Motor Mill Bridge near Elkader, Iowa Part 2

Motor Mill Bridge in its original form. Photo provided by Hank Zaletel.

 

 

 

 

 

 

 

 

Part 2 of the series on Motor Mill Bridge near Elkader, Iowa is a long story about how the bridge, which was washed away by floods twice in 1991 and 2008, received new life as a replica that is now open to traffic. This time, it’s from the point of view of Jon deNeui, who is Vice President of the Motor Mill Foundation.  Here is the story behind the bridge:

Bridge restoration. Actually a replacement. I became involved with Motor in 2004 and as the Motor Mill interest group discussed how the planning should go I developed the idea that the repairs and restorations being discussed would cost in the 1 to 1.5 million dollars. The visitor rate on the open house weekends sounded like a variable 20 people. It seemed to me that the major factor limiting visitors was the approx. 8 miles of dusty gravel road. I guessed that that would filter a lot of visitors out. If that was a significant factor, how could we get more visitors to come. The county supervisors had indicated that major county spending at Motor was not going to happen so seal coating Grape and Galaxy roads was out of the question. I suspect that if we could increase the visitor vehicle numbers that the county would respond and upgrade the roads. Since the road across the river only counted 1.5 miles of gravel it became clear that developing access from that direction would be most effective. For this to work, crossing the river would be the key problem. Several options were discussed. These included modern bridges at the same or other locations as well as pedestrian bridges. The county would not consider any bridge construction investment leaving this up to the Motor Mill Foundation. With one span of the steel, pin connected Pratt through truss remaining I had the chance to get to know the structure and it’s design. Since the cost of a new bridge would be the responsibility of the Foundation I started looking at the least expensive way to get a bridge. Since there was no county owned land for parking on the other side of the river it became clear that the bridge would have to be “vehicle capable”. The County offered that if the bridge was “vehicle capable” they would include the bridge in the county secondary road system. This solved a major set of problems involving maintenance and operating costs. As I got to know the old bridge structure I began to see that building the same dimension bridge on the original masonry foundations was important. Then I could see that the 1899 span was made to be assembled in a low tech process that I thought could be in large part handled by volunteers. I found local masonry contractors and bridge erectors who would be willing to share the basic work with volunteers. We had a local steel fabricator who could cut the parts needed. Local truckers would help with material transportation. I knew that the heavy workl would need to be done by experienced professionals, no problem there. At that point I was scheming on how I could get a steel supplier to partner on the steel materials.

The problem would be to convince my friends that the kind of bridge and location of it could only be reached by one path. by 2006 I had a lot of answers and had put some estimated costs built from actual proposals from suppliers, fabricators and contractors. In 2007 and early 2008 the Motor Mill Foundation board came to agree with the proposal to construct a replica of the old steel truss bridge with a new one. The county and state historical folks agreed to the new replica with a proviso that the remaining span would be kept as an exhibit. As time passed the costs went up and finding a cooperative engineer was a problem.
In June of 2008 the flooding Turkey River took out the remaining span. This set up a series of events that led to a new “old” bridge. FEMA arrived in the late fall asking why this “Historical Site” hadn’t asked for flood repair dollars. I had thought that the flood damage was minimal to our buldings and since the remaining span of the bridge was borderline junk before the flood, there was little to ask for. It became clear that FEMA was interested in our historical site and actually was interested in replacing the single span lost in 2008. Once the agency’s willingness to support the replacement of half a bridge was confirmed, Tim Englehart obtained a REAP grant and the project was nearly funded. It seems that the years of discussions and exploring a new bridge and with all involved persons agreeing on what should be done, made our bridge nearly a shovel ready project. That didn’t hurt us either.

General History: Motor Mill was a dream project that developer/mill builder John Thompson wanted to build. He bought the property nearly twenty years before the Motor Mill was built. Both the Mill Complex and the bridge were begun in 1867 and 1868. The first bridge structure was a three span wood truss bridge. Part of the limestone for the bridge abutments and piers was quarried from the hole needed for the basement of the mill. The lime kiln built to produce lime for the Mill buildings also provided lime for the bridge masonry. Sand for the whole project was taken from the riverbed. The mill was finished late in 1869 with a test run between Christmas and New Years. The mill went into full production in January 1870. Wheat was purchased locally and hauled to the mill in wagons. A narrow gauge railway was attempted but after being washed out was abandoned. The mill continued to produce flour from local and imported wheat until it was closed in about 1885. Thompson and partner Crosby bought the third partner’s share and then petitioned the court to dissolve the remaining partnership. Lack of adequate transportation of wheat coming in and flour being shipped out was one serious factor limiting the success of the mill. Another factor was repeated population explosions of Cinch Bugs. These bugs decimated the local wheat growing and the farmers had to find a crop that could generate cash flow for their needs. The mill was sold to local farmers and was used for private farm related purposes. In 1905 the Klink family bought the mill and related property. They continued to own this property until 1983 when Clayton County bought the historic site for future use as a historical site.

Reconstruction: In 2004 and 2005 I became fixated on the old bridge span and spent a lot of time looking and figuring out the structure. I made Auto Cad drawings representing the existing structure. These drawings can be seen if you want. The first thing I discovered was that the spans had been prefabricated to be assembled in the field. All the fabrication shop assemblies were hot riveted together. All the Field connections were bolted. The primary erection was a combination of 2? pins and 1/2? and 5/8? bolts. This was when I began to think that the spans were relatively simple and the parts could be made and assembled locally by volunteers and cooperating businesses. The final erection would be done by a bridge contractor. After the real money became available the idea of volunteers doing the work was replaced by a professional team of engineers and contractors. When this changeover happened the concept of a nearly complete replica of the original steel spans was a major factor agreed to by nearly all involved. The Bridge components were fabricated near ST Paul MN. The bridge was erected by Minowa Bridge Construction from Harmony MN. The steel was delivered in late Sept. 2012. Masons began working on the foundations in early October 2012. Assemblly of the spans began later in October and by the middle of November the spans were set into place. The work was finished and a ribbon cutting opened the bridge to traffic on December 8, 2012.

Historic status: The project had been discussed with the Iowa State Historical people in Des Moines from the early days in 2004. Clayton County Historical Preservation, County Supervisors and the National Park people were contacted and many discussions brought together the concerns both concurrent and conflicting. The Historic Register accepted the proposed bridge replacement with the afore mentioned proviso that the remaining span be converted to an exhibit that people could come and put their hands on. The proviso was dropped when the poor old span was destroyed. However they had seen my cad drawings of the old bridge enough times that we were in good position to assure them what we would be putting back. We never lost the historical site status.

Funding began with a FEMA grant followed by a REAP grant and supported by several smaller grants and gifts. We have set out to obtain enough funds to cover some costs which couldn’t be coverd by the grants and gifts.

The new bridge is not a full replica of the old spans. The engineers had some serious reluctance to repeat the Pinned Connections. The peculiarity of the pin connected Pratt truss was anchored in an engineering concept called “Critical Fractre”. This means that within the structure of the span if any part fails the whole thing falls down. Since the bridge advocates were firmly based in the need of a visual replica of the old bridge the engineers were convinced to use an overall replication of the old bridge with modern connection systems and additional strength where potential fractures could happen. They also substituted welded joins for riveted connections. We/I didn’t get everything we wanted and the engineers didn’t get everything they wanted. But we agreed that the structure would be a good strong one. One benefit of our situation was that the IaDOT had no jurisdiction and was consulted for several standards such as guard rails etc. IaDOT review and oversight was not something that slowed our progress. For most visitors the bridge looks just like the old one. I’m working on getting accustomed to the variations from the original. The bridge is a good strong and serviceable structure.

Public Response to the bridge replica/ project: In the early stages the public response was, “I’ll believe it when I see it.” In the mid stages their response was, “It’ll never get off the ground.” When the funding was obtained and we moved into the building stage the comments were, more like, “You can’t get it done for that little cost.” Actually their response was hopeful and wistful about their memories of the old bridge. As we moved into the later stages more and more of the general public as well as public figures became more supportive and encouraging. They just had to get past their doubt. Now the public has visited and is happy with the results. They can’t believe that the 72,000 pound design strength was accomplished for the low cost. But folks are talking to all of us about how great the finished bridge is for the county.

To see the interview with Tim Engelhardt, please click on the link here.

The replica version of Motor Mill Bridge. Can you see the differences between the one photographed by J.R. Manning and the original provided by Hank Zaletel?

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