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Soil Suitability/ Nitrate Loading Study Irerracon Schuler Property Tracy, California May 30, 2019 Terracon Project No. NA197026 mitigation options include the use of a carbon source such wood chips. Based on the proposed usage, mitigation may be required by the EHD. 3.0 CONCLUSIONS AND RECOMMENDATIONS In summary, a satisfactory percolation rate of 6.76 minutes per inch was obtained at 3.5 feet bgs. The parcel appears suitable for the use of a standard septic system utilizing shallow leach lines designed for the intended usage. Final septic system construction should follow the San Joaquin County On-Site Wastewater Disposal Standards where applicable. Based on the nitrate loading results, nitrate levels for the current four bedroom residence (17.7 mg/L-N)exceeds the MCL of 10 mg/L-N for nitrate in drinking water when an average two person occupancy is calculated per bedroom. The construction of the proposed three bedroom mobile home (16.5 mg/L-N) is anticipitated to further increase nitrate levels to 34.2 mg/L-N, also above allowable limits for groundwater. Nitrate as N was reported at 15.0 mg/L above the MCL. Groundwater sample GW-2 reported below laboratory reporting limits of 0.010 micrograms per liter(ug/L)for DBCP. The development of an additional residence and septic system may further increase nitrates in groundwater. If the EHD requires mitigation for the project, an advanced water treatment product or carbon source may be considered mitigation options. 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