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f February 15,2006 'NOA Project Number. E06006A Tchobanoglous (199 8) (Table.4-2) indicates that the typical residential use rate is 70 gallons per day. F The EPA (1980) Design Manual (Table 4-6) indicates the typical use rate is 45 gallons per day for a resident. The higher estimate of Crites and Tchobanoglous will be used for residential use. The text from Crites and 1998ous Tchobanoglous g ( ) (Table 4-2) indicates that the typical office worker r (includes commercial workers) use rate is 13 gpd. The E13A (1980) Design Manual (Table 4-6) F1indicates the typical use rate is 14.5 gpd for an office worker: Since the Crites and Tchobanoglous (1998) information is the most current available, our office believes it provides the best estimate of waste water flow for the office/commercial worker category. Therefore, 13 gpd will be used for each employee. To identify the impact to the waste water flow from customer visits, each visit to the Site is estimated to generate 5 gallons of waste water. The following table 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 examination, 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 next. I Table 1. T ical Quantity of Effluent Category Total People per Average Quantity per Average Daily Flow Day Person . Per Parcel Residential 7 70 gpd/resident _7 residents* 70 gpd=490 gpd Commercial-- 2(shift 1) 13 d2 employees* 13 gpd*5/7 = 18.6 gpd Employee 2 (shift 2) /em pto yee 2 employees* 13 gpd* 5/4= 32.5 gpd CCustomerl 60 5 gpd/customer 60 customers* 5 gpd=300 gpd omerciNote —gpd is gallons per day;5/7 is a conversion factor for the 5-day work week(shift 1);5/4 is a conversion factor for a 10-hour work day(shift 2). hFor the subject property, the total daily waste water quantity is 841.1 gallons per day. The average total nitrogen concentration of domestic waste water is normally considered to be 20-85 mg/L-N with 35 to 45 mg/L-N being typical (Crites and Tchobanoglous, 1998_). It is estimated that commercial use will have higher concentrations of total nitrogen when compared to residential use. It is estimated that the average concentration for total nitrogen in waste water for J the project is approximately 60 mg/L-N over the long term. A conservative total nitrogen concentration of 60 mg/L-N will be utilized for both the residential and commercial uses for the FJpurposes of this calculation. 0A k0 3 � . - 1 t