M3 Engineering performed an alternatives analysis and design to alleviate flooding of residential and apartment structures along several miles of Cole Creek Cole in the City of St. Charles, MO. Residents along Cole Creek have suffered from flooding for several years, so the City committed to implementing a multifaceted project to address the situation. Using XP-SWMM to model the open and enclosed storm systems, M3 determined that the root cause of the flooding includes undersized bridges, a lack of stream capacity and houses that were simply built within the floodplain.

The preferred flood reduction solution included: replacing a Norfolk Southern Bridge; replacing two vehicular bridges; converting a sludge basin to a storage basin; widening Cole Creek; floodproofing at-risk homes; and building regional detention facilities.

In addition to managing the project, M3’s responsibilities included the hydraulic design for all improvements, preparation of construction documents, construction cost estimating, securing a USACE 404 permit, design of streambank improvements and arranging public information events to notify residents and gather their input.