(CS3.5) The Four Mills Barn and the Rising Water

Changes in the Wissahickon Creek near Philadelphia, Pa, over the last 150 years has affected the flood plain and has forced change to everything in its path. The Four Mills Barn, constructed in the late 19th century adjacent to the Creek, was one of those things now in its way. A recent rehabilitation campaign was completed to adapt the Barn to the new Wissahickon.
Founded in 1955, Wissahickon Trails is a non-profit dedicated to land and water conservation around the Wissahickon Creek. With its mission to “inspire and engage diverse communities of people to protect, steward, and enjoy the land and waterways of the Wissahickon Valley”, the Barn has been the perfect location for the organization’s headquarters. Designed by Horace Trumbauer in 1891, the building was a modern version of a bank barn with masonry on the ground level and a wood frame above. It was first rehabilitated, and became the organization’s headquarters, in the 1980s.
Wissahickon Trails operated on the first floor of the barn for more than 40 years before being forced to reconsider the way it used the building. After a recent reevaluation of the FEMA floodplain map, the Barn has been deemed to be within the floodplain. The creek now regularly breaches its banks. In 2020, Tropical Storm Isaias pushed the creek waters into the building’s first floor to a depth of two feet, causing significant damage, and forcing the organization to demolish interior renovations that had been in place since the 1980s. Wissahickon Trails had to adapt or abandon the building.
With storms becoming more frequent and more intense, Wissahickon Trails knew Isaias wasn’t a once-in-a- lifetime event but it still wanted use of the first floor. With buy-in from the Township and the client, the design team of Daedalus Design Building and Kate Cowing Architect, LLC used “wet-floodproofing” techniques to rehabilitate the building. This is a FEMA-approved system that acknowledges that the first floor will continue to flood. It doesn’t attempt to block the creek’s floodwater but rather allows it to enter. It requires an acceptance by the building’s caretakers that work will be necessary after a storm. Although perhaps not for everyone, this system, in the eyes of this environmental group, is a more realistic method of dealing with flooding. It doesn’t constantly battle against nature but instead works with what it brings.
This restoration expanded the headquarters for Wissahickon Trails and has made the building itself a tool to teach about changes in climate. It has allowed this historic barn to remain in use despite environmental changes that may have otherwise rendered it obsolete.