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Greg Burns - 2 - 6 April 2005 1. Please reconsider the location of the monitoring wells. The well locations presented on Figure 3 will be acceptable if the groundwater flow direction is to the southwest; however, if the flow direction is more to the west or north than anticipated, the wells will not be located downgradient of the land application areas and additional wells will be required. Consider locating downgradient wells within the land application areas. 2. As stated in the Regional Board's 16 February 2005 Conditional Approval letter, because stormwater/wastewater mixtures can be discharged to the stormwater pond as described in Finding No. 9 of the Waste Discharge Requirements (WDRs), groundwater monitoring must be performed at the pond. The 10 March 2005 Workplan does not address the issue. If the wastewater system has been upgraded to prevent such discharges, the additional groundwater monitoring well may not be needed. Please provide information on the stormwater pond or add a groundwater monitoring well at the stormwater pond. 3. Many of the well construction issues raised in the 16 February 2005 Conditional Approval letter have not been addressed. The following issues must be addressed: • The workplan states that the borings will be drilled to 35 feet but only 30 feet of well casing will be installed. Please clarify the well construction details and provide a well construction diagram showing anticipated construction depths and well materials. • Please surge the sand pack prior to installation of the bentonite transition seal if conditions in the borehole allow. • The annular seal is described as "neat bentonite grout." Use of pure bentonite to seal the annular space is not acceptable due to the depth to groundwater and the possibility that a bentonite annular seal will dry out and crack. Neat cement or cement/bentonite slurry (with a maximum of five-percent by weight of bentonite) is acceptable. Please describe how the annular seal will be placed. • The workplan does not specify which type of wellhead will be used in the construction. In general, stovepipe wellhead construction is preferable to flush wellheads when the wells will be installed in non-paved areas. The use of bollards should be considered if traffic or livestock might damage the wells. The wellhead shall be set in a concrete pad at the surface that is sloped to drain water away from the well casing. • Section 4.0 of the workplan states that wells will be constructed consistent with"common practice in the environmental industry and the San Joaquin Environmental Health Department guidelines for well construction." All well construction must be consistent with the California Well Standards 74-90 and the San Joaquin County Well Standards ordinance. The workplan should adequately describe the installation so that a reader can determine that the well installation will be consistent with regulations. W:ISia=bricnTSanloNuinVenie's GroVeBH 5Apr 05.doc