The Environmental Protection Agency (EPA) and city of Des Moines have announced the design firms that will work on a project to help the city build green infrastructure. Kansas City, Mo.-based BNIM Architects, which has a Des Moines office, and Omaha-based Vireo will work with the city and neighborhood representatives to focus on a streetscape plan for a one-mile section of Sixth Avenue. The firms will try to identify a variety of approaches to improve property development, make the corridor more transit-friendly for walking, biking and bus transportation, and developing bio-retention facilities to better control storm water runoff to help prevent flooding. The plan is intended to identify approaches that the city can later put to use.