Agenda - 04-16-1985 - Laserfiche WebLink

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ORANGE COUNTY BOARD OF COMMISSIONERS Action Agenda ACTION AGENDA ITEM ABSTRACT Item It) Meeting Date: APRIL 16, 1985 SUBJECT: WATER USAGE IN COMPARISON TO STORAGE CAPACITY DEPARTMENT: COUNTY MANAGER PUBLIC HEARING: Yes X No ATIPauctu(S) : INFORMATION CONTACT: MANAGER'S OFFICE X 501 TELEPHONE NUMBER: Hillsborough - 732-8181 YES Chapel Hill - 968-4501 Mebane - 227-2031 Durham - 688-7331 PURPOSE: Tb consider increasing water storage capacity at Lake Orange. NEED: Combined projected water usage within the Hillsborough Water System, the Cheeks Township portion of the Orange-A1amance Water System and the CWASA portion supplied through Hillsborough will exceed the capacity of the existing raw water impoundments by . the year 1994. Shortfalls in capacity occur even now when variations in average participation produce dry seasons. One recourse is to add additional raw water impoundment capacity. While Hillsborough (Lake Ben Johnson) and the MASA (Coffer Dam) are preparing for or taking action in this regard the measure first open to the County is to expand the back-up volume at Lake Orange. Factors to weigh are: (a) feasibility, (b) benefit, (c) construction cost, (d) land acquisition amount and cost, and (e) means of funding. Feasibility. Per preliminary study by Hazen and Sawyer it appears structurally and hydraulically feasible to raise the normal lake level 4 feet and still be within State and Federal design criteria. Benefit, Raising the lake by 4 feet would provide 65% additional raw water storage capacity (from 427 mg lake volume at normal, pool to 647 mg). Safe yield (20 year) would rise from 2.62 MGD to 3.10. fRnstractioaraaL Lake level would be raised by installing a rigid flashboard system across the present spillway crest at an estimated cost of $48,000.