SITE INFORMATION AND CORRESPONDENCE

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Mr. Allen Fetters - 3 - 14 December 2006 Each of the deep monitoring wells will be installed within a conductor casing which will be placed to a depth of 145 feet. Work Plan Comments When completed, the monitoring well data obtained through implementation of this Work Plan will provide additional valuable groundwater data relating to upgradient nitrogen concentrations in shallow and deep groundwater, and will provide a measure of nitrogen contributions to municipal well No. 12 that are not attributable to Ripon Farm Service. It does not, however, address the extent that Ripon Farm Service contributed nitrogen to groundwater, nor does it address the extent, if any, that Ripon Farm Service has contributed nitrogen to municipal well No. 12. Given that it took three months from the preparation date of this work plan to the time it was approved for delivery to Regional Water Board staff, it will likely create enormous additional delays if Regional Water Board staff reauest the site-specific delineation work in this particular work plan. Therefore, Ripon Farm Service needs to provide a follow-up work plan that continues the subsurface investigation work to identify the lateral and vertical extent of nitrate and ammonium in soil and groundwater on-site. This work plan should at the minimum include the following: • Soil and groundwater samples obtained at multiple depth intervals to ascertain whether these pollutants have traveled to deeper zones. • A strategy to determine whether the nitrate observed in MW-101 is from on-site or off-site sources. • A means to identify if there are additional source areas on-site. • A process to identify and repair breaches in the containment and stormwater collection system • A procedure to determine to what extent there is interconnectivity between the shallow and deeper water-bearing zones. • A means to estimate what portion of the nitrate observed in municipal well W-12, if any, might be attributed to Ripon Farm Service. The conductor casings for the deep wells are proposed to be installed using either cable tool or mud rotary equipment, and the well casing will be installed through the conductor casing using a hollow stem auger. As with many well installations, in spite of substantial purging, the first water samples often are not as representative of groundwater quality as subsequent samples. Ripon Farm Service may want to consider obtaining several samples spaced a week or so apart, particularly from the deep wells. Ripon Farm Service proposes to use low-flow sampling procedures to obtain groundwater samples from the shallow and deep monitoring wells. The on-site monitoring wells are currently sampled with low-flow devices. To the extent practicable, similar sampling procedures and sampling dates should be used for off-site and on-site wells in order to equate off-site well data with on-site well data.