Journal . In regard to the actual cost of pumping there is little tochoose between the two methods on the terms and conditionsexisting at Northwich. In fuel cost the advantage is withthe gas driven plant, but this is more than counterbalancedby the reduced capital cost of the electric plant and the factthat it is automatic in action. If gas driven ram pumps hadbeen installed capable of dealing with the quantities dealtwith by the electric pumps, they would have cost considerablymore and have necessitated the provision of a larger enginehouse and an extra attendant for night duty. Taking electr
Journal . In regard to the actual cost of pumping there is little tochoose between the two methods on the terms and conditionsexisting at Northwich. In fuel cost the advantage is withthe gas driven plant, but this is more than counterbalancedby the reduced capital cost of the electric plant and the factthat it is automatic in action. If gas driven ram pumps hadbeen installed capable of dealing with the quantities dealtwith by the electric pumps, they would have cost considerablymore and have necessitated the provision of a larger enginehouse and an extra attendant for night duty. Taking electriccurrent at the actual average pre-war price of 1 Jd. per unit andgas at 2s. 6d. per 1,000 eft., and the actual running tests of theplant, the comparative fuel costs work out as follows :—Electric pumps.—One pump raises and delivers 7,160 gallons against 80 ft. head in 10 minutes, consuming 4 units of electric current. ENLARGED DETAILS DRAWING Ne 5 River Crossings t^ :r 01 e r O A N t ^HBT f i 1 T~~ n. XORTHWICH SEWERAGE AND SEWAGE DISPOSAL WORKS. 231 d. Cost per 1,000 gallons raised 0-698 Gas-driven ram pumps.—One pump raises and delivers9,844 gallons against 80 ft. head in one hour, con-suming 162 of town gas. d. Cost per 1,000 gallons raised 0-494 In dry weather one electrically driven pump runs in theaggregate 3J hours in the 24, and pumps about 150,000 gallonsof screened sewage, and one ram pump working from half-an-hour to one hour pumps 5,000 to 10,000 gallons of unscreenedsewage. All the pumps deliver into one 12 in. rising mainwhich is syphoned under the old course (or backwater) of theriver Weaver across an island, and then syphoned under thenavigable (canalised) course of the river (see Fig. 4) and thenceup Spencer Street to Darwin Street, where it discharges intothe top end of the gravitating system of sewers, which conveysthe sewage to the Wallerscote outfall works. When the Sewers in the area FF, Fig. 1 were constructed,it was anticipated that the sew
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