One Town, Two Water Systems, One Building

[RemoteControlFF]

I have a project in a town with two separate water systems, each fed off of its own water tower, which are not connected. The water running into the building cannot support the system demand with outside hose, so the owner wants to bring a line from the other water system (which dead ends about 350' away) closer to the building and stick a hydrant on it. This would have the FD on one water system and the building on the another.

This feels like cheating, am I wrong?

 

[Cidona]

I would think if the AHJ/s includeing water departments are ok with I'd feel fine about it. I've had systems with storage tanks for the water supply for the sprinklers and the FDC does not connect to the main suppling hydrants. Even coming off a city main, you'd usually have a FDC upstream of a backflow/alram check which prevents water from the FDC going into the hydrant main. Only in a few cases have I had FDCs as a feed for the hydrant main. So long as each supply would be concidered a reliable source. You would have to make absolute sure that they are in fact not connected from the same water tower.

 

[RemoteControlFF]

Thanks Cidona.

I was thinking that it would be OK - and as they are both city supplies, I wouldn't think there would be any cross-contamination concerns (it won't be possible to cross-connect them, but just the same). We know for a fact that they are 100% segregated, as we originally thought the building was on the other system!

Now I just have to pound it into the building owner's head that the hydrant has to be accessible and within 150'... love Mondays!

 

[SprinklerDesigner2]

I certainly don't see a problem and fact is it offers a superior level of protection.

Should one city main fail you have a backup for either sprinkler or hose streams. Couldn't get much better than this in my mind.

Sprinkled a bakery once where city water was 50 static, 25 residual @ 300 gpm. Certainly not enough for sprinkler but perfectly adequate for hose streams.

For sprinkler (density .20/1,500) we used a 250 gpm vertical turbine pump taking water from a small 25,000 gallon cistern partially located under the floor at the end of the building. 3,333 cubic feet of cistern we made it 10' deep, 12' wide and 30' long with just a corner and sump under the floor itself. One of the neatest jobs I've done.

 

[TravisMack]

SD2,

That water might have been OK for an outside hose allowance per NFPA 13, but would be no where near adequate for site water flow as req'd by the IFC, which is typically around 1500 gpm @ 20 psi.

I always find it interesting when working in an area where the water supply can not supply the hydrants per IFC tables.

Travis Mack
MFP Design, LLC

 

[RemoteControlFF]

Travis,

Do many communities / states adopt the IFC tables? I don't think more than 15% of the locations I've seen flow information on in my state could meet those requirements... the building this thread is about would only have about 45% of the required flow without the additional hydrant / water main tie-in.

 

[TravisMack]

I have done work in Louisiana and I don't think many areas could meet those. Other than that, most of the areas I do work in the southwest can meet the IFC requirements. Some cities even want the requirements put on the fire sprinkler shop drawings.

Travis Mack
MFP Design, LLC

 

[SprinklerDesigner2]

Travis,

It was many years ago before the IFC and it was one of those quaint places where the guy who owned the bakery owned the town and nobody would say no.

Fire flows... haven't had to deal with those except in Florida.