SR0084295_SSNL - Laserfiche WebLink

Home Browse Search

Quantity and Quality of Domestic Wastewater According to Mrs. Vidauri, a new three-bedroom mobile home will be placed on the Site. The three existing homes have three bedrooms, two bedrooms, and two bedrooms, she indicated. Crites and Tchobanoglous (1998) list a typical flow rate of 50 to 70 gallons per person per day for an individual residence. In the past, San Joaquin County Environmental Health Department has requested that the flow rate be calculated as 140 gallons per bedroom per day to reflect maximum usage. On March 4, 2020, however, Michael Kith of the San Joaquin County Environmental Health Department dictated a new procedure for calculating residential flow, developed in consultation with Norman Hantzsche (author of the 1992 paper discussed previously). He indicated that wastewater flow from a single-family residence should be calculated as 100 gallons per day (gpd) for the first bedroom and 50 gpd for each additional bedroom; additional residences should be calculated in the same manner (personal communication, March 4, 2020). Using this method, each three-bedroom home will contribute 200 gpd, and each two- bedroom home will contribute 150 gpd, for an estimated total maximum daily flow for the Site of 700 gpd. A typical residential concentration of 35 mg/L of nitrate as N was selected for the proposed residence (Crites and Tchobanoglous, 1998). The estimated flow values discussed here should not be used for the design and sizing of the septic system. The design and sizing of the septic system should utilize the San Joaquin County Environmental Health Department On -Site Wastewater Treatment Systems Standards, which incorporates peak and surge flow factors. The estimates used in the On -Site Wastewater Treatment Systems Standards may be greater than those discussed here. Denitrification Reductions Denitrification is a process that occurs in the septic system drain field whereby certain bacteria oxidize the nitrate (NO3) in the wastewater and release nitrogen gas (N2) to the atmosphere. Due to the biologic processes in the shallow soils, nitrogen in the drain field may undergo a reduction between 10 percent to 35 percent. Soils with higher clay content, moist soil conditions, high pH, and organic material denitrify by about 35 percent, and soils with high sand content tend to denitrify at a lower rate of about 10 percent. A denitrification factor of 35 percent was selected for the Site because of the clayey soil present at the percolation test location. LOGE 2147 Page 12