THE WATER-WORKS AT BIG RAPIDS.
AN interesting description of the improvements made last year to the water-works at Big Rapids, Mich., is given by an exchange. Up to two years ago the city had used filtered river water, but desiring a purer supply, the citizens decided to obtain one from the earth. The works are now completed and said to be giving excellent satisfaction.
The engineers began work by sinking test drive wells about 100 feet deep until satisfied that they would hit the right location for flowing water. Then the reservoir was constructed as follows : A heavy circular frame of wrought-iron securely bolted and strengthened was placed on the ground over the spot where the reservoir was to be dug. This circle was thirty feet in diameter, and, as a matter of course, was hollow to allow the workmen to operate inside of it. Using this iron circle as a base to uphold the structure, a circular wall of solid masonry, brick and cement plastered, inside and out, was built upon it. The earth beneath was then excavated carefully, and the great tube was gradually sunk into the earth, successive additions of brick being supplied at the top as fast as the well was lowered Baulders were encountered freely in the well, but they were broken up and removed, and in the course of time the reservoir was finished to a depth of about thirty-five feet without accident or much expense, when the importance of the work is considered. Some water percolated into the well as it went down, but it was removed by pumps run by steam (the same power which operated the digging machinery), and the projectors of the well claim that a similar tube may be sunk in any place to whatever depth is desired, even though it should be in quicksand all the way. Water is the only thing that can interfere with the work, and that must be removed by pumps. Such a reservoir should be lowered to a solid rock foundation and then it will remain permanent for all time. When the thirty-foot reservoir was completed at Big Rapids, a four-inch wrought-iron pipe was lowered and driven by machinery into the ground a distance of 11S feet, till it encountered a good vein of flowing water. After that, other drive-wells were sunk in the bottom of the reservoir until at present there are ten of them within the circle, varying in depth from 118 to 164 feet. These pipes bring the water into the reservoir, and so great is the pressure below’ that nearly 1,000,000 gallons can be drawn every twenty-four hours without lowering the surface of the water more than three or four feet, while at times the water slops over the top of the reservoir and runs waste into the river. Every night the wastepipe is required to carry off the surplus. Another advantage which the Big Rapids water-works has, is that it is operated by water power at a total yearly cost of $900, while Jackson pays two and one-half times that sum for coal alone to run the pumping engine.