a land bridge

L. Wakefield · June 11, 2004, 08:22:31 AM

   I am not sure if this would be better in 'logging methods'- but here goes..

   We have a little 'gut'- a slowly moving brooklet/swamp area that has had a 'land bridge' crossing it since I was a little kid. I am going to reclaim it- there are old logs at the base, and stones above- the water filters thru unimpeded finding its own way. I think it will be OK for human or cattle (the cattle have eroded the approahes but I know how to fix that).

   But that's not my real point. Mike wants to go upstream of it and build *another* land bridge but also with a catch basin behind it. He is thinking of putting a single culvet for drainage.

   Meanwhile I have my mental pix of the crossings down in WV where they put concrete either with multiple small pipes or open drains on top- they called them 'submarine bridges'.

   I am not at all convinced that the single culvert design is amenable in this case where he is starting with a swampy drainage area.

   A good while ago I got a copy of 'A Landowner's guide to building forest access roads' from the USDA. It's NE area-specific.

   The closest thing to what I am visualizing is under 'wetland forest roads', specifically 'crossing shallow and deep peat wetlands'. They show drainages that seem to be designed much as the old landbridge was- to let water flow thru unimpeded.

   I guess part of the difference of opinion is that Mike specifically *wants* to impede flow to the exptent that he gets his little pond. But I am just thinking that the water will not take kindly to the notion that after all these years it has to go "only" thru the culvert. There is a meandering type of strambed that is the rough size of a culvert bu there is all this muck too. Hmm..

   I could post measurements here. any thoughts or experience with this? lw

Tom · June 11, 2004, 08:33:55 AM

I use a culvert to cross a wet-weather creek behind the house. It is in an area much as you describe. The important thing is to use a culvert that is large enough for the maximum flow of water.

I couldln't believe the amount of water that would accumulate behind my bridge (dam) when we had a wet season. Starting with an 18" culvert, I soon was up to 30": and even put a couple of smaller ones toward the sides of the bridge, just in case.

I've not had the bridge blown out yet but there were times that I thought it would I have had water flow over the top.

I'm sure Mike can build one that will act as an overflow for a pond. Just make sure you can handle the water. Full 30" pipes are a bit scarey.

SwampDonkey · June 11, 2004, 10:13:39 AM

LW:

Since you brought up the topic of forest roads and stream crossings I checked my forestry links and low and behold. For landowners resident in Nova Scotia, you may be interested that the Forest Products Association administers a road access/maintenance program, funded by government. We used to have a similar program in New Brunswick, but it was Federal. In Nova Scotia the program is labled 'Access Road Program'. 8)

Link here

LW: I also found a reference to the USDA literature on forest roads at the www.woodlotinfoshop.ca

Good luck with your stream crossing.

cheers

Ed · June 11, 2004, 10:24:58 AM

Hi y'all,
I'm new here, this is a really great forum. You seem to have a lot of good people here.
I can't give you a lot of help on your qusetion, so I'll offer just a little. If you end up using a culvert in the "marshy" area, over time its gonna settle. You start with a 30" & in a few years its down to a 20". There are "egg" shaped (flat bottom) culverts available but I don't know the sizes. The type / ammount of traffic over it will make a big difference also. If most of the traffic is cattle, thats a lot of concentrated weight on those hooves.
Just more to consider, but I assume you only want to do it once.

SwampDonkey · June 11, 2004, 11:35:36 AM

Wecome to the forum special ed. Glad you are impressed with the forum.

Those are good points to keep in mind: 1) application 2) frequency of use 3)size of culvert and 4) weight of load. ;)

cheers 8)

L. Wakefield · June 12, 2004, 04:58:14 AM

Thank you all for your answers.

Going back to the first response- yes, that was what I pictured- times of high flow and restrictions. The water now seems to percolate along as well as go thru the 'channel'. The use of several smaller diam openings (or the filtering rock concept) diffuses that potential bottleneck. lw

L. Wakefield · June 12, 2004, 04:59:32 AM

QuoteI use a culvert to cross a wet-weather creek behind the house. It is in an area much as you describe. The important thing is to use a culvert that is large enough for the maximum flow of water.

I couldln't believe the amount of water that would accumulate behind my bridge (dam) when we had a wet season. Starting with an 18" culvert, I soon was up to 30": and even put a couple of smaller ones toward the sides of the bridge, just in case.

I've not had the bridge blown out yet but there were times that I thought it would I have had water flow over the top.

I'm sure Mike can build one that will act as an overflow for a pond. Just make sure you can handle the water. Full 30" pipes are a bit scarey.

When you say 'wet weather creek' do you mean one that flows only in wet weather- dry at other times? lw

SwampDonkey · June 12, 2004, 06:01:33 AM

INTERMITTANT ;)

Tom · June 12, 2004, 07:39:47 AM

Yep, LW. It is boggy most all of the time and runs in wet weather, being fed from a little "head" (swamp) just north of my place. Because is stays so soft, I had to do something to be able to cross it regularly without tearing it up. I chose dirt for a bridge because it was so wide. The main channel being the deepest and only about 6 feet wide, the rest is quite shallow but runs for a length of 150 feet. Thats a lot of water when it fills up. More than I figured it would be at first. I went to school real quick. :D

Gary_C · June 12, 2004, 11:50:38 AM

LW

I have a "guideline " book titled "Sustaining Minnesota Forest Resources" that has the same section of "wetland forest roads." My book cautions that you must contact the DNR or Soil Conservation Office before doing any work and many times you need a permit. However in Appendix H there is a list of circumstances where you do not need a permit.

I have found that it is best to talk to the DNR or whoever it is in your state first as they get very mad if you do the work first and may even fine you and make you take it out altogether. They are usually easier to work with when they are not mad and can sometimes be very helpful and show you the easiest way. I would doubt very much that you will be allowed to change the level to create a pond.

I am going to be doing the same thing this summer for a job I will be starting this fall. We originally had a 24" culvert but that will take too much fill to get over the top. Now we will use a 14" or 16" and use some of that road fabric to stabilize the fill. Stabilizing the fill so you can use it when it's wet will be the biggest problem, but not if you can use concrete.

Gary

SwampDonkey · June 12, 2004, 12:00:44 PM

Here in New Brunswick you have to apply for a Watercourse Alteration permit from the Dept of Environment and Local Government. (Clean water Act). Or you can notify a Certified watercourse supervisor, which can be expensive, but if you need the work done right away, that is an option. They will do all the paper work and submissions to DOE. Most folks will submit their own application on private land. And the Act stipulates that a minimum of 18 inch diameter culvert is to be used. If its a bridge your constructing they will want to see plan sketches, maps and photos. If its a small stream, they want maps and aerial photos. Alot of those small crossings they never even come to see. Not enough man power. I have links to all this info on my watershed management page.

cheers

Gary_C · June 12, 2004, 12:57:03 PM

Keep in mind, there is a big difference between a stream, creek, or any place where water is flowing and a wetland crossing where the soil is saturated but water is not normally flowing.

On the job I have coming up, we are fixing an old log corduroy drainage system with a culvert. The water does not flow thru there normally but can in wet conditions. Below there is just scrub brush. There is a stream less than 100 yds beyond that takes whatever flows out of the wetland but if we created a channel thru there and lowered the level of the wetland, we would probably get free room and board for some years. Same is true if we obstructed the flow in any way and raised the water level in the wetlands.

No stream crossing or other permit is required for my job.

Ron Scott · June 14, 2004, 07:42:21 PM

Yes, its best to check with your State DEQ, Conservation District,etc with your objectives of what you would like to do in the wetland or stream course. Permits are often needed, but they have defined "Best Management Practices" with manuals, plans, diagrams, etc. that may be specific and helpful for your situation.

Permits are usually needed whenever a forest road is involved with a stream or wetland crossing.

Rocky_J · June 14, 2004, 07:48:02 PM

Geez, I hate getting some gummint pencil-pusher involved in something on my own property and not affecting anyone else. Besides, it's usually easier to ask forgiveness than permission.

Do it right and hope the pencil pushers don't notice. If they find out about it before you do it, you will be hiring architects and submitting plans and paying fees and having some moron from 100 miles away deciding what materials you must use and how many bolts of what length and grade to hold it together. By the time they get through with you it would have been easier and cheaper to pour a concrete runway over it.

L. Wakefield · June 15, 2004, 12:53:34 PM

   Which-er- *is* a thought.

   'Upstream'- this is indeed only a seasonal rivulet- I took nice piece of gripstrut- about 12' long, 4'wide. already had nice edge reinforcement to it- and tipped it over to span the area. It works great for a people bridge, and little did I know that the 4 balls-y little calves we had this year would use it too. They just waltz across it like it's nothing- the older cows have nothing to do with such an artificial construct.

   cows crack me up. :D :D :D lw

etat · June 15, 2004, 03:29:38 PM

I like cows!

SwampDonkey · June 15, 2004, 05:47:17 PM

I like cows also, but someone else can look after'm. ;)

Frickman · June 15, 2004, 07:16:43 PM

A few years ago one of the locals here wanted to bridge a small stream, right in sight of the main road. They figured out that is was easier and cheaper to ask for forgiveness than permission, so they just put it in. They did a real nice, professional looking job, steel beams, concrete, and everything. Noone has ever said a word, but if they do, the fine will be cheaper than the permit.

Engineer · June 15, 2004, 08:35:49 PM

I do that stuff for a livin' (civil engineering/stormwater/wetlands stuff), and my first thought was a culvert. But, the marshy bits will tend to 'absorb' a culvert over time, and it will stop working to capacity.

Here's a thought - big rocks placed in the marshy area, then place smaller rocks on top of that, then smaller rocks, then smaller, etc. you get the picture. The water percolates through the stone, and by the time you get 2-3 feet above the level of the muck, you can place a single or double small culvert, maybe 8-12", just below the road surface. The rocks don't have to be too big, maybe 12-18" dia. for the bottom layer, then 6-8" stones to fill in the gap, and 2-4" stone for the top layer. They tend to fill in the holes in each subsequent layer. Settlement isn't a problem because the water will still percolate, and you have the culverts above the level of the muck to handle the overflow in high runoff seasons. Worst case, it flows over the stone.

My driveway culvert is built like that, and I had 12" of water flowing over it two weeks ago for a six hour period. Some of the little stones and sand washed away but not much.

JetMaxx · June 16, 2004, 02:21:24 PM

Engineer,
Your layout sounds very familiar to what's been suggested to us in crossing a wetland area in the front of our property. Should the wet area be dredged prior to putting in the large rocks as a base?
Also, the guy we hired to get the wetland permit suggested 24" stone as a base in this area, although the water doesn't move much through there.
Does it matter what kind of stone is used as the base? The reason for my question is that we have tons of sizeable round rocks on this property and I thought that we could put these to good use by using some as the base for this part of the driveway.

Engineer · June 16, 2004, 03:07:23 PM

24" rocks are fine, round rocks are great becuse they naturally leave gaps between themselves for the water to flow. I would not dredge, just drop the rocks in the muck.

Above all, make sure you either have all your necessary permits, or have checked to make sure you don't need a permit. Here in VT, you'd be surprised what kind of ca-ca you can get yourself mired in, legal-wise, just by dropping rocks in a "wetland".

JetMaxx · June 16, 2004, 03:29:10 PM

Thanks for your reply. Just a thought....won't there be some settling of the rocks over time if it's not dredged?

Regarding the necessary permits, I sense the same in NH. No work has been done yet but the wetlands permit should be in hand in a month or two. Once it's in place work will begin on the driveway and we can start taking out the timber as well. Hate seeing the warm months go by waiting for the permit but that's how it goes.