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Soil Suitability and Nitrate Loading Evaluation Page 5 - U of P-Golf Practice Facility Expansion 6301 West Eight Mile Road Stockton, California May 13, 2019 CTE Job#25-0711G Nb = Background nitrate nitrogen concentration of rainfall recharge at the water table is assumed to be on the order of 0.5 mg/l (Technical Memorandum, Hydrologic and Soil Investigation for the Chico Urban Area by Dames and Moore, April 1996). Our nitrate calculation is as follows: using Nc= [I(N,,)(1-D) +R(Nb)] /(I+R) Nc= [0.37(70)(1.0-0.20) + 11.2 (0.5)] /(0.37+11.2) =6.35 mg/1 as N l The calculated nitrate (6.35 mg/L as N) for groundwater Nitrate-Nitrogen Impacts is below the State drinking water standard of 10 mg/L for nitrogen(N). 10.0 CONCLUSIONS A suitable soil condition for septic percolation tests is defined as a stratum capable of percolating water at a rate of 60 minutes per inch (min/inch) at a depth of up to 3.5 feet below existing site grade or 30 min/inch for deeper tests. CTE's percolation results for - this project were "No Take". Based on these results, it is our professional opinion that a conventional septic tank/leach trench sewage disposal system designed per SJEHD criteria will not adequately serve the proposed building and an engineered system will be necessary at the site. As stated in Section 9.0 above, CTE estimates that the potential nitrate-nitrogen (N) concentration in groundwater resulting from the new leach field should be below the state standard of 10 mg/L. 11.0 LIMITATIONS The field evaluation, laboratory testing and analysis presented in this report have been conducted according to current practice and the standard of care exercised by reputable consultants performing similar tasks in this area. No other warranty, expressed or implied, is made regarding the conclusions, recommendations and opinions expressed in this report. Variations may exist and conditions not observed or described in this report may be encountered during construction. Our conclusions and recommendations are based on the observed conditions. If conditions different from those described in this report are encountered, our office should be notified and additional recommendations, if required, will be provided upon request. We appreciate this opportunity to be of service on this project. If you have any questions regarding this report, please do not hesitate to contact the undersigned. This report assumes CTE will observe construction activities associated with placing the septic system. Our recommendations may be reevaluated based upon exposed conditions.