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â–  <br /> February 27, 2020 Irerra <br /> n <br /> Ms. Cynthia Acosta <br /> Acosta Construction <br /> PO Box 947 <br /> Woodbridge, CA 95220 <br /> Re: Soil Suitability / Nitrate Loading Study -Addendum <br /> Whitlow Property, APN: 063-040-23 <br /> 11065 N. Alpine Road RECEWD <br /> Stockton, San Joaquin County, California <br /> Terracon Project No. NA197078 FEB 2 8 <br /> ENVIRONMENTAL NTH <br /> Dear Ms. Acosta, DEPARTMENT <br /> This letter is in response to the San Joaquin Environmental Health Department (EHD) letter for <br /> the Soil Suitability /Nitrate Loading Study (SSNLS), 11065 Alpine Road, Stockton, CA APN 063- <br /> 043-23, SR0081473 dated February 13, 2020 and Memorandum dated February 12, 2020 <br /> prepared by Questa Engineering Corp. (Questa). Per the request of the EHD, Questa performed <br /> a third party review of Terracon's SSNLS dated November 20. 2019 for the subject property. The <br /> Questa Memorandum recommended Terracon reduce the site wastewater flow based on Zang <br /> terrn average discharge of wastewater. Questa additionally recommended Terracon adjust <br /> rainfall recharge calculations based on reduced evapotranspiration rates for residential <br /> landscapes. <br /> Based on a February 27T 2020 telephone conversation with Ms. Kasey Foley of the EHD, Terracon <br /> revised the long term average discharge of waste water for the nitrate loading calculation from <br /> 560 gallons per day to 250 gallons per day for a 4 bedroom residence. Ms. Foley recommended <br /> 100 gallons for the first bedroom and 50 gallons for each additional bedroom. Per the <br /> recommendation of Questa, Terracon adjusted the estimate of net rainfall recharge from 4.49 <br /> inches per year to 6.80 inches per year. The following table presents a summary of the nitrate <br /> loading calculation for the site based on the reduced long term average discharge and increased <br /> rainfall recharge. <br /> Summary of Nitrate Mass Balance Equation - Revised. <br /> Result Average Effluent Leachfield Net Rainfall <br /> Land Use (Nc)" Acres pally Flow Concentration Denitrificatlon Recharge <br /> (mglL-N) (A) (Q)(gpo) ( (mNw) (d) (R)(inlyear) <br /> Residence 8.0 1.50 250 45 35% 6.80 <br /> ;Nitrate as N Total 8.0 <br /> 'Maximum contaminant level(MCL)for nitrate in drinking water is 10 mg&-N. <br /> Terracon Consultants Inc. 902 Industrial way Lodi. CA 95240-31W <br /> P 209-367.3701 P 209.333.8303 terracarâ–º.corn <br />