[HISTORY: Adopted by the Town Board of the Town of Williamson 11-10-2003 by L.L. No. 3-2003. Amendments noted where applicable.]
It is the purpose and intent of this chapter to protect the Town of Williamson and its residents from the adverse effects of stormwater runoff caused by the modification of existing drainage systems during construction, reconstruction, development or improvement on one or more parcels of land, or by modification for any other purpose.
The adverse effects include but are not limited to the following:
Increased rate, quantity, velocity of stone drainage, soil movement or erosion, sediment accumulation and flows caused by but not limited to:
A decrease in area of soil able to absorb water, due to construction or reconstruction of streets, buildings and parking lots.
Change in volume, velocity and duration of water concentration caused by altering the steepness, distance and surface roughness.
The obstruction of stream and channel flow by construction or reconstruction, backfilling, excavating and refuse disposal.
The removal of surface vegetation prior to or during construction and development without proper precautions in place.
As used in this chapter, the following terms have the meanings indicated:
- AGRICULTURAL OPERATIONS
- The activities associated with producing crops or raising livestock.
- APPROVED GRADING, EROSION AND SEDIMENT CONTROL PLAN
- A plan, approved by the subdivision of government as required by law, that covers grading, erosion and sediment control.
- Water-bearing rock or soil strata.
- The bed or lowest point of a watercourse.
- CLOSED DRAINAGE
- A network of conduits, pipes, culvers and appurtenant structures constructed to convey the runoff of natural surface waters.
- The County of Wayne.
- The holding of natural surface water during and following a rainfall event, or during snow melt conditions, in an area planned for such use, in such a way that the addition of the detained water to downstream drainageways or natural watercourses can be achieved in a controlled manner, usually by means of a throttling facility such as a culvert or weir structure.
- DETENTION AREA
- The temporary body of water created by planned detention which makes use of natural water collection areas, or areas which tend to collect surface water due to man-made terrain features such as limited-flow culverts, restricted outlets, etc.
- DETENTION STRUCTURE
- A man-made construction which creates a detention pond by limiting flow rates away from a natural collection area or which adds to the detention capacity of such an area.
- The actual owner or owners of the land and/or person, firm or corporation which develops or uses land within the Town in such a manner that it in any way affects the storm or surface water drainage characteristics of the property developed or used. The term “developer” shall include municipal, charitable and educational corporations, institutions, associations and governmental agencies.
- Any improved land use, including residential, commercial, industrial, institutional or recreational; includes development of raw land as well as additions or alterations to presently developed land.
- A narrow excavation having steep sides, used to drain or irrigate property.
- The gravitational movement of water from its place of origin via surface runoff within or outside developed channels or via subsurface underfow.
- DRAINAGE BASIN
- The area drained by a watercourse, in this chapter used interchangeably with “watershed.”
- DRAINAGE COUNCIL
- A committee appointed by the Town Board.
- DRAINAGE EASEMENT
- A permanent and/or temporary right-of-way granted by the owner to the Town providing unhindered access to the banks and channels of streams and drainage systems.
- DRAINAGE SYSTEM
- A network consisting of any combination or type of open channels and enclosed artificial facilities and/or retention or detention facilities employed to convey or control the runoff of natural surface waters.
- ENCROACHMENT LIMIT
- The boundary of a maintenance way easement adjacent to a portion of a drainage system within which no building or structure shall be erected and within which no trees, bushes or other vegetation shall be planted or allowed to grow which will interfere with the maintenance of the drainage channel, unless otherwise allowed, as in an agricultural exclusion.
- ENCROACHMENT OFFICER
- The agent designated by the Town Board to monitor and enforce the encroachment limits as defined above.
- The removal of sand, gravel, soil, including topsoil or other natural deposits, by stripping, digging or any other means.
- The depositing of natural or artificial material that raises the existing grade of land or modifies the surfaces of water bodies.
- The area of normally dry terrain that becomes covered with water during and after local or up-stream rainstorms and/or ice melt conditions. The floodplain for a specific watercourse may be defined in terms of the severity of the precipitation event, which causes the flooding. Floodplains may be determined from maps prepared by the U.S. Army Corps of Engineers, by the Federal Flood Insurance Administration (FIA) or as a result of special engineering studies. Changes in the natural drainage system may change the locations of the floodplain limits.
- In general, the area through which, or over which, floodwaters flow at specific levels of runoff severity. The FIA has a special definition for insurance purposes.
- FLOW RATE
- The quantity of water that moves past a given point in a specified increment of time, usually measured in cubic feet per second (cfs).
- The alteration of the existing grade of land through excavation or filling.
- OPEN DRAINAGE
- A network of natural streams, creeks, constructed channels and ditches or swales employed to convey the flows of natural surface waters.
- RETENTION FACILITY
- An area or structure without an outlet or with a controllable outlet, intended to collect and store surface water during and after precipitation to prevent excessive downstream flows. A retention facility has a normal low water pool above, which is designed freeboard to contain storm flows.
- Rocks or stones placed on soil to prevent erosion from precipitation or moving water.
- SEDIMENTATION; SILTATION
- The deposition of soil carried by floodwaters.
- The removal of overburden, topsoil, soil, vegetation or other natural material from land.
- SURFACE WATER
- That portion of natural precipitation which moves across the land surface, as sheet flow or as channelized flow to permanent watercourses.
- A shallow, relatively wide drainage channel of area, with flatter side slopes than a ditch, usually covered with grass or other natural vegetation.
- TEMPORARY COVER
- Vegetative material or stable mulch.
- The natural surface layer of an undisturbed area of terrain, usually darker than the underlying layer, ranging in organic matter content from 2% to 50% and which ranges in texture from loamy fine sand to clay.
- The Town of Williamson.
- A stream channel, swale, ditch, etc., contributing flow to a larger stream or body of water.
- The speed of water, usually related in feet per second (fps).
- A quantity of water, usually related in cubic feet (cf).
- A stream of water. It may be natural or man-made and may flow seasonally or year round.
- The area drainaged by a watercourse, usually divided by a ridge or crest line of natural topography but sometimes by manmade constructions. Same as “drainage basin.”
- WATER TABLE
- The level below which the soil is saturated with water.
- Land and submerged lands commonly called “swamps” or “marshes” which support aquatic or semi-aquatic vegetation, plants or brush.
The design and construction of drainage systems shall be such that watercourses traversing the development and natural water emanating from within the development will be carried through and off the development without injury to improvements, building sites or buildings existing or to be installed downstream within or adjacent to the development. Drainage water entering the development shall be received and discharged at locations and in the manner that existed prior to construction of the drainage facilities within the development unless special provisions are made to handle it otherwise. The design of drainage facilities within the development shall be such that they will conform to the ultimate drainage requirements of the land within the development watershed. The discharged flow at the downstream area of the development shall be conducted in drainage facilities so that the flow effects shall be restored to pre-development conditions prior to leaving the development area or reasonably distant therefrom unless approval is given by the Town to do otherwise.
Natural drainage patterns shall be employed in preference to rechanneling streams or watercourses. In no case shall work be performed which directly or indirectly affects natural drainage patterns without the granting of approval by the Town, county and state agencies having jurisdiction.
No chemicals, fuels, lubricants, or other pollutants shall be disposed of or deposited into any streams, drainage or water supply systems.
Fill and refuse shall not be disposed of or deposited upon or immediately adjacent to any wetland, floodplain or drainageway, except where otherwise permitted.
Man-made structures shall be placed so as not to block or restrict, in any manner, natural drainage patterns, except where otherwise permitted.
Where land excavations or filling has been permitted, provision shall be made for the safe conduct of surface water across the face of the slope, for subsurface drainage as necessary and to prevent materials from washing across or upon the property of another.
Ponds and retention or detention facilities shall be employed as required by the Town.
All drainage systems and stormwater sewer capacity shall be designed to handle the anticipated flows from the entire upstream drainage basin when fully developed according to existing zoning, and these anticipated flows shall be determined by the Town unless approval is given by the Town to size otherwise.
In order to expedite surface drainage, a minimum grade of 0.5% shall be employed on all newly finished swales, unless otherwise required.
Sedimentation basins shall be employed during or after construction as required by the Town to prevent siltation or turbidity in watercourses or drainage systems.
Surface waters and drainage, where identified as being significant sources of groundwater replenishment and where such resources are being utilized as a potable water supply, shall not be revised or altered except by approval of the Town.
Any of the above requirements may be waived by presentation of sufficient evidence as determined by the Town Board.
Except as hereinafter provided, it shall be unlawful for any person, firm, entity or corporation to:
Modify the topography or surface qualities of any area greater than 20,000 square feet so that the water retention or discharge characteristics of the area are modified, unless the action has been approved by the Town Board through its Drainage Council. Recognized agricultural procedures in active agriculture areas as defined by New York State Division of Agriculture and Markets are exempted from the regulations herein defined.
Place, deposit or permit to be placed or deposited any debris, fill, sand, stone or other solid materials of any kind or nature or construction of any kind into or across any watercourse, including culverts, pipes, or other drainage systems that may cause the obstruction or alteration of flow through the area.
Fill, obstruct, dam, divert or otherwise change or alter the natural or artificial flow of waters or drainage or the intensity or quantity of flow through any stream, ditch, pipe, culvert, watercourse or other improvement or drainage system.
The drainage channels for watercourses numerically identified in the Town of Williamson Storm Drainage Study of 2002 (or any updates) shall be provided to accommodate not less than the minimum flows indicated in that drainage study or the latest similar study accepted by the Town. These values shall be independently verified by the developer or landowner using hydrologic technology described in § 81-5B, and the hydrologic analysis thereof shall become a part of the supporting data of the proposed drainage plans.
The capacity of the channel that will occupy the ultimate drainage easement within the development shall be based upon both the existing degree and anticipated rate of urbanization within the development watershed and the type of development possible under the Zoning Ordinance of the Town, as the same may be modified from time to time. Whenever a development may be located within a watershed undergoing initial stages of urban development, the proposed drainage system shall adequately pass the flows that would develop from continued urbanization within the useful life of the proposed channel improvement or system. Proposed drainage systems within developments located in watersheds that may be in the advanced stages of urbanization shall be designed and constructed to pass the project designs flow determined for the ultimate urbanization of the tributary watershed. Where this is not practical, storage basins may be provided to increase the capacity of the drainage systems and control flows to downstream drainage systems and/or structures such that the capacity of the latter will not be exceeded.
These storage basins may be two types, as follows:
A detention basin, drained by gravity through a control-sized pipe located at the downstream end of the basin.
A retention basin utilizing a normal water level, completely drained usually by pumping. Usually a low water level will remain in the basin with freeboard designed to accommodate storm flows.
Storage basins are sized to accept excessive flow over and above the capacity of downstream drainage facilities. They may be used to change, in a beneficial way, flows through a proposed development or from a proposed development.
For undeveloped areas of the tributary watershed, the surface permeability classification shall be based upon the Town of Williamson Zoning Maps and correlated with projected land uses developed by the Town Master Plan. Wherever a development watershed contains excessive permanent land uses, such as railroads, public parks, cemeteries and parkways, such factors may additionally be considered in determining an appropriate coefficient of runoff.
Drainage systems classed as “minor” shall be checked by engineering computations to pass the flow requirements of the next higher design level.
Prospective developers and their engineers should consult the “Guidelines for Erosion and Sediment Control in Urban Areas of New York State” by the United States Department of Agriculture, Soil Conservation Service as a publication that contains many resources for handling and controlling stormwater.
The hydraulic design of development drainage systems shall be in accordance with modern standard procedures and shall conform to the latest professional manuals dealing with the many considerations required for a comprehensive drainage system.
The hydraulic design of all drainage systems shall conform in basic details to the American Society of Civil Engineers Manual of Engineering Practice No. 37 and such other applicable manuals as would supplement the ASCE Manual or integrate advanced and proven hydraulic principles and basic assumptions. Open and closed drainage systems shall be designed to provide complete drainage for all elements within the development and shall include all appurtenances essential for the adequate performance thereof. The size of conduits shall be selected at grades which produce a minimum velocity of three feet per second when flowing full.
A development-grading plan indicating a contour interval suitable for the map scale shall be provided to show detailed comprehensive and efficient surface drainage for all lots within and immediately adjacent to the development.
Structural. Catch basins, manholes, inlet structures and other appurtenances placed within the development shall be designed to conform to standard specifications approved by the Town.
Channels. The minimum center-line radius of constructed curved channels shall be at least three times the bottom width of the channel for subcritical flow. The minimum bottom width of constructed channels shall be four feet. The creation of excessive numbers of curves in open channels shall be avoided by reason of the increase in friction loss and the potential erosion due to spiral flow. Outer bank protection, especially at the downstream end of the curve and, to a lesser degree, on the inner bank at the beginning of the curve, may be required by the Town. Earth channels constructed within the development shall have side slopes of one on four or flatter, unless otherwise approved by the Town.
Enclosed conduits. Except for adequate natural watercourses, all storm drainage within the development which is capable of being transmitted in a forty-eight-inch diameter pipe shall be carried in an enclosed conduit. If it is deemed in the public interest by the Town, this size may be varied, either increased or decreased, according to topographic conditions or an economic analysis of the cost of the conduit against an equivalent open channel, including the occupied land value. The minimum conduit size shall be 12 inches in diameter. Manholes shall be provided at all changes in grade and direction. Spacing of manholes and minimum cover of conduits shall conform to the standard practice endorsed by the American Society of Civil Engineers. Inverted siphons shall not be permitted.
All preexisting obstructions or deposits or alterations or diversions of the natural flow of water or the intensity or quality of flow through any watercourse or drainage system which cause the inundation of real property, buildings or other premises or, in the opinion of the Town Board through its Drainage Council, constitute an undue burden upon the drainage system or hamper the proper present or future course of development of the drainage system, or, in the opinion of the Town Board through its Drainage Council, presently constitute or in the reasonably foreseeable future will constitute a danger or hazard to the well-being, safety or general welfare of the residents of the Town or any property located therein, may be removed or corrected by the Town upon 10 days' notice by the Town. The Town will endeavor to replace improvements necessary for essential use of the property, such as driveway culverts.
Easements for enclosed conduits and appurtenances. An easement not less than 20 feet in width, sufficient to contain the enclosed conduit and appurtenances thereof and to provide working space for personnel and equipment for the servicing thereof, shall be indicated on the map of the development and designated as follows: “Drainage Easement to the Town of Williamson.” Drainage easements for enclosed conduits shall, insofar as possible, be placed along or adjacent to lot boundary lines in a parallel and straight alignment.
Natural and/or man-made watercourses which traverse a development shall be preserved by an easement of sufficient width, including overbanks, which will adequately pass the project design flow. The gross allowable depth of flow shall not create a flood hazard to existing or proposed development and improvements. The channel and over bank widths, together with a continuous maintenance way as specified by the Town, shall constitute the floodway encroachment limits. Wherever such natural watercourses are endowed with significant natural beauty and have adequate capacity or have been determined to have value for fish and wildlife, the developer may dedicate widths in addition to those required above on the map of the development with the following designation: “Drainage Easement to the Town of Williamson.”
The developer shall submit detailed drainage plans with a report containing sufficient data for the Town to check the feasibility of the drainage system as proposed by the developer. The following data shall be included:
The plan and profile of all drainage systems shall be provided.
Sizes and types of drainage improvements, including special structures, typical sections, easement, etc.
When required, supporting calculations for upstream and downstream channel capacities as they affect water surface levels and backwaters within or adjacent to the development. Such calculations shall be supported by such additional survey information as may be required to determine a profile and cross section of the upstream and downstream channel reaches of the development under construction.
A detailed development-grading plan prepared to suitable contour intervals with grading details to indicate proposed street grades and elevations, watercourse grades and elevations, building site elevations and surface elevations at critical points throughout the development.
In certain cases, the Town may waive the requirement for detailed drainage plans of one- or two-lot parcels when the work proposed involves only minor modifications or alterations to the drainage system. In the event that detailed plans are waived, the developer shall be required to submit a drainage plan containing sufficient data for the Town to check the feasibility of the drainage system as proposed by the developer.
The final construction plans for drainage within the development shall conform to the provisions of the Town of Williamson Planning, Zoning Board or Master Plan regulations, subsequent amendments thereto and any particular conditions as required by the Town in approving the proposed plans and supporting data thereof. The construction plans for the drainage requirements shall be approved by the Town prior to the construction of any drainage facilities within the development.
The plans shall bear the certification of a licensed professional engineer as evidence of the professional responsibility for the drainage planning within the development and shall contain the following information:
A vicinity sketch and boundary line survey of the site on which the work is to be performed.
Location of any existing buildings, structures, utilities, sewers, water storm drains and natural features on the site where the work is to be performed.
Location of any building or structure on land of adjacent property owners within a minimum of 50 feet of the site and further as necessary to show directly affected parcels.
Spot elevations and existing and proposed contours, dimensioned extent of all work proposed to be done and existing shrub masses and trees to be accurately located and labeled.
A computation of the volume of excavation and fill involved and the quality of fill.
Detailed plans of all drainage provisions, retaining walls, cribbing, vegetative practices, erosion and sediment control measures; excavations or ponding areas, outfall control devices, outlet weirs, etc., and other protective devices to be constructed in connection with or as a part of the proposed work; together with a map showing the drainage area of land tributary to the site and estimated cubic-foot-per-second runoff of the area served by any drain, computed in accordance with current Town development criteria.
A timing schedule and sequence indicating the anticipated starting and completion dates of the development sequence, stripping and/or clearing, rough grading and construction, final grading and vegetative establishment and maintenance and the time of exposure of each area prior to the completion of effective erosion and sediment control measures and any traffic or noise problems.
The depth to bedrock as determined during site evaluation.
The depth to water table as determined during site evaluation.
The types of soils encountered as determined during the site evaluation.
All drainage construction shall be subject to inspection by the Town. Any field changes which affect the intent of these provisions shall have the prior approval of the Town.
In certain cases the Town may waive the requirement for detailed construction plans and certification of plans by a licensed professional engineer on parcels when the work proposed involves only minor modifications or alterations to the drainage system. In the event that detailed plans are waived, the developer shall be required to submit construction plans containing sufficient data for the Town to check the feasibility and adequacy of the drainage system as proposed by the developer.
Any person, firm, corporation or entity found to be violating any of the provision of this chapter shall be served with a written notice by the Town stating the nature of the violation and providing a thirty-day time limit for the satisfactory correction thereof, subject to appeal to the Town Board within 10 days.
Any person, firm, corporation or entity who shall continue any violation beyond the time limit provided for in Subsection A shall be guilty as follows:
For a first offense or violation, punishable by a fine of not more than $250 or by imprisonment not to exceed 15 days, or by both fine and imprisonment; and
For a second offense occurring within one year after the conviction of a first offense of a Class A misdemeanor, punishable by a fine of not more than $1,000 or by imprisonment not to exceed one year, or both fine and imprisonment; and
In addition to the foregoing, by a penalty of $500 to be recovered by the Town of Williamson in civil action.
Each and every day that a violation of any of the provisions of this chapter exists shall constitute a separate violation.
Any person, firm, corporation or entity violating any of the provisions of this chapter shall become liable to the Town for any expense or loss or damage occasioned by the Town by reason of such violation. The Town shall have the right to assess all such expenses against the land on which the violation occurred and to bring legal action to recover such expenses.
The approval of plans for proposed drainage systems and flood hazard prevention requirements shall not constitute a representation, guaranty or warranty of any kind or nature by the Town of Williamson or by an officer or employee thereof of the safety, operation, adequacy or intent of the proposed facilities and shall create no liability upon or cause for action against such public body, officer or employee for any damage that may result from construction pursuant thereto.