SR0084836 (4) - Laserfiche WebLink

Home Browse Search

aecom.com Our Reference 60632236 2/10 Gold Bond contracted with American Environmental Management Corp. (AEMC) to remove the eight USTs during the week of September 29, 1986 (AEMC 1986). The closure operations were permitted by San Joaquin County Public Health Services, Environmental Health Division (the County) and observed by staff from the County and RWQCB. No staining was observed in the product tank pit, but a slight odor was detected. Some staining and odor were observed in the waste tank pit. Post-removal sampling of soil from the tank pits showed only low levels of five chemicals including toluene (at less than 0.1 milligrams per kilogram) (AEMC 1986). Concentrations of the chemicals detected in the soil samples collected from the tank pit were below regulatory guidance levels for UST corrective action, indicating that soil removal was not necessary (AEMC 1986). In January 1987, RWQCB and the County agreed that the tank pits could be backfilled. In early 1988, California Department of Health Services (DHS) concluded the tank closure was complete and deferred to the County to issue a certificate of closure to Gold Bond (DHS, Toxic Substances Control Division, Northern California Section 1988). Dopaco vacated the Site in 1988 (Geosyntec 2015a). In 1997, Newark (the new owner of the property) requested a closure letter from RWQCB for the eight USTs removed in 1986 (Rogge MJ 1997). RWQCB responded in early 1998 stating that additional soil and groundwater samples were required from the area of the former USTs to complete the closure request (Anderson PA 1998). No further activity with respect to closure of the former USTs occurred until 2005, when a soil and groundwater investigation was performed by Advanced GeoEnvironmental, Inc. (AGE) on behalf of a prospective buyer of the property (AGE 2005). In 2006 and 2008, MACTEC Engineering and Consulting, Inc. (MACTEC) performed additional investigations in the area on behalf of Newark (MACTEC 2006; 2008). According to these investigations, soil and groundwater impacts were identified in the northwestern, southwestern, and southeastern corners of the Site. In the northwestern area, toluene and other petroleum compounds were identified in the deeper soil (15 feet bgs and deeper) and groundwater (Geosyntec 2015a). Between 2008 and 2012, soil vapor, soil, and groundwater samples were collected from beneath the plant building, which was demolished in 2011, and near the northwestern exterior corner of the building. In November 2012, Geosyntec installed three groundwater monitoring wells (DMW-1, DMW-3, and DMW-4) screened across the A-zone sand (i.e., 30 to 40 feet bgs). Regular sampling of these wells commenced in March 2013 (Geosyntec 2015a). Removal of the secondary toluene source occurred from February 25 to February 27, 2014, during which approximately 300 cubic yards of soil was excavated, stockpiled, profiled, and disposed of as non- hazardous waste (Geosyntec 2015a). In February 2014, following excavation of the secondary toluene source, Geosyntec installed groundwater monitoring wells DMW-5A and DMW-5B adjacent to the excavation footprint. In May and June of 2014, Geosyntec advanced two cone penetrometer test (CPT) borings, collected 12 grab groundwater samples, and installed three groundwater monitoring wells (DMW-6A, DMW-6B, and DMW-6WT) off-site and downgradient from the former toluene source area. Regular sampling of these wells commenced in June 2014 (Geosyntec 2015a). Regular sampling of the eight Site groundwater monitoring wells continued through December 2014. Based on the results of this monitoring and the off-site characterization, gasoline and diesel were added to the list of potential contaminants of concern (COCs) for the Dopaco Area (Geosyntec 2015b). Dopaco was acquired by Cascades Inc. (Cascades) in 2014. In January 2015, on behalf of Cascades, Geosyntec submitted a Request for Closure for Toluene (Geosyntec 2015a). In April 2015, RWQCB issued a letter of No Further Action Required for Toluene at the Site listed under RWQCB Case Number (#) 391187 (aka Dopaco Case #1) (RWQCB 2015); however, all other COCs detected in groundwater within the Dopaco Area during the toluene investigation were listed under