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HomeMy WebLinkAboutPN_Project_Narrative_220715_v1SOUND TRANSIT • Union Station 401 S. Jackson St., Seattle, WA 98104-2826 • Reception: (206) 398-5000 • FAX: (206) 398-5499 www.soundtransit.org July 15, 2022 Clark H. Close Senior Planner Jonathan Chavez Civil Engineer III City of Renton 1055 S. Grady Way Renton, WA 98057 SUBJECT: South Renton Transit Center Site Remediation: Temporary Use Permit, Building Grading Permit and Critical Areas Approval Site address: 750 Rainier Ave S, Renton, WA 98057 Dear Clark and Jonathan, Sound Transit is proposing to conduct soil remediation work and allow temporary artwork (“project”) at 750 Rainier Avenue S in Renton, the South Renton Transit Center site, to address known contaminated materials (Figure 1 and Figure 2) and facilitate an opportunity discussed by City and Sound Transit leadership in July 2022 for temporary artwork at the currently vacant site. The soil remediation work will require excavating and removing soils on site and backfilling with non-contaminated soil. Allowing installation of temporary artwork at the site is not anticipated to require any site improvements. Per discussions with Renton staff, this work requires a Temporary Use Permit and a Building Grading Permit from the City of Renton. The South Renton Transit Center site is completely located within Renton’s Seismic Hazard Area (Figure 4) and a Wellhead Protection Area, Zone 2 (Figure 5). Per Renton Municipal Code (RMC) 4-3-050C.3, the proposed site remediation work is not an exempt activity in a Seismic Hazard Area or a Wellhead Protection Area. Therefore, as part of the Temporary Use Permit and Building Grading Permit Sound Transit is also requesting a Critical Area review and approval. As part of the permit application materials, Sound Transit is submitting this project narrative and figures to: provide a project description of the proposed site remediation work and temporary artwork; address the Temporary Use Permit decision criteria in RMC Section 4-9-240J; and address Renton’s critical area regulations. ZONING DESIGNATION AND CURRENT SITE USE The South Renton Transit Center site, located at 750 Rainier Avenue S, is in a highly developed commercial area (northeast of the intersection of Rainier Avenue S (State Route (SR) 167) and S Grady Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation SOUND TRANSIT • Union Station 401 S. Jackson St., Seattle, WA 98104-2826 • Reception: (206) 398-5000 • FAX: (206) 398-5499 www.soundtransit.org Way). See the Neighborhood Detail Map in Figure 3. The South Renton Transit Center site, and the surrounding area, is zoned Commercial Arterial (CA). Sound Transit owns the four parcels that comprise the site (King County parcel numbers 192305 - 9035, 9063, 9068, 9074); the prior businesses on the site have been relocated. In September 2021, the City of Renton approved a demolition permit, a critical areas exemption (for work within a Seismic Hazard Area) and a critical areas approval (for work within a Wellhead Protection Area) for the demolition and removal of the four buildings that were on-site. Demolition of these four buildings was completed on January 14, 2022; the building foundations remain. SPECIAL SITE FEATURES The South Renton Transit Center site is completely located within Renton’s Seismic Hazard Area (Figure 4) and a Wellhead Protection Area, Zone 2 (Figure 5). No other critical areas, such as wetlands, streams, or steep slopes, are present on the site. Included with these application materials is the Critical Areas Assessment of the South Renton Transit Center and Roadway Improvements project component that was prepared for the I-405 BRT Project. SOIL TYPE AND DRAINAGE CONDITIONS The soils on the site are alluvium consisting of sand and gravel deposited by the Cedar River. Subsurface testing at the South Renton Transit Center site found loose fill soils over alluvial soils primarily comprised of soft silts and loose sands. Recent geotechnical borings conducted at the site indicate that liquefiable soils are present; denser soils were encountered below soils that are subject to liquefaction. This site is in the Green River subwatershed within WRIA 9: Duwamish – Green. Runoff from the site is currently collected and conveyed to a storm system within Rainier Avenue S. This system crosses Rainier Avenue S north of S Grady Way and conveys flow to Springbrook Creek. Runoff from S Grady Way is collected and conveyed south to Rolling Hills Creek through privately owned parcels south of S Grady Way. Rainier Avenue S has two drainage basins. North of S Grady Way, runoff from Rainier Avenue S is directed to Springbrook Creek and south of S Grady Way runoff is directed to Rolling Hills Creek. PROJECT DESCRIPTION Environmental site assessments conducted in 2017 and 2018 identified contaminated soils on the South Renton Transit Center site. Additional soil testing conducted in July 2021 further identified the extent of contaminated areas on the site. Five areas of contamination have been identified on-site, as shown in the Remediation Plan Drawing in Figure 1 and Figure 2. Areas 1, 2 and 3 are in the north, central portion of the site. Area 4 is located to the southwest of Areas 1 through 3, toward Rainier Avenue S. Area 5 is in the southeast portion of the site adjacent to the right-of-way for S Grady Way. Based on the areas contaminated and the types of contaminants a plan has been developed to remediate the site. The project is generally described below and shown in the drawings in Figure 1 and Figure 2. Sound Transit’s general contractor will determine the full means and methods for the project. The project does not include work off the South Renton Transit Center site and does not include removing trees or work within close proximity to an existing tree on-site; the nearest existing tree on- site is along S Grady Way approximately 150 feet west of Area 5. Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation SOUND TRANSIT • Union Station 401 S. Jackson St., Seattle, WA 98104-2826 • Reception: (206) 398-5000 • FAX: (206) 398-5499 www.soundtransit.org In addition to the soil remediation described above, City and Sound Transit leadership in July 2022 have identified an opportunity for future use of the South Renton Transit Center site, on a temporary basis ahead of South Renton Transit Center construction, to include installation of temporary artwork at the currently vacant site. The temporary artwork would generally be located where there is greatest visibility, such as the perimeter of the site. Dewatering In Areas 1, 3, 4 and 5 dewatering would be required as needed to complete excavation. Groundwater may be encountered up to a depth of 7 feet below ground surface. The dewatering system would be designed to treat the removed water on-site. No dewatering would be required for Area 2. Excavation and Backfill In each area the existing ground surface, of either reinforced concrete or asphalt pavement, would be removed. As excavation occurs in each area the slopes, or sides, would be reinforced to maintain a safe work area. Based on field observations, excavated soil will be segregated into: suspected non- contaminated/geotechnically suitable soil and suspected non-contaminated/not suitable soil. The remaining contaminated soil removed, approximately 75 percent, will be transported off-site and disposed of at a Subtitle D Facility. Table 1 shows the volume of soils that are anticipated to be excavated in Areas 1, 3, 4 and 5. The volume of fill in each area is anticipated to be similar or the same (estimated to be placed 2,148 cubic yards). All excavated areas would be backfilled with non- contaminated suitable fill material and compacted. Backfill materials are specified on the Remediation Plan Drawing, and the contract specifications require that all backfill materials not specified are to be Gravel Borrow conforming to Washington State Department of Transportation (WSDOT) Standard Specifications, Section 9-03.14. Following the excavation and backfill of Areas 1, 3, 4, 5, the surface will be restored with 2 inches of compacted asphalt. Table 1. Volume of Displaced Soil by Area Location Displaced Soil (cubic yards) Area 1 1,733 Area 3 119 Area 4 119 Area 5 178 TOTAL 2,148 Other than removing the existing ground surface, no additional soils will be removed in Area 2. In Area 2, two inches of asphalt will be placed over areas where the existing ground surface was removed. The following provides additional information for the work proposed in each area. Area 1 Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation SOUND TRANSIT • Union Station 401 S. Jackson St., Seattle, WA 98104-2826 • Reception: (206) 398-5000 • FAX: (206) 398-5499 www.soundtransit.org This area of remediation is approximately 65 feet by 60 feet and will be excavated to a depth of approximately 12 feet. In this area, it is anticipated that utilities (such as electrical, sanitary sewer, and fiber optic lines) would be encountered as shown in the plan. During excavation these lines will be cut- and-capped or removed. During backfill and compaction, the bottom 4 feet of soil is to first be mixed with biostimulation material. Area 2 – In-Situ Remediation Area 2 is approximately 60 feet by 60 feet. Prior to beginning injections potholing will occur to establish the alignment of a waterline in this area. The grid of well points will be adjusted to avoid this waterline. The existing slab foundation or ground surface would be removed at the injection point/hole locations. The biostimulation material will be injected uniformly in each hole to a depth of between 11 feet and 20 feet below the ground surface. After injections, the well points will be surfaced with 2 inches of asphalt. Area 3 and 4 Both Areas 3 and 4 are approximately 20 feet by 20 feet in size and will be excavated to a depth of approximately 8 feet and then backfilled with suitable fill material. Area 5 Area 5 is approximately 20 feet by 12 feet and will be excavated to a depth of approximately 8 feet and then backfilled with suitable fill material. Temporary Artwork Based on discussions between City and Sound Transit leadership in July 2022, following the remediation of contaminated soils, Sound Transit would install temporary artwork. It is understood that no pavement, landscaping, lighting, or other improvements are generally needed to accommodate installation of the temporary artwork. Use of the site for temporary artwork would cease when construction activity for the South Renton Transit Center commences, unless otherwise agreed upon by the City and Sound Transit. TEMPORARY USE PERMIT APPROVAL RMC Section 4-9-240J lists Renton’s decision criteria to approve a Temporary Use Permit. Table 2 provides an evaluation for how the project complies with the decision criteria. Additional information on the project’s construction activities and methods is provided in the Construction Mitigation Description included with this application package. Table 2. Project Compliance with RMC 4-9-240J – Temporary Use Permit Decision Criteria Temporary Use Permit Decision Criteria Evaluation of Project Compliance 1. The temporary use will not be materially detrimental to the public health, safety, or welfare, nor injurious to property or improvements in the vicinity of the temporary use The project will clean up known contaminated soils on the site, which will have a long-term benefit to public health and prevent contamination from the site migrating to adjacent properties. Sound Transit has conducted environmental site assessments of the site to identify the areas of Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation SOUND TRANSIT • Union Station 401 S. Jackson St., Seattle, WA 98104-2826 • Reception: (206) 398-5000 • FAX: (206) 398-5499 www.soundtransit.org Temporary Use Permit Decision Criteria Evaluation of Project Compliance contamination and the types of contaminants. Based on this information the project has been developed with methods to ensure the safety of construction workers, appropriate measures to treat groundwater on-site, and the safe handling and removal of contaminated materials. The areas will be backfilled with clean soils and the surface will be restored with 2 inches of compacted asphalt. The project will also have a short-term benefit to public health, safety, and welfare by providing temporary artwork at the currently vacant site, prior to construction of the South Renton Transit Center. As part of the Temporary Use Permit application materials, Sound Transit has submitted a construction mitigation description and hazardous materials management statement, and will be providing a drainage memorandum and a Temporary Erosion and Sediment Control (TESC) plan, for the City of Renton’s review and approval. Sound Transit understands that Renton will not issue the Temporary Use Permit and the Building Grading Permit until all of these items have been approved. 2. Adequate parking facilities and vehicle ingress and egress are provided to serve the temporary use and any existing uses on the site All project activities, including worker parking and construction staging, will occur on the site. The site still includes the surface parking areas that were developed to support the automobile sales and repair use, prior to the relocation of those businesses. The existing driveways into the site from Rainier Avenue S and S Grady Way will provide adequate ingress and egress. Both Rainier Avenue S and S Grady Way are City of Renton designated haul routes for trucks over 26,000 pounds gross vehicle weight and provide nearby and quick access to and from SR 167 and I-405. 3. Hours of operation of the temporary use are specified, and would not adversely impact surrounding uses The hours of operation of the temporary use will comply with Renton’s code requirements and will not adversely impact surrounding uses. The project will adhere to the City of Renton’s regulations to control construction noise, which restricts non-residential construction noise on weekdays to the hours of 7:00 a.m. to 8:00 p.m., on Saturdays to the hours of 9:00 a.m. to 8:00 p.m., and prohibits construction noise on Sundays. If an unanticipated reason arises, and construction activities are required at night or on Sundays, Sound Transit would apply for a construction noise variance. Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation SOUND TRANSIT • Union Station 401 S. Jackson St., Seattle, WA 98104-2826 • Reception: (206) 398-5000 • FAX: (206) 398-5499 www.soundtransit.org Temporary Use Permit Decision Criteria Evaluation of Project Compliance 4. The temporary use will not cause nuisance factors such as noise, light, or glare which adversely impact surrounding uses The project would not cause a noise, light or glare impact that would adversely impact the surrounding uses. As noted above, the project will adhere to the City of Renton’s regulations to control construction noise. In addition, to reduce construction noise the project will use construction equipment with engine exhaust silencers and engine-casing sound insulation and would minimize the use of generators. Project work will occur during daylight hours and nighttime lighting of the site will not be required. Standard construction equipment will be used, which will not result in glare that would adversely impact surrounding uses. Candidate temporary artwork will be coordinated with the City of Renton to ensure that no nuisance noise, light, or glare will result. 5. If applicable, the applicant has obtained the required right-of-way use permit The project does not require a right-of-way use permit. CRITICAL AREAS APPROVAL As previously noted, the entire South Renton Transit Center site is in a Seismic Hazard Area and a Wellhead Protection Area, Zone 2, as designated and mapped by the City of Renton. Therefore, all of the proposed remediation activities are located within these critical areas. No other critical areas or associated buffers are located on the site. Prior to any development or alteration of a property containing a critical area, RMC 4-3-050.C.1 notes that the owner or designee must obtain a development permit, critical area permit, and/or letter of exemption. Seismic Hazard Area Per RMC 4-3-050.C.3, grading and site remediation activities are not exempt activities permitted within Geologic Hazard Areas, which include Seismic Hazard Areas. Within Geologically Hazardous Areas RMC 4-3-050D.5 provides the City of Renton’s Administrator with the authority to review proposed activities and issue a critical areas permit for proposed activities. RMC 4-3-050J.1 provides the criteria for modifying a geologically hazardous area, which includes submitting an independently reviewed geotechnical report. A geotechnical report for the site is being submitted as part of the Temporary Use Permit and Building Grading Permit submittal materials. As shown in the Topography Map (Figure 6) the South Renton Transit Center site is very flat. The proposed grading and site remediation activities would not create an unstable slope on the site or on adjacent properties. The site is within a Seismic Hazard Area, which would require additional structural Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation SOUND TRANSIT • Union Station 401 S. Jackson St., Seattle, WA 98104-2826 • Reception: (206) 398-5000 • FAX: (206) 398-5499 www.soundtransit.org considerations in the design of buildings to ensure their safety and stability during an earthquake event. The project does not include the construction of a structure or building. Therefore, the proposed project activities comply with the requirements of the Seismic Hazard Area. Wellhead Protection Area, Zone 2 Within Wellhead Protection Areas, grading is not an exempt activity. Per RMC 4-3-050C.3.i, for hazardous materials there is an exemption if cleanups are done under supervision of the Washington Department of Ecology or U.S. Environmental Protection Agency. This exemption does not apply to this South Renton Transit Center site remediation work. RMC 4-3-050D.5 provides the City of Renton’s Administrator with the authority to review and inspect uses and activities within Wellhead Protection Areas. RMC 4-3-050D.4.c notes that within Wellhead Protection Areas “no changes in land use shall be allowed nor shall permits for development be issued if the Department finds that the proposed land use, activity, or business is likely to impact the long-term, short- term or cumulative quality of the aquifer.” In the vicinity of the South Renton Transit Center site, the depth from the surface of the ground to the water table varies. Overall, the City of Renton has identified that the shallowest points of the Cedar Valley Aquifer is 23 feet below ground surface (bgs) (https://www.rentonwa.gov/city_hall/public_works/utility_systems/water_utility_engineering/water_c onservation/aquifer_protection). The drinking water wells located in the Downtown Renton wellfield were installed up to a depth of approximately 100 feet bgs. In Area 1 the estimated depth of excavation is 12 feet and in Areas 3, 4 and 5 the estimated depth of excavation is 8 feet. Therefore, the depth of the proposed excavation is not anticipated to disturb groundwater in the aquifer or create a path for contaminants to migrate into the aquifer. The proposed site remediation activities will not impact the long-term, short-term or cumulative quality of the aquifer. The purpose of the project is to remove and remediate the contamination on the site, which would help to improve the quality of the aquifer over time. Several site investigations have been conducted to identify the types of contaminants on the site and to identify the area and depth where they are located. The project’s proposed site remediation will address the identified contamination and minimize future potential effects to human health and the environment from exposure and migration, including minimizing the potential for future interactions with the Cedar Valley Sole Source Aquifer. As noted in the above project description, during grading activities an on-site dewatering system would be designed to treat the removed groundwater on-site. The project would not place contaminated groundwater into Renton’s sewer or storm drain system. In addition, as soils are excavated contaminated soils will be segregated from non-contaminated soils and will be transported off-site and disposed of at a facility approved to handle such materials. In compliance with the requirements of RMC 4-3-050G.8 the project would not require the storage or use of hazardous materials. Therefore, the project would not degrade groundwater quality and would conform with the intent of the Wellhead Protection Area, Zone 2. Critical Areas Conclusion In conclusion, the proposed South Renton Transit Center site remediation is in compliance with the City of Renton’s Critical Area Development Standards in RMC 4-3-050.G. Further, the purpose of the project Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation SOUND TRANSIT • Union Station 401 S. Jackson St., Seattle, WA 98104-2826 • Reception: (206) 398-5000 • FAX: (206) 398-5499 www.soundtransit.org is to cleanup existing known contamination on the South Renton Transit Center site which would have benefit the long-term condition of the Cedar Valley Aquifer. Therefore, per RMC 4-3-050D.5a.i Sound Transit requests the City of Renton issue a Critical Areas Approval along with the Temporary Use Permit and Building Grading Permit. Please feel free to contact me at 206-903-7071 or Gary.Yao@soundtransit.org if you have any questions or need additional information in regards to the Temporary Use Permit, Building Grading Permit or Critical Areas Approval. Thank you for your time in processing this request. Sincerely, Gary Yao Senior Current Planner Sound Transit Enc: Figure 1: South Renton Transit Center Site Remediation Plan Drawing (Sheet 1) Figure 2: South Renton Transit Center Site Remediation Plan Drawing (Sheet 2) Figure 3: South Renton Transit Center Site Neighborhood Detail Map Figure 4: South Renton Transit Center Site Remediation - Seismic Hazard Area Figure 5: South Renton Transit Center Site Remediation - Wellhead Protection Area Figure 6: South Renton Transit Center Site Remediation - Topography Map Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation 9 Figure 1. South Renton Transit Center Remediation Plan Drawing (Sheet 1) Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation SOUND TRANSIT • Union Station 401 S. Jackson St., Seattle, WA 98104-2826 • Reception: (206) 398-5000 • FAX: (206) 398-5499 www.soundtransit.org Figure 2. South Renton Transit Center Remediation Plan Drawing (Sheet 2) Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation SOUND TRANSIT • Union Station 401 S. Jackson St., Seattle, WA 98104-2826 • Reception: (206) 398-5000 • FAX: (206) 398-5499 www.soundtransit.org Figure 3. South Renton Transit Center Site – Neighborhood Detail Map Temporary Use Permit, Building Grading Permit and Critical Areas Approval: South Renton Transit Center Site Remediation 12 Figure 4. South Renton Transit Center Site Remediation - Renton Seismic Hazard Area Figure 5. South Renton Transit Center Site Remediation - Renton Wellhead Protection Area Figure 6. South Renton Transit Center Site Remediation – Topography Map Note: Buildings shown in black outline on the USGS topography map have been demolished. Only the building foundations currently remain.