Laserfiche WebLink
! c <br /> 5 <br /> c6 <br /> Mr. Kyle Christie <br /> January 30, 1991 <br /> Page 12 <br /> Conclusions <br /> The analytical results from all of the wells sampled indicate that the hydrocarbon impacted <br /> groundwater remains primarily beneath or immediately adjacent to ARCO Station 434. Of the <br /> 12 wells sampled,seven wells showed benzene concentrations lower than or the same as benzene <br /> concentrations identified during May 1990. The approximate 5.5-foot drop in water elevations <br /> may account for the relative reductions in benzene concentrations. As groundwater elevations <br /> drop, some benzene remains in the vadose and capillary fringe zones and may be relatively <br /> inaccessible to groundwater. <br /> In four of the wells sampled benzene concentrations have increased from the concentrations <br /> identified in May 1990. These wells are mainly located down-gradient and may indicate. <br /> migration of hydrocarbon impacted groundwater. <br /> Ethylbenzene,toluene,and xylenes concentrations in groundwater from all on-and off-site wells <br /> have remained non-detected or below the DHS MCLS. <br /> Should you have any questions regarding this report, please contact me or Ms. Janice Hubbard <br /> at (916) 444-0123. <br /> Very truly yours, <br /> BROWN AND CALDWELL <br /> Jay . Lucas <br /> project Manager <br /> JCL:JH:mkw <br /> Enclosures <br /> cc/enc: Mr. Gordon Boggs, California Regional Water Quality Control Board, <br /> Central Valley Region <br /> Ms.Laurie Cotulla, San Joaquin County Local Health District <br /> Mr. Chris Winsor, ARCO Products Company <br /> Brown and Cattlwell <br />