rip-rap: good or bad

[goose70]

The barge carrying huge amounts of rip-rap that hit the bridge got me thinking again about this topic.

I'm confused about whether rip-rap is good or bad for the environment, or whether its environmental impact depends on the specific characteristics of the shoreline. The Severn River shoreline, for example, seems to be "armored" significantly more each year due to what appears to be rubber-stamp approval for any riparian property owner to lay rip-rap along his shoreline. I counted at least 14 places where this occurred just last year. Several of these places were in relatively quiet coves along shoreline that contained grass, so I wonder why the rip-rap would be necessary (it certainly ruined the once-scenic areas). In Round Bay, an area with more wave action, the rip-rap placed in one location last year caused a violent wave echo effect that drastically muddied the water and tore out a once thriving grass bed.

I appreciate that as boats become larger and more numerous, shoreline erosion can be a real issue. But I also thought that a study done after Isabel found that shoreline erosion was less severe along vegetated shoreline, as opposed to bulkheaded to rip-rapped shoreline. A third, hybrid, approach was employed by the Fairwinds on the Severn community about 15 years ago and seemed to work (although I haven't seen it in years). There, the rip-rap was placed just under the water (about 6 feet off the beech) and shore grasses were planted behind the rip-rap. Does anyone know how this method's effectiveness compares to traditional rip-rapping?

Thanks for any info that you can offer.

[Tom Powers]

A fellow from VIMS did a talk at a CBF green breakfast that I attended last year regarding rip-rap versus a more natural grass shoreline. My impression was that the natural shoreline had a more diverse population, etc. There was a seminar at William and Mary last Friday that I wish I had known about in advance. Here is the link to all of the talks.

http://ccrm.vims.edu/seminarpresentations/spring2006/tidalwetlandswkshp1.html

Here is one interesting talk that addresses your concern.

http://ccrm.vims.edu/seminarpresentations/spring2006/Living%20Shorelines.htm

Tom

[goose70]

Thanks very much. Very interesting slide show. The slide's don't indicate the cost difference in the methods (or how the cost compares to traditional shoreline riprap), but if the cost is similar, I wonder why most of the (presumably approved) riprapping appears to be of the traditional, harmful variety? Are the authorities who approve shoreline ripap unaware of the alternative methods? (I find that hard to believe.)

[Capt Frank]

Having inspected bulkheads both stone and timber, stone revetments are suppose to outlast the former. Ive spoken to the Wetland Permit writers regarding same and the theory is that stone provides an environ where crabs and finfish can propogate, as well as create an armored slope where sediments are trapped thru tidal and wake action. As you may know, most of the Bay's creeks, tribs were tidal marsh before the shoreline was bulkheaded. In Md there is a channelward limit on the revetment under the General permit, something like 10ft, > 10 ft requires a more comprehensive Wetlands License. Having lived on the water for 23 yrs(with a stone wall bulkhead), Ive noticed an increase in fish, on an adjacent property where the neighbor had a revetment installed 5 yrs ago, creating a fish habitat. The negative is that it's a little tough on the feet walking along the shoreline. Ive seen some really bad revetment jobs where the stone was wavy on the slope and good ones where the stone kinda fit like a puzzle, and was not an eyesore.
The State does permit in kind bulkhead replacement. However, if no bulkhead existed previously, usually only stone is permitted.

Id be interested in the study you have indicating more erosion after Isabelle. I'll show it to the Permit writers. Ive noticed some erosion behind bulkheads where the fill was not properly compacted, emplacement of poor soils or failure to vegetate and stabilize. Its more important to have compaction behind revetment, esp when the bulkhead is inundated( filter cloth is used behind both bulkheads at any rate). But then again, Isabelle was most probably, a once in a lifetime event.
Hope that helps.......

[mikie]

I don't have rip rap or bulkhead on my shore, just naturally occuring vegetation. My shoreline has eroded at least 4' since I have lived here (20 yrs). I live on a small, quiet creek - only problem being the people that live here going by with jet skis, etc.. The property markers at the waters edge are actually about 20' out in the creek according to recent surveys (original survey in the early '70s). People on each side have bulkheads, which definitely doesn't help my property. So what's the solution? From my point of view, I like the natural shoreline - only problem is, it keeps disappearing. I think in the long run, rip rap has to be the answer.

[Capt Frank]

Sounds like you will need a revetment to cover the inset erosion and to abutt up to the neighbor's bulkhead. Otherwise, if there is heavy erosion you will need to fill wetlands then build a timber bulkhead. In Md that is not permitted, without a more serious wetland lic. and paying into a special fund. In any case do not allow the erosion to continue without armoring the slope.

[jwica]

Mikie,

a friend of mine had the same issue you are having with is property. he recently had a company come i and put out three jetties from his property. each jetty is aprox 30 ft apart and 30 feet out into the water. they trap the sand being pushed around by waves while breaking up the wave action before it hits his property. in the year he has had them, he has gained a tremendous amound of sand and expanded the size of his beach. In the same time, his neighbor has lost a good 4 ft, and several trees.

Quite a few property owners on the Wye River have these jetties.