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ATTACHMENT 1 1-3 <br /> NITROGEN EFFLUENT LIMIT EVALUATION <br /> ORDER WQ 2014-0153-DWQ <br /> GENERAL WASTE DISCHARGE REQUIREMENTS <br /> FOR SMALL DOMESTIC WASTEWATER TREATMENT SYSTEMS <br /> Step A— Flow and Site-Specific Considerations <br /> The following considerations shall be evaluated to determine if a nitrogen effluent limit is <br /> appropriate. <br /> Al Exceed 20,000 gpd Flow Rate? The General Order allows a flow rate up to 100,000 <br /> gpd. However, discharges with flow rates less than 20,000 gpd are not required to <br /> meet a nitrogen effluent limit. <br /> A2 Shallow Groundwater? Shallow groundwater conditions are defined by the OWTS <br /> Policy Table 2, Minimum Depth to Groundwater and Minimum Soil Depth from the <br /> Bottom of the Dispersal System (reproduced as Table 5 below). <br /> Table 5: Minimum Depth to Groundwater and Minimum Soil Depth <br /> from the Bottom of Dispersal System <br /> Percolation Rate a Depth to Groundwater <br /> Perc Rate <_ 1 MPI Additional Treatment Required <br /> 1 MPI <_ Perc Rate <_ 5 MPI 20 Feet <br /> 5 MPI <_ Perc Rate :5 30 MPI 8 Feet <br /> 30 MPI <_ Perc Rate <_ 120 MPI 5 Feet <br /> Perc Rate >_ 120 MPI Engineered Disposal Required <br /> a. Perc Rate denotes percolation rate. MPI denotes minutes per inch. <br /> b.The minimum depth to groundwater is measured from the base of the infiltration surface <br /> to the seasonally high groundwater table or first saturated interval. <br /> A3 Excessive Percolation Rate/Fractured Environment? An excessive percolation rate <br /> is defined as a combination of percolation rate and depth to groundwater that does not <br /> comply with the conditions presented in Table 5. <br /> A fractured environment is defined as less permeable rock with porosity resulting from <br /> fractures that allows groundwater to flow through the fractures and has either of the <br /> following: a) No unconsolidated soil cover, or b) Unconsolidated soil cover that <br /> possesses an excessive percolation rate (that does not comply with the conditions <br /> defined in Table 5. <br /> A4 Exceed Domestic Wastewater Strength? Typical domestic wastewater strength is <br /> presented in Finding 8 of the General Order. Alternative domestic wastewater <br /> strengths may be based upon other per capita flow rate assumptions. The data <br /> presented in the General Order may be used; alternative characterizations from <br /> textbook and/or governmental organizations (e.g. U.S. Environmental Protection <br /> Agency) may be acceptable at the discretion of Regional Water Quality Control Board <br /> (Regional Water Board) staff. <br /> September 23, 2014 <br />