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Nitrate Loading Study 1 rarracon Rowe Property s Lodi, CA November 6, 2017 ■ Terracon Project No. NA177059 3.5 Quantity and Quality of Wastewater from Project The following discussion is for determining the long-term wastewater flow generated from the proposed development for the nitrate loading analysis and should not be used for septic system 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 Disposal Standards (2003), 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 USGS California Water Science Center California Water Use 2010 Data, average daily domestic use per capita was estimated at 69-gallons per day. Per conversations with Mr. Estrada, the EHD recommends a residential use rate of 70- gallons per person/day. According to Ms. Rowe, the site existing three bedroom residence is occupied by two residents year round. Ms. Rowe indicated the proposed new residence will be occupied by two residents year round. 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 flor rate. The flow rates selected for the uses associated with this project are presented below. Table 2. Existing and Proposed Quantity of Effluent. Average Total Quantity per Average Category People Person days of use Average Daily Flow per Day (gallons per per year day) Existing (2 people x 70 gal. per day x 365 days Residence 2 70 365 per year)/365 days per year= 140.0 gpd Proposed (2 person x 70 gal. per day x 365 days Residence 2 70 365 per year)/365 days per year= 140.0 gpd Estimated Average Daily Flow 280.0 gallons per day Responsive a Resourceful . Reliable 6