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t h4 KLEINEELDER 1 3 BACKGROUND DSS proposes to mine gravel at their Tracy facility, and is limited to mining above the groundwater table. Based upon a letter from PHS/EHD, DSS was requested to submit a groundwater-monitoring plan for the proposed gravel pit area for their review and approval. According to the PHS/EHD letter "The plan shall address overdraft, perched water, flow patterns, and possible changes to water quality." Kleinfelder contacted Mr. Ray Borges of the PHS/EHD for additional information. Mr. Borges indicated that three deep production/irrigation wells at and in the near vicinity of the DSS gravel pit could be used to assess groundwater elevation, flow and gradient and groundwater quality to comply with PHS/EHD request. Mr. Borges noted some concern over the validity of the proposed groundwater sounding data based on potential influence by the Delta Mendota Canal. The closest well (Well No. 3/Plate 1), according to Mr. Chad Dessert, of DSS Company, reportedly is about 350 feet east of the canal and the uppermost-screened interval is at a depth of approximately 240 feet. Static water level of groundwater was reported by DSS to be at an approximate depth of 145 feet below existing ground surface. Kleinfelder understands the Delta Mendota Canal is lined with concrete, but that t leakage from the canal may occur. However based upon the distance of the nearest well to the canal and the screened interval depth, it is Kleinfelder's opinion that the effects of leakage from the canal would not significantly affect the groundwater level in this well and would likely be r negligible if it did. However, future groundwater soundings and resulting flow and gradients should be assessed for any suspected anomalies, which may be caused by leakage from the Delta Mendota Canal. Mr. Borges from the PHS/EHD has additionally requested that the deep wells be monitored for general minerals on an annual basis. k The San Joaquin County Community Development Department Development Services Division i (CDD) has requested that the two shallow monitoring wells be installed to monitor potential perched water and/or seepage between the Delta Mendota Canal and a proposed settling basin located near the eastern border of the subject site. Quarterly groundwater-level monitoring of these two wells and annual reporting has been requested. Mr. Chad Dessert has requested that a N single domestic well in the vicinity of the site also be sampled. Based upon this request Kleinfelder submitted a workplan to DSS titled "Second Revised Proposal/Cost Estimate, Monitoring Well Installation and Groundwater Sampling and Analyses, Proposed DSS Gravel Pit (QX-96-1), Koster Road Facility, Tracy, California", dated September 27, 2000 (YPO-212). This report details Kleinfelder's findings based upon this workplan. 20-2245-36.E01/2011 R279 Page 3 of 10 Copyright 2001,Kleinfelder, Inc, March 14,2001 1