2021 Hydraulic Dredging & Silt Basin
BOTTOM LINE UP FRONT
Over the years, silt and sediment has built up on the lakebed which reduces the depth of the waterways making boating more difficult, spurs algae growth and aquatic weed infestations, and leads to poor conditions for fish. Without thoughtful action now, our beloved Lost Lake will eventually become Lost Swamp.
WORK TO DATE
In 2019, The RCD Board engaged The Mapping Network to create a “bathymetric survey” (equivalent to mapping the topography on land). With this survey, we were able to quantify in detail the problems that homeowners have experienced over the years. Next, the RCD elected to work with JadEco Lake and Natural Resources to guide the development of an action plan to restore and improve the viability of Lost Lake for years to come. The firm has assisted in our lake and watershed management projects since 2006.
While it is counterintuitive for most of us, the first stage of the planning involved land. Regardless of the method, the material from the lake has to be transported, dewatered, and temporarily stored before eventual disposal. Working with Wendler Engineering, we have identified a 22-acre RCD site for a sloped basin to store the removed silt and sediment for further processing. Temporary piping connecting the lake and the basin will be installed, at times, for maintaining Lost Lake in the future. By knowing the capacity of the basin, we now understand how many cubic yards of material can be removed in each phase of the project. Since dredging contractors are usually paid based on cubic yards removed, this information is important in budgeting our share of the investment in maintaining a healthy lake and enhancing the value of our homes. On July 16, 2020, the RCD board approved an ordinance to submit the proposition of issuing bonds to cover the cost of this critically-important project (not to exceed $948,000). On November 3, 2020, homeowners within the Lost Nation – New Landing River Conservancy District voted 388 yes and 98 no so that the proposition passed.
The RCD engaged Bernardi Securities to issue bonds and to work with individual homeowners to understand the possible impact of the project on their individual property taxes. The bonds were then secured in March 2021 and the board accepted bids to build the silt basin for the bid opening at their May 13th open meeting. The RCD received four bids and awarded the bid to Fischer Excavating at the June 17th open board meeting.
In August 2021, Fischer Excavating broke ground on the building of the silt basin.
To manage costs and protect the lake’s ecosystem, the RCD and its consulting team recommend a “spot” dredging program using a hydraulic system. Spot dredging can be beneficial in improving boat and shoreline access, clearing clogged channels and bays, creating hollows for cool water fishes in the summer, and deeper areas for fish in the winter, and forming boat and fish "cruising lanes" through aquatic plant beds. The dredging machinery is incorporated onto a floating hull. A cutter with steel blades dislodges the sediments, and a centrifugal pump "sucks up" the muck. This sediment/water mix (called a slurry) is piped to the disposal basin on land where the water is drained off and the sediments are left to dry.
Click the above graphic to enlarge it.