CEI was contracted by the Town of Lexington to provide engineering and permitting services to design two separate stream crossing culvert replacements. The first crossing consisted of an undersized culvert made up of three different pipe materials and dimensions which transitioned at in-line catch basins on Revere Street. The second crossing was a three-sided granite stone box culvert which originally crossed beneath the old railroad line which is now the Minuteman Bikeway. The pre-construction culvert at Revere Street was more than 50% blocked with organic debris and sediment at the inlet end, coupled with in-line catch basins providing no pre-treatment to stormwater runoff and material and dimensional changes causing hydraulic restrictions. The culvert at the Bikeway was causing section loss beneath the Bikeway pavement due to a broken granite top slab within the culvert, there was also extensive scour beneath the culvert extension walls in the vicinity of a nearby drainage outfall pipe.