|Control of runoff from new and re-development projects, of significant size,
post-construction. Although post-construction control has been addressed in the past, Phase II regulations modify traditional runoff control by integrating
quantity and quality stormwater treatment practices.
Not only do the post-construction stormwater treatment practices (STP) have to manage the quantity of flow they must treat the runoff with a proven method of accomplishing A) a percent removal of pollutants of concern and B) attenuating or slowing the flow of runoff into Federal, State, & Local Waters. These types of practices help mitigate pollution into our lakes and streams
and prevent flooding and streambank erosion during more severe storm events.
Local Planning Boards should pay particularly close attention to this detail of the SWPPP filed by an applicant. In many cases, the post-construction treatment practices will be dedicated to the Municipality. The Municipality must then assume maintenance and repair responsibilities. If this is the case, Planning Boards should coordinate that portion of project review with their local Highway or Public Works Department. Practices adopted by the Municipality should be known performers and be easily assimilated into the Municipal MS4 Maintenance Program. It is also highly recommended that Municipalities establish a performance bond and detailed maintenance schedule for the practices to be installed. These should be agreed upon during project review and provided to the Municipality by the applicant. The performance bond, typically, would be for a five (5) year period. In cases where stormwater improvements are not to be dedicated, the Municipality should require a specific and detailed maintenance agreement with the party or parties to be responsible for such improvements once the project has been completed.
Whatever the case, post-construction controls have some very specific criteria to live up to, both aesthetically and environmentally. Planning Board Members and Planners & Engineers should pay close attention to this detail of any newly proposed project. Make sure that the Stormwater Treatment Practices (STPs) will live up to expectation because it is far more costly to residents and governments alike to correct a problem once it has already been built into a project.
Post-Construction Runoff Control, like many things, is more than the sum of its parts. Below are links and online resources to help anyone reviewing new or re-development projects: