Source: https://ecode360.com/13789278
Timestamp: 2020-02-24 20:44:55
Document Index: 342756932

Matched Legal Cases: ['§ 400', '§ 400', '§ 400', '§ 400', '§ 400', '§ 400', '§ 400', '§ 400', '§ 1']

Village of Roslyn, NY Stormwater Management and Erosion Control
Ch 400 Art I Design Requirements
§ 400-1 Findings; purpose.
§ 400-2 Plans required.
§ 400-3 Drainage criteria.
§ 400-4 Drainage review requirements.
§ 400-5 Erosion and sediment control.
§ 400-6 Stormwater storage and treatment facilities.
§ 400-7 Penalties for offenses.
Chapter 400 Stormwater Management and Erosion Control
Article I Design Requirements
[Adopted 3-21-2006 by L.L. No. 2-2006 (Ch. 22-A of the 2000 Code)]
Regulating the quantity and quality of stormwater runoff stored and recharged, and the means of collecting and transmitting stormwater, is essential to maintaining the safety and public welfare of the Village of Roslyn and its residents. Regulating and improving the quantity and quality of the stormwater recharged into the ground and discharged into Hempstead Harbor or tributaries of Hempstead Harbor are vital to preserving the quality of Long Island's drinking water supply and the designated Significant Coastal Fish and Wildlife Habitat associated with Hempstead Harbor and the Hempstead Harbor Creek. The purpose and objectives of this article are to improve and regulate stormwater management and erosion control management within the Village resulting in the enhancement of the stormwater quality which recharges into the ground and discharges into Hempstead Harbor in accordance with the Village's responsibilities associated with Stormwater National Pollutant Discharge Elimination System (NPDES) Phase II Regulations.
Plans submitted for review. Plans submitted shall be submitted to the Department of Public Works for its review and shall consist of a plot plan, drainage plans, erosion and sedimentation control plan and profile plans where applicable.
The drainage plan shall include both existing and proposed topographic information plotted at two-foot intervals for the property proposed for development and the immediate surrounding area. Where required, information may need to be provided to assess any contribution from outside sources that may contribute runoff to the site proposed for development. The property shall not be regraded for the purpose of directing site runoff to off-site areas.
The drainage plan shall show all means of collecting property runoff whether by means of catch basins, area drains, swales, roof drains or other collection devices. The drainage plan shall also show adequate information for the analysis of the drainage system directing runoff to collection areas. Information to be provided shall include, at a minimum, types of drainage structures, inlet elevations, pipe inverts, pipe sizes and gradients. Applicable drainage details are to be shown on separate sheets of the subdivision plans. For any subdivision proposing the creation of a stormwater basin or basins, a separate plan shall be included for each basin delineating the proposed configuration and is to include all details of structures or devices proposed for directing and storing runoff, location and details pertaining to plant screenings and fence details. The stormwater basin plan shall show the proposed high-water mark utilized in determining the storage proposed for that basin. The plans shall show locations of all drainage reserve areas (DRAs) proposed for the storage of runoff, including shape, elevations and contours, for the assessment of storage capacity. The drainage plan shall also include all calculations pertaining to the assessment of the storage requirement for the subdivision on the plans. Additional information may be requested to justify the assumptions concerning flows from outside areas, flow capacities for specific pipe diameters and storage of runoff.
Erosion and sedimentation control plan. The erosion and sedimentation control plan shall include details to be enacted during construction to prevent or limit the migration of sediments from the site as a result of construction practices. The plan shall also include details showing the protection measures to be utilized to prevent sediment contamination of any on-site or applicable off-site drainage structures. The methods proposed shall conform to the New York State Stormwater Management Design Manual and the New York Standards and Specifications for Erosion and Sediment Control. The institution and enactment of these measures during construction are solely the responsibility of the developer.
Profile plan. The profile plan, for subdivisions where roads are proposed, shall include proposed stations, gradients and pertinent data necessary to define any proposed vertical curves, including overall length. Drainage structures and interconnecting pipes are to be plotted corresponding to the information shown on the drainage plan. All information pertaining to the roadway drainage system is to be included, such as pipe sizes, gradients and inverts, surface grades for structures and applicable location associated with roadway stations. Other information may be included if it assists in the analysis.
On-site drainage storage requirement.
Developers are responsible for providing storage for eight inches of runoff from the subdivision's tributary area, whether contributed from on-site or off-site sources. The storage can be provided through construction of stormwater basins, drainage reserve areas, installation of dry wells, or by other storage devices deemed acceptable by the Village. The storage volume requirement is to be determined utilizing the following formula:
Volume = A x C x 8"/12"
Tributary area in square feet.
Runoff coefficient determined.
The engineer representing the developer shall provide the following information to the Village for the analysis of the storage requirement:
Tributary map including contour information.
Tributary area calculations.
Runoff coefficients for property. Sample runoff coefficients:
Roof, concrete, asphalt and other impervious surface: C = 1.00.
Water (swimming pool, pond or lake) surface: C = 1.00.
Gravel roadway, earth or fill surfaces: C = 0.75.
Natural grass areas: C = 0.15.
Wooded (forest canopy) area: C = 0.10.
Managed landscape areas: C = 0.20.
Waiver of storage requirement.
The Village is aware that conditions may exist which could affect the potential of providing the storage required herein for specific sites. The developer may request a waiver of a portion of the storage requirement. A letter outlining the hardship and limitations for reaching the potential storage goal shall be forwarded to the Village for consideration. The letter shall include the following information:
Volume of stormwater runoff to be retained on site.
Destination of stormwater overflow from subdivision's property.
Municipality responsible for accepting the overflow.
Justification for the failure to meet the Village's storage requirement.
Should the proposed subdivision direct overflow runoff into water bodies under the jurisdictional control of the New York State Department of Environmental Conservation (NYSDEC), the developer will be required to forward a copy of any permits required by NYSDEC pertaining to the overflow.
The Village will evaluate the information submitted and will consider the request. However, developers are responsible for providing the maximum amount of storage the site permits in an effort to attain the eight-inch requirement.
Where the Village concurs with the hardship, the developer will be primarily required to install a stormwater treatment system to improve water quality and runoff volume and secondarily will be subject for the payment of compensation to the Village. Stormwater treatment units shall be designed to meet the requirements of stormwater treatment criteria outlined herein and with current general best management practices (BMPs). If the installation of a stormwater treatment system is not feasible, the Village will seek compensation as follows for improvements relative to water quality and flood mitigation elsewhere within the Village. For waiver where the on-site storage is less than eight inches but is five inches or greater, there will be no fee. However, if the volume of storage provided under the design is less than five inches of runoff from the tributary area, the developer is responsible for paying compensation to the Village for the volume of storage less than five inches. The fee payable to the Village per every 1,000 cubic feet of storage deficient of not meeting the Village's standard shall be determined by resolution of the Board of Trustees. If the developer chooses to pay the compensation, the following note is to be included on the street grading and drainage plan: "The developer will pay a fee of ________ to the Village of Roslyn as compensation for a partial waiver of drainage requirements, upon approval of the subdivision."[1]
The fee is assessed to compensate the Village for the added maintenance cost incurred as a result of accepting responsibility for the maintenance of the site overflow associated with the stricter control of runoff mandated by federal regulations enacted under Phase II of the Stormwater Discharge Program and as may be amended. Where sites overflow solely to facilities maintained by municipalities other than the Village, the developer shall be responsible for providing the storage of runoff that satisfies that municipality's requirement. A letter from the municipality holding jurisdiction shall be forwarded to the Village stating that the municipality is willing to accept the overflow runoff. This letter is required prior to the Village's agreement to any reduction in the eight-inch storage requirement. The Village will not approve any waiver for less than two inches of storage on site.
A plot plan shall be submitted showing metes and bounds of subdivision property and individual lots. The plot plan shall be stamped and signed by a licensed surveyor or licensed professional engineer.[1]
A drainage plan shall be submitted containing sufficient information to determine if the Village drainage requirements have been met. The drainage plan is to be stamped and signed by a licensed professional engineer.[2]
The plot plan and drainage plan shall include a key map showing the general location of the proposed subdivision.
The minimum scale for the plot plan and drainage plan shall be one inch equals 100 feet.
A North arrow shall be included on the plot plan and drainage plan.
The plot plan and drainage plan shall provide consistent information.
Profile plan grades shall be defined by center-line elevations, waterline grades or top of curb grades. The plan(s) shall denote proper designation.
The drainage plan and profile plan shall show locations of proposed drainage structures and proposed drainage pipe. Information shall be consistent.
Drainage structures, pipe diameters and inverts shall be identified on the profile plan.
Elevations shall conform to Nassau County's datum. A note indicating datum shall be placed on plans.
The drainage plan shall include existing and proposed contour elevations set at two-foot increments.
The plans shall contain appropriate notes designating dedication of roadways, easements, conservation areas, stormwater basins, drainage reserve areas, or other applicable easements.
Minimum drainage easements shall be 10 feet in width.
Location of sanitary sewers and utilities is to be shown on the plot plan or separate sewer plan.
Test holes are required at proposed stormwater storage site(s). A representative of the Village shall be on site to witness the results of test holes. Test hole log information is to be included on plans in subsequent plan submissions.
Approvals, where applicable, shall be required from New York State Department of Transportation, New York State Department of Environmental Conservation, or other authorities holding jurisdiction as might be required by the site. It is the responsibility of the engineer acting as agent for the developer to determine if an approval is required from any agency having interest. Copies of approvals or permits required by these authorities are to be forwarded to the Village.[3]
All areas regulated by the New York State Department of Environmental Conservation shall be defined on the drainage plan.
Drainage pipe design criteria.
Drainage pipe shall be of sufficient diameter and set at an appropriate gradient to accommodate the flow determined by the requirements of the tributary area.
Minimum size pipe on Village roads shall be 18 inches for collector systems. Fifteen-inch pipe may be allowed for crossover from single-unit catch basins and leaching pools.
Minimum cover over drainage pipe is 2.0 feet.
The grade for the same diameter pipe shall not be flattened after steep gradients.
Maximum velocity in pipes shall be 12 feet per second.
Minimum velocity in pipes shall be 2.5 feet per second.
Maximum pipe gradient shall be 6%.
Minimum pipe gradient shall be 0.2%
Inverts of pipes at catch basin are to be located at a sufficient depth to provide no conflict with the catch basin's deck.
A minimum spacing of 10 feet is required between drainage pipes and water supply lines.
Pipe material shall be selected and designed for proper strength relative to loading conditions.
The design of drainage pipes, conduits or ditches is to be performed by the use of the Manning Formula:
Velocity of flow (feet per second).
Manning roughness coefficient (no unit); example: n = 0.013 for precast reinforced concrete pipes.
Hydraulic radius (feet).
Slope of the pipe (feet per feet).
Drainage manholes.
Maximum distance between manholes shall be 350 feet.
The design and material standards for drainage manholes shall be consistent with the requirements of the Nassau County Department of Public Works (NCDPW).
Maximum height of a NCDPW Type 1 manhole is 10 feet.
Manholes greater than 10 feet in depth shall be NCDPW Type 2.
Differential distance between inverts for drop manholes shall be no more than 2 1/2 times the diameter of the inlet pipe.
The design and material standards for catch basins shall be consistent with the requirements of the Nassau County Department of Public Works (NCDPW).
The maximum tributary area for a NCDPW Type A or B catch basin is 4.5 acres.
The maximum tributary area for a NCDPW Type C or D catch basin is 9.0 acres.
Flow-through catch basins are to be NCDPW Type B or D.
Catch basin inlet elevations are to be shown on the drainage plan and the profile plan.
Maximum depth of catch basins is 10 feet.
Catch basins located on roadways with gradients greater than 5% require the basin to be recessed. An additional basin shall be located 20 feet downgrade of a recessed basin. A detail of a recessed basin shall be included on the plans.
Maximum two catch basins are allowed to be interconnected in a drainage system; thereafter a proposed drainage manhole structure is required.
A detail is required showing modifications of existing catch basins.
Yard inlets.
Structure shall be constructed of reinforced concrete material.
Minimum required interior dimension is 24 inches by 24 inches (or 24 inches in diameter).
Maximum four yard inlet structures are allowed to be interconnected in a drainage system; thereafter a drainage manhole structure is required.
Maximum allowed depth of any yard inlet is six feet.
The developer, as part of the site development, is responsible for the installation and maintenance of erosion and sediment control measures necessary to prevent the transportation of sediments to off-site areas. The subdivision plans shall include an erosion and sediment control plan as part of the submission for review. Erosion and sediment control measures shall be continuously maintained and modified to address field conditions encountered during various phases of construction. The erosion and sediment control plan shall include details showing the intended measures to be employed during construction to meet the requirements of this section. The specific methods and materials employed in the installation and maintenance of erosion control measures shall conform to the New York State Stormwater Management Design Manual and the New York Standards and Specifications for Erosion and Sedimentation Control.
Erosion control measures shall include the following:
The proposed erosion control measures shown on the plans shall be installed prior to the start of construction. Additional erosion control measures may be necessary, based upon field conditions that may develop as construction progresses.
Existing vegetation to remain shall be protected and remain undisturbed.
Clearing and grading shall be scheduled so as to minimize the size of exposed areas and length of time that areas are exposed.
The length and steepness of cleared slopes shall be minimized to reduce runoff velocities and quantities.
Runoff shall be diverted away from clear slopes.
Sediment shall be trapped on site.
Specific methods and materials employed in the installation and maintenance of erosion control measures shall conform to the New York State Guidelines for Urban Erosion and Sediment Control.
Sediment control barriers (silt fence, hay bales or approved equal) shall be installed prior to any grading work along the limits of disturbances and shall be maintained for the duration of the work. No sediment from the site shall be permitted to wash onto adjacent properties or roads.
Graded and stripped areas and stockpiles shall be kept stabilized through the use of temporary seeding or sod as required. Seed mixtures shall be in accordance with the Natural Resources Conservation Service (NRCS) recommendations.[1]
Soils stockpiled on individual lots as a result of excavation for foundations shall be placed to increase the distance these soils must travel to reach the drainage system. Stockpiles shall be covered to reduce sediment loading on the site.
Drainage inlets installed as part of the project shall be protected from sediment buildup through the use of sediment barriers, sediment traps, etc., as required.
Proper maintenance of erosion control measures shall be performed as indicated by the periodic inspection after a rainfall event totaling 0.5 inch of rainfall or greater or during a seven-day inspection program occurring throughout the period of the construction. Maintenance measures include, but are not limited to, cleaning of sediment basins or traps, cleaning and repair of berms and diversions and cleaning and repair of inlet protection devices.
Appropriate means shall be used to control dust during construction.
A stabilized construction entrance/exit shall be maintained to prevent soil and loose debris from being tracked onto adjacent roads. In addition, a water source is to be maintained adjacent to this entrance for the purpose of washing debris from truck tires. The construction entrance shall be maintained until the site is permanently stabilized.
Sediment barriers and other erosion control measures shall remain in place until upland disturbed areas are permanently stabilized.
All slope areas of 1:2 and 1:3 will be protected against erosion during construction, and permanent ground cover shall be such that erosion will be prevented. Necessary measures shall include, but not be limited to, hay bales, silt fence, silt trap/basins, jute mesh, anchored straw mulch, hydroseeding, sod, etc., and shall be maintained for the duration of the construction as well as following the completion of construction until such time that the proposed plantings have become acclimated/established as determined by the Village's representative.
The plans shall also address the following environmental issues the developer shall be responsible for during construction:
Pollution prevention measures to be instituted to prevent litter, construction chemicals, and construction debris from becoming pollutant sources in stormwater discharges from the site.
Description of the method of storing waste materials on site and a description of controls to be employed to reduce pollutants from these materials, including storage practices to minimize exposure of materials to stormwater. Include a spill prevention and response plan.
The installation of a portable sanitary system or a sanitary system established in a field office trailer shall be maintained throughout the term of the project.
Stormwater treatment devices.
For subdivisions where overflow runoff from the property's tributary area enters directly into streams, tidal waters, or roadway drainage systems, such water shall be routed through on-site treatment devices in conformance with the New York State Stormwater Design Manual. A note shall be included on the drainage plan designating maintenance responsibility for the proposed devices.
The Village is willing to consider new technologies proposed for storage. Prior to approval of new technologies, the developer or engineer shall provide manufacturer information for consideration.
Stormwater treatment devices shall include methods to store settleable solids in a manner and a location that will prevent resuspension of previously captured particulates.
Stormwater treatment systems shall be of a hydraulic design that includes flow controls designed and certified by a professional registered engineer using accepted principles of fluid mechanics that raise the water surface inside the tank to a predetermined level in order to prevent the re-entrainment of trapped floating contaminants.
Stormwater treatment systems shall be capable of removing 80% of the net annual total suspended solids (TSS) load based on a fifty-micron particle size. Annual TSS removal efficiency models are to be based on a documented removal efficiency performance from full-scale laboratory tests. Annual TSS removal efficiency models shall only be considered valid if they are corroborated by independent third party field testing. This field testing is to include influent and effluent composite samples from a minimum of 10 storm events at one location.
Stormwater treatment systems and design treatment capacities shall be submitted to the Village for review. The stormwater treatment system shall not resuspend trapped sediments or re-entrain floating contaminants at flow rates up to and including the specified treatment capacity.
Stormwater treatment units shall have flow control (i.e., weir, orifice) structures.
Excavations for dry wells shall extend to a depth where a minimum of six feet of permeable leaching material exists.
Bottoms of dry wells shall be a minimum of two feet above groundwater.
Dry wells are to be installed with a three-foot collar consisting of approvable graded leaching material.
The maximum depth of dry wells and/or diffusion wells is 25 feet. If suitable leaching material does not occur within the 25 feet, the excavation shall extend six feet into suitable material and the hole shall be backfilled with graded material to the proposed bottom elevation of the dry well.
A dry well and/or diffusion well detail shall be provided on the plans.
The minimum spacing between dry wells shall be 10 feet between outside walls.
For condominiums, cooperatives, and townhouses, roof drains shall be directed into dry wells separate from site drainage unless downspouts are to be located on the outside of the building(s). If site conditions prevent the installation of separate dry wells for roof drains, a note is to be placed on the drainage plan stating that the downspouts are to be located on the exterior of the building(s).
Floor drains and trench drains require their own dry wells.
No storage considerations will be allowed for domed sections.
No storage credit is allowed for percolation.
Where dry wells are proposed within individual lots, a note is to be included on the drainage plans stating that the property owner or homeowners' association is responsible for the maintenance of these structures.
Drainage reserve areas (DRAs).
Drainage reserve areas shall be dedicated either to an individual homeowner or to the homeowners' association for the developed property as may be applicable. A note of dedication is to be included on the plans.
Maximum depth of drainage reserve areas is four feet. Where drainage reserve areas extend beyond 30 inches in depth, a five-foot-wide aquatic berm shall be provided at a level two feet below the anticipated high-water mark.
Overflow between drainage reserve areas shall be a minimum of one foot lower than the roadway grade adjacent to it.
No fill is to be placed on the site for the purpose of constructing a drainage reserve area.
Stormwater basins are to be constructed in conformance with the applicable sections of the County of Nassau Department of Public Works 1964 Standard Specifications for the Construction of Highways and Bridges, as subsequently amended, and the County of Nassau Department of Public Works Standard Sheets for the Construction of Highways and Bridges.
The stormwater basin's side slopes are to be graded one on two.
Stormwater basins shall be constructed with two levels. The lower level is to be two feet deeper for the purpose of acting as a sedimentation settling area. The transition slope between the two areas is to be graded one on three between tiers.
Drainage pipes connected to stormwater basins shall outfall into the lower sedimentation area of the basin.
Drainage pipes which outfall into stormwater basins require a headwall conforming to the detail shown in the Nassau County Standard Drawings.
The minimum size pipe to outfall into a stormwater basin is 24 inches.
The maximum gradient for pipes that outfall into stormwater basins is 2%.
Sluiceways are to be constructed in conformance with the Nassau County Department of Public Works (NCDPW) details.
Maintenance access ramps shall be 12 feet wide and constructed at an eight-percent grade from top of berm to bottom of basin. The ramp is to be tilted with the inside edge constructed six inches higher than the elevation of the side slope side opposite it.
Where proposed, the minimum turning radius for ramps shall be 25 feet.
No topsoil is to be placed on side slopes.
A six-foot-high chain link fence with its bottom anchored in a two-foot-deep curb is to be constructed around the perimeter of the basin with a sixteen-foot-wide access gate located near the vicinity of the maintenance ramp, both conforming to Nassau County standards.
A planting screen consisting of approved evergreen trees a minimum of six feet in height shall be planted along the perimeter of the stormwater basin. The trees shall be planted in conformance with Nassau County standard requirements.
Berms (distance between fence and top of slope) shall be 10 feet or 13 feet wide and one foot higher at top of slope than at the fence to prevent erosion.
The fence and plant screening around the basin shall be placed in accordance with the following format:
On street fronts, the fence shall be placed five feet inside the stormwater basin's property line, with an adjacent ten-foot berm. The five feet outside the fence is for planting.
On sides abutting property of others, the fence shall be placed two feet inside the stormwater basin's property line, with an adjacent thirteen-foot berm. The planting is to be located on the inside of the fence.
On sides abutting property of the developer (builder of the stormwater basin), the fence shall be located two feet inside the stormwater basin property, with an adjacent ten-foot berm. A five-foot planting strip shall be located outside the basin's property line with planting located at the center of the strip.
A planting detail is to be included on the plans showing the applicable configuration proposed for the stormwater basins.
No fill is to be placed for the purpose of creating a stormwater basin.
Elevation of anticipated high water is to be shown on the stormwater basin plan.
Access to a landlocked stormwater basin shall be provided through a twenty-foot strip from the street to the basin's entrance and included as part of the basin's property.
A note is to be included on the drainage plan dedicating maintenance responsibility for the retention pond to the homeowners' association.
Retention ponds proposed for aesthetic value without a surrounding fence will require the construction of a five-foot-wide aquatic shelf located one foot below the pond's established water level.
The pond is to be designed to allow the anticipated storage to be renewed as a result of percolation between storm events.
Fill is not to be used for the purpose of creating storage.
The minimum size pipe to outfall into the pond is 24 inches.
Pipes directing flow to dry wells for restoration of storage retention shall be back pitched away from the retention pond at a maximum gradient of 2%.
The plans shall include all details relevant to the construction of the retention pond.
Linear leaching chambers.
Stormwater storage claimed for proposed bedding material shall be substantiated by an approved testing laboratory. The results shall be forwarded to the Village for consideration. The results will be reviewed before permitting claimed storage. A note is to be added to the detail for this unit stating the tested material is required.
Bottom of bedding material shall be a minimum of two feet above groundwater.
A stormwater treatment unit shall be installed to intercept contaminants before dispersing runoff into leaching units.
No consideration will be given to stormwater storage plans proposing an anticipated percolation loss as a substitute for volume storage in the drainage calculations.
§ 400-7 Penalties for offenses. [1]
The violation of any provision of this article shall be punishable as set forth in § 1-8 of this Code.