RECOGNIZE LEAD WATER MAIN
Identifying the presence of a lead water main is the first step. Lead is gray in color, with no shine (dull) and sinuous (the lead water main presents curvatures). Here are some examples:
DIFFERENTIATE A LEAD WATER MAIN FROM A COPPER OR GALVANIZED STEEL WATER MAIN:
|Presence of bulge-type joint||yes|
|Easy to bend||yes||yes|
|It can be scoured with finger nail||yes|
|Copper-colored when scraped with a metal object||yes|
|Presence of rust||yes|
|Attracts a magnet||yes|
|Presence of verdigris (greenish oxidation color on copper)||yes|
|Resonates when percuted||yes||yes|
Copper water main:
Note the copper color, the presence of verdigris and the rectilinear shape.
Galvanized steel water main:
Note the dull gray color and the straight shape.
REPLACEMENT TECHNIQUES FOR A WATER MAIN:
Replacing a water main can be done by either of the following methods: conventional excavation and water line pulling.
During a conventional excavation, a trench is excavated from the starting point to the point of arrival of the water line. In other terms, this trench is dug from the foundation of the building (at the location of the main shut-off valve in the basement) to the curb stop valve. This method involves dismantling or demolishing what is between the starting point and the point of arrival. Balcony, sidewalk, asphalt, paving-stone, tree and landscaping are affected and must be rebuilt following the work.
During a water line pulling, a continuous trench does not have to be dug: only two access holes are dug. The first one is 12 “(width) x 24” (length) x 12 “(depth) and is dug inside the building at the location of the main shut-off valve. The second, a size of 5 ft (width) x 5 ft (length) x 6 ft (depth), is dug at the curb stop valve. Then both ends of the lead water main are cut and opened. A steel cable is passed inside the old lead line and the new copper line so as to create a “train” of pipes. This cable is connected to a hydraulic water line pulling device: the cable is pulled and brings with it the two lines of water “train” or assembly. The old lead water main is removed and the new copper water main follows and replaces it.
The advantage of a water main replacement by water-line pulling is of course the speed of execution and the reduction of the damage to landscaping. This reduces costs for the work itself and for the restoration of the premise after the work. Although it is a great technique, water line pulling does not always work: the inside diameter of the lead pipe is too restricted, the underground curves are too pronounced, there are large rocks adjacent to the pipe, the ground is too hard, the cable is breaks, the pipes are disassembled. In the event of a water line pulling failure, the conventional excavation takes over finishes the work.
MONTREAL AND SOUTH SHORE