3.1 Transmission System

Transmission System is the system of piping, fittings and valves usually buried below the frost line and under the street. Most cities and towns have a local water commission or local water authority who takes responsibility for delivering potable water under pressure to the residences and other businesses plus municipal and commercial facilities in their jurisdiction. The transmission system of piping ensures that all parts are bottle tight and does not allow any contaminants to enter the system. The piping must be rated to carry potable water. The installation and maintenance of the piping under the street is not covered by our Plumbing code as it is off of the property that our code does cover. This system of mains and branches are covered by engineering associations and water boards administered by municipal, provincial and federal governments.

Many large cities have separate potable water mains and separate fire mains while here in Nova Scotia our cities and towns share one set on mains for water and fire service. Therefore the water that comes from the fire hydrant on your street is the same that comes out of your kitchen faucet.

A corporation cock will be tapped into the side of the main and from there the water service line will run to the curb cock. The curb cock can be on the side walk, edge of property, start of drive way or at the property line. The curb cock will have a valve box or curb box attached over the valve that is used to access the valve to turn it on or off. From there the service line runs in to the residence coming in under the footings or through the basement wall. The water service is run in a gravel trench well below the frost line.

Once in the house/building a meter valve is installed on the line usually very close to the wall. Most water purveyors will state how much pipe they will allow before the meter.
Usually 3 to 4 feet is the maximum.

Corporation Stop

The valve installed on the water main by the municipality. This is usually done under pressure using a “Live Tapping” device.

Gooseneck

An arched bend in the water service is typically installed to prevent strain on the corporation stop from soil movement and pipe expansion.

Curb Stop

A valve installed by the municipality to service the premises. The curb stop is a quarter turn ball valve that can be fitted with a valve key to turn on/off the water and is protected by a small diameter valve box that extends to height of the finished grade.

Main Shut Off

As soon as the water service enters the building an isolation valve must be installed.

The transmission lines must be securely fastened and anchored in order to keep it in its place. Many different methods are used to accomplish this including the more common thrust blocks. The following pages of this section have several examples of thrust blocks and the methods and ideas of securing the piping.

Below are some common thrust blocks. The following pages of this section have several examples of thrust blocks and the methods and ideas of securing the piping.

The picture below shows the water main with the corporation cock (stop) connected above the horizontal center line of the water main. This is a good piping practice to reduce or eliminate dirt and silt from entering the building during periods of high-water usage. Note the gooseneck acting as an expansion joint leaving the water main. This piping arrangement is to allow for pipe movement during shifting soil conditions such as seasonal temperature changes. Next you can see the curb cock (stop) and the valve box or curb box (valve extension) sitting over the valve. The curb box allows the water to be turned off from outside the building if the meter valve is broken or not working properly. From there it runs into the building to the water meter, main shut off valve and pressure reducing valve if required.

The flange below (uni-flange) can be installed on the ductile iron water main and a valve or any flanged fitting of the same size and can be installed just about anywhere.

Once the pipe is cut to length the flange is two holed and then the bolts are tightened until they snap off. The bolts are specially made to snap off at a specified torque so that no undue stress is applied to the pipe, just enough to keep it secured. They could connect to the hydrant main valves shown below.

Usually large piping in underground water mains are restrained with thrust rods which really are just plated threaded rods bolted between fittings, pipe and valves. Their purpose is to keep the piping together when we have some settling of the pipe and water hammer conditions.

Valve box keys are specially designed to fit down inside of the curb box or valve box to turn off or on the water supply to the building. Some municipalties will allow plumbers to turn the water off and on when making repairs inside of the building, such as replacing the meter valve. However most municipalities do not allow you as a plumber to touch the valve. Usually if this the case the water commission will come and shut down the water (curb cock) for you as a free service. It is all figured into the cost of the water to the building as a service. Most times the water purveyor will come out the next day if called ahead of time, don’t forget they are working on a schedule too. In the case of an emergency they might be there in a matter of minutes or as quick as they possibly can.

Many plumbers have made up valve handles and take the chance of turning the water off themselves. This may be fine if you have permission to do so but if not and you break the curb cock your company might pay the cost of digging up the valve box and changing the broken valve. So if it takes a planned shutdown and a phone call why would you take the chance. Imagine the cost of digging up the valve and maybe the pipe and then possibly add the cost of repaving. Usually the water purveyor would have the valve or piping that you broke repaired by them or have the work completed by another contractor and then bill that back to your company. Why would the water purveyor have you fix something that you weren’t authorized to touch in the first place. Its like the old “call before you dig” warning when working around buried water service, gas lines, electrical service lines etc. That phone call is a whole bunch cheaper than repairs later and more important is could save you or someone else s life! Are you convinced (make the call).

Image Credits

1. Plumbing Help. (n.d.). Water service pipe. https://plumbinghelp.com/water-service-pipe/
2. Ford meter. (n.d.). https://www.fordmeterbox.com/products/catalog/a?line=34
3. Evan supply. (n.d.). https://www.evansupply.com/products/curb-stops
4. Kentucky department of environmental protection. (2012, July 12). Typical thrust block detail for PVC pipe & ring pipe. https://kyocp.wordpress.com/2012/07/31/thrust-blocks/
5. Bahrain Pipes. (n.d.). Direction change, elbow. http://bahrainpipe.com/En/22/Details
6. Traxco. (n.d.). Gate valve thrust block. http://www.traxco.com/thrust-blocking
7. Green Mountain Sprinkler, Inc. (n.d.). Underground water main with thrust block. http://www.greenmtnsprinkler.com/photo_gallery.html
8. Mueller Co. (n.d.). H-10003N. https://www.muellercompany.com/water-works/service-brass/corporation-valves/ground-key/h-10003n
9. Mueller Co. (n.d.). H-15217N. https://www.muellercompany.com/en-ca/water-works/service-brass/curb- valves- boxes/solid-tee-head/
10. Plumbing Help. (n.d.). Water service pipe. https://plumbinghelp.com/water-service-pipe/
11. Wexford Piping & Fittings Ltd. (n.d.). Uni-flange for ductile iron. http://www.wexfordpipingandfittings.ie/ductile_iron_fittings.htm
12. EBAA Iron. (n.d.). 1600 split serrated restraint harness. https://ebaa.com/products/pvc
13. The General Engineering Company. (n.d.). Valve keys. http://www.genecosealtite.com/product_page/geneco-valve-stem-extensions- and- valve-keys/