3-11

Auxiliary electrical and mechanical systems

All auxiliary electrical and mechanical systems for the tidal powerhouse described in the IJC report of April 1961 were studied and estimated in detail. The systems for the present powerhouses are similar, and further detailed study is not warranted, since the overall estimates are quite accurately made by adjusting the previous estimate.

3-12 Main power transformers

At each powerhouse the generators would be combined in 5 groups of 10 each with a stepup transformer for each group. The transformers would all be three-phase, forced oil-air-type, delta-wye, rated at 111,100 kilovolt-amperes with BIL characteristics as described in the IJC report. At each powerhouse four transformers would have a high-voltage rating of 345 kilovolt and the fifth a rating of 230 kilovolt.

3-13 Station service

Station service electrical system for service areas would be taken from each of the five groups of generators by means of a 13.8-kilovolt feeder cable, when the powerhouse is in operation. The service for the aerial lines feeding the navigation locks and the tide gates, which form a part of the tidal power project, would be fed from a 13.8-kilovolt generator bus.

Inasmuch as the tidal powerplants will not operate continuously, it will be necessary to use power from the interconnected system for station service and auxiliary power when the tidal plants are not operating. The station service in each group of 10 units would be served by a 1,000-kilovolt-amperes, threephase, 13,200-480-volt transformer. Each transformer would be connected to a group bus which would furnish the auxiliary power to the 10 units connected to the bus. Each transformer would be capable of carrying the load of its group as well as that of an adjacent group.

3-14 Switchyard

The transmission lines in their entirety are included in the Department of the Interior report. Switchyard estimates were provided by the Bureau of Reclamation of the Department of the Interior and are included in the cost summaries of this report. The cost of main transformers is included with the powerhouse estimate, and the switchyard estimate, which had included it, is reduced by like amount in this report.

All metal in the water passageways, including the runner hub and turbine shaft, will have a minimum one-eighth inch stainless steel type 316 cladding, welded overlay or sleeves. It is noted that the International Passamaquoddy Engineering Board report of October 1959 contemplated that the turbine runner and certain other turbine parts would be fabricated of type 316 stainless steel. All estimates are based on the corrosion prevention coatings and cathodic protection systems recommended in the IJC report.

3-16 Fishways

At the request of the International Passamaquoddy Fisheries Board, fishways for anadromous fish were planned in the IJC report at the tidal powerhouse and emptying gates. In accordance with this request similar fishways have been provided at each end of powerhouse No. 1 and No. 2 with a collection gallery along the downstream side of each powerhouse. The fishway at the emptying gates at Pope Islet would be the same as shown in the IJC report.

3-17 Design

HEADRACE AND TAILRACE

The headrace channels were designed to minimize hydraulic losses without requiring excessive excavation. The bottom of the channel for powerhouse No. 1 varies from elevation -44 at the entrance, to elevation -50 at the narrowest part of the channel and to elevation -40.7 at the powerhouse. The bottom of the headrace channel for powerhouse No. 2 is level at elevation —40.7.

The bottoms of the tailrace channels for both powerhouses vary from elevation -67 at the powerhouse to about elevation -35 in Cobscook Bay. Average velocities in the headrace channels would be about 3.5 feet per second and in the tailrace channels about 3 feet per second.

The part of the excavation of the channels above high tide would be used for cofferdams. Cofferdams would be constructed, the work areas in the channels unwatered, and the work continued in the dry. It is planned to use the material excavated from the channels for powerhouse No. 1 in the permanent features of the project. Since construction of powerhouse No. 2 will be scheduled in the last phase of development, only a small portion of the material excavated from the channels could be used; the remainder would be wasted.

3-19 Cofferdams

In estimating the cost of cofferdams the same design is used as in the IJC report. The quantities of materials vary with the number of units, 30, 50, 70, or 100, to be installed. Sources of materials for cofferdams also vary, being dependent upon what materials would be available in the early stages of construction. The length of cofferdams at powerhouse No. 2 exceed those of powerhouse No. 1 because of greater distances between suitable abutments.

3-20 Service facilities

MISCELLANEOUS ITEMS

The service facilities consist of maintenance shops, warehouse, utilities, land plant, floating plant, housing facilities, parking areas, service and access roads, and an access railroad spur to each powerhouse. The warehouse and storage area would be at Carryingplace Cove as in the IJC report.

3-21 Relocations

All public and private facilities interrupted by the proposed construction would be relocated to give the same service as before the project was started. The costs of the work necessary to make the owners whole would be included as project costs in accordance with established procedures. These costs for powerhouse No. 1 are increased from the IJC report for the extension to a wider headrace. The same bridge is used as the one in the IJC report for carrying the following facilities across the channel into Eastport; State Highway Route 190; a single track branch line of the Maine Central Railroad; the water supply line to the city of Eastport; two power circuits of the Bangor Hydroelectric Co. 1 cable and 22 wires of the New England Telephone & Telegraph Co.; and Western Union communication wires.

The wider headrace for the waterway to powerhouse No. 1 requires removal of the sides of Kendall Head on the westerly side and Redoubt Hill on the eastern side. This would cut off the roads leading to the houses on the top of the two hills. Relocation of the access and utilities to both areas is included in the plans and cost estimates.

The same highway, railroad, and utilities would require relocation across the headrace of powerhouse No. 2 by means of a bridge similar to that across the headrace of powerhouse No. 1. The crossing of the water pipeline to Eastport is at Bar Harbor and along the line of the powerhouse. Since the relocation would not be completed before the construction for powerhouse No. 2 is started, a temporary waterline would be required prior to construction of the permanent replacement.

The real estate costs have been prepared by an appraiser familiar with the area and are additive to the real estate costs included in the IJC report. The additional cost of widening the taking line for the wider approach channel to powerhouse No. 1 is added.

The western peninsula of Moose Island would be acquired for powerhouse No. 2, with a construction area on the southeastern end and another at the northwestern end. A strip along the southeast line of the approach channel will be

acquired, also areas for the abutments and approaches to the proposed replacement bridge. All of Carlow Island would be included in the taking; any remainder after the bridge construction would be developed for the use of visitors as described in chapter VI. All lands and damages in Canada remain the same as in the IJC report. Damages to waterfront property, caused by the tidal regime for the high and low pools, would appear to be unchanged from those developed in the IJC report.

3-23 Operation and maintenance

The operating and maintenance staff of a hydroelectric power installation is a large part of the annual costs. The estimate of operation and maintenance annual cost for the increments of size of the tidal powerhouses now under study is developed from the IJC report. The staff for locks, dams, and emptying and filling gates would be the same, with a cost increase in accordance with present wage rates. The staff for the varying sizes of powerhouse would increase with the number of units, as would the amount estimated for annual supplies. The staff would include a small executive section, an engineering section, an operating section to provide necessary around-the-clock service, and a maintenance section on an 8-hour-day basis plus emergency service.

3-24 Pump-turbine units

SUBJECTS FOR FUTURE STUDY

In searching for ways and means to improve the economics of the tidal power project, various ideas have been conceived. One of these, which is worthy of further study, is that of using pump turbines to increase the peak power generation during periods of neap tides. Using off-peak power, available from 10 p.m. to 6 a.m., the reversible units would pump water from the low pool to the high pool.

Then, during the daily period of peak demand, these same units would generate power as the water in the high pool would flow back through them into the low pool. By this means, the firm generating capability of Passamaquoddy could be realized, as the additional water and head could be used to extend the period of on-load operation, thus offering more flexibility in fitting tidal power to the load.

3-25 Dams, cofferdams, and gates

There are several features where study during the design phase of the project might result in a reduction of cost. The tidal dams and coffee dams present many problems of design and construction. General and detailed hydraulic model studies and extensive deep-water drilling would appear warranted. Further investigation may show that prefabrication of filling and emptying gates with a floated-in construction method would provide a saving.