From the regulations: (accessed August 17, 2015)
Redevelopment means replacement, rehabilitation, or expansion of existing structures, improve- ment of existing roads or reuse of degraded or previously developed areas for purposes of 310 CMR 10.58, governing work in the riverfront area. For purpose of the Stormwater Management Standards as provided in 310 CMR 10.05(6)(k) through (q), redevelopment is defined to include the following projects:
(a) maintenance and improvement of existing roadways including widening less than a single lane, adding shoulders, correcting substandard intersections, improving existing drainage systems and repaving;
(b) development, rehabilitation, expansion and phased projects on previously developed sites provided the redevelopment results in no net increase in impervious area; and
(c) remedial projects specifically designed to provide improved stormwater management such as projects to separate storm drains and sanitary sewers and stormwater retrofit projects.