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' Aquifer Testing Work Plan • • FormerBro Facility 1905 Northrth Broadway Avenue - ' Stockton,California Sierra-Pacific Project No. 94-055.05 ' Western continues to formulate and distribute bulk fertilizer products at the site. Pesticides are still sold at and distributed from the facility in sealed containers. In early 1994, in response to the RWQCB ' request for an environmental investigation,Unocal authorized Sierra-Pacific Groundwater Consultants, Inc.now dba Sierra-Pacific Group(Sierra-Pacific)to conduct both ground-water and soils investigations ' at the Broadway Avenue site (Figure 3). Much of the work done at the site to date has been accomplished in accordance with contractual arrangements between Unocal and CPS/Western. ' Hydrogeologic and analytical test data gathered since 1993 indicate that shallow ground water beneath the site, and down-gradient from the site,contains nitrates, 1,2-DCP,and other pesticides. From about ' 1965 to about 1985, PureGro and Brea placed fertilizer and diluted pesticide rinsates into shallow evaporation ponds at the site. The data indicate that the groundwater contaminants are derived primarily ' from contaminated soils located beneath the former unlined evaporation pond in the northwest corner of the subject site (Figure 3). The old evaporation ponds are no longer used. Engineered HDPE/asphalt liners were installed over each ' of the contaminated pond areas in 1996 to minimize further infiltration of contaminants to the ground water. 1 2.0 PURPOSE A program for determination of shallow aquifer characteristics has been developed.The aquifer testing program will provide data on the storage capacity and pumping characteristics ofthe stratified sediments that comprise the host media for the impacted ground water. Hydrogeologic system modeling and fate ' and transport analysis will be based in part on the information obtained from the aquifer testing program. ' This information will then be utilized in the design of both pilot-scale and full-scale remediation systems at the site. ' SIERRA-PACIFIC GROUP 2