The intent of this chapter is to reduce the amount of post-construction stormwater and associated pollutants reaching waters of the state. Use of this chapter by municipalities will foster the consistent statewide application of post-construction performance standards for new development and redevelopment contained in Ch. NR 151, Subchs. III and IV, Wis. Adm. Code.
A.
Where not otherwise limited by law, this chapter applies after final stabilization to a site of land disturbing construction activity meeting any of the criteria in this subsection, unless the site is otherwise exempt under Subsection B:
(1)
A post-development construction site that had 1/2 acre or more of land disturbing construction activity after March 10, 2003.
B.
Exemptions. A site that meets any of the following criteria is exempt from the requirements of this chapter:
(1)
A redevelopment post-construction site with no increase in exposed parking lots or roads.
(2)
A post-construction site with less than 10% connected imperviousness based on complete development of the post-construction site, provided the cumulative area of all parking lots and rooftops is less than 1/2 acre.
(3)
Nonpoint discharges from agricultural facilities and practices.
(4)
Nonpoint discharges from silviculture activities.
(5)
Routine maintenance for project sites under five acres of land disturbance if performed to maintain the original line and grade, hydraulic capacity or original purpose of the facility.
(6)
Underground utility construction such as water, sewer and fiber optic lines. This exemption does not apply to the construction of any aboveground structures associated with utility construction (such as buildings, pavement, including gravel base course, etc.).
(7)
Land disturbing construction activity that includes the construction of a building and is otherwise regulated by the Wisconsin Department of Safety and Professional Services under § SPS 321.125 (Uniform Dwelling Code), Wis. Adm. Code.
C.
Notwithstanding the applicability requirements in Subsection A, this chapter applies to post-construction sites of any size that, in the opinion of the Director, are likely to result in runoff that exceeds the safe capacity of the existing drainage facilities or receiving body of water, that causes undue channel erosion, that increases water pollution by scouring or the transportation of particulate matter or that endangers property or public safety.
A.
Water quality. The following methods shall be used in designing the water quality, peak flow reduction and infiltration components of stormwater practices needed to meet the water quality standards of this chapter:
(1)
Technical standards identified, developed or disseminated by the Department under Ch. NR 151, Subch. V, Wis. Adm. Code. SLAMM is the recognized method to evaluate stormwater quality.
(2)
Where technical standards have not been identified or developed by the Department, other technical standards may be used provided that the methods have been approved by the Director.
Unless otherwise identified in this chapter, all post-construction land development, redevelopment, and infill development activities subject to this chapter shall establish on-site management practices that address peak flow rate discharges from the site, the quality of the discharged stormwater, and the volume of the discharged stormwater. The responsible party shall implement a post-construction stormwater management plan that incorporates the requirements of §§ 330-23 through 330-26. A written stormwater management plan in accordance with § 330-28 shall be developed and implemented for each post-construction site. The plan required under this section shall include the following:
A.
General.
(2)
A final subdivision plat, certified survey map or development plan shall not be approved until the developer shall submit plans, profiles and specifications as specified in Chapter 408 and this chapter which have been prepared by a registered professional engineer and approved or modified by the Director, upon the recommendation of the Village Engineer.
(3)
Lots shall be designed to provide positive drainage away from all buildings. Individual lot drainage shall be coordinated with the general storm drainage pattern for the area. Drainage shall be designed so as to avoid concentration of storm drainage water from each lot to adjacent lots.
(4)
Public drainage easements are required when drainage is conveyed across more than two lots.
(5)
The Board shall not approve any development plan which does not provide adequate means for stormwater or floodwater runoff. Any stormwater drainage system will be separate and independent of any sanitary sewer system.
(6)
Storm sewers shall be designed in accordance with all governmental regulations, and a copy of design computations for engineering capacities shall accompany plans submitted by the developer for the proposed improvements. When calculations indicate that curb capacities are exceeded at a point, basins shall be used to detain flow at that point and no further allowance shall be made for flow beyond that point.
B.
Total suspended solids. Best management practices shall be designed, installed and maintained to control total suspended solids carried in runoff from the post-construction site as follows:
(1)
For new development, by design, reduce to the maximum extent practicable the total suspended solids load by 80%, based on the average annual rainfall, as compared to no runoff management controls. No person shall be required to exceed an eighty-percent total suspended solids reduction to meet the requirements of this subsection.
(2)
For redevelopment.
(a)
Sites less than five acres. By design, reduce to the maximum extent practicable the total suspended solids load by 40%, based on the average annual rainfall, as compared to no runoff management controls. No person shall be required to exceed a forty-percent total suspended solids reduction to meet the requirements of this subsection.
(b)
Sites greater than five acres. By design, reduce to the maximum extent practicable the total suspended solids load by 80%, based on the average annual rainfall, as compared to no runoff management controls. No person shall be required to exceed an eighty-percent total suspended solids reduction to meet the requirements of this subsection.
(3)
For infill development that occurs within 10 years after the effective date of this chapter.
(a)
Sites less than five acres. By design, reduce to the maximum extent practicable the total suspended solids load by 40%, based on the average annual rainfall, as compared to no runoff management controls. No person shall be required to exceed a forty-percent total suspended solids reduction to meet the requirements of this subsection.
(b)
Sites greater than five acres. By design, reduce to the maximum extent practicable the total suspended solids load by 80%, based on the average annual rainfall, as compared to no runoff management controls. No person shall be required to exceed an eighty-percent total suspended solids reduction to meet the requirements of this subsection.
(4)
For infill development that occurs 10 or more years after the effective date of this chapter. By design, reduce to the maximum extent practicable the total suspended solids load by 80%, based on an average annual rainfall, as compared to no runoff management controls. No person shall be required to exceed an eighty-percent total suspended solids reduction to meet the requirements of this subsection.
(5)
Notwithstanding Subsection B(1) through (4) above, if the design cannot achieve the applicable total suspended solids reduction specified, the stormwater management plan shall include a written and site-specific explanation why that level of reduction is not attained and the total suspended solids load shall be reduced to the maximum extent practicable. The Committee and Director shall review and approve or reject the explanation.
(6)
Flow paths and outlets. Water discharging to best management practices shall be directed over permanent vegetative cover unless otherwise approved by the Director. Outlet structures for best management practices shall be located opposite from the inlet.
C.
Peak discharge.
(1)
Two- and five-year rainfall events. By design, BMPs shall be employed to maintain or reduce the post-development peak runoff discharge rates, to the maximum extent practicable, as compared to predevelopment peak runoff discharge rates respectively for the two- and five-year, twenty-four-hour design storm events applicable to the post-construction site.
(2)
Ten-year rainfall event. By design, BMPs shall be employed to maintain or reduce the ten-year post-development peak runoff discharge rates, to the maximum extent practicable, as compared to two-year predevelopment peak runoff discharge rates for the twenty-four-hour design storm events applicable to the post-construction site.
(3)
One-hundred-year rainfall event. By design, on-site BMPs shall be improved to convey the one-hundred-year rainfall event through the site without damage to persons or property. Outfall structures shall be improved to be stable when conveying drainage from the one-hundred-year rainfall event.
(5)
Predevelopment conditions shall assume "good hydrologic conditions" for appropriate land covers as identified in TR-55 or an equivalent methodology. The meanings of "hydrologic soil group" and "runoff curve number" are as determined in TR-55.
(a)
Hydrologic parameters shall be selected based on soil groups using the Sheboygan County Soil Survey (United States Soil Conservation Service/Natural Resources Conservation Service), field observations and supporting laboratory analysis.
(b)
When predevelopment land cover is cropland, rather than using TR-55 values for cropland, the runoff curve numbers in Table 330-23A shall be used.
Table 330-23A Maximum Predevelopment Runoff Curve Numbers | |||||
|---|---|---|---|---|---|
Hydrologic soil group | A | B | C | D | |
Runoff curve number cropland areas | 66 | 74 | 80 | 82 | |
Runoff curve number meadow/grass areas | 60* | 60* | 71 | 78 | |
NOTES: | ||
* | Sixty is the minimum due to runoff on frozen soils. | |
(c)
The runoff curve numbers (RCN) for land which was cropland within the last 10 years will be based on a typical dairy farm crop rotation (CCOHHH). Land which has not been used for crops within the last 10 years should use the parameters that describe the actual conditions; however RCN may not be larger than those for cropland.
(6)
Subsection C of this section does not apply to any of the following:
(a)
A post-construction site where the change in hydrology due to development does not increase the existing surface water elevation at any point within the downstream receiving water by more than 0.01 of a foot for the two-year, twenty-four-hour storm event.
(b)
Riparian properties. Lands immediately adjacent to and discharging directly to the Pigeon River (and its tributaries) without flowing over or through a municipally owned separate storm sewer or stormwater conveyance system.
D.
Conveyance.
(1)
General.
(a)
All stormwater conveyance systems within proposed developments shall be improved to completely contain peak flow rates as described below. Calculations for determining peak flows for conveyance system sizing shall be based on the existing and/or future land use conditions for site areas (whichever result in the highest peak flows) and the future proposed land use conditions for the on-site areas.
(b)
The developer shall construct all the storm drainage facilities identified on the construction documents required in this subsection necessary to serve and resulting from both the current development phase that is being improved and adjoining properties.
(2)
Easements.
(b)
Where a development is traversed by a watercourse, drainageway, channel or stream:
[1]
A drainage easement shall be dedicated that includes the lines and route of such watercourse. The easement width shall accommodate construction, the drainageway and maintenance functions as may be necessary to comply with this chapter and Chapter 408;
[2]
The watercourse, drainageway, channel or stream may be relocated to provide drainage and accommodate maintenance within existing public rights-of-ways and easements. A drainage easement shall be dedicated to the Village to include the lines and route of such watercourse. The easement width shall accommodate construction, the drainageway and maintenance functions as may be necessary to comply with this chapter and Chapter 408; or
[3]
Wherever possible, drainage shall be maintained in an easement using an open channel with landscaped banks and capacity to accommodate the flow rates and volumes.
(c)
In all cases, such easements shall be of a minimum width established at the high-water mark and include dry land maintenance access, or, in the absence of such specification, the minimum easement width is 20 feet.
(3)
Roadways.
(a)
Street and alley drainage. All streets and alleys shall be constructed with a storm drainage system. The street storm system shall serve as the minor drainage system and shall be designed to convey drainage from the street, adjacent land and building runoff. Stormwater shall not be permitted to enter the sanitary sewer system.
(b)
Off-street drainage. The design of the off-street major drainage system shall include the entire watershed affecting the development. The system shall extend to a watercourse or drainageway that has capacity to accommodate the storm drainage. When the drainage system is outside of the street right-of-way, the developer shall dedicate an easement to the Village pursuant to Subsection D(2) to provide for the future system maintenance.
(4)
Stabilization of drainage systems. The developer shall stabilize and protect all drainageways. Ditches and open channels shall be seeded, sodded or paved depending upon grades and soil types. The conveyance system shall be stable during routine and storm flow conditions. Generally ditches or channels with grades:
(5)
Classifications.
(a)
Minor. The developer shall construct all minor drainage system components necessary to reduce inconvenience and damages from frequent storms. Minor drainage components shall include all inlets, piping, gutters, channels, ditching, pumping and other facilities designed to accommodate the post-development runoff resulting from a ten-year, twenty-four-hour rainfall. Temporary accumulations of storm runoff from ponding or flowing water, in or near minor system components, shall be permitted, provided such accumulations do not encroach on any traffic lane of any collector or arterial street, nor on the center 24 feet of any local street, except on cul-de-sac or permanently dead-end streets serving fewer than 10 dwelling units, where such accumulations may not overtop the curb. In drainageways and drainage easements, runoff shall be contained within the drainageway or drainage easement. Cross-street drainage channels (valley gutters) shall not be permitted except on cul-de-sac or permanent dead-end streets serving fewer than 10 dwelling units and where the minimum grade in the valley gutter and street gutter between the valley gutter and the next downstream drainage inlet is not less than 1%.
(b)
Major. The developer shall pay for all major drainage system components necessary to reduce inconvenience and damages from infrequent storms. Major system components shall include large channels and drainageways, streets, easements and other paths and shall be capable of accommodating post-development runoff in excess of that accommodated by minor system components resulting from twenty-four-hour rainfall events for storms with return frequencies greater than five years up to and including the one-hundred-year return event. On local and collector streets, drainageways, and drainage easements, accumulations of water shall not inundate any buildings at the ground line, unless such buildings are floodproofed. On arterial streets and in nonresidential zoning districts, accumulations of water shall not inundate any buildings at the ground line, unless such buildings are floodproofed and the depth of water at the street crown shall not exceed six inches to permit operation of emergency vehicles.
(6)
Open channels. For publicly owned or maintained open channel conveyance systems, the peak flow rate from the twenty-five-year rainfall event shall be completely contained in the channel banks.
(a)
For storm events between the ten-year and one-hundred-year, twenty-four-hour event, ponding may be contained within existing or proposed street right-of-way as approved by the Director. In no case shall the depth of water exceed 12 inches at the outer edge of pavement or six inches at the road crown, whichever is less.
(b)
The one-hundred-year storm runoff flow path outside of the normal conveyance system must not impact structural improvements on property.
(c)
Where open channels are improved in either the minor or major drainage system, they shall be designed to minimize and accommodate routine maintenance requirements and maximize safety. Drainage easements (in lieu of dedications) shall encompass both the open channels and accommodate routine maintenance and access. Side slopes shall not exceed a four-to-one slope. Drainageways with grades of 0.8% or less (or where subject to high groundwater, continuous flows, or other conditions as determined by the Director or Village Engineer that would hamper maintenance operations due to consistently wet conditions) shall have a paved concrete invert of not less than eight feet wide and side slopes to a point one foot above the channel invert.
(d)
Where invert paving is not required, the drainageway bottom shall be grass. If the drainageway has a bare soil bottom or the natural grasses in the drainageway are disturbed the drainageway bottom shall be sodded and securely staked to one foot above the elevation of inundation resulting from a predevelopment five-year, twenty-four-hour storm event. Other disturbed areas shall be seeded and stabilized to accommodate routine flows and velocities. Grass-lined channels shall be designed and constructed to be stable during routine and high flow conditions.
(e)
Stabilization fabric. Either temporary (biodegradable) or permanent stabilization fabrics may be used to provide stable channels that do not erode.
(7)
Emergency overland flow routes for all stormwater facilities shall be provided so that discharged flows do not exceed the safe capacity of downstream drainage facilities and endanger downstream property or public safety.
(8)
Sewer pipes.
(a)
Unless otherwise approved by the Village Engineer, all drainage piping in street rights-of-way shall be a minimum of 15 inches in diameter and be constructed of materials identified in the construction standards.
(b)
Piping materials outside of rights-of-way shall be a minimum of 15 inches in diameter, be constructed of materials identified in the construction standards and otherwise subject to approval by the Director and/or Village Engineer.
(c)
Open drainage inlet pipes or culverts with any opening dimension in excess of 18 inches shall be equipped with debris grates having an exposed area at least seven times the pipe opening area to avoid backwater accumulations from trash buildup and unsafe stream velocities and a maximum opening size of six inches.
(d)
Drainage outfalls with any opening dimension in excess of 36 inches shall be protected from unauthorized entry by fencing, partial or total submergence of the outlet, debris grates or other methods approved by the Director and/or Village Engineer unless in such a location as to render routine maintenance operations impractical. Outfalls and their channels shall be stable and protected from damages due to scour and erosion.
(e)
Storm sewer laterals are required except as provided in Subsection D(8)(e)[2][a] below.
[2]
Existing development.
[a]
An existing property owner shall be exempt from the storm lateral requirements set forth in Subsection D(8)(e)[1] for a lot when the Village determines that all of the following conditions are met:
[i]
The lot is a riparian lot, abuts a designated floodplain, or is a currently undeveloped lot with the ability to access the storm sewer system in the future that would not require damage or change to existing infrastructure or roadway pavement;
[ii]
The proposed or existing use of the property does not unreasonably alter the natural course or amount of stormwater draining onto adjacent properties as required by state law; and
[iii]
Stormwater draining from the lot is not directed so as to enter the Village's municipal separate storm sewer system or other stormwater conveyance system, except stormwater draining by natural overland flow.
[b]
Duplex/two family/condominium properties shall have a minimum of one storm lateral.
[3]
Storm laterals shall comply with the Village construction standards.
(f)
Agricultural/other drain tiles which are encountered during construction shall be restored, reconnected or connected to public storm drainage facilities.
(g)
For publicly owned or maintained storm sewer conveyance systems, the peak flow rate from the ten-year rainfall event shall be completely contained within the pipes with no "surcharging" or pressurized flow. The system performance shall be evaluated for the twenty-five-year rainfall event. The Director shall have the authority to require sewer pipes convey greater than the ten-year event without "surcharge" conditions.
(h)
For privately owned or maintained storm sewer conveyance systems, the peak flow rate from the ten-year rainfall event shall be completely contained within the pipes with no "surcharging" or pressurized flow. The system performance shall be evaluated for the twenty-five-year rainfall event.
(9)
Drainage from off-site tributary areas shall be conveyed in the improvements. The site improvements shall not block or impede drainage from off-site areas.
(10)
Upstream drainage. Stormwater runoff from upstream of the development shall be conveyed through or diverted around the subject property to limit erosion and flooding.
(11)
Discharges.
(a)
All discharges will be restricted to public drainage systems (including storm sewers and open channels) or to waters of the state.
(b)
Redirecting drainage from original location.
[1]
The applicant is responsible for obtaining all necessary easements, agreements, property interests and approvals from adjacent property owners regarding discharging either drainage improvements or "redirected" drainage discharges onto private lands (when predevelopment drainage had previously not flowed onto the subject property).
[2]
Where site development or redevelopment involves changes in direction, increases in peak rate and/or total volume of runoff from a site (exceeding existing/predevelopment two-year event peak discharges), the Director may require the responsible party to make appropriate legal arrangements with affected property owners concerning the prevention of endangerment to property or public safety, which shall include to indemnify and hold harmless the Village.
E.
Basins.
(1)
General standards for detention/retention storage. The developer may employ on-site detention to control erosion and sedimentation, reduce the post-development peak runoff rate or temporarily store stormwater runoff due to limited capacity of downstream drainage facilities and to improve water quality. The facilities shall be subject to the following general standards:
(a)
Where on-site basins are temporarily employed for erosion and sedimentation control, the facilities shall contain the predevelopment runoff from a twenty-five-year storm event of twenty-four-hour duration within the limits of the facility.
(b)
Where on-site basins are permanently employed to reduce the post-development peak runoff, the detention facility shall safely contain the post-development runoff from a twenty-five-year storm event within the facility limits.
(c)
Detention facility peak discharge rates for the maximum storm required to be contained shall not exceed the predevelopment peak discharge rate from a five-year storm event or the capacity of the downstream drainage facilities, whichever is less.
(d)
All temporary basins shall contain or pass the runoff from any storm of any duration which exceeds the maximum storm required to be contained up to the one-hundred-year storm event.
(e)
All permanent basins shall contain the runoff from the one-hundred-year storm event on both public and, if necessary, private properties without inundating any building at the ground elevation, the travel lanes of any arterial street, the center 10 feet of any collector street or the top of the curb on any local street.
(f)
The storage of stormwater runoff shall not encroach on any public park (except parks designed with detention facilities) or any private lands outside the development unless an easement providing for such storage has been approved and recorded for said lands.
(g)
All basins shall be designed with the safety of the general public and any considerations for ease of maintenance as top priorities.
(h)
Any wet detention facilities shall include riprap to not less than two feet above the normal pool elevation for protection from wave action.
(i)
The sides of all detention facilities shall have a maximum slope ratio of four to one (horizontal to vertical), with flatter slopes being required where determined practical by the Village.
(j)
The Board, upon recommendation by the Director and/or Village Engineer, may require the installation of fencing or other such security measures in basins that are frequently flooded, have long down times or permanent water features, or other features requiring additional security for safety reasons.
(2)
Detention (dry). Detention basins shall be employed to reduce peak flows and prevent downstream flooding. They may be designed and constructed to improve water quality. They shall be designed and constructed to accommodate routine entry and maintenance. Bottom floors shall be sloped to provide positive drainage (one-percent minimum slope).
(3)
Retention (wet). Retention basins shall be employed to reduce peak flows, prevent downstream flooding and improve water quality. They shall be designed and constructed to accommodate routine entry and maintenance. Bottom floors and/or accessways shall be sloped to provide positive drainage (one-percent minimum slope).
F.
Infiltration. Best management practices shall be designed, installed, and maintained to infiltrate runoff to the maximum extent practicable in accordance with the following, except as provided in Subsection F(6) through (9):
(1)
For residential developments, one of the following shall be met:
(a)
Infiltrate sufficient runoff volume so that the post-development infiltration volume shall be at least 90% of the predevelopment infiltration volume, based on an average annual rainfall. However, when designing appropriate infiltration systems to meet this requirement, no more than 1% of the project site is required as an effective infiltration area.
(b)
Infiltrate 25% of the post-development runoff from the two-year twenty-four-hour design storm with a Type II distribution. Separate curve numbers for pervious and impervious surfaces shall be used to calculate runoff volumes and not composite curve numbers as defined in TR-55. However, when designing appropriate infiltration systems to meet this requirement, no more than 1% of the project site is required as an effective infiltration area.
(2)
For nonresidential development, including but not limited to business park, commercial, industrial and institutional development, one of the following shall be met:
(a)
Infiltrate sufficient runoff volume so that the post-development infiltration volume shall be at least 60% of the predevelopment infiltration volume, based on an average annual rainfall. However, when designing appropriate infiltration systems to meet this requirement, no more than 2% of the project site is required as an effective infiltration area.
(b)
Infiltrate 10% of the runoff from the two year, twenty-four-hour design storm with a Type II distribution. Separate curve numbers for pervious and impervious surfaces shall be used to calculate runoff volumes and not composite curve numbers as defined in TR-55. However, when designing appropriate infiltration systems to meet this requirement, no more than 2% of the project site is required as an effective infiltration area.
(3)
Method. A model that calculates runoff volume (such as SLAMM, P8 or other equivalent method as approved by the Director) shall be used.
(5)
Before infiltrating runoff, pretreatment shall be required for parking lot runoff and for runoff from new road construction in areas including but not limited to business parks, commercial, industrial and institutional areas that will enter an infiltration system. The pretreatment shall be designed to protect the infiltration system from clogging prior to scheduled maintenance and to protect groundwater quality in accordance with Subsection D(8). Pretreatment options may include, but are not limited to, oil/grease separation, sedimentation, biofiltration, filtration, swales or filter strips.
(6)
Exclusions. The following areas are not required to meet the requirements of Subsection D et seq.:
(a)
Areas associated with tier one industrial facilities identified in § NR 216.21(2)(a), Wis. Adm. Code, including storage, loading, rooftop and parking.
(b)
Storage and loading areas of Tier 2 industrial facilities identified in § NR 216.21(2)(b), Wis. Adm. Code.
(c)
Fueling and vehicle maintenance areas.
(d)
Areas within 1,000 feet upgradient or within 100 feet downgradient of karst features.
(e)
Areas with less than three feet separation distance from the bottom of the infiltration system to the elevation of seasonal high groundwater or the top of bedrock, except this subsection does not prohibit infiltration of roof runoff.
(f)
Areas with runoff from industrial, commercial and institutional parking lots and roads and residential arterial roads with less than five feet separation distance from the bottom of the infiltration system to the elevation of seasonal high groundwater or the top of bedrock.
(g)
Areas within 400 feet of a community water system well as specified in § NR 811.16(4), Wis. Adm. Code, or within 100 feet of a private well as specified in § NR 812.08(4), Wis. Adm. Code, for runoff infiltrated from commercial, industrial and institutional land uses or regional devices for residential development.
(h)
Areas where contaminants of concern, as defined in § NR 720.03(2), Wis. Adm. Code, are present in the soil through which infiltration will occur.
(i)
Any area where the soil does not exhibit one of the following soil characteristics between the bottom of the infiltration system and the seasonal high groundwater and top of bedrock: at least a three-foot soil layer with 20% fines or greater or at least a five-foot soil layer with 10% fines or greater. This does not apply where the soil medium within the infiltration system provides an equivalent level of protection. This subsection does not prohibit infiltration of roof runoff.
(7)
Exemptions. The following areas are not required to meet the requirements of Subsection D et seq.:
(a)
Areas where the infiltration rate of the soil is less than 0.6 inch/hour measured at the site.
(b)
Parking areas and access roads less than 5,000 square feet for areas including but not limited to business park, commercial and industrial development.
(c)
Redevelopment post-construction sites.
(d)
Infill development areas less than five acres.
(e)
Infiltration areas during periods when the soil on the site is frozen.
(f)
Roads in areas including but not limited to business park, commercial, industrial and institutional land uses and arterial residential roads.
(8)
Where alternate uses of runoff are employed, such as for toilet flushing, laundry or irrigation, such alternate use shall be given equal credit toward the infiltration volume required by this subsection.
(9)
Groundwater protection.
(a)
Infiltration systems designed in accordance with this subsection shall, to the extent technically and economically feasible, minimize the level of pollutants infiltrating to groundwater and shall maintain compliance with the preventive action limit at a point of standards application in accordance with Ch. NR 140, Wis. Adm. Code. However, if site-specific information indicates that compliance with a preventive action limit is not achievable, the infiltration BMP may not be installed or shall be modified to prevent infiltration to the maximum extent practicable.
G.
Protective areas.
(1)
"Protective area" means an area of land that commences at the top of the channel of lakes, streams and rivers, or at the delineated boundary of wetlands, and that is the greatest of the following widths, as measured horizontally from the top of the channel or delineated wetland boundary to the closest impervious surface. However, in this subsection, "protective area" does not include any area of land adjacent to any stream enclosed within a pipe or culvert, such that runoff cannot enter the enclosure at this location.
(a)
For outstanding resource waters and exceptional resource waters and for wetlands in areas of special natural resource interest as specified in § NR 103.04, Wis. Adm. Code.: 75 feet.
(b)
For perennial and intermittent streams identified on a United States Geological Survey 7.5-minute series topographic map, or a county soil survey map, whichever is more current: 50 feet.
(c)
For lakes: 50 feet.
(d)
For highly susceptible wetlands: 50 feet. "Highly susceptible wetlands" include the following types: fens, sedge meadows, bogs, low prairies, conifer swamps, shrub swamps, other forested wetlands, fresh wet meadows, shallow marshes, deep marshes and seasonally flooded basins. Wetland boundary delineations shall be made in accordance with § NR 103.08(1m), Wis. Adm. Code. This subsection does not apply to wetlands that have been completely filled in accordance with all applicable state and federal regulations. The protective area for wetlands that have been partially filled in accordance with all applicable state and federal regulations shall be measured from the wetland boundary delineation after fill has been placed.
(e)
For less susceptible wetlands: 10% of the average wetland width, but no less than 10 feet nor more than 30 feet. "Less susceptible wetlands" include degraded wetlands dominated by invasive species such as reed canary grass.
(g)
For concentrated flow channels with drainage areas greater than 130 acres: 10 feet.
(2)
This subsection applies to post-construction sites located within a protective area, except those areas exempted pursuant to Subsection G(4).
(3)
The following requirements shall be met:
(a)
Impervious surfaces shall be kept out of the protective area to the maximum extent practicable. The stormwater management plan shall contain a written site-specific explanation for any parts of the protective area that are disturbed during construction.
(b)
Where land disturbing construction activity occurs within a protective area, and where no impervious surface is present, adequate sod or self-sustaining vegetative cover of 70% or greater shall be established and maintained. The adequate sod or self-sustaining vegetative cover shall be sufficient to provide for bank stability, maintenance of fish habitat and filtering of pollutants from upslope overland flow areas under sheet flow conditions. Nonvegetative materials, such as rock riprap, may be employed on the bank as necessary to prevent erosion, such as on steep slopes or where high-velocity flows occur.
(c)
Best management practices such as filter strips, swales, or wet detention basins that are designed to control pollutants from nonpoint sources may be located in the protective area.
(4)
Exemptions. This Subsection G relating to protective areas does not apply to:
(a)
Redevelopment post-construction sites less than five acres.
(b)
Infill development areas less than five acres.
(c)
Structures that cross or access surface waters such as boat landings, bridges and culverts.
(d)
Structures constructed in accordance with § 59.692(1v), Wis. Stats.
(e)
Post-construction sites from which runoff does not enter the surface water, except to the extent that vegetative ground cover is necessary to maintain bank stability.
H.
Fueling and maintenance areas. Fueling and vehicle maintenance areas shall, to the maximum extent practicable, have BMPs designed, installed and maintained to reduce petroleum within runoff, such that the runoff that enters waters of the state contains no visible petroleum sheen.
I.
Swale treatment for transportation facilities.
(1)
Applicability. Except as provided in Subsection I(2), transportation facilities that use swales for runoff conveyance and pollutant removal meet all of the requirements of this section, if the swales are designed to the maximum extent practicable to do all of the following:
(a)
Where appropriate and approved, nonvegetative measures may be employed to prevent erosion or provide for runoff treatment, such as rock riprap stabilization or check dams.
(b)
Carry runoff through a swale for 200 feet or more in length that is designed with a flow velocity no greater than 1.5 feet per second for the peak flow generated using either a two-year, twenty-four-hour design storm or a two-year storm with duration equal to the time of concentration as appropriate. If a swale of 200 feet in length cannot be designed with a flow velocity of 1.5 feet per second or less, then the flow velocity shall be reduced to the maximum extent practicable.
(2)
Exemptions. The Director may, consistent with water quality standards, require other provisions of this section to be met on a transportation facility with an annual average daily travel (AADT) of vehicles greater than 2,500 and where the initial surface water of the state that the runoff directly enters is any of the following:
(a)
An outstanding resource water.
(b)
An exceptional resource water.
(c)
Waters listed in Federal Clean Water Act § 303(d) that are identified as impaired, in whole or in part, due to nonpoint source impacts.
(d)
Waters where targeted performance standards are developed under § NR 151.004, Wis. Adm. Code, to meet water quality standards.
The following considerations shall be observed in managing runoff:
B.
Emergency overland flow routes for all stormwater facilities shall be provided so that discharge flow rates do not exceed the safe capacity of downstream drainage facilities or endanger downstream property or public safety.
C.
Unique site conditions. The management plan shall consider and accommodate conditions unique to the site that are not otherwise addressed in this chapter. Unique conditions may including but are not limited to: steep slopes, active and apparent karst features, elevated groundwater, limited downstream drainage capacity, previously altered conditions, shallow soils, and small sites with limited space. Unique conditions and resulting approaches shall be reviewed and approved by the Director.
A.
The BMPs may be located on site or off site as part of a regional stormwater device, practice or system.
B.
Post-construction runoff within nonnavigable surface water that flows into a BMP, such as a wet detention pond, is not required to meet the performance standards of this chapter. Post-construction BMPs may be located in nonnavigable surface waters.
C.
Except as allowed under this section, post-construction runoff from new development shall meet the post-construction performance standards prior to entering navigable surface water.
D.
Post-construction runoff from any development within a navigable surface water that flows into a BMP is not required to meet the performance standards of this chapter if:
E.
Runoff from existing development, redevelopment and infill areas shall meet the post-construction performance standards in accordance with this subsection.
(1)
To the maximum extent practicable, BMPs shall be located to treat runoff prior to discharge to navigable surface waters.
(2)
Post-construction BMPs for such runoff may be located in navigable surface water if allowable under all other applicable federal, state and local regulations such as Ch. NR 103, Wis. Adm. Code, and Ch. 30, Wis. Stats.
F.
The discharge of runoff from a BMP, such as a wet detention pond, or after a series of such BMPs is subject to this chapter.
G.
The Director may approve off-site management improvements, provided that all of the following conditions are met:
(1)
The Director determines that the post-construction runoff is covered by a stormwater management system plan that is approved by the Village and that contains management requirements consistent with the purpose and intent of this chapter.
(2)
The off-site facility meets all of the following conditions:
(a)
The facility is in place.
(b)
The facility is designed and adequately sized to provide a level of stormwater control equal to or greater than that which would be afforded by on-site practices meeting the performance standards of this chapter.
(c)
The facility has a legally obligated entity responsible for its long-term operation and maintenance.
H.
Where an area-wide or regional treatment alternative exists such that the Director exempts the applicant from all or part of the minimum on-site stormwater management requirements, the applicant shall be required to pay a fee (fee in lieu) in an amount determined in negotiation with the Committee. The value of the contributing fee shall be based on prorated benefit. In determining the fee for post-construction runoff, the Committee shall consider an equitable distribution of the cost for land, engineering design, construction, and maintenance of the regional treatment option.
No responsible party may undertake a land disturbing construction activity which is not otherwise exempted or excluded from the provisions of this chapter without receiving a post-construction runoff permit from the Director prior to commencing the proposed activity.
A.
Permit application and fees. Unless specifically excluded by this chapter, any responsible party desiring a permit shall submit to the Director a permit application made on a form provided by the Director for that purpose.
(1)
Unless otherwise excepted by this chapter, a permit application must be accompanied by a stormwater management plan, a maintenance agreement and a nonrefundable permit administration fee.
(2)
The stormwater management plan shall be prepared to meet the requirements of §§ 330-21, 330-23 to 330-26 and 330-28. The maintenance agreement shall be prepared to meet the requirements of § 330-29. The financial security shall meet the requirements of § 330-10, and fees shall be those established by the Board as set forth in § 330-9.
B.
Review and approval of permit application. The Director shall review any permit application that is submitted with a stormwater management plan, maintenance agreement, and the required fee. The following approval procedure shall be used:
(1)
Within 20 business days of the receipt of a complete permit application, including all items as required by Subsection A, the Director shall inform the applicant whether the application, plan and maintenance agreement are approved or disapproved based on the requirements of this chapter.
(2)
If the stormwater permit application, plan and maintenance agreement are approved, or if an agreed upon payment of fees in lieu of stormwater management practices is made, the Director shall issue the permit.
(3)
If the stormwater permit application, plan or maintenance agreement is disapproved, the Director shall detail in writing the reasons for disapproval.
(4)
The Director may request additional information from the applicant. If additional information is submitted, the Director shall have 20 business days from the date the additional information is received to inform the applicant that the plan and maintenance agreement are either approved or disapproved.
(5)
Failure by the Director to inform the permit applicant of a decision within 20 business days of a required submittal shall be deemed to mean approval of the submittal and the applicant may proceed as if a permit had been issued.
D.
Permit requirements. All permits issued under this chapter shall be subject to the following conditions, and holders of permits issued under this chapter shall be deemed to have accepted these conditions. The Director may suspend or revoke a permit for violation of a permit condition, following written notification of the responsible party. An action by the Director to suspend or revoke this permit may be appealed in accordance with § 330-12.
(1)
Other jurisdictions. Compliance with this permit does not relieve the responsible party of the responsibility to comply with other applicable federal, state, and local laws and regulations.
(2)
The responsible party shall design and install all structural and nonstructural stormwater management measures in accordance with the approved stormwater management plan and this permit.
(3)
Notification. The responsible party shall notify the Director at least 10 business days before commencing any work in conjunction with the stormwater management plan, and within five business days upon completion of the stormwater management practices. If required as a special condition under Subsection E, the responsible party shall make additional notification according to a schedule set forth by the Director so that BMP installations can be inspected during construction.
(4)
Observation and documentation.
(a)
Construction improvements required as part of this chapter shall be documented through record drawings (certified "as built" by a licensed professional engineer). The developer shall provide the record drawings in an electronic and permanent hard copy format as approved by the Director and identified in Chapter 415, Zoning.
(b)
Completed stormwater management practices must pass a final observation by the Director or his designee to determine if they are in accordance with the approved stormwater management plan and this chapter. The Director or his designee shall notify the responsible party in writing of any changes required in such practices to bring them into compliance with the conditions of this permit.
(5)
The responsible party shall notify the Director of any significant modifications it intends to make to an approved stormwater management plan. The Director shall review and approve the proposed modifications prior to incorporation into the stormwater management plan, construction and execution by the responsible party.
(6)
Maintenance. The responsible party shall maintain all stormwater management practices in accordance with the stormwater management plan until the practices either become the responsibility of the Village or are transferred to subsequent private owners as specified in the approved maintenance agreement.
(7)
Corrective actions. The responsible party authorizes the Director to perform any work or operations necessary to bring stormwater management measures into conformance with the approved stormwater management plan and consents to a special assessment or charge against the property as authorized under Ch. 66, Subch. VII, Wis. Stats., or to charging such costs against the financial security posted under § 330-10.
(8)
If so directed by the Director, the responsible party shall repair at the responsible party's own expense all damage to adjoining municipal facilities and drainageways caused by runoff, where such damage is caused by activities that are not in compliance with the approved stormwater management plan.
(9)
Building permit. Issuance of a building permit shall be contingent upon the applicant providing documents that identify structures that shall be constructed to comply with this chapter.
(10)
Access permitted. The responsible party shall permit property access to the Director or his designee for the purpose of inspecting the property for compliance with the approved stormwater management plan and this permit.
(11)
The responsible party is subject to the enforcement actions and penalties detailed in § 330-11, if the responsible party fails to comply with the terms of this permit.
(12)
Occupancy permitted. The Village reserves the right not to grant an occupancy permit until stormwater management and site stabilization efforts are completed.
A.
General. The developer shall submit to the Village at the time of filing either a preliminary plat (or development plan), a preliminary drainage plan and/or engineering report on the ability of existing watercourse channels, storm sewers, culverts and other improvements pertaining to drainage or flood control within the development to accommodate the additional runoff which would be generated by the development of the land. Additional information shall be submitted to confirm that drainage discharges do not damage the improved or unimproved land up or downstream from the proposed development.
B.
Plan requirements. The stormwater management plan required under Subsection A shall contain a minimum of the following information:
(1)
Contact persons. Name, address, and telephone number for the following or their designees: landowner; developer; project engineer for practice design and certification; person(s) responsible for installation of stormwater management practices; and person(s) responsible for maintenance of stormwater management practices prior to the transfer, if any, of maintenance responsibility to another party.
(2)
A land survey document (legal description and map) of the property proposed to be developed, referenced to the United States Public Land Survey system or to block and lot numbers within a recorded land subdivision plat. The documents shall be prepared by a Wisconsin professional land surveyor.[1]
(3)
Drainage easements.
(a)
Public (reference Chapter 408, Subdivision of Land). Public drainage easements shall be dedicated when drainage from two or more properties is conveyed across an adjoining downstream property.
(b)
Private. The developer/property owner may identify private drainage easements on survey documents that are recorded with the County Register of Deeds. The Village has the authority to require proposed private drainage easements to be improved and dedicated as public.
(4)
Predevelopment site conditions, including:
(a)
One or more site maps at a scale of not less than one inch equals 40 feet. The site maps shall show the following: site location and legal property description; predominant soil types and hydrologic soil groups; existing cover type and condition; topographic contours of the site at an interval not to exceed two feet; topography and drainage network including enough of the contiguous properties to show runoff patterns onto, through, and from the site; watercourses that may affect or be affected by runoff from the site; flow path and direction for all stormwater conveyance sections; watershed boundaries used in hydrology determinations to show compliance with performance standards; lakes, streams, wetlands, channels, ditches, and other watercourses on and immediately adjacent to the site; limits of the one-hundred-year floodplain; location of wells and wellhead protection areas covering the project area and delineated pursuant to § NR 811.16, Wis. Adm. Code.
(b)
Hydrology and pollutant loading computations as needed to show compliance with performance standards. All major assumptions used in developing input parameters shall be clearly stated. The geographic areas used in making the calculations shall be clearly cross-referenced to the required map(s).
(5)
Post-development site conditions, including:
(a)
Explanation of the provisions to preserve and use natural topography and land cover features to minimize changes in peak flow runoff rates and volumes to surface waters and wetlands.
(b)
Explanation of any restrictions on stormwater management measures in the development area imposed by wellhead protection plans and ordinances.
(c)
One or more site maps at a scale of not less than one inch equals 40 feet showing the following:
[1]
Post-construction pervious areas including vegetative cover type and condition.
[2]
Impervious surfaces including all buildings, structures, and pavement.
[3]
Post-construction topographic contours of the site at an interval not to exceed two feet.
[4]
A master site grading and drainage plan for the development (including but not limited to streets, blocks and lots) that identifies existing and proposed grades, contours and drainage patterns. The plan shall identify that the proposed development shall accommodate both existing and future off-site drainage.
[5]
Post-construction drainage network including enough of the contiguous properties to show runoff patterns onto, through, and from the site; locations and dimensions of drainage easements.
[6]
Locations of maintenance easements specified in the maintenance agreement.
[7]
Flow path and direction for all stormwater conveyance sections.
[8]
Location and type of all stormwater management conveyance and treatment practices, including the on-site and off-site tributary drainage area.
[9]
Location and type of conveyance system that will carry runoff from the drainage and treatment practices to the nearest adequate outlet such as a curbed street, storm drain, or natural drainageway.
[10]
Watershed boundaries used in hydrology and pollutant loading calculations and any changes to lakes, streams, wetlands, channels, ditches, and other watercourses on and immediately adjacent to the site.
[11]
Estimates of the quantity of drainage entering the development from adjoining upstream lands (post-construction condition).
[12]
Quantities of flow at each inlet or culvert.
[13]
Location, sizes and grades of required culverts, storm drainage sewers and other required appurtenances.
(d)
Construction documents (plan drawings and specifications) for all site improvements. Material and construction specifications for all drainage improvements (e.g., pipe, culverts, seed, sod, etc.) shall comply with the Village construction standards and this chapter.
(e)
Hydrology and pollutant loading computations as needed to show compliance with performance standards. The computations shall be made for each discharge point in the development, and the geographic areas used in making the calculations shall be clearly cross-referenced to the required map(s). The plan shall address drainage that enters the development from adjoining areas outside the development.
(f)
Subsurface conditions. Results of investigations of soils and groundwater required for the placement and design of stormwater management measures. Detailed drawings including cross sections and profiles of all permanent stormwater conveyance and treatment practices.
(7)
An operation and maintenance plan developed for the life of each stormwater management practice, including the required maintenance activities and maintenance activity schedule.
(8)
Opinions of probable construction cost (i.e., estimates) for the construction, operation, and maintenance of each stormwater management practice.
(9)
Other information requested in writing by the Director to determine compliance of the proposed stormwater management measures with the provisions of this chapter.
(10)
All site investigations, plans, designs, computations, and drawings shall be certified by a Wisconsin licensed professional engineer to be prepared in accordance with accepted engineering practice and requirements of this chapter.
A.
Maintenance agreement required. The maintenance agreement required under § 330-27A for stormwater management practices shall be an agreement between the Village and the responsible party to provide for maintenance of stormwater practices beyond the duration period of this permit. The maintenance agreement shall be filed with the County Register of Deeds as a property deed restriction so that it is binding upon all subsequent owners of the land served by the stormwater management practices.
B.
Agreement provisions. The maintenance agreement shall contain the following information and provisions and be consistent with the operation and maintenance plan required by § 330-28B(7):
(1)
Identify drainage improvements. Identify the stormwater facilities and designation of the drainage area served by the facilities.
(2)
Maintenance schedule. A schedule for regular maintenance of each aspect of the stormwater management system consistent with the stormwater management plan required under § 330-27A. Requirement that the responsible party(s) or organization shall maintain stormwater management practices in accordance with the schedule included in § 330-28B(7) and this subsection.
(3)
Parties responsible for maintenance. Identify the responsible party(s) or organization responsible for long-term maintenance of the stormwater management practices identified in the stormwater management plan required under § 330-27A.
(4)
Access authorization. Authorization for the Director to access the property to conduct inspections of stormwater management practices as necessary to ascertain that the practices are being maintained and operated in accordance with the agreement.
(5)
Document site observations. A requirement for the Director to maintain public records of the results of the site inspections, to inform the responsible party responsible for maintenance of the inspection results, and to specifically indicate any corrective actions required to bring the stormwater management practice into proper working condition.
(6)
Corrective actions. Agreement that the party designated under Subsection B(3) as responsible for long-term maintenance of the stormwater management practices shall be notified by the Director and/or Public Works Committee of maintenance problems which require correction. The specified corrective actions shall be undertaken within a reasonable time frame as set by the Director.
(7)
Authorization to correct. Authorization of the Director to perform the corrective actions identified in the inspection report if the responsible party designated under Subsection B(3) does not make the required corrections in the specified time period. The Director shall enter the amount due on the tax rolls and collect the money as a special charge against the property pursuant to Ch. 66, Subch. VII, Wis. Stats.
C.
Termination of agreement. The agreement shall terminate after the subject improvements are constructed, improvements and lands/easements are dedicated to the Village, all administrative and code requirements are completed, and the Village has observed the work and identified the project is complete.