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California Regional Water Quality Control Board <br /> .• � 0. �� Central Valley Region <br /> Steven T.Butler,Chair r <br /> Winston H. Ilidms Gray Davis <br /> Senetmy jor Sacramento Main Office Governor <br /> Environmental Internet Address: http://i w v.sw b.ca.gov/—nvgcb5 <br /> Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> Phone(916)255-3000-FAX(916)255-3015 <br /> 24 February 2000 <br /> Ms. Miriam L. Barbonio <br /> Chevron Chemical Company LLC <br /> P. O. Box 6047 <br /> San Ramon, CA 94583-0947 <br /> CONDITIONAL APPROVAL OF REMEDIAL ACTION PLAN, KOPPEL STOCKTON <br /> TERMINAL, SAN JOA QUIN COUNTY <br /> I received the February 2000 Remedial Action Plan (RAP)prepared by CH2M Hill for the Koppel <br /> Stockton Terminal. The RAP satisfactorily addresses the remediation strategy for the nitrate and <br /> ammonia products in soil and groundwater for all areas identified for remediation in the Draft <br /> Feasibility Study. <br /> I also received the February 2000 Final Feasibility Study Report(FS) prepared by CH2M Hill. This <br /> document incorporates all of my comments on the Draft FS, and I will respond to this document under <br /> separate cover. <br /> The groundwater monitoring data from both Cal Farm Supply monitoring wells and Koppel monitoring <br /> wells indicate a peculiar groundwater depression on the north side of the Koppel site in spite of water <br /> ponding in this area for signficant periods of the wet season. The measured groundwater elevation could <br /> be different than the actual elevation if one of the flush mount monitoring well casings had been driven <br /> over with heavy equipment during a wet period. Therefore,please resurvey monitoring wells KP-2 and <br /> KP-3 before the second quarter monitoring event. I have also requested that Cal Farm Supply resurvey <br /> its monitoring wells. <br /> The RAP describes the phytoremediation implementation plan for the Koppel Stockton facility including <br /> planting, irrigation, and sampling details. A contractor will provide regular maintenance of the trees <br /> and irrigation system, and CH2M Hill will install two new piezometers. <br /> Remediation of the area immediately adjacent to the warehouse is not included in this RAP, and will be <br /> addressed in future correspondence. <br /> California Environmental Protection Agency <br /> pia Recycled Paper <br />