Laserfiche WebLink
''R"= rw+s-�r�• ee"�T.�+asa�"�.�t�'Y-�^ `"p' .w�` s�,l.%s��'�'�r� 3� �.x*���.�s 5- ^� f •'-��� �� *3-rte-• <br /> } <br /> December 18, 1991 <br /> Former Unocal Station 2859, Stockton, California <br /> Results of laboratory analyses indicated TPHg was detected in the samples collected from <br /> wells 1NTW-4 and NIW-5 at concentrations of 90 parts per billion (ppb) and 210 ppb, <br /> respectively. BTEX compounds were detected in the water samples collected from wells <br /> MW-4 and MW-5, with benzene detected at concentrations of 5.6 ppb in the sample <br /> collected from MW-5 and 0.5 ppb in the sample collected From IMW-4. <br /> WORK IN PROGRESS <br /> A work plan has been prepared and submitted to San Joaquin County Public Heal, <br /> Services,Environmental Health Division,for drilling an additional downgradient monitoring <br /> well, drilling vapor-extraction wells onsite. and conducting a vapor-extraction test. The <br /> vapor-extraction test will be performed at Unocal's request to evaluate whether remediation <br /> of soil using vapor-extraction is feasible. Unocal has requested authorization from the City <br /> of Stockton Public Works Department to install an additional groundwater monitoring well <br /> downgradierlt from wells IMW-4 and MW-5. <br /> CONCLUSIONS AND RECOi1I1VIENDATIONS <br /> Analytical results indicated the benzene concentration in the water sample collected from <br /> well MW-5 was above the Maximum Contaminant Level for drinking water in Title 22, <br /> k" California Code of Regulations, Section 64444.5. Based on this result, we recommend <br /> continuing quarterly monitoring. We have scheduled the next sampling for the first week <br /> of January 1992. <br /> We recommend a copy of this report be forwarded to lois. Diane Hinson of the San Joaquin <br /> Local Health District, P.O. Box 2009, Stockton, California 95201, and Ms. Elizabeth A. <br /> Thayer of the California Regional Water Quality Controi Board, Central Valley Region, <br /> 3443 Routier Road, Sacramento. California 95827-3098. <br /> 3801:7 3 <br /> y,r <br /> Ill:A 111 <br /> i <br />