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Soil Suitability/ Nitrate Loading Study Irerracon Gribaudo Property ■Acampo, CA November 12, 2019 ■ Terracon Project No. NA197081 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 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 9. Typical Quantity of Effluent from Sources. Average Total Number effluent Average °f people quantity days of Average daily flow APN Building per bedrooms per use per (gpd*) day person year (gpd*) (3 bedrooms x 2 people 017- Existing 3 per bedroom x 70 gal. per 260-31 bedroom 2 3 70 365 day x 365 days per year)/ residence 365 days per year= 420 gpd 017- Future residence 260-30 (if applicable) Up to 5,500 gpd *gpd -gallons per day Regarding APN 017-260-31 (2.0 acre parcel), the average daily flow for the existing three bedroom residence is 420 gallons per day. As the existing breakroom/kitchen and restroom are no longer used and are not anticpated to be used, the buildings were not included in the wastewater flow calculation. Regarding APN 017-260-30 (35.81 acre parcel), there are currently no future development plans for the parcel. For the purpose of the NLS and as a worst case scenario, Terracon calculated wastewater flow up to 5,550 gallons per day for a future residence (if applicable). Responsive■ Resourceful ■ Reliable 15