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L LMarch 22, 2005 NOA Project Number: E040132A ` proposed residences 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 Lthe numbers discussed here are based on long-term averages. For Parcel 1 (181-090-11), a three (3) bedroom home.The three (3) bedroom home is presumed to be occupied by up to four people over the long term.A second dwelling unit, occupied by a Lpotential thrree people, could be placed on the lot as well. Therefore, a total of seven people per parcel will be e uses to calculate the residential septic tank usage for parcel 1. For Parcels 2 (181-090-02),it is likely that a three bedroom home will be built.A three bedroom house is presumed to be occupied by up to four people over the long term. A second dwelling unit, occupied by a potential three people, could be placed on the lot as well. Therefore, a total of seven people per parcel will be used to calculate the residential septic tank usage for parcel 2. 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). The text from Crites and Tchobanoglous (1998) (Table 4-2) indicates that the typical residential use rate is 70 gallons per day. The EPA (1980) Design Manual (Table 4-6) indicates the tgpical use ra�gallons per day for a resident The following tables presents the septic waste water uses associated with the Site. The rates presented from the references provide general guidance but do not always reflect a match in usage. Careful exa+*oration,professional judgement,and experience are necessary to select a reasonable flow rate estimate. The flow rates selected for the uses associated with this project are presented in fr the following table. Table 1. Typical Q antity of Effluent for Parcel land 2. Category Total People per Average Quantity per Average Daily Flow Day Person Per Parcel Residential 7 70 gal/day/person 7 residents/day*70 gpd/person =490 gpd Note —gpd is gallons per day. L For both Parcels, the total daily waste water quantity is 490 gallons per day. LThe average total nitrogen concentration of domestic waste water is normally considered to be 20-85 mg/L-N (Crites and Tchobanoglous, 1998). For the purposes of the nitrate loading estimate, the long-term average concentration for total nitrogen in waste water is estimated to be 45 mg/L-N. L 9 P L 5 x7 L