accomplished in three lifts, and was completed on July 23, 1953. The interior walls and wood framing were given three coats of white vinyl resin paint. The panels, insulated deck, metal ladders, and brackets were fastened to the walls with lag screws and cinch anchors. All holes were drilled with star drills. Lumber used in the well was painted before and after installation. The exterior walls were dampproofed with two coats of asphalt emulsion, and 5 feet of zone 1 material backfill was placed around the building for frost protection. During the 1954 season, the embankment around the terminal well was completed to elevation 5407, about 1 foot above the terminal well insulated deck, or frost partition. During the 1955 construction season, backfill was completed to the top of the well. The concrete terminal well and roof were constructed in compliance with drawing 40-D-4664 (included as fig. 40). (b) Apparatus Installed by the Government.--All electrical connections, water tank, electric pump, sump pump, ventilator and transition were installed by Government forces in the locations shown on drawing 456-108-981*. The louver was placed ahead of the ventilator fan and installed to open inward. This was done to minimize pressure in the air vent and obtain maximum circulation. A 38-gallon square water tank, fabricated from 26-gage galvanized sheet steel, was fastened to the wall by means of strap iron and lag screws. Pressure from a 16foot head of water in the filling system burst the tank and it was replaced by a 30-gallon hot water tank. The electric pump could not be operated to reverse the flow to induce a vacuum on the manifold system. The piping system was therefore modified to incorporate reversing valves to obtain the required vacuum. Changes in the terminal well piping system to incorporate reversing valves are indicated on drawing 456-108-1112*. The 3-1/2-inch altitude gages were supplied by the manufacturer with the Bourdon tube element filled with a 50 percent ethylene glycol and water solution. Gages were sealed by the manufacturer with a rubber cap. Prior to installation, while checking equipment, it was discovered that the rubber cap seals were not effective, as the fluid had leaked from most of the gages. These gages were refilled by Government personnel using a 50 percent solution of a commercial ethylene glycol base antifreeze and the specific gravity aspirator to remove the air. During final installation of the gages it was necessary to refill 30 additional gages, as the solution leaked out of the rubber cap whenever one of the gages was turned on its side. The master gage arrived on the job during the fall of 1952, and while it did not meet specification requirements for size, it was accepted, since only one bid was received. It remained in storage until the leaks were discovered in the 3-1/2-inch altitude gages. While refilling the 3-1/2-inch gages, the master gage was attached to the system and found to be in error. The pressure side of the master gage checked, but the vacuum side was off. The gage was returned to the supplier who replaced the gage with a new 6inch gage meeting specifications requirements. 170. Flushing Piezometer Lines. - One 8-hour shift, 5 days per week, was employed to prepare the tips for service. The average time required, using the electric pump, was about 3 hours per tip. After the tips were in operation intermittent flushing was necessary to remove air from the tubes. No difficulties were encountered and excellent results were obtained with the electric pump. The first nine foundation tips were placed in service during June 1954, 37 additional tips during January 1955, and the remaining four tips during July 1955. During the latter part of the 1955 season, gage readings indicated the presence of air in some lines; so it was decided to reflush the entire system, using boiled water containing a commercial soap-detergent. This work was completed during January 1956. The air trap was calibrated and a measured quantity of water was pumped into each line. The return line connecting into the air trap was disconnected and all return flow was measured and wasted. A small quantity of fluorescent dye was pumped into each outlet tube using the hand pump, after which flushing was completed with the electric pump. Return of the dye proved beyond all doubt that a complete circuit had been made. *Not included. A complete circuit with dye return was recorded for 41 tips; a partial return of water but no dye was recorded for five tips; and no return was indicated for four tips. It is possible that, if pumping had been continued long enough, a dye return could have been accomplished in the five tips; but, since the intake was high and the discharge low, only a calculated quantity of water sufficient to flush each line was pumped. The same procedure was used for the tips where no return was recorded. Each line was flushed with a calculated quantity of water. 171. Pore Pressure Observations. Gage readings indicate that all tips in the system are working and register pressures which are correct. During embankment construction activities, 10-day pressure readings were transmitted to the Denver office. Thirty-day readings were transmitted during the winter or nonconstruction season. Tenday readings were submitted for all of 1956 and the spring of 1957, when the reservoir was being filled. 172. Embankment Control and Tests at Instrument Locations. - Backfill in piezometer trenches and over instrument locations was controlled by standard fill methods. Inspection personnel assigned to instrument installations devoted full time to supervision of backfill compaction. Soils which dried excessively were either reprocessed prior to compaction or were replaced by satisfactory materials borrowed from the rolled fill. Record test samples were obtained by laboratory technicians. Compaction and percolation-settlement tests were performed in the project field laboratory. Field densities were obtained by the sand method. Heavy, flat, steel plates were placed on the hand-trimmed compacted embankment. A circular hole in the plate afforded access to the embankment. Small hand tools were employed to excavate the density holes. Calibrated dry sand was introduced through a standard cone and valve. Nearby, heavy equipment traffic was stopped while the sand was flowing. Results of record tests are summarized in the "Final Report of Test Apparatus Installations--Palisades Dam," figures 4 through 7. Field moisture content of soils tested varied from 12. 5 to 18.2 percent. The average of 15. 4 percent was 0.9 percent drier than average laboratory optimum. Average field density is 5.2 pounds per cubic foot below maximum laboratory density. Field densities exceeded maximum laboratory densities in 21 percent of the tests performed, while fill densities exceeded cylinder densities in 65 percent of the tests. Percolation rates varied from 0.0185 to 1. 782 feet per year, while consolidation varied from 1.05 to 7.30 percent. Average consolidation due to loading was 4.42 percent, while consolidation due to loading and saturation average 4. 47 percent. Results of tests of zone 2 materials were not considered.in determining ranges and averages. 173. Cost of Piezometer Installations. The cost of the piezometer installa tions totals $38, 107.67, or a unit cost of $762. 15 per tip. This total includes materials, supervision and inspection, surveying, record testing and transportation. The itemized cost of the piezometer terminal well installations is as follows: Government Forces: Labor foreman, 39 hours at $3.03 Inspector, 31 hours at $2.73 Subtotal, Government forces Total installation costs in terminal well $118.17 $ 316.80 $2,202.57 174. Settlement Apparatus. - (a) Embankment Settlement Apparatus--Crossarms.-- The embankment settlement apparatus consists of one crossarm installation, located in the dam embankment at station 17+10 and 40 feet upstream from the dam axis, which extends from the bottom of the main cutoff trench to the top of the embankment. The crossarm interval is 10 feet. For details of the equipment see figure 41. (b) Surface Settlement Points.-- Specifications No. DC-3675 provided for installation of 34 permanent surface settlement points. Two of these points are located in the switchyard area and 32 are set on 200- or 400-foot centers along lines parallel to the dam axis, and at distances of 22 feet and 80 feet upstream, and 22 feet, 395 feet, and 810 feet downstream of the axis. Reinforcing steel rods, 5 feet in length, were utilized for the points. The rods were embedded in concrete collars which established bond with the adjoining fill. See figure 39. 175. Installation of Embankment Settlement Apparatus. - (a) General.-- Settlement apparatus was installed during daylight hours, when possible, to reduce difficulties of inspection and minimize working hazards. With the exception of the foundation crossarm, which was installed as described below, crossarm installations were located and excavated when the fill elevation reached a minimum of 3 feet above the new crossarm elevation. This arrangement provided adequate cover for the crossarm during rolling operations. The construction program was planned to permit the elevation of the area about the crossarm installation to be 1-1/2 to 2 feet above the rest of the fill when installation started. This procedure allowed embankment placing operations to proceed continuously without creating a low area in the fill. Excavation for the crossarm installations was by backhoe and by hand labor. Backfill was compacted by pavement breakers equipped with round tamping feet and by hand tampers. Installation methods similar to those presented in the Bureau's Earth Manual were followed as closely as practicable. (b) Crossarms.--The Andrew Well Drilling Co. drilled a 9-foot hole for the foundation crossarm, September 3, 1954. The pipe was installed, cement grout was placed around it, and the foundation crossarm was installed at elevation 5359.79. Elevation 5358. 17 is the measuring point. Zone 1 material was hand tamped around and above the crossarm with air tampers. Crossarm 2 and each succeeding crossarm was installed when the zone 1 embankment reached the designated elevation for crossarm installation. The final crossarm, crossarm 24, was installed October 24, 1956. (c) Surface Settlement Points.--No work was done on surface settlement point installation during 1954 or 1955. During 1956 three settlement points were installed at stations 20+00, 22+00, and 24+00, all 810 feet downstream from the axis of the dam. The installation of surface settlement points was completed in October 1957. Six points were installed 395 feet downstream from the axis and one point 810 feet downstream from the axis in June 1957. Because of construction activity on the riprap and cobble area, the installation of other points was held up until September and October 1957. Thirteen points were then installed 22 feet and 80 feet upstream from the axis and nine points were installed 22 feet downstream from the axis. Two points were installed in the switchyard, completing installation of all settlement points. The points on top of the dam 22 feet upstream and 22 feet downstream of the axis are protected with a 2- by 4-inch marker extending 6 feet above the surface to serve as a guide to snow plows pushing snow between the concrete guard posts. All points on the dam were installed as shown on figure 39. The location of the switchyard points was revised as shown on the as-built drawings. (d) Embankment Settlement Observations.--During embankment construction activities, settlement readings were recorded at the time of each crossarm installation, and were transmitted to the Denver office. Otherwise, 30-day readings were transmitted. When the final crossarm installation was made at the end of each construction season, backfilling was completed with the reading scale and adaptor attached to the top of the installation to permit observations to be continued during the winter without excavation. A small wooden shack was placed over the installation for protection of the installation and of observers during observation periods. When embankment placing was begun in the spring, the shack was removed and the normal installation procedure was resumed. 176. Reports. - Monthly progress reports were prepared by the engineers assigned to instrument installation. Estimate quantities were brought up to date each month and concurred in by the contractor's engineer. Record drawings were prepared as rapidly as the work to which they pertained was completed. Observation data were recorded on standard forms, typical examples of which are included in the "Final Report of Test Apparatus Installations --Palisades Dam, figures 1 through 3. Pore pressure observations, from readings on separate gages, were recorded on form 7-1346. Tip numbers and constants were added to transparent prints, as soon as all of the tips were installed, to facilitate field observations. Embankment settlement data were recorded on form 7-1348. 177. Cost of Installing Crossarms in Dam Embankment. The labor cost of installing crossarms in the dam embankment (item 188 of specifications No. DC-3675) was as follows: 178. Open-Cut Excavation. - The upstream portal area of the two tunnels is located at the base of the andesite mass which forms the left abutment of Palisades Dam. The portal area was excavated by open-cut methods until a suitable face was established for excavation by tunneling methods (fig. 146). Open-cut excavation was started on April 10, 1952. All brush and loose rock was removed from the slope in the vicinity of the portal prior to drilling. Because the hillside into which the portals were to be excavated was very steep, all drilling for blasting was done with jackhammers. After blasting, the material was removed with a 2-cubic-yard dragline and was used to form a dike between the portals and the river. During the first open-cut excavation, the floor of the portal approach was not brought to finished invert subgrade, but was excavated to the same grade as the tunnel foot blocks so as to provide access ramps for equipment which would be working inside the tunnel. Excavation of the invert was the final stage of tunneling operations. 179. Tunnel Excavation. - Excavation by tunneling methods began June 16, 1952, 183 days after receipt of notice to proceed (fig. 147). |