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r <br />r <br />secured above ground to prevent backflow from ponded water. <br />D. Flushing shall continue until a minimum water volume of five times <br />the aggregate pipe volume has passed through the pipe section being <br />cleaned. The aggregate pipe volume shall include all pipe carrying flushing <br />water from the point of introduction to the work to the point(s) of discharge <br />from the run being cleaned. <br />E. Fire hydrants shall not be used as flushing discharge points. During <br />main flushing, all hydrant stab -out gate valves and water service curb <br />stops shall remain closed, Upon completion of main flushing, each <br />hydrant and service shall be opened and allowed to flush while the <br />;91 water source is being shut down. <br />F. For nominal pipe sizes of 6 inches and smaller, the pipe shall be <br />- flushed through a discharge extension of at least the full pipe diameter. For <br />nominal pipe sizes greater than 6 inches, a G inch diameter discharge <br />A extension pipe, connected to the work with reducer(s), may be used in lieu <br />p of a full diameter blowoff. <br />G. Flushing water shall be carried beyond the trench and shall be discharged in <br />a manner that will not cause erosion nor structural damage on or off-site. <br />and will not cause contravention of State water quality standards in <br />receiving surface waters. The Contractor shall provide adequate <br />extension pipe, sedimentation basin(s), and/or diffusion devices as <br />necessary to prevent such damage. <br />4. HYDROSTATIC LEAKAGE AND pRESSURE TESTING <br />A. Upon completion of flushing, the installed pipe system shall be tested <br />for tightness under a continuous hydrostatic gauge pressure of 150 psi, + <br />5 psi, determined at the lowest point in the system, for a period of 4 <br />hours. The allowable leakage rate shall not exceed that defined in and <br />specified by AWWA C600-82, unless otherwise requested by the Eng -sneer <br />prior to testing. <br />k. 2U-2 <br />k <br />B. If the work is subject to acceptance by a municipal or private utility with <br />its own adopted test requirements more stringent than those stated herein <br />with regardto pressure, duration, and/or allowable leakage rate, <br />such requirements shall supersede these specifications. <br />C. Testing shall be performed separately on each valved -off section of <br />the installed system. Testing shall be against closed in-line valves with <br />each valve in the system subject to the full test pressure differential for full <br />test time at least once during the course of testing. A short hydrant branch <br />may be tested as part of its corresponding run by leaving the gate valve <br />open and testing against the closed hydrant valve, for the full test period. <br />[' <br />Test pressure shall then be maintained while the gate valve is closed, the <br />! <br />hydrant valve opened, and a visual check made for leakage past the gate <br />valve, indicated by water rising in the hydrant barrel. <br />D. Allowable leakage shall be calculated based on the pipe diamcter(s) and <br />total laid length of the run being tested, with no additional allowance for <br />valves, fittings, or joints. No visible leakage shall be allowed. If <br />visible leakage is noted during the course of testing, or if allowable <br />leakage is exceeded, such leakage shall be repaired to the satisfaction <br />of the Engineer and the test repeated or extended for an additional <br />k. 2U-2 <br />k <br />