Laserfiche WebLink
PUBLIC HEAL'T'H SERVICES �4RR4�liY <br /> SAN JOAQUW COUNTY �� o <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst,M.D.,M.P.H., Health Officer <br /> ' 304 East Weber Avenue,Third Floor a Scockton, CA 95202 <br /> 209/468-3420 <br /> 1 <br /> ROBERT BOUST <br /> ' UNOCAL CORPORATION JUN 2 6 1998 <br /> 2121 N CALIFORNIA BLVD SUITE 250 <br /> WALNUT CREEK CA 94596 <br /> ' RE UNOCAL SITE CODE 1213 <br /> 1665 Pacific Avenue <br /> ' Stockton, CA <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has <br /> ' reviewed the"Vertical Fuel Hydrocarbon Plume Delineation Hydropunch Investigation/Piezometer <br /> Installation'work plan dated May 26, 1998, prepared by ARCADIS GeraghtyR Miller, Inc for the <br /> above referenced site <br /> ' PHS/EHD does not agree that the investigation proposed will complete the site investigation <br /> necessary to provide data for the preparation of a corrective action plan (CAP) <br /> UNOCAL onginally leased the site in January 1947 and removed underground storage tanks <br /> (USTs) in March 1988 It was stated that the station was completely remodeled in 1967 <br /> According to PHS/EHD file records, the USTs removed in March 1988 were installed at that time <br /> ' The location of the USTs operated pnor to the 1967 station remodel has not been shown on site <br /> maps The location of this former UST system should be shown so its potential as a source of the <br /> contamination can be evaluated with information gathered from the site investigation to date <br /> ' In 1978, depth to groundwater in the area of this site was about 60 feet below surface grade(bsg) <br /> PHSIEHD has not reviewed records on depth to groundwater pnor to 1978 In 1986 and currently, <br /> depth to groundwater at the site waslis about 25 feet bsg It is not known when the unauthonzed <br /> ' release of petroleum hydrocarbons occurred Therefore, the depth to groundwater at the time of <br /> the release(s) is not known <br /> Soil contamination was documented at a depth of 51 feet bsg by a sod sample collected at that <br /> ' depth dunng the bonng for the installation of vapor well VVIR The vertical extent of soil <br /> contamination has not been defined and the proposed work will not provide that definition <br /> Petroleum hydrocarbons that have absorbed to the soil and have not dissolved into the <br /> t groundwater yet are a continuing source of groundwater contamination The investigation should <br /> not be limited to current dissolved-phase hydrocarbons The potential for future releases to the <br /> groundwater from contaminated sod should also be investigated by sampling of the sod above <br /> and below current groundwater until the vertical extent of soil contamination has been <br /> demonstrated <br /> The results of the soil samples collected from vapor extraction well VVV2 revealed soil <br /> ' contamination from 6 feet to 51 feet bsg The results of soil samples collected from monitonng <br /> wells MW4 and MW5 and soil bonng 136 revealed non detectable soil contamination, although the <br /> detection limits were higher than are currently acceptable Although, the groundwater gradient <br /> ' has been to the northeast, groundwater samples from MW4 have shown petroleum hydrocarbon <br /> ' A Divuion of San Joaquin CountyHeslrh Care <br /> 5uv ca <br />