Laserfiche WebLink
O., � 5 - 'F7"' <br />�.� <br /> December 18, 1991 <br /> Former Unocal Station 2859, Stockton, California <br /> E <br /> Rancho Cordova,California(Hazardous Waste Testing Laboratory No. E773). Cumulative <br /> results of analyses are summarized in Table 2. Copies of the laboratory analysis repo.t-are <br /> included with this report. <br /> Results of laboratory analyses indicated"!PFlg was detected in the samples collected from <br /> weils MW-4 and NlW_5 at concentrations of 180 parts per billion (ppb) and 120 ppb, <br /> respectively. Benzene, toluene, and total xylene isomers were not detecrL;d in the water <br /> samples collected from inthle tram le collected from wellW-4 and IvINV-5. MW-4,but was not detected in <br /> e was detected at a <br /> concentration of LQ pp P <br /> a* the sample collected from well MW-5. <br /> WORK IN PROGRESS <br /> A work plan has been prepared and submitted to San Joaquin County, Public Health <br /> Services. Environmental Health Division for drilling vapor-extraction wells onsite and <br /> conducting a vapor-extraction test. Tile vapor-extraction test will be performed at Unocal's <br /> request to evaluate whether remediation of soil using vapor-extraction is feasible. Unocal <br /> has requested r•ithorization from the City m Stockton Public Works Department to install <br /> an additional groundwater monitoring %,,ell downgradient from wells 1IW-4 and MW-5. <br /> .w CONCLUSIONS AND RECOMMENDATIONS <br /> Results indicated BTEX concentrations were below method detection limits in the water <br /> samples collected from wells NIW-4 and %iW-5, except for 1 ppb of ethylbenzene detected <br /> in the sample collected from well MW-4. Based on these analyses, we recommend <br /> continuing quarterly monitoring. We have scheduled the next sampling for the week of � <br /> November 18, 1991. <br /> We recommend a copy of this report be forwarded to Nis. Diane Hinson of the San Joaquin <br /> Local Health District, P.O. Box 2009, Stockton. California 95201, and �iMs. Elizabeth A. <br /> Thayer of the California Regional Nater Qualitv Control Board, Central Vallev Region, <br /> 3443 Routier Road, Sacramento. California 95827-3098. <br /> 0830nis 3 <br /> 3aor2-7 <br />