(A) Storm water shall be conveyed through development in an adequately designed drainage system of natural drainage ways, grass swales, storm sewers, culverts, inlets and channels. Drainage systems shall be designed, constructed and maintained so as to provide natural infiltration, control flooding, extend the time of concentration of storm water runoff, and to control to the maximum extent practicable the impacts of development. Where the above conditions are met and where a development does not require the preparation of a Storm Water Management Plan, as provided in division (B) of this section, obtaining a town storm water permit is not required.
(B) Storm water management plans must be prepared for, and shall be approved by, the Storm Water Administrator pursuant to the application for a storm water permit for:
(1) All proposed developments that will exceed 20,000 square feet of cumulative impervious coverage. All the developments shall be required to construct a complete drainage system sufficient to mitigate the impacts of the design rainfall events identified in the Storm Water Technical Standards Manual and below;
(2) Any activity that disturbs land within a designated stream buffer area, except when the disturbance is designated as exempt or allowable in the Storm Water Technical Standards Manual;
(3) Any filling or excavation of a parcel in excess of 1,000 cubic feet of material, or any filling or excavation that would impact an adjoining parcel by resulting in the alternation of the drainage path, or the ponding of water, or a change in the storm water flow on the adjoining parcel; and
(4) Any activity or development that will ultimately result in the disturbance of a total area of one or more acres, except for the following:
(a) Activity on a bona fide farm, unless the activity is for non-farm purposes; or
(b) Activities on forestland for the production and harvesting of timber and timber products.
(C) Storm water management plans shall:
(1) Include drawings, maps, supporting calculations, specifications and summaries as outlined in the Storm Water Technical Standards Manual.
(2) Demonstrate through accepted engineering practices described in the Storm Water Technical Standards Manual the impacts of the proposed development. Impacts of the proposed developments may include:
(a) Effects on existing upstream and/or downstream drainage systems and property;
(b) Ability of the natural drainage way to handle additional storm water runoff;
(c) Water quality impacts on receiving waters; and
(d) Site-specific criteria.
(3) Demonstrate through accepted engineering practices described in the Storm Water Technical Standards Manual that storm water runoff is adequately conveyed through the development in a drainage system designed to meet the criteria described in the Storm Water Technical Standards Manual. The project shall control and treat the runoff from the first one inch of rain. Runoff volume drawdown time must be a minimum of 48 hours, but not more than 120 hours. High-density projects must discharge the storage volume at a rate equal to or less than the pre-development discharge rate for the one-year, 24- hour storm. All structural storm water treatment systems must be designed to achieve 85% average annual removal of total suspended solids; fecal coliform, and other pollutants to levels identified in the Storm Water Technical Standards Manual. Post development runoff rate shall not exceed pre-development runoff rate unless a maximum discharge rate has been adopted for the applicable drainage basin and the discharge does not exceed that rate. If a maximum discharge rate has not been adopted for the applicable drainage basin, post development discharge rate may not exceed pre-development discharge rate. Storm water volumes resulting from the proposed development shall be detained within the development and released at a rate no greater than existed prior to the development. Detention facilities shall be designed to maintain the pre-developed runoff rate from the one-year and ten-year design storm events, and other events as specifically required by the town’s Storm Water Technical Standards Manual.
(4) Demonstrate through accepted engineering practices described in the Storm Water Technical Standards Manual that storm water facilities control the impacts of the development to the maximum extend practicable and that those facilities are designed to meet the criteria described in the Storm Water Technical Standards Manual.
(5) All storm water management plans submitted for developments that incorporate structural storm water facilities or developments where the density exceeds 24% built-upon area must be designed to meet or exceed the criteria contained in 15A NCAC 2H .1008(c) and must be signed and sealed by a qualified professional.
(D) Storm water facilities inspection and maintenance requirements. A written inspection and maintenance agreement in a form acceptable to the Storm Water Administrator and executed by the applicant of the storm water permit and the owners of the facility, if different than the applicant, shall be provided prior to receiving a storm water permit. The agreement shall provide the following:
(1) Shall bind the parties thereto and all subsequent owners, successors and assigns;
(2) The required inspection maintenance and access of the facility as defined in the Storm Water Technical Standards Manual;
(3) If the town directs the correction, repair, replacement or maintenance of the facility in writing and the actions are not satisfactorily performed within a reasonable time (but not greater than 60 days), the town may, after reasonable notice, enter the land and perform all the necessary work and may assess the owner(s) of the facility with the cost of the work performed. The owner(s) served by the facility shall be jointly responsible to the town for the maintenance of the facility and liable for any costs incurred by the town pursuant to the agreement and all properties are jointly subject to the imposition of liens for the costs;
(4) The inspection and maintenance agreement shall be recorded in the Register of Deeds at the expense of the applicant; and
(5) Storm water facilities shall be included in an easement. The easement shall include the area of the facility, area of ponded water and enough area for access and maintenance. The easement shall be recorded in the Register of Deeds at the expense of the applicant.
(Ord. passed 7-15-2008)