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June 1955, a 14-month study was begun in Gorha , Me., on the maintenance of pipeline coefficients after cleaning with sodium hexametaphosphate. Gorham Village is one of the areas supplied by the Portland Water District. Because a large percentage of Gorham Village is above the gradient of Sebago Lake, the source of supply, a booster pump is needed to deliver water to the system. The booster pump is located at one end of the system, and a standpipe located at the opposite end floats on the system. The distance between the booster station and the standpipe is approximately 11,000 ft. The main feed from the booster station to the standpipe consists of an 8-in. pipeline with a small grid in the center of the system. A diagram of the system is shown in Fig. 1. The pumping facilities of the booster station consist of an electrically driven centrifugal pump with a capacity of 420 gpm, together with a centrifugal pump operated by a gasoline engine for use as a standby in case of power failure. The electrically driven pump, installed in 1918, had dropped in efficiency. The district was, therefore, interested in replacing this unit with a modern, more efficient pump. In investigating to obtain the information necessary to design a proper pump for this location, it was found that the coefficient C for the 8-in. line between the booster station and the standpipe varied from 50 to 56. Before proceeding it was felt that some action should be taken to reduce the head against which the pump would operate. Further study revealed that this 8-in. main between the booster station and |
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