ARCHIVED REPORTS_XR0011740 - Laserfiche WebLink

Home Browse Search

Phase I Environmental Site Assessment ` City of Stockton Multi-Modal Station/Shopping Center Page 18 28 4 feet below the tops of the well casings The groundwater gradient was found to be 0 007 ft/ft to the southeast TPH-G and TPH-D were detected in all of the wells ranging from. 1 4 to 380 ing/L and 0 19 to 47 ing/L, respectively BTEX were also detected in all of the wells at concentrations as high as 4,600, 97,000, 9,700, and 41,000 gg/L, respectively No additives or oxygenates were detected in any of the wells at or above the laboratory reporting limits Laboratory results from the December 26, 2000 sampling indicated that TPH-G and TPH-D were detected in the sample from MW-3 at 0 18 and 0 087 mg/L, respectively Toluene and total xylenes were detected in the samples from MW-2 and MW-3 at concentrations up to 7 0 tig/L (toluene) and 1 5 µg/l,(total xylenes) The highest concentrations of hydrocarbons occur in the area of the forger USTs The lateral extent of the impacted groundwater has been defined to the southeast and west of the former UST area The vertical extent of the contaminated groundwater has not been defined Currently approximately seven feet of water is above the tops of the well screens at monitor wells MW IA, MW-3, and MW-4 Stockton Armature and Motor Works 646 S California Street There is a file entry listing the site as an inactive small hazardous waste generator Former ARCOService Station#4493 205 N. Center Street The former service station was destroyed during the first quarter 1999 The site is currently vacant The site is located on property identified as Weber Point The Stockton Channel is adjacent to the site to the south In 1984, three 12,000-gallon USTs were installed at the site The tanks were tightness-tested 13 times between 1986 and 1996 On September 19, 2000, groundwater monitoring activities took place on site The depth to water was estimated at 12 5 to 14 5 feet The groundwater gradient was estimated to be 0 012 ft/ft to the southeast s TPH-G was detected in three of the seven wells at concentrations ranging from 75 7 to 3,460 µg/L Benzene was detected in five of the wells at concentrations ranging from 0 512 to 234 gg/L MTBE was detected in three wells at concentrations ranging from 102 to 1,710 µg/L Cis-1,2-Dichloroethene was detected in five of the wells at concentrations ranging from 3 4 to 361 µg Trichloroethene was detected in three of the wells at concentrations ranging from 10 8 to 185 gg/L A hydraulic gradient at the site was estimated to be 0 012 ft/ft Chevron Service Station 139 S Center Street Groundwater monitoring took place on December 4, 2000 The depth to groundwater ranged from 22 to s 23 feet bgs The groundwater gradient was 0 003 ft/ft to the southeast Five of the nine wells on site were sampled for this event The other four were not sampled as they were inaccessible A groundwater sample was not collected from MW-9 due to the presence of separate phase hydrocarbons in the well ` TPH-G was detected in MW-1 at a concentration of 81 gg/L Benzene was not detected in the four wells sampled MTBE was detected in MW-2 at a concentration of 0 73 gg/L City of Stockton Redevelopment Agency Property(Shell-branded Service Station) 141 N El Dorado Street A groundwater extraction system was in operation at the site from March 2, 1993 through September 5, 1 1995 Several soil vapor extraction systems have been in operation at the site The estimated purgeable petroleum hydrocarbons removed in pounds is 37 (liquid phase) and 3277 (vapor phase), for a total of 3314 pounds x n L� CONDOR