Laserfiche WebLink
A R R — 22h -9Z T H U 9 1 7 C O N D O R 1=— ART " TEC T U R L OCK <br /> FRIM UNOCAL CEFT-HOATN • 03.0�, I 5&t-34 P. 2 <br /> ecology and environment, inc. <br /> tee SPEAR STAEET, SAN FRANCISCO, CALIFORNIA 94106, TEL 4161717•2211 <br /> Imemttbnil Spodelhq h the Envhpnm.nt <br /> l4gttORANDUK <br /> 7O1 Carolyn Douglas, U.S. EPA, $AM <br /> FROMI Faul Cort, Ecology and Environment, Inc. <br /> DATES February 23, 1993 <br /> SUBJE M Brea Agricultural Services #2 <br /> cc: Jim James, Ecology and Environment, inc. <br /> central File <br /> Ecology and Environment, Inc. •(B 3 B) has completed review of the <br /> Work Plan for Soil and Groundwater 3nvesti ation (January 22, 1993) <br /> prepare y on or art Tec no og es, inc. Condor), for the <br /> PureGro/Brea facility in Stockton, California. The Work Plan was <br /> prepared in response to a request by the Central Valley Regional Water <br /> Quality control Board to investigate the source of 1,2-dichloropropane <br /> and nitrogen in the soils and groundwater at the site. The investigation <br /> at the PureGro/Brea facility is being overseen by Unocal. <br /> The purpose of E b E's review was to determine whether the Work Flan <br /> will meet EM'S objectives and to suggest possible changes to the Work <br /> Plan to facilitate a coordinated sampling effort between Unocal and EPA. <br /> To the extent that changes cannot be made to the Work Plan, separate <br /> sampling may need to be done to meet EPA needs. <br /> The current Work Plan includes installing three monitoring wells at <br /> the PureGro/Brea facility. During drilling of the boreholes, soil <br /> samples will be collected at 5-font Intervals using a split-spoon sampler <br /> fitted with three 6-inch-long brass liners, Condor will dispose the <br /> first (uppermost) liner, use the second for geological lagging, and send <br /> the third to a laboratory for analysis, After the monitoring wells have <br /> been developed, Condor will collect groundwater samples for analysis and <br /> periodically measure groundwater depths to estimate the local groundwater <br /> gradient. <br /> E It E proposes the following modifications to the Work Plan to <br /> achieve EPA's objectives: (1) move the proposed locations of the <br /> vonitoring wells to target areas of known or suspected contamination and <br /> Incorporate more of the facility and (2) provide EPA with two 3-inch <br /> brass liners of soil collected at 5-foot intervals. These changes are <br /> discussed in more detail below. E b E also proposes that EPA be allowed <br /> pc/brea2/memo <br /> racvc4tl pepi� <br />