To: Lake Viking Board of Directors
From: Shawn Hepinstall,  Dredge Committee
Date: 8/26/2020
Re: Dredge Update

Below is a silt basin planning update and information on dredging operations. Our members approved the funding to build a new basin and a lot of planning has been taking place. We are on track for plan proposals to the board for approval in fall, construction bids in winter 2021 for construction summer 2021. Separately, we are also conducting dredging work in other areas based on our 2020 budget and implementing a proactive approach installing weirs, dipping and stabilizing banks.

South End Silt Basin: Earlier this summer we drained a lot of the basin, cleared vegetation and removed much of the silt Island in the middle of the basin. This gave us better a view of the scope regarding what needs to be moved and helps our engineer in the design of the new basin. Boring and Core Samples  Soil analysis and borings were done by Kruger Technologies in nine spots. Overall, our site soil tested very well and is acceptable for berm construction. We did encounter bedrock in several locations but nothing of a major concern.

Silt Analysis: Composition of our silt was tested and results came back as the finest silt that Bob Hayes or  Steve Warger  (Warger Engineering)  has ever seen. It’s 75% fine silt and 25% clay. It’s
almost a powder as it is carried in the water. It is very hard to contain or stop. It requires settling which will factor into the design or our new basin.

Warger Engineering Plan: Steve and Bob have been working on the analysis and several preliminary ideas were shared with the committee in June. Steve said he have will three preliminary plans ready for committee review the week of Aug. 17.

Garney Area: Normal 2020 dredging operations have been taking place in the Garney area. This activity was part of the 2020 dredge budget to be proactive in silt removal. We have constructed a new silt basin in the Garney Area and will incorporate a “prototype” dewatering system into the new basin. The new basin will hold and filter silt, then drain to a second lower pond for more settling, then return water to the lake. If this process works as designed, it will capture silt and the basin will dry out so we can maintain it in the future. This is a smaller scale of what we hope to build into the new basin on the south end. Weather permitting this should be completed next week or the week after. 

There is/was no place to pump the silt until the new basin was completed so we chose not to put the dredge in until the basin was ready. We will dredge in the danger area in the middle of the lake
first and then move to Garney and dredge, testing the basin and dewatering system.

Stream Bank Stabilization and Dipping: This fall we will continue dipping and stream bank stabilization to slow the silt coming into the lake.

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