SR0081007 SSNL - Laserfiche WebLink

Home Browse Search

Nitrate Loading Study Irerracon Morris Property ■ Ripon, California September 12, 2018 L4 Terracon Project No. NA187039 mg/L-NO3 (3 mg/L-N). Areas having 24.75 mg/L-NO3 (5.5 mg/L-N) or more are those in which nitrate concentrations may be increasing (Hull, 1984). DBCP (dibromochloropropane) is a nematicide and soil fumigant for vegetables and grapes. It is thought to cause health problems consisting of kidney damage, liver damage, and cancer. The use of DBCP was discontinued in 1979. EDB (ethylene dibromide) was used in gasoline to prevent lead deposits and build up. It was also used in pesticides and fumigants. Exposure to EDB is linked to many adverse health effects stemming from organ damage to cancer. Agricultural land use and septic systems in the area should be considered potential groundwater contamination sources. The concerns for groundwater contamination in this area are deemed moderate to high based on the agricultural land use and anticipated depth to groundwater between 45 to 60 feet bgs. 2.3 Current and Future On-Site Ground Water Uses According to Mr. Morris, there are no groundwater wells located on the site. Mr. Morris indicated the site will be developed with a grown watrTupply well forfum&e residential use. Based on the absence of an onsite groundwater well, a groundwater sample was not collected. 3.0 SOURCES AND IMPACT OF NITRATE TO GROUNDWATER 3.1 Current Off-Site Sources of Nitrate The adjoining properties consist of agricultural land primarily orchards and rural farm structures and/or residences. Terracon assumes the farm structures and/or residences are connected to individual septic systems based on the absence of municipal sewer systems in the area as reported on the San Joaquin County District Viewer. Therefore, off-site sources of nitrate include residential septic systems, agricultural land use, and natural processes. Based on information obtained from the DWR Water Data Library, between the years 1959 to 2012, dissolved nitrate was reported between 5 and 70.4 mg/L-N at three groundwater wells located within one mile north and northeast of the site. A groundwater study titled Addressing Nitrate In California's Drinking Water Technical Report 2 Nitrogen Sources and Loading to Groundwater dated 2012 prepared by the University of California Davis for the Tulare Lake Basin and Salinas Valley, indicated crop land contributed 96% of the human-generated nitrate sources to groundwater. The study indicated other minor contributors to nitrate in groundwater included waste water treatment plants, septic systems, corrals, lagoons and urban runoff. Based on the groundwater study, agricultural land use on the site and vicinity is anticipated to be the highest contributor to nitrates in groundwater. Responsive■ Resourceful■ Reliable 5