§ 34-110. Stormwater management plan requirements.

(a)

General stormwater management plan requirements. A storm water management plan shall describe how the permit holder and other responsible parties will meet the storm water management requirements of this section and other related requirements in this division. All storm water management plans and associated BMPs shall comply with the planning, design, implementation and maintenance requirements described in this division and the technical standards prepared by the Wisconsin Department of Natural Resources.

(b)

Guiding principles for stormwater management. To satisfy the requirements of this section, a storm water management plan shall, to the maximum extent practicable, adhere to the following guiding principles:

(1)

Preserve natural watershed boundaries and drainage patterns;

(2)

Reserve adequately sized areas for storm water infiltration, detention and treatment early in the site planning process;

(3)

Locate storm water BMPs prior to runoff leaving the site or entering waters of the state, and outside of wetlands, floodplains, primary or secondary environmental corridors or isolated natural areas;

(4)

Minimize soil compaction and maintain pre-development groundwater recharge areas;

(5)

Minimize impervious surfaces and have them drain to vegetated areas for pollutant filtering and infiltration;

(6)

Emphasize vegetated swales, warm season and wetland plantings, and low flow velocities for storm water conveyance, treatment and infiltration, especially for transportation related projects;

(7)

Allow for different storm water management strategies for cleaner runoff (i.e. roofs) versus more polluted runoff (i.e. heavily used streets and parking lots);

(8)

Provide for emergency overflow in all storm water BMP designs;

(9)

Distribute storm water bioretention and infiltration BMPs throughout the site plan for large land developments;

(c)

Site plan map requirements. A site plan map and supporting data of site conditions at a scale of one inch equals no more than 100 feet (unless otherwise noted) shall delineate or display all the following applicable items:

(1)

Development title, graphic scale and north arrow;

(2)

Property location description by public land survey system (1/4 section, section, township, range, village);

(3)

Location map (smaller scale) showing the site location within a public land survey section or subdivision, oriented the same as subsection (4) below;

(4)

Ownership boundaries, bearings, lengths and other survey references that will accurately identify the sites location, in accordance with W.S.A., ch. 236, and village mapping standards for all land divisions;

(5)

Lot numbers and dimensions, including outlots for all land divisions;

(6)

Name and complete contact information for the applicant, landowner, developer and project engineer;

(7)

Surveyor's certificate, signed, dated and sealed for all land divisions;

(8)

Sheet numbers and revision dates on every page;

(9)

Existing site topography at a contour interval not to exceed two feet, including spot elevations for physical features such as storm sewers and culverts (invert elevations), retaining walls, road and ditch centerlines and topographic high and low points;

(10)

Location and name, if applicable, of all lakes, streams, channels, ditches, and other water bodies or areas of channelized flow on or adjacent to the site;

(11)

Location and name, if applicable, of all wetlands and identification of source of delineation. These boundaries shall be field verified prior to approval of final land divisions, erosion control plans or storm water management plans;

(12)

Boundaries of shoreland zones and the ordinary high water mark (OHWM) for any navigable water body as defined by the Village of Mukwonago Shoreland and Floodland Protection ordinance. For final land divisions, the OHWM boundaries shall be field verified;

(13)

Boundaries and elevation of the 100-year floodplains, flood fringes and floodways, as defined by the Village of Mukwonago Shoreland and Floodland Protection ordinance. For final land divisions, these boundaries and elevations shall be field verified;

(14)

Boundaries and soil symbol for each soil mapping unit and the identification of all hydric soils as defined by the USDA-Natural Resources Conservation Service;

(15)

Locations of all available soil borings or soil profile evaluations with unique references to supplemental data report forms;

(16)

Location of primary and secondary environmental corridors, as defined by the Southeastern Wisconsin Regional Planning Commission. For final land divisions, these boundaries shall be field verified;

(17)

Location and description of isolated natural area boundaries as defined by the Southeastern Wisconsin Regional Planning Commission, woodland areas and other vegetative cover types;

(18)

Location and descriptive notes for existing and proposed structures within 50 feet of the property boundaries and their proposed use, including, but not limited to buildings and foundations, roads, parking areas, fence lines, access lanes, culverts (include size and type), above ground utilities and retaining walls;

(19)

Location and descriptive notes for other known existing site features including, but not limited to rock outcrops or other karst features, tile drains, buried utilities, dumps, landfills, manure or other waste storage facilities;

(20)

Boundaries and descriptive notes for all applicable setbacks and for "protective areas", as specified in section 34-110(d)(4) of this section;

(21)

Location and descriptive notes for any existing or proposed easements, rights-of-way, vision corners or other known site restrictions. Road right-of ways and building setbacks shall be in compliance with all applicable administrative codes, adopted plans and ordinances;

(22)

Location and descriptive notes for existing and proposed public dedications of parcels or rights-of-way;

(23)

Location and descriptive notes for preplanned building or waste disposal sites, when limited by site features;

(24)

Location and documentation of any existing well and delineation of any applicable regulatory setbacks, in accordance with ch. NR811 and 812 Wis. Admin. Code;

(25)

Notes describing source documents, date and measure of accuracy for all applicable mapping features noted above;

(26)

Other site information that the village determines is necessary to administer this section.

(d)

Specific stormwater management plan requirements and performance standards. All storm water management plans and associated BMPs shall meet the following minimum requirements to the maximum extent practicable. It is highly recommended that the applicant meet with the village engineer prior to preparing a storm water management plan to determine the applicability of these requirements early in the site planning process.

(1)

Peak discharge.

a.

Minimum requirement. To minimize downstream bank erosion and the failure of downstream conveyance systems, the calculated post-development peak storm water discharge rates shall be reduced as depicted in the table below. Modeling requirements for this provision are further described in section 34-111 below.

	Post Development Peak Discharge =	Pre-Development Peak Discharge
Recurrence interval storm	100	10
	10	2
	2	2
	1	1

 

b.

Release rate per acre. The village engineer may establish a maximum allowable release rate on a per acre basis that would supersede the requirements of subsection a. above for certain watersheds after the necessary hydrologic modeling is completed.

c.

Peak discharge exemptions . Certain sites or portions of sites may be exempted from the peak discharge requirements of this subsection in accordance with subsection (e) below.

(2)

Total suspended solids.

a.

By design, each storm water management plan shall meet the following post-development total suspended solids reduction targets, based on average annual rainfalls, as compared to no runoff management controls:

1.

For new land development and in-fill development, 80 percent reduction in total suspended solids load;

2.

For redevelopment, 40 percent reduction of total suspended solids load from parking areas and roads;

(3)

Infiltration.

a.

BMPs shall be designed, installed, and maintained to infiltrate runoff in accordance with the performance standards in Table 1, except as provided in subsection d. through h. below.

TABLE 1

Percent Connected Impervious Surface	Description/Example Land Uses	Post-Development Infiltration Volume a	Maximum Effective Infiltration Area
Up to 40%	Description: Low imperviousness Example land uses: low density residential, parks, cemeteries.	90% of pre-development b	1% of site
>40% up to 80%	Description: Medium imperviousness Example land uses: medium and high density residential, multi-family residential, industrial, institutional, office park	75% of pre-development	2% of site
>80%	Description: High imperviousness Example of land uses: commercial strip malls, shopping centers, commercial downtowns	60% of pre-developments	2% of site

 

^a. All percentages are based on average annual rainfall.

^b. To avoid downstream flooding and chronic wetness issues from storm water discharges, the post-development infiltration volume for low density residential developments shall not be less than 25% of the 2-year, 24-hour storm, in accordance with subsection (7) below.

b.

Modeling. Refer to section 34-111(a) for details on calculating runoff volumes and pre-development conditions.

c.

Pretreatment. Pretreatment shall be required before infiltrating parking lot and road runoff from commercial, industrial and institutional areas. 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 h. below. Pretreatment options may include, but are not limited to, oil/grease separators, sedimentation or bioretention basins, filtration swales or filter strips. All designs shall comply with the technical standards in section 34-111(b).

Note: To achieve the infiltration requirement for the parking lots or roads, "maximum extent practicable" should not be interpreted to require significant topography changes that create an excessive financial burden. To minimize potential groundwater impacts, it is desirable to infiltrate the cleanest runoff. To achieve this, a design may propose greater infiltration of runoff from low pollutant sources such as roofs, and less from higher pollutant source areas such as parking lots.

d.

Infiltration prohibitions. Due to potential for groundwater contamination, runoff shall not be infiltrated and will not be credited toward meeting the requirements of this subsection for the following:

1.

Runoff from outdoor material storage and loading docks for tier 1 and tier 2 industrial facilities, as identified in NR216(2), Wis. Admin. Code. Parking lot runoff from tier 1 industrial facilities is prohibited. Parking lot runoff from tier 2 facilities may be infiltrated but may require pretreatment.

2.

Runoff from fueling and vehicle maintenance areas, not including rooftops and canopies.

3.

Infiltration of runoff within 1,000 feet upgradient or within 100 feet downgradient of karst features.

4.

Areas within 400 feet of a community water system well as specified in NR811.16(4), Wis. Adm. Code, or within 100 feet of a private well as specified in NR812.08(4), Wis. Adm. Code, for runoff infiltrated from commercial, industrial and institutional land uses or regional devices for residential development, not including rooftop runoff.

5.

Areas where contaminants of concern, as defined in NR720.03(2), Wis. Adm. Code are present in the soil through which infiltration will occur.

e.

Separation distances. Infiltration BMPs shall be located so the characteristics of the soil and the separation distance between the bottom of the infiltration BMP and the elevation of the highest groundwater table or the top of bedrock are in accordance with Table 2.

TABLE 2

Source Area	Groundwater or Bedrock Separation Distance	Soil Characteristics
Industrial, commercial and institutional parking lots and roads	5 feet or more	Filtering layer
Residential arterial roads	5 feet or more	Filtering layer
Roofs draining to subsurface infiltration practices	1 foot or more	Native or engineered soil with particles finer than coarse sand.
Roofs draining to surface infiltration practices.	Not applicable	Not applicable
All other impervious source areas	3 feet or more	Filtering layer

 

f.

Infiltration exemptions. The infiltration requirements of this subsection may be exempted by the village where:

1.

The soils at the proposed bottom of an infiltration system have a measured infiltration rate of less than 0.6 inches per hour using a scientifically credible field test method; and

2.

The village determines that it would impracticable to modify existing soil conditions based on soil profile evaluations extending five feet below the proposed bottom of the infiltration system.

Note: USDA soil textures of sandy clay loam, clay loam, silty clay loam, sandy clay, silty clay or clay are generally considerable unsuitable for infiltration and would require replacement or modification.

g.

Alternate runoff uses. Where storage and reuse of runoff are employed, such as, landscape watering, toilet flushing, laundry or irrigation or storage on green roofs where an equivalent portion of the runoff is captured permanently by rooftop vegetation, such alternate uses shall be given equal credit toward the infiltration volume required by this section.

h.

Groundwater protection.

1.

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 Chapter NR109, 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.

2.

Notwithstanding (1) above, the discharge from BMPs shall remain below the enforcement standard at the point of standards application.

3.

All storm water BMPs shall comply with the applicable provisions of Chapter NR815, Wis. Admin. Code relating to injection wells.

4.

All storm water BMPs shall comply with the provisions of any applicable wellhead protection plan for a community water supply under Chapter NR811, Wis. Admin. Code.

(4)

Protective areas.

a.

Definitions. "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 section, "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.

1.

For outstanding resource waters and exceptional resource waters, 75 feet.

2.

For perennial and intermittent streams identified by Waukesha or Walworth County, 50 feet. If there is a discrepancy between the County maps and the applicable United States Geological Survey 7.5-minute series topographic map, the more stringent stream identification shall apply.

3.

For lakes, 50 feet.

4.

For wetlands not subject to 5., 50 feet.

5.

For highly susceptible wetlands, as determined by the village, 75 feet. Highly susceptible wetlands include the following types: calcareous fens, sedge meadows, bogs, low prairies, conifer swamps, lowland hardwood swamps, and ephemeral shrub swamps.

6.

Wetland boundary delineations shall be made in accordance with Chapter NR103, Wis. Admin. Code. This paragraph 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.

7.

For less susceptible wetlands, ten percent of the average wetland width, but no less than ten feet nor more than 30 feet, unless otherwise required by another applicable regulation. Less susceptible wetlands include degraded wetlands dominated by invasive species such as reed canary grass.

8.

In subsection a.1., 4. and 5., determinations of the extent of the protective area adjacent to wetlands shall be made on the basis of the sensitivity and runoff susceptibility of the wetland in accordance with the standards and criteria in Chapter NR103, Wis. Admin. Code.

9.

For concentrated flow channels with drainage areas greater than 130 acres, ten feet.

b.

Requirements. The following requirements shall be met for all land development activity located within a protective area:

1.

Impervious surfaces shall be kept out of the protective area, except for structures as authorized and defined under shoreland and floodland zoning. The erosion control plan shall contain a written site-specific explanation for any parts of the protective area that are disturbed during construction. If there is no practical alternative to locating an impervious surface in the protective area, the storm water management plan shall contain a written site-specific explanation and a technical exemption may be applied for under subsection (e) below.

2.

Where land disturbing activity occurs within a protective area, and where no impervious surface is present, adequate sod or self-sustaining vegetative cover of 70 percent 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. Non-vegetative 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.

3.

Best management practices such as filter strips, swales, or wet detention basins, that are designed to control pollutants from non-point sources may be located in the protective area, but shall not encroach into wetlands, floodplains or primary or secondary environmental corridors.

c.

Protective area exemptions. The protective area requirements of this subsection may be exempted in accordance with subsection (e) below and do not apply to the following:

1.

Structures that cross or access surface waters such as boat landings, bridges and culverts;

2.

Structures constructed in accordance with W.S.A., § 61.351; and

3.

Sites where runoff does not enter the surface water, including wetlands without first being treated by BMP to meet the total suspended solids requirements under subsection 2., above and peak discharge requirements under subsection 1. above, except to the extent that vegetative ground cover is necessary to maintain bank stability.

(5)

Fueling and vehicle maintenance areas. Fueling and vehicle maintenance areas shall 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.

(6)

Site drainage. Measures shall be implemented to ensure proper site drainage, prevent property damage and protect public health and safety, including the following minimum requirements:

a.

Drainage easement. Perpetual drainage easements or other deed restrictions shall be recorded on the property to preserve major storm water flow paths and permanent storm water BMP locations. Covenants in these areas shall not allow buildings or other structures and shall prevent any grading, filling or other activities that interrupt or obstruct flows in any way. Covenants shall also specify maintenance responsibilities and authorities in accordance with section 34-112.

b.

Site grading. Site grading shall ensure positive flows away from all buildings, roads, driveways and septic systems, be coordinated with the general storm water drainage patterns for the area, and minimize adverse impacts on adjacent properties.

c.

Street drainage. All street drainage shall be designed to prevent concentrated flows from crossing the traffic lanes to the maximum extent practicable. Design flow depths at the road centerline for on-street drainage, shall not exceed six inches during the peak flows generated by the 100-year, 24 hour design storm, using planned land use conditions for the entire contributing watershed area.

d.

Bridges and cross-culverts. All new or modified bridges and cross-culverts shall comply with applicable design standards and regulations, facilitate fish passage and prevent increased flooding or channel erosion upstream or downstream from the structure. All bridges and cross culverts on collector and arterial roadways shall be designed to convey the 100-year, 24-hour design storm. All bridges and cross culverts on local roadways shall be designed to convey the ten-year, 24-hour design storm, while providing an overland flow path that does not impact any structures for the 100-year, 24-hour design storm. A floodplain analysis shall be required for all developments impacting a navigable waterway. This analysis must demonstrate no adverse offsite impacts, in accordance with state and federal regulations and may require larger structures than those specified above. Design flow depths at the road centerline for all crossings shall not exceed six inches during the peak flows generated by the 100-year, 24-hour design storm, using planned land use conditions for the entire contributing watershed area. All predevelopment runoff storage areas within the flow path upstream of bridges and cross-culverts shall be preserved and designated as drainage easements, unless compensatory storage is provided and accounted for in modeling. As-built documentation shall be submitted in accordance with section 34-108 for all new or modified structures that are located within a mapped floodplain or that the village engineer determines to be necessary to maintain floodplain modeling for the applicable watershed.

e.

Subsurface drainage. To avoid property and other damage from groundwater, all buildings planned for human occupation on a regular basis shall meet all of the following:

1.

Basement floor surfaces shall be built one foot above the highest groundwater table elevation, as documented in the submitted soil evaluations in accordance with village standards. On sloped sites, basements may be allowed partially below the highest groundwater table only on the upslope side if they meet village drainage system requirements for design discharge and engineering oversight and long term maintenance. For these sites, the one foot groundwater separation will be enforced at the further downslope part of the basement.

2.

Avoid hydric soils as much as possible.

3.

The village engineer shall be notified of any drain tiles that are uncovered during construction, which the village engineer may require to be restored or connected to other drainage systems.

4.

No discharge of groundwater from tile lines, sump pumps or other means shall be allowed onto another person's land or any public space without the written approval of the village and the property owner.

f.

Open channels. All open channel drainage systems shall at a minimum be designed to carry the peak flows from a 100-year, 24-hour design storm using planned land use for the entire contributing watershed area. Side slopes shall be no steeper than 3h:1v unless otherwise approved by the village engineer for unique site conditions. Water surface elevations for the 100-year, 24-hour design storm shall be calculated for all existing and proposed open channels.

g.

Storm sewers. All storm sewers shall be designed to convey the ten-year, 24-hour design storm while providing an overland flow path that does not impact any structures for the 100-year, 24-hour design storm.

h.

Changes to stormwater discharges. The sites where the village determines the post-development stormwater discharge flow paths will be significantly different that pre-development conditions, or where proposed stormwater discharges may otherwise have a significant negative impact on adjacent property owners, the village may require the applicant to obtain written authorization from impacted property owners, record a drainage easement to allow for the flow to cross those impacted properties and/or a hold harmless agreement, holding the village harmless from claims by negatively impacted property owners.

i.

Structure protection and safety. Flows generated by the 100-year, 24-hour design storm under planned land use conditions may exceed the design capacity of conveyance systems, but shall not come in contact with any buildings. For buildings designed for human occupation on a regular basis, the following additional requirements shall apply:

1.

The lowest elevation of the structure that is exposed to the ground surface shall be a minimum of two feet above the maximum water elevation produced by the 100-year, 24 hour design storm, including flows through any storm water BMP that may temporarily or permanently store water at a depth of greater than one foot, and also following the procedures for internally drained areas outlined by Waukesha County; and

2.

The structure shall be setback at least 50 feet from any storm water BMP that may temporarily or permanently store water at a depth of greater than one foot, including any internally drained area with a significant contributing watershed and/or limited runoff storage capacity as determined by the village. Setback distance shall be measured from the closest edge of water at the elevation produced by the 100-year, 24-hour design storm. The village may exempt existing structures and structures with no basement from this requirement if the village determines other site risks are minimal based on soil and site conditions.

(7)

Additional requirements. The village may establish more stringent requirements than the minimums set forth in this section, such as addressing thermal impacts of storm water, downstream flooding, total maximum daily load (TMDL) standard for a watershed, other applicable state or federal laws, an order of any court of competent jurisdiction or chronic wetness conditions, if the village determines that an added level of protection is needed to protect a cold water stream, outstanding water resource or exceptional water resource, environmentally sensitive areas, downstream property or public health or safety.

(e)

Technical exemptions.

(1)

Exemption criteria. Following the provisions of this subsection, the village engineer may recommend to the village board to exempt a site or a portion of a site from meeting certain technical requirements of this section if the village engineer determines that exception criteria under subsection (d) above or one or more of the following applies:

a.

Off-site BMP(s). The requirement has been satisfied through the use of off-site BMP(s). Off-site BMPs could be installed beyond the boundaries of the property covered by the application as part of a regional storm water management plan or through other legal arrangements. However, to be eligible for this exemption, the off-site BMP(s) must treat runoff from the site covered by the application;

b.

No significant offsite impacts. The proposed land disturbing or land development activity is less than one acre in size and the village has determined the activity will have no significant impact on another property or on an environmentally sensitive area due to internal drainage or other site conditions that limit the potential impacts of runoff from the proposed activity; or

c.

Site conditions. It is impracticable to meet the requirement due to site conditions such as slopes, soils, proximity to existing structures or desirable trees, limited site dimensions, surrounding land uses, the potential for groundwater contamination, public health or safety problems, or other factors beyond the control of the applicant. No site shall be entitled to an exemption under this paragraph due solely to the size of the proposed land development activity in relation to the parcel size. However, the village engineer shall provide special consideration in granting exemptions under this paragraph for the following sites:

1.

Redevelopment sites.

2.

In-fill development areas less than one acre.

3.

Highway projects where limited public right-of-way land is available for the installation of storm water BMPs.

4.

Land developments with less than ten percent of the proposed disturbed area planned to be connected impervious surfaces and the total cumulative area of all impervious areas is less than one acre using the final build-out condition.

(2)

Application for exemption. An exemption under subsection (1) above may only be granted by the village board upon the applicant submitting the following items to the village engineer, which shall constitute a completed application:

a.

A written request describing the provisions of this subsection for which an exception is being requested and an explanation of why;

b.

A site plan in accordance with subsection (c) above, including the delineation of the area and size (in acres) to which the exemption would apply and any other storm water BMPs required to meet this division or as recommended in a regional storm water management plan;

c.

The necessary technical documentation to demonstrate that the site meets one or more of the criteria for which an exemption is being applied, including documentation of the applicable provisions of any regional storm water management plan that may be involved;

d.

For off-site BMP(s) under subsection 1.a. above:

1.

Documentation that the necessary BMP(s) have been properly installed, including as-built plans, construction certification and design summaries in accordance with section 34-108(d);

2.

A copy of the recorded maintenance agreement in accordance with section 34-112, and any other easements or legal arrangement that may be involved to ensure the long-term maintenance of the off-site BMP(s).

3.

Documentation of payment of any applicable fees that may be required by a unit of governmental charged with implementing a regional storm water management plan.

e.

Other materials that the village engineer determines to be necessary to make a determination under this subsection or to comply with this division.

(3)

Review procedure. The village engineer shall review all exemption application materials submitted under subsection (2) above, determine compliance with this section and notify the applicant of a decision within 20 working days of the submittal date, in accordance with the procedures under section 34-107(f) above. The village board shall approve all exemptions under subsection (1)c. above. In consideration of all exemption requests, the village engineer shall ensure that the applicant meets the requirements of this section to the maximum extent practicable.

(4)

Exemption fee. For those sites that are exempted under this subsection, and are not publicly funded, the applicant shall contribute funds to the village to be used exclusively for storm water BMP implementation or stream restoration expenses within the village. The amount of the payment shall be based on the average costs for the typical BMP(s) that would have been required on-site to comply with the requirements of this section had an exemption not been granted.

(5)

Appeal. If the applicant does not agree with any determination of the village under this subsection, the applicant may appeal the decision pursuant to the procedures in section 34-114(c).

(f)

Preliminary storm water management plan requirements. Preliminary storm water management plans shall contain the following applicable items:

(1)

Drafting date and contact information for the project engineer with all other mapping elements and scale consistent with the site plan map;

(2)

Delineation of existing and proposed watersheds, subwatersheds and major flow paths within the site and draining into the site from adjacent properties;

(3)

Location, type and preliminary design of proposed storm water BMPs needed to comply with this division;

(4)

Location and type of major storm water conveyance systems proposed for the site;

(5)

Existing and proposed storm water discharge points;

(6)

Location and preliminary dimensions of proposed drainage easements;

(7)

Location of soil borings and soil profile evaluations with surface elevations and unique references to supplemental data sheets, as needed to determine feasibility of any proposed storm water BMP and to comply with applicable BMP technical standards;

Note: The required location, depth and type of soil evaluations will depend on the storm water BMPs proposed for the site. In general, soil profile evaluations usually need to extend to a depth of 3-10 feet below the proposed bottom elevation of storm water BMPs. Refer to BMP technical standards for details.

(8)

Preliminary location of access lanes for maintenance of storm water BMPs;

(9)

Support documentation for the plan reviewer, including:

a.

A preliminary plan narrative describing site drainage, ultimate receiving water body for off-site discharges, major site restrictions, and how the preliminary storm water management plan will meet the requirements of this division and other objectives identified by the project engineer;

b.

Summary of watershed, subwatershed and land use data in acres and the preliminary results of any hydrology calculations;

c.

Soil profile evaluation data in accordance with BMP technical standards;

d.

Proposed ownership and maintenance responsibilities for all proposed storm water BMPs.

(g)

Final storm water management plan requirements. Final storm water management plans shall contain the following applicable items:

(1)

Drafting date and contact information for the project engineer, with all other mapping elements and scale consistent with the site plan map;

(2)

Location of existing and proposed storm water discharge points;

(3)

Delineation and labeling of all proposed impervious areas and accompanying area computations;

(4)

Final design drawings of all proposed storm water BMPs with unique references to support documentation, prepared in accordance with minimum village standards and of sufficient clarity for those responsible for site grading, including:

a.

Plan views showing the location of proposed BMPs in combination with the site plan map at a scale of one inch equals no more than 100 feet;

b.

Additional detail plan view drawings at a scale of one inch equals no more than 40 lineal feet, showing proposed two foot contours and all critical design features and elevations;

c.

Detailed cross-sections and profiles of each BMP showing all critical design features, side slopes, structures, soil profiles and applicable elevations, including highest groundwater table;

d.

Detailed drawings or material specifications for inlets or outlets.

(5)

Type, size, location and cross-sections of all pipes, open channels, grade stabilization structures and other proposed storm water conveyance systems, with unique references to support documentation;

(6)

Location and dimensions of proposed drainage easements;

(7)

Location, dimensions and surfacing material or soils data of proposed access lanes and delineation of easements needed to allow future maintenance of all storm water BMPs in accordance with section 34-112(b) below. The minimum width of any access easement shall be 15 feet;

(8)

Location of soil borings and soil profile evaluations with surface elevations and unique references to supplemental data sheets, as needed to determine feasibility of any proposed storm water BMP and to comply with applicable technical standards;

(9)

Detailed construction notes explaining all necessary procedures to be followed to properly implement the plan, including planting and landscaping specifications, timing and sequencing of construction and any temporary measures needed to protect BMPs during the construction phase;

(10)

A detailed stormwater BMP construction inspection plan, outlining the critical elements in the plan that need to be surveyed or inspected by a representative of the project engineer, the village engineer or the municipality, and the timing and notification requirements involved.

(11)

A final storm water BMP maintenance agreement in accordance with section 34-112;

(12)

Support documentation summarized in accordance with village standards, including but not limited to:

a.

A narrative summary of the storm water management plan, briefly explaining any unique information that led to the selection of BMPs, how the proposed plan meets the guiding principles under subsection (b) above, and the specific storm water planning requirements under subsection (d) above.

b.

Maps of existing and proposed watersheds, subwatersheds, Tc/Tt flow paths, soil types, hydrologic soil groups, land uses/cover type and accompanying runoff curve numbers within the site and draining into the site from adjacent properties, with unique references to hydrology data summaries and a description of the ultimate receiving water body(s) for off-site discharges;

c.

Pre-development and post-development hydrology and pollutant loading (if applicable) data for each watershed, such as peak flows and runoff volumes, as needed to meet the requirements of this division. All major assumptions used in developing input parameters shall be clearly stated and cross-referenced to the maps under subsection b. above;

d.

Impervious surface maps and calculations of runoff volumes and effective infiltration areas, in accordance with subsection (d)(3) above.

e.

Hydraulic and hydrologic data summaries for all existing and proposed pipes, open channels, grade stabilization structures and other storm water conveyance systems, and the necessary documentation to demonstrate compliance with the site drainage requirements under subsection (d)(6) above.

f.

BMP design data for each proposed BMP, showing how it complies with applicable technical standards and the requirements of this division;

g.

Soil evaluation reports, following the standards in section 34-111(e), with matching references to map features showing their location and elevations;

h.

A cover sheet stamped and signed by a professional engineer registered in the State of Wisconsin indicating that all plans and supporting documentation have been reviewed and approved by the engineer and certifying that they have read the requirements of this division and that, to the best of their knowledge, the submitted plans comply with the requirements.

i.

Cost estimates for the installation of proposed storm water BMPs, which shall serve as a basis for the financial assurance under section 34-108(c) above. The applicant may use average costs for BMP installations in the village rather than specific estimates, upon approval by the village engineer.

j.

For sites where changes are proposed in storm water flow paths, or where proposed storm water discharges may otherwise have a significant negative impact on downstream property owner(s), the village engineer may require the applicant to submit written authorization or complete other legal arrangements with the affected property owner(s); and

(13)

Other items deemed necessary by the village to ensure compliance with the requirements of this section.

(Ord. No. 816, § IV, 1-6-09; Ord. No. 914, § VI, 5-17-16; Ord. No. 928, § VI, 4-18-17)