Blue Earth County approves repair plans for County Ditch 25 after engineering report and cost estimate

The Blue Earth County Drainage Authority approved an engineer’s repair report and authorized engineers to prepare final plans and specifications for public bidding and construction of repairs to County Ditch 25 at a May 27 public hearing.

County Drainage Coordinator Craig Austin and ISG engineers presented the history, condition and proposed repairs for the County Ditch 25 watershed, described as about 1,768 acres in Decoria and McPherson townships. The engineer recommended primarily open-ditch cleaning, selective vegetation and tree removal, construction of alternative side inlets (ASIs) and a rock riffle sequence at the steep outlet to rebuild the channel bottom toward its legal grade. The total engineer estimate for the repairs was just over $330,000.

The report matters because the repairs are meant to restore constructed drainage capacity, reduce erosion that delivers sediment downstream and limit the frequency of future cleanings. Engineers described sections with up to two feet of accumulated sediment, side-slope sloughing at the outlet and several areas that require localized stabilization measures.

ISG engineer Chuck Bridal and colleague Jake Mueller walked the board through the watershed map, survey profile and photos. Bridal said the system was last cleaned countywide in 2008 and identified locations where culverts and crossings had been corrected then; he said most culverts remain adequate but sediment and vegetation have reduced the open-ditch capacity in many reaches. Mueller described the recommended measures: scooping sediment to reestablish legal grade where feasible, installing ASIs to collect runoff from shallow depressions before they cut into side slopes, and placing a rock riffle structure at the outlet to raise and centralize flow away from eroding banks.

The engineer provided a cost breakdown: approximately $184,000 for standard open-ditch cleaning on the main line; about $45,000 for Branch 1; $30,000 for Branch 2; roughly $56,000 for ASIs and alternative measures; total project estimate slightly above $330,000. ISG said it had referred concepts to the Blue Earth County Soil and Water Conservation District to explore partial funding, and estimated the ASIs and other BMPs could reduce soil delivery into the system by about 33 percent.

The hearing opened for public comment; no members of the public offered remarks. Commissioners moved to accept the jurisdictional documents and later moved to accept the engineer’s report and to order final plans and specifications for public bidding. The motions carried by voice vote.

The board’s action orders the engineer to finalize bid-ready plans and to return with the finance order required to proceed toward construction if funding and bids are favorable. The repair work timeline described by ISG could allow for bidding and construction later in the year if contractors are available and bids are within estimates.

The county will next incorporate the engineer’s final bid documents and finance order into the public-bid process; any funding partnerships with the SWCD were described as possible but not committed at the hearing.