Post-Construction Stormwater Control
Sec. 6.22. Post-Construction Stormwater Control.
Section 6.22.1 Purpose (a) Unmitigated storm water from areas altered by development may pose public health and safety threats. Potential contaminants in storm water runoff may include suspended solids, nitrogen, phosphorus, hydrocarbons, heavy metals, pathogenic organisms (bacteria and viruses), and road salts.
(b) This article establishes the administrative mechanisms necessary for the town to ensure proper storm water management of runoff from new development and redevelopment projects. The ordinance from which this article is derived is written to work in conjunction with the Rhode Island Department of Environmental Management's General Permit, Rhode Island Pollutant Discharge Elimination System (RIPDES) Storm Water Discharge from Small Municipal Separate Storm Sewer Systems and from Industrial Activity at Eligible Facilities Operated by Regulated Small MS4s.
(c) This ordinance is responsive to Rhode Island General Law 45-61.2-1 Findings. – (a)
The general assembly hereby recognizes and declares that: 6-56 (1) Stormwater, when not properly controlled and treated, causes pollution of the waters of the state, threatens public health, and damages property. Stormwater carries pollutants into rivers, streams, ponds, coves, drinking water aquifers and Narragansett Bay;
(2) Stormwater reaches the state's waters by streets, roads, lawns and other means. As a result, public use of the state's natural resources for drinking water, swimming, fishing, shellfishing and other forms of recreation is limited and in some cases prohibited;
(3) Development often results in increased stormwater runoff by increasing the size and number of paved and other impervious surfaces within the state, and decreasing the amount of natural surface areas that naturally control stormwater runoff through natural filtration and groundwater recharge systems;
(4) Development in the Town of North Smithfield will strive to maintain predevelopment groundwater recharge and infiltration on site to the maximum extent practicable;
(5) Demonstrate that post-construction stormwater runoff is controlled, and that postdevelopment peak discharge rates do not exceed pre-development peak discharge rates; and
(6) Use low impact-design techniques as the primary method of stormwater control to the maximum extent practicable. Section 6.22.2 Definitions.
For the purposes of this section, the following words and terms shall have the meanings respectively ascribed, unless the context otherwise requires:
Applicant means any person proposing a development project in accordance with this article. The applicant must be the person who holds a valid purchase and sales agreement for the real property associated with said development project.
Authorized enforcement agent means the building official, zoning officer, or other town official authorized to enforce standards in accordance with this article.
Best Management Practice (BMP) means any structural and nonstructural means applied to a development project with the intent of controlling storm water flow and quality. Best management practices include, but are not necessarily limited to, means of storm water management described in with the Rhode Island Stormwater Design and Installation Standard Manual (RISDISM), as amended. Use and acceptability of best management practices is at the discretion of the town.
Development project means any construction, reconstruction, demolition, or removal of structures, roadways, parking, or other paved areas, utilities, or other similar facilities, including any action requiring a building permit by the town. 6-57 Low-impact development means a best management practice intended to maintain or replicate predevelopment hydrology through the use of site planning, source control, and small-scale structures integrated throughout the site to prevent, infiltrate and manage storm water as close to its source as possible. Low-impact development practices include, but are not necessarily limited to, those described in the state storm water design and installation standards manual, as amended. use and acceptability of low-impact development practices is at the discretion of the town.
Owner or operator means any person who holds legal title to any real property, development project or structural best management practice; or has possession or control of any real property, development project or structural best management practice through any agent, executor, administrator, trustee or guardian of the estate of a holder of a legal title.
Person shall include an individual, trust, firm, joint stock company, corporation (including a quasi-governmental corporation), partnership, association, syndicate, municipality, municipal or state agency, fire district, club, non-profit agency or any subdivision, commission, department, bureau, agency or department of state or federal government (including any quasi-governmental corporation) or of any interstate body.
Storm water management plan means a plan that prescribes site design elements and
| construction practices, that if employed, | improves area water quality by preventing |
| harmful pollutants from being carried by | stormwater runoff into local water bodies. |
Storm water means the surface discharge of water associated with a precipitation event or snowmelt.
Section 6.22.3 Applicability This article shall apply to all subdivision and land development applications that disturb one acre or more of land. No person shall engage in development projects without receiving approval from the building official and or Planning Board unless specifically exempted by Section 6.22.4. Section 6.22.4 Exemptions The following development projects do not require written approval pursuant to this article:
(1) Construction, alteration, or use of any additions to existing single-family or twofamily homes or related structures, when determined by the building official to be insignificant, and such construction, alteration and use does not exceed 1 acre of land, does not occur within 200 feet of any watercourse or coastal feature, and the slopes at the site of land disturbance do not exceed ten percent.
(2) Accepted agricultural management practices such as seasonal tilling and harvest activities associated with property utilized for private or commercial agricultural or silvicultural purposes.
(3) An excavation which exhibits all of the following characteristics: 6-58
a. Is less than four feet in vertical depth at its deepest point as measured from the average elevation of the natural ground surface.
b. Does not result in a total displacement of more than 50 cubic yards of material on any lot, land, parcel or subdivision.
c. Has no slopes steeper than ten feet vertical in 100 feet horizontal (ten percent).
d. Has all disturbed surface areas promptly and effectively protected to prevent soil erosion and sedimentation from occurring including seeding or sodding, and provided that all disturbed surface areas which will be exposed for a period of time in excess of 30 days shall be covered with a suitable temporary protective ground cover until permanent ground cover is in place.
(4) Grading, as a maintenance measure, or for landscaping purposes on existing developed land parcels or lots, provided that all of the following conditions are met:
a. The aggregate area of activity does not exceed 1 acre.
b. All bare surface area is promptly seeded, sodded, or otherwise effectively protected from erosive actions.
(5) Grading, filling, removal or excavation activities and operations undertaken by the town under the direction and supervision of the Director of Public Works for work on streets, roads or rights-of-way dedicated to public use; provided, however, that adequate and acceptable erosion and sediment controls are incorporated in engineering plans and specifications and employed. Appropriate controls shall apply during construction as well as after the completion of such activities.
(6) Use of a home garden in association with residential use. Section 6.22.5 Variance The building official reviewing an application under this article may:
(1) Vary requirements of this article when strict implementation of the requirements will create an unnecessary hardship or are not feasible.
(2) Allow use of an innovative management practice where strict adherence to existing criteria would be costly or of negligible environmental benefit.
(3) Allow use of an innovative management practice where the innovative practice is expected to have an environmental benefit, which cannot be practicably realized using standardized management practices. Section 6.22.6 Submissions and Approvals (a) In accordance with this article, all persons must obtain approval from the building official prior to engaging in any development project, unless exempted by section 6.22.4. To obtain approval applicants must demonstrate compliance with all policy, standards and requirements of this article to the satisfaction of the building official. 6-59 Applicants may demonstrate compliance via submission of materials and documentation including but not limited to a storm water management plan, site plan and maintenance agreement in accordance with this article. Plans will be reviewed in conjunction with site plan reviewed by the building official.
(b) Pre-application meetings may be requested by the applicant and held at the discretion of the town for the purpose of informing the representatives of construction projects of any local requirements, state environmental permitting requirements, and any additional limitations that may be imposed. Section 6.22.7 Technical Standards All applicants are required to develop and submit a storm water management plan prepared by a professional engineer licensed in the state. All storm water management plans must address storm water management on a site-by-site basis and all requirements of this article. All storm water management practices shall be consistent with the RISDISM and the state soil erosion and sediment control handbook, as amended.
(1) Performance standards. Storm water management plans shall incorporate structural and nonstructural best management practices for water quality control, in accordance with the state storm water design and installation standards manual. Development in special resource protection waters or watersheds of impaired waters as defined pursuant to the state water quality regulations may be held to higher standards. As part of such higher standards, low-impact development shall be used as the primary method of storm water control to the maximum extent practicable to manage water quality and maintain groundwater recharge to predevelopment levels.
(2) Disallowed storm water best management practices. The placement of storm water structures within a floodplain shall be avoided. If there is no alternative, the applicant must show what effects, if any, the tailwaters created by the floodplain will have on the outflow and effective storage capacity of the storm water best management practice.
(3) Facilitation of maintenance. Facilities that require maintenance shall be designed to minimize the need for regular maintenance, facilitate required maintenance, and ensure accessibility of components that require maintenance.
At a minimum, all storm water management plans must incorporate best management practices with appropriate maintenance design in accordance with the state storm water design and installation standards manual, as amended.
(4) Flood protection. Storm water management plans shall demonstrate that a proposed project provides for protection of life and property from flooding and flood flows. Water quantities must be controlled in accordance with the RISDISM, as amended, or a municipally approved regional storm water management plan for the watershed in which the project site is located. Storm water management plans shall demonstrate incorporation of the following standards into the proposed project: 6-60
a. Control and maintenance of post-development peak discharge rates from the 1-year, 2-year, 10-year, 25-year, and 100-year storm events to predevelopment levels.
b. Downstream analysis of the 100-year storm event and control of the peak discharge rate for the 100-year storm to mitigate downstream impacts.
c. Discharge from any storm water facility must be conveyed through properly constructed conveyance system to provide for nonerosive flows during all storm events. The proposed storm water conveyance system consisting of open channels, pipes, and other conveyance devices shall at a minimum accommodate the runoff from a 25-year storm event. The storm water conveyance system must provide for nonerosive flows to receiving waters.
(5) Surface water and groundwater. Storm water management plans shall, in accordance with the RISDISM, as amended, demonstrate that during development and post-development, all receiving waters will be recharged in a manner closely resembling predevelopment conditions and that the developed site will retain hydrological conditions that closely resemble of those prior to disturbance. The goal of the storm water design shall be that hydrologic conditions in each subwatershed match predevelopment conditions.
Where practicable, development and redevelopment projects should aim to reduce runoff volumes. This may include minimizing and eliminating impervious surface areas such as roads, parking, paving or other surfaces, encouraging infiltration of noncontaminated runoff, preventing channelization, encouraging sheet flow, and where appropriate, preserving, enhancing or establishing buffers along surface water bodies and tributaries. Section 6.22.8 Stormwater Management Plans (a) Calculations. In addition to the information required for the site plan the following information must also be included with the application, where applicable:
(1) The area of each subwatershed shall be identified on final site plans.
(2) The area of impervious surfaces (including all roads, driveways, rooftops, sidewalks, etc.) for each sub-basin as identified in the state storm water design and installation standards manual, as amended.
(3) Weighted curve numbers as determined using urban hydrology for small watersheds (USDA Soil Conservation Service, 1986 or as amended).
(4) Invert elevations for inlets and outlets. In addition, invert elevations shall be provided for all basins including permanent and/or flood pool stages, including peak discharge rates for each stage.
(5) The total volume capacity for all flood control and water quality best management practices (e.g., infiltration basin, detention basins, wet ponds, etc.).
Volumes must be segregated into permanent and flood pool stage volumes where applicable. Furthermore, the volumes of all sediment storage (basins, forebays, etc.) areas must also be provided. 6-61 (6) Predevelopment and post-development peak discharge rates and runoff volumes for the 1-year, 2-year, 10-year, 25-year, and 100-year frequency storm events for each subwatershed to each separate water or discharge point. The water quality volume (WQV) must also be calculated for each subwatershed. All relevant variables such as curve numbers and time of concentration, along with the supporting computations and worksheets must be included. The entire site shall be included in an evaluated subwatershed.
(7) Supporting calculations to demonstrate that the proposed development project will meet section 6.22.7.
(b) Narrative description. As part of the storm water management plan, the applicant shall include a discussion of the protection of environmental resource functions and values. The following outline is provided as guidance for preparing a narrative description for the storm water management plan. Depending on the size and scope of the proposed project, the amount of information required by the town may vary; therefore, it is advised to consult the town for specific requirements.
(1) Site description. General topography, soil types, current vegetative composition and relative abundance, existing infrastructure, and/or adjacent properties, identification of major resources (e.g., wetlands, groundwater, surface waters, etc.), name of receiving water(s), potential water quality and/or hydrologic impacts on resources.
(2) Site input data. Watershed characteristics, area of all impervious surfaces, total area of site, annual mean rainfall, runoff coefficients, curve numbers for various land uses, peak discharge rates.
(3) Land use planning and source control plan.
(4) Best management practices. Identify the type of best management practice(s) employed both during and post construction and justification for selection, including any deviation from the state storm water design and installation standards manual, as amended, and the potential effect on pollutant removal efficiency.
(5) Technical feasibility. Include sizing, location, hydraulic and environmental impacts. Alternatives, which were considered but determined not to be feasible, should also be discussed.
(6) Maintenance schedule of best management practices to be used, both during and post construction including frequency of inspection and maintenance. Section 6.22.9 Inspections for Stormwater Best Management Practices (BMPs)
The town shall have the right to inspect best management practices constructed after the passage of the ordinance from which this article is derived. Inspections shall address whether best management practices have been installed in accordance with approved storm water management plans. 6-62 Section 6.22.10 Operation and Maintenance Requirements for BMPs (a) Routine operation and maintenance and repair procedures. Routine maintenance shall be performed on a regular basis to ensure proper performance and may include such routine procedures as training of staff, periodic inspections, grass cutting elimination of mosquito breeding habitats, and pond maintenance in accordance with a storm water management plan approved pursuant to this article. Repair procedures may be required to correct a problem or malfunction of a best management practice and to restore the management practice's intended operation and safe condition.
Repairs may include such procedures as structural repairs, removal of debris, sediment and trash removal, erosion repair, snow and ice removal, fence repair, mosquito extermination, and restoration of vegetated and nonvegetated linings.
(b) General operation and maintenance standards for storm water best management practices. Maintenance design and maintenance procedures for all best management practices shall be documented in storm water management plans in accordance with the state storm water design and installation standards manual, as amended; or manufacturer's specifications. A maintenance schedule for each type of best management practice must be included in the storm water management plan. These schedules shall list the frequency and type of maintenance operations necessary along with the legally responsible party's name, address, and telephone number. The owner, as well as all future owners, shall be required to implement the maintenance schedule of the best management practices. If the storm water facility is to be deeded to the town, the applicant must obtain a letter from the town acknowledging maintenance responsibility and intent of ownership. Section 6.22.11 Maintenance Agreements (a) Maintenance agreements shall provide written, contractual documentation, which demonstrates compliance with this article and legal arrangements for the upkeep of storm water facilities to assure their proper function and safety in accordance with this article.
(b) After final construction is completed, the owner or responsible person shall maintain "as built" plans of storm water management practices located on site. The plans must show the final design specifications for all storm water management facilities and must be certified by a professional engineer.
(c) Maintenance agreements, which describe maintenance schedules and requirements, must be developed for each storm water management facility unless the facility is dedicated to and accepted by the town. Schedules shall be based on the complexity and frequency of maintenance needs and shall be subject to the approval of the town.
At a minimum, maintenance frequency should be in accordance with the RISDISM, as amended.
(d) Right of entry. Upon the presentation of credentials and other documents, as may be required by law, or if authorized by the owner or other party in control of the property, the Director of Public Works, Building Official, Zoning Officer, and other town representatives designated by the Building Official, Zoning Officer, or Director 6-63 of Public Works may enter upon privately owned property for the purpose of performing their duties under this article and may make or cause to be made such inspections as the town deems reasonably necessary.
(e) Record keeping for maintenance activities. Maintenance agreements shall include provisions for maintenance record keeping. All activities conducted in accordance with a maintenance agreement must be recorded in a work order and inspection log.
Timely updates of the log shall be the responsibility of the storm water management facility owner or other responsible party pursuant to this article. Review of the maintenance and inspection log shall be completed by the town to determine the effectiveness of operation, maintenance and safety activities. Reviews shall occur as part of each on-site inspection. Additional reviews may be made as deemed appropriate by the town.
(f) Responsibility for maintenance to assure function and safety. Appropriate maintenance to assure function and safety of storm water management facilities shall be the responsibility the owner or may be assumed by another party via a written contractual arrangement in accordance with this article.
(g) Alterations to maintenance agreements. Any alterations in maintenance responsibility or alterations to maintenance agreements must be either reviewed and approved by the planning board (as applicable) or building official or designee. If portions of the land serviced by a storm water management facility are to be sold, written contractual arrangements shall be made to pass all responsibility of the maintenance agreement to the purchaser and shall be subject to review and approval of the department of public works or designee. All alterations to maintenance agreements shall be made and recorded in accordance with this article. Section 6.22.12 Application Fees The town shall be empowered to collect fees from permit applicants, which are commensurate with the cost of administering this article. Section 6.22.13 Notification of Noncompliance If the authorized enforcement agent finds a violation of this article then a written notice from the authorized enforcement agent to compel correction shall be transmitted to the owner or operator. Such notice shall set forth the nature of corrections required and the time limit within which corrections shall be completed. Failure to comply with the required corrections within the specified time limit shall be considered a violation of this chapter. Section 6.22.14 Appeal of Notice of Noncompliance Any person receiving a notice of noncompliance may appeal the determination of the authorized enforcement agent. The appeal must be received within 30 days from the date of the receipt of the notice of noncompliance. The appeal shall be in writing and contain a detailed basis upon which the appeal was taken. The authorized enforcement agent shall then determine whether to accept the appeal or proceed to cause summons of the appellant in accordance with section 6.22.15. 6-64 Section 6.22.15 Penalties for Violation Any person who shall violate any provision of this article shall be punished in accordance with section 16.1. The authorized enforcement agent may, at the discretion of the court, undertake measures necessary to abate the violation and restore the property at the owner or operators expense. Section 6.22.16 Cost of Abatement of the Violation Within 30 days after abatement of the violation by or under the direction of the authorized enforcement agent, the owner or operator will be notified by the authorized enforcement agent of the cost of abatement, including administrative costs. If the amount due is not paid within a timely manner as determined by the authorized enforcement agent, the charges shall become a special assessment against the property and shall constitute a lien on the property for the amount of the assessment. Any person violating any of the provisions of this section shall become liable to the Town by reason of such violation. The liability shall be paid in not more than 12 equal payments. Interest at the rate of 12 percent per annum shall be assessed on the balance beginning on the 31st day following discovery of the violation. Section 6.22.17 Revocation or Suspension of Approval The approval of a storm water management plan under this chapter may be revoked or suspended by an authorized enforcement agent and all work on the development or redevelopment project halted for an indefinite time period after written notification is transmitted by the authorized enforcement agent to the owner or operator for one or more of the following reasons:
(1) Violation of any condition of the approved plan, or specifications pertaining thereto.
(2) Violation of any provision of this article.
(3) The existence of any condition or the performance of any act constituting or creating a nuisance, hazard, or endangerment to human life or property of others, or contrary to the spirit or intent of this article. Section 6.22.18 Remedies not Exclusive The remedies listed in this article are not exclusive of any other remedies available under any applicable federal, state or local law and it is within the discretion of the authorized enforcement agent to seek cumulative remedies. (Ord. of 6/13/2017) 6-65