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HomeMy WebLinkAboutC_NW3233-SouthEndAutoSite_NFAOpinionLetter_20250314.pdfSTATE OF WASHINGTON DEPARTMENT OF ECOLOGY Northwest Region Office PO Box 330316, Shoreline, WA 98133-9716 • 206-594-0000 March 14, 2025 Dale Walker D+C Investments, LLC 3400 East Valley Road Renton WA 98057 (dwalker@walkersrenton.com) Re: No Further Action opinion for the following contaminated Site Site name: South End Auto Site address: 3400 E Valley Rd, Renton WA 98057 Facility/Site ID: 27793456 Cleanup Site ID: 14715 VCP Project No.: NW3233 Dear Dale Walker: The Washington State Department of Ecology (Ecology) received your request for an opinion regarding the sufficiency of your independent cleanup of the South End Auto facility (Site) under the Voluntary Cleanup Program (VCP).1 To provide an opinion, we requested additional information from you in writing on December 30, 2024. We received the additional information on January 28, 2025. This letter provides our opinion and analysis. We are providing this opinion under the authority of the Model Toxics Control Act (MTCA), Chapter 70A.305 RCW.2 Opinion Ecology has determined that no further remedial action is necessary to clean up contamination at the Site. Ecology bases this opinion on an analysis of whether the remedial action meets the substantive requirements of MTCA and its implementing regulations, which are specified in Chapter 70A.305 RCW and Chapter 173-340 WAC3 (collectively called “MTCA”). 1 https://ecology.wa.gov/Spills-Cleanup/Contamination-cleanup/Voluntary-Cleanup-Program 2 https://app.leg.wa.gov/RCW/default.aspx?cite=70A.305 3 https://apps.leg.wa.gov/WAC/default.aspx?cite=173-340 Electronic Copy Dale Walker March 14, 2025 Page 2 Site Description This opinion applies only to the Site described below. The Site is defined by the nature and extent of contamination associated with the following releases: • Total petroleum hydrocarbons in the gasoline, diesel and oil ranges (TPH-G, TPH-D, and TPH- O); benzene, toluene, ethylbenzene, and xylenes (BTEX); cadmium; chromium; arsenic; lead; zinc; nickel; polychlorinated biphenyls (PCBs); polycyclic aromatic hydrocarbons (PAHs); tetrachloroethene (PCE); trichloroethene (TCE); and 2-butanone (MEK), and acetone into soil; • TPH-G, TPH-D, TPH-O, benzene, toluene, PAHs, vinyl chloride, barium, cadmium, chromium, arsenic, nickel, zinc, and lead into groundwater; and • Air-phase hydrocarbons, methane, benzene, naphthalene, 1,3-butadiene, chloroform, and acrolein into soil vapor. Enclosure A includes a Site description, history, and diagrams. Please note that releases from multiple sites can affect a parcel of real property. Soil samples collected from three locations adjacent to the eastern Site boundary contained TPH concentrations above MTCA Method A cleanup levels. These locations are upgradient of Site contamination sources (areas formerly used for vehicle salvage activities) and are approximately 35 feet from the paved shoulder of southbound State Route (SR) 167. This soil contamination is likely associated with SR 167, which is not a contaminated site listed by Ecology. See Enclosure A below for further discussion. The parcel of real property associated with this Site is also located within the projected boundaries of the Tacoma Smelter King County facility (Facility Site ID 66948686). Currently, Ecology has no information indicating that contamination from the Tacoma Smelter King County facility affects this parcel. This opinion does not apply to any contamination associated with the Tacoma Smelter King County facility. Basis for the Opinion Ecology bases this opinion on information in the documents listed in Enclosure B. You can request these documents by filing a records request.4 For help making a request, contact the Public Records Officer at recordsofficer@ecy.wa.gov or call (360) 407-6040. Before making a request, check if the documents are available on the Site webpage 5. This opinion is void if information in any of the listed documents is materially false or misleading. Analysis of the Cleanup Ecology has concluded that no further remedial action is necessary to clean up contamination at the Site. Ecology bases its conclusion on the following analysis: 4 https://ecology.wa.gov/About-us/Accountability-transparency/Public-records-requests 5 https://apps.ecology.wa.gov/cleanupsearch/site/14715 Dale Walker March 14, 2025 Page 3 Characterizing the Site Ecology has determined your completed Site characterization is sufficient for setting cleanup standards and selecting a cleanup action. The definition of the lateral and vertical extent of Site impacts to soil, groundwater, and air was completed in accordance with MTCA by Site investigations conducted from March 2017 through August 2024. Enclosure A describes the Site. Setting cleanup standards Cleanup standards include cleanup levels, points of compliance, and applicable local laws and requirements. Ecology has determined the cleanup levels set for the Site meet the substantive requirements of MTCA. Cleanup Levels Soil MTCA Method A soil cleanup levels for unrestricted land uses are applicable to the Site (WAC 173- 340-900, Table 740-16). As documented in the Technical Memorandum, Terrestrial Ecological Evaluation dated January 28, 2025, the Site qualifies for a simplified Terrestrial Ecological Evaluation (TEE) per WAC 173-340-7492(2)(a)(i)7. The total area of soil contamination at the Site is not more than 350 square feet. Therefore, Method A soil cleanup levels do not require modification for protection of terrestrial species. Groundwater MTCA Method A groundwater cleanup levels, which are protective of potable groundwater use, are applicable to the Site (WAC 173-340-900, Table 720-1 8). Air MTCA Method B air cleanup levels for ambient and indoor air are applicable to the Site. Method B vapor intrusion (VI) screening levels for groundwater and sub-slab vapor are applicable to assess the air exposure pathways at the Site. Points of Compliance Soil The point of compliance is soils throughout the Site. 6 https://app.leg.wa.gov/WAC/default.aspx?cite=173-340-900 7 https://app.leg.wa.gov/wac/default.aspx?cite=173-340-7492 8 https://app.leg.wa.gov/WAC/default.aspx?cite=173-340-900 Dale Walker March 14, 2025 Page 4 Groundwater The point of compliance for groundwater is groundwater throughout the Site, from the uppermost level of the saturated zone extending vertically downward to the lowest depth that could potentially be affected. Air The point of compliance for air is ambient air throughout the Site. Selecting the cleanup action Ecology has determined the cleanup action you selected for the Site meets the substantive requirements of MTCA. The cleanup action included the following elements: • Removal of Site structures and vehicles associated with the former automobile salvage activities; • Excavation and off-Site disposal of contaminated soil; and • Collection of confirmation soil, soil vapor, and groundwater samples to document compliance with MTCA cleanup levels. Implementing the cleanup action Ecology has determined your cleanup meets the standards set for the Site. The cleanup action consisted of the following activities: • Clearing of structures and automobiles from the Site in 2017 and 2018; • During January through April 2019, establishment of 93 soil sampling grids (each 50 feet by 50 feet square), soil excavation at 20 grid locations, final mass excavation over the entire Property to achieve grades for Site redevelopment, and confirmation soil sampling to document compliance with MTCA soil cleanup levels; • Removal of 25,305 tons of contaminated soil from the Site and disposal at the Waste Management facility in Seattle; • Collection of soil vapor and indoor air samples to confirm the absence of a VI exposure pathway; • Collection of confirmation soil samples within the wetland buffer on the eastern Property boundary; and • Completion of 12 groundwater sampling events to confirm compliance with MTCA groundwater cleanup levels. Dale Walker March 14, 2025 Page 5 Decommissioning of Resource Protection Wells You must decommission resource protection wells9 installed as part of the remedial action that are not needed for any other purpose at the Site. Wells must be decommissioned in accordance with WAC 173-160-460.10 Listing of the Site Based on this opinion, Ecology will initiate the process of removing the Site from the Contaminated Sites List. The Site will be added to the No Further Action sites list. Limitations of the Opinion Opinion does not settle liability with the state Liable persons are strictly liable, jointly and severally, for all remedial action costs and for all natural resource damages resulting from the release or releases of hazardous substances at the Site. This opinion does not: • Resolve or alter a person’s liability to the state. • Protect liable persons from contribution claims by third parties. To settle liability with the state and obtain protection from contribution claims, a person must enter into a consent decree with Ecology under RCW 70A.305.040(4).11 Opinion does not constitute a determination of substantial equivalence To recover remedial action costs from other liable persons under MTCA, one must demonstrate that the action is the substantial equivalent of an Ecology-conducted or Ecology-supervised action. This opinion does not determine if the action you performed is substantially equivalent. Courts make that determination. See RCW 70A.305.080 12 and WAC 173-340-545.13 State is immune from liability The state, Ecology, and its officers and employees are immune from all liability, and no cause of action of any nature may arise from any act or omission in providing this opinion. See RCW 70A.305.170(6).14 9 https://app.leg.wa.gov/WAC/default.aspx?cite=173-160-410 10 https://app.leg.wa.gov/WAC/default.aspx?cite=173-160-460 11 https://app.leg.wa.gov/RCW/default.aspx?cite=70A.305.040 12 https://app.leg.wa.gov/RCW/default.aspx?cite=70A.305.080 13 https://apps.leg.wa.gov/WAC/default.aspx?cite=173-340-545 14 https://app.leg.wa.gov/RCW/default.aspx?cite=70A.305.170 Dale Walker March 14, 2025 Page 6 Termination of Agreement Thank you for cleaning up the Site under the VCP. This opinion terminates the VCP Agreement governing VCP Project No. NW3233. Questions If you have any questions about this opinion or the termination of the Agreement, please contact me at 425-324-1892 or michael.warfel@ecy.wa.gov . Sincerely, Michael R. Warfel VCP Site Manager Toxics Cleanup Program, NWRO Enclosures (2): A – Site Description, History, and Diagrams B – Basis for the Opinion: List of Documents cc: David McAlister, Eco Compliance Corporation (dmcalister@mcageosci.com) Matthew Herrera, City of Renton Planning Director (mherrera@rentonwa.gov) VCP Fiscal Analyst ECY RE VCP (FSD) (ecyrevcp@ecy.wa.gov) VCP Coordinator ECY RE NWRO VCP (vcp-nwro@ecy.wa.gov) Enclosure A Site Description, History, and Diagrams Site Description This section provides Ecology’s understanding and interpretation of Site conditions, and is the basis for the opinions expressed in the body of the letter. Site: The Site is defined by the following releases: • Total petroleum hydrocarbons in the gasoline, diesel and oil range (TPH-G, TPH-D and TPH-O), benzene, toluene, ethylbenzene and xylenes (BTEX), cadmium, chromium, arsenic, lead, zinc, nickel, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), tetrachloroethene (PCE), trichloroethene (TCE), 2-butanone (MEK), and acetone into soil; • TPH-G, TPH-D, TPH-O, benzene, toluene, PAHs, vinyl chloride, barium, cadmium, chromium, arsenic, copper, nickel, zinc, and lead into groundwater; and • Air-phase hydrocarbons, methane, benzene, naphthalene, 1,3-butadiene, chloroform, and acrolein into soil vapor. The Site is located at 3400 East Valley Road in Renton, Washington (the Property, Figure 1). Area and Property Description: The Property corresponds to King County parcel number 302305- 9067 which is 5.65 acres in size and located within the City of Renton Commercial Arterial (CA) zone. The Property is bounded by a wetland and State Route (SR)167 to the east; a recreational vehicle and boat storage business to the north; East Valley Road, an insulating glass supplier, and an automobile dealership to the west; and a commercial landscaping business to the south (Figure 2). Property History and Current Use: The Property was agricultural land as early as 1936 through the 1960s. By 1968 the Property was used as an automobile salvage yard. In 2008, as part of the widening of SR 167, a rock gabion retaining wall was installed just east of the Property. From approximately 1968 to 2019, the Property was occupied by a 4,000 square foot pre-fabricated steel warehouse building and an approximately 1,100 square foot radiator shop (Figure 3). Both structures were constructed on concrete slabs. The automobile salvage operation ended in 2017 and all remnants of that facility were removed by 2018. The Property was redeveloped as an auto dealership in 2019 including a 35,000 square-foot building, asphalt pavement, and a planting strip along the E Valley Road frontage. A 75-foot wide wetland buffer was created along the entire eastern portion of the Property (Figure 2 and Figure 6). Contaminant Sources: Potential contamination sources include residual fuel, waste oil, lubricants, and other automotive fluids from vehicles and the radiator repair shop; and chemicals used to clean automotive components as part of the salvage operation (Figure 3). Physiographic Setting: The Site is located in the Puget Lowland physiographic region, a broad basin bounded on the west and east by the Olympic and Cascade Mountains, respectively. The Site is situated near the eastern boundary of the valley formed by the Green River, which flows northward to discharge into Puget Sound in Seattle. Land surface of the Site and vicinity is flat at an elevation of approximately 20 feet above mean sea level. Surface/Stormwater System: Panther Creek is located approximately 400 feet east of the Site and flows north to discharge into the Black River, which then flows into the Green River. The confluence of the Black River and the Green River is located approximately 2.3 miles northwest of the Site. Stormwater at the Site flows to catch basins on the paved areas and is routed to an underground detention vault located in the southwest corner of the Property, which is connected to the City of Renton stormwater main on E Valley Road. Ecological Setting: The Site and surrounding area to the north, west, and south is covered by buildings and pavement, with occasional planting strips. A wetland located along the eastern Property boundary was delineated and mapped as part of Site investigations (Remedial Investigation / Feasibility Study (Revised), December 12, 2023). A 75-foot-wide wetland buffer along the western wetland boundary was established in coordination with the Washington State Department of Transportation (WSDOT), as shown on Figure 6. As noted in the text of this opinion letter, the Site qualifies for a simplified terrestrial ecological evaluation (TEE) and does not require modification of soil cleanup levels for protection of terrestrial species. Geology: Surficial soils at the Site are mapped as Tukwila Muck and Seattle Muck. Both of these soil types are poorly drained organic soils formed in herbaceous and woody deposits in depressions in river valleys and glacial till plains. Fill deposits consisting of silt, sand, gravel and varying types of automobile debris were encountered to an average depth of 5 feet below ground surface (bgs). Much of this fill was removed during Site redevelopment. Alluvial deposits common to the Green River Valley (silty clay, fine sand, and peat) are present beneath the fill to a depth of 20 feet bgs, the maximum depth explored at the Site. Groundwater: Depths to groundwater measured in Site monitoring wells range from 4 to 11 feet bgs. Groundwater flows to southwest, west, and northwest from the Site towards the Green River (Figure 4). Water Supply: Drinking water is supplied to the Property by the City of Renton. Renton’s drinking water is obtained from water supply wells in the Cedar Valley Aquifer, Springbrook Springs in south Renton, and an emergency intertie with Seattle Public Utilities. The nearest public water supply wellhead protection zone is located 1.1 miles northeast of the Site. Release and Extent of Contamination: A Site investigation completed in March 2017 identified petroleum hydrocarbons and metals in soil and groundwater above MTCA cleanup levels. After clearing the Property of structures and salvaged automobiles in 2017 and 2018, a Site-wide sampling and remediation effort was completed in 2019, as discussed in the text of this opinion letter (Figure 5). Confirmation soil samples were collected from excavations to confirm compliance with MTCA cleanup levels. Additional confirmation soil samples were collected in the wetland buffer along the eastern Property boundary in 2024 (Figure 6). Concentrations of TPH-D+O reported for samples R3B3 and R3B2 were2,000 and 2,130 milligrams per kilogram (mg/kg), respectively, compared to the MTCA Method A soil cleanup level of 2,000 mg/kg. These two sample locations area adjacent to former test pit R3 that was located within the WSDOT wetland east of the Property, where TPH-D+O was detected at 4,300 mg/kg in 2018. These exceedances of MTCA cleanup levels are likely attributable to highway related activities on SR 167. The southbound shoulder of SR 167 is located approximately 35 feet east of the eastern Property boundary. Eight monitoring wells were installed at the Site between August 2017 and March 2018 (Figure 4). Concentrations of total organic carbon (TOC) were detected in groundwater samples from upgradient monitoring wells MW-3 and MW-8 (45,900 micrograms per liter [µg/L] and 25,000 µg/L, respectively), compared to a typical concentration of 700 µg/L in natural groundwater. These background concentrations are attributable to the presence of organic peat deposits that underlie the Site. In a February 4, 2022, VCP Technical Assistance email, Ecology concurred with the use of silica gel cleanup (SGC) for groundwater samples , because the elevated natural TOC in the background wells clearly affected the TPH-D+O analysis results for this Site. Prior to advent of SGC use, TPH-D+O results without SGC were as high as 1,440 µg/L for MW-3 and 2,800 µg/L for MW-8, compared to the MTCA Method A groundwater cleanup level of 500 µg/L. Results from 12 groundwater monitoring events conducted from February 2019 through June 2022 confirmed compliance with MTCA cleanup levels for all Site contaminants of concern. A vapor intrusion (VI) survey was completed in 2020 that included collection of soil vapor samples beneath and adjacent to the floor slab of the automobile dealership building constructed on the Property in 2019. Sampling results confirmed the absence of an air exposure pathway via VI transport. 11 of 107 Figure 1. Site location map. Former South End Auto property. 3400 East Valley Road, Renton. Site location Enclosure A, Figure 1 Enclosure A, Figure 2 _______________________________________________________________________________________________________________ 29 of 191 (425) 271-5629 Figure 3. Junkyard operations. Former South End Auto property. 3400 East Valley Road, Renton. Source: PBS, 2018. Warehouse Radiator shop Enclosure A, Figure 3 Enclosure A, Figure 4 Enclosure A, Figure 5 TITLE: LOCATION: CHECKED:FIGURE: DATE: DRAFTED: PROJECT: D.McAlister McAlister GeoScience Eco Compliance Corporation 800 5th Avenue, Suite 101-313 Seattle, WA 98104 562-489-7908 DirtyProperty.com 2 Approximate Boring Locations N 3400 E. Valley Road Renton, Washington 98057 08-16-2024 18-1001Confirmation Borings Confirmation Borings Exceeding ESLs J. Landeros R1B1 R3B4 R3B1 R3B2 R3B3 R1B2 R1B3 R1B4 R1B5 R1B6 R1B7 R1B8 R3B5 R3B6 Enclosure A, Figure 6 Enclosure B Basis for the Opinion: List of Documents 1. Eco Compliance Corporation (Eco Compliance). Technical Memorandum, Terrestrial Ecological Evaluation. January 28, 2025. 2. Eco Compliance. Soil Investigation Report. October 4, 2024. 3. Department of Ecology (Ecology). Technical Assistance Regarding Proposed Additional Soil Sampling. January 2, 2024. 4. Eco Compliance. Remedial Investigation / Feasibility Study (Revised). December 12, 2023. 5. Ecology. Technical Assistance Regarding Site Characterization and Cleanup. August 31, 2023. 6. Eco Compliance. Technical Memorandum, Adjacent WSDOT Right-of-Way and Wetland Buffer Area Access Agreements. July 7, 2023. 7. Eco Compliance. Remedial Investigation / Feasibility Study. February 27, 2023. 8. Ecology. Technical Assistance Regarding Status of Site Characterization and Cleanup. August 25, 2022. 9. Eco Compliance. Groundwater Sampling Event Round 12. July 25, 2022. 10. Eco Compliance. Groundwater Sampling Event Round 11. May 5, 2022. 11. Ecology. Technical Assistance Regarding Proposed Groundwater Monitoring Changes. February 4, 2022. 12. Eco Compliance. Groundwater Sampling Event Round 10. , November 5, 2021. 13. Eco Compliance. Groundwater Sampling Event Round 9. September 8, 2021. 14. Eco Compliance. Groundwater Sampling Event Round 8. June 16, 2021. 15. Ecology. Technical Assistance Regarding Proposed Groundwater Monitoring Changes. February 10, 2021. 16. Eco Compliance. Groundwater Sampling Event Round 7. December 22, 2020. 17. Ecology. Technical Assistance Regarding Proposed Groundwater Monitoring Changes. November 16, 2020. 18. Ecology. VCP Opinion on Vapor Intrusion Assessment Report. October 1, 2020. 19. Eco Compliance. Groundwater Sampling Event Round 6. September 10, 2020. 20. Dixon Environmental Services LLC, Vapor Intrusion Assessment, 3400 East Valley Road, Renton, WA 98057, July 9, 2020. 21. Eco Compliance. Groundwater Sampling Event Round 5. June 25, 2020. 22. Ecology. VCP Opinion on Site Remedial Action. May 11, 2020. 23. Eco Compliance. Site Remediation Report (revised), April 10, 2020. 24. Eco Compliance. Response to Ecology’s Comments on Site Cleanup of Former South End Auto Property in Renton, April 2, 2020. 25. Ecology, Further Action Opinion Letter, March 25, 2020. 26. Eco Compliance. Site Remediation Report, November 5, 2019. 27. Eco Compliance. Groundwater Sampling Event Round 3, September 2019, October 3, 2019. 28. Eco Compliance. Revised Site Remediation Work Plan, August 14, 2019. 29. Eco Compliance. Revised Remedial Investigation (RI) Report, May 10, 2019. 30. Ecology, Initial Investigation Field Report, July 28, 2018. 31. PBS Engineering and Environmental, Inc., Hazardous Materials Survey Report, May 18, 2018. 32. Stemen Environmental, Inc., Remedial and Corrective Actions Project for the Commercial Property Located at 3400 Valley Road, Renton, Washington, April 23, 2018. 33. Stemen Environmental, Inc., Limited Phase II Environmental Site Assessment, Groundwater Monitoring Well Installation, and Groundwater Monitoring Informational Letter for the Commercial Property Located at 3400 East Valley Road, Renton, Washington, April 23, 2018. 34. Stemen Environmental, Inc., Limited Phase II Environmental Site Assessment for the Commercial Property Located at 3400 East Valley Road, April 23, 2017.