SSNL - Laserfiche WebLink

Home Browse Search

Nitrate Loading Study Irerracon Valencia Property■ Ripon, California September 6, 2018 ■ Terracon Project No. NA187044 3.5.3 Impact of Nitrate Loading to Nearby Water Sources Based on a review of the USGS Avena (1994) California Quadrangle topographic map (Appendix A), the site is located at approximately 80 feet above mean sea level with a topographic gradient toward the west. The nearest surface water source to the site is an unidentified irrigation canal located approximately 1,000 feet southwest of the site. As the subject property is relatively flat, we do not foresee percolating effluent affecting the surface water resources. 4.0 DISCUSSION OF NITRATE LOADING RESULTS RELATIVE TO PROPOSED METHOD OF WASTEWATER DISPOSAL 4.1 Total Nitrate Impact Based on the method and assumptions described, the result of the nitrate loading balance indicates that the proposed residential use on the site may cause a buildup of nitrates (22.7 mg/L- N) in the aquifer above the MCL of 10 mg/L-N. 4.2 Methods of Mitigation Mitigation may consist of the utilization of an advanced water treatment product such as those available by Orenco, which are specifically designed to lower nitrates at point of discharge. Other mitigation options include the use of a carbon source such wood chips. Based on the proposed usage, mitigation may be required by the EHD. 5.0 CONCLUSIONS AND RECOMMENDATIONS The proposed residential use has the potential to cause a buildup of nitrates (22.7 mg/L-N) above the MCL of 10 mg/L-N when an average double occupancy is calculated per bedroom. A groundwater well is not located on the site; therefore, a groundwater sample was not collected. Elevated nitrate levels (up to 70.4 mg/L-N) were reported in off-site groundwater wells located approximately one mile north and east of the site. Depth to groundwater is anticipated between 45 and 60 feet bgs. Agricultural land use on the site and vicinity is anticipated to be the highest contributor to nitrates in groundwater. If the EHD requires mitigation for the project, an advanced water treatment product or carbon source may be considered mitigation options. Responsive ■ Resourceful ■ Reliable 9