ETM was responsible for the design of widening approximately 12 miles of I-95 in Nassau County for the Florida Department of Transportation. The project added two lanes to the existing four-lane roadway and included both the design and permitting of roadway and drainage improvements. Stormwater treatment and attenuation were the largest challenges of the project, as approximately 50% of the alignment traversed wetland areas (including sensitive salt marshes).
Our innovative solution was to utilize compensatory treatment to minimize the required treatment volume thus reducing the number and size of required stormwater treatment facilities. ETM was the first firm to successfully negotiate compensatory treatment with the St. Johns River Water Management District. Once this approach was approved, ETM was able to provide swale treatment within the existing right-of- way, eliminating property acquisition costs and off-site wetland impacts. Along with stormwater management, ETM also provided roadway plans, signing and marking plans, maintenance of traffic plans and comprehensive landscape plans for this project.