Maintaining A Historic Structure in Water Works Park

Submitted by Doug Verdier

Earlier this month (June 9) West River Parkway was temporarily closed to vehicular traffic between 4th Avenue N and Portland Avenue for a couple of hours. The closure was necessary to allow a repair along the foundation of the former Columbia Flour Mill structure near General Mills Plaza fire pits in Water Works Park.

Built in 1882, the Columbia Flour Mill was originally six stories high with a basement. It was located between the Bassett Sawmill buildings (now the site of the Owamni restaurant and park pavilion) and the Occidental Feed Mill. The Columbia Flour Mill was destroyed by a fire and collapsed in 1941, and the area was used as a dump for many years. In more recent times, the area was filled and used as a parking lot for several years until the Minneapolis Park and Recreation Board (MPRB) together with the Minneapolis Parks Foundation, began work to create a new Downtown park, now known as Water Works Park.

During excavation in preparation for work on the new park, a 55-foot-long rail car scale was among the artifacts uncovered in the vicinity of the Columbia Mill ruins. Other artifacts and machinery from the milling era were also found in the basement of the Columbia site after the fill material was removed from inside the remaining outer walls of the mill building. These were examined by archeologists before the structure was reinforced and filled again to its current level. This area is now an outdoor terrace and lawn used for events and outdoor seating for Owamni patrons.

The repairs that were made recently were likely the result of some settling of the fill material that was placed inside the reinforced walls of the former Columbia Mill structure. Some shifting of fill likely occurred around machinery and other items that were covered with a geotextile cell fabric material that is commonly used for soil stabilization in construction projects.

Two blue Cemstone trucks delivered and pumped the fill material to the repair site.

Workers inserted a hose from a Cemstone cement truck along the foundation of the former Columbia Flour Mill building to pump “flowable fill” beneath the structure. Workers closely monitored the fill while it was being pumped.

According to Jon Duesman, Construction Project Manager for the MPRB, the repairs involved pumping what is called flowable fill beneath the corner of the structure to fill the gap caused by the settling. Flowable fill consists of water, fly ash, sand and cement, and was delivered to the site by Cemstone. The liquid mixture will find any gap and fill it and it is self-leveling. The process took less than an hour to complete and used only a few cubic yards of the flowable fill material.

There will be some finishing along the top surface of the area where the fill was inserted, but that is not a major project, according to Mr. Duesman. MPRB employees will complete the job.