Chapter 14.08
GENERAL PROVISIONS
Sections:
14.08.030 Stormwater management plan and facilities required.
14.08.070 Site-specific stormwater management plan content.
14.08.010 Jurisdiction.
The jurisdiction of the ordinance codified in this Title 14 shall include all lands or waters within the corporate limits of the city of Brookfield. (Ord. 1749 § 1 (part), 2000)
14.08.020 Illicit discharges.
No person shall discharge, spill or otherwise deposit substances or materials that are not entirely composed of stormwater into receiving bodies of surface water, storm sewers or other drainage facilities, or onto driveways, sidewalks, parking lots, or other impervious or pervious areas that drain into the streams and watercourses of the area. No person shall connect a building wastewater sewer or drain to storm sewers or other stormwater drainage facilities. The following discharges are exempt from the provision of this Title 14:
A. Discharge authorized by a permit issued by the Wisconsin Department of Natural Resources;
B. Discharges resulting from fire fighting activities;
C. Discharges from uncontaminated ground water, potable water sources, roof drains, foundation drains, and foundation drain sump pump discharges, air conditioning condensation, lawn watering, water main and hydrant flushing, and swimming pools, if the pool water has been dechlorinated;
D. Discharges from individual automobile washing by automobile owners;
E. Agricultural activities, such activities, however, being subject to good soil and water conservation practices; and
F. Facility maintenance activities undertaken by any federal, state, county or municipal agency, such activities, however, being subject to construction erosion control measures. (Ord. 2112-07 § 2, 2007; Ord. 1749 § 1 (part), 2000)
14.08.030 Stormwater management plan and facilities required.
No person shall proceed with any residential, commercial, industrial or institutional land use development or redevelopment, or with the land division of property, without providing appropriate stormwater management facilities that adequately control stormwater runoff from such development or redevelopment or subdivided property. A site-specific stormwater management plan must be submitted and approved by the city before any required new stormwater management facilities are constructed, unless exempted or waived pursuant to the provisions of this Title 14. An approved site-specific stormwater management plan is also required before an existing drainage system is relocated, deepened, widened, enlarged, filled, obstructed or otherwise altered in preparation for land use development and redevelopment or land division of property. The plan must be submitted and approved before any land use development and redevelopment is commenced or a land subdivision plat or certified survey map approved and recorded. (Ord. 1749 § 1 (part), 2000)
14.08.040 Applicability.
This Title 14 applies to land use development, redevelopment and land division activities that meet the following criteria:
A. Residential land use development, redevelopment or land division occurring within a gross aggregate area of five acres or more;
B. Residential land use development or redevelopment occurring within a gross aggregate area of three acres or more, if 1.5 acres or more of additional impervious surfaces are proposed;
C. Nonresidential land use development, redevelopment or land division occurring within a gross aggregate area of 1.5 acres or more if 0.5 acres or more of additional impervious surfaces are proposed; and
D. Land use development, redevelopment, or land division of any size area that in the opinion of the city is likely to result in stormwater runoff which exceeds the safe capacity of existing drainage facilities or receiving watercourse; which causes undue channel erosion; which increases surface water pollution; or which endangers property or public health and safety.
E. Land use development, redevelopment or land division that meets the criteria of Chapter 13 of the Milwaukee Metropolitan Sewerage District Rules on Surface Water and Stormwater Runoff Management.
F. Any land use development, redevelopment or land division which adds or subtracts impervious surface area less than the thresholds listed herein. Such changes will be processed as a minor stormwater management plan unless the total impervious surface area of the addition and the existing development meets one of the above thresholds. (Ord. 2440-15 § 8, 2015; Ord. 2112-07 § 3, 2007; Ord. 1902 § 3, 2003; 1749 § 1 (part), 2000)
14.08.050 Exemptions.
The following development and redevelopment activities are exempt from the requirements of this Title 14:
A. Maintenance, alteration, improvement or use of existing structure which does not significantly affect the water quality or hydrologic and hydraulic conditions of the surface water resources of the sub-watershed concerned as determined by the city;
B. Maintenance activities undertaken by any federal, state or municipal governmental agency;
C. Stormwater management facilities to be constructed or measures to be undertaken by the city when the city has determined that a stormwater management plan is not required; and
D. Agricultural activities not associated with development and redevelopment. (Ord. 1749 § 1 (part), 2000)
14.08.060 Waivers.
The city may waive the requirements of this Title 14 in part or in whole. A request for waiver shall be submitted to the city on an application provided by the city and shall include a narrative description and drawings of the proposed development or redevelopment or land division for which the waiver is being requested. Based on the above application, the city may grant a waiver if the city finds that the development or redevelopment or land division is not likely to:
A. Significantly increase the rate or volume of stormwater runoff from the development, redevelopment or land division site;
B. Have a significant adverse impact on a wetland or other environmentally sensitive area;
C. Significantly contribute to the degradation of surface or ground water quality;
D. Otherwise significantly impair attainment of the purpose of this Title 14; or
E. The applicable, adopted stormwater management system plan does not indicate the need for any site-specific stormwater management measures on the site concerned.
The city may choose to consult with other agencies, DNR, Army Corps. of Engineers or consulting engineers regarding waiver determination. (Ord. 1749 § 1 (part), 2000)
14.08.070 Site-specific stormwater management plan content.
The site-specific stormwater management plan required by this Title 14 shall meet the following requirements:
A. General.
1. The stormwater management plan shall be prepared by a professional engineer registered in the state of Wisconsin and shall contain all of the information required to evaluate the adequacy of the plan and the probable impacts of implementation of the plan on the quality and quantity of stormwater discharges, on existing drainage facilities, and on surface and ground water quality. The plan shall contain the name, address and telephone number of the owner or developer of the site concerned; of the registered professional engineer preparing the plan; of the person responsible for installation of the stormwater management facilities recommended in the plan; and of the person responsible for the maintenance of those facilities. All pertinent information shall be provided on an application available from the city.
2. The plan shall consist of narrative descriptions and explanations; maps, charts and graphs; tables; photographs; supporting calculations; and references to recognized engineering text and manuals as may be necessary to provide a clear and concise description of the plan. The sources of maps and data presented in the plan shall be identified.
B. Existing Site Conditions. The plan shall include a map and description of the existing conditions of the site concerned including:
1. A map of the site at a scale of one inch equals one hundred (100) feet or larger showing the property boundaries referenced to the U. S. Public Land Survey system or to a lot and block of a recorded subdivision plat; the topography of the site including contours shown at an interval of two feet or less, together with such spot elevations as may be necessary; the contours and spot elevations shall be referenced to the National Geodetic Vertical Datum of 1929;
2. The hydrologic and hydraulic characteristics of the site including drainage flow paths and directions of flow onto, through and out of the site; related drainage basin boundaries; times of concentration; and rates and volumes of flow;
3. The location of areas where stormwater may collect or percolate into the ground;
4. Ground water elevations referred to the National Geodetic Vertical Datum of 1929;
5. Soils by hydrologic group;
6. Cover type and condition;
7. Location and extent of impervious surfaces, including type and condition of the surfaces;
8. Locations and outlines of all buildings or other structures;
9. Location of all receiving bodies of surface water on or within one hundred (100) feet of the site into which stormwater flows;
10. Location and extent of the one hundred (100) year recurrence interval flood hazard area associated with any perennial stream or watercourse on or within one hundred (100) feet of the site;
11. Information regarding current water quality objectives and current water quality conditions in any perennial watercourses located on or within one hundred (100) feet to the site;
12. Locations of stormwater runoff discharge points from adjacent tributary areas together with the size of those areas expressed in acres;
13. Locations, sizes and elevations of all existing storm sewers, channels, ditches, detention or retention ponds, or other engineered drainage facilities on or within one hundred (100) feet of the site; the elevations being referred to the National Geodetic Datum of 1929;
14. Locations of any existing water supply wells and wellhead protection areas; and
15. Locations and size of wetlands on or within one hundred (100) feet of the site.
C. Proposed Post-Development and Redevelopment Site Conditions. The plan shall describe the alterations proposed to be made to the site and the resulting proposed post-development and redevelopment conditions. The description shall include:
1. Proposed changes in the planimetry of the site and in the topography of the site by contours having the same contour interval and referred to the same datum as used to present the topography of the existing site conditions;
2. The location and outline of all proposed buildings or other structures;
3. Changes in the location, extent and type of impervious surfaces;
4. The location and extent of areas where vegetation is to be disturbed or planted;
5. Changes in the drainage flow paths into, through and out of the site, and related changes in drainage basin boundaries;
6. The location, elevations and sizes of all proposed minor and major stormwater management facilities; the former including all storm sewers and inlets, and the latter including curbed roadways, roadway ditches, culvert, storage facilities and interconnected flow paths; all elevations being referred to the National Geodetic Vertical Datum of 1929;
7. Any changes to lakes, streams, watercourses or wetlands on or within one hundred (100) feet of the site concerned; and
8. The location and widths of required public rights-of-way or easements needed to accommodate the recommended stormwater management facilities.
D. Anticipated Impacts. The plan shall contain a description of the following anticipated impacts of stormwater runoff from the proposed development, redevelopment or land division as managed by the facilities and measures recommended in the plan:
1. Increases or decreases in the rates and volumes of stormwater runoff;
2. Changes in the locations and conveyance capacities of stormwater discharge points from and to the site concerned;
3. Adequacy of receiving storm sewer, engineered stormwater management facility or watercourse to convey or store the anticipated peak rate of stormwater discharge from the site concerned, giving due consideration to existing flows;
4. Changes in the location and extent of the one hundred (100) year recurrence interval flood hazard area of any perennial watercourse location within, through or within one hundred (100) feet of, the site concerned;
5. Changes in the quality of receiving wetlands and bodies of surface water;
6. Changes in ground water elevations referred to National Geodetic Vertical Datum of 1929; and
7. Impacts on municipal wellhead protection areas.
E. Proposed Stormwater Management Facilities and Measures. The plan shall include a definitive description of the stormwater management facilities and measures proposed to be used for the control of the quantity and quality of the anticipated stormwater runoff from the proposed development, redevelopment, or land division. The measures and descriptions may include:
1. For detention and retention facilities: locations, areas, depths, volumes, inlet and outlet configurations, and elevation of the bottoms, and of key inlet and outlet control structures; all elevations being referred to National Geodetic Vertical Datum of 1929. Detention pond landscaping must follow the most recent edition of the city of Brookfield’s “Stormwater Detention/Retention Basin Landscape Guidelines”;
2. For conveyance facilities: locations of inlets and manholes and associated rim and invert elevations and pipe sizes, slope and materials; locations, elevations and cross sections of ditches, swales and channels; and culvert sizes, inlet and outlet configurations and elevations; all elevations being referred to National Geodetic Vertical Datum of 1929;
3. Areas to be used for percolation into the ground water reservoir;
4. Provisions for the control of erosion and sedimentation; including control of off-site impacts; and
5. Measures to abate any potential pollution of surface and ground waters.
F. Hydrologic Computations. The plan shall include computations of peak flow rates and discharge volumes for the SEWRPC Recommended Design Rainfall Depths for Southeastern Wisconsin Region two-year (fifty (50) percent probability), ten-year (ten percent probability), and one hundred (100) year (one percent probability) recurrence interval rainfall events for each point of discharge into and out of the site concerned under existing and planned development and redevelopment conditions. The data shall include times of concentration to key junctions in flow paths and to points of discharge into and out of the site, the hydrologic soil group and the drainage area’s curve number.
G. Construction Schedule and Costs. The plan shall include a schedule for the construction of the recommended stormwater management facilities and estimates of attendant capital and operation and maintenance costs.
H. Any other requirements of Chapter 13 of the Milwaukee Metropolitan Sewerage District Rules on Surface Water and Stormwater Runoff Management. (Ord. 2112-07 § 4, 2007; Ord. 1902 § 4, 2003; 1749 § 1 (part), 2000)