Agenda - 09-06-1994 - VIII-B - Laserfiche WebLink

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r- „s ,. ,' 13 ' PRELIMINARY DAM AND LAKE REPORT Lit Rhein Estate Property ' Orange County, NC Purpose ' The focus of this report is the existing dam and lake located on the Rhein estate property at the northwest quadrant of the Old N.C. Highway 10/Lawrence Road intersection, in central Orange County. The report's purpose is to report preliminary findings and provide preliminary recommendations regarding the dam's safety and long-term viability, both for the benefit of the general public and for the benefit of the affected property owners, or future property owners. Site Description The lake is approximately seven acres in size, and is fed by two intermittent streams, both f of which convey surface runoff from areas north and east of the lake. Both streams cross under Interstate 85 and drain significant areas between I-85 and Highway 70. The total drainage area to the lake is approximately 220 acres, and is generally in a low state of development density. The dam is parallel and adjacent to Old N.C. Highway 10, and is a few feet higher than the roadway embankment. The dam and lake are apparently several decades old, possibly as much as 50 years old. ' Site Inspection The dam appears to be about twelve feet high at its highest point. It generally appears to be well built, with adequate top width and acceptable slopes, although selected areas on the backslope appear to be sloughing or eroding somewhat. The top and backslope contain many trees of various sizes and species.. Most of these trees appear..healthy but a few are diseased or dead. The lake water level is about two feet below the top of the dam, except near the southeast end, where the top elevation of the dam appears to be about one-half foot lower than the rest of the dam. The front slope of the dam exhibits a fair amount of erosion in some areas, probably from wave action. The backslope and the area immediately below the dam do not show any unusual wetness that might indicate seepage, but the area is generally wet due to seasonal soil conditions. The site contains a very aggressive beaver population. Several beaver dams exist in the upper portions of the lake. The beavers have also been active around and below the dam, as evidenced by tree cutting, minor damming, well-defined trails, and fresh tracks. The most disturbing finding is the presence of two small holes about 5" - 6" in diameter, in the face of the ' dam, just above the water level, located near the northwest end of the dam. At the toe of the backslope, opposite these holes, appears to be a large ground opening, full of water, and well Page 1