SITE INFORMATION AND CORRESPONDENCE

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sent By BASELINE; � 510 420 1707; Nov-9--- 16,23; Page 3129 C I :'t U N 0 V 16 1999 EXECUTIVE S U MMAR'FNVI RON MENTAL HEALTH It PERMIT/ SERVICES The purpose of this Preliminary Endangerment Assessment Equivalent document prepared for the Weber Block property located in Stock.-ton,Califomia is to determine whether current or past waste management practices at the site(or immediately off-site)have resulted in the release or threatened release of hazardous substances that pose a threat to public health and the environment. This report was prepared in substantial compliance with the California Department of Toxic Substances Control (DTSC)Preliminary EndangermentAssessment Guidance Manual(DTSC, 1994)and'dirccdon from DTSC staff. The site is currentlyowned b the Cit of Stockton,which intends to develop a water squarelpublie y y meeting place at the site, The site is currently operated as a vacant former parking area and is surrounded by a chain link fence. The site is placarded as no trespassing, Parking is no longer permitted on the site as the piers upon which the parking lot rest are failing. Historic uses of the site include freight sheds and transportation loading terminals on the northern and southern portion of Weber Block,and an open Stockton Channel extending across the center of the property to El Dorado Street prior to 1950. it is unknown what,if any,hazardous materials may have been stored in the freight sheds and loading terminals and any waste management practices that may have been implemented at the time. By the early 1950s,the Stockton Channel was covered by a parking lot supported on treated wood piles. Shell Oil Company operated a gasoline service station onthe northeastern portion of the property from approximately 1955 tv the early 1980s; Thisportion of the property was later occupied by the Bridgestone Tire and Automobile Repair facility. All underground tanks associated with these former land use autivitics have been removed from the northeastern portion of the property. i Numerous environmental investigations have been conducted at the property associated with the former gasoline station and tine and automobile repair facility in the northeastern portion'of the property. A soil vapor extraction system operated on the northeastern portion of the property from 1992 to 1996. This system was augmented from 1993 to 1995 with a groundwater extraction system. A groundwater oxygenator system was on-line from 1994 to approximately 1996. These systems are no longer operated at the site. The northeastern portion of the property is bcing considered for ease closure by the San Joaquin County Public Health Services, Environmental Health Division. A Phase II investigation was conducted in 1995 for the remainder of the property, under oversight by DTSC and the U.S. Environmental Protection Agency (U.S. EPA). The Phase II investigation was completed under a Brownfield5 Pilot Project Grant from U.S. EPA. The Phase I1 investigation identified iron, lead,arsenic(one sample), and henzo(a)pyrene in some soil samples exceeding U.S, Environmental Protection Agency preliminary remediation goals for ` residential site users, One on-site groundwater sample collected at the site as part of the Phase II E investigation exceeded the maximum contaminant limit (MCLs) for drinking water for aluminum' and lead. The Phase 11 investigation also identified methyl tent butyl ether, benzene, and other chlorinated volatiles exceeding applicable MCLs in an offsite groundwater sample collected immediately upgradient of the site. I -viii-