Rip Rap/Sea Wall filter cloth

[jdlough]

Eastern shore, Chesapeake Bay, concrete column seawall. Storms come right at me.

My next door neighbor and I each have a concrete column seawall. His was getting chewed up. He paid $10,000 for a line of rip-rap rocks installed about 40 feet out into the water, parallel to his sea wall, with some sort of filter cloth installed within.

The idea is that water at high tide will break over his new rip rap, but the outgoing water would be slowed by the cloth, and deposit sand on his inland side. Then seagrasses establish themselves on his new sand.

Works great, for him.

For me, not too good. My sand is getting washed away. (Or he is getting the sand I would have had) I've already had a couple of concrete seawall 'teeth' fall over.

I priced getting the same thing done for me. $10,000 to get a line of rocks built up about 40 feet from my bulkhead. But, at low tide I see that at one time, 50 years ago, there was a line of rip rap rocks, but they are now spread all flat.

So, I figure instead of spending $10,000, I spend nothing and in my spare time, I will go out there at low tide with a crowbar hook thing, and just re-create my own rip rap line from the old spread-apart rocks. Except apparently the filter cloth is very important, to keep the outgoing current from taking away all my new sand.

BUT, I cannot find a source, or even a name, for the cloth I need. Maybe 4' to 6' by 200'

It can't be any weedblock stuff. It has to be strong.

Any ideas?

 

[Texasmark]

Re: Rip Rap/Sea Wall filter cloth

Go to the weed block mfgr and see if they have a wider product line. Ask them if they know of a supplier of what you want. Go to your state highway department and ask them if they use or know of anything that you can use. Go to the rock rack company and ask them. I think the rock rack is a super idea; down here anyway....course with a drought, yo don't need that stuff....for now anyway.

Mark

 

[jdlough]

Re: Rip Rap/Sea Wall filter cloth

FYI, rip-rap may be local terminology. Rip-rap means any line of rocks (usually between softball-sized, watermellon-sized, beer keg sized, or bigger), used to combat erosion. You may see rip-rap lining highways, drainage ditches, etc.

ALL bridge foundations underwater are surrounded by rip-rap. It slows the current enough so that the underlaying silt dosen't get washed away.

I have a bulkhead seawall, made by a line of vertical 2 feet by maybe 8 feet concrete pilings, lined in a row. Normally, it does fine. Unless the tide washes the sand out from under any of them. Then they begin to shift, or fall over like rotten teeth.

The line of rip-rap 40' out from the seawall is meant to slow the waves down enough in fair weather to deposit enough sand to protect the seawall in bad weather.

I need some really strong filter fabric to interweave within the rip-rap, so that it will slow down the outgoing tide/waves, and leave me with the sand, instead of taking the sand away.


Here's some pics of some minor bulkhead damage within my cove (taken at low tide), which I got fixed CHEAP for $1000. I'm now worried about the upcoming winter storms damage to the bulkhead at the point of the cove.

 

[EddiePetty]

Re: Rip Rap/Sea Wall filter cloth

Stop by your local VDOT/MDOT maintainence facility or railroad section shop. Both use that stuff around bridge and overpass 'rip-rap'.

I googled "beach erosion cloth' and got a zillion hits!!! HTH's

 

[jigngrub]

Re: Rip Rap/Sea Wall filter cloth

So, I figure instead of spending $10,000, I spend nothing and in my spare time, I will go out there at low tide with a crowbar hook thing, and just re-create my own rip rap line from the old spread-apart rocks. Except apparently the filter cloth is very important, to keep the outgoing current from taking away all my new sand.

BUT, I cannot find a source, or even a name, for the cloth I need. Maybe 4' to 6' by 200'

It can't be any weedblock stuff. It has to be strong.

Any ideas?

You're only going to make it worse by moving the rocks that're already there, this will cause more undermining and erosion. Leave your existing rocks alone!

Here's a link for some geotextile cloth:

http://factorydirectlandscape.com/index.php?option=com_content&view=article&id=19&Itemid=19

You need to add the cloth and more rip rap and not disturb what you already have.

 

[Bob_VT]

Re: Rip Rap/Sea Wall filter cloth

Do a search for Filter Fabric which is very common in road construction and comes in many materials and designs ....... The other "saving" feature used here in VT (No tidal activity but lots of ice activity) are Gabion Boxes. We use them along river's too.

I have installed them along turns in the river and they hold up great.

 

[Texasmark]

Re: Rip Rap/Sea Wall filter cloth

are Gabion Boxes. We use them along river's too.

I have installed them along turns in the river and they hold up great.

That's probably the name of what I was referring to....just a rectangular cube of heavy duty wire filled with rocks.

Mark

 

[DuckHunterJon]

Re: Rip Rap/Sea Wall filter cloth

If you have a friendly excavator, ask him for driveway fabric. It comes in 12' wide rolls, you could cut it down to your size. Might be able to get it cheaply.

 

[Home Cookin']

Re: Rip Rap/Sea Wall filter cloth

Be sure you have the proper permits for whatever you do. "They" are very tough about this stuff and won't hesitate to make you do it all over, and fine you in the meanwhile. They fly around and look for changes. As you have learned, anything you do affects your neighbors.

You also want to be sure the neighbors sign off on what you do. Right or wrong, they are likely to accuse your work of affecting their land.

Rip rap is sized by the size of the waves that will hit it; there is a formula.

If you use scrap material (broken up sidewalks, etc.) remember that concrete is relatively light. Nonetheless, consider dumping some at the base of your bulkhead.

The problem with an offshore groin or jetty is that you can't bring a boat up to your bulkhead. I don;t know if that matters. Consider whether you might build a pier out that way, too, and if your groin is going to be in the way.

 

[robert graham]

Re: Rip Rap/Sea Wall filter cloth

Check: Ten Cate Mirafi Geotextiles for lots of information. Ten Cate is a Dutch company who pretty much "wrote the book" on geotextile/erosion control fabrics. You should be able to buy the rolls of fabrics you need from one of their distributors. Soil stabilization and water/erosion control is a real science with some interesting and novel products and solutions. Good Luck!

 

[jdlough]

Re: Rip Rap/Sea Wall filter cloth

Thanks to all. "Geotextile" was the word I needed to do my Google searching. The driveway fabric idea seems promising. The Gabion box idea may be easiest http://en.wikipedia.org/wiki/Gabion but my wife thinks they are ugly. I may end up using a Gabion box for the base, and piling the old rip-rap on top.

I called the powers-that-be. They were actually helpful. They want to encourage folks to build these rip-rap walls just under the high tide line about 30' out from the bulkheads, to collect sand and promote sea grass growing areas. The catch is that the cheapest permit is $750. I explained that I just wanted to collect and re-pile up the old rip-rap line, that years ago collapsed and spread around a bit. They say that they are quite sure I won't need a permit just to fix the old rip-rap, and are coming out to inspect and give me an inspection form and Army Corps of Engineer forms giving me the OK. They also have plans and diagrams and some contacts for rip-rap contractors and geotextile suppliers. This is not complicated. Waves bread over the rip-rap, outgoing water is slowed by the filter cloth, sand is deposited between the rip-rap and my bulkhead, sea grasses grow there. Wetlands increase. Erosion is halted. Crabs get a nice place to make baby crabs. Everybody's happy.

Here's a pic from my pier, at low tide. At high tide or during storms, the waves break over the bulkhead onto my lawn. Only the strongest weeds survive. After a really big storm a couple of years ago, I found jellyfish washed up on my back steps. You can see the spread out old rip-right to the right. On the left, you can see that I started assembling and reforming the old rip-rap line. Heavy rocks covered with sharp barnacles.
(Click to embiggen)

 

[DuckHunterJon]

Re: Rip Rap/Sea Wall filter cloth

Nice house and beautiful location.

I don't have a ton of experience in this area, but from the little I do know - can you get bigger rip rap in there? The couple of shoreline reinforcements I've done, we set what we called rip rap in one rock at a time with a large excavator. They were 3-5' in diameter rocks. Then again, we have to deal with a couple feet of ice moving things around. Just a thought, probably not a very good one.

 

[Home Cookin']

Re: Rip Rap/Sea Wall filter cloth

generally speaking, you can often repair/replace/maintain existing structure and dredging without a permit or without a challenge getting one, but still you want to check as you did, Sounds encouraging. With environmental authorities, unlike your wife, you do NOT want to ask for forgiveness instead of permission!

And I like your new word "embiggen".