Potable Water and Fire Protection Water in one trench 3

[Hoagie]

Any problem laying both potable and fire protection water in the same trench?

FYI..The fire water is neither potable nor it is gray.

 

[cvg]

depends on who is approving your plans. raw water may not be allowed in the same trench.

 

[bimr]

10 feet of horizontal separation is required for water mains from drains, storm sewers, sanitary sewers, combined sewers, or sewer connections. This applies for piping installed with no special construction (drains, storm sewers, sanitary sewers, combined sewers, or sewer connections of standard construction).

Fire mains are not addressed in the standard specifications.

However, since both the fire main and potable water main are constucted of water main quality piping (this is considered special construction), you should have no problem installing both of these services in the same trench.

You should install the pipes at least wide enough apart such that you are able to operate a compacting machine between the pipes.

 

[Hoagie]

Right on. Thanks bimr.

 

[cvg]

note that separation is required between potable water and sewers, regardless of the type of pipe. not just for gravity lines and special construction makes no difference. for instance a sewer force main constructed of pressure pipe with mechanical joints (special construction) still cannot be installed in the same trench as a potable water. You may find that the approving agency regards raw water in nearly the same light as effluent, unless it is treated and disinfected. Check first with the approving agency before making this assumption.

 

[dicksewerrat]

Mark the asbuilts very well. So no one taps the fire line for a second building water supply

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[bimr]

It is not always possible to have the ideal 10' of horizontal separation. Most reviewing agencies follow the following guidelines:

1.9.1 SEPARATION OF WATER AND SANITARY AND/OR COMBINED SEWERS

A. Standards for separation of water mains and sanitary sewers lines.

B. PARALLEL INSTALLATIONS:

1) Preferred/Normal Condition – water lines shall be constructed at least 10 feet horizontally from a sewer or sewer manhole whenever possible. The distance shall be measured edge-to-edge.

2) Unusual Conditions – when local conditions prevent a horizontal separation of at least 10 feet, the water line may be laid closer to a sewer or sanitary sewer manhole provided that:

a. The water main shall be placed in a separate trench, with elevation of the bottom of the water line at least 18 inches above the top of the sewer; or

b. The water main shall be placed in the same trench as the sewer, and located to one side, on a bench of undisturbed earth, and the elevation of the bottom of the water main shall be at least 18 inches above the top of the sewer; or

c. Where this vertical separation cannot be obtained, the sewer shall be constructed of AWWA approved Ductile Iron Pipe pressure-tested in place to 50 psi without leakage prior to backfilling. The sewer manhole shall be of watertight construction and tested in place.

"Special construction" is constructing the sewer from water main type materials.

 

[rconner]

Beyond structural and joining requirements I think in general any potable and non-potable water sources and transmissions in close proximity require care on the part of a lot of parties (including designers, installers, later mechanics or whoever tapping etc.) Recent standards e.g. that you can read for yourself at

http://10statesstandards.com/waterstandards.html#8.8

(and for wastewater,just replace "water" in the URL) give quite a bit of guidance etc. with regard to many proximity and other issues. Notice that of all of the standards rigamerole having to do with with parallel or various "crossings" (consisting of intersecting pipelines or pipelines going across other sources of potential contamination or sensitive structures/environments/features etc.) is also immediately followed by passages in these standards about preventing "cross-connection" etc.
Maybe particularly if there is any chance that the potable water line in the area may have to be dug up and tapped for connection in the future it would be a good idea when the parllel installation or crossing is made to also to well-mark the lines (all kinds of pipe can of course now be durably marked for the services in such locations with very close parallel or even colored/labeled/marking tapes spirally wound around the pipes, special colored and/or labeled polyethylene wraps, or other means, and of course taps could even conceivably be installed to draw off and test samples of withdrawn water from any suspect pipe/line before someone drinks from a new service (as appears to be at least hinted in some crossing areas of standards). Where potable water and other pipes etc. must be installed in close proximity, there may also be some value to very strong/robust (impact/gouge/damage-resistant etc.) pipe materials in general, as "stuff happens" and maybe particularly in such congested areas.

 

[cvg]

note that these 10-state standards apply only to 10 states, not the other 40. Standards are different around the country. For example see the following standard and attached special protection requirement:

see section R18-5-502

http://www.azdeq.gov/environ/water/permits/download/subd-rule.pdf