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W wzlar� ?69wd�- -M d July 20, 2020 FOR: San Joaquin County Environmental Health Department Mr. Michael Kith,REHS, Program Manager 1868 Hazelton Ave. Stockton, CA 95205 PROJECT: Mr. Rafael Navarro 14499 East Collier Road Acampo, California 95220 APN: 021-030-39, SR0082246 SUBJECT: Response to the EHD Comments regarding the Onsite Wastewater Treatment System (OWTS) Design Report for the referenced project. In the referenced EHD document, Item 2,Mr. Kith states "the proposed septic system design appears to have a standard septic tank and wastewater disposal field. The proposed septic system design does not propose a method to mitigate the percolation rate of 250 minutes/inch." This is incorrect. Although the disposal field is what is typically required for the two bedroom onsite modular homes, the septic tank size has been increased. In keeping with Section 7.1 of the San Joaquin County OWTS Standards, the following information addresses "the method to mitigate the percolation rate of 250 min/in"and referenced in the Subsections of Section 7.1 below: Section 7.1.1. A scaled plot plan was submitted for this project. Section 7.1.2. The total capacity of the system is referenced in the last paragraph of Page 3 in the Conclusions Section of my Report at 90 gpd (ADF). The organic load is conventional residential and as stated in the first paragraph on Page 3, fats,oils and grease (FOG) and all food products from the kitchens must be handled as solid wastes to substantially lower organic loading. As stated, I increased the septic tank size from the required 1,200 gallons to 1,600 gallons. This is a 33% increase in capacity. In the second paragraph on Page 3, this 33% increase in tank size will increase the hydraulic residence time of the influent, and decrease the raw wastewater (influent)nitrogen concentrations by at least 20%. In addition,the 33%increase in tank size will significantly increase the buffering capacity of the tank between influent inflow and effluent outflows. As stated in Septic Systems Handbook by Kaplan: "The [septic] tank buffers sudden incoming flows and releases the clarified sewage slowly and continuously for up to roughly 20 minutes after the incoming flows stop." I have witnessed this many times and the septic system contractors I work with have witnessed it hundreds of times. As stated by highly respected wastewater engineer T. R. Bounds, PE in his paper Design and Performance of Septic Tanks,he states "The septic tank may be the single most important component used in onsite treatment and collection alternative." I agree with this statement and is the reason I increased the tank size 33%. Page 1 of 2 P.O. Box 3794. ❑ Turlock,CA 95381 ❑ 209.402.1652 ❑ ddchesngyCa charter.net