(A) Unless judged by the city to be exempt or granted a waiver, the following performance criteria shall be addressed for stormwater management at all sites:
(1) All site designs shall establish stormwater management practices to control the peak flow rates of stormwater discharge associated with specified design storms and reduce the generation of stormwater. These practices should seek to utilize swales and natural depressions as site conditions allow, utilize pervious areas for stormwater treatment and to infiltrate stormwater runoff generated from driveways, sidewalks, rooftops, parking lots, and landscaped areas to the maximum extent practical to provide treatment for both water quality and quantity.
(2) All stormwater runoff generated from new development shall not discharge untreated stormwater directly into a jurisdictional wetland or local water body without adequate treatment. Where such discharges are proposed, the impact of the proposal on wetland functional values shall be assessed using a method acceptable to the city. In no case shall the impact on functional values be any less than allowed by the Army Corp of Engineers (ACE) or the appropriate state agency (e.g. IDEM, IDNR, etc.) responsible for natural resources.
(3) All sites shall store, infiltrate, filter, vegetate or any combination of these practices to reduce the impact of pollutants in storm water run-off on receiving waters. In addition to these practices, the following requirements shall be utilized:
(a) Infiltration practices will not be allowed in wellhead protection areas.
(b) Discharges from an MS4 area will not be allowed directly into sinkholes or fractured bedrock without treatment that results in the discharge meeting Indiana ground water quality standards as referenced in 327 IAC 2-11.
(c) Any stormwater practice that is a Class V injection well must ensure that the discharge from such practices meets Indiana ground water quality standards as referenced in 327 IAC 2-11.
(d) As site conditions allow, the rate at which water flows through the MS4 conveyances shall be regulated to reduce outfall scouring and stream bank erosion.
(e) As site conditions allow, a vegetated filter strip of appropriate width shall be maintained along unvegetated swales and ditches.
(f) New retail gasoline outlets, new municipal, state, federal, or institutional refueling areas, or outlets and refueling areas that replace their existing tank systems shall be required to design and install appropriate practices to reduce lead, copper, zinc, and polyaromatic hydrocarbons in stormwater run-off.
(4) To protect stream channels from degradation, channel protection shall be provided.
(5) Stormwater discharges to critical areas with sensitive resources (i.e., wellhead protection areas, cold water fisheries, shellfish beds, swimming beaches, recreational waters, recharge areas, water supply reservoirs) may be subject to additional performance criteria, or may need to utilize or restrict certain stormwater management practices.
(6) Certain industrial sites are required to prepare and implement a stormwater pollution prevention plan, and shall file a notice of intent (NOI) under the provisions of the National Pollutant Discharge Elimination System (NPDES) general permit, commonly referred to as Rule 6. The stormwater pollution prevention plan requirement applies to both existing and new industrial sites.
(7) Stormwater 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.
(B) Prior to design, applicants are required to consult with the city to determine if they are subject to additional stormwater design requirements. These additional requirements may include:
(1) Buffer strip and riparian zone preservation;
(2) Filter strip creation;
(3) Minimization of land disturbance and surface imperviousness;
(4) Minimization of directly connected impervious areas;
(5) Maximization of open space; or
(6) Directing the community's physical growth away from sensitive areas and toward areas that can support it without compromising water quality.
(C) The calculations for determining peak flows as found in the Stormwater Development Manual shall be used for sizing all stormwater management practices.
(Ord. 35-2004, passed 10-4-04)