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• tennedy/Jenks Consultants Mr. Tim O'Brien California Regional Water Quality Control Board 25 August 2006 Page 2 CRWQCB comment 2: Section 1.8.1 states, "Surface water was estimated in the Effluent Limit Determination Technical Report to take approximately 50 years to reach groundwater at 55 feet bgs, according to the soil moisture loading model."Staff recognizes the slow nature of groundwater flow, but if the data from the pan lysimeters provided in the 12 August 2004, Effluent Limit Determination Technical Report, is considered, groundwater conditions may worsen considerably as a result of the continued discharge. The pan lysimeters contained percolate with Fixed Dissolved Solids (FDS) concentrations often greater than 3,000 mg/l. If the percolate reaches groundwater, it will result in further groundwater quality degradation. Response: BTQCLC is in the process of implementing changes at the winery to improve the quality of process water discharged to land. BTQCLC recognizes that source control is an effective means of reducing FDS concentrations in its process water and therefore, planned changes at the Facility focus on the reduction and control of constituents contributing to FDS concentrations. More information on the planned changes at the winery can be found in the Interim Response (Kennedy/Jenks, 2005) and in the Engineering Report (Kennedy/Jenks, 2006) dated 26 May 2006. CRWQCB comment 3: Section 1.8.2.3 describes locating offsite sources, but the proposed drilling and sampling locations have already been determined. It may be prudent to identify potential sources first, and then perform sampling to determine if they have impacted groundwater quality. The chemical constituent concentration contour figures are flawed because they contain errors such as inconsistent contour intervals, missed contour lines, and the interpretation ignores groundwater flow direction considerations related to hydrodynamic dispersion. The additional data provided in this investigation may clarify the interpretation. Response: The proposed offsite CPTs east of Wells MW-6 and MW-7 are intended to further characterize groundwater quality and assess whether groundwater is influenced by offsite sources. The proposed approach for further characterizing groundwater includes first placing priority on defining the furthest extent of affected groundwater and then identifying potential offsite influences that could have contributed to the groundwater condition. The approach of identifying offsite sources first and then investigating the underlying groundwater quality is problematic due to long lead times typically required to negotiate permission from property owners to install CPT/Hydropunch or temporary monitoring wells. As the CRWQCB has suggested, additional data will provide clarity in contouring individual constituents within and near the Site. The current contour figures are based on existing data collected from onsite monitoring wells. As discussed above in response to the CRWQCB Comment 1, the Site is elongated in the direction of groundwater flow, which impairs the reconciliation of groundwater gradient with the distribution of constituents reported in groundwater. Groundwater flow direction has been accounted for and the possibility of longitudinal and lateral effects of"mechanical" dispersion (Freeze, 1979) have been accounted for. The unequal contour intervals (missed contour lines) honor the data and were intended to provide succinctness and as best as visually possible mimic the general pattern of constituent transport in groundwater beneath the Site. The CRWQCB's request to construct equal contour intervals will be considered for future presentation of water quality data. g:Vs-groupladminl ob1031030118.08_barrelten106-comspndVtrsVspns_cmmtslcmmts-01.doc