OCR

1945 Norfork Dam - This project was designed by the Army Corps of Engineers for flood control and was jointly sponsored by Morris on-Knudsen and Utah with Morris on-Knudsen men in charge. A straight gravity concrete structure, 222 feet high and 2, 624 feet long, the dam is located in north-central Arkansas on the Northfork River which is part of the White River. The Northfork, long noted for its sudden and disastrous floods, was diverted in three stages by earth dikes, cribbing and cofferdams. Two 1 0-ton Lidger- wood cableways, each with a span of 2, 835 feet, were set up to place the 1,533,245 cubic yards of concrete in the dam and powerhouse. The job started in April, 1941. War came with the year's end, and in September, 1942, the project was reorganized to produce early electricity for strategic metal pro- duction in Arkansas. A rush-order power plant was added to the plans. With the over -all speed-up brought by the power house, concrete placement from the cableways was stepped up 60 percent by hauling concrete over a truck ramp to a pouring area in fast, three-yard Koehring Dumptor trucks, transferring it to a shuttle car which alternately filled two cableway buckets in rapid succession. A series of flash floods destroyed the truck ramp, but not before it had largely served its purpose, Special care was taken in the handling of the leanest mix of concrete ever poured into a dam up to that time. Near-freezing water from an ice plant was pumped through a network of steel pipes in the dam to cool the concrete which generates tremendous heat in its settlement. In hot summer crushed ice was used in the concrete mix to keep the temperature as low as possible. During the Christmas season of 1942, a 34-foot flood, the next to the highest ever recorded for the Northfork River by the U. S. Army Corps of Engineers, rose from heavy rains in five hours. Water pouring over the cofferdams swirled through the work area and destroyed a low-water bridge. Debris swept against the work trestle, twisting and damaging the steel girders. In may of the next year an even more destructive flood covered the dam site. Although the partially completed structure protected much valuable downstream farmland, many days of construction time were lost. One generator producing 35, 000 kilowatts was installed in 1944 with provision made for three future generators in the same structure. The dam makes a lake 40 miles long, holding 1,983,000 acre -feet of water to generate this electric power, in addition to stopping the floods of the once destructive Northfork River.