SR0081254 SSNL - Laserfiche WebLink

Home Browse Search

30 August 2019 AdvancedGeo AGE Project No. 19-4819 Environmental Page 11 of 15 9.2. IMPACT OF RAINFALL CONTRIBUTION TO NITRATE LOAD The rainfall of the area has been estimated for the nitrate loading analysis. Deep percolation is estimated by calculating the average monthly rainfall and evapotranspiration of the site area. If average monthly rainfall exceeds average monthly potential for evapotranspiration (ETo) there is a potential for deep percolation without consideration for runoff. Average potential ETo was estimated from data obtained from the California Irrigation Management Information System (CIMIS) Ripon Station #249. The average rain fall data for the area was gathered from the Western Regional Climate Center (WRCC). The averages were calculated based on data collected at the Tracy Pumping Plant between 1955 and 2016, the annual rain fall average for the area is 12.03 inches. The average ETo for the area is 57.0 inches/year. The average monthly rainfall does not exceed the average monthly ETo. 9.3. CURRENT ON-SITE SOURCES OF NITRATE Septic systems, rainfall and agriculture (adjacent property to the west) are sources of nitrates (fertilizers) present on or around the property. The current site usage includes a 2,100-square foot house with four bedrooms and three bathrooms, and an approximately 600-square foot annex/shed. Residential use includes showering/bathing, clothes washing, cooking, and hand washing. The reasonable or maximum usage of wastewater for the four-bedroom house is 150 gpd per bedroom for a total of 600 gpd. The total nitrate-nitrogen (NO3_N) average concentrations in domestic waste ranges between 20 to 85 milligram total nitrogen liter (mg/1-N) with an average of 45 mg/1-N when washing and sanitation is considered. The weighted average calculation for total nitrogen concentrations for onsite residential flow is proposed as the following: • Residential volume 600 gpd. • Home use concentration 45 mg/1-N (EHD standard). • The flow concentration of 27,000 mg/1-N gallon. 9.4. FUTURE ON-SITE SOURCES OF NITRATE The future site usage includes the addition of a 2,100-square foot residence with two bedrooms and two bathrooms for residential use. Residential use includes showering/bathing, clothes washing, cooking, and hand washing. The reasonable or maximum usage of wastewater for the two-bedroom mobile home is 150 gpd per bedroom for a total of 300 gpd.