ARCHIVED REPORTS_SECOND HALF AND ANNUAL 2010 GW MONITORING RPT

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Diamond Pet Food Processors of Ripon California LLC Jarman'28,2011 Combined Annual and Fourth-Ouarter 2010 Groundwater Monitoring Report Page 8 of 8 The City is currently under directive from the CVRWQCB to evaluate the impacts of effluent disposal on groundwater quality. Nestles Nestles USA formerly operated an instant coffee and tea processing plant, located approximately 2,000 feet north of the DP site, from 1948 through 1986. Solvents used in the decaffeination process, and their daughter products (trichloroethene, dichloroethene, and vinyl chloride) have impacted soils at the site and groundwater throughout the Ripon area. Nestles' consultant, Environmental Cost Management, currently operates two groundwater-treatment systems in the area to remediate the contaminant plumes. The plumes have impacted the upper and intermediate aquifers along the northern and western portions of the DP site. Based on the distance of the remediation system's extraction wells from DP, the volume of water treated by the system (<500 gpm), and the relatively high permeability of the aquifer, it is unlikely that the extraction system would influence the hydraulic gradient in DP wells. The capture zone of the extraction wells, however, may extend beneath the DP site. An increase in TDS levels in the treatment system influent would indicate that higher TDS water originating at DP is being captured by the system. Hydrogeologic setting Geology and hydrogeology of the site and vicinity have been described in detail in previous reports.K Briefly, the Millis located in the East San Joaquin Groundwater Basin and is underlain by a sequence of Tertiary- and Quaternary-aged continental deposits of the Tulare Formation. These deposits consist of interbedded sands/gravels and silts/clays or mixtures thereof. Four distinct aquifers or zones have been identified beneath the site and have been designated by L&A as the semiperched, upper, intermediate, and lower zones. The semiperched zone is unconfined and occurs from approximately 35 to 60 feet below ground surface (bgs). All other zones are semiconfined to confined. The upper zone occurs from approximately 85 to 110 feet bgs, the intermediate zone from 140 to 225 feet bgs, and the lower zone from 240 to greater than 300 feet bgs. Permeability in the aquifer zones has been estimated at approximately 525 gpd/ft2; permeability in the confining layers has been estimated at 3.5 gpd/ft2.9 Groundwater movement in the semiperched and upper semiconfined zones in the vicinity of Ripon is generally to the west.10 North of Ripon, groundwater moves to the north. Southwest of Ripon, on the southwest side of the San Joaquin River, groundwater also moves to the north, towards the river. Summary of work performed All work was performed in accordance with DP's Sampling and Analysis Plan (Attachment D). L&A,May 5, 1992,Impacts on Receiving Waters from Discharge at the Simpson Paper Company Facility, Ripon, Califarnia. Ibid., P.27. 10Ibid., Fig. 3. 10107.01 Task 1 Lawrence&Associates M-ICLIENTSIDiaoumd Pet Foods1070107.01-Grnttndwater blwtitoringl Gromtdwater Alonitoring1207012nd Ha1f30101annual-2nd Half 2010 repomdoc