SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

lu MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 255-3000 Sacramento, CA 958J34-0098 CALVE F: 8-494-3000 TO: E , GLB FROM: Heidi Barr ` Underground Tanks Unit 'I DATE. 21 September 1994 SIGNATURE: SUBJECT' REQUEST FOR CLOSURE, J.B. TERMINAL, 5700 GRANTLINE ROAD, TRACY, SAN JOAQUIN COUNTY I �`vve`received'a°'-closure report'iff'December"1993;which c'onfains"'all of the information required in Appendix-B of the Tri-Regiohal Recommendations. Review of the file shows that two 550 gallon underground fuel storage tanks, one leaded gasoline tank and one unleaded gasoline tank, were removed in October 1987. During tank removal, field sampling by RESNA, and laboratory soil analyses indicated concentrations of Total Petroleum Hydrocarbons as gasoline (TPHg) from non-detect (ND) to 6.1 parts per million (ppm), and benzene, toluene, ethyl benzene, and xylenes (BTEN) levels from ND to 2.0 ppm. Ethylene dibromide and total lead were ND. Soil sample depths were not given and the depth to ground water (DTM was not measured. Since the site investigation began, in March 1990, five monitoring wells have been installed. The ground water gradient has been calculated to flow in the northeast direction at`0.004 ft/ft. During ground water sampling, petroleum hydrocarbons as high as 29,000 parts per billion (ppb) were consistently detected in MW-1. The other two wells have remained ND-since October 1990. in March 1993, additional contaminated soil was excavated to 15 feet below ground surface (bgs). Excavation proceeded until no contamination was evident. Approximately 200 cubic yards of soil was removed from the excavation pit. Five soil confirmation sidewall samples were collected from the capillary fringe,�at depths_of �0'7' to1010°which_indicated.no. ..r.,,. �. ._.- _. petroleum hydrocarbons were present. Wo samples were taken from the bottom of the pit. r. Clean overburden was separated from contaminated soil prior to stockpiling on-site. Mw-1 was destroyed, during the March 1993 excavation, under permit from San Joaquin Y 9 � County Public Health Department and was not replaced because MW-4 is approximately 35 feet down gradient of Mw-1. On 9 April 1993, the tank pit was backfilled using pea gravel. Ground water monitoring in April, July, and October 1993, showed non-detectable. levels of contamination in all wells. in December 1993, a request for closure was submitted and no work has been performed at the site since. The San Joaquin County Health Services Department (County) closed the site on 12 May 1995. The monitoring wells were decommissioned prior to closure. HB