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The holes were backfilled after installation. All tips were connected with plastic tubes to gages in a terminal well at station 54+00, 183.5 feet downstream from the axis of the dam. A terminal well is shown in figure 38. Pressures in the embankment are transmitted from the tip through the water-filled plastic tubes, and observed on the gage.

62. Settlement Installations. - An embankment settlement system was installed in a test pit at station 53+00, 99 feet upstream from the dam axis. The lowest crossarm of the- system was placed on shale bedrock at about elevation 2649. Backfill was completed around the riser pipe from this crossarm at about elevation 2707, and nine additional crossarm units were placed at 5-foot intervals to the surface of the completed embankment.

Two standard-type foundation base plates (fig. 39) were installed at stations 15+00 and 21+00, 20 feet upstream from the axis, on the unconsolidated loessial foundation in the abutment of the dam. Also, four temporary plates, each consisting of a steel plate and riser pipe extending to the surface of the embankment, were installed at the following locations and elevations:


After the embankment had been completed above a plate, the plate was located by drilling and an access pipe was installed to the surface of the dam.

A total of 173 surface settlement points were installed at 200-foot intervals on the surface of the embankment and parallel to the dam axis (fig. 40). These points consist of 3/4- to 1-inch reinforcement bars ranging in length from 5 to 8 feet. These bars were driven flush with the ground surface and a concrete collar, approximately 15 inches thick and 15 inches in diameter, was placed around each bar within 3 inches from the top. As concrete was placed, the bars were alined and the upper end of each bar was center punched.

Shallow holes were drilled near the edges of the spillway floor slab and wall footing for use in determining elevations. The elevation of each hole was obtained by means of a level and leveling rod.

In the canal outlet works, a series of 3/8-inch-diameter brass bolts with round heads were placed at 25-foot stations in the invert for use in determining settlement. Vertical control was obtained with the aid of two permanent monuments located on the line center of the canal outlet works.


Cost summary:

(A cost breakdown for Trenton Dam and Reservoir and the railroad and highway relocations, as of August 28, 1957.)

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Major Construction Contracts

Item, contractor, and contract number

Foundation construction--Marshall, Haas and Royce, con-
tract I2r-18601

Construction of dam--United Concrete Pipe Corp., Vin-
nellCo., Inc., and Ralph A. Bell, contract I2r-19084

Earthwork and structures except bridge structures, re-
location of C. B. &Q. Railroad--Perry McGlone Const.
Co., contract I2r-19157

Superstructures for bridges, relocation of C. B. &Q.
Railroad--American Bridge Co., contract I2r-19183

Spillway chute modification--Cass Co., contract 14-06-

Constructing residence, combination garage and testing
laboratory, water and gas supply, and sewage disposal
systems for Government field construction facilities and
caretaker's residence—Northwest Realty Co., contract

Relocation of county road at Swanson Lake—Nichols Const.
Co., contract I103r-1582

Clearing Swanson Lake--Asbell Brothers Const. Co.,

Tree planting--Hitchcock County Soil Conservation Dis-
trict, contract I103r-1772

Planting trees and shrubs—Hitchcock County Soil Con-
servation District, contract 14-06-701-456

Stream gaging station, spillway channel--Rentior Co., Inc.
contract 14-06-701-1345

Subtotal, Major Construction Contracts

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APPENDIX A (Continued)
Minor Construction Contracts

Item and contractor

Reconstruct four signal mounds and construct an earth
cattle crossing on relocated C. B. &Q. Railroad, and
salvage 40" x 40" CMP and install at new location--
Perry McGlone Const. Co.

Preparation of site for tree and shrub planting, Swanson
Lake--A. H. Williams

Cultivation of trees and shrubs, Swanson Lake--Forrest

Summer fallowing of areas to be planted to trees. Swan-
son Lake--Forrest Quick

Preparation of replacement planting sites, Swanson
Lake--A. H. Williams

Preparation of cultivated land for tree planting, Swan-
son Lake--A. H. Williams

Summer fallowing tree sites, Swanson Lake—John D.

Electric power connection for irrigation outlet works,
Trenton Dam--McCook Public Power District

Painting interior of caretaker's residence--L. C. Brown

Preparation of tree planting sites, Swanson Lake--A. H.

Installation of automatic furnace blower unit on furnace
in caretaker's residence--Stratton Supply Co.

Construction of terraces, Swanson Lake--A. H. Williams

Construction of terraces, Swanson Lake--James W.

Subtotal, Minor Construction Contracts

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