THE NEW DAM AT FORT WORTH
The completion of the West Fork Dam of the Fort Worth, Tex., water system, on the Trinity River, means a largely increased water supply affording an abundance of water for the city’s manufacturing needs. Fort Worth has drawn its water supply from the Paluxy and Trinity sands of the upper cretaceous formation by deep wells, the Paluxy sands being reached at a depth of 160 to 200 feet in the low lands along the Trinity River, and the Trinity sands at the deptli of 900 to 1,000 feet. A limited quantity of water is drawn from the Glen Rose sands, lying between the others named, where the casings are perforated. Supplementing the artesian water supply the city water works department has three small masonry dams in the channel of the Clear Fork, which joins the West Fork of the Trinity River at Fort Worth, these dams being one, six and eight miles west of the city, respectively. All of the city wells and some of the private wells, of which there are about 250 tapping the same sands, arc pumped by direct air lift, this entailing a great expense. Municipal well groups have furnished from 5,000,000 to 6,000,000 gallons of water daily and the probable supply from the private wells is about the same quantity. With a view to economy and insuring a permanent supply of water, that should provide for the present and forecast as far as possible the future demands, the city government, in 1910, ordered a comprehensive survey of the water supply conditions by a board of engineers. Early in 1911 the board recommended an impounding and storage reservoir on the West Fork, the main branch of the Trinity, the site of the dam being six miles, air line, from the city, with a drainage area above the dam site of 1,800 square miles. Mr. Hawley in a minority report advocated a reservoir on the Clear Fork. Upon the adoption of the majority report the same board of engineers was retained to design and supervise the construction of the reservoir and its appurtenances. Work was begun under contract by a construction company in November, 1911. In April, 1913, the city took it over, and the dam was completed by October, 1914. The earthen embankment portion of the dam is on a one on three slope on the water face and two on one on the other face, with a top 50 feet wide. The top of the embankment is 621 feet above sea level; the crest of the spillway is at an elevation of 609 feet, giving a free waterway of 12 by 700 feet. That is located on a rock base. All masonry is gravel concrete. The water face is partly riprapped and partly concrete lined. A reinforced concrete gravity conduit, 48 inches in diameter for three miles and 36 inches for three and a half miles delivers water to the filtration plant at the main pumping station plant. There are three special construction inverted river crossing syphons; conduit of the Parmlev type of reinforced concrete, four feet joints. The filtration plant was completed in January, 1912, and is in successful use whenever river water is supplied in the mains for domestic use in place of the artesian water. The length of dam is 3,370 feet, of which 724 feet is concrete; height of dam 74 feet, acres covered, over 4,000; cost, completed, including the conduit, will be all of $1,500,000. Concrete wings protect the earthen portion of the dam and these extend 200 feet below the dam to obviate danger of undermining by backwash or eddies. The outline of the shore of the reservoir, which has been named Lake Worth, is irregular and the depth is variable with shelving banks in some places and precipitous banks in others. But few cross sections of the reservoir, above the dam, were made.