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Soil Suitability/ Nitrate Loading Study Addendum Letter Irerracon Nostra Vita Winery Lodi, California May 20, 2019 revised June 10, 2019 Terracon Project No. NA197023 The percolation tests were conducted in accordance with the requirements of the San Joaquin County EHD on May 17, 2019 per Procedure#2. Terracon added clear water approximately 0.5 feet above the top of the gravel and recorded the drop in water level at thirty minute intervals over a four hour period. Measurement of the water level during the percolation test was from a fixed reference point on the PVC casing using a calibrated Solinst electric water level detector with a depth accuracy of 0.01 feet. All tabulated values on the field data sheet are in decimal feet. Table 3. Summary of Percolation Tests. Test No. Percolation Test Percolation Rate Comments Date Tested Depth(inch) (minutes/inch) Test Duration (see notes) P3 Satisfactory Percolation 05/17/2019 42 8.62 4 hours Rate P2 42 8.33 4 hours Satisfactory Percolation 05/17/2019 Rate A satisfactory percolation rate is 60 minutes per inch or less for shallow leach lines and 30 minutes per inch or less for septic pits per SJEHD, Onsite Wastewater Treatment Standards, January 2017. As the site was permitted for one percolation test, Terracon selected the control boring P3 to be observed by Ms. Sukhreet Kaur, EHD representative on May 17, 2019. Although boring P2 was not observed by the EHD, both borings demonstrated satisfactory percolation rates. A copy of the field data for boring P3 is included in the Attachments. Average Daily Flow Rates (Max Flow x# Days used per year/ 365 days per year) For the purpose of the nitrate loading analysis, a long term average daily flow rate of 197.26 gpd was calculated for the special events which are held 30 days per year (2,400 gpd x 30 days per year/365 days per year). The remaining buildings will remain in use year round; therefore, a long term average daily flow rate was not calculated. The average total nitrogen concentration of domestic wastewater is normally considered to be 20 to 85 mg/L-N with 35 to 45 mg/L-N being typical (Crites and Tchobanoglous, 1998). It is estimated that commercial use will have higher concentrations of total nitrogen when compared to residential use. NOA reported the average total nitrogen concentration of wastewater to be 85 mg/L-N for the winery facility with 25%denitrification factor. Terracon concurs with the NOA SSNLS 85 mg/L- N nitrogen concentration of wastewater and 25% denitrification factor and recommends a deep percolation of rainfall rate of 4.49 inches per year. Nitrate Loading A nitrate loading scenario was performed for each building with a septic tank to determine the Responsive■ Resourceful ■ Reliable 6