Email Explaining How riprap works on Dredge Project

Rick

I'm sending you this email response to your concern regarding the visibility of the heavy riprap on the lakeward face of the stone berm that contains the dredge spoil. We looked this issue over, and we think that the riprap that was specified is in place, but much of it is currently partially obscured by smaller breaker run material placed on top of it, and is also obscured by snow and ice. There is what we considered:

1.      Tonnage of riprap placed: the design called for approximately 500 tons of heavy riprap to be placed, and the total from the truck weight tickets is approximately 650 tons. Granted, some of that material was placed on the original lakeshore protection, but the tonnage of stone placed on the lakeward face of the stone berm is greater than quantity specified in the construction plans.

2.      Photo log of berm construction: we've assembled photographs from February 11 through March 4, which show the placement and presence of the heavy riprap along the shoreline, and also the evident covering of that riprap with breaker run material to widen the path that was available for transit of the quad axle trucks that were delivering stone and dredge spoil. All I have with me tonight is a paper copy, but Danielle will forward you the photo log tomorrow morning.

3.      Photo log taken last Thursday, March 7: I had Badgerland Excavating expose the lakeward face of the berm at three locations with their backhoe. Photographs are attached. The photos showed that the heavy riprap is present, along with breaker run material placed over it.

I think that when the ice breaks up and after the first storm or two, the breaker run stone will settle into crevices within the heavy riprap, and the lakeward face of the berm will be well protected. We'll keep an eye on this, and I suggest we walk the berm sometime later this spring to confirm the stone placement.

We will place the supports for the carp gate tomorrow. When you get back from your trip, we can discuss the details of the carp gate placement and operation.