Stantec Consulting Services Inc. 3875 Atherton Road, Rocklin CA 95765-3716 April 16, 2019 File: 185750627 Attention: Holly Trujillo Sonoma County Community Development Commission 1440 Guerneville Road Santa Rosa, CA 95403-4107 Dear Ms. Trujillo, Reference: Summary of Findings, Phase I Environmental Site Assessment – Gateway Coalition Area, Eastern Block – 1 Sebastopol Road, 301 Chestnut Street Stantec Consulting Services Inc. (Stantec) has prepared this summary of findings of the Phase I environmental site assessment (Phase I ESA) entitled Gateway Coalition Area, Eastern Block – 1 Sebastopol Road, 301 Chestnut Street, Phase I Environmental Site Assessment (Stantec, January 16, 2019). The Phase I ESA was one of three assessments completed at a collection of properties located in Santa Rosa, California, herein referred to as the Gateway Coalition Area Properties. The intent of this letter is to summarize the findings and conclusions of the Phase I ESA completed for the sole reliance of Sonoma County Community Development Commission. This letter shall not be relied upon as a technical or legal surrogate in lieu of the complete Phase I document. We recommend the reader consult the complete, final document to fully understand the context of the findings summarized herein. The Phase I ESA identified recognized environmental conditions (RECs) and historical RECs (HRECs) associated with current or historical on-site and off-site features. Based on the REC, HRECs, and other documented or potential environmental concerns, in combination with anticipated redevelopment of the site, Stantec recommends that a comprehensive Phase II ESA be completed to further assess subsurface conditions. Description of specific Phase II assessment activities are beyond the scope of this document. The following sections summarize RECs and HRECs associated with the properties. Site features and locations of RECs/HRECs are illustrated on the attached figures. RECs Pertaining to Current or Historical On-Site Features McMinn Avenue Superfund Regional Study Area The Site is located within the historical McMinn Avenue Superfund Regional Study Area. In 1992, multiple investigations identified hazardous substances (fuel products, chlorinated hydrocarbons, volatile organic compounds) in groundwater and soil gas near and downgradient of the intersection of Sebastopol Road and McMinn Avenue (located approximately 3,000 feet west of the Site). State and federal regulators established a ‘Local Study Area’ within a 2,000-foot radius from the intersection, and a ‘Regional Study Area’ within a one-mile radius from the intersection. The Site is located within this one-mile radius. Subsequent investigations identified numerous sources of chemical impacts to soil and groundwater including a Chevron bulk fuel terminal, a retail gasoline station, and several distinct sources of VOCs. Due
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Stantec Consulting Services Inc. 3875 Atherton Road, Rocklin CA 95765-3716
April 16, 2019 File: 185750627
Attention: Holly Trujillo Sonoma County Community Development Commission 1440 Guerneville Road Santa Rosa, CA 95403-4107
Dear Ms. Trujillo,
Reference: Summary of Findings, Phase I Environmental Site Assessment – Gateway Coalition Area, Eastern Block – 1 Sebastopol Road, 301 Chestnut Street
Stantec Consulting Services Inc. (Stantec) has prepared this summary of findings of the Phase I environmental site assessment (Phase I ESA) entitled Gateway Coalition Area, Eastern Block – 1 Sebastopol Road, 301 Chestnut Street, Phase I Environmental Site Assessment (Stantec, January 16, 2019). The Phase I ESA was one of three assessments completed at a collection of properties located in Santa Rosa, California, herein referred to as the Gateway Coalition Area Properties.
The intent of this letter is to summarize the findings and conclusions of the Phase I ESA completed for the sole reliance of Sonoma County Community Development Commission. This letter shall not be relied upon as a technical or legal surrogate in lieu of the complete Phase I document. We recommend the reader consult the complete, final document to fully understand the context of the findings summarized herein.
The Phase I ESA identified recognized environmental conditions (RECs) and historical RECs (HRECs) associated with current or historical on-site and off-site features. Based on the REC, HRECs, and other documented or potential environmental concerns, in combination with anticipated redevelopment of the site, Stantec recommends that a comprehensive Phase II ESA be completed to further assess subsurface conditions. Description of specific Phase II assessment activities are beyond the scope of this document.
The following sections summarize RECs and HRECs associated with the properties. Site features and locations of RECs/HRECs are illustrated on the attached figures.
RECs Pertaining to Current or Historical On-Site Features
McMinn Avenue Superfund Regional Study Area
The Site is located within the historical McMinn Avenue Superfund Regional Study Area. In 1992, multiple investigations identified hazardous substances (fuel products, chlorinated hydrocarbons, volatile organic compounds) in groundwater and soil gas near and downgradient of the intersection of Sebastopol Road and McMinn Avenue (located approximately 3,000 feet west of the Site). State and federal regulators established a ‘Local Study Area’ within a 2,000-foot radius from the intersection, and a ‘Regional Study Area’ within a one-mile radius from the intersection. The Site is located within this one-mile radius. Subsequent investigations identified numerous sources of chemical impacts to soil and groundwater including a Chevron bulk fuel terminal, a retail gasoline station, and several distinct sources of VOCs. Due
April 16, 2019 Holly Trujillo Page 2 of 4
Reference: Summary of Findings, Phase I Environmental Site Assessment – Gateway Coalition Area, Eastern Block – 1 Sebastopol Road, 301 Chestnut Street
to the nature, extent, and magnitude of impacts to shallow groundwater and soil vapor in these areas, the overlap of the investigation area with the Site, and the ongoing status of groundwater contamination, the McMinn Avenue Superfund Study Area constitutes a REC.
Historical Boiler and Storage Tanks at 1 Sebastopol Road
Based on review of a 1969 Sanborn fire insurance map, a boiler was historically located immediately north of the former mill building at 1 Sebastopol Road. Four unlabeled tanks were identified immediately west of the boiler and were potentially used to store fuel for the boiler. The former presence of the boiler and the likely storage and use of oil to fuel the boiler constitute a REC.
Historical Automotive Repair at 301 Chestnut Street
The property at 301 Chestnut Street contains a building that was formerly used as an auto repair and tire shop. Surface staining was observed in the service bay of the building, and an aboveground electric chain-operated lift was also observed. Evidence of belowground lifts was not identified. This past use of the property as an auto repair facility, and the possibility of past releases of automotive fluids to shallow soils constitute a REC.
Santa Rosa Fire Department Notice of Violation at 1 Sebastopol Road
Review of Santa Rosa Fire Department (SRFD) records revealed a Notice of Violation and cease and desist letter issued to Gold Towing (operating at 1 Sebastopol Road) on November 16, 2000 for spray painting auto body parts without a spray booth and without a SRFD permit. Due to the improper use of the property for spray painting auto body parts without proper protective measures and permitting for an unknown period of time prior to issuance of violation, and the possibility of impacts to surface and shallow soils at the property, this past use constitutes a REC.
Gasoline Release at 1 Sebastopol Road (HREC)
According to State Water Resources Control Board records, a gasoline release was discovered at 1 Sebastopol Road in July 1998 following removal of two fuel underground storage tanks (USTs) and piping. A 10,000-gallon diesel UST was removed from the northeastern portion of the 1 Sebastopol Road property, and a 550-gallon gasoline UST from the south-central portion of 1 Sebastopol Road near the former mill building. Site investigations conducted in January 2001 confirmed impacts to soil and groundwater. In November 2005, limited over-excavation of soil was completed at one former UST location, and additional testing was performed between 2001 and 2013. The leaking underground storage tank (LUST) case was closed on April 18, 2014. The former LUST at the Site is considered an HREC.
RECs Pertaining to Current or Historical Off-Site Features on Neighboring Parcels
Historical Fuel Release at 8 Sebastopol Road (50 feet south of site)
The property at 8 Sebastopol Road previously contained fuel USTs and has an associated cleanup case. After the facility closed in 2000, groundwater monitoring indicated that concentrations of petroleum hydrocarbons were stable or declining. A land-use covenant has been recorded for all or a portion of the property that prohibits excavation of remaining contaminated soils and extraction of groundwater without
April 16, 2019 Holly Trujillo Page 3 of 4
Reference: Summary of Findings, Phase I Environmental Site Assessment – Gateway Coalition Area, Eastern Block – 1 Sebastopol Road, 301 Chestnut Street
regulatory approval. Based on proximity to the site and documented releases to soil and groundwater, this property is considered a REC.
Historical Fuel Release at 121 Chestnut Street (450 feet south of site)
Two leaking underground storage tank (LUST) cases are associated with the property at 121 Chestnut Street, one of which remains an open case due to remaining groundwater impacts. The property operated by Mobil Oil as a bulk plant between 1963 and 1982, and significant impacts to groundwater have been documented during routine monitoring events (i.e., up to 11,000 micrograms per liter [µg/l] gasoline). Calculated groundwater flow is generally north-northwest and away from the site; however, based on the magnitude of chemical impacts to groundwater and open regulatory status, the property is considered a REC.
Historical Fuel Release at 109 Chestnut Street (550 feet north of the site)
The property was formerly an aboveground oil storage area associated with the former Mobil Oil bulk plant located at 121 Chestnut Street and remains an open regulatory case due to petroleum hydrocarbons impacting soil and groundwater. Investigations completed in 2005 and 2006 identified the presence of free-phase petroleum hydrocarbons in groundwater. A 2008 work plan for additional assessment appears to have not been completed. Based on the magnitude of remaining petroleum impacts to groundwater, the undefined extent of groundwater impacts, and the regulatory status of this case, the property is considered a REC.
Historical Fuel Release at 205 Chestnut Street (350 feet north of the site)
An open regulatory case due to petroleum hydrocarbon impacts to groundwater is associated with the property at 205 Chestnut Street, and significant impacts to groundwater have been documented during routine monitoring events (i.e., up to 200,000 µg/l diesel reported in March 2018). Calculated groundwater flow is generally north-northwest and away from the site; however, based on the magnitude of chemical impacts to groundwater and open regulatory status, the property is considered a REC.
Historical Fuel Release and Bulk Fuel Storage at 111 Sebastopol Road (100 feet west of the site)
The property at 111 Sebastopol Road historically operated as an automobile fueling station and a bulk fuel storage facility between approximately the 1930s and 1986. A closed LUST case is associated with the property, with cleanup and verification monitoring completed in 2000. Due to the documented historical site use, prior cleanup activities, and proximity to the site, the property is considered an HREC.
Additional Findings of Note
The Phase I ESA identified additional conditions of potential environmental significance that are not considered RECs but that may warrant additional consideration. Please refer to the Phase I ESA for a complete list of these conditions. Two pertinent findings related to historical land use and regulated building materials are summarized below.
April 16, 2019 Holly Trujillo Page 4 of 4
Reference: Summary of Findings, Phase I Environmental Site Assessment – Gateway Coalition Area, Eastern Block – 1 Sebastopol Road, 301 Chestnut Street
Potential Soil Impacts Due to Historical Industrial Use
The site and surrounding areas were first developed in the early 1900s during a time when lead-based paint was widely in use. Furthermore, the Site is located in an area of extensive urban development and is directly bordered to the west by a railroad right-of-way in use since at least 1908. Ambient concentrations of heavy metals (including lead) and carcinogenic compounds (such as polycyclic aromatic hydrocarbons) are frequently found to be elevated in shallow surface soils in industrialized areas, due to cumulative effects of vehicle exhaust and historical industrial operations, as well as hazardous materials commonly associated with long-term industrial use. Users of the site should consider the potential presence of hazardous compounds in shallow soil, and future reuse should consider mitigating direct contact with shallow soils, especially for planned or potential future use by sensitive populations such as children.
Potential Presence of Regulated Building Materials
Based on historical aerial photographs and Sanborn maps for the Site, several of the existing buildings at the Site were constructed in the 1950s, 1960s and 1970s when asbestos and lead-based paint were commonly used construction materials. It is possible that existing buildings at the Site may contain hazardous building materials. Additionally, based on Sanborn maps, additional buildings were present at the Site but demolished in the past. It is possible that demolition of these historic buildings may have resulted in deposition of residual asbestos and lead-containing materials onto surface soil at the Site. Users of the Site should consider the potential presence of hazardous compounds in existing buildings at the Site as well as shallow soil in the vicinity of previously demolished buildings, and the possible presence of such compounds should be managed appropriately during future reuse.
CLOSING
Please contact the undersigned if you have any questions regarding this document.
Disclaimer: Stantec assumes no responsibility for data supplied in electronic format. The recipient accepts full responsibility for verifying the accuracy and completeness of the data. The recipient releases Stantec, its officers, employees, consultants and agents, from any and all claims arising in any way from the content or provision of the data.
1 Sebastopol Road301 Chestnut SteetSanta Roas, CA
Prepared by JB/WC on 2019-01-10Technical Review by CA on 2019-01-11
Disclaimer: Stantec assumes no responsibility for data supplied in electronic format. The recipient accepts full responsibility for verifying the accuracy and completeness of the data. The recipient releases Stantec, its officers, employees, consultants and agents, from any and all claims arising in any way from the content or provision of the data.
1 Sebastopol Road301 Chestnut StreetSanta Roas, CA
Prepared by JB/WC on 2019-01-10Technical Review by CA on 2019-01-11
Independent Review by ND on 2019-01-11
ProjectLocation
LegendApproximate Easterrn Block Property Area
Site Identified as a REC for the Property
Sebastopol Road
Railro
ad Tr
acks
Robe
rts Av
enueJoe Rodota Trail
Holbrook Street Highway 12 E
Zedrick Property111 Sebastopol Rd.HREC: Closed LUST SiteHREC: Former use for fuel storageand automotive repair
Point St. George Fisheries8 Sebastopol Rd. REC: Residual TPH impacts and land-use covenant
Standard Oil Bulk Facility205 Chestnut St.REC: Open case
Historical McMinn Ave Superfund Regional Study Area(Centered on the intersection of McMinn Avenue and Sebastopol Road) Historical VOC and fuel impacts to soil vapor and shallow groundwater
Shell Oil Bulk Facility238 Roberts Pl.REC: Former bulk oil plant previously used to store large fuel and oil ASTs
Gateway Eastern Block Sitewide REC and PVEC (Not Depicted on Figure)
NOTE: Please refer to Stantec Phase I ESA report (January 2019)
for complete discussion of recognized environmental conditions.
