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lierracon Soil Suitability / Nitrate Loading Study Azevedo Property Acampo, CA June 19, 2019 Terracon Project No. NA197009 design purposes. Typically, use estimates for the sizing of septic systems include a peak use factor, whereas the numbers discussed here are based on long-term averages. The estimated sewage flow rates for use categories are available from a number of references. The uses presented below were guided by the San Joaquin County On-Site Wastewater Treatment Standards (OWTS) dated 2017, Crites and Tchobanoglous (1998), and EPA (1980). Table 4-2 of the text from Crites and Tchobanoglous indicates that the typical residential use rate is 70-gallons per day per bedroom. The EPA Design Manual (Table 4-6) indicates the typical use rate is 45-gallons per day per resident. Based on a review of the United States Geological Survey (USGS) California Water Science Center California Water Use 2010 Data, average daily domestic use per capita was estimated at 69-gallons per day. The EHD recommends a residential use rate of 70-gallons per person/day times two persons per bedroom. The OWTS manual suggests that 15 gallons per person is typical for industrial building employees which is similar to the agricultural building. The following table presents the proposed septic wastewater use for the site. The rates presented from the references provide general guidance but do not always reflect a match in usage. Should any of the above information provided to our office change or is inconsistent with what is stated, our office shall be contacted to make any necessary modifications to our calculations. Examination and professional judgement, and experience shall be used when selecting a reasonable flowrate. Table 10. Typical Quantity of Effluent from Sources. Category Total people per day Number of bedrooms Average effluent quantity per person (gpd*) Average days of use per year Average daily flow (gpd") Residence 2 4 70 365 (4 bedrooms x 2 people per bedroom x 70 gal. per day x 365 days per year / 365 days per year = 560 gpd Agricultural Buidling 4 15 365 (4 employees x 15 gal. per day x days per year)/365 days perye 60 Total 620 gpd .. *gpd - gallons per day Based on a review of Table 10, the average daily flow for the existing residence is 560 gallons per day. The proposed i-estroom for the agricultural building will add 60 gallons per day for a total of approximately 620 gallons per day. The average total nitrogen concentration of domestic wastewater is normally considered to be 20 to 85 mg/L-N with 35 to 45 mg/L-N being typical (Crites and Tchobanoglous, 1998). It is estimated Responsive Resourceful t, Reliable 15