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June 14,2005 NOA Project Number: E05066A r 4.4 Future On-Site Sources of Nitrate 4.4.1 Quantity and Quality ofDomestic Wastewater From Proposed Project The following discussion is for determining the long-term waste water flow generated from the 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 the numbers discussed here are based on long-term averages. A three bedroom home is present on the site. A three bedroom home is presumed to be occupied by up to four people over the long term. Because of the development of the Trucking Company and the size of the parcel,it is unlikely that a second dwelling unit will be built on the property. However,we will still assume that a two a oom second dwelling unit is built on the property with '- three people living in it over the long terxThe nitrate loading estimate will assume seven residents will use 70 gallons per day over the long term. With the development of the Trucking Company a second septic system is to be installed on the property. The trucking company employs six drivers and two office workers. The office workers will be working 8 hour days Monday throug Friday. The J=ical office employce use is 13 gallons.ner day.The six drivers arrive at 6:00 in the morning and then leave for the work day and arrive back at 4:00 pm. Because the drivers are out of the office all day, they will be treated similar to a `customer use'atfive gallons per, day..The trucking company also has maintenance workers that work on the �- trucks when they are needed. This averages to about two to four workers per day. For the estimate we will assume that four workers will use the restroom, and since they are at the site for most of a work day, the workers will be treated as an`office use' at 13 gallons per day.The trucking company �- also estimates that they will receive two customers per day, even though most of their business is done over the phone. In summary,-there will be six office employees/maintenance workers using 13 gallons per day and 8 customers/truck drivers using five gallons per day. 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 typical use rate is 45 gallons per day for a resident. �• The higher estimate of Crites and Tchobanoglous will be used for residential use.Also, the estimates for Office Employee and Public Lavatory will be used from that book as well. �• 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 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 in the following table. 4 "004 b"