Water Distribution

[mflam]

I work for an old New England town. Lots of ledge, elevation change and dense overgrowth.
We want to eliminate some dead ends in the water distribution system. If I have two 8-inch dead ends about 400 feet apart, tough field conditions. There is plenty of fire flow at both ends.
Instead of 8-inch CLDI, I'm considering connecting the two dead ends with 4-inch HDPE.
Comments, pro and con, please.

 

[cvg]

is this just to circulate water and reduce flushing? 4" will probably work for that. However, you will still need to trench through the ledge, trees and steep terrain - so your main savings is in reduced number of fittings and thrust restraints.

 

[coloeng]

Or are you looking at directional drilling for the installation and that is why you are looking at hdpe? As cvg said, 4-inch should be adequate for circulating the water if you are not relying on it to increase fire flows.

 

[RWF7437]

The main purpose of "looping" water mains is not to provide circulation, although that is one benefit. Rather, lines are looped or gridded to increase reliability. In your case, each dead end 8-inch line might be expected to provide a fire flow of between 500 gpm to 1000 gpm. If the two are looped with an 8-inch the flow could be nearly doubled. But, more important, even if one line was out of service for some reason you would still be able to provide close to the 500-1000 gpm fire flow.

My suggestion would be to connect the two lines with an 8-inch, materials could be DI, PVC, maybe PE or any other allowed in your system.

good luck