Laserfiche WebLink
PETITION FOR SITE CLOSURE <br /> UNOCAL SERVICE STATION # 6348 <br /> 3788 TRACY BOULEVARD, <br /> TRACY, CALIFORNIA <br /> SITE HISTORY <br /> This station was originally constructed by Unocal in 1972 It operated as a "full <br /> service" station until 1976 when it was converted to a self service facility The station <br /> ' was closed to business in 1992 Demolition of the station was undertaken in 1993 <br /> ' The investigation and remediation of the site took place in four separate phases <br /> beginning in July of 1991 The significant activities of each phase are summarized in <br /> the following <br /> ' 1) PRELIMINARY PHASE 1 AND INITIAL SITE BORINGS JUNE - JULY, 1991 <br /> ' The preliminary Phase 1 Site Assessment was completed by PHR Environmental <br /> Consultants That investigation reviewed the relevant site history, potential <br /> environmental issues in the surrounding area, and identified the operational features <br /> and practices of the station which could have resulted in environmental releases <br /> Based on the information contained in that investigation, Mittelhauser Corporation <br /> installed a series of four monitoring wells and drilled 12 additional borings to obtain <br /> soil samples from areas of concern, including the underground storage tanks, pipelines <br /> fuel dispensers, etc The analytical results of the soil borings are included in Table 1 <br /> 2) UNDERGROUND STORAGE TANK/PIPING REMOVAL AND SOIL SAMPLING <br /> ' In January of 1993, the underground storage tanks, fuel dispensers and subsurface <br /> piping, and automobile hoist were removed At the time of removal, the tanks <br />' appeared to be in good condition The excavation for the tanks intersected the <br /> shallow water table and approximately 1 ,320 gallons of pit water were pumped out <br /> and disposed of at that time Field notes at the time of excavation indicated that <br />' there was a "partial scum" on the surface of the groundwater It is not known if this <br /> was related to hydrocarbons The tank pit excavation was screened using a <br /> photoionization detector to locate hydrocarbon-impacted sods and to guide the <br />' sampling program The laboratory analysis of the pit bottom and sidewall soil samples <br /> showed localized soil contamination centered around the western end of the <br /> northernmost underground tank The highest soil sample taken from the tank pit <br /> showed gasoline concentrations at 1,200 parts per million (ppm) One pipeline sample <br /> showed concentrations of 3,500 ppm. <br /> 216OR009 wP 1 /flittelhauser <br /> C 0 R P 0 R n i 1 0 N <br />