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Existing Septic Tank Usage in the Vicinity To estimate the septic system usage in the area, our office counted septic systems that exist within approximately one square mile surrounding the property. Air photo imagery from Google Earth was used. Each building cluster on the photo was assumed to have one septic system. Using this method, it is estimated that at least 93 septic systems per square mile are located in the immediate vicinity of the Site. The area surrounding the Site consists primarily of rural residences; a few vineyards and other agricultural properties are present. A small dairy is located approximately one-half mile east of the Site. Septic Permit History in the Vicinity Based on a review of septic permits on file at the San Joaquin County Environmental Health Department for nearby properties, most septic systems in the area utilize leach lines and seepage pits. The septic permits can be found in Appendix 4 of this report. Expected On-Site Maximum Septic Tank Usage Maximum expected usage on the Site would be from the existing and proposed residences. Septic system design should be based on the San Joaquin County On-Site Wastewater Treatment Systems Standards (2017) or other engineering recommendations. Ground Water Information Depth and Gradient Live Oak reviewed ground water elevation information available from the San Joaquin County Flood Control and Water Conservation District to determine the ground water levels near the Site. Data from spring and fall of 2016 were the most recent available from this source. According to an analysis of these maps (Plates 5 and 6), ground water elevation is approximately 30 to 43 feet below mean sea level. Ground water flows down to the northwest at a rate of approximately four feet per mile in the fall map; the rate could not be calculated for the spring map. Given that the ground elevation of the Site is approximately 110 feet above mean sea level, the depth to water below the Site is estimated to be approximately 140 to 153 feet. San Joaquin County experienced its highest recent ground-water levels in 1983 and 1999. Review of ground-water maps for springjof these years (Plates 7 and 8) reveals that depth to water would have been approximately 120 feet. LOGE 1850 Page 3