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APPENDIX B Page 3 of 3 <br />Holly Commerce Center Michaels TI’s, Formerly E&E Trading <br />Tracy, CA <br /> <br />Stockton San Jose Sacramento Modesto <br />3428 Brookside Rd. 111 N. Market St., #300 900 Howe Ave., #200 100 Sycamore Ave, #100 <br />Stockton, CA 95219 San Jose, CA 95113 Sacramento, CA 95825 Modesto, CA 95354 <br />t: 209.943.2021 t: 408.754.2021 t: 916.520.2777 t: 209.762.3580 <br /> <br />F:\17projects\17017 Holly Sugar Industrial\Civil\Septic Sizing - Prelim\17017 Holly Commerce Center E&E Nitrate Loading Memo <br />Ver 4.docx <br />Storm Water BMP Handbook for New Development and Redevelopment for an impervious <br />coefficient of 93% and a required capture rate of 80% the basin annually will capture approximately <br />70% of the total runoff and infiltrate it with a typical drawdown time of 48 hours. The basin will not be <br />planted and will not have standing water during months when the ET rate is high, however for the <br />sake of this analysis it is assumed that 5% of the water is lost to ET. <br /> <br />R2 = 45.57 ac-ft/yr x (70% - 5%) = 29.6205 ac-ft <br /> <br />R = R1 + R2 = 2.3757 ac-ft/yr + 29.6205 ac-ft/yr = 31.9962 ac-ft/yr <br /> <br />Therefore: <br /> <br />nr = Wnw(1-d)+Rnb / (W+R) <br /> = ((3.32 ac-ft/yr x 146 mg N/L) x (1-0.30) + (31.9962 ac-ft/yr x 0.10 ppm)) / (3.32 ac-ft/yr + 31.9962 ac- <br />ft/yr) <br /> = 9.698 ppm as nitrate-nitrogen (NO3-N) amount falls below the 10ppm threshold <br /> <br /> <br />V. Annual Rainfall-Recharge Value <br />Table 4 on Pages 6 and 7 of the Chesney Report Dated May 6, 2019 was placed in the report to illustrate <br />the impacts of grass growth on the leach field and the care that must be taken with landscape care and <br />irrigation. Per section II above the rate used for recharge is now calculated using the suggestions in <br />Attachment 1 and an annual rainfall depth of 9.5” per the attached County standard drawing D -3. <br /> <br />VI. Attachments <br />1. Attachment 1; Recommended Alternate Nitrate Loading Analysis for Heavily <br />Developed/Impervious Site Conditions <br />2. Future Expansion Area Exhibit and Calculations <br />3. San Joaquin County Standard Drawing D-3 <br /> <br />