§ 112-88. Stormwater performance criteria.

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 pervious areas for stormwater treatment and to infiltrate stormwater runoff 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 stormwater directly into a state water without adequate control of stormwater runoff. If 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 Corps of Engineers (ACE) or the state department of natural resources.

(3)

Annual groundwater recharge rates shall be maintained to the maximum extent practical, by promoting infiltration through the use of structural and non-structural methods where allowable.

(4)

For new development, stormwater treatment practices shall be designed to remove pollutants to levels prescribed in the current LDM. It is presumed that best management practices (BMP) comply 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 LDM;

c.

Constructed properly; and

d.

Maintained regularly.

(5)

To protect stream channels from degradation, a specific channel protection criteria shall be provided as prescribed in the current LDM.

(6)

Stormwater discharges to critical areas with sensitive resources (i.e., fisheries, shellfish beds, swimming beaches, recharge areas, etc.) may be subject to additional performance criteria, or may need to utilize or restrict certain stormwater management practices.

(7)

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. The stormwater pollution prevention plan requirement applies to both existing and new industrial sites.

(8)

Stormwater discharges from land uses or activities with higher potential pollutant loadings, known as "hotspots," may require the use of specific structural stormwater treatment practices (STPs) and pollution prevention practices.

(9)

Prior to design, applicants are encouraged to consult with the city to determine if they are subject to additional stormwater design requirements.

(10)

The calculations for determining peak flows as found in the LDM shall be used for sizing all stormwater management practice.

(Ord. No. 1812, § 4, 7-23-2018)