Approximately 1,250 linear feet of masonry retaining walls along Minnehaha Creek, originally installed by WPA forces in 1937 within Minnehaha Falls Park, had deteriorated and become undermined. Blackstone Contractor’s was contracted by Aspen Construction in 2009, to perform the historic limestone masonry repair, including rebuilding and tuck-pointing different sections of limestone wall. Due to the wall’s historical significance, Blackstone’s masonry repair work had to comply with Federal and the Minnesota’s State Historic Preservation Office (SHPO) guidelines. This included salvaging and documenting placement of stone pieces and using restoration building material mixtures that comply with the historical time period of the original work. A portion of the work was completed during the winter during low creek water flows, therefore these areas were heated and covered to maintain optimal mortar curing temperatures (upper right). Blackstone also set new granite and limestone paving and seatwalls (upper left) to address the previously eroded streambank and provide a viewing area for park users along the creek.