Chapter 121 Stormwater Management

Establish minimum acceptable standards for stormwater management facilities within the Town of Cornwall. The obligation to meet these minimum acceptable standards shall be the sole responsibility of the person or entity proposing any new subdivision, development and/or site plan where such stormwater facilities will be required and utilized.

Meet the requirements of the SPDES general permit for MS4s.

Require land development activities to conform to the substantive requirements of the New York State SPDES general permit for construction activities, Permit No. GP-0-08-001 ("SPDES general permit for construction activities").

Minimize increases in stormwater runoff from land development activities in order to reduce flooding, siltation, increases in stream temperature, and stream bank erosion and maintain the integrity of stream channels.

Minimize increases in pollution caused by stormwater runoff from land development activities that would otherwise degrade local water quality.

Reduce stormwater runoff rates and volumes, soil erosion and nonpoint source pollution, wherever possible, through stormwater management practices and to ensure that these management practices are properly maintained and eliminate threats to public safety.

Given that improperly managed stormwater runoff can increase the incidence of flooding and erosion and thus adversely affect human life, flora and fauna, this chapter has the following objectives:

To protect, maintain and enhance both the immediate and long-term health, safety and general welfare of the citizens of the Town of Cornwall.

To prevent damage from flooding.

To protect, restore and maintain the chemical, physical and biological integrity of community waters.

To encourage protection of natural drainage systems, such as wetlands, and use them in ways that do not impair their beneficial functioning.

To protect, restore and maintain the habitat of fish and wildlife.

DEVELOPMENT or DEVELOPMENT ACTIVITY

To assure the attainment of these objectives by requiring the approval and implementation of stormwater pollution prevention plans (SWPPPs) for all regulated activities that may adversely impact surrounding areas.

§ 121-2 Definitions and word usage.

Interpretation and usage. Unless specifically defined below, words or phrases shall be interpreted so as to give them the meanings they have in common usage and to give this chapter its most effective application. Words used in the singular shall include the plural, and the plural shall include the singular; words used in the present tense shall include the future tense. The word "shall" denotes mandatory requirements; the word "may" is permissive.

Definitions. As used in this chapter, the following terms shall have the meanings indicated:

ADVERSE IMPACTS

Any modifications, alterations or effects on a feature or characteristic of public waters, wetlands or adjacent lands, including their quality, quantity, hydrology, surface area, species composition, living resources, aesthetics or usefulness for human or natural uses which are or may potentially be harmful or injurious to human health, welfare, safety or property, to biological productivity, diversity or stability or which unreasonably interfere with the enjoyment of life or property, including outdoor recreation.

AGRICULTURAL ACTIVITY

The activity of an active farm, including grazing and watering livestock, irrigating crops, harvesting crops, using land for growing agricultural products, and cutting timber for sale, but shall not include the operation of a dude ranch or similar operation, or the construction of new structures associated with agricultural activities.

APPLICANT

An owner or agent of an owner who has filed an application for a land development activity.

BUILDING

Any structure, either temporary or permanent, having walls and a roof, designed for the shelter of any person, animal, or property, and occupying more than 100 square feet of area.

CHANNEL

A natural or artificial watercourse with a definite bed and banks that conducts continuously or periodically flowing water.

CLEARING

Any activity that removes the vegetative surface cover.

DESIGN MANUAL

The New York State Stormwater Management Design Manual, most recent version, including applicable updates, which serves as the official guide for stormwater management principles, methods and practices.

DEVELOPER

Any person who engages in development either as the owner or the agent of the owner.

Construction, installation, alteration, demolition or removal of a structure, impervious surface or drainage system;

Clearing, scraping, grubbing or otherwise removing or killing the vegetation of a site; or

EROSION AND SEDIMENT CONTROL PLAN

Adding, removing, exposing, excavating, leveling, grading, digging, burrowing, dumping, piling, dredging or otherwise disturbing the soil, mud, sand or rock on a site which could otherwise cause deleterious conditions as noted hereinabove.

DRAINAGE SYSTEM

The system through which water flows from the land, including watercourses, water bodies, groundwater and wetlands.

A set of plans prepared by a licensed/certified professional indicating the specific measures and sequencing to be used to control sediment and erosion on a development site during construction.

EROSION CONTROL MANUAL

The most recent version of the "New York Standards and Specifications for Erosion and sediment Control" manual, commonly known as the "Blue Book."

GRADING

Excavation or fill of material, including the resulting conditions thereof.

IMPERVIOUS SURFACE

A surface which has been compacted or covered with a layer of material so that it is highly resistant to infiltration by water, including, but not limited to, semi-impervious areas such as compacted clay, conventionally surfaced streets, roofs, sidewalks, parking lots and other similar structures.

INFILTRATION

The process of percolating stormwater into the subsoil.

LAND DEVELOPMENT ACTIVITY

Construction activity, including clearing, grading, excavating, soil disturbance or placement of fill, that results in land disturbance of equal to or greater than one acre, or activities disturbing less than one acre of total land area that is part of a larger common plan of development or sale, even though multiple separate and distinct land development activities may take place at different times on different schedules.

MAINTENANCE AGREEMENT

A legally recorded document that provides for long-term maintenance of stormwater management practices amongst one or more lot owners.

NONPOINT SOURCE POLLUTION

Pollution from any source other than from any discernible, confined, and discrete conveyances, and shall include, but not be limited to, pollutants from agricultural, silvicultural, mining, construction, subsurface disposal and urban runoff sources.

NYSDEC

The New York State Department of Environmental Conservation.

OWNER

The person in whom is vested either a) the fee ownership, dominion or title of property; b) possession of property; or c) the responsibility to maintain property. This term may also include a tenant, if chargeable under his lease for the maintenance of the property, and any agent of the owner or tenant, including a developer.

PERSON

Any and all persons, natural or artificial, and includes any individual, firm, corporation, government agency, business trust, partnership, association, two or more persons having a joint or common interest or any other legal entity.

PHASING

Clearing a parcel of land in distinct pieces or parts, with the stabilization of each piece completed before the clearing of the next.

RECEIVING BODY OF WATER

Any water body, watercourse or wetland into which surface waters flow either naturally, in man-made ditches or in closed conduit systems.

REGULATED WETLAND

Any area meeting the requirements of the "Federal Manual for Identifying and Delineating Jurisdictional Wetlands" (latest edition), and/or any area mapped or delineated or otherwise designated by the NYSDEC as being a state-protected wetland. NYSDEC-regulated wetlands shall include the NYSDEC-regulated adjacent area.

SEDIMENT

The fine particulate material, whether mineral or organic, that is in suspension or has settled in a water body.

SEDIMENT CONTROL

Measures that prevent eroded sediment from leaving the site.

SITE

Any tract, lot or parcel of land, or combination thereof, which is under single ownership or is contiguous and in diverse ownership where development is to be performed as part of a unit, subdivision or project.

SPDES

The State Pollution Discharge Elimination System program, as codified in Article 17 of the New York Environmental Conservation Law, and the regulations and permits issued thereunder.

SPDES GENERAL PERMIT FOR CONSTRUCTION ACTIVITIES

An SPDES general permit issued by the NYSDEC which regulates disturbances of land resulting from construction activities. Any reference to the general permit is to the version in effect at the time of the review and approval of the SWPPP.

SPDES GENERAL PERMIT FOR MS4s

An SPDES general permit issued by the NYSDEC that requires municipalities to regulate discharges from municipal separate storm sewers. Any reference to the general permit is to the version in effect at the time of the review and approval of the SWPPP.

STABILIZATION

The use of practices to prevent exposed soil from eroding.

STORMWATER MANAGEMENT FACILITY

One or a series of stormwater management practices installed, stabilized and operating for the purpose of controlling stormwater runoff.

STORMWATER MANAGEMENT OFFICER

An employee or officer designated by the municipality to review and approve stormwater pollution prevention plans and to inspect sites subject to this chapter and to enforce its requirements. Plan reviews and site inspections may be delegated to a consulting engineer or a consultant. If the project is referred by the Town to a consulting engineer or consultant, the applicant shall deposit funds into an escrow account to defray the review costs. The amount of the deposit shall be determined by the Planning Board upon advice of the Board's consultants.

STORMWATER MANAGEMENT PRACTICES

Measures, either structural or nonstructural, that are determined to be the most effective, practical means of preventing flood damage and preventing or reducing point source or monopoint source pollution inputs to stormwater runoff and water bodies.

STORMWATER POLLUTION PREVENTION PLAN (SWPPP)

A set of plans prepared by or under the direction of a licensed/certified professional indicating the specific measures and sequencing to be used to control stormwater on a development site during and after construction.

STORMWATER RUNOFF

Stormwater flow on the surface of the ground resulting from rainwater, surface runoff, snowmelt and drainage.

STRUCTURE

That which is built or constructed, an edifice or building or any piece of work artificially built or composed of parts joined together in some definite manner, but shall not include fences or signs.

SURFACE WATERS OF THE STATE OF NEW YORK

Lakes, bays, sounds, ponds, impounding reservoirs, springs, wells, rivers, streams, creeks, estuaries, marshes, inlets, canals, the Atlantic Ocean within the territorial seas of the State of New York and all other bodies of surface water, natural or artificial, inland or coastal, fresh or salt, public or private (except those private waters that do not combine or effect a junction with natural surface or underground waters), which are wholly or partially within or bordering the state or within its jurisdiction. Storm sewers and waste treatment systems, including treatment ponds or lagoons which also meet the criteria of this definition are not waters of the state; this exclusion applies only to man-made bodies of water which neither were originally created in waters of the state (such as a disposal area in wetlands) nor resulted from impoundment of waters of the state.

WATER BODY

Any natural or artificial pond, lake, reservoir or other area which ordinarily or intermittently contains water and which has a discernible shoreline.

WATERCOURSE

A permanent or intermittent stream or other body of water, either natural or man-made, which gathers or carries surface water.

WATERSHED

A drainage area or basin contributing to the flow of water in a receiving body of water.

WATERS or PUBLIC WATERS

Any and all water on or beneath the surface of the ground. It includes the water in any watercourse, water body or drainage system. It also includes diffused surface water and water standing, percolating or flowing beneath the surface of the ground.

§ 121-3 Applicability and exemptions.

Unless exempted pursuant to Subsection C below, an SWPPP must be submitted and approved by the Stormwater Management Officer before:

A subdivision plat is approved by the Planning Board;

Site plan or special use permit approval is granted by the Planning Board;

An existing drainage system is altered, rerouted, deepened, widened, enlarged, decreased or obstructed; or

The issuance of a building permit.

Following the review and approval of the SWPPP by the Stormwater Management Officer, an applicant and the owner, and such other designated responsible party or parties, shall be responsible for the implementation and maintenance of the SWPPP.

Exemptions. The following development activities are exempt from the requirements of Subsections A and B above:

Land development activity which does not disturb more than one acre (43,560 square feet); provided, however, for projects which disturb between 10,000 square feet and 43,560 square feet, an erosion and sediment control plan shall be designed, approved, implemented and maintained as directed by the Stormwater Management Officer.

Agricultural activity; provided, however, that for such activities involving the construction of structures disturbing more than 10,000 square feet, an erosion and sediment control plan shall be designed, approved, implemented and maintained as directed by the Stormwater Management Officer.

Any maintenance, alteration, use or improvement to an existing structure not changing or affecting quality, rate or location of surface water discharge.

Silvicultural activities, provided that the guidelines and requirements of sound forestry management practices as established by the NYSDEC are met.

Routine maintenance activities that disturb less than one acre and are performed to maintain the original line and grade, hydraulic capacity or original purpose of a facility.

Repairs to any stormwater management facility deemed necessary by the Stormwater Management Officer or by the NYSDEC.

Cemetery graves.

§ 121-5 SWPPP preparation and contents.

Installation of fencing, signage, telephone and electric poles and other kinds of posts or poles.

(9)

Emergency activities necessary to protect life, property or natural resources.

(10)

Activities of an individual engaging in home gardening by growing flowers, vegetables and other plants primarily for use by that person and his or her family.

(11)

Landscaping and horticultural activities in connection with an existing structure.

(12)

Land development activities for which a building permit has been issued prior to the effective date of this chapter.

(13)

Land development activities in connection with any subdivision or site plan which has received conditional final or final approval from the Town of Cornwall Planning Board prior to the effective date of this chapter.

§ 121-4 SWPPP performance standards.

An SWPPP must demonstrate that the proposed development or activity has been planned and designed and will be constructed and maintained to meet each of the following standards:

To ensure that after development, runoff from the site maintains the rate of flow and quality of runoff that would have occurred following the same rainfall under existing conditions;

To maintain the existing hydraulic and characteristics of the watershed;

To protect the quality of surface waters;

To protect groundwater quality and levels;

To protect the beneficial functioning of wetlands as areas for the natural storage of surface waters and the chemical reduction and assimilation of pollutants;

To prevent increased flooding and damage that results from improper location, construction and design of structures in areas that are presently subject to an unacceptable danger of flooding;

To minimize injury to flora and fauna and adverse impacts to fish and wildlife habitat; and

To further the objectives of this chapter.

It is the applicant's responsibility to include sufficient information in the SWPPP for the Stormwater Management Officer or his designate to evaluate the environmental characteristics of the affected areas, the potential and predicted impacts of the proposed activity on public waters and adjacent lands, and the effectiveness and acceptability of those measures proposed by the applicant for reducing adverse impacts. The SWPPP shall contain all material necessary to communicate the information required by this section.

All calculations, assumptions, criteria and references used in the design of new facilities, examination of existing facilities and comparison of pre- to post-development discharges shall be included with the plan.

All stormwater management data must be prepared and sealed by individuals licensed or certified in New York State to perform such duties.

The SWPPP shall contain the name, address and telephone number of the owner and the developer. In addition, a survey prepared by a surveyor licensed in New York State and a legal description of the property shall be provided, and its location with reference to such landmarks as major water bodies, adjoining roads, railroads, subdivisions or other municipalities shall be clearly identified on a location map.

The existing environmental and hydrologic conditions of the site and of receiving waters and wetlands shall be described in detail, including the following:

A plan showing the pre-development conditions of the site at a scale of at least one inch equals 50 feet and a map at a scale of at least one inch equals 500 feet showing all contributory drainage areas to the study point, or such other scale as deemed appropriate by the Stormwater Management Officer.

The flow rate of stormwater runoff under existing conditions.

The names and description of all watercourses, water bodies and wetlands on or adjacent to the site or into which the stormwater flows. Information regarding the existing water quality, if any, and the receiving water quality classification as determined by the NYSDEC shall be included.

Groundwater levels from readily available data sources.

The location of floodplains.

Land cover.

Topography at two-foot contour intervals, based on actual data.

Soils, including erodibility, percolation rate, depth to groundwater and depth to bedrock, etc.

Proposed alterations of the site shall be described in detail and shown on plans at a scale of at least one inch equals 50 feet, or such other scale as deemed appropriate by the Stormwater Management Officer, and shall include:

Changes in topography, with all grading shown with two-foot contour intervals or less;

Limits of proposed disturbed area;

Proposed ground coverage, i.e., pavement, gravel, houses, buildings, lawns, etc., and their areas;

Construction phasing plans describing the intended sequence of construction activities, including clearing and grubbing, excavation and grading, utility and infrastructure installation and any other activity at the site that results in soil disturbance. Consistent with the Erosion Control Manual, no more than five acres shall be disturbed at any one time unless a waiver for such excess disturbance has been granted by the NYSDEC;

Description of the pollution prevention measures that will be used to control litter, construction chemicals and construction debris from becoming a pollutant source in stormwater runoff;

Description of construction and waste materials expected to be stored on site, with updates as appropriate, and a description of controls to reduce pollutants from these materials, including storage practices to minimize exposure of the materials to stormwater, and spill prevention and response;

Temporary and permanent structural and vegetative measures to be used for soil stabilization, runoff control and sediment control for each stage of the project from initial land clearing and grubbing to project closeout;

A site map/construction drawing(s) specifying the locations, size and length of each erosion and sediment control practice;

(9)

Dimensions, material specifications and installation details for all erosion and sediment control practices, including the siting and sizing of any temporary sediment basins;

(10)

Temporary practices that will be converted to permanent control measures;

(11)

Implementation schedule for tagging temporary erosion and sediment control practices, including the timing of initial placement and duration that each practice should remain in place;

(12)

Maintenance schedule to ensure continuous and effective operation of the stormwater management practices and stormwater management facilities;

(13)

Name(s) of the receiving water(s);

(14)

Delineation of SWPPP implementation responsibilities for each part of the site;

(15)

Description of structural practices designed to divert flows from exposed soils, store flows, or otherwise limit runoff and the discharge of pollutant from exposed areas of the site to the degree attainable; and

(16)

Any existing data that describes the stormwater runoff at the site.

All components of the drainage system and any measures for the detention, retention or infiltration of water or for the protection of water quality shall be described in detail, including:

The channel, direction, flow rate and quality of stormwater that will be conveyed from and/or through the site, with a comparison to the existing conditions. In no case will any facility or construction be allowed that raises the existing water surface elevation on upstream or downstream properties, unless specifically agreed to by those property owners;

Detention, retention and/or infiltration structures, including plans for the discharge of contained waters, and maintenance plans.

A tabulation of water quality volumes and storage, discharge curves with corresponding water surface elevations, inflow hydrographs, outflow hydrographs and dewatering/infiltration times shall be submitted with all plans utilizing detention, retention and infiltration facilities.

All plans, with defined subcatchment areas, and profiles of the proposed drainage facilities, including the size and type of material.

An erosion and sediment control plan for all development activities.

All calculations and design information in accordance with the design section of this chapter and as may be required pursuant to the SPDES general permit for construction activities or the SPDES general permit for MS4s, as in effect at the time of the review.

General specifications for the construction of all components of the drainage system.

Any other information that the Stormwater Management Officer or his designated representative determines is reasonably necessary to evaluate the SWPPP or to meet the requirements of this chapter.

All charges for the technical review of the SWPPP shall be charged against the applicant's escrow. If the escrow is depleted, the applicant must pay all charges prior to the final approval of the SWPPP.

§ 121-6 Design standards.

To ensure attainment of the objectives of this chapter and to ensure that performance standards will be met, the design, construction and maintenance of drainage systems shall be consistent with the following standards:

In the interest of reducing the total area of impervious surface, preserving existing features that are critical to stormwater management, and reducing the concentration of stormwater flow, maximum use shall be made of existing on-site natural and man-made stormwater management facilities.

Innovative stormwater management facilities may be proposed (e.g., rooftop storage, underground storage structures and infiltration systems), provided that they are accompanied by detailed engineering plans and demonstrate performance capabilities that are acceptable to the Stormwater Management Officer.

Stormwater management facilities shall be provided so the peak discharge of the calculated post-development runoff to an adjacent property, watercourse or water body does not exceed the peak discharge of the pre-development runoff. Point discharge of stormwater runoff to an adjacent property, watercourse or water body will not be allowed in the post-development design if one did not exist in the predevelopment condition. Point discharge is required to be returned to sheet flow or an easement will be required to be obtained from the adjoining property owner if this condition cannot be met.

Runoff calculations for the pre-development and post-development comparison shall consider the one-year, ten-year, twenty-five-year, and one-hundred-year storm frequencies.

For pre-development computations, the runoff coefficient within the study area shall be based on present land use conditions.

Retention and detention basins in compliance with NYSDEC standards and guidelines, and other approved alternatives, shall be used to retain and detain the increased and accelerated runoff and reduce pollutants in runoff that the development generates. Water shall be released from these areas at a rate equal to or less than the pre-development conditions of the storm event. Measures shall be taken to protect the outfall area from erosion. Water quality volume shall be addressed by any proposed post-development design.

Retention/detention basins shall be designed to safely discharge the peak discharge from the post-development one-hundred-year storm frequency event through an emergency spillway in a manner which will not damage the integrity of the basin or cause damage to adjoining properties.

Retention/detention basins shall be landscaped in accordance with current engineering practices and in accordance with the Erosion Control Manual, latest edition or revision.

Retention/detention basins that may be used to collect sediment during construction must have all sediment removed at any time that it is at 60% of its original capacity. Upon completion of all construction, any sediment in the basin must be removed and the basin shall be reshaped to the design dimensions and stabilized. A maintenance schedule must be provided indicating how often the basin is to be cleaned thereafter and who is responsible for cleaning it.

Retention/detention basins that are designed with a dam shall incorporate the following minimum standards:

The maximum water depth shall not exceed 10 feet unless approved by waiver of the Planning Board.

The minimum top width of dams shall be 10 feet.

The side slopes of earth fill dams shall not be steeper than three feet horizontal to one foot vertical on the downstream side of the embankment.

Basins without restricted access shall have impoundment areas with side slopes no greater than five feet horizontal on one foot vertical.

A cutoff trench of impervious material shall be provided under all dams.

All pipes and culverts through dams shall have properly spaced cutoff collars or factory-welded antiseep collars.

A minimum of one foot freeboard, computed from the maximum water surface elevation during the one-hundred-year storm event, shall be provided in all basins.

The minimum floor elevation of all structures that would be affected by a basin or other water impoundments or open conveyance systems where ponding may occur shall be two feet above the one-hundred-year water surface elevation.

Runoff calculations for stormwater management facilities shall be based upon the following methods:

SCS - TR-20 (latest revision) is the recommended and preferred method for the study of watersheds with a drainage area greater than 100 acres. SCS - TR-20 or SCS - TR-55 Tabular Hydrograph Method (latest revision) may be used for the study of watersheds with a drainage area greater than 200 acres.

SCS - TR-55 Graphical Peak Method (latest revision) may be used in lieu of the Tabular Hydrograph Method for sizing conveyance systems or checking peak flows only. It shall not be used for basin routing or subarea routing as it does not provide an adequate hydrograph.

Other standard engineering models with approval of the Stormwater Management Officer.

Stormwater runoff shall be based on the following twenty-four-hour storm events with a Type III distribution:

	Storm Event	Inches of Rainfall
	1-year	2.9
	10-year	5.5
	100-year	8.0

source: SCS Technical Release 55

Use of other criteria, assumptions, references, calculation methods and computer programs may be utilized, provided that detailed design information and programming, with references, are submitted to and found acceptable by the Stormwater Management Officer prior to submission of the SWPPP.

The design plan and construction schedule shall incorporate measures to minimize soil erosion and sedimentation.

Consideration shall be given to the relationship of the subject property to the drainage pattern of the watershed.

Stormwater runoff shall not be transferred from one watershed to another unless:

The watersheds are subwatersheds of a common watershed which join together within the perimeter of the property;

The effect of the transfer does not alter the peak discharge onto adjacent lands, watercourse or water bodies at any point; and

Easements from the affected landowners are provided, if deemed necessary by the Stormwater Management Officer.

Technical references. For the purpose of this chapter, the following documents shall serve as the official guides and specifications for stormwater management. Stormwater management practices that are designed and constructed in accordance with these technical documents shall be presumed to meet the standards imposed by this law:

The Design Manual, latest version.

The Erosion Control Manual, latest version.

Technical standards.

For all swales and gutters, the Manning's roughness coefficient "n" factors used to determine capacity and velocity shall be based on accepted engineering practices.

Corrugated metal pipe will not be allowed to be used in any drainage system or facility without the approval of the Town Superintendent of Highways, the Stormwater Management Officer and the Town Engineer. If allowed, corrugated metal pipe shall be fully asphalt-coated with paved inverts, and the "n" factor shall be twenty-two thousandths (0.022) for annular pipe and seventeen thousandths (0.017) for helical pipe.

The "n" factor for concrete pipe shall be thirteen thousandths (0.013).

The "n" factor for polyethylene pipe shall be ten thousandths (0.010) for smooth interior pipe and nineteen thousandths (0.019) for corrugated interior pipe.

Manufacturer's specifications may be submitted to the Stormwater Management Officer and Town Engineer for acceptance if other types of pipes or sizes of pipes indicate that another value of "n" should be used.

Catch basins shall be designed with a sump of 16 inches.

Catch basin inlet capacity shall be based on design data provided by the manufacturer.

Any existing drainage structures within 200 feet of the site shall be included in the SWPPP. Structures that convey streams shall be checked to determine if they have the capacity to carry the fifty-year storm flow, and all other structures shall be checked for capacity to carry the twenty-five-year storm flow.

(9)

A tabulation of flows through all drainage systems shall be submitted with the plans.

(10)

Culvert design shall consider inlet/outlet control at each structure or hydraulic losses shall be calculated through the system. These calculations are to be submitted as part of the SWPPP. At a minimum, when pipe sizes change, the tops of the pipes shall match in elevation.

(11)

All culverts having diameters of 24 inches to 48 inches shall have a removable inlet grating of five-eighths-inch diameter (minimum) reinforcing bars spaced approximately six inches on center. All design calculations are to reflect this inlet control condition.

Catch basins shall be located in the swale along open section roadways. The calculated depth of flow in the swale shall not exceed 1/2 of the total depth of the swale before placing a catch basin. The catch basin shall be capable of accepting 100% of the flow in the swale, based on a twenty-five-year return frequency storm event. On closed section roadways, catch basins shall be located along the curbline and are not permitted along the curb radius at intersections. For the purpose of catch basin placement, the depth of flow along the curb and across intersections shall not exceed two inches.

Manholes and catch basins shall not be spaced more than 300 feet apart. Structures shall be placed at all points of changes in horizontal or vertical direction.

Stormwater collection systems shall have a minimum diameter of 15 inches and shall be designed to have a minimum velocity of two feet per second. However, at the terminus of the system, the flow velocity at the discharge point shall not exceed four feet per second prior to the flow entering a natural watercourse, water body or adjacent property.

The maximum swale, gutter or curb velocity of stormwater runoff shall be maintained at levels that result in a stable condition both during and after construction. Swales shall be designed and stabilized in accordance with the Erosion Control Manual. Swales shall be designed to allow for infiltration of stormwater runoff and removal of pollutants from the runoff whenever possible. This can be accomplished by keeping the swale at as flat a slope as possible, stabilizing the swale with a water-tolerant erosion-resistant grass that will not be mowed close to the ground, increasing the percolation ability of the swale by tilling the soil before establishing vegetative cover and installing check dams with riprap on the downstream side to prevent scouring.

Stormwater management facilities that are not offered for dedication to the Town and not located within a public right-of-way shall be located within an area subject to a drainage easement.

When applications are submitted in separate sections, each section shall control stormwater runoff and sedimentation as though it were a separate entity. If temporary facilities are required for construction of a section, they shall meet all of the requirements of this chapter. A construction or phasing schedule shall be submitted with each SWPPP and shall demonstrate the methods to be used to minimize stormwater runoff and soil erosion and sedimentation.

Stormwater management facilities shall not be constructed within or discharge directly to a regulated wetland, adjacent areas or existing water bodies unless:

The appropriate permits or approvals from all applicable regulatory agencies for any disturbances to such regulated resources have been obtained; or

A letter from said agencies has been obtained stating that a permit is not required for the proposed work; and

Copies of such permits or letters shall be submitted to the Stormwater Management Officer prior to the final approval of the SWPPP.

Individual lots, buildings and dwellings shall be provided with drainage facilities to assure proper runoff from roofs, driveways, paved areas and footing drains. Footing drains shall discharge to free-flowing outlets. The installation of such facilities shall be in accordance with the requirements of this chapter and the Town of Cornwall Road Specifications[1] and must be installed prior to the issuance of a certificate of occupancy.

[1]

Editor's Note: See Ch. A161, Road Specifications for Town Roads.

Any land development activity shall not cause an increase in turbidity that will result in substantial visible contrast to natural conditions in surface waters of the state of New York.

Stormwater discharges should be consistent with the thermal criteria found in the Water Quality Regulations, 6 NYCRR Part 704.

AA.

Contractor certification.

Each contractor and subcontractor identified in the SWPPP who will be involved in soil disturbance and/or stormwater management facilities installation shall sign and date a copy of the following certification statement before undertaking any land development activity:

"I certify under penalty of law that I understand and agree to comply with the terms and conditions of the Stormwater Management Plan. I also understand that it is unlawful for any person to cause or contribute to violation of water quality standards."

The certification must include the name and title of the person providing the signature, address, and telephone number of the contracting firm; the address (or other identifying descriptions) of the site; and date the certification is made.

The certification statement(s) shall become part of the SWPPP for the land development activity.

BB.

In the event of any conflict between the requirements of this chapter and the SPDES general permit for construction or the SPDES general permit for MS4s, the requirements of the SPDES general permits shall control.

§ 121-7 Easements and maintenance.

The applicant shall reserve easements or drainage rights-of-way within the subdivision or site plan where stormwater management facilities are existing or proposed, whether man-made or natural. Easements shall conform as closely as possible to the lines of such course and shall also meet the following criteria:

Easements shall have a minimum width of 20 feet and shall be adequately designed to provide area for the collection and discharge of water, the maintenance and repair of the facility, and the passage of equipment for such work.

In the case of streams or open-channel drainage, the easement shall encompass the one-hundred-year storm event or the flood of record, plus one foot freeboard above that elevation. Calculations acceptable to the Stormwater Management Officer supporting those elevations shall be submitted with the SWPPP.

When a proposed drainage system carries water onto adjacent lands where no discharge point existed in the pre-developed condition, stormwater will be returned to a sheet flow condition prior to exit from the site, or an easement must be obtained from the downstream property owners(s).

The SWPPP and easements shall clearly indicate who has the right of access and the responsibility of maintenance for all stormwater management facilities.

The stormwater management facilities maintained by the owner or other responsible entity shall be subject to adequate easements to permit the Town to inspect and, if necessary, to take corrective measures should the owner fail to properly maintain the system.

Maintenance. Unless the Town Board determines to accept the responsibility of maintaining the stormwater management facilities, it shall be the responsibility of the owner and subsequent landowners, if applicable, to maintain the proposed stormwater management facilities as it was designed and constructed, in accordance with the following minimum requirements:

As specified in an approved SWPPP, good maintenance involves periodic cleaning and dredging of pipes and basins and mowing and maintaining proper land cover. Sediment shall be removed from sediment traps or sediment ponds whenever their design capacity has been reduced by 50%.

The stormwater management facilities installed in accordance with this chapter shall be operated and maintained by the owner to achieve the goals of this chapter. Proper operation and maintenance also includes, as a minimum, the following:

(a)

A preventive/corrective maintenance program for all stormwater management facilities and systems of treatment and control (or related appurtenances) that are installed or used to achieve the requirements of this chapter.

(b)

Written procedures for operation and maintenance and training new maintenance personnel.

Stormwater management facilities and related improvements may become part of a drainage district upon the approval by the Town Board in accordance with the procedures set forth in Article 12 of the New York Town Law, in which case the maintenance of the stormwater management facilities and related improvements shall be the responsibility of the Town.

Maintenance agreements. If the future maintenance of stormwater management facilities shall be the responsibility of more than one owner or entity, a maintenance agreement for stormwater management facilities, in form and content acceptable to the Stormwater Management Officer and attorney for the Town and binding on all subsequent landowners, must be recorded in the office of the County Clerk prior to the issuance of any final plan or plat approval.

§ 121-8 Performance security.

Performance security to ensure that the initial construction of stormwater management facilities and related improvements shall be provided in an amount approved by the Town Board upon the recommendation of the Stormwater Management Officer and in a form approved by the attorney for the Town. The applicant's engineer or licensed or certified design professional shall prepare the estimate and submit it to the Stormwater Management Officer for review and recommendation to the Town Board.

The estimated costs of the following improvements associated with the SWPPP or erosion and sediment control plan must be included in the amount of the performance security:

Stormwater management facilities, including but not limited to catch basins, manholes, pipes, swales, basins, infiltration systems;

Erosion and sediment control, including grading and stabilization;

As-built or record drawings; and

Any other items that may be required by the Stormwater Management Officer.

Performance security shall be delivered to the Town Clerk, with copies provided to the Stormwater Management Officer and the Building Inspector, to guarantee to the Town that the developer will construct and complete the required public improvements, within a reasonable time as determined by the Stormwater Management Officer.

Prior to construction, and, if the stormwater management facilities are a component of an application before the Planning Board, then prior to the Planning Board's grant of final approval of a subdivision plat or site plan, the applicant shall follow the procedure set forth below:

In an amount set by the Town Board, the applicant shall either file with the Town Clerk a certified check to cover the full cost of the required improvements or an adequate and acceptable security issued by a bank or surety company approved by the Town Board to cover the full cost of the required improvements, or any combination thereof. Any such security shall comply with the requirements of § 277 of the Town Law and, further, shall be satisfactory to the Town Board and the Town Attorney as to form, sufficiency, manner of execution and surety. A period of three years shall be set forth in the document of surety within which required improvements must be completed. However, the term of such performance security may be required to be extended and the amount of the security increased by the Town Board if improvements are not completed within the original term of the security.

If the improvements are dedicated to the Town, then the required improvements shall not be considered complete until the installation of the improvements has been accepted by the Town and the Stormwater Management Officer has accepted as-built or record drawings.

The applicant shall complete all required improvements or post the required performance security, prior to the issuance of any building permits.

The performance security shall be released by the Town Board upon the statement of the Stormwater Management Officer that the requirements of this chapter have been met.

The Stormwater Management Officer shall not approve an SWPPP unless and until the attorney for the Town advises that the applicant has established a financial mechanism to ensure that any subsequent landowners shall have the financial ability to maintain the stormwater management facilities. Should the owner propose to transfer ownership and management responsibility to another entity, such as a homeowners' association, the owner must indicate how the other entity shall meet its obligation to maintain the stormwater management facilities and how it will bear the financial burden of meeting this obligation. The Stormwater Management Officer may, at his discretion, require that maintenance security in the form of an irrevocable letter of credit, cash or bank or certified funds drawn on a national or state bank be posted to meet this obligation. The amount of the financial security shall be equal to the estimated cost of maintain the system for a period of five years.

[Amended 1-9-2017 by L.L. No. 1-2017]

§ 121-9 Inspections.

The Stormwater Management Officer shall not approve the SWPPP unless adequate provisions have been made for inspection of the property. The applicant shall arrange with the Stormwater Management Officer for scheduling the following inspections:

Initial inspection prior to approval of the SWPPP, which inspection may be waived at the discretion of the Stormwater Management Officer;

Periodic construction inspection to be made during construction of underground drainage structures and during construction of any basin dams;