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Revised November 4, 2020 BGG Job No. G164.01 encountered were classified and logged,and approximately 2-inches of clean pea gravel was placed in the bottom of the boring. About 18-inches (vertically) of water was poured into the borehole and allowed to saturate overnight. Upon returning to the test hole on August 17,2020, it was observed that no water remained in the hole. Percolation testing was then performed by pouring approximately 6-to 8-inches of water into the test hole and measuring the drop in the water level over 30-minute intervals for a total period of 4 hours.The results of the percolation test are contained in Appendix A. Percolation Test Results A rate of 18.5 minutes/inch was recorded for the nursery's septic system and leach field. SJCEHD defines a shallow percolation test hole as having a depth between 36 and 42 inches; a satisfactory percolation rate for a shallow test is one resulting in a water level drop greater than or equal to 1 minute per inch(min/in)but less than or equal to 60 min/in. For the site to utilize a standard septic system, one percolation test must demonstrate a satisfactory percolation rate within the proposed septic system disposal field. Discussion of Percolation Test Results The soils within the proposed septic system leach field area have demonstrated a satisfactory percolation rate for the use of a standard septic system in accordance with the requirements of the SJC EHD. Due to the percolation rate recorded,the SJC EHD will require a 20-foot separation from the bottom of the dispersal system to ground water. Groundwater is anticipated to be encountered more than 40 feet bgs at the site; as such, modifications to standard septic systems should not be required. Discussion of Septic System Sizing Septic system construction utilizing leach lines should follow the San Joaquin County On-Site Wastewater Treatment Systems Standards (2017)where applicable. NITRATE LOADING STUDY Due to concerns of nitrate leaching into groundwater from septic systems,a nitrate loading analysis was required by the San Joaquin County Environmental Health Department(SJC EHD)for approval of the proposed Zinc House Winery septic system. The intent of the study is to estimate the potential concentration of percolating effluent produced by the proposed septic system for an extended period. Where percolating effluent leaches into the ground, groundwater quality may be impacted to a degree, should the effluent reach the groundwater table. The method utilized for the nitrate loading analysis is based on a simple and convenient mass balance formula, discussed in a published article by Hantzsche and Finnemore (1992),predicting groundwater Nitrate-Nitrogen impacts. The H&F equation is a conservative approximation of groundwater nitrate-nitrogen concentration resulting from the combined effect of on-site sewage disposal systems and rainfall precipitation. The H&F equation and method are appropriate for estimating longterm effects on groundwater quality;it is not intended for use in predicting seasonal fluctuations (H&F, 1992). The method considers the BAEZ GEOTECHNICAL GROUP Soil Suitability Study and Nitrate Loading Study-I Hsin Orchids Page