The existing SR 0722 Bridge and dam over Lititz Run was integral in the operations of the nearby Oregon Mill, which is listed on the National Register of Historic Places. Structurally deficient and functionally obsolete, however, the existing SR 0722 Bridge needed to accommodate modern-day traffic demands. The backwater condition resulting from the dam served as specialized habitat for the State-endangered black-crowned night heron. The need to preserve this backwater habitat while removing the dam to accommodate fish migration was an added challenge. The Pennsylvania Department of Transportation wanted the replacement structure to preserve the historic setting of Oregon Mill yet desired a consultant who could also address the environmental constraints and challenges this bridge replacement project posed.
RETTEW designed a single-span prestressed-concrete bridge with architectural surface treatments on the parapets, which mimic the stone on the historic mill. To preserve the black-crowned night heron habitat and accommodate fish migration, we removed the dam and installed in-stream grade control structures. The grade controls maintain water levels for the adjacent heron rookery and are still passable by fish. Additionally, the wider two-lane structure accommodates traffic demands while preserving the historic setting of Oregon Mill.