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Soil Suitability/Nitrate Loading Study Irerracon Soares Property■ Escalon, CA December 13, 2019 ■ Terracon Project No. NA197095 3.0 CONCLUSIONS AND RECOMMENDATIONS The soils encountered on the site generally consisted of sandy silt and sandy clay. A satisfactory percolation rate of 35.71 min/inch (136)at 3.16 feet was obtained in the proposed leach field, west of the proposed residence building pad. Additionally,a satisfactory percolation rate of 50 min/inch (B3) at 3.25 feet bgs was obtained near the southwestern portion of the site. Septic systems in the vicinity consist of septic tanks and leach lines connected to sumps and/or filter beds. Depth to groundwater is anticipated to be greater than 70 feet bgs. Groundwater samples were not collected from the onsite well as the well was not operational at the time of Terracon's field work; therefore, two offsite groundwater samples (GW-1 and GW-2) were collected from the adjoining eastern property domestic well. Nitrate as N was reported at 13 mg/L in groundwater sample GW-1 above the MCL of 10 mg/L-N. Groundwater sample GW-2 reported below laboratory reporting limits for DBCP. The result of the nitrate loading balance (24.2 mg/L-N) indicates that the proposed development may cause a buildup of nitrates in the aquifer above the MCL. In summary,the parcel appears suitable for the proposed development. The septic system design should accommodate peak flows and follow the San Joaquin County OWTS standards where applicable. If the EHD requires mitigation for the project, an advanced water treatment product may be considered a mitigation option. 4.0 LIMITATIONS As indicated, our study takes into account the subject property only with the sewage load applied over the property site area. The study does not take into account surrounding properties and/or lands. 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 groundwater nitrate impacts on an area- wide basis. A more detailed analysis was not requested nor intended. Our professional services were performed, our findings obtained, and our conclusions proposed in accordance with generally accepted engineering principles and practices. This warranty is in lieu of all other warranties either expressed or implied. Test findings and statements of professional opinion do not constitute a guarantee or warranty, expressed or implied. Responsive ■ Resourceful ■ Reliable 17