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Messrs. Calvin and CrandeP - 2 - 0 1 June 2007 April 2006 Kennedy/Jenks Consultants report titled Groundwater Characterization Report, which states, Total Dissolved Solids "(TDS) concentrations in the offsite groundwater wells north of the River were relatively spatially consistent, with a median of 206 mg/L and a range of 93 to 314 mg/L." Staff notes that the median value reported in the offsite groundwater wells is close to the TDS value reported at CPT-1 (190 mg/L), which we have proposed a potentially appropriate for use as background groundwater quality criteria. In summary, the requirement in the tentative CDO for determination of background groundwater quality was not deleted. • The approach to treating process water to irrigation water quality may not be consistent with the Antidegradation Policy depending on the source of the irrigation water and the land application area loading rate. The 14 May 2007 letter proposes an approach that relies upon use of treated process water that is similar or better quality than irrigation water used in the area, double cropping, and irrigation scheduling to minimize leaching to protect groundwater quality. But the RWD reports land application areas have been taken out of use, the winery is proposing a significant expansion, and flow reductions through water conservation are also proposed. Those activities will result in higher concentrations of waste constituents applied to less land application area acreage. That is likely to cause increased land application area loading of Fixed Dissolved Solids (FDS). However, the use of unsaturated soil to store FDS is not a long term viable solution to the wastewater issue. In addition, considering the impact to groundwater quality that has already been observed, staff question how much attenuation capacity still exists in the unsaturated zone. The crop uptake reference (Horneck, 2001) discussed in the 14 May 2007 letter was reviewed upon your transmission of the document and it consisted of a Powerpoint presentation. The document does not contain any data to support the crop uptake values described. Therefore, staff cannot rely upon the document in revising the tentative CDO. The tentative CDO has been revised to require a technical study to establish what the site- specific crop uptake rate potential is. That information can be used in the RWD, which is also required by the tentative CDO. • The 14 May 2007 letter addresses the existing wastewater ponds, describes that they are within the 100-year floodplain and requests no action on the ponds until results from a Department of Water Resources (DWR) floodplain report is completed in 2012; after that time, some action would be proposed. But the letter also states, 'The proposed treatment system will likely obviate the need to use the existing ponds..." Staff notes that the proposed three phase schedule states the wastewater system improvements will be completed by 15 August 2010. The tentative CDO maintains the three phase schedule as described in the letter and requires a contingency plan to handle wastewater in the event the Mokelumne River inundates the wastewater ponds until the improvements are complete in August 2010. • Regarding the number of technical documents required by the tentative CDO transmitted on 16 March 2007, staff has reduced the number of deliverables by combining the tasks and grouping them into the phases described in the comment letter. While staff is available to meet to discuss the project progress, communications must be in written form so that it can be documented in the project file. The request for the Executive Officer to W:\SialPObnen➢San Joaquin i Mondav\CDD May OTCalvia 30 May 07 dm