Culvert Extension On Slope

Trencher

First, I want to apologize for these images on a sunny day when the perspective isn't all that good; should have waited for an overcast day.

The top of the image is actually the road 20 feet below the work area. The dimensions are 20ft wide x 12ft out(to the edge of existing slope, which is at the top of the vertical arrow) x 8 feet deep (45 degree erroded slope). The slope is almost completely vertical with trees serving as the only rebar to hold it all together.

~There is no barrier wall to hold back the fill dirt once I start getting height/depth to it.
~I will need to fish out the most of the concrete chuncks so the 30 yards fill sand can settle between them for a more solid base.
~Drive 1 inch rebar stakes ( 6 feet long into ground level to tie in fill (like concrete jointing)
~ Once the sand is high enough to support the culvert, and temped enough for minimal settling, I will then use 100 yards of clean fill dirt.
~Re-inforce the constructed wall with anchor tie-downs (same used on mobile homes) with 2 tensile straps running from anchors to edge of fill.
~The straps are then linked through a chain link fence serving as revetment along with a weed blok tarp to keep sifting sand from, well, sifting.
~As I bring the level up I will add another strap and anchor (Same concept as approches to bridges when tensile straps are linked to each side of the approach and dirt is filled on top to hold the shoring wall wafers).
~Fill will exceed the existing grade of "good" ground as to not errode work area.

This existing culvert is to be extended out to the road in order to cease the errosion and to gain 8 feet of usable ground.











In a perfect world I would be able to drive sheet piling to fill against, but that is completely out of the question.

Oh yeah, this is in town and the "Hysterical Society" will be breathing down my neck.

Would anyone possibly have some suggestions as to anything I may have missed or another method of shoring this up so the fill will be sound?


Thanks guys!

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rino1494

Why use fill, why not just use rip rap. That way you don't have to worry about any dirt washing away. Also, it will help to hold the bank better.

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Trencher

I have to extend the culvert out another 10 -12 feet and it needs to be supported properly and then be filled to grade, with dirt, so the land can be enlarged and usable.

Rip rap would crush the fiberglass culvert and it is also not readily available in my area (south Louisiana) without extra costs the customer is not willing to pay.

Thanks rino,

Allen

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rino1494

The last detention basin we constructed, I made my own R-5 rip rap for the outlet just from the rocks around me. God I hate rocks.

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TMatt142

Is that a road down below the culvert?? Or is it just flat ground? Remember, the longer the distance the water has to travel down a hill, the more likely erosion will happen. If the water from the culvert just disperses down at the bottom on the flat ground below, put a 45 degree elbow on the end of the existing culvert, run the length of the slope to the bottom, then 45 out at the bottom far enough to get past the toe of your slope. Then fill your slope......Take all that existing "rip-rap" and dig a bowl out in front of your new pipe outlet, make sure the bowl is a half a foot to a foot below the flow line at the bottom, and throw your rip-rap down there to prevent any erosion at the bottom. I may be way off here cause there are limited photos, but bringing a culvert straight out on a slope like that usually makes for nasty erosion problems........purely my perspective on this........just trying to help.

Trencher

TMatt,

Yes, that is a road at the bottom of the slope. The road itself is on a decline. It is situated 6-8 feet from the slope. The ditch is lined with coarsely pour concrete. The culvert will be 12 feet, or more, above the ditch.
The builder wants to put an open-ended 45 on the end and that is it. However, with the 45 degree fitting costing $500 he will not be too apt in going with one. There should, indeed, be a drop line installed to reduce the impact of errosion.

I will have to get better pictures of it to give you a better perspective of it.

Thanks for the help.

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tgeb

I was going to suggest a drop pipe like recommended above and also a head wall at the bottom which would help hold back the slope.

But if this guy won't blow $500 on pipe fittings, I am sure the head wall would be way out of reach.

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