Today , from its position seven feet upstream of the historic Lanesboro Dam , the cellular dam reduces the force exerted by the flowing water of the Root River . So even if the historic limestone dam were to collapse , the cellular dam immediately behind it would be there to contain the river , thereby mitigating the risk of a catastrophic flood .
And because the cellular dam is not quite as high as the limestone dam , a small amount of river water flows over the top making it virtually invisible . As a result , the second dam does not detract from the historic dam ’ s visual appeal .
Other Work
Some repairs also were made to the limestone dam itself . But they were limited to those sections that had been
altered sometime after the 1800s . For example , a concrete cap installed atop the stone arch dam in the late 1980s was repaired to enhance the overall stability of the dam .
The limestone dam also had several leaks that needed attention . In making those repairs , SHPO guidelines prohibited the use of materials that weren ’ t available to craftsmen during the 1800s , again for fear they would detract from the historic look of the downstream face of the dam . But to seal the leaks workers were allowed to apply “ shotcrete ,” a form of sprayed concrete , to the upstream side of the dam , which is not easily visible .
Also receiving attention as part of the Lanesboro Dam restoration project was a small hydroelectric plant on the west side of the dam and a canal that carries river water to the plant to power its turbines .
The hydro plant , which has been owned and operated by the City of Lanesboro since 1903 , produces 250kw of electricity .
While that doesn ’ t come close to meeting all of Lanesboro ’ s power needs , “ everything that we can generate helps offset expenses to our community ,” Peterson said .
Plenty of Credit To Go Around
Goodwin is proud of his innovative approach to the Lanesboro Dam challenge . “ I think we had a really good design , a design that was unique ,” he
Continued on page 21 www . AyresAssociates . com 19