Mill Restoration

Wapsipinicon Mill, Independence, Iowa
Silos and Smokestacks National Heritage Area hired TDTW to assess flood-related damage to three Iowa Grist Mills. TDTW subsequently worked closely with the Buchanan County Historical Society, Owner of the Wapsipinicon Mill, and F.E.M.A.. This collaborative effort resulted in the successful granting of both remediation and mitigation funding from F.E.M.A. Over the years, the structural integrity of the meal floor system had been disrupted, allowing original historic timbers to float down the river during each flood of the Wapsipinicon River. TDTW was recently hired to remove all the non-historic fabric, and to re-establish the structural integrity of the original timber floor system. New timbers and flooring will be white oak, which was the original species used in the meal floor due to its rot resistance. The project is expected to be complete in the next couple months.

Though still standing proud, the Wapsipinicon Mill suffered severe damage to the meal floor where flour and other mill products were originally sacked for sale. The meal floor is located a few feet beneath the lowest course of windows. The water line from the July 2008 flooding still shows halfway up the limestone foundation.
 

A telling detail: This now rotted girt was once connected across the entire width of the mill. These Portland cement piers, poured in 1906, interrupted the continuous run of girts. Posts which once bore on these continuous girts now bear atop the tapered upper cement pier. Without the weight of the posts to hold down the floor girts, these shortened girts were held nothing except gravity, allowing the floor system to lift and wash downstream with each flood. The end of this particular girt is also rotted and will be replaced with sound timber. The floor system will be reconnected using period-appropriate metal bracketry, thereby re-establishing the structural matrix of the floor system and minimize future flood damage.

Damaged and moldy floor joists and flooring – all non-original – were removed in order to gain access to the remaining girt system and to replicate the original-flood resistant construction.

Joist and floor system sections were winched out along a 50’ ramp for further disassembly and disposal. Efficient material handling is essential to cost-effectiveness given limited access to the meal floor.