Killingworth City Zoning Code
ARTICLE XXXVI
Stormwater Management Plan
§ 500-222 Purpose and authority.
A.
Increased development without proper consideration of stormwater impacts can be a significant source of pollution to Long Island Sound, its tributaries, and other waters of valuable natural, economic, recreational, cultural and aesthetic resources. The protection and preservation of these waters is in the public interest and is essential to the health, welfare and safety of the citizens of the Town. It is, therefore, the purpose of this article to protect and preserve the waters within the Town of Killingworth from nonpoint sources of pollution through the proper management of stormwater flows and minimization of pollutants as defined by the "2004 Connecticut Stormwater Quality Manual" prepared by the Connecticut Department of Environmental Protection, as it may be amended (hereafter referred to as the CT Stormwater Quality Manual).
B.
The intent of the regulations is to set forth stormwater management plan requirements, including design practices and technical standards, to be incorporated in the planning, design, construction and maintenance of development proposals, redevelopment proposals and other activities that change the land's surface and alter hydrologic conditions resulting in pollution and adverse impacts to the surface water, groundwater and other natural resources of the Town of Killingworth.
§ 500-223 Applicability.
No person shall submit a special permit, subdivision, or resubdivision application without including a stormwater management plan that will control or manage runoff from the land, except as provided within this article. Furthermore, upon application for a certificate of zoning compliance the Commission may require that a Stormwater Management Plan be prepared, all or in part, as provided within this article when it has been determined that the development of the single-family dwelling may have an adverse impact on stormwater quality.
§ 500-224 Contents of stormwater management plan.
A.
Stormwater management plans shall include a narrative of the objectives of the plan, including the impacts resulting from the proposal or activity and a description of the practices, techniques, structures and facilities proposed to mitigate such impacts. The plan shall provide the following information and be prepared by an engineer licensed to practice in the State of Connecticut:
(1)
Soil characteristics based on site testing.
(2)
Location of the closest surface water bodies and wetlands to which drainage might be directed, and the depth to groundwater. Identification of Flood Hazard Boundaries as represented on Killingworth's Flood Insurance Rate Map (FIRM).
(3)
A description of design methodologies and computer models used, and hydrologic, hydraulic, sizing and water quality design computations for all practices and techniques, and structures and facilities. In general, this information should be submitted in accordance with the hydrologic and hydraulic design and analysis documentation requirements of the Connecticut Department of Transportation Drainage Manual. The design of all stormwater treatment practices shall be in accordance with the recommendations of the CT Stormwater Quality Manual.
(4)
Drawings including plan views, profiles, sections, and typical details of all stormwater management system components at adequate scale(s) and containing sufficient detail to clearly depict the intent of the design details of construction and/or installation, dimensions and materials including planting and landscape plans and details associated with stormwater management system components.
(5)
Structural design, geotechnical design and supporting information, as required by the Town Engineer for certain stormwater management system components, including storm sewers, channels, outlet protection measures, culverts, bridges, dams, spillways, outlet works, retention or detention measures, and other structures.
(6)
Location of all easements stating the specific responsibilities of the grantor and grantee as the access and maintenance of the stormwater system.
(7)
Proposed maintenance and operation manual or schedule for any best management practices (BMP) devices used to prevent pollution or treat stormwater.
B.
Upon written request of the applicant, the Commission may waive any part of this required information upon a finding that such information is not necessary to make a determination of the plan's compliance with the standards and criteria for decision.
§ 500-225 Standards and criteria for decision.
No stormwater management plan may be approved without a finding that the plan is consistent with the CT Stormwater Quality Manual and the following criteria:
A.
Design and planning for site development shall provide for minimal disturbance of predevelopment natural hydrologic conditions, and shall reproduce such conditions after completion of the proposed activity, to the maximum extent feasible as determined by the Town Engineer in accordance with the CT Stormwater Quality Manual.
B.
Pollutants shall be controlled at their source to the maximum extent feasible in order to contain and minimize contamination. Methods include but are not limited to sweeping of pavements, especially in the early spring, the use of sediment basins prior to infiltration and encouragement of sheet flow to filter strips. Snow removal should be placed on a site that will not cause pollution as defined in this section.
C.
All stormwater management systems shall be designed and maintained to manage site runoff in order to eliminate surface and groundwater pollution, prevent flooding and, where required, control peak discharges and provide pollution treatment.
D.
All stormwater management systems shall be designed to collect, retain and treat the first inch of rain on site, so as to trap floating material, oil and litter. On-site storage methods include but are not limited to landscaped depressions, grass swales, infiltration trenches and retention or detention basins.
E.
Stormwater runoff rates and volumes shall be controlled by slowing runoff velocities and infiltration. BMP methods for controlling runoff and infiltration shall be in accordance with the CT Stormwater Quality Manual. Stormwater management plans must demonstrate as close to a zero increase in runoff for the two-, ten-, twenty-five-, fifty-, and one-hundred-year design storms as compared to predevelopment conditions as is practicably possible based on site soil conditions.
F.
All stormwater treatment systems shall be employed where necessary to ensure that the average annual loadings of total suspended solids following the completion of the proposed activity at the site are no greater than such loadings prior to the proposed activity. Alternatively, stormwater treatment systems shall remove 80% of total suspended solids from the site on an average annual basis.