SITE INFORMATION AND CORRESPONDENCE

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Sutton and Teed-Bose - 2 - 19 April 2004 5. Please clarify Section 4.3 to clearly indicate that nested wells are not proposed for this phase of work. 6. Section 4.3 describes criteria for placing the wells based on the presence of sand in the soil borings. Because the soil sampling methodology is not described in the workplan, it is impossible to evaluate the proposal. The workplan does not indicate what would occur if no sand were logged in the boring. Please clarify this section of the workplan. 7. Please include an example of a geologic log that will be provided in the well installation report. The statement in Section 4.3, "Geologic logs of the boring will be made in accordance with common practice at the time the work is performed," is not descriptive enough for staff to approve the work. 8. The wells are designed with only six-inches of sand above the screen interval. Slightly more sand above the screen interval may reduce the possibility of bentonite entering the well if the sand settles during development. Staff strongly recommends the filter pack be surged prior to placement of the transition material as described in Section 13.10.8 of San Joaquin County Environmental Health's Well Standards ordinance. 9. Section 4.3 does not adequately describe how the annular seal will be placed and what the materials will be. Please include well construction details for both shallow and deep wells. Because the area is characterized by hot and dry summers, staff is concerned that bentonite may dry and crack in the summer months. Please maximize the use of neat cement/bentonite in the annular seal; one to two- feet of bentonite as a transition seal is generally adequate. The well construction details shall also depict the use of concrete in the wellheads and stainless steel screws to secure slip caps if they are used on the bottom of the well. 10. Please correct the description of the concrete pedestals in Section 4.3. 11. Staff agrees with Section 4.4, which recommends surveying the existing on-site wells. All wells shall be surveyed to allow determination of groundwater flow directions. 12. Section 5.1 describes the agricultural drain monitoring locations and Figure 1 presents the sample locations. Please add a monitoring location for each of the drains. Because much of the drain may be dry, selection of a sampling point for each drain can be established based on a description such as, "The furthest upstream a sample can be collected in Drain No. _,but no further upstream than_" This approach will require identifying each drain and the area from which a sample can be collected. Please submit the revised workplan in accordance with your schedule. However,please note that the WDRs require one year of monthly sampling prior to using new land application areas, and therefore the revised workplan must be submitted at least 15 months prior to your plan to use the new ponds and/or land application areas. Failure to adequately characterize the groundwater quality at the proposed ponds and/or land application areas may result in delays in Regional Board approval to use the improvements. Mountain House CSD and Trimark Communities shall submit quarterly monitoring reports that tabulate all groundwater data collected to date during the characterization phase. The monitoring reports shall include all the groundwater data collected, including data collected at the wastewater storage ponds and W%IAM ai MJw uinV nWin Hnw�ulWn c19 Apr W.&c