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View Full Version : Cost of building a bridge across a creek. vs. pipe and covering it



LMH
Sep. 24, 2009, 02:07 PM
Since my pipe/culvert washed out I am considering doing a bridge instead.

Concrete, metal, wood or just replacing the pipe system. We currently have a pipe with big rock, cover the pipe in dirt/crusher run.

Has anyone put in a bridge (strong enough for a truck/trailer to cross) across a creek?

How long/wide was yours and what was the approximate cost?

The bridge certainly has more eye appeal and would allow water to freely flow-but I fear it would be insanely expensive.

JSwan
Sep. 24, 2009, 02:19 PM
LMH -

I don't know the answer to your question. But I was thinking that after a natural disaster there are often grants, loans and other assistance available from entities such as ARC, FEMA, and perhaps the state.

I'm out of the loop these days (retired) so am not up to speed on what programs might be out there.

Your insurer may be able to provide some referrals (I don't want to pry but I'm assuming you did not have flood insurance so cannot go that route).

I'd also contact the extension, soil and water conservation district, and the USDA or at least keep your eyes peeled for any assistance that might be available. You never know.

Where I live, there is a tremendous amount of floodplain and we do flood a lot. Often you can take measures to mitigate impact, such as installing larger culverts and also installing floodgates. Floodgates (for your purposes) would look just like fencing and act like fencing. But when water rises, the fence rotates enough to allow floodwater to pass, then rotates back down as waters recede.

With the larger culverts, more water could pass at a greater rate, reducing velocity and backup.

If a bridge proves too costly for you, the larger culverts and floodgates might be a less expensive option.

Anyway - hope that helps or gives you some ideas. Good luck and keep your chin up.

LMH
Sep. 24, 2009, 02:26 PM
Thanks JSwan-no flood insurance, you are correct.

There is supposed to be some relief from the government-but I have not found the details or who is included.

We have one fence that crosses the creek in a different location and do plan on installing flood gates at that crossing.

I have a funny feeling it will be additional or larger pipe like it was-it would just be SO quaint to have a little bridge on my farm!:D

Thank you for the relief suggestions.

Things are actually going very well. My gate will be repaired today (all new electronics-ugh) and the county is going to repair the BIG culvert that runs from my field on the road on Wednesday.

The bridge/culvert work on my farm will start as soon as I decide which way to go-if simply replacing what I had, then it will be finished next week.

Arena Sand and gravel for roads will be the end of next week IF the quarry for the sand is above water by then.:eek:

And finally half the fencing is complete-the rest will come after the above repairs!

Today I was actually able to ride in my sparsely sanded arena!

SevenDogs
Sep. 24, 2009, 04:43 PM
Pipe Culvert almost always (if not absolutely always) cheaper than a bridge. I think the price difference (particulary a structural bridge to support vehicles) will be prohibitive. Sorry, not what you wanted to hear!

Bluey
Sep. 24, 2009, 04:51 PM
If your span is too wide for one small culvert and not deep enough for a bigger one, you can use two or three smaller culvers there.

Ask your local Farm Service Agency, they sometimes have or their Soil Conservation Office has money for water projects and culverts or bridges may be approved thru them.
They can cost share up to 75%, so it makes sense to try to see what they tell you.:yes:

Hilary
Sep. 24, 2009, 06:46 PM
I don't know for sure, but since we re-built some washed out culverts for about $300-$500 I am guessing that a bridge strong enough to let a truck/trailer or tractor cross it would be a lot more expensive, nevermind the engineering needed to make sure it was strong enough.

Our rebuilds are 20' long and we used 18" culvert pipe. One used concrete, the other just rocks. We have sufficent rocks in NH just lying around that we didn't need to buy them.

ReSomething
Sep. 25, 2009, 01:52 AM
Bridges cost a mint, culverts are lots cheaper.

When our area flooded in '97 FEMA set up shop in a building downtown along with the SBA and you could take out a low interest loan to make repairs. They would only loan to the extent that you had what had been there before, no improvements, but it paid for a third of the cost of rebuilding our creek bank and installing rock to keep further erosion at bay. So they would loan you enough to put back the culverts, possibly bigger, but not enough for a bridge. We had to go in as a business with all our tax papers, P and L etc. The section that was eroded was at our home but happened to be our dry storage lot for the business.
Hope that you are able to hang in there and get your place back in order as easily as possible.

nightsong
Sep. 25, 2009, 03:32 AM
Bridges don't back up like culverts do, so your likelihood of making it through floods should be a whole lot better.

LMH
Sep. 25, 2009, 07:01 AM
Bridges don't back up like culverts do, so your likelihood of making it through floods should be a whole lot better.


THAT is the dilemma. The cost on the front end vs. long term.

Then again, this was the 100 year flood-so they say.

DiablosHalo
Sep. 25, 2009, 07:12 AM
Call your local conservation district and the USDA-NRCS office (in same building in each county but one is local level, other is federal). There is a cost share program for "stream crossings" through the NRCS that will pay a good chunk of the cost IF it is for livestock crossing OR farm equipment crossing (so tell them the tractor/mower/seeder/fertilizer trucks, etc must pass over). Good luck!
Main site should be www.nrcs.usda.gov then click on office locator...

Just found the info for your county...

CALHOUN SERVICE CENTER
717 S WALL ST STE 1
CALHOUN, GA 30701-2649

(706) 629-2582
(706) 629-1128 fax

Farm Service Agency
Natural Resources Conservation Service


You will have to sign up with the Farm Service Agency as a producer. Prove that you have a farm and farm income (usually schedule F will be enough). NRCS also has programs for fencing, drainage, tree plantings, roof gutters, pasture/hay seeding, etc.

JSwan
Sep. 25, 2009, 07:29 AM
Yikes - I hope they don't think the term means it only floods once every 100 years.

That's a common misconception.

Here is the definition of the 100 year flood - from the FEMA website.

The term "100-year flood" is misleading. It is not the flood that will occur once every 100 years. Rather, it is the flood elevation that has a 1- percent chance of being equaled or exceeded each year. Thus, the 100-year flood could occur more than once in a relatively short period of time. The 100-year flood, which is the standard used by most Federal and state agencies, is used by the NFIP as the standard for floodplain management and to determine the need for flood insurance. A structure located within a special flood hazard area shown on an NFIP map has a 26 percent chance of suffering flood damage during the term of a 30 year mortgage.


Structures located in Zone A (100 year floodplain) require flood insurance.

Here is an explanation of what all the designations mean. Anyone who owns a home, farm or land is going to find this very useful.

http://msc.fema.gov/webapp/wcs/stores/servlet/info?storeId=10001&catalogId=10001&langId=-1&content=floodZones&title=FEMA%20Flood%20Zone%20Designations


FEMA is currently updating the flood maps in the US, and using modern methods to determine BSE's (Base Flood Elevation). You can imagine it's a huge project and will take some time.

Your county GIS maps (which may be on-line) should show flood plain delineations. You can also obtain a flood map from FEMA or other agencies.

Here is a link to the FEMA site - you can type in your address for a map.

http://msc.fema.gov/webapp/wcs/stores/servlet/FemaWelcomeView?storeId=10001&catalogId=10001&langId=-1


What you can do with the GIS maps is pretty neat. The FEMA map is only going to delineate the floodplain/zones. But with the GIS maps you can overlay layers of data that show the topography and hydrology data, as well as more updated satellite information that will show how much of the area has been paved, built upon, water diverted, ponds, dug, etc.

This information can really help in your decision making.

What you may discover is that - let's say your structures were built 20 years ago - when the area was not built up, or paved as much. Now, you see that with construction there is more runoff, more paved surfaces - and your hay shed may now be in the way of storm runoff. Or water backup.

If it's time to build a new hay shed....... you may decide it is wise to build it elsewhere. Or, take flood proofing measures.

Flood proofing can consist of really little tiny things that aren't terribly expensive, but can mitigate damage to structures, culverts, fencing, etc. It can also help preserve an evacuation route for your animals (and people). The placement of a gate on a level part of the pasture may be super - but if it's under water your animals may be trapped.

Elevating a structure, situating a structure so that water can pass through rather than push against the structure, installing electric at height so that it is not ruined by most flood waters, using materials that don't retain water or inhibit mold when wet (hardipanel, foam insulation, etc.)

It can make the difference between a ruined structure or a damaged one that can be repaired.

When I refer to structures within a floodplain - I am referring generally to ag structures. But also remember that people and developers can have homes or areas removed from Zone A through certain processes- which the current owner may not be aware of. So you are at risk of being flooded but you don't know it.

Also, structures not within a flood plain are still at risk of flooding, but the great thing is that flood insurance is not that expensive! So if you are concerned about flooding, runoff, backup - consider checking out your FEMA map, GIS maps, and then have a chat with your insurance agent. Even if you purchase a very modest amount of flood insurance, your barn, arena, or other structures may have a bit of protection.

If anyone is interested, you can sign up for updates from FEMA as they go through the mapmaking process. For those who live near water (even a creek), you may find it very educational.

A good search term to Google is "flood proofing". Here is a link for flood proofing from FEMA - but do an Internet search and you'll find loads of great information. http://www.fema.gov/rebuild/mat/rfit.shtm

LMH - I think this last link might just be the thing you're looking for - check out the table of contents.

Sorry for the long post - hope the information is useful to someone.

Gryhnd
Sep. 25, 2009, 03:12 PM
Just to address your question of cost of a bridge, we paid close to 5k for something we can take vehicles over.
We found someone that builds metal buildings and he had two used steel H beams for sale, about 32 ft long if I remember correctly. He brought them here and laid them down with a crane.
A separate guy and his crew had already prepared the ground. They dug out an area on each side of the creek (trying not to disturb the bank) and set concrete blocks for the beams to rest on, then concreted that area in, then built wood bridge on top of that. The first layer of wood runs parallel to the creek, horizontal, and then he added a second vertical layer over the area where the beams are, for driving support purposes.

I suppose you could do the wood work yourself, just too much for us to handle. This creekbed is lined on both sides by very large trees, we had to pick the one spot where the trees weren't quite as thick. Also, it is probably at least 8' from the top of the bridge to the bottom of the creek, looks more like a big ditch in the ground than a pretty creek, unfortunately.

Mostly we take the Mule or the tractor over it (well, mostly walk over it actually, our house is on one side of it and the horse pasture/barn on the other - there is another way around, this is just shortest).
We had trouble with the whole thing, finding anyone to do it, finding materials, etc. We just pray it never gets knocked out, the water hasn't come up that high in the past but who knows. This creek is dry 99.5% of the time, but acts like a flashflood at certain times, has done alot of damage around the property including at another bridge that does have 2 culverts under it (also for driving vehicles over).

cindylouwho
Sep. 25, 2009, 03:16 PM
I work for a bridge building company and don't have a drive across bridge at home:) We can't build a 50' bridge for under about $30,000! Most of our projects are state bridges, but because we are union our labor costs don't go down on private work.

Tom King
Sep. 25, 2009, 04:27 PM
A person I know had the same problem. He had several culverts wash out and they were very large concrete pipe. The span was maybe 35 to 40'. I suggested he buy a couple of cheap semi trailer flatbeds that the running gear had worn out on. He found a couple at a semi truck salvage yard, welded them together side to side, and as far as I know his "bridge" is still there a couple of decades later.

poltroon
Sep. 25, 2009, 04:33 PM
JSwan, that's wonderful info and very useful. I discovered recently that the FEMA maps for my property are wildly and importantly inaccurate because they were drawn based on aerial photography. If there was a tree, they assumed it was at the lower elevation of the creek to the edge of the drip line...

I think a bridge suitable for driving of any significant length is going to be a five figure proposition. There are companies that convert railroad flatcars into bridges - that is about the cheapest option - but even those can run in the $20k range.

poltroon
Sep. 25, 2009, 04:37 PM
JSwan: how do I sign up for the updates?

And the maps have edges for their "100 year flood" lines, but on mine, there are no elevations for that water level. Any ideas on how to find that data? I'm wondering if the road people will know what that elevation is relative to their bridge, for example.

Bluey
Sep. 25, 2009, 04:42 PM
Could you do what we do here, get the bulldozer and make a road down to the bottom and out of there on the other side.
If the bottom is very sticky, pour some concrete down there.:)

I have made some ranch feed roads like that, minus the concrete at the bottom, in several of our canyons, some are a good 30' deep.

JSwan
Sep. 25, 2009, 05:32 PM
JSwan: how do I sign up for the updates?

And the maps have edges for their "100 year flood" lines, but on mine, there are no elevations for that water level. Any ideas on how to find that data? I'm wondering if the road people will know what that elevation is relative to their bridge, for example.

Oh - the Nav data goes back to the 1920's, I think. I think this is the link I used to sign up/check out updates. If this doesn't help check back and I'll look for something else. http://www.fema.gov/plan/prevent/fhm/st_main.shtm

If you want to see something interesting - check out railroad lines. You'll often see railroads at a higher elevation than country roads. Way way back, the roads were game trails. Then hunting paths. Then horse/carriage trails. Then dirt roads. Then gravel roads. Then paved roads. But they essentially follow the path of old game traces. When these old roads are "modernized", they are usually elevated, straightened, etc. That may not be true where you live - but the country roads were I live are very similar to the game traces/trails from the 1700's. You can compare old and new maps - it's pretty cool. Anyway - all the railroads lines are elevated - some by several feet. Even when they don't need to be - those railroad workers knew what they were doing!

Around here though - if we get too much rain we're stranded. No way out. Doesn't bother me but it's something to be aware of.

The maps were accurate enough in their time, but that line you see may have been drawn with a pen and represent 5 feet or 15 feet. Seems innocuous but it can mean the difference between a dry house/barn and one under 10 feet of water. It can also mean the difference between a hefty flood insurance premium and one that is very reasonable.

When installing culverts, especially on private land, calculating flow and velocity correctly can mean the difference between a flood or simply wet ground. For people rebuilding, putting in a larger culvert is a good idea - but if you really want to go a step further get ahold of an engineer or soil and water/erosion person and ask them for some math help. You'll want it to at least withstand a 10 year storm.

Others measures to slow velocity and capture silt can be the use of check dams, grassy swales, surge stone, and those are homeowner projects if the person wants to educate themselves. I always have to look up all the math and cheat that way because I can barely add. Math was never my strong suit.

Also - there is a way to dispute a flood map. Contrary to popular belief, this does not always require you hire an engineer, surveyor and perform a flood study. A landowner who believes the flood map is in error can file for a LOMA (Letter of Map Amendment). You do this for just the scenario you wrote about - a map that failed to take into account a hill or feature that renders the map inaccurate, among other things.

You can do that now - you don't need to wait on FEMA to get around to your community for revisions.

For a horse farm that brought in fill for an arena, or barn, or for other reasons - and believes that change brings that area out of Zone A - the LOMA-F is used to change the map. While this means you no longer need flood insurance - I'd still suggest you obtain it. It is really cheap if you're not in Zone A but Lordy if you ever have a Georgia type flood will you be glad you have it. Zone C can and does flood too.

Once the LOMA is issued a copy goes to local gov't and that information should make it into GIS. Don't hold your breath though - keep a copy! :lol:

I was just thinking how a person could estimate the cost of a bridge for LMH. I know insurance companies have a square footage figure for homes, but I don't know if they have such a thing for other structures. Anyone know?

LMH
Sep. 25, 2009, 06:11 PM
WOW this is turning into a wealth of information!

Thank you to everyone!

suz
Sep. 25, 2009, 06:39 PM
if you live in snowmobile country, try finding someone who builds snowmobile trails. around here they build plenty of bridges and we had one built for us.
our site is a steep and deep ravine over a fast moving year round brook, we're lucky we have that steep and deep place to build it.
now, our builder turned out to be a thief, but the bridge is a pretty good bridge and after ten years we had a local builder cover it, so we now have a nice covered bridge in our backyard. since we're in vermont it looks pretty nice.

poltroon
Sep. 25, 2009, 06:51 PM
Also - there is a way to dispute a flood map. Contrary to popular belief, this does not always require you hire an engineer, surveyor and perform a flood study. A landowner who believes the flood map is in error can file for a LOMA (Letter of Map Amendment). You do this for just the scenario you wrote about - a map that failed to take into account a hill or feature that renders the map inaccurate, among other things.

You can do that now - you don't need to wait on FEMA to get around to your community for revisions.

For a horse farm that brought in fill for an arena, or barn, or for other reasons - and believes that change brings that area out of Zone A - the LOMA-F is used to change the map. While this means you no longer need flood insurance - I'd still suggest you obtain it. It is really cheap if you're not in Zone A but Lordy if you ever have a Georgia type flood will you be glad you have it. Zone C can and does flood too.

Once the LOMA is issued a copy goes to local gov't and that information should make it into GIS. Don't hold your breath though - keep a copy! :lol:

Ohhh, sweet JSwan! This is just the kind of information I needed. My hero!!

JSwan
Sep. 25, 2009, 07:09 PM
Ohhh, sweet JSwan! This is just the kind of information I needed. My hero!!

My good deed for the day, I guess. :lol:

wildlifer
Sep. 25, 2009, 08:04 PM
I didn't get a chance to read all the responses, but I do hope you get to put in a bridge -- it is far better for the health of the stream than a culvert.

Romany
Sep. 25, 2009, 09:04 PM
I didn't get a chance to read all the responses, but I do hope you get to put in a bridge -- it is far better for the health of the stream than a culvert.

How so? Just curious, as we re-set a couple of washed-out old culverts this summer. Mind you, our "stream" is more just spring run-off, although it's heaving with tiny leaping sticklebacks every spring. Where they go when it dries up by mid-summer, I have no clue.