SITE INFORMATION AND CORRESPONDENCE

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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2002-0148 - 10- MUSCO FAMILY OLIVE COMPANY AND THE STUDLEY COMPANY WASTEWATER TREATMENT AND LAND DISPOSAL FACILITY SAN JOAQUIN COUNTY Well TOC Elev. Screen Depth TDS Cl Na NO3 as N ft. msl (ft. bgs) (mg/L) (mg/L) (=g L) (mg/L) W-2 (1985)(S) 261.93 20-50 740 107 265 5 MW-3(S) 308.75 9.5-19.5 2,900 476 780 0.9 MW-5(S) 292.05 25-45 2,200 605 580 ND MW-6(S) 329.39 40-55 2,600 830 780 16 MW-10(S) 259.68 11.5-21.5 2,600 1,300 800 22.5 MW-11(S) 273.68 35-40 2,000 645 625 15.9 MW-13(S) 372.00 10-25 2,950 1,450 790 41.5 MW-4(D) 333.72 234.5-249.5 1,200 151 340 3.6 MW-7(D) 266.00 154.5-169.5 2,350 485 540 5.9 MW-8(D) 288.56 208.5-228.5 1,300 200 285 9.6 MW-9(D) 291.83 126.5-141.5 Well was dry MW-12(D) 269.25 85-100 2,200 555 535 24 EC denotes electrical conductivity. TDS denotes total dissolved solids. CI denotes chloride. Na denotes sodium NO3 as N denotes nitrate as nitrogen. ND denotes not detected. Well MW-2(1985)is an existing well installed in 1985. Depth zone indicated in well name(S)indicates shallow,(D)indicates deep. 45. The depth to groundwater is highly variable across the site and in some areas exists in confined conditions. Two saturated zones have been identified to date: a shallow water table zone and a deeper confined zone. At this time it is unclear if shallow zones in the upland areas are hydraulically connected to water table zones in lowland areas. The possibility of existence of a water table zone in the northern areas of the site (where the confined zone is identified) has not been fully evaluated. Depth to groundwater vaned from 14 to 175 feet below ground surface. Land surface elevations vary from 259 to 443 feet above mean sea level. 46. Groundwater flow directions generally mimic the topography. Overall the flow direction is to the northeast, however, topographic variations can significantly change the local flow direction. 47. While the Discharger has shown that local groundwater is of generally poor quality, the on site monitoring wells show that the Discharger's activities may have impacted the underlying groundwater. The Groundwater Monitoring Well Installation Report identified the chemistry of the groundwater in the shallow and deep zones as distinctly different, with shallow zones tending to have higher concentrations of sodium, chloride, and total dissolved solids. 48. The RWD clearly shows that the Discharger intends to apply significantly more salt than will be taken up by the crops. In order to determine whether the Musco's proposed project is protective of the underlying groundwater, specific background groundwater values for various constituents must be determined. Other than supplying the above data, the Discharger has not proposed a method or rationale for calculating background concentrations. In the tentative WDRs, staff proposed background concentrations using monitoring wells MW-1 and MW-8. The Discharger has provided comments as to why the use of these two wells is inappropriate, and staff agree that further refinement of the site-specific groundwater quality is necessary. As described in the Information Sheet, staff have fully reviewed the above data sources, and have determined that