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`MEMORANDUM Page 2 of 2 00■ Holly Commerce Center Septic Basis of Design Tracy, CA �E S I E G F R I E D III. Waste Generation Rate Determination In order to determine the Average Daily Flow for the building a waste generation rate of gallons per day per employee must be established and multiplied by the employee count established in Section II above. The 2017 County Standards referenced in Section I dictate that the waste generation rate for an Industrial Building with no food cafeteria is to be 15gal/person/day, however the proposed use is a dry storage warehouse which will generate less waste than an industrial building. Table H 201.1(2)of Appendix H of the CPC is silent on the waste generation rate for a dry warehouse but Note 3 in CPC Appendix H Table 201.1(2) states that"Because of the many variables encountered, it is not possible to set absolute values for waste/sewage flow rates...The designer should evaluate each situation and, where figures in this table need modification, they should be made with concurrence with the Authority Having Jurisdiction." This notes further supports the need for the County AHJ and the designer to establish logical and agreed upon waster generation rates. Furthermore, the EPA Design Manual for Onsite Wastewater Treatment and Disposal Systems Table 4-6 provides another data point with a range of values for an industrial building between 7.9 and 17.2gal/person/day, but no dry storage warehouse range. Coupling the varying data with a recently approved dry storage warehouse project in San Joaquin County on Schulte Road that utilized a waste generation rate of 7.5gal/person/day we would like to establish 7.5gal/person/day as the design parameter for waste generation for the dry storage warehouse use, we are proposing. To further support the use of 7.5gal/person/day we would like to offer the following logic. Each restroom use by an employee can be assumed to be the following utilizing low flow fixtures: Water Closet: 1.1 gallons (Afwall or Madera are examples) Lavatory: 0.35 gallons (0.35gpm faucet for 1 minute, Sloan SF-2350 is an example) Total: 1.45 gallons If each employee works a 10 hour shift and uses the restroom every other hour this results in 5 uses per day or 7.25 gallons per day which is less than the proposed rate. IV. Conclusion Based on the above information we request the following be approved as the basis of sanitary sewer design for the dry storage warehouse use at Holly Commerce Center: 1. 7.5gal/person/day shall be used as the waster generation rate for both Group S Warehouse and Group B Office occupancies. 2. That occupancy is based on the CPC Chapter 4 Table 422.1 and Table A. Stockton San Jose Sacramento Modesto 3428 Brookside Rd. 111 N. Market St.,#300 109 Scripps Drive 100 Sycamore Ave,#100 Stockton, CA 95219 San Jose, CA 95113 Sacramento, CA 95825 Modesto, CA 95354 t: 209.943.2021 t:408.754.2021 t: 916.520.2777 t: 209.762.3580 F:\17projects\17017 Holly Sugar Industrial\Civil\Septic Sizing-Prelim\17017 Holly Commerce Center Septic Basis of Design Memo Ver 1.docx