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3.5 Physical Environment <br /> 3.5.1 Existing Water Quality <br /> This project is located within the Phil's Creek sub-basin of the University Lake Watershed, a <br /> designated water supply watershed (Figure 1.2). <br /> The quarry operation uses process water to wash certain sizes of its product. This water is <br /> pumped from the third settling pond (as shown on Figure 3.7) to the wash screen. Water from <br /> this pond is also used for dust suppression at the plant. <br /> From the wash screen the water enters the first of the three settling ponds where the majority of <br /> the solids settle out. From that pond it flows to the second pond for further settling, and finally <br /> to the third pond for storage and reuse. Water in the third pond is clear and free from suspended <br /> solids. This process water is not discharged at all, but kept in a closed circuit. As needed, solids <br /> are removed from the first settling pond by dragline. <br /> The quarry also pumps water from the pit, particularly during periods of heavy rainfall. This water, <br /> which is mostly rain water and partially ground water, flows to a sump settling pond before it is <br /> pumped either directly into Phil's Creek pursuant to the General Permit or to the third settling <br /> pond for use in the plant process. <br /> University Lake and Cane Creek Reservoir are the primary sources of water supply to the Chapel <br /> Hill-Carrboro urban area. The OWASA Quarry Reservoir at the project site serves as <br /> supplemental raw water storage of 200 million gallons which can be released to University Lake <br /> via Phil's Creek. Protection of both the quantity and quality of surface water and groundwater <br /> supplies within the University Lake Watershed is essential for provision of adequate supplies of <br /> good quality drinking water. <br /> A. Surface Water Quality <br /> The waters of the river basins of the State of North Carolina are classified "based upon the <br /> existing or contemplated best usage of the various streams and segments of streams in the <br /> basin". The water quality classifications for fresh waters in North Carolina are listed in Table 3.5. <br /> 3-12 <br /> • <br />