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Soil Suitability / Nitrate Loading Study Munsch Property ■ Lodi, California Irerracon January 7, 2022 ■ Terracon Project No. NA217092 Table 4. Expected On -Site Maximum Septic Tank Usage vauons per day (gpd) The maximum daily flow rate for the proposed 3 -bedroom residence is 420 gpd. The proposed 2 - bedroom second residence is 280 gpd. 1.4 Groundwater Information 1.4.1 Groundwater Depth and Gradient Groundwater was not encountered within our percolation test borings which were hand augered between 3.0 and 8.0 feet below grade surface (bgs). According to the California Department of Water Resources Sustainable Groundwater Management Act (SGMA) Data Viewer, in Spring 2021 depth to groundwater was reported between approximately 40 to 50 feet bgs, in Spring of 2020 depth to groundwater was between 30 and 40 feet bgs and in Fall of 2019 depth to groundwater was between 30 and 40 feet bgs. Based on a review of the Spring and Fall elevation contours groundwater gradient was reported to the southeast with a southwest groundwater gradient. The groundwater flow direction and the depth to shallow, unconfined groundwater, if present, would likely vary depending upon seasonal variations in rainfall and other hydrogeological features. Without the benefit of on-site groundwater monitoring wells surveyed to a datum, groundwater depth and flow direction beneath the site cannot be directly ascertained. 1.4.2 Potential Groundwater Contamination Issues Potential groundwater contamination can occur from a number of sources including historical petroleum hydrocarbon use, agricultural activities, dairies, septic systems, and storm water infiltration. As per EHD requirements nitrate as N and 1,2-dibromo-3-chloropropane (DBCP) have been included as part of the SSS discussion. Identifying potential groundwater contamination other than nitrates and DBCP is beyond the scope of work for this report. The presence of nitrates is not uncommon in shallow groundwater aquifers in San Joaquin County and other parts of the Central Valley. Nitrate in groundwater occurs as a result of the application Responsive ■ Resourceful ■ Reliable 7 Number of people per Average effluent Maximum Septic Residence Number of bedrooms bedroom quantity per person Tank Usage (gpd') (gpd`) Proposed 3 -Bedroom Residence 3 2 70 420 Proposed 2 -Bedroom Second Residence 2 2 70 280 vauons per day (gpd) The maximum daily flow rate for the proposed 3 -bedroom residence is 420 gpd. The proposed 2 - bedroom second residence is 280 gpd. 1.4 Groundwater Information 1.4.1 Groundwater Depth and Gradient Groundwater was not encountered within our percolation test borings which were hand augered between 3.0 and 8.0 feet below grade surface (bgs). According to the California Department of Water Resources Sustainable Groundwater Management Act (SGMA) Data Viewer, in Spring 2021 depth to groundwater was reported between approximately 40 to 50 feet bgs, in Spring of 2020 depth to groundwater was between 30 and 40 feet bgs and in Fall of 2019 depth to groundwater was between 30 and 40 feet bgs. Based on a review of the Spring and Fall elevation contours groundwater gradient was reported to the southeast with a southwest groundwater gradient. The groundwater flow direction and the depth to shallow, unconfined groundwater, if present, would likely vary depending upon seasonal variations in rainfall and other hydrogeological features. Without the benefit of on-site groundwater monitoring wells surveyed to a datum, groundwater depth and flow direction beneath the site cannot be directly ascertained. 1.4.2 Potential Groundwater Contamination Issues Potential groundwater contamination can occur from a number of sources including historical petroleum hydrocarbon use, agricultural activities, dairies, septic systems, and storm water infiltration. As per EHD requirements nitrate as N and 1,2-dibromo-3-chloropropane (DBCP) have been included as part of the SSS discussion. Identifying potential groundwater contamination other than nitrates and DBCP is beyond the scope of work for this report. The presence of nitrates is not uncommon in shallow groundwater aquifers in San Joaquin County and other parts of the Central Valley. Nitrate in groundwater occurs as a result of the application Responsive ■ Resourceful ■ Reliable 7