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F GROUNDWATER INFORMATION S§ 2.0, etc., SSS§ 4.0, etc. Groundwater depths and elevations throughout San Joaquin unty are illustrated on maps published by the County Flood Control and Water Conservation District. The Spring 1983 Lines of Equal Depth Map indicates the depth to water under the site at approximately 50 ft. The Fall 2000 Lines of Equal Depth Map also illustrates approximately a 50 ft depth to groundwater. The Spring 2023 Lines of Equal Depth Map indicates depth to groundwater at approximately 60 ft, thus indicating a 10-ft drop in water table depth in 23 years. From the Lines of Equal Elevation Maps, groundwater directional flow appears to be in a southeast direction in 2000 and an easterly direction in 2023. Properties 1.5 miles to the east are currently in agricultural production. Considering this area has been farmed for decades, there is potential for nitrate contamination to the underlying groundwater from nitrogen fertilizer applications, residual organic matter decomposition, and OWTSs. Domestic water is provided by California Water Service; consequently, there is no onsite well. The well that served the razed domestic residential structure has been destroyed. E. SURFACE WATER INFORMATION NLS§ 3.0, etc. The total subject property area is net 4.85 acres and will consist of impervious buildings, asphalt/concrete hardscape, and pervious areas such as stormwater retention and the effluent disposal area. All impervious areas flow into the stormwater percolation pond area. The rainfall recharge factor used in the Hantzsche-Finnemore equation below has been derived from a document found in Appendix E, which illustrates the water balance analysis of Net Rainfall Recharge (NRR or R as referenced below). The data presented in this document indicates an NRR of 8.82" for the Stockton area and is therefore applicable for this project. III. NITRATE LOADING STUDY FINDINGS A. WASTEWATER FLOW VOLUME PROJECTIONS AND CHARACTERISTICS Wastewater Flow Volume Projections To determine nitrate-nitrogen loading from any project, wastewater flow volumes must be determined as accurately as possible. Fixture units for the future office building and shop are illustrated on the Floor Plan in Appendix H. Upon complete build-out, there will be 6 toilets, 7 lavatories, 2 showers and 1 mop sink. Average Daily Flows (ADF) for nitrate loading calculations are best determined by realistic fixture use: A toilet flush+hand washing total approx. 1.78 gallons (1.28 gals-New CA Standard)+0.5= 1.78 gals) Assume there are on average 3 flushes each hour, for each of the 6 toilets, 10 hrs per day: 1.78 gals/toilet flush x 3 flushes/hr x 10 hrs/day x 6 toilets= 320 gpd ADF. Page -4- Chesney Engineering, Inc.