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Messers. Freitas and Gilton - 2 - 14 December 2005 <br /> o The type of residences and how many residences are planned in the development. How many <br /> bedrooms will the typical house have? <br /> o The types of commercial businesses that are envisioned at the development, whether they <br /> draw large numbers of people on weekends, and how wastewater flow was estimated. <br /> • It is unclear if Oakwood Lake will continue to be pumped to artificially lower the lake level. <br /> Please address the following issues regarding the pond and groundwater: <br /> o Please describe the need for continued pumping. If pumping will not continue, how will that <br /> affect the groundwater elevations at the percolation basin and the land application area? <br /> What will the depth of groundwater be below the percolation ponds and land application <br /> area? If pumping will continue, will it be at rates that are likely to change the groundwater <br /> elevation? <br /> • The groundwater data is not presented in a way that can be verified by the reader. Please address <br /> the following issues: <br /> o The Condor report states the lake pumping will control groundwater flow direction at the <br /> percolation ponds. However, review of the groundwater elevations in Figure 1 (which is <br /> presented in the Holdredge and Kull report) indicates groundwater flow is not directly <br /> towards the lake. Please describe the current understanding of groundwater conditions. <br /> o The Condor statement that groundwater below the percolation ponds will take two-years to <br /> migrate to the lake is not supported. Please present the information used in calculations. <br /> o The discussion of constituents that may degrade groundwater discounts some parameters with <br /> the statement that they are not a threat to human health. This approach is not consistent with <br /> the Antidegradation Policy (State Board Resolution 68-16) and therefore that discussion must <br /> be revised. <br /> • Please clarify which equipment from the existing wastewater treatment system is proposed for <br /> continued use and what will be new construction. Will aeration devices be used in the percolation <br /> ponds? <br /> • The details of how the wastewater system will be constructed and operated are not provided. Staff <br /> are concerned that the infiltration analysis is overestimating the amount of wastewater that will be <br /> able to percolate. Please address the following issues: <br /> o It is not clear whether the percolation pond area will be used as percolation ponds or as rapid <br /> infiltration basins. The Holdrege and Kull report recommends the area be dried and the soil <br /> disced, although no description of where wastewater would be discharged during the time <br /> required for soil drying is provided. If the percolation pond will be used as rapid infiltration <br /> basins,the safety factor employed in the calculations is not suitably conservative. The EPA <br /> Design Manual, Land Treatment of Municipal Wastewater recommends a safety factor of <br /> approximately 0.05 (mathematically, the safety factor used in the Holdredge and Kull report <br /> was 0.20). <br /> o The infiltration capacity evaluation provided does not address the low permeability material at <br /> a depth of five feet (described as low plasticity clay), which is described in the Holdrege and <br /> Kull report. Staff notes that infiltration ponds in San Joaquin County constructed over similar <br /> W:\$\aff\ObrienlT5 jl Joaquin\Oakwood LakdFrcitas 1 Dec 05.doc <br />