The provisions and regulations of Ch. 62, Wis. Stats., and Chs.
NR 281, NR 283 and NR 151, Wis. Adm. Code, adopted by the Wisconsin
Department of Natural Resources are hereby made a part of this chapter
by reference, and shall extend over and govern all of the stormwater
management systems installed, maintained, altered or repaired in the
City of Reedsburg.
The City Engineer and Building Inspector or their designee shall
administer, direct and enforce the provisions of this chapter.
This chapter shall apply to all land disturbing activities greater
than one acre and land disturbing activities of less than one acre
which are adjacent to the FEMA-designated floodplain or the City's
primary north-to-south storm drainageways or adjacent to Babb Creek,
and said land disturbing activities will impact stormwater flow to
or in said floodplain, drainageway or Babb Creek; provided, however,
for the following exemptions and exclusions:
A. Erosion control exemptions.
(1) Nonpoint discharges from agricultural facilities and practices.
(2) Nonpoint discharges from silviculture activities.
(3) Routine maintenance for project sites of under one acre of land disturbance
if performed to maintain the original line and grade, hydraulic capacity
or original purpose of the facility.
B. Stormwater discharge/detention exemptions:
(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
one acre.
(3) Agricultural facilities and practices.
(5) 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.
C. Stormwater infiltration exclusions:
(1) Areas associated with tier-one industrial facilities identified in
§ NR 216.21(2)(a), Wis. Adm. Code, including storage, loading,
rooftop and parking.
(2) Storage and loading areas of tier-two industrial facilities identified
in § NR 216.21(2)(b), Wis. Adm. Code. Runoff from tier-two
parking and rooftop areas may be infiltrated, but may require pretreatment.
(3) Fueling and vehicle maintenance areas.
(4) Areas within 1,000 feet upgradient or within 100 feet downgradient
of karst features.
(5) 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. This does not prohibit infiltration of roof
runoff.
(6) 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.
(7) 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.
(8) 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.
(9) 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 does not prohibit infiltration of roof runoff.
D. Stormwater infiltration exemptions:
(1) Areas where the infiltration rate of the soil is less than 0.6 inches/hour
measured at the site.
(2) Parking areas and access roads less than 5,000 square feet for commercial
and industrial development.
(3) Redevelopment post-construction sites.
(4) In-fill development areas less than five acres.
(5) Infiltration areas during periods when the soil on the site is frozen.
(6) Roads in commercial, industrial and institutional land uses, and
arterial residential roads.
All land disturbing activities governed by this chapter shall
model the peak flows using TR-55 methods and infiltration rates using
SLAMM, P8 or an equivalent program:
A. Peak discharge management design.
(1) By design, BMPs shall reduce the two-, five-, ten-, twenty-five-,
fifty- and 100-year, twenty-four-hour storm post-developed peak discharges
to predeveloped levels.
(2) Predevelopment conditions shall assume good hydrologic conditions
for appropriate land covers as identified in TR-55. However, when
predevelopment land cover is cropland, the runoff curve numbers in
Table 1 shall be used.
Table 1
Maximum Predevelopment Runoff Curve Numbers for Cropland
Areas
|
---|
Hydrologic Soil Group
|
A
|
B
|
C
|
D
|
Runoff Curve Number
|
56
|
70
|
79
|
83
|
(3) Post-development conditions shall assume good hydrologic conditions
for appropriate land covers as identified in TR-55.
(4) The BMP shall be designed to release peak flows at a safe rate for
the two-, five-, ten-, twenty-five-, fifty- and 100-year, twenty-four-hour
storm events.
B. Infiltration design.
(1) BMPs shall be designed, installed, and maintained to infiltrate runoff
to the maximum extent practicable.
(2) For residential developments, one of the following shall be met:
(a)
Post-development infiltration volume shall be at least 90% of
the predevelopment infiltration volume, based on an average annual
rainfall. 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 event. 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. No more than
1% of the project site is required as an effective infiltration area.
C. For nonresidential development, including commercial, industrial
and institutional development, one of the following shall be met:
(1) Post-development infiltration volume shall be at least 60% of the
predevelopment infiltration volume, based on an average annual rainfall.
No more than 2% of the project site is required as an effective infiltration
area.
(2) Infiltrate 10% of the runoff from the two-year, twenty-four-hour
design storm. 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. No more than 2% of the project site is
required as an effective infiltration area.
D. Before infiltrating runoff, pretreatment shall be required for parking
lot runoff and for runoff from new road construction in 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. Pretreatment options may include, but are not
limited to, oil/grease separation, sedimentation, biofiltration, filtration,
swales or filter strips.
All land disturbing activities that are governed by this chapter
shall have a stormwater management plan. The stormwater management
plan shall contain, at a minimum, the following information:
A. Name, address, and telephone number for the following:
(3) Stormwater management designer.
(4) Contractor responsible for installation of stormwater management
practices.
(5) Responsible party for reporting, monitoring, maintaining and repairing
stormwater management facilities during construction.
(6) Responsible party for reporting, monitoring, maintaining and repairing
stormwater management facilities post-construction.
B. A legal description of the property to be developed and street address
if applicable.
C. Predevelopment site conditions map(s), including:
(1) A scaled map with North arrow.
(3) The property boundary, rights-of-way and easements.
(4) Predominant soil types and hydrologic soil groups.
(5) Predeveloped cover type and condition.
(6) Watershed boundaries used in hydrology determinations.
(7) Existing two-foot contour interval or less.
(8) Topography and drainage patterns, including enough of the contiguous
properties to show runoff patterns onto, through, and from the site.
(9) Watercourses that may affect or be affected by runoff from the site.
(10)
Rivers, ponds, streams, wetlands, channels, ditches, and other
watercourses on and immediately adjacent to the site.
(11)
Limits of the 100-year floodplain.
(12)
Location of wells and wellhead protection areas adjacent to
the site.
(13)
Limits of land disturbing activities.
(14)
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).
D. Post-development site conditions map(s) including:
(1) A scaled map with North arrow.
(3) The property boundary, rights-of-way and easements.
(4) Predominant soil types and hydrologic soil groups.
(5) Predeveloped cover type and condition.
(6) Watershed boundaries used in hydrology determinations.
(7) Proposed two-foot contour interval or less.
(8) Topography and drainage patterns, including enough of the contiguous
properties to show runoff patterns onto, through and from the site.
(9) Watercourses that may affect or be affected by runoff from the site.
(10)
Rivers, ponds, streams, wetlands, channels, ditches, and other
watercourses on and immediately adjacent to the site.
(11)
Limits of the 100-year floodplain.
(12)
Location of wells and wellhead protection areas adjacent to
the site.
(13)
Limits of land disturbing activities.
(14)
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).
E. Stormwater management map(s), including:
(1) A scaled map with North arrow.
(3) The proposed property boundary, rights-of-way and easements.
(4) Proposed two-foot contour interval or less.
(5) Topography, including enough of the contiguous properties to show
runoff patterns onto, through, and from the site.
(6) Watercourses that may affect or be affected by runoff from the site.
(7) Rivers, ponds, streams, wetlands, channels, ditches, and other watercourses
on and immediately adjacent to the site.
(8) Limits of the 100-year floodplain.
(9) Location of wells and wellhead protection areas adjacent to the site.
(10)
Limits of land disturbing activities.
(11)
BMP detail information such as location, storage volume, size,
bottom elevation, overflow elevation, outlet structure, top of berm
elevation and all other information required to determine that the
BMP was adequately sized.
F. Hydrology 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).
G. 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.
H. A description and installation schedule for the stormwater management
practices needed to meet the performance standards.
I. A maintenance plan developed for the life of each stormwater management practice as stated in §
530-9D.
J. Cost estimates for the construction, operation, and maintenance of
each stormwater management practice.
K. Other information requested, in writing, by the City Engineer or
City Engineer's designee to determine compliance of the proposed stormwater
management measures with the provisions of this chapter.
L. All site investigations, plans, designs, computations, and drawings
shall be certified by a licensed professional engineer to be prepared
in accordance with accepted engineering practice and requirements
of this chapter.
All land disturbing activities that are governed by this chapter
shall be required to reduce erosion during construction and post-construction:
A. Erosion control during construction. By design, BMPs shall reduce
the sediment load in runoff by 80%.
B. Post-construction erosion and sediment control:
(1) For new development, by design, reduce the total suspended solids
load by 80% based on the average annual rainfall, as compared to no
runoff management controls.
(2) For redevelopment, by design, reduce the total suspended solids load
by 40% based on the average annual rainfall, as compared to no runoff
management controls.
(3) For in-fill development under five acres that occurs within 10 years
after the effective date of this chapter, by design, reduce the total
suspended solids load by 40% based on an average annual rainfall,
as compared to no runoff management controls.
(4) For in-fill development that occurs 10 or more years after the effective
date of this chapter, by design, reduce the total suspended solids
load by 80% based on an average annual rainfall, as compared to no
runoff management controls.
(5) Notwithstanding Subsection
B(1) to
(4), if the design cannot achieve the applicable total suspended solids reduction specified, the erosion control 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.
(6) Wisconsin Department of Natural Resources has created Conservation
Practice Standards which shall be used to design BMPs.
All land-disturbing activities that are governed by this chapter
shall submit a written erosion control plan with accompanying drawings
and supporting engineering data which shall contain, at a minimum,
the following information:
A. Name, address, and telephone number for the following:
(3) Erosion control designer.
(4) Contractor responsible for installation of erosion control practices.
(5) Responsible party for reporting, monitoring, maintaining and repairing
erosion control measures during construction.
(6) Responsible party for reporting, monitoring, maintaining and repairing
erosion control measures post-construction.
B. A legal description of the property to be developed and street address,
if applicable.
C. A description and installation schedule for the erosion control practices
needed to meet the performance standards.
D. A maintenance plan developed for erosion control practice, including
the required maintenance activities and maintenance activity schedule.
E. Cost estimates for the construction, operation, and maintenance of
each permanent erosion control structure.
F. Other information requested, in writing, by the City Engineer to
determine compliance of the proposed stormwater management measures
with the provisions of this chapter.
G. All site investigations, plans, designs, computations, and drawings
shall be certified by a licensed professional engineer to be prepared
in accordance with accepted engineering practice and requirements
of this chapter.
Any person who shall violate any provision of this chapter or who shall fail to obtain a permit as required hereunder shall be subject to a penalty as provided in Chapter
1, General Provisions, §
1-3, of the Code of the City of Reedsburg.