Model Stormwater Management Ordinance

Model Stormwater Management Ordinance

Section 1 - Short Title


This shall be known as the Model Stormwater Management Ordinance.

Section 2 - Findings of Facts

SECTION 2 - FINDINGS OF FACT. The municipality finds that uncontrolled drainage and runoff associated with land development has a significant impact upon the health, safety and welfare of the community for the following reasons:   A. Stormwater can carry pollutants into receiving waterbodies and degrade water quality.   B. The increase in nutrients in stormwater runoff accelerates eutrophication of receiving waters.   C. Improper design and construction of drainage facilities can increase the velocity of runoff thereby increasing stream bank erosion and sedimentation.   D. Construction requiring land clearing and the alteration of natural topography tends to increase erosion.   E. Siltation of waterbodies resulting from increased erosion decreases the capacity of the waterbodies to hold and transport water, interferes with navigation, and harms flora and fauna.   F. Impervious surfaces increase the volume and rate of stormwater runoff and allow less water to percolate into the soil, thereby decreasing groundwater recharge and stream baseflow.   G. Improperly managed stormwater runoff can increase the incidence of flooding and the level of floods which occur, endangering property and human life.   H. Substantial economic losses can result from these adverse impacts on the waters of the municipality.   I. Many problems can be avoided if sound stormwater runoff management practices are in effect.

Section 3 - Effective Date

SECTION 3 - EFFECTIVE DATE. The effective date of this Ordinance shall be ______________.

Section 4 - Statutory Authority

SECTION 4 - STATUTORY AUTHORITY. Article 9 of the Town Law or Article 7 of the Village Law and Environmental Conservation Law Section 43-0112.

Section 5 - Purpose and Objectives

SECTION 5 - PURPOSE AND OBJECTIVES. The purpose of this Ordinance is to protect and safeguard the general health, safety, and welfare of the public residing in or visiting the municipality by preserving and protecting the quality of the ground and surface waters. This Ordinance has the following specific objectives:   prevent any increase in stormwater runoff from any development in order to reduce flooding, siltation, and streambank erosion,   prevent any increase in pollution caused by stormwater runoff from development which would otherwise degrade the quality of water in Lake George and its tributaries and render it unfit for human consumption, interfere with water based recreation or adversely affect aquatic life, and   prevent any increase in the total annual volume of surface water runoff which flows from any specific site during and following development over that which prevailed prior to development.

Section 6 - Definitions

SECTION 6 - DEFINITIONS. The terms used in this Ordinance or in documents prepared or reviewed under this Ordinance shall have the meanings set forth in Schedule A of this Ordinance.

Section 7 - Jurisdiction

SECTION 7 - JURISDICTION. General Applicability: This Ordinance shall apply to all building, construction, land clearing and subdivision of land within the municipality and within the Lake George Park both public and private except development which is expressly exempt pursuant to Section 8 H. of this Ordinance. Permits and approvals required by this Ordinance may be incorporated into the site plan, land use or zoning approvals issued under separate provisions of the municipality's land use program.

Section 8 - Prohibitions

SECTION 8 - PROHIBITIONS.   A. Except for the activities exempted in paragraph H. of this section, no person shall build, construct, erect, expand, or enlarge any building or structure or place or construct any impervious surface such as pavement, blacktop, macadam, packed earth and crushed stone without first receiving a stormwater management permit from the municipality unless otherwise exempted herein.   B. No person shall create a subdivision of land subject to approval by the municipality until first receiving a stormwater management permit from the municipality for all buildings, structures and impervious surfaces proposed to be created except that the terms of this Ordinance shall not apply to persons engaged in activities for which required municipal permits and approvals were issued prior to the effective date of this Ordinance.   C. No owner of real property shall maintain a condition, which due to a human disturbance of land, vegetative cover or soil, results in the erosion of soil into any water body. The municipality shall notify a property owner of such condition on his property and shall afford a reasonable time period to correct any such condition before a violation shall be deemed to exist.   D. Except for the activities exempted in paragraph H. of this section herein, no person shall operate a land clearing machine such as a back hoe, grader or plow or similar device so as to clear or grade land or otherwise remove vegetative cover or soil or to overlay natural vegetative cover with soil or other materials when such activities involves an area of land greater than 5000 square feet without first having received a permit under this Ordinance.   E. No person shall fail to comply with any provision or requirement of any permit issued pursuant to this Ordinance.   F. No person shall create a condition of flooding, erosion, siltation or ponding resulting from failure to maintain previously approved stormwater control measures where such condition is injurious to the health, welfare or safety of individuals residing in the Park or injurious to any land within the Park. The Municipality shall notify a property owner of such condition on his property and prescribe measures necessary to reestablish effective performance of the approved stormwater control measures. The Municipality shall afford such property owner a reasonable time period in which to correct any such condition, before a violation is deemed to exist.   G. No person shall build, alter or modify a stormwater control measure without first receiving a permit from the Municipality. Such building, alteration and/or modification does not include the ordinary maintenance, cleaning and/or repair of stormwater control measures.   H. The following activities are exempt from the requirements of this Ordinance:   (1) Emergency repairs to any stormwater control measure. (2) Development involving land disturbance and land clearing of less than 5000 square feet which does not result in the creation of new impervious surfaces of more than 1000 square feet.   (3) Any logging and agricultural activity which is consistent with a soil conservation plan approved by the appropriate County Soil and Water Conservation District or a timber management plan prepared or approved by the Department, as applicable.   (4) Any building, construction or land clearing occurring outside the drainage basin of Lake George from which all stormwater discharged from the development site is discharged outside of the basin.   (5) 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.   (6) Construction of an approved wastewater treatment system and construction of a wharf, dock, boathouse, and mooring.

Section 9 - Projects Classification for Stormwater Management

SECTION 9 - PROJECT CLASSIFICATION FOR STORMWATER MANAGEMENT.   A. Minor Projects. The following development activities shall be considered to be minor projects.   (1) Any building, land clearing or development activity affecting less than 15,000 square feet.   (2) Creation of a two-lot, three-lot or four-lot subdivision which may result in the construction of no more than one single-family residential structure and related accessory structures per lot, and will require land clearing or alteration activities of less than 15,000 square feet per lot and less than 15,000 square feet total for any subdivision road.   (3) Any building, alteration, or modification of a stormwater control measure, excluding maintenance, cleaning or repair of such stormwater control measure.   B. Major Projects. Any project not expressly exempted from regulation or defined as a minor project shall be a major project.   (1) The following may be considered to be major projects:   (a) Any part of the activity listed in Section 9. A. (1),(2) or (3) which occurs on (i) soils of high potential for overland or through-soil pollutant transport; (ii) an area with a slope of fifteen percent (15%) or greater when measured in any direction over a distance of one hundred (100) feet from the center of the proposed building site; (iii) or an area with a soil percolation rate slower than sixty (60) minutes per inch.   (b) Any minor project may be treated as a major project if such treatment is desirable due to specific site limitations or constraints, anticipated environmental impacts, or the need or advisability of additional public notice and comment. When determining whether to treat a minor project as a major project, the criteria to be considered shall include, but shall not be limited to, whether the site lies within or substantially contiguous to any of the following: (i) a Critical Environmental Area established pursuant to SEQR; (ii) a wetland; (iii) a stream corridor; (iv) an area of significant habitat for any wildlife or plant species; (v) or an area of particular scenic, historic or natural significance.   The project sponsor of a minor project that will be treated as a major project shall be given a written statement of the reasons for such a determination.

Section 10 - Design Requirements and Performance Standards

A. Minor Projects. The following requirements shall apply to minor projects:
(1) Stormwater shall be managed on-site using stormwater control measures designed to afford optimum protection of ground and surface waters. Stormwater control measures shall be selected by giving preference to the best management practices for pollutant removal and flow attenuation as specified in Schedule C. Stormwater may be calculated in accordance with the methodology for determining stormwater volume and flow rates for major projects found in Schedule B, Part III or, in the alternative, at a flat rate of 1.5 gallons of stormwater for every square foot net increase in impervious area. Net increase is the difference between pre-development and post-development conditions. All water from newly created impervious areas which would otherwise run off the parcel shall be directed to an infiltration device. Location of the infiltration devices shall be determined based upon soil test results.
(2) Stormwater control measures may include, but shall not be limited to, drywells of precast concrete, pits of crushed rock lined with geotextile fabric, and infiltration trenches. Such measures may also include natural and human made landscape features such as depressions, blind ditches, retention ponds, swales and others. Inlets to infiltration devices shall be protected from sediment at all times in order to maintain their capacity.
(3) Infiltration devices shall not be installed up gradient within twenty (20) feet of the subsurface treatment system of a wastewater treatment system. Infiltration devices for roadways, parking lots, and other areas subject to vehicle traffic shall not be installed within 100 feet of any water well, wetland or water body.
(4) Infiltration devices and buildings shall be designed to maintain maximum attainable horizontal distance separation from wells, water bodies and wetlands. Pumping stormwater shall not be permitted.
(5) The bottom of any infiltration device shall be a minimum of two feet above seasonal high ground water mark and two feet above bedrock.
(6) Temporary erosion controls shall be required to prevent siltation of water bodies during construction.
(7) Stormwater control measures proposed to be installed at locations with slope > 15% before grading, soil percolation rate slower than 60 minuets per inch or which require placement of fill to meet horizontal distance separations specified in this subpart shall be designed by a licensed professional engineer, architect or exempt land surveyor.
B. Major Projects.
(1) Stormwater volumes and rates of flow shall be calculated using the methods specified in Schedule B Part III.
(2) Design Requirements for Stormwater Control Measures.
(a) Stormwater control measures shall be designed so that there will be no increase in runoff volume from a ten-year frequency/twenty-four hour duration storm event following development over the pre-development volume.
(b) For storm events exceeding the 10-year design storm, the stormwater control measures shall function to attenuate peak runoff flow rates for a 25-year frequency storm to be equal to or less than predevelopment flow rates. For development greater than five (5) acres, consistent with New York State Guidelines, stormwater control measures shall function to attenuate peak runoff flow rates for a 100-year storm to be equal to or less than predevelopment flow rates. Attenuation of the 100-year storm is intended to reduce the rate of runoff from development to prevent expansion of the 100-year flood plain so as to alleviate flooding of improved properties and roadways. The minimum requirement for peak flow attenuation can be waived for the 100-year storm event where it can be proven that downstream flooding is not a concern, such as where excess stormwater runoff is discharged to Lake George or to a regional stormwater facility designed to handle additional volume and peak discharge. The cumulative effect of all proposed development projects within the watershed should be considered in making this determination. Rainfall intensity curves for Lake George, New York shall be used in the design of the stormwater control measures. These curves are annexed to this Ordinance as Schedule D entitled Rainfall Intensity Curves. Additionally, for development greater than five (5) acres, coverage is required under a State Pollutant Discharge Elimination System (SPDES) General Stormwater Permit administered by the Department of Environmental Conservation.
(c) Infiltration devices shall be designed such that the bottom of the system will be a minimum of two feet above the seasonal high groundwater level to be realized following development. Where compliance with this requirement would prevent compliance with subparagraph (e) of this Section, compliance with this requirement may be waived. This provision shall not apply to wet ponds and similar stormwater control measures which are designed to be built in the saturated soil zone.
(d) Infiltration devices for major projects shall be located a minimum of one hundred (100) feet from Lake George and any downgradient drinking water supply, lake, river, protected stream, waterwell, pond, wetland; a separation of more than one hundred (100) feet may be required in cases where contamination of the water supply is possible due to highly permeable soils, shallow groundwater and similar situations. The separation distance shall be a minimum of fifty (50) feet from upgradient water supplies. Designs shall mitigate adverse effects that groundwater recharge will have on adjacent wells, water supplies, wastewater treatment systems, buildings, roadways, properties, and stormwater control measures. Stormwater recharge areas shall be located a minimum of one hundred (100) feet from the subsurface treatment system of a wastewater treatment system unless it is demonstrated that a lesser separation will not adversely affect the functioning of such leach fields.
(e) Infiltration devices shall be designed to extend a minimum of ten percent of the infiltration surface area below the prevailing frost depth or four feet (whichever is greater) in order to provide infiltration during winter months.
(f) Infiltration devices shall be designed based on the infiltration capacity of the soils present at the project site. Soil evaluation methods shall be in accordance with Schedule B, Part IV, Soil Evaluation Methods.
(3) Additional Requirements for Major Projects.
(a) Stormwater control measures shall be used in the following order of preference: (i) infiltration devices; (ii) artificial wetlands and acceptable natural treatment systems; (iii) flow attenuation by use of open vegetated swales and depressions; (iv) stormwater detention. Stormwater control measures shall be selected by giving preference to the best management practice for pollutant removal and flow attenuation as indicated in Schedule C.
(b) All stormwater control measures shall be designed to completely drain to return to design levels in accordance with the following: infiltration basin 5 days; infiltration trench 15 days; dry well 15 days; porus pavement 2 days; vegetation depression 1 day.
(c) Pretreatment devices such as sediment traps, detention/stilling basins, filter strips, grassy swales, or oil/water separators shall be provided for runoff from paved areas or other areas subject to human-induced pollution including grease and oils, fertilizers, chemicals, road salt, sediments, organic materials and settleable solids, which shall be sufficient to remove pollutants from the runoff.
(d) Stormwater control measures shall, at a minimum, incorporate the best available pollutant removal technology, which shall mean that which constitutes appropriate and cost effective means for removing pollutants from runoff so that the resulting treated stormwater will not degrade the water quality of any water body.
(e) Stormwater control measures shall be designed to preserve and maintain the base flow in all streams passing through, adjoining or receiving runoff from the site.
(f) For development or redevelopment occurring on a site where development has previously occurred, the applicant shall be required to prepare concept plans and to develop construction estimates for stormwater control measures to control existing stormwater discharges from the site in accordance with the standards of this Ordinance to the maximum extent practicable. At a minimum the control measures shall include those reasonable and necessary to infiltrate the runoff from the first one-half inch of precipitation from any storm event for all areas within the site which have been previously developed. The phased implementation of such stormwater control measures for previously developed areas may be authorized.
C. General Requirements For Major and Minor Projects. The following requirements shall apply to major and minor projects:
(1) Stormwater control measures shall include such other measures as are deemed necessary to prevent any increase in pollution caused by stormwater runoff from development which would otherwise degrade the quality of water in Lake George and its tributaries, render it unfit for human consumption, interfere with water-based recreation or adversely affect aquatic life.
(2) Emergency overflow provisions shall be made as necessary to prevent erosion, flooding, and damage to structures, roads and stormwater control measures.
(3) Stormwater control measures shall be designed to minimize adverse impacts to water bodies, minimize disturbance of water bodies, minimize land clearing, minimize the creation of impervious surfaces, and to maximize preservation of natural vegetation and existing contours.
(4) Development which involves the creation of areas subject to intensive landscape maintenance such as: golf courses, public parks and botanical gardens, shall require that a pest control and fertilizer management plan shall be prepared and included with the permit application.



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