Rural water is coming-need advice!

[SilverCity4]

Rural water is coming to our fire district in the next two years, and we're pretty excited. We do have some questions, and so I humbly ask for everyone's opinion.

The roads around these parts are generally built on mile section lines, so it's a four-mile drive to get around the block. The water district plans to run 6 to 12 inch mains down the roads. They also are going to install hydrants every quarter mile. They said that they will install as many more hydrants as the FD will buy (or homeowners, I assume).

Is there any criteria for hydrant spacing? At a quarter mile apart, the farthest distance from a hydrant along the road would be 660 feet, but we still need to lay a line up the driveway, and those get pretty long 'round here. And the farther you go, the more friction loss you get, so the bigger supply line you need, right? What other concerns are there?

We're not very familiar with this stuff, so lay it on me, folks. Pretend we know nothing.

[ 08-07-2001: Message edited by: Silver City 4 ]

[DaronG]

Here are some variables you may want to look at. What kind of flow pressure will you have on these hydrants. It sounds as if it will be fairly decent. Assuming this is a gravity powered system (water coming off of towers with no pumps to assist before the hydrants) this will depend on the piping and the elevation difference between the water level and the hydrant (the higher the water level above the hydrant the better). It is recommended that you leave 20#'s residual pressure on the hydrant even at full flow and this is what most rating bureas consider as available water at the hydrant. Another thing to consider is do you plan on using a relay on any lays except those where the fire is very close to the hydrant. I would recommend this myself but if not possible you will want to consider 5" or bigger supply line. A lot of departments do this even with a relay to cut down on friction loss and increase available water. Are you going to need flows in excess of 500 Gpm's? If not then you may be able to get by with a relay truck and a hoselay where you can drop one or two 3" lines on the ground between the attack truck and the relay truck which should be positioned as close to the hydrant as possible. If your hydrants are going to be spaced at least every 660' then the longest relay you should have is 330' plus lets say 170' up a driveway leaving a 500' relay. Assuming your hydrants will be capable of supplying a relay truck 500 Gpm's after it hooks up its supply lines you should be able to supply 500 Gpm's over a 500' relay with a pump discharge pressure of somewhere close 150 PSI with one 3" line on the ground. There are other ways to do the same thing but this will give you something to start with. If you figure on putting two 3" lines on the ground you can double this flow at the same discharge pressure. With a single 2 1/2" line I personally wouldn't want to try this flow at this distance unless I had another relay truck inline about half way because of the high pressure it would take. Two 2 1/2" should be feasible at that distance. Keep in mind though these figures are only estimates and may vary depending on your pump, hose, and elevation changes. I usually allow +/-5% for unforeseen circumstances. If you give me an exact layout with flows and elevation changes I can give you some better estimates. Just let me know and I will try to help anyway I can.

[Dalmatian90]

Quick random thoughts...

1. ISO generic credit is for the driveway to be within 1000' of the hydrant, so spacing is OK.

2. Figure maximum of 1000' to driveway, and 2500' (half-mile) up the driveway would be 3500' of 5". Probably could get away with a bit less -- depends just how long your driveways are.

The hydrants are still a few years off, so you have time to start buying a little bit of hose each year to build up your compliment.

3. 6" to 12" sounds a bit small on the size, but if it's being built as a grid probably adequate. If it's being built more or less as a trunk with a bunch of dead-end 6" branches I'd be worried -- time to talk fire flow with their engineers.

4. What is the fire flows currently for the area, and what is the type of development envisioned? It would be ashame to build a water system that can't meet today's needs; or that couldn't meet 3500gpm if commercial/industrial development is planned.

You dig just as big of a trench for 16" as 12", so look at the current and planned fireflows, and make sure the district puts in pipes big enough. Even if they can't supply the flow today from the wells/reservoirs, if the pipes in the ground you can add supply later easily. Kinda tough to dig 'em all back up in the future.

So if you need the same amount of manpower, machinery, and time to put in 16" as 12", see if you can justify the small extra cost of the bigger pipe today.

ISO Rating stuff can be found at www.isoslayer.com (interesting reading!) -- follow the Your Next Rating link.

The decisions you make today on the water works, your grandchildren will be living with when their Chief and Mayor -- make good choices today!

[RJE]

Howdy Neighbor,

Good points from Dal about main sizes. Where I grew up we had problems w/4 and 6 in. mains. They'd only flow about 400gpm w/o dropping below 20psi, so they were pretty weak for FF.

On the other hand, strategies for dealing with it (w/ or w/o bigger mains):

Do you have Tankers now?

Here's what we did (suburban/rural dept - be about like Sand Springs for comparison). We had 3 stations, 3 pumpers and 2 reserves, 1 Quint and 1 tanker. Response for a structure in a rural area would be 3 pumpers and the tanker, unless we were sure access for the quint wouldn't be a problem, or we knew we'd have a large structure (barn or whatever) where we'd need it. These areas were extensively preplanned. You don't mention truck ops, so I'll assume w/o the quint.

Pumpers all carried 1200' of 5". First in lays up the driveway - unless a preplan showed the driveway to be more than 1200'. The idea was to get the 'attack' pumper properly spotted close to the structure. If the hydrant was right on the end of the driveway, they might catch it, but only if they knew they could reach the house.

Tanker was 2nd due on most rural fires (and came out of the house with the best daytime staffing) so it's job was to set up the "water supply". What this consisted of depended on the location. No water, it would drop tanks and tools for the next in pumper to start drafting, dump it's load, and start a relay. But if we had a 'questionable' water supply (hydrants, but not good ones), they'd hook up to the driveway lay and 'nurse' the attack pumper. The tanker had limited hose, so now he's stuck, but the next due will always be another pumper, who'll "bring a line from the hydrant". Then they'd circle back and 'boost' it, or let the next in take that duty (depending on how many trucks actually made it out of the house).

There were only a couple of places (where we had water at all) where 2 pumpers w/1200' each couldn't get all the way in, and generally we knew where those were.

Now where it really gets tricky is brush/grass fires - that might be even further off the road. But that's another story (and 4 1-ton brush trucks really come in handy).

[SilverCity4]

Every time I've had a chance to answer a question, another post has popped up. If they didn't expect me to WORK at my job…

Okay, it will be a gravity-fed system, though I don't know the capacity or elevation of the tank. And it's going to be a grid, but I'm not sure what size feeder lines. And after a quick call to the Assistant Chief, now I'm unsure about the distance between hydrants. Might be longer.

Don't know the pressures that the hydrants will put out, either.

As far as flows are concerned, the largest building in our district is a church at probably 6000 square feet. Next are probably barns. Most of what is out here is pasture and woods. The only commercial business is a gas station. I don't think that we'll need more than 500 gpm right now, or in the near future.

And no true "trucks"-one pumper, one tanker, three brush trucks. Probably adding a second station within 24-36 months, so we'll probably add another brush truck and pumper.

Development? Hard to say. I anticipate several properties being broken up and sold, but I don't think there are any plans for major housing developments, but that could change real fast. And commercial/industrial? Doubt it. Definitely nothing in the works. Of course, getting utilities to a location is a good way to increase development.

As far as grass/brush fires go…if there's a 4 inch line with a hydrant every mile it's a whole lot better than what we have now, which is a 10000 gallon tank at the station with a 100 gpm electric pump or driving out of the district to the nearest hydrant.

[SilverCity4]

...sorry, double posted....
...Bad dog!! No!!...

[ 08-07-2001: Message edited by: Silver City 4 ]

[Dalmatian90]

As far as flows are concerned, the largest building in our district is a church at probably 6000 square feet. Next are probably barns. Most of what is out here is pasture and woods. The only commercial business is a gas station. I don't think that we'll need more than 500 gpm right now, or in the near future.

Think again

ISO Insurance ratings already are looking for that church to have a fire flow somewhere in the 1750gpm range (assuming 1 story, woodframe, no exposures).

'taint hard with commercial buildings of modest size to get to 3500gpm flows. The folks designing the water system are engineers -- figure out fire flows for current buildings like the church and barn to show the present needs.

I don't care really what the hydrant spacing is -- a few hydrants 1/2 mile apart on 12" or 16" mains will deliver a lot more water than a bunch of hydrants 500' apart on 6" mains.

Another interesting site: http://firehydrant.org/info/

[SilverCity4]

ISO Insurance ratings already are looking for that church to have a fire flow somewhere in the 1750gpm range (assuming 1 story, woodframe, no exposures).

Yikes!

We just made Class 9 in 2000, and are hoping rural water will take us to Class 8. Are the flows going to matter (besides the 250 gpm for two hours for Class 8) before Class 7?

If the church wasn't DIRECTLY ACROSS THE STREET from the fire station, maybe we could distract the raterS...

[Dalmatian90]

My guess is the hydrant system should boost you right into Class 6, maybe 5 within 1000' of hydrants. Rural (non-hydrant) area won't see a change.

HOWEVER, if you go for improving your rural ratings, it sure helps your tanker shuttles if you have hydrants putting out 1500gpm -- since they'll fill tankers 3 times faster than a 500gpm hydrant. Can't do much about travel times, so you need to minimize fill/dump times.

You know, this is a great opportunity to develop some long range plans for the water system and fire department together -- what you'll want (eventually) from both. There is also something called Divergence in the ISO ratings -- Got a great FD and poor water system, or vice versa you get penalized. Gotta keep 'em both up to snuff.

[RJE]

Dal:
Great points about joint development. My old dept. did that, eventually.

What actually happened was we were the "town" VFD, but there was a lot of development of suburban housing outside the city limits. That's when we ran into all the hydrants on 4" mains.

Later, we became a fire protection district (tax-base funded and w/responsibility for the out of city area) about the same time the "water company" became part of the "Rural Water District" system.

After that, we looked at the size of developments, the size of the buildings in the developments (some had rather large community centers and such), and other factors.

Now, (my dad's still on that dept.) the water district managers and the FPD Fire Engineer always work together on major planning functions.

But even after 30 years - half the district still has NO water.

[EastKyFF]

As far as your ISO potential goes, a few things I've learned:

1. You can probably get a 7 with the hydrants but you'll probably have to have a 2nd rated pumper to get any lower. We have 2 pumpers and just got to a 5 thanks to hydrants.

2. Spacing of hydrants is not as critical as it first sounds IF you have adequate laying-in capability. As long as you can get enough LDH on the ground to reach every structure, they can stretch that 1000-foot thing.

3. Invest in quarter-turn couplings for your LDH. It is the only way to operate.

4. You might do better to expand your existing station rather than add a second one IF it will not bring any more properties into the 5-mile radius. The reason is the value of that 2nd rated pumper in your ISO survey is higher (I think) if it's out of the main station than if it's a substation.

Have fun!

[ttjjss]

i would say there needs to be as much 12 inch as possible, and if its only running off of one tower it needs to be looped back to itself. run 12 inch outas the main feeder and if necesary run smaller out in one mile square loops back to the 12 inch, always keep the lines looped, nothing kills flows more than dead end mains, be sure and get the good hydrants not the cleanouts with just dual 2 1/2" outlets, make sure they are all the same as to the outlet sizes.
Tyler

[SilverCity4]

We just finished adding on to our station.

The second station is dependant on a merger with an ajoining FD...long story, but they have a small community with an FD that's all but gone, so we offered to combine forces. The second station will go in that community (plus, there will be areas outside of 5 road miles of Station One when the merger goes through).

Seems like the general idea is that long hose lays isn't something we need to get all worked up about? I'd like it if every house had a hydrant right in front, but that's not going to happen. We can buy hose cheaper than paying for a bunch of hydrants.

[RJE]

Check your hosebed size vs. size of hose. If you're going to have one pumper in each station - then give each as much LDH as will fit (within reason, and that you can afford).

There's generally not a problem with long lays of LDH.

Just make sure you run both pumpers to every rural structure fire.

[david2]

go with the 5 inch supply lines we took the longest driveway we had and add 1,000 ft to that seems to work pretty good , as for the iso read larry stevens book its great he knows what he is talking about.