Friday, July 5, 2019

Another Critical Improvement Project

Our drone's perspective of work in progress late last week, about five solid days into digging

For the second time in as many major projects, our excavating contractor proved us wrong. On both occasions he estimated the heavy lifting of their work would be completed in 7-10 days, on both occasions we were skeptical (at best), and on both occasions he got the job done -- both done well and on schedule. Seeing the long-reach excavator almost to the bay going into the holiday weekend has provided even more reason for celebration this 4th of July.

As with the last project (completed in 2016), this is a major victory for the broader project. And also as with the last time, the scope of the project involved the complete rehabilitation of ~3,000 linear feet of interior earthen berm (or "dike") on our West Marsh.

Makeshift repairs like this one were becoming more and more
frequent going into this spring; it will be nice to give the shovel
a rest and not have to go on daily patrols looking for leaks
This project quickly moved up the priority list as the water levels in the lake and bay continued to climb. We really started thinking about the need for this work in 2017. As repairs became more frequent in 2018, we started laying the groundwork from a permitting and funding perspective. But as water levels continued to press higher, it became evident that this really needed to be a 2019 project. It had reached emergency status.

We call this levee an "interior dike" (as opposed to a bay-front or lake-front "exterior dike") because under normal circumstances, it would be. But sustained historically high water levels in Sandusky Bay have backed water up on a neighboring property and in so doing exposed us to sustained water pressures that the original dike was never built to withstand. As a result, we leaked -- early and often through much of this spring. And the situation created a snowball effect that wasn't good for our near-term or long-term management goals.

Excessively high water on the neighbor's side of the dike meant one of two things. Either (1) we conducted business as usual on our side -- with lower water levels in the main West Marsh and sometimes daily breaches from head pressure differentials that were greater than the dike could withstand, or (2) we held our main West Marsh higher than we wanted (from a habitat development and broader earthen infrastructure perspective) to reduce the pressure and likelihood of regular leaks and blow-outs. Neither situation was ideal, but that's been the reality, really for the last couple growing seasons.

This image highlights the first couple days of
digging and the quality of the clay we found,
visible by the teeth marks of the excavator
seen in the lower-right (click to enlarge)
Fortunately for us, we had local knowledge that the clay we needed was available on site -- in fact, directly adjacent to the existing dike. Roy reminded me early on in this project that if there is high ground in a coastal marsh, there is usually deep water nearby. But fortunately for us, the "deep" water nearby (the channel from which the clay was excavated to build the original dike) wasn't too deep. And also fortunate for us, there was an ecological driver to dig the adjacent channel deeper.

The premise is this: by digging the channel deeper we accomplish two goals -- (1) we harvest the clay needed to rehabilitate the earthen berm over its original "footprint" in the marsh, and (2) we create deep-water habitat (8-10' deep) that will allow a broader diversity of fish species to survive weather extremes within the marsh . . . both extended heat spells in the summer and prolonged ice cover in the winter. This minimum depth tends to provide critical refuge from what would otherwise be fatally low dips in available oxygen. And it was this win-win that allowed us both to get the original permit from the US Army Corps of Engineers (USACE) and to begin the project before the typical July 1 start date. (The Corps and affiliated agencies typically restrict all "in-water" work through June to protect fish spawning, but in our particular case, the risk of waiting outweighed the risk of starting a couple weeks early, so we were granted a waiver.)

The first day of digging from another perspective (I'm standing on the far left of the new pile of clay for scale); we really
didn't know what the quality of the clay would look like until we started to dig -- we've been pleased from start to finish

This image depicts what ended up being the final day of excavation (before clay was "put up" onto the dike); with the muddy
bay water to the left and in the background, it serves as a stark contrast to the clear, stable water within the marsh (right)

Now that we are 95% finished with the excavating portion of the project, the risk of leaks or blow-outs is dramatically reduced. We will now wait for the excavated clay to de-water and dry, hopefully over the next couple/few months, and then the contractor will bring in a dozer to level the "crown" (top of the dike) and reshape the side slopes. By this time next year, we should be able to drive a pickup truck all the way around the West Marsh. This will be a first since we took possession of the property in 2015 and will probably afford the best access this site has seen since at least the 1980s.

One more fun perspective of this most recent work from the sky -- this one taken by ODNR
Division of Wildlife Private Lands biologist Mark Witt from the agency's helicopter;
two important notes: (1) Private Lands will once again be supporting this project financially --
which is immensely helpful, and (2) notice the water covering nearly all of the farm ground
on the very top of the page . . . absolutely amazing

The long-reach in action -- each bucket could be placed in 20-30 seconds