YARMOUTH WATER SUPPLY
Paper read at the twenty-sixth annual convention of the American Water Works association.
That a better understanding may be obtained, I will give you a short description of the gatehouse, intake pipes and supply main to pumping station. The gatehouse is 17 by 12 ft., divided in the centre with a 12-in. brick wall, making two inlet chambers provided with valves and screens. Three 12-in. pipes enter these chambers from the lake. When the lake is at its highest level, there are seven feet of water over the inlet pipes. The average fall of the lake is twelve inches. In 1891 the old supply main for a distance of 2,000 feet from the gatehouse was taken out, the trench was deepened and replaced with two la-in. mains laid on a true hydraulic grade, and connected to the old main. This work was very expensive, owing to the soapy clay or quicksand formation, depth of cutting and heavy crib work. The average depth of the trench was ten feet, For the last fifteen years the single 12-in. supply main to the town has been gradu 8lly fUhin~ with tubercular formations. These incrustations have so reduced the head or sup ply that, after three hours running of the pumps, the gauge drops frcui a so-lb. pressure to a 3-In. vacuum. The consequence was that we pumped a mixture of air and water, which also caused the pumps to pound and rattle. In September this year work was commenced at the point where the duplicate main laid in 1891 connected with the old main. Before connecting the new pipe, we found that both the pipes laid in 1891 were heavily coated with tubercles. Not having any device for cleansing pipes, I dressed a piece of wood hexagon in shape, three feet in length, with a disk of wood one inch smaller than the nine, holted on the end. On the front, or cutting end, I fitted short steel scrapers placed diagonally with the pipe, filling between the scrapers and disk with stiff steel brushes. The scrapers cut the tubercles, and the brushes cleaned the pipe. In the centre of the stick a l-in. hole was bored; through this hole a piece of strong rope was passed, with thimhles spliced at each end. It was not possible with the low head to force the scraper through the pices by water pressure. To overcome this difficulty, we floated a small line through the pine with a block of wood attached, then drew a heavy line made fast to scraper. By frequent ramming with the water and eight men hauling on the rope, we managed to get it through. Before making the second cut, we spread the cutters and brushes, and succeeded in giving the pipe, a thorough cleaning. You will understand that this contrivance was built cheanlv, with room for improvement. The cost of the scraper was $5; of the rope, $20. The time of cleaning 2.000 feet was four hours. From the end of the pipe now laid and cleaned we extended the new main another 1.000 feet, ns shown in the illustration. We could not disturb the old main until after the new pipe was connected, on account of depriving the town of water. We cut. made connection and turned on the water three hours from the time of shutting off. After the water was turned on in the new pipe, we disconnected the old main, removed, cleaned and relaid. The old main was laid without any regard to grade, and was verv irregular. In many places the pipe was laid over hills, that could easily have been avoided. This line of pipe is nine miles in length; it has been in constant service for twenty-two vears. and was so badlv coated with tubercles that I concluded it would be easier and cost less to take out. correct the grade line and clean by hand. 1or this purpose I made a scraper of different design from the one used with the rope. We dis connected and lifted 900 feet out of the trench in ten hours, with six men, four on the derrick and two in the trench. The method adopted to break the joints was: First, lift the end of the pipe with the derrick, then block under the bell end. By lifting and dropping suddenly, the lead worked out without any trouble. This make of pipe is turned and bored; it has no groove or recess for holding the lead. No gaskets are required, it is quickly laid, and, when properly caulked, will stand a 200-lb. pressure. Every length of pipe is rammed tight and solid. For ramming we use a piece of timber 20 ft. long and 6-in. sq. We cleaned and relaid the 900 feet of pipe in two days, with ten men. As a result of this short extension and cleaning, the pumps got a better supply of water, run smoothly with no vacuum. We will probably make another extension next year.