The anatomy of a log v-weir pool with engineered undercut stream banks.
This photograph tells a story of construction, on a particular log v-weir that I constructed, along with the help of my crew, on a small stream in the north country. The pool in the photo is only just been started in construction, but the on-hand materials tell part of the story for me.
The rail coming out from the end of the wings of the v structure, are part of the foundation for the engineered undercut stream bank. This particular-design is used when you need to add cover habitat to a pool, to get the full benefit of the structure’s purpose, in providing cover habitat and wintering habitat for juvenile trout and adults, whatever moves in when constructed.
Of-course, we all know that the more dominate adults of some species of trout are territorial, on the other hand, the brook trout seems to meld together well in tight crowded places, for long durations during the winter months, under the cover of ice.
The rail is also mounted to 6 posts that are driven 3 to 4 feet into the stream bed, even if it is gravely, you can pilot a hold with a steel rod and then follow with the wood post. As you can see from the top of the posts, even with a post hold driver that is 6 inches in diameter, the tops of the posts still split on the fresh wood. You don’t have to worry about your wood drying out, so fresh cut is good.
When submerged, wood goes into a state of preservation, so the roots of growing willows and trees will absorb the engineered undercut banks, over time. This leaves just the woven roots to hold the undercut in place, and they will. A slight bench is created when excavating the pool around the outside edges, so the cover post can rest on the soil foundation, which is created.
The ends of the cover posts, which are driven horizontally into the stream bank on both sides, also have spruce boughs attached to the ends, for added mesh to help hold any soil and sod placed on the top of it during construction. Because of the tight banks on the creek, with high slopes, a special bit of engineering goes into the plan for a stable, long lasting stream bank, which looks natural.
When all-of the platform created by the horizontally driven posts is complete, a few layers of burlap or jute is placed over the platform and then soil and sod can be added back on the top. The excavator stored the cap of sod for the reclamation of the site, and even a few tall willows were stored and then placed back to where they were situated before the new culvert was installed on the road crossing.
All of this work happened while logging trucks roared by, because the road had been opened back up for business, and this left our crew to work in the dusting ditch area for the grand final of the enhancement program. However, the dust and grit in the teeth was all worth the effort, because the finished product pasted with flying colors!
