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<br />Final Groundwater Lake Water -Quality. The stormwater channel. entering the site will <br />collect surface water runoff from a mostly urbanized watershed located on the western <br />edge of the City of Greeley. The watershed encompasses less than 2 square miles. The <br />basin is primarily made up of established residential and commercial communities. The <br />commercial communities include retail. businesses and office buildings. In addition, the <br />basin contains a country club and associated golf course, community college campus, and <br />various schools and parks.. <br />Surface water runoff from these areas would be expected to carry contaminants typical of <br />urban runoff including= suspended solids .(organic. detritus and clay, silt,. and grit), <br />dissolved inorganic -ions (road salts); a variety of dissolved heavy metals (fallout from- <br />automobile exhaust and corrosion byproducts), organic compounds (oils and other <br />petroleum products), and 'suspended bacteria and viruses (animal and human waste). <br />However,, taking into account City of Greeley. programs and practices for stormwater <br />quality protection; the watershed characteristics, and the design of the stormwater <br />channel itself, it is expected that many of ahese contaminants would be significantly <br />reduced or eliminated from the stormwater runoff. Concentrations of these contaminants. <br />in . the stormwater, delivered to.. the groundwater lake would not be expected to <br />significantlyimpact surface water or groundwater quality. <br />The City of Greeley recently applied for coverage under the Colorado Phase II Municipal <br />Stormwater Discharge Permit: The measures under this permit include public education <br />and outreach, public participation/involvement, illicit discharge detection and <br />elimination', construction site stormwater runoff control, post-construction stormwater ' <br />management, and pollution prevention/good 'housekeeping for municipal operations. <br />Once applied, these measures have been shown to significantly reduce most pollutant . <br />concentrations in urban runoff It should also be noted that the City of Greeley operates <br />separate,stormwater and domestic sewer systems. Therefore, during major storm events, <br />there is no, possibility. of domestic sewer overflow into the stormwater channel entering' <br />the site. <br />The stormwater channel collects surface runoff from a newer, yet established, area of the <br />city. Because of the age of the development in the watershed, :there" is less likelihood of <br />areas that contain abandoned petroleum products, stored or wasted sources of corrosion, ; <br />or historic underground. storage tanks that could contaminate soils and surface water' <br />runoff. "In -addition, the watershed is not dominated by heavy industrial facilities that <br />contain potential sources of stormwater contamination. A search through the Colorado <br />Department of Public Health and Environment Hazardous Materials and Waste <br />Management Division (HMWMD) database for solid and hazardous waste sites indicated <br />that none of these sites exist within the watershed-. Since the area is fairly established, <br />new construction and areas of potential increased erosion within the watershed are also <br />expected to be limited. <br />Construction of the stormwater channel will include structures and best management <br />practices that will minimize water quality impacts to the final groundwater lake. The <br />stormwater channel will be constructed at relatively shallow grades to reduce flow