Most of you are probably familiar with the stream that cuts through the back side of our property. You may have enjoyed crossing our footbridge, walking along the creek or garden trail or even tromping through the stream itself. With weather patterns changing and increasing in intensity, we’ve seen dramatic and rapid alterations to the stream bank, namely, erosion. Large volumes of water fill the stream at a quicker rate, and that powerful water flow carves away at every curve of the stream. While it’s not uncommon to see erosion and the lay of a stream change, it is uncommon to see it occurring so quickly. Needless to say, the relationship between the stream and its bank needs to be stabilized… and we can help with that! No speed dating, no blind dates, just good ‘ol bio-engineering to maintain our streambank.
You may be wondering why this is necessary since erosion is a natural process. Imagine driving on a curvy road. Driving at a lower speed makes you more likely to stay within the lines of the road, following the curve. However, at a faster speed you may veer a little outside the projected curve. This is similar to our stream. Because it’s filling with large volumes of water faster and more often, the speed of the flow increases; the stream veers outside the projected curve and carves away at the bank. Over time, this erosion creates significant undercutting of the bank, making it very dangerous to stand on the edge. Note: Always approach the edge of a stream with absolute caution for if erosion is occurring, your weight could cause the edge to collapse and you could get seriously hurt. In addition to creating a potentially dangerous situation, we’re losing property, soil and vegetation. When sediment washes away from a streambank, it can build downstream and cause issues like degrading aquatic habitats.
So how does one stabilize this erosive relationship between the stream and the bank? If you’re a home/property owner with a similar issue, you may want to pay close attention.
I used two bio-engineering methods:
- Revetment. Revetment is a structure, usually sloped and serving as a retaining wall, which works to buffer the energy from the stream while also collecting debris and sediment which builds up in front of and behind the structure. This year, we recycled our Christmas trees, and were graciously given “throwaways” from Big Run Evergreen, a Christmas tree farm located in Loudonville. The conifers were
overlapped and secured to one another, and the structure was then installed and anchored along the base of the eroding streambank. The trees/structure should be oriented so that the flow of the stream enters through the base of the tree first (the larger, spinier branches) and exits through the top/upper-most portion of the tree. There are other types of revetment that work well, but using what I had available to me was priority.
Make sure the trees are very well secured to one another by overlapping the top of one tree to the base of another. I found that thick wire worked best for this. I used 2-3 pieces in a twist tie fashion, which was effective because twisting the wire tightened and better secured the materials to one another. For my anchoring, I bent 2-foot rebar into hooks and ran cables from the revetment structure in the stream bed to the rebar hooks up on stable land. The hooks were then hammered into the ground, and I made sure to test their hold. Again, I used what was available to me (call it resourceful). If you’re attempting this, duckbill earth anchors would make all the difference. You could also reach out to your local NRCS office (Natural Resources Conservation Service) for advice and further assistance.
Okay, one 50-foot segment of streambank protected, another 50 feet downstream to go!
2. Fascine. I wanted to try my hand at making a fascine (rhymes with machine). There are a few different types. A brushwood fascine is a bundle of branches secured together and installed parallel to the flow of the stream at the base of the eroding bank. A live fascine is a bundle of cuttings typically consisting of willows, silky and red-osier dogwood, sycamore, elderberry and more, installed similarly. Both live and brushwood fascines will buffer the energy from the stream and collect debris, enabling sediment to build up in front, on top, and behind the structure. The benefits of a live fascine, however, is that you essentially have a “living-fence” which will root and begin to establish on-site, better stabilizing the area.
The first step of either type of fascine is to gather the woody vegetation and overlay the branches, then tie it all together securely. The size of branches for a brushwood fascine can range, but make sure it is feasible and manageable to bundle and firmly secure them together. Live fascine cuttings should be 3/8-1 in diameter and 3-5 ft in length (really depending on species/size availability and the length of fascine needed for your project). After you clip your cuttings, carefully remove any and all branches from them. If you are unable to install these live cuttings immediately, keep them from drying out. Consider taking a bucket of water with you for folding your cuttings until you are able to install.
Next, procure posts of some sort to anchor the fascine bundles in place. Most sources suggest rebar for this. A recently uprooted, dead pine tree worked well for me, providing multiple 4-5 ft trunk segments, which I fashioned into stakes/wedges. Additionally, I used the spiny branches of that pine for segments of my brushwood fascine. Regardless of what your posts are, make sure they are forcefully driven into the stream bed. Once you think the posts are well-installed, give it another beating for good measure. I drove my pine stakes into the stream bed with a sledgehammer, but rebar should go in more easily.
Posts can be driven into the center of your fascine, assuming the structure won’t be damaged. A wedge-style post will also better hold the structure down at the base of the bank. In addition, you can aim to drive the post through the string (or whatever material you used to bundle the fascine) which will further help secure the structure (again, assuming the structure won’t be damaged in the process). Alternatively, you could install the posts in either tight zig-zag pattern or straight line and weave your bundles in front of one post and behind the next, or install them in pairs, on on each side of the fascine.
Either way, make sure you run additional securities from the posts to the fascines. You never know how powerful the stream will get!
One other way to stabilize a streambank is live staking. Live stakes are individually installed behind your structures, or along a streambank, to take root. They are created with similar materials to live fascines, but should be a little bigger. A rule of thumb is to get cuttings that are roughly the diameter of your thumb (that rule should be easy to remember!). The length of these stakes can range from 2-4 ft. As with live fascines, remove all other branches from the cutting so that you have a decently straight stake. And if you cannot install these live stakes immediately, keep them from drying out by placing them in a container of water. Install your live stakes in the sediment behind your revetment or fascine or on the bank. Bank installation is best when the soil will remain consistently wet to moist, and obviously when the bank is truly an appropriate (secure) place. You may need to bore a pilot hole – slightly smaller than the diameter of the stake itself – as to not injure the live stake. Rebar can work well for this. Drive the stake at least 2/3 into the soil, leaving 1/3 exposed, and make sure it is perpendicular to the surface. Eventually, these live stakes will root and establish, leaving you with a stabilized and beautiful streambank!
This stabilization project has been a decent process for me. I began installing this structure toward the beginning of January. Within weeks of installing these structures, I’ve already begun to see debris collection and sediment buildup! I am very happy with how these structures turned out. An added bonus: those conifer revetments will serve as good bird habitats, too! Everyone’s a winner.
Until next time,