Of the 558 piles to be driven inclusive of the two T piles and the two D-12 piles, 526 piles were driven to full or partial depth. This involved a total of 6, 942 linear feet of piling at an average depth of 13. 2 feet. It was possible to reuse the cut lengths of many piles that were only driven to a short depth. Actually, only 10 full-length piles were driven. The last pile, No. 353 on the right wing wall, was driven on November 4, 1948. The contractor's bid price for driving the estimated 600, 000 pounds of sheet steel piling listed in specifications No. 1410 was 2.0 cents per pound. Only 250, 368 pounds of piling were driven. The contractor maintained that his moving-in cost and unit equipment cost for this lesser amount of steel was excessive and that certain adjustments should be made. Order for changes No. 7 recognized these costs and allotted $5, 734. 11 for hauling, handling, preparatory work, and making driving setup for the 349, 632 pounds of piles that were not driven. This change increased the cost of driving to slightly less than 4.3 cents per pound.

111. Relocation of State Highway No. 61. The earthwork for the relocation of Nebraska State Highway No. 61 was completed, for the most part, during 1947. The culverts were installed along with the earthwork, but the concrete head walls were not placed until July and August of 1949. During the summer of 1949, the contractor opened a quarry on the right bank of the river upstream from the spillway to produce the crushed rock required for the 12-inch gravel blanket under the riprap on the upstream slope of the dam embankment (sec. 99). Screenings from the quarry operation were used as surfacing material for the relocation of State Highway No. 61. These screenings packed well and produced a highly satisfactory road surface. As portions of the roadway were brought to final grade and bladed to an even surface, guardrail post holes were drilled with an earth auger, and guardrails were placed on the dam and dike embankments and on the highway fills. Placing and painting of the guardrails were completed on December 31, 1949. A section of the completed highway is shown in figure 59.

112. Miscellaneous Force Account Work. - Miscellaneous force account work was performed by Government forces during the construction of Enders Dam. During October and November of 1949, grading equipment furnished by the Kansas River district was used to grade an access road in the vicinity of the caretaker's residence southeast of the spillway stilling basin, and to grade a bathing beach in the area north of the dam. The beach was proposed for recreational development in a plan prepared by the National Park Service. Grading for the beach was done so as to have the work completed prior to the storage of water in the reservoir.

During October, November, and December of 1949, Government forces placed a protective blanket of sandy Ogallala material from borrow pit A-1 and from required spillway excavation on portions of the slopes of the abutment cutoff trench embankments to protect the slopes from erosion. Some native rock for riprap was also collected in the vicinity of the dam and placed by Government forces.

A Quonset-type building that was used at the dam site as a garage during the construction period was dismantled and re-erected in 1949 by Government forces on a foundation built as a part of the contract for the caretaker's residence and maintenance facilities. A similar Quonset building was used as a garage and warehouse at the Government residential camp at Imperial. The portion used as a garage was dismantled and shipped to Trenton, Nebr., for use by the Bureau of Reclamation there. The portion used as a warehouse was dismantled in January 1950 and used to complete the building near the caretaker's residence.

113. Contract for Completion of Enders Dam. - Work was started on the contract for the completion of Enders Dam, under specifications No. 3076, on July 22, 1950. The principal items of work to be performed under this contract included the erection of four 50- by 30-foot radial gates of the same size for the spillway; the completion of the installation of a large part of the electrical and mechanical control apparatus used in operating the gates, including portions of the radial gate hoists; the installation, in the spillway gate structure, of an electrical transformer and electrical distribution system, together with the motor-generator set, battery charger, and 60-cell storage battery; the installation of that portion of the ice prevention air system distribution piping located in the compressor room of the spillway gate structure, including the air compressor;

Figure 60.--Supply pond for rotary drilling rig at drainage well No. 3. The discharge from the drill is shown at the lower right. P328-701-5079, September 9, 1953.

the placement of the concrete plug in the outlet works trashrack structure; the completion of the hydraulic gate hanger assembly for the outlet works high-pressure gate installation; the installation of two 60-inch hollow-jet valves in the outlet works valve house; the placement of concrete for equipment pedestals and minor miscellaneous concrete repairs; the final setting, adjusting, and operating of all mechanical and electrical equipment; and the placing of uncompacted fill in the channel upstream from the trashrack structure after the closure of the stream.

The contractor for the completion of Enders Dam, Claussen-Olsen- Benner, Inc., subcontracted the major items of work. The steel erection was sublet to Harris and Meyer, Inc., of Bellevue, Nebr. ; the sandblasting and painting of the radial gates was sublet to the B. C. Ohe Co., Omaha, Nebr.; and the electrical and mechanical installations were sublet to Priesner Electric and Plumbing Co., Ogallala, Nebr. Other items of work, namely the concrete work, the earth work, the installation of the hollowjet valves, the completion of the high-pressure gate assembly, and the testing and adjusting, were performed by Claussen-Olsen-Benner, Inc.

The specifications provided that on October 1, 1950, the contractor would be permitted to interrupt the flow of the river to permit closure of the temporary entrance to the outlet works. The contractor scheduled October 5 as the date for this operation. However, the Frenchman Valley Irrigation District was carrying on a program of fall irrigation, and the Bureau of Reclamation was unable to obtain the district's approval of the date for river closure; therefore, it was necessary to direct the contractor to defer the date for stopping the flow of the river. Final closure and the beginning of water storage were effected at Enders Dam on October 24, 1950.

The contractor exceeded the contract completion date by 18 days, and all work under the contract was completed and accepted as of January 6, 1951. The contractor executed the final payment voucher and the release of contract on January 25, 1951. No exceptions were included on the release.

114. Drainage Wells and Test Shafts. The design and function of the drainage wells and test shafts are discussed in sections 23 and 28. The drainage wells and test shafts were constructed after completion of the dam and filling of the reservoir, under specifications No. 3693 (contract No. 12r-19789) by the Layne-Western Co., Omaha, Nebr., for a contract price of $16, 048. The contractor acknowledged receipt of notice to proceed on April 21, 1952, and by terms of the contract the work was scheduled for completion on July 20, 1952.

The contractor started moving in and setting up his equipment on May 7, 1952. The contractor experienced difficulty in unwatering the site of test shaft No. 1 because of an adverse grade in the 8-inch-diameter drain. Because of this and extra work for construction of drainage well No. 2, the contract time was extended 40 days, or to August 29, 1952. All work was completed and accepted on August 25, 1952, which was 4 days ahead of the new completion date.

The location and details of the drainage wells are shown on figures 7, 8, and 10. The contractor started work on drainage well No. 1 on May 9, 1952. The drainage wells were excavated with a small orange-peel bucket which was suspended from a pipe A-frame and operated with a gasoline-powered double-drum hoist. The wells were cased as the excavation progressed. This was done by forcing the casing down by a jacking arrangement that was anchored to deadmen on opposite sides of the well. The temporary casing for well No. 1 consisted of a 42-inch inside-diameter casing for the first 14 feet and a 38-inch inside-diameter casing for the remaining feet. For well No. 2, the inside diameter of the temporary casing used was 54 inches for the first 10 feet, 42 inches for the next 15 feet, and 38 inches for the remaining 35 feet.

The permanent casing used in the drainage wells was 24-inch inside-diameter, 14-gage metal well casing. It was supplied in 4-foot lengths and was riveted on the site. The joints in the casing were riveted butt joints with 4-inch reinforcing bands. All casing used below the ground-water table was standard perforated well casing. To insure a uniform gravel pack around the well casing, three metal brackets were bolted to the

vostow perforated section, equally spaced around the outside of the casing. As the 24Jet cotng was lowered into position, it was perfectly cemered inside the temporary 28-inch casing, which the contractor piled as the gravel packing was placed. The bottom of the 38-inch casing was kept a minimum of 18 inches below the gravel. The gravel was obtained from a commercial source at Ogallala, Nebr. It was reasonably well graded and clear, with 95.5 percent of the material passing the 3/4-inch screen and 27 percem passing the 3, 16-inch screen. Sixty-five percent of the latter size was retained on the No. 8 screen.

The location and details of the test shafts are also shown on figure 10. The contractor started excavation of test shaft No. 2 on May 19, 1952, using the orange-peel bucket and hoist arrangement. The shaft was cased with 54-inch inside-diameter, extrastrong, reinforced concrete pipe as the excavation progressed. Excavation for the first 3 to 10 feet was in zone 3 material containing large chunks of cemented Ogallala sand. These chunks made it difficult to excavate the shaft to the correct size and alinement. As soon as the excavation had progressed 5 or 6 feet, the concrete casing was lowered by means of a steel collar around its lower end. Four equally spaced points of support were located around the collar just inside the casing, to which cables were attached. With this arrangement, the contractor could keep the casing plumb by varying the tension on the cables. The bottom of the casing was supported approximately 1 foot above the excava

tion.

An investigation disclosed that the 8-inch concrete pipe drain that was to drain test shaft No. 2 (fig. 10) was crushed approximately 10 feet from the inlet, and there was no evidence of water having flowed through the drain. Order for changes No. 1 was therefore issued which directed the contractor to plug the 8-inch concrete pipe drain with concrete, to remove the concrete pipe casing from test shaft No. 2, and to backfill the test shaft with compacted material. Compaction of the material was obtained by dropping a 4-1/2-inch-diameter by 92-inch steel shaft a distance of 18 to 24 inches.

Excavation of test shaft No. 1 was started the last of May and was completed the latter part of August. The test shaft is located 190 feet downstream from the axis at station 43+53, approximately in the center of a 12-foot-diameter slump area. The test shaft was placed in this area to provide data regarding the cause of the settlement. The contractor experienced difficulty in unwatering the site of the test shaft because of the adverse grade in the 8-inch drain. As a result, the observational tests were interrupted several times. The contractor employed three unwatering wells and a sump pump within the shaft before the water was controlled. Excavation proceeded slowly as there was considerable caving of the dry sand and rocks around the concrete casing. Most of the caving occurred on the north and east side, forcing the concrete out of plumb. The bottom excavation was done by hand. The test shaft was excavated to a depth of 33 feet, and the bottom of the 54-inch casing was located at elevation 3038.4. The extra work associated with test shaft No. 1 was performed under order for changes No. 1.

115. Auxiliary Drainage. Auxiliary drainage, consisting of two additional drainage wells and the left abutment drain, was constructed at Enders Dam under specifications No. DC-3967, about 2-1/2 years after storage began. Claussen-OlsenBenner, Inc., Holdrege, Nebr., was awarded contract No. 14-06-D-510 on their low bid of $27, 580. The contractor acknowledged receipt of notice to proceed on July 22, 1953. Drainage wells No. 3 and 4 were scheduled for completion by August 20, 1953, and the remainder of the work was scheduled for completion by October 20, 1953.

Delays occurred in the fabrication of the 24-inch casing for the drainage wells, and further delay due to late delivery of a drill rig to a subcontractor who was engaged for the actual drilling operation. As a result, both wells were not considered to be completed functionally until September 15, 1953, when there remained only the installaion of the anodes and a small amount of leveling at that date. The contractor was assessed a penalty of $500 in liquidated damages because completion was 25 days beyond the specified completion date for the drainage wells. Unwatering for the abutment drain was started on September 16, 1953. Work progressed satisfactorily on this phase, and the entire project was considered complete on October 15, 1953, 5 days ahead of the scheduled completion date for the contract.

Drainage well No. 4 was drilled first. Work began by excavating with a dragline to a depth of about 5 feet, placing an 8-foot section of 42-inch-diameter casing, and backfilling with impervious material to the top of the casing. The well was drilled through this casing with a 39-inch-diameter cutting bit. The reverse rotary method was used, in which cuttings were pumped out through the drill stem and discharged into a supply pond as shown in figure 60. The cuttings settled-out in the pond, and the water was returned in a fairly clear condition to the drill hole. At the start of the drilling operations for this well, a large boulder, evidently deposited during wasting operations, was encountered at a depth of 6 feet. The boulder was of a composition for which the drill was not designed, and was loosely deposited, resulting in considerable vibration in the vicinity of the embedded casing. The boulder was eventually penetrated, and drilling proceeded satisfactorily thereafter. In the sand and gravel strata, the drilling rate was approximately 1 foot per minute.

In order to center the permanent 24-inch steel casing in the drill hole, three steel bands were bolted to the periphery of the casing about 10 feet from the bottom as shown in figure 61. The casing was then placed in the drill hole, plumbed from the top, and secured in position to the drill rig. The drill hole was considerably larger than the minimum 36-inch diameter, and the minimum sand-gravel pack of 6 inches around the 24-inch casing was exceeded without exception. Sand-gravel filter material was placed by means of 5-inch-diameter jointed pipes, which were raised as the material was placed. The filter material was rodded by a 1-inch jointed pipe raised and lowered with a dragline; this material was placed to within 2 feet of the ground surface (fig. 62). At the completion of the placing of the filter material, it was found that approximately 1.5 cubic yards of the finer material had been forced through the perforations in the 24-inch well casing. (Gradation tests on the filter material showed approximately 70 percent finer than the 3/16-inch perforations.) The material inside the casing was removed by means of a sand bucket. After the 24-inch casing had been cleaned, a sand-bentonite seal, consisting of 120 pounds of granular bentonite and 1,020 pounds of fine sand, was placed around the plain casing in the upper 2 feet of the well. The seal was placed before the removal of the 42-inch temporary casing and was of more than the required 6-inch minimum thickness. The 42-inch casing was then pulled from the upper part of the well.

The drill rig was moved to the site of drainage well No. 3 on September 4, 1953, and set up preparatory to drilling. When the supply pond was filled with water, the water immediately started to leak into the flat below the well, and the casing started to cave, apparently as a result of collapsing of the voids between large boulders that had been placed at this point during wasting operations. It was decided to move the site of drainage well No. 3 about 20 feet north of the original location, where it appeared that any large boulders present would be encountered within the length of the blind portion of the casing. Accordingly, the drill rig was set up on the new location, station 52+00, 220 feet downstream from the dam axis, and drilling was started. Drilling progressed satisfactorily until red sandstone was encountered at a depth of 54 feet, which slowed the rate of drilling almost to a halt. A 30-inch diameter special rock-cutting bit was obtained and was successful in completing the hole to the required depth of 62 feet.

Before the permanent casing was installed, the bottom 10-foot section was changed to 7-1/2 feet of 18-inch casing welded to a 2-1/2-foot transition section between the two sizes of casing. The casing was placed and centered in the hole, and filter material placed around it in the same manner as for drainage well No. 4. Approximately 15 cubic yards of filter material were used, of which approximately 1-1/4 cubic yards were removed from inside the casing by sand bucketing operations. The sand-bentonite seal was placed around the top 2 feet of the plain casing, and the temporary casing was pulled.

The connecting ditch between drainage wells No. 3 and 4 was dug with a dragline, and the 10-inch clay tile outlets were installed according to specifications. A concrete plug was also placed in the bottom of each well. At each well, the external anodes were placed 180° apart, 10 feet from the edge of the well and 10 feet below the ground surface. The internal anodes were suspended from a rod in the center of each