JOINT WATER SUPPLY FOR FOUR TOWNS.
In the upper portion of Derbyshire, England, has been initiated a $50,000,000 waterworks scheme which is to supply four large towns, each situated in a separate county. The watershed to be drawn upon lies in the valley of the river Derwent and embraces the whole of the valley.
It being found necessary to provide a new supplementary source of supply for the towns of Derby and Leicester, this valley was selected for the purpose. As soon as the intention to utilise this watershed become public, the towns of Nottingham and Sheffield put in their claim to share in the privilege, and, after $500,000 had been spent in preliminary surveys and a campaign in Parliament, the result was the formation of the Derwent Valley Water Board, representing Nottingham, Leicester, Derby, and Sheffield, the first three towns in the counties of the same name and distant respectively from the proposed source of water supply thirty, thirty-five, and fifty miles respectively, while Sheffield, the Yorkshire town, is distant only ten miles. The board was authorised to acquire the water rights covering an area of fifty square miles in the valleys of the Derwent and the Ashop, and to construct reservoirs and other works there at an estimated cost of $50,000,000. The water resources to be brought to the service of these towns are practically inexhaustible. The gathering ground has an elevation above sea-level varying from 500 to 2,070 feet. The annual rainfall is copious. An estimate based on dry year averages shows that a minimum of fifty inches per annum may he relied upon. This will yield for storage 50,000,000 gallons per day. The whole of this volume of water will not, of course, be available for consumption; one-third must he restored to the Derwent at a point below the reservoir system, to prevent injury to the vested interests in, and along the stream. The quantity left for consumption will he shared as follows; Leicester. 35.72 per cent.; Sheffield and Derby, twenty-five per cent, each: and Nottingham. 14.28 per cent. These proportions are not based on population, but on the need of increasing present supplies. The cost of the works will be borne in the same proportions. There will be five reservoirs of respective dimensions as follows: (1) Storage capacity of 1,886,000,000 gallons, with a dam 114 feet high and 1,080 feet long; (2) capacity of 2,495,000.000 gallons, with a dam 113 feet high and 1,080 feet long; (3) capacity, 2,495,000,000 gallons, with a dam ninety-five feet high and 1.950 feet long; (4) capacity of 1,472,000,000 gallons, with a dam 103 feet high and 840 feet long; (5) capacity of 2,160.000.000 gallons, with a dam 136 feet high and 980 feet long. All the water collected in these reservoirs must he filtered, and filtering beds covering an area of fourteen acres will be made. The five dams will need 2.000,000 tons of stone, and quarries covering fiftytwo acres have been bought in the neighborhood. The machinery used (the Lidgervvood overhead cable) can deal with masses weighing up to six tons, and many blocks put into the dams will be of that size. The work will be completed in twelve years.