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Culvert installation into running streambed

Culvert installation into running streambed

(OP)
We would like to install a culvert in a running streambed, in order to provide better access to a back lot on a farm.

The stream is small, I don't know flow rates, etc, but I would say it is 2 inches deep, 18" wide, at the most. The flow rate doesn't appear to change dramatically, even after large rains, as the stream originates not far from where we need to cross and isn't fed by a major run-off.

The creek bed is somewhat marshy, with really solid soil starting about 5' on either side. This is the best point for crossing, otherwise we'd try to find a place with drier surrounds.

With that context, we are curious to know what we should do to stabilize the creek bed prior to installing the culvert. The culvert size we are planning to install is 36". Should we put a certain kind of gravel in? Should we install the culvert parallel to the stream and then divert the stream to flow through the culvert, giving us a drier working area? Should we surround the culvert with gravel, or just backfill with soil from the vicinity? How much soil should we cover the culvert with in order to cross the culvert with heavy farm equipment, including excavators?

Any advice is greatly appreciated, as this is a DIY project and we don't have much experience.

RE: Culvert installation into running streambed

What material is the 36" culvert made of?  If reinforced concrete pipe is used and the wall strength is similar to Type 3, then dig down 18" below the flowline of the creek and place 6" to 12" of sand/gravel for a base.  Place the pipe lengths, (width of road plus 9' for slope), and fill to the top of the pipe.  A foot of well compacted fill, (original soil), above the top of culvert and then a 4" gravel road should suffice.  Head walls can shorten the required length of pipe culvert and extra fill on top of the culvert can allow substituting CMP for the culvert.

RE: Culvert installation into running streambed

(OP)
Thanks for your response!

The culvert is metal, so we'll add extra fill over the pipe. Also, how much lower than the stream should the metal pipe be inserted? Would it still be 18" below the flowline?

RE: Culvert installation into running streambed

With your topography and hydrology/flow conditions, will this have to be a "siphon"?

RE: Culvert installation into running streambed

(OP)
Can you explain more about what you mean by "will this be a siphon?", at least in this context. Do you mean drain the water out first?

We are currently planning to dig a new trench for the culvert and then redirect the stream through it, once installed, so that we aren't working in the mud.

RE: Culvert installation into running streambed

Not to rain on your parade, but you likely need a permit to do this work.  Streams are protected just like wetlands and your state environmental agency and/or the Corps of Engineers may be involved.  Also, you may face the need for mitigation for the impacted section of stream/wetlands, which can get expensive!

f-d

¡papá gordo ain't no madre flaca!

RE: Culvert installation into running streambed

I guess I originally misunderstood what you meant (I now understand better that you are just wanting to build an access in effect ROAD "crossing" to bridge over a stream, which means the stream basically WILL flow through the culvert you are talking about!)  

RE: Culvert installation into running streambed

recommend the culvert should be installed at the same level as the existing stream. If you lower it, it may just fill in with sediment anyway. However, if you are using a 36" culvert to cross an 18" wide stream, you could bury the culvert below grade and still handle the runoff. What kind of traffic will be crossing the culvert? Nobody has asked this question which is quite important to know what the live loading is on a shallow culvert. If you intend to drive over this with heavier equipment, trucks, tractors etc you may want to increase the depth of fill over the top as well as to use a good quality material for the fill. 12" of native and 4" of gravel as suggested may be fine for light auto traffic, assuming that your native material is decent. But will not be suitable for heavier traffic.

RE: Culvert installation into running streambed

I concur with cvg and civilperson for the most part.

36" CMP (corrigated metal pipe) is what I am picturing to be used to provide a crossing over a running stream.

RCP would be better if your loads are sizeable.  I would (temp.)divert the stream (or temp. dam if poss.) place 3"-6" inch aggr., and walk it down if possible, to accomodate the btm. of the new pipe (FL) to be at or below your existing creek btm. (install pipe in existing creek bed)
The large aggr. has worked well in the past for single and multiple RCP's.

I would not expect you to encounter Environmental issues (USACE, regulatory agencies, or otherwise) unless you are performimg this work for someone other than a private individual. You should however stabilize (perenial vegetation) all fill materials exposed to the stream.

If you are subject to environmental scrutiny, backfill the pipe with non-erodible material (aggregate) up to a point above the area(s) that are in contact with the stream then begin normal fill operations. The stream is considered waters of the US, however regulatory agencies (at least around here) do not "usually" approach folks on their own property.
Sounds like you are in a rural area.
Sloped ends are nice additions to this type of crossing.

Happy Trails

RE: Culvert installation into running streambed

Your environmental exposure has more to do with any downstream neighbors that may notice turbidity in their portion of the stream during this work. If they react (i.e., call the regulator), you will have an issue on your hands.  It doesn't matter whether you are working on your land or not!

I don't make the laws, but they can bother a project like this just as easily as a big commercial job.

f-d

¡papá gordo ain't no madre flaca!

RE: Culvert installation into running streambed

(OP)
Thanks everyone for your responses. Much appreciated!

We are in a rural area and have looked into the rules re: stream crossings. It seems that agricultural purposes end up incurring much more lenient rules than residential, so hopefully we will be ok by the law.

Re: the crossing weight. Most of the time the culvert will be crossed with pickup trucks and tractors, however, we are hoping to also be able to cross with excavators, which can get very heavy; though this would be rare. We've already purchased the pipe and put it in the streambed, but have not backfilled yet. Is the combination of our crossing load requirements and metal pipe not feasible? Must we use concrete pipe? Can we mitigate the weight issue by adding more fill on top? What sort of material should be used for backfill/over the top in order to provide the most strength?

Thanks again.

RE: Culvert installation into running streambed

Fattdad mentioned that USACE will need to be involved, I believe the permit you need is a Nationwide #39.

Regarding mitigation, if the creek is considered habitat or supports fish life, you may want to consider adding a course of streambed material along the flow line of the culvert. This will require to oversize the culvert and install it deeper so you can match the existing flowline. Contact your local fish-and-game office to learn more.



RE: Culvert installation into running streambed

(OP)
Thanks for the feedback re: permits. We are looking into this more on your advice.

RE: Culvert installation into running streambed

there is nothing wrong with corrugated metal pipe, even for large equipment. however, you will need to make sure you do a good job compacting around the haunches of the pipe, use a good quality structural backfill (not the muck that you pulled out of the stream), and then additional fill over the top of the culvert to spread the load better. Expect that the culvert may deflect when you cross it with the larger vehicles. For backfill and fill material, I would use DOT grade, crushed aggregate road base material.  

RE: Culvert installation into running streambed

(OP)
cvg: By "good quality structural backfill", do you mean we need to use crushed aggregate, or good quality soil? We had planned to transfer soil from an area nearby, but that is in good shape (not marshy/muddy soil). I thought that the fill, near the haunches, should not be crushed aggregate (though that had been my first idea)?

We do plan to put a good top layer of crushed aggregate.

RE: Culvert installation into running streambed

I don't know what your soil conditions are, maybe your native soils are good. But native soils are rarely as good as road base which is probably what I would specify if I was designing this culvert for one of my clients. For additional strength with heavy loads, I would use a flowable concrete backfill. For flexible pipe installation such as your steel pipe, the backfill and compaction is an essential part of the installation.  If you skimp on this, you may eventually need to replace the pipe when it fails.

RE: Culvert installation into running streambed

(OP)
Could you describe what good soil would be? We have two kinds, a red, clay-like, soil, and a brown topsoil. We were planning to use the red soil.

RE: Culvert installation into running streambed

(OP)
If we go with road base, should we use it all the way up the culvert, from the current streambed level, or start higher up the culvert's side?

Thanks again for your feedback.

RE: Culvert installation into running streambed

Either of your soil types will work if placed in thin level layers and compacted.  Use 4-6" lifts and ram with the end of a two by four or rent a jumping jack tamper.  The portion of the pipe resting on the grade needs support so excavate the trench to match the bottom third of the pipe.  Keep the moisture of the fill damp enough to hold in a clump after squeezing.

RE: Culvert installation into running streambed

(OP)
That's a great document; thanks for the link.

RE: Culvert installation into running streambed

yes  fatdad

If this work is upstream from some folks who like to call regulatory agencies perhaps rogerrogers may get some company.

But surely placing a CMP in to cross a stream would not warrant corps involvement, "mitigation", Individual Permit. Come on.

If farmers got the agencies involved everytime they put a cross pipe in it would be a little bit ridiculous, wouldn't it?






 

RE: Culvert installation into running streambed

I agree with cvg, use a good road grade backfill up to the haunches, well tamped into place. I use HDPE ("plastic") pipe under parking lots with truck loadings all the time, I specify that they throughly tamp the haunches. Agricultural activites are exempt from many wetlands / permitting requirements, especially if the upstream drainage area is minimal. Just put it in and stabilize everything as quickly as possible.  

RE: Culvert installation into running streambed

Be sure to repaint your yellow backhoe changing it to green. Then you will be be engaged in agriculture, NOT in construction.

RE: Culvert installation into running streambed

Quote:

But surely placing a CMP in to cross a stream would not warrant corps involvement, "mitigation", Individual Permit. Come on.

Not so harsh please.  We don't know what state the OP is in, we don't have any drawings, the idea of a stream crossing for an excavator and multiple culverts may imply something that has some width and there could be associated wetlands in the riparian buffer.  Then again, I may be incorrect.  I brought up the topic, but it doesn't feel right to be seemingly discredited.  You can take any position you want and it's fine with me.

Regarding the pipe backfill:  The service load from trucks, excavators and the like are not supported by the pipe, per se.  There is load transferred to the pipe and for the pipe to deform the soil on the sides of the pipe has to yield.  Folks have already mentioned that the intimate contact of the compacted backfill below the spring line is critical.  So, if you don't have a stable subgrade and muddy conditions at or below the haunches, you'll be inviting problems.  Another consideration is the amount of soil fill above the top of the pipe.  Several feet being much better than several inches and such.

Regarding agricultural work v. commercial work - not sure of the distinctions in the eyes of the local environmental agencies and the US Corps of Engineers.  If permitting is required there may be some state permit or nationwide permit to assist (i.e., simplify).

Good luck.

f-d

¡papá gordo ain't no madre flaca!

RE: Culvert installation into running streambed

fat dad

My apologies sir, I should have included an emoticon. My intentions were non-malicious, but rather directed at my frustration towards the current regulatory agency process.

You are absolutely correct in directing the OP to local and federal guidelines regarding any construction that affects Waters of the U.S.  Hoagie mentioned a USACE nationwide 39; a nationwide 14 may be better suited for this work with regard to Notification requirements.   

Further more, you are also correct in stating the obvious about the unknown location of proposed culvert installment. Many states have more stringent rules about this type of work due to unique and apparent circumstances, which certainly is germane to this application.

The last 20 years I have witnessed large sums of money spent to satisfy someones interpretation of EPA guidelines.


banghead
 

RE: Culvert installation into running streambed

Drumchaser:  thanks for the reply - hope I wasn't too touchy, but cyberland is so different from real life, eh?

OP:  There's some good stuff to consider on this thread.  Hope it all helps and your project works out great!

f-d

¡papá gordo ain't no madre flaca!

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