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RECEIVED JAN 13 1010 ENVINUNW:NTAL HEATH DEPARTMENT 4.2 Description/discussion of any existing and/or potential groundwater contamination issues in the general location of the site: Description of existing or potential groundwater contamination issues in the general location of the site are referred to in Section 4.2 of the Soil Suitability Report prepared by Dillon& Murphy that is attached in the Appendix. 4.3 Description of the current use of groundwater at the site and of the future expected use of groundwater as related to the proposed development project: Based on the most recent results from San Joaquin County's "Flood Control and Water Conservation District" Groundwater Report Fall 2017,the estimated depth to groundwater was determined to be 100 feet below the surface. This information is close to the data collected from the California Department of Water Resource's Water Data Library. The results of the historic depth to ground water show that the relative depth has not changed drastically throughout the years. The proposed improvements will not have a negative effect on the current depth to ground water. See appendix for the site's depth groundwater tables and diagrams. 5.0 SOURCES AND CALCULATED IMPACT OF NITRATE TO GROUNDWATER 5.1 Description of all current off-site sources of nitrate to soil and groundwater in the general up gradient area and the contribution of nitrate load from these sources to the project site: Current off-site sources of nitrate to soil and groundwater in the general up gradient area and the contribution of nitrate loads are agriculture and neighboring homesites with septic systems with minimal to no current impact to the site. 5.2 Description of impact of rainfall contribution of nitrate load to the project site: The impact of rainfall contribution on the project site was completed to determine the nitrate load. The average monthly precipitation and evapotranspiration are required to calculate the site nitrate load. These two values are used to estimate the deep percolation. The deep percolation is estimated by analyzing the difference between the monthly average precipitation and the envotranspiration, when the evotranspiration exceeds the monthly average precipitation. These calculations are attached in the Appendix. The data for the potential envotranspiration water was obtained from the California Irrigation Management Information System (CIMIS). The project is located within an area designated as Zone 12. Based on the values for this area along with the average monthly precipitation values obtained from the Western regional Climate Center(Station 242) for the Lodi region an estimate of the deep percolation of rain for the project was determined. The results for the deep percolation at the site were 9.44 in./year. The nitrate concentration is estimated to be about 1 mg/L-N. (Hantzche and Finnemore, 1992). 5.3 Description of all current on-site sources of nitrate to soil and groundwater and the contribution of nitrate load from these sources to the project site: The only source of nitrates is the existing septic system in use by an existing parcel for residential purposes. The existing septic system was accounted for when determining the approximate nitrate concentration,the site could expect with the proposed development. 2