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Hank Trangsrud <br />April 10, 2012 <br />Page 2 <br /> <br /> <br /> <br />problems with stability under the roadway (see Photo 1). The reach extends approximately 350’ <br />west of the church and 350’ east of the church. A majority of the eroding portion of the river bank is <br />now sloping at approximately 2h:1v (See Photos). <br /> <br />Alternative Solutions and Cost Estimates <br /> <br />Three options were investigated for feasibility. A small description of each option follows. <br /> <br />Option 1 – 78-foot Sheet Pile: Option 1 consists of driving approximately 78’ of sheet pile from Sta <br />0+00 to Sta 7+75. The option assumes continued scour up to the sheet pile wall and would not <br />protect the banks of the river from further erosion. This option would include minimal clearing of the <br />river banks. This option would also include guardrail along the entire project area to protect the <br />public from the sheet pile and drop off. Option 1 would cost approximately $1,693,700. The <br />breakdown of these prices can be seen in Attachment 1. <br /> <br />Option 2 – 30-foot Sheet Pile and Riprap: Option 2 consists of approximately 30’ of sheet pile <br />from Sta 0+00 to Sta 7+75, as well as some riprap to protect the bank from any further erosion. <br />This option would include some minor reshaping of the channel as well as clearing and grubbing. <br />This option also includes guardrail along the entire project area to protect the public from the drop- <br />off. Option 2 would cost approximately $846,400. The breakdown of these prices can be seen in <br />Attachment 1. <br /> <br />Option 3 – Riprap: Option 3 consists of clearing and grubbing, reshaping, and placing riprap along <br />the entire project area to protect the bank from further erosion. This option assumes a 2:1 slope on <br />the river bank pending geotechnical review. This option would not require guardrail as the riprap <br />would be placed outside the clear zone of the roadway. This option would require a clear zone at <br />least 12’ outside of the driving lane. Option 3 would cost approximately $339,000. The breakdown <br />of these prices can be seen in Attachment 1. <br /> <br />Study Limitations <br /> <br />This study was done at a feasibility level to minimize initial cost yet provide a reasonable opinion of <br />alternatives and costs. A geotechnical investigation was not done to keep study costs to a <br />minimum, but should be the next step if a project is developed. Sheet pile lengths, bank slopes and <br />riprap thickness were based on experience at similar sites and are subject to change. Costs for <br />engineering, construction administration and permitting were not detailed but are based on similar <br />jobs. <br /> <br /> <br />