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Soil Suitability / Nitrate Loading Study 1 �erracon Lease Property ■ Acampo, California December 17, 2021 ■ Terracon Project No. NA217090 Table 4. Exoected Onsite Maximum Seotic Tank Usage - canons per day (gpd) The maximum daily flow rate for the existing residence is 420 gpd. The proposed modular residence is anticipated to add 420 gpd for a combined total of 840 gpd. 1.4 Groundwater Information 1.4.1 Groundwater Depth and Gradient Groundwater was not encountered within our borings which were drilled between approximately 2 and 21 feet below ground surface (bgs). According to the California Department of Water Resources Sustainable Groundwater Management Act (SMGA) Data Viewer, depth to groundwater was reported between approximately 70 and 80 feet bgs in Spring 2019 and 80 to 90 feet bgs in Fall 2019. Based on a review of GeoTracker, groundwater flow direction was reported to the south- southwest at a facility located approximately 0.50 miles east-southeast of the site. The groundwater flow direction and the depth to shallow, unconfined groundwater, N 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 stone 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 a Resourceful a Reliable 7 Average effluent Maximum septic Residence Number of bedrooms Number of people per quantity per person Tank Usage bedroom (gpd') (Gper) Existing 3 2 70 420 Proposed Modular 3 2 70 420 Total 840 - canons per day (gpd) The maximum daily flow rate for the existing residence is 420 gpd. The proposed modular residence is anticipated to add 420 gpd for a combined total of 840 gpd. 1.4 Groundwater Information 1.4.1 Groundwater Depth and Gradient Groundwater was not encountered within our borings which were drilled between approximately 2 and 21 feet below ground surface (bgs). According to the California Department of Water Resources Sustainable Groundwater Management Act (SMGA) Data Viewer, depth to groundwater was reported between approximately 70 and 80 feet bgs in Spring 2019 and 80 to 90 feet bgs in Fall 2019. Based on a review of GeoTracker, groundwater flow direction was reported to the south- southwest at a facility located approximately 0.50 miles east-southeast of the site. The groundwater flow direction and the depth to shallow, unconfined groundwater, N 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 stone 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 a Resourceful a Reliable 7