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EXHIBIT A: EXISTING CHAPTER 928 928.06 STREETS. UTILITIES AND PUBLIC SERVICES CODE 66R-8 (10) Sand Filters. (11) Low Impact Development Design including bioretention areas, grassed: A. Aquatic benches in Retention Basins and ponds. B. For redevelopment projects, ensure a 20 percent net reduction of the site impervious area. (f) Technical Basis. The plans will contain a statement of the rationale utilized to select the BMPs used to control pollution and to maintain and protect water uality. Ord. 2012-27. Passed 10-2-12.) 928.06 DEVELOPMENT SITES 5 ACRES OR LARGER. A development site that disturbs five (5) or more acres of land or will disturb less than five (5) acres, but is a part of a larger common plan of development or sale, which will disturb five (5) or more acres of land shall identify: (a) Storm Water Detention. The Post -Construction BMP(s) chosen must be able to detain storm water runoff for protection of the stream channels, stream erosion control, and improved water quality. (b) Structural BMPs. Structural (designed) Post -Construction storm water treatment practices shall be incorporated into the permanent drainage system for the site. (c) Pro erl Sized BMPs. The BMP(s) chosen must be sized to treat the water qua ity volume (WQv) and ensure compliance with Ohio's Water Quality Standards in OAC Chapter 3745-1. The WQV shall be equivalent to the volume of runoff froma 0.75 inch rainfall and shall be determined according to the following equation: (1) WQv = C * P * A / 12 where: WQv = water quality volume in acre-feet C = runoff coefficient appropriate for storms less than 1 inch (either using Table 1 or the following formula: C=0.85813 - 0.78i2 + 0.774i + 0.04 (where I = fraction of post -construction impervious area) P = 0.75 inch precipitation depth A = area draining into the BMP in acres. Table I Runoff Coefficients Based on the Type of Land Use LAND USE RUNOFF COEFFICIENT Industrial and commercial 0.8 High Density Residential (> 8 dwellings/acre) 0.5 Medium Density Residential (4 to 8 dwellings/acre) 0.4 Low Density Residential (< 4 dwellings/acre) 0.3 Open Space and Recreational Areas 0.2 (d) Where the land use will be mixed, the runoff coefficient should be calculated using a weighted average. For example, if 60% of the contributing drainage area to the storm water treatment structure is Low Density Residential, 30% is High Density Residential, and 10% is Open Space, the runoff coefficient is calculated as follows (0.6)(0.3) + (0.3)(0.5) + (0.1)(0.2) _ 0.35.