO-FINES CONCRETE BACKFILL IN THE CORES AND TO THE DESIGNED DEPTH AS PER WALL LAYOUT. 10. INSTALL EACH SUBSEQUENT COURSE IN LIKE MANNER. REPEAT PROCEDURE TO THE EXTENT OF WALL HEIGHT 11. UPPERMOST ROW OF SRW OR CAPS SHALL BE GLUED TO UNDERLYING UNITS WITH AN ADHESIVE, AS RECOMMENDED BY THE MANUFACTURER. INSPECTIONS 1. INSPECTION OF THE WALL CONSTRUCTION, INCLUDING FOUNDATION SOIL, LEVELING PAD CONSTRUCTION, DRAINAGE, AND NO-FINES CONCRETE, SHALL BE COMPLETED BY THE GEOTECHNICAL ENGINEER. 2. CALL BEFORE YOU DIG: CALL 811 TO LOCATE UTILITIES AT LEAST 72 HOURS (3 BUSINESS DAYS) PRIOR TO BEGINNING EXCAVATION. MANUFACTURER'S UNIT SIZING NO SCALE FENCE SECTION AND PLAN DETAIL IF REQUIRED NO SCALE DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 APPENDIX A Conceptual Plan by Oquist Landscape Design DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Scale : Date : Property Owner : Contact # : Site Address : Drawing Number : Drawing Description : 1/8" = 1' 8/4/2020 Rick, Hirani 425.830.2387 2708 Williams Ave North Renton WA 98056 Concept Drawing Update 5 1 of 1 Designer Signature : 425.979.1933 Artificial Turf Decorative Aggregate Planting Bed Sod Block Retaining Wall Seat Wall (20" Sitting Height) Paver Patio Or Landing Existing Deck Existing Rock Retaining Wall Existing Concrete Step or Wall Light GENERAL DRAWING NOTES: All measurements, heights, and dimensions given are subject to verification by installing contractor and property owner. Every attempt to insure the accuracy of this drawing has been made by Oquist Landscape Design. However, all parties should be aware that minor changes may be needed once construction begins for the proper completion of this design. Neither Concept Drawings or Builders Drawings should be considered binding plans or agreements between a contractor or property owner. Any and all permits required for the completion of this design are the responsibility of the property owner, and or licensed contractor(s). 20'-0" 6'-0"3'-0"4 '- 0 " 8 '- 0 " 11'-0" 4'-0" 9 '- 0 " 12'-0" 4 '- 0 " 4 '- 0 " 4'-0" This Area to Restore back to Native Prop. Line Prop. Line French Drain Seat Wall 20" WALL 1 : Up to 4'-0" WALL 2 : Up to 4'-0" WALL 3 : 1'-0" WALL 4 : 4'-0" WALL 5 : 4'-0" WALL 6 : Up to 4'-0" 4'-0" 12'-0" 1 2 '- 0 " 4'-0" Existing Rockery to Remain as is Existing Rockery to Remain as is DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 APPENDIX B Exploration Logs and Grain-Size Distributions DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 1 1 2 1 1 2 1 1 6 5 8 9 5 8 11 7 50/5" Bottom of exploration boring at 14 feet due to refusal. No groundwater encountered. Fill Moist to very moist, brown, fine to medium SAND, some silt to silty, trace fine organics (SP-SM). Moist, grayish brown, fine to medium SAND, trace silt, trace gravel; occasional clasts of dark brown silty sand with trace organics; massive (SP). Vashon Recessional Outwash Moist, grayish brown, fine to medium SAND, trace silt, trace gravel; massive (SP). Grades to fine to medium sand (SP). Grades to fine to coarse sand, some gravel; broken gravel fragments in sampler tip (SP). S-1 S-2 S-3 S-4 S-5 S-6 1 of 1 NAVD 88 JG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 6.25 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 20190438E001 1/8/2020,1/8/2020 Logged by: Shelby Tube Sample 140# / 30 CN Drilling / HSA Well~120 5 10 15 EB-1 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Hirani Residence Retaining Wall M - Moisture AESIBOR 20190438E001.GPJ January 21, 202033 33 77 1717 1919 5050/5" DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 1 0 1 1 1 1 1 0 1 2 3 3 1 32 50/4" 50/6" Bottom of exploration boring at 13 feet due to refusal. No groundwater encountered. Fill Moist, brownish gray, fine to coarse SAND, trace gravel, trace silt; occasional clasts of dark brown, silty, sand with trace organics; massive (SP). Vashon Recessional Outwash Moist, brownish gray, fine to coarse SAND, trace gravel, trace silt; massive (SP). Upper 8 inches: as above; very moist (SP). Vashon Lodgement Till Lower 8 inches: moist, gray, silty, fine SAND, trace gravel; unsorted (SM). S-1 S-2 S-3 S-4 S-5 S-6 1 of 1 NAVD 88 JG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 6.25 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 20190438E001 1/8/2020,1/8/2020 Logged by: Shelby Tube Sample 140# / 30 CN Drilling / HSA Well~120 5 10 15 EB-2 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Hirani Residence Retaining Wall M - Moisture AESIBOR 20190438E001.GPJ January 21, 202011 22 11 66 5050/4" 5050/6" DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 2 3 8 7 10 9 1 4 5 11 20 21 13 24 25 50/4" Bottom of exploration boring at 14 feet due to refusal. No groundwater encountered. Fill Moist, brown, fine to medium SAND, trace to some silt, trace gravel; occasional clasts of dark brown, silty, sand, trace organics; massive (SP-SM). No recovery. Vashon Recessional Outwash Moist, brown, fine to medium SAND, trace silt, trace gravel; massive (SP). Upper 9 inches: as above; very moist. Vashon Lodgement Till Lower 9 inches: moist, gray, silty, fine SAND, some gravel; unsorted (SM). S-1 S-2 S-3 S-4 S-5 S-6 1 of 1 NAVD 88 JG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 6.25 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 20190438E001 1/8/2020,1/8/2020 Logged by: Shelby Tube Sample 140# / 30 CN Drilling / HSA Well~120 5 10 15 EB-3 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Hirani Residence Retaining Wall M - Moisture AESIBOR 20190438E001.GPJ January 21, 20201111 1919 99 4141 4949 5050/4" DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 2 5 7 33 28 24 50/6" Bottom of exploration boring at 6.5 feet due to refusal. No groundwater encountered. Fill Very moist, brown, fine to coarse SAND, trace gravel, trace silt; massive (SP). Vashon Lodgement Till Moist, gray, silty, fine SAND, trace gravel; unsorted (SM). Difficult drilling 2 to 5 feet. Adding water. S-1 S-2 S-3 1 of 1 NAVD 88 JG2" OD Split Spoon Sampler (SPT) 3" OD Split Spoon Sampler (D & M)Water LevelProject Name JHSWater Level ()Approved by: 30 Blows/Foot Samples Ground Surface Elevation (ft) Grab SampleSymbol 6.25 40 Datum Hammer Weight/Drop Sampler Type (ST): S T Project Number 20 Renton, WA Date Start/Finish CompletionLocation Sheet Depth (ft)Exploration Number 20190438E001 1/8/2020,1/8/2020 Logged by: Shelby Tube Sample 140# / 30 CN Drilling / HSA Well~120 5 10 15 EB-4 Ring Sample No RecoveryGraphic 10 Other TestsHole Diameter (in) DESCRIPTION Driller/Equipment Blows/6"Exploration Boring Water Level at time of drilling (ATD) Hirani Residence Retaining Wall M - Moisture AESIBOR 20190438E001.GPJ January 21, 20201212 52 5050/6" DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 6.8 6.2 78.1 2.4 6.56 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite - Top of Rockery #1 Client: Project: Project No:Figure SAND some gravel some silt 3/4" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 97.1 93.2 88.6 87.0 14.3 8.9 7.3 6.9 6.5 6.3 NP NV NP SP-SM A-1-b 3.1648 1.8902 1.3797 1.2547 1.0348 0.8604 0.5177 2.67 1.50 1/15/20 1/21/20 MS ss 1/15/20 Shezan Hirani Hirani Residence Retaining Wall 20190438 E001 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Particle Size Distribution Report PERCENT FINER0 10 20 30 40 50 60 70 80 90 100 GRAIN SIZE - mm. 0.0010.010.1110100 % +3"Coarse % Gravel Fine Coarse Medium % Sand Fine Silt % Fines Clay 0.0 0.0 10.7 7.1 54.8 14.6 12.86 in.3 in.2 in.1½ in.1 in.¾ in.½ in.3/8 in.#4#10#20#30#40#60#100#140#200TEST RESULTS Opening Percent Spec.*Pass? Size Finer (Percent)(X=Fail) Material Description Atterberg Limits (ASTM D 4318) Classification Coefficients Date Received:Date Tested: Tested By: Checked By: Title: Date Sampled:Location: Onsite - Top of Rockery #2 Client: Project: Project No:Figure Silty SAND some gravel 3/4" 3/8" #4 #8 #10 #20 #40 #60 #100 #200 #270 100.0 93.7 89.3 84.0 82.2 43.4 27.4 20.0 15.7 12.8 11.9 NP NV NP SM A-1-b 5.3173 2.6902 1.1821 0.9797 0.5052 0.1320 1/15/20 1/21/20 MS SS 1/15/20 Shezan Hirani Hirani Residence Retaining Wall 20190438 E001 PL=LL=PI= USCS (D 2487)=AASHTO (M 145)= D90=D85=D60= D50=D30=D15= D10=Cu=Cc= Remarks *(no specification provided) DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 APPENDIX C Global Stability Results DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 1.120Distance (Ft.)0 102030405060708090100Elevation (Ft.)708090100110120130Color Name Unit Weight(pcf)Cohesion'(psf)Phi' (°)CDF 115 3,000 25Old Fill 120 0 31Structural Fill 125 50 38Vashon Lodgement Till125 150 38Vashon Recessional Outwash120 0 36Wall/No Fines Concrete125Hirani Residence Retaining Wall201900438E001Seismic ConditionDocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 1.877Distance (Ft.)0 102030405060708090100Elevation (Ft.)708090100110120130Color Name Unit Weight(pcf)Cohesion'(psf)Phi' (°)CDF 115 3,000 25Old Fill 120 0 31Structural Fill 125 50 38Vashon Lodgement Till125 150 38Vashon Recessional Outwash120 0 36Wall/No Fines Concrete125Hirani Residence Retaining Wall201900438E001Static ConditionDocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 APPENDIX D Wall Calculations DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Project: Hirani Retaining Wall Site: Renton Date: 10/15/2020 Wall: 4 foot block wall DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Project: - Hirani Retaining Wall [Rev. 1] Renton Wall: 4 foot block wall Project Design Inputs Design Standard National Concrete Masonry Association 3rd Edition Minimum Factors of Safety Conventional External Value Internal Value Facing Value FSsl Base Sliding 1.50 FSsl Internal Sliding 1.50 FSbc Bearing Capacity 2.00 FSsc Shear Capacity 1.50 FSot Overturning 1.50 MultiDepth External Value Internal Value Facing Value FSsl Base Sliding 1.50 FSbc Bearing Capacity 2.00 FSot Overturning 1.50 No Fines External Value Internal Value Facing Value FSsl Base Sliding 1.50 FSbc Bearing Capacity 2.00 FSot Overturning 1.50 Reinforced External Value Internal Value Facing Value FSsl Base Sliding 1.50 FSsl Internal Sliding 1.50 FScs Connection Strength 1.50 FSbc Bearing Capacity 2.00 FSpo Pullout 1.50 FSsc Facing Shear 1.50 FSct Crest Toppling 1.50 FSto Tensile Overstress 1.50 FSot Overturning 2.00 Seismic Conventional External Value Internal Value Facing Value FSsl Base Sliding 1.10 FSsl Internal Sliding 1.10 FSbc Bearing Capacity 1.10 FSsc Shear Capacity 1.10 FSot Overturning 1.10 MultiDepth External Value Internal Value Facing Value FSsl Base Sliding 1.10 FSbc Bearing Capacity 1.10 FSot Overturning 1.10 No Fines External Value Internal Value Facing Value FSsl Base Sliding 1.10 FSbc Bearing Capacity 1.50 FSot Overturning 1.10 Reinforced External Value Internal Value Facing Value FSsl Base Sliding 1.10 FSsl Internal Sliding 1.10 FScs Connection Strength 1.10 FSbc Bearing Capacity 1.50 FSpo Pullout 1.10 FSsc Facing Shear 1.10 FSct Crest Toppling 1.10 FSto Tensile Overstress 1.10 FSot Overturning 1.50 Design Factors Term Description (as appl.) Minimum (as appl.) Maximum RC Reinforced coverage ratio 1.00 0.00 Selected Facing Unit Licensor/Product Line: Risi Stone Systems Name: PisaLite Page 2 Printed 10/15/2020 Version: 2.10.7.7359 Powered by Vespa DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Project: - Hirani Retaining Wall [Rev. 1] Renton Wall: 4 foot block wall Facing Height Hu 0.49 ft Facing Width Lu 0.66 ft Facing Depth Wu 0.98 ft Facing Weight Xu 97 lb/ft³ Center of Gravity Gu 0.49 ft Setback Δu 0.06 ft Batter ω 7.12 ° Cap Height Hcu 0.25 ft Initial Shear Capacity au 938.75 lb/ft Apparent Shear Angle λu 57.00 ° Maximum Shear Capacity Vu(max)6098.44 lb/ft Selected Reinforcement Types Reinforcements 5XT - Mirafi Miragrid 5XT Supplier: TenCate Geosynthetics - Mirafi, Fill Type: Sands Tult 4,700.00 lb/ft RFcr 1.44 RFd 1.10 LTDS 2,825.88 lb/ft RFid 1.05 Cds 0.80 Ci 0.80 Connection/Shear Properties αcs1 548.17 lb/ft IP-1 3,097.18 lb/ft αcs2 2,336.59 lb/ft IP-2 3,097.87 lb/ft αcs max 2,336.59 lb/ft au 938.75 lb/ft λu 57.00 lb/ft Vu(max)6,098.44 lb/ft Selected Soil Types Soil Zone Soil Type Angle φ Friction [lb/ft³] Density γ In Situ [lb/ft²] Cohesion Cf Infill (i)SM 34°125.02 n/a Retained (r)SM 34°125.02 n/a Foundation (f)SM 34°125.02 0.00 Base (b)GW 39°140.02 n/a Drainage (d)GP 38°125.02 n/a Soil Glossary CH:Inorganic clays, high plasticity CL:Inorganic clays, low to medium plasticity, gravelly, sandy, silty, lean clays GC:Clayey gravels, poorly graded gravel-sand-clay mixtures GM:Silty gravels, poorly graded gravel-sand-silt mixtures GP:1/2"-3/4" clean crushed stone or crushed gravel GW:Well-graded gravels, gravel-sand. Little or no fines. MH:Inorganic clayey silts, elastic silts ML:Inorganic silts, very fine sands, silty or clayey, slight plasticty SC:Clayey sands, poorly graded sand-clay mixtures SM:Silty sands, poorly graded sand-silt mixtures SP:Poorly-graded sands, gravelly sands. Little or no fines. SW:Well-graded sands, gravelly sands. Little or no fines. Page 3 Printed 10/15/2020 Version: 2.10.7.7359 Powered by Vespa DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Project: - Hirani Retaining Wall [Rev. 1] Renton Wall: 4 foot block wall Analysis Summary Lowest Values - No Fines Static Analysis Test Description Section Course Requirement Minimum Result Status FSsl Base Sliding 1 1.50 4.22 Pass FSbc Bearing Capacity 1 2.00 18.81 Pass FSot Overturning 1 1.50 7.19 Pass No Fines Depth Min. No Fines Depth 1 1.0000 2.0000 Pass No Fines L/H RatioMin. No Fines L/H Ratio 1 0.4000 0.6064 Pass Seismic Analysis Test Description Section Course Requirement Minimum Result Status FSsl Base Sliding 1 1.10 1.31 Pass FSbc Bearing Capacity 1 1.50 9.40 Pass FSot Overturning 1 1.10 2.07 Pass Below Standard Values None Page 4 Printed 10/15/2020 Version: 2.10.7.7359 Powered by Vespa DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Project: - Hirani Retaining Wall [Rev. 1] Renton Wall: 4 foot block wall Section 1 Details Section 1 Cross-section Section 1 Cross-section Details Upper Slope Angle β 0.00 ° Crest Offset 0.00 ft Live Load ql 0 lb/ft² Live Offset qlofs 0.00 ft Dead Load qd 0 lb/ft² Dead Offset qdofs 0.00 ft Peak Acceleration As 0.52 Top of Section 4.25 ft Bottom Grade 0.00 ft Base of Section -0.92 ft Design Height H 4.92 ft Embedment Depth Hemb 0.92 ft * Analysis includes Vertical Forces * Embedment is included in Bearing Capacity Empirical Checks Check Description Min. Requirement Result Status Hemb Minimum Embedment %10.0000 23.0300 Pass MinHemb Minimum Embedment 6.0000 11.0551 Pass No Fines Depth Min. No Fines Depth 1.0000 2.0000 Pass No Fines L/H Ratio Min. No Fines L/H Ratio 0.4000 0.6064 Pass External Checks Static Check Description Min. Requirement Result Status FSbc Bearing Capacity 2.00 18.81 Pass FSct Crest Toppling 1.50 74.14 Pass FSot Overturning 1.50 7.19 Pass FSsl Base Sliding 1.50 4.22 Pass Seismic FSbc Bearing Capacity 1.50 9.40 Pass FSot Overturning 1.10 2.07 Pass FSsl Base Sliding 1.10 1.31 Pass Page 5 Printed 10/15/2020 Version: 2.10.7.7359 Powered by Vespa DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Project: - Hirani Retaining Wall [Rev. 1] Renton Wall: 4 foot block wall Static Calculations General Equations Width of rein. layer for internal sliding L"s 0.00 ft Eq. 7-8 Slope for internal analysis βint 0.00 °Eq. 7-46 Increase in height due to backslope hs 0.00 ft Eq. 7-7 Horizontal width of rein. zone at backslope Lβ 2.00 ft Eq. 7-11 Aggregate Extension of Lβ L11 0.00 ft Eq. 7-4 Height of Wall impacted by live load Hgl 4.92 ft Eq. No Fines Height of Wall impacted by dead load Hgd 4.92 ft Eq. No Fines Height of back of wall for ext. stability Hext 4.92 ft Eq. 7-10 Load from Live Load Surcharge WLFL 0.00 lb/ft Eq. No Fines Load from Dead Load Surcharge WDLF 0.00 lb/ft Eq. No Fines Weight from Slope - Part "A"WβA 0.00 lb/ft Eq. 7-31A1 Weight from Slope - Part "B"WβB 0.00 lb/ft Eq. 7-31A2 Weight from Slope - Part "C"WβC 0.00 lb/ft Eq. 7-31A3 Weight from Slope - Part "D"WβD 0.00 lb/ft Eq. 7-31B Interface friction angle δc 34.00 °Eq. 6-2 Maximum height of slope influence hmaxcon 0.00 ft Eq. 6-4 Average slope within influence area βcon 0.00 °Eq. 6-5 External active earth pressure Kaext 0.207 Eq. 7-1 External live load reduction factor qlfactor 1.000 Eq. External dead load reduction factor qdfactor 1.000 Eq. Active earth force due to soil weight Ps 313.90 lb/ft Eq. 6-6 Horz. active earth force due to soil weight PsH 279.98 lb/ft Eq. 6-9 Horz. active earth force due to dead load PqdH 0.00 lb/ft Eq. 6-11 Horz. active earth force due to live load PqlH 0.00 lb/ft Eq. 6-12 Total horz. active earth force PaH 279.98 lb/ft Eq. 6-13 Vert. active earth force due to soil weight PsV 141.92 lb/ft Eq. 6-14 Vert. active earth force due to dead load PqdV 0.00 lb/ft Eq. 6-15 Vert. active earth force due to live load PqlV 0.00 lb/ft Eq. 6-16 Total vert. active earth force PaV 141.92 lb/ft Eq. 6-17 Moment arm for WβA XwβA 1.60 ft Eq. 7-36A1 Moment arm for WβB XwβB 2.60 ft Eq. 7-36A2 Moment arm for WβC XwβC 3.60 ft Eq. 7-36A3 Moment arm for WβD XwβD 2.93 ft Eq. 7-36B Resisting moment arm for PsH Ys 1.64 ft Eq. 7-18 Resisting moment arm for PqH Yq 2.46 ft Eq. 7-19 Base Sliding Masonry friction reduction factor μ 0.700 Eq. Ref.25 Base sliding resistance Rs 1182.89 lb/ft Eq. 6-19 Base sliding FSsl 4.225 Eq. 6-20 Overturning Resisting moment arm for rein. zone Xri 1.77 ft Eq. 7-35 Resisting moment Mr 3303.46 lb Eq. 7-34 Driving moment Mo 459.29 lb Eq. 7-38 Overturning FSot 7.193 Eq. 7-39 Bearing Capacity Bearing pressure Qac 587.66 lb/ft²Eq. 6-27 Equivalent bearing area B 2.98 ft Eq. 7-40 Eccentricity of bearing force e 0.00 ft Eq. 7-41 Ultimate bearing capacity Qult 11051.09 lb/ft²Eq. 12-1 Bearing capacity FSbc 18.805 Eq. 12-6 Seismic Calculations General Equations Seismic inertial angle θint 25.81 °Eq. 9-3,4 Internal horz. acceleration coefficient khint 0.484 Eq. 9-22,23 External horz. acceleration coefficient khext 0.275 Eq. 9-24,25 External seismic inertial angle θext 15.36 °Eq. 9-27 Seismic active earth pressure coefficient KaEext 0.432 Eq. 9-48 Seismic active earth pressure coefficient KaEint 0.714 Eq. 9-81 Horz. component of earth pressure coefficient KaEH 0.385 Eq. 9-28 Horz. component of dynamic coefficient ΔKDynH 0.200 Eq. 9-29 Horz. total earth force ΔPDynH 302.94 lb/ft Eq. 9-31 Page 6 Printed 10/15/2020 Version: 2.10.7.7359 Powered by Vespa DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 Project: - Hirani Retaining Wall [Rev. 1] Renton Wall: 4 foot block wall Horz. dynamic earth force increment PaEH 431.45 lb/ft Eq. 9-32 Vert. component of earth pressure coefficient KaEV 0.195 Eq. 9-33 Vert. component of dynamic coefficient ΔKDynV 0.101 Eq. 9-34 Vert. dynamic earth force increment PaEV 295.48 lb/ft Eq. 9-35 Vert. total earth force ΔPDynV 153.56 lb/ft Eq. 9-36 Weight of reduced width reinforced mass W'i 835.55 lb/ft Eq. 9-61 Reduced width reinforced zone L"0.5H 0.00 ft Eq. 9-62 Reduced height reinforced zone h'0.00 ft Eq. 9-63 Weight of top slope for reduced rein. mass W'β 0.00 lb/ft Eq. 9-64,69 Weight of top slope for reduced rein. mass W'β2 0.00 lb/ft Eq. 9-65 Horz. inertial force PIR 358.75 lb/ft Eq. 9-60 YβA YβA 4.92 ft Eq. No Fines YβC YβC 4.92 ft Eq. No Fines Y'β Y'β 4.92 ft Eq. No Fines Y'βB Y'βB 4.92 ft Eq. No Fines M'β M'β 0.00 lb/ft Eq. No Fines hir hir 2.46 ft Eq. No Fines Base Sliding Seismic sliding resistance Rscdyn 1037.61 lb/ft Eq. 9-37 Base sliding FSsl 1.313 Eq. 9-38 Overturning Resisting moment Mr 3556.19 lb Eq. 9-39 Driving moment Mo 1714.75 lb Eq. 9-40 Seismic overturning FSot 2.074 Eq. 9-41 Bearing Capacity Ultimate bearing pressure Qult 8555.31 lb/ft²Eq. 12-10 Applied bearing pressure Qa 909.81 lb/ft²Eq. 9-42 Applied bearing stress at leveling pad B'c 2.01 ft Eq. 9-43 Eccentricity of bearing force e 0.49 ft Eq. 9-44 Bearing pressure FSbc 9.403 Eq. 9-44X Page 7 Printed 10/15/2020 Version: 2.10.7.7359 Powered by Vespa DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 ATTACHMENT D DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1 DocuSign Envelope ID: 7942E970-BC7D-44A2-AC45-6F38C47154A1