People's Gas Light and Coke Company of Chicago built a small factory In Sault Ste. Marie using the hydroelectric power transmitted from a cable across the St. Marys River from the Lake Superior Power Company's plant in Ontario.

    The company's engineer, William Smith Horry, had just developed a new carbide furnace that revolved, continuously producing calcium carbide. This company joined with the Acetylene Heat and Light Company of Niagara Falls to become the Union Carbide Corporation. The owners of this new company were interested in the power house as a location for their operation and, most importantly, they were not concerned with the Sault's geographic isolation. Union Carbide signed on in April of 1898, providing the capital to continue the project.

    Several design changes in the powerhouse took place. Union Carbide insisted their electric furnaces be placed not more than 30 feet away from the generators to reduce power loss, in order to provide the space for carbide furnaces, a second story would need to be added to the structure. It was also felt that a two story structure might have a more imposing and satisfactory appearance than just one floor, half submerged In a single story edifice.

    The Union Carbide contract also called for a financial reorganization of the hydroelectric project. The original Articles of Incorporation had been organized under Ontario law. Reorganization was prompted by the need to have the state of Michigan authorize the diversion of water from the St. Marys River. The formation of a subsidiary American corporation called the Michigan Lake Superior Power Company (MLSPC) took place in June, 1898, with Edward Douglas as its president and Francis Clergue as its vice president and general manager.

    An elaborate stock and bond sale was initiated that gave the company operating capital other terms of the contract called for taxation benefits from the city and county. In return MLSPC was to build the canal and powerhouse, producing at least 40,000 horsepower. They would also be required to construct bridge abutments for the permanent bridges which the city would later install.

    The plant was designed to power either Horry carbide furnaces and / or pulp grinders. A certain volume and speed of water was necessary in order to produce optimum hydroelectric generation. However, the water could not exert too excessive a force or it couldn't be contained properly. The design agreed upon consisted of a canal 200 feet wide and 23 feet deep and running in length two and one half miles from the intake to the powerhouse.

    At its end. The canal bent northward and crossed Portage Street. At this point, a widened forebay was constructed. In the canal, water traveled from six to seven feet per second. The bend would slow the water down in preparation for its entrance into the turbines. It was necessary for the water to flow at one to two feet per second when it reached the powerhouse. If it had traveled any faster, the vibrations and wear on the turbine chambers would be destructive. The walls of the forebay, much like the canal, were to be lined with unfinished logs. Since no erosion was expected on the bottom of the forebay, it was to be left unfinished.

    After the commitment was made to the carbide production, each penstock unit was set to produce 500 horsepower. In order to produce a maximum 40,000 horsepower, a minimum of 80 penstocks was necessary. A typical powerhouse at that time usually had from five to seven penstocks, but generated more electricity per penstock. While many power plants were using vertical shaft turbines, the horizontal style of the Sault plant provided an increase in power. No other hydroelectric plant in the world had that number of penstock units. To achieve the desired output, the powerhouse had to be a quarter of a mile long and today it still retains the honor of being the world's longest horizontal shaft turbine plant.

    The construction of the powerhouse foundation was very critical in powerhouse construction, this was often where the most mistakes were made. Test points on the shore of the St. Marys River indicated 15 feet of silt sitting on a foot or two of gravel which overlaid a bed of hard clay, 20 to 30 feet thick. Under the clay was bedrock. Eight test borings were made and because of uniformity of results, no additional tests were made. Von Schon erroneously determined that the entire area was the same. This error led to future structural problems which had to be corrected.

    The foundation was to be placed 16 1/2 feet below the surface of the St. Marys River, fully on clay. After coffer dams were built to keep the river water out, the silt and gravel over the clay was excavated and the site leveled. Next, more than 1,000 hardwood piles were driven 16 feet down and anchored across the top with concrete.

    Over this foundation, a system of tailraces, or enclosed tunnels, were built of concrete. The upstream walls were constructed of premolded concrete blocks. Penstock construction adopted by Von Schon contained several novel features. It was one of the earliest applications of skeletal steel construction for a hydraulic structure. Twelve-inch thick steel beams formed cells and were filled with poured concrete. For the dam at the forward end of the penstock, a semi-cylinder steel bulkhead was installed with 1/4" thick steel plates. This was a completely new design that was patented as a result of this construction. It eliminated a large amount of masonry and concrete that would have had to be substituted to hold back the water.

    The plan of construction in the rock sections involved channeling machines to block out sections of rock and drill crews with pneumatic drills to provide holes. Blasters then filled the holes with explosives and touched off the charges. Steam shovels or locomotive cranes then loaded rock into dump cars running along temporary tracks, and train engines hauled the cars to the dump area. In the earth sections of the canal, steam shovels did most of the excavation and loading onto dump cars.

Continued in Part 3

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Last modified: September 13, 2007