Unless judged by the town to be exempt or granted a waiver, the following performance criteria shall be addressed for storm water management at all sites:
(A) (1) All site designs shall establish storm water management practices to control the peak flow rates of storm water discharge associated with specified design storms, and to reduce the generation of storm water.
(2) These practices should seek to utilize pervious areas for storm water treatment, and to infiltrate storm water runoff from driveways, sidewalks, rooftops, parking lots and landscaped areas, to the maximum extent practical to provide treatment for both water quality and quantity.
(B) All storm water runoff generated from new development shall not discharge untreated storm water directly into a jurisdictional wetland or local water body without adequate treatment.
(1) Where such discharges are proposed, the impact of the proposal on wetland functional values shall be assessed using a method acceptable to the town.
(2) In no case shall the impact on functional values be any less than allowed by the Army Corp of Engineers (ACE) or other agencies regulating wetlands in the state.
(C) (1) For new development, structural storm water treatment practices (STPs) shall be designed to remove 80% of the average annual post-development total suspended solids load (TSS).
(2) It is presumed that a STP complies with this performance standard if it is:
(a) Sized to capture the prescribed water quality volume (WQv);
(b) Designed according to the specific performance criteria outlined in the local storm water design manual;
(c) Constructed properly; and
(d) Maintained regularly.
(D) To protect stream channels from degradation, a specific channel protection criteria shall be provided as prescribed in the current storm water manual.
(E) Storm water discharges to critical areas with sensitive resources (i.e., cold water fisheries, shellfish beds, swimming beaches, recharge areas, water supply reservoirs) may be subject to additional performance criteria, or may need to utilize or restrict certain storm water management practices.
(F) (1) Certain industrial sites are required to prepare and implement a storm water pollution prevention plan, and shall file a notice of intent (NOI) under the provisions of the National Pollutant Discharge Elimination System (NPDES).
(2) The storm water pollution prevention plan requirement applies to both existing and new industrial sites.
(G) Storm water discharges from land uses or activities with higher potential pollutant loadings, known as “hotspots,” may require the use of specific structural STPs and pollution prevention practices.
(H) Prior to design, applicants are required to consult with the town to determine if they are subject to additional storm water design requirements.
(I) The calculations for determining peak flows, as found in the storm water design manual, shall be used for sizing all storm water management practices.
(Ord. 0504, passed 12-12-05)