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A shallow percolation test is defined by the EHD as being between 36 and 42 inches in depth; a satisfactory percolation rate for a shallow test is less than or equal to 66 minutes per inch drop. A deep percolation test is defined as being between 3.5 and 25 feet in depth; a satisfactory percolation rate for a deep test is 30 min/in or less. One percolation test must demonstrate a satisfactory percolation rate within the proposed septic system disposal field of each parcel to utilize a standard septic system. Details of the percolation tests are summarized in the table below. Table 3. Sum ag of Percolation Tests. { Test No., Percolation Test Percolation Rate Comments I Date Tested Depth (ft.) (minutes/Inch) Test Duration (see notes) kP-1 (shallow) 3.30 1.1 1-hr Satisfactory ry pert rate Note: A satisfactory percolation rate for a"shallow"test is less than or equal to 60 minutes per inch. A satisfactory percolation rate for a"deep"test is less than or equal to 30 minutes per inch. 1.6.7 Discussion of Percolation Test Results The soils within the sewage disposal area of the site has demonstrated a satisfactory percolation rate in accordance with the requirements of the EHD for the use of a standard septic system. 1.6.8 Discussion of Septic System Sizing Septic system construction should follow the San Joaquin County On-Site Wastewater Disposal Standards where applicable. 2.0 NITRATE LOADING STUDY Because of concern regarding nitrate leaching into ground water from septic systems, a nitrate loading analysis was required by the EHD for the proposed development to measure the potential concentration of percolating effluent and rain fall over the long term. Where percolating effluent leaches into the ground, ground water quality may be impacted to some degree should the effluent reach ground water. The method utilized for the nitrate loading analysis is based on a simple mass balance formula, discussed in a published article by Hantzsche and Finnemore (1992), which provides a convenient and simplified method to estimate long-term ground-water nitrate impacts on an area-wide basis. Hantzsche and Finnemore found that over a long period of time, water quality in the upper saturated ground-water zone closely approximates the quality of percolating recharge waters. They believe that their method is a good planning tool and provides useful information to planners and local officials but with some real limitations. In their article published in Ground Water, Hantzsche and Finnemore mention that "...the equation ignores dispersion, lateral flow, and mixing with ground water flow from up-gradient areas. These processes would generally i 902 Industrial Way-Lodi,CA 95240.209.367.3701 -Fax 209.369.4228 ©2008 Neil O.Anderson&Associates,Inc