crushed material which in combination with the relatively high percentage of No. 4 material resulted in a well-graded material that formed a stable ballast section.

A subcontractor hauled the ballast to the right of way. The initial 3-inch-thick ballast course was placed by the use of a spreader box attached to dump trucks which unloaded the material to the subgrade. Ballast material to complete the ballasting of the relocation was stockpiled along the right of way near the east end of the relocation,

Another company subcontracted the track building feature of the relocation. Local labor supply was limited to men who were agricultural workers. A crew comprised of about 20 of these workers was supplemented by a skilled crane operator and several experienced track workers. Track laying operations began north of Muskrat Creek and progressed northward. The contractor's equipment included a motor-propelled, standardgage rail crane capable of handling and placing the 90-pound rail.

Tracklaying operations were expedited by the use of the crane and air-powered track tools. When tracklaying operations were completed to beyond the vicinity of the ballast stockpile, railroad ballast cars especially designed for track ballasting were loaded with ballast utilizing a portable conveyor-type loader. A crawler-type tractor, adapted to standard-gage railroad, was used to deliver and distribute the ballast to the desired location.

Final track surfacing operations, which followed the distribution of ballast, brought the trackage to completion. A very satisfactory track surfacing job was performed by the use of air-driven tampers. Operations bringing the trackage to grade and alinement were of a routine nature. Motor car set-offs were completed late in June and the relocated line was placed in use immediately thereafter.

129. Other Construction Work. - The telegraph line and right-of-way fence construction were subcontracted. Telegraph line materials were furnished and delivered to the job site by the Government. Poles, copper wire, and steel wire used in construction of the relocated telegraph line were salvaged from abandoned lines within the reservoir area. Fencing materials were new and were furnished by the contractor.

The subcontractor on the telegraph line was assisted by linemen from the company interested in the line, and by representatives of the railroad company. A very acceptable communication line was obtained.

The right-of-way fencing entailed the use of barbed wire attached to steel posts with timber brace panels installed at frequent intervals. The subcontractor was skilled in fence construction and built a good fence in record time. This feature was completed about mid-July and concluded the work under the contract.

130. Salvage of Materials. After the prime contractor had completed his work, the railway company salvaged the abandoned Muskrat Creek bridge and the trackage beyond the bridge. During the spring of 1953, a contract was awarded for salvaging the abandoned portion of the railroad and its related facilities. Under the terms of the contract, the ownership of the rail, which was stockpiled near the south end of the relocation, was retained by the Government. The ownership of all other salvaged materials reverted to the contractor in payment for his work in clearing up the abandoned right-of-way.

CHAPTER XVII--PRELIMINARY CONSTRUCTION-

DAM AND POWERPLANT

A. Diversion and Clearing

131. Diversion and Care of the River. The diversion works are discussed in Chapter VI. The elevation of the invert of the diversion tunnel and the elevation of the diversion inlet channel were at such a low level that it required very little placement of earth in the river to divert the water through the tunnel. As soon as the diversion tunnel and the spillway stilling basin were completed, the diversion inlet channel was opened and the river flow was diverted. The diversion tunnel was completed in November 1949 and on December 23 the river was diverted.

The main cofferdam was constructed to elevation 4660 and was later incorporated as the upstream toe of the main dam. After the earthwork and foundation grouting had been completed and the outlet works was completed, the diversion tunnel (fig. 55) was closed off during October 1951 thus starting storage in Boysen Reservoir. A 36inch bypass pipe was installed in the diversion tunnel, prior to the closing, to allow a minimum flow downstream for the needs of water users below the dam. As soon as storage reached the level of the outlet works, releases were made through them and the bypass pipe was closed.

132. Clearing Operations.

Clearing of Boysen Reservoir was accomplished under a total of seven contracts. There were nine areas cleared, totaling 12, 722 acres. The total contract costs amounted to $627, 136. Detailed data for the various clearing contracts are given in Chapter XII. A map of the clearing areas is shown as figure 56. All clearing contracts were completed in the time allowed by the specifications. Early closure of the diversion tunnel caused filling of the reservoir ahead of schedule and kept one contractor busy to finish clearing his area before it was flooded out by the rising water in the reservoir.

Some standing live trees were left in the lower elevations of the reservoir. It was assumed that they would become waterlogged and eventually fall over and remain in the bottom of the reservoir. Other trees were only topped and the trunks left standing. Small willows, sagebrush, and greasewood less than 2 inches in diameter were not required to be cleared. Thirty-thousand logs, between 4 and 12 inches in diameter, were trimmed and stockpiled for use in the Bureau erosion control work on Fivemile Creek, a tributary to the reservoir. The remainder of the timber, consisting primarily of cottonwood trees, had no commercial value.

A newly developed tree cutter mounted on a dozer blade greatly simplified clearing operations. It was built and operated by the first contractor but the other contractors quickly built similar units. The tree cutter (fig. 57) consisted of a triangularshaped blade approximately 6 feet long with large saw teeth mounted on two edges. To cut the trees, the tractor operator steered the point of the cutter near the base of the tree. As the tractor moved forward the tree was sheared off by the saw teeth. Cottonwood trees up to 24 inches in diameter were cut with a single pass. One operator could fell approximately 5 acres of dense timber in 8 hours. The type of terrain and the timber, in the relatively flat botton land along the river, were well suited for operation of these tree cutters. Their use speeded up clearing operations and resulted in low bids for clearing the reservoir. Other pieces of equipment employed by various contractors were heavy rake teeth attached to a dozer blade, used for piling brush; and a mower and rake used for cutting and piling willows and light brush. Miscellaneous equipment in use by most contractors included trucks, pickups, welders, caterpillar-type tractors with dozers, various sizes of chain saws, circular saws, and motor patrols.

B. Excavation

133. Dam Foundation.

- In general, stripping consisted of removing the overburden from the entire embankment foundation to the limit of root growth. In addition to the overall stripping, the overburden was removed to comparatively solid rock, or where the bedrock could be stabilized by grouting.

Stripping for the cutoff wall began in January 1949. It extended some 50 feet each side of the cutoff wall, with the exception of the area of the river channel,