Laserfiche WebLink
Soil Suitability /Nitrate Loading Study Irerracon <br />Munsch Property ■ Lodi, California <br />January 7, 2022 ■ Terracon Project No. NA217092 <br />2.3.4.1 Quantity and Quality of Wastewater from Project <br />The following discussion is for determining the long-term wastewater flow generated from the <br />proposed development for the nitrate loading analysis and should not be used for septic system <br />design purposes. Typically, use estimates for the sizing of septic systems include a peak use <br />factor, whereas the numbers discussed here are based on long-term averages. <br />The estimated sewage flow rates for use categories are available from a number of references. <br />The uses presented below were guided by the San Joaquin County On -Site Wastewater <br />Treatment Standards (OWTS) dated 2017, Crites and Tchobanoglous (1998), and EPA (1980). <br />Table 4-2 of the text from Crites and Tchobanoglous indicates that the typical residential use rate <br />is 70 -gallons per day per bedroom. The EPA Design Manual (Table 4-6) indicates the typical use <br />rate is 45 -gallons per day per resident. Based on a review of the United States Geological Survey <br />(USGS) California Water Science Center California Water Use 2010 Data, average daily domestic <br />use per capita was estimated at 69 -gallons per day. <br />In February 2020, the EHD approved a revised calculation method for long term average <br />discharge of waste water and recommended 100 gallons for the first bedroom and 50 gallons for <br />each additional bedroom. <br />The following table presents the proposed septic wastewater use for the site. The rates presented <br />from the references provide general guidance but do not always reflect a match in usage. Should <br />any of the above information provided to our office change or is inconsistent with what is stated, our <br />office shall be contacted to make any necessary modifications to our calculations. Examination and <br />professional judgement, and experience shall be used when selecting a reasonable flowrate. <br />Table 9. <br />Typical Quantity of Effluent. <br />-gpa - gauons per aay <br />Based on a review of the above table, the long term average discharge rate for the proposed <br />three-bedroom residence is anticipated to be 200 gpd. The proposed two-bedroom second <br />residence is anticipated to add approximately 150 gallons per day for a combined long term <br />average discharge rate of 350 gpd. <br />Responsive ■ Resourceful ■ Reliable 15 <br />Average Effluent <br />Average Effluent <br />Number of total <br />Quantity for <br />Quantity for Additional <br />Long Term Average <br />Residence ID <br />bedrooms <br />Bedroom 1 <br />Bedroom(s) <br />Discharge Rate <br />(gpd") <br />(gpd.) <br />(gpd*) <br />Proposed 3 - <br />bedroom <br />3 <br />100 x 1 <br />50 x 2 <br />200 <br />Residence <br />Proposed 2 - <br />bedroom Second <br />2 <br />100 x 1 <br />50 x 1 <br />150 <br />Residence <br />Total gpd <br />350 <br />-gpa - gauons per aay <br />Based on a review of the above table, the long term average discharge rate for the proposed <br />three-bedroom residence is anticipated to be 200 gpd. The proposed two-bedroom second <br />residence is anticipated to add approximately 150 gallons per day for a combined long term <br />average discharge rate of 350 gpd. <br />Responsive ■ Resourceful ■ Reliable 15 <br />