(1) DEFINITIONS. In
this section:
(a) "Average annual rainfall"
means the rainfall determined by the following year and location for the
location nearest the project site: Madison, 1981 (Mar. 12-Dec. 2); Green Bay,
1969 (Mar. 29-Nov. 25); Milwaukee, 1969 (Mar. 28-Dec. 6); Minneapolis, 1959
(Mar. 13-Nov. 4); Duluth, 1975 (Mar. 24-Nov. 19).
(b) "TR-55" means the United States
Department of Agriculture, Natural Resources Conservation Service (formerly
Soil Conservation Service), Urban Hydrology for Small Watersheds, Second
Edition, Technical Release 55, June 1986, or Technical Release 55 for Windows
(Win TR-55), 2002.
Note: TR-55 is on file with the offices of the Legislative
Reference Bureau, the Secretary of State, and the Department of Transportation,
Office of General Counsel. Copies may be obtained by writing to the U.S.
Department of Agriculture, Natural Resources Conservation Service, Conservation
Engineering Division, 14th and Independence Avenue, SW., Room 6136-S,
Washington, DC 20250. The phone number for the division is: 202-720-2520, and
the fax number is: 202-720-0428. TR-55 is available electronically at:
ftp://ftp.wcc.nrcs.usda.gov/wntsc/H&H/other/TR55documentation.pdf
(2) PLAN. The
department shall develop and implement a written plan that includes the
requirements of subs. (3) to (10) for each transportation facility. This plan
may be part of the erosion control plan.
(3) TOTAL SUSPENDED SOLIDS. Best management
practices shall be designed, installed and maintained to control total
suspended solids carried in runoff from the transportation facility as follows:
(a) For transportation facilities first
constructed on or after January 1, 2003 by design, reduce the suspended solids
load to the maximum extent practicable, based on an average annual rainfall, as
compared to no runoff management controls. A reduction in total suspended
solids by at least 80% meets the requirements of this paragraph.
(b) For highway reconstruction and
non-highway redevelopment, by design, reduce to the maximum extent practicable
the total suspended solids load by at least 40%, based on an average annual
rainfall, as compared to no runoff management controls. A 40% or greater total
suspended solids reduction shall meet the requirements of this paragraph. In
this paragraph, "redevelopment" means the construction of residential,
commercial, industrial or institutional land uses and associated roads as a
substitute for existing residential, commercial, industrial or institutional
land uses.
(c) Notwithstanding
pars. (a) and (b), if the design cannot achieve the applicable total suspended
solids reduction specified, the design 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.
(4) PEAK DISCHARGE.
(a) By design, BMPs shall be employed to
maintain or reduce the peak runoff discharge rates, to the maximum extent
practicable, as compared to pre-development site conditions for the 2-year
24-hour design storm or to the 2-year design storm with a duration equal to the
time of concentration applicable to the transportation facility.
Pre-development conditions shall assume "good hydrologic conditions" for
appropriate land covers as identified in TR-55 or an equivalent methodology.
The meaning of "hydrologic soil group" and "runoff curve number" are as
determined in TR-55. However, when pre-development land cover is cropland,
rather than using TR-55 values for cropland, the runoff curve numbers in Table
2 below shall be used.
TABLE 2
Maximum Pre-Development Runoff Curve Numbers for
Cropland Areas
Hydrologic Soil Group
|
A
|
B
|
C
|
D
|
Runoff Curve Number
|
56
|
70
|
79
|
83
|
Note: The curve numbers in Table 2 represent mid-range values
for soils under a good hydrologic condition where conservation practices are
used and are selected to be protective of the resource waters.
(b) This subsection does not apply
to:
1. A transportation facility where the
change in hydrology due to development does not increase the existing surface
water elevation at any point within the downstream receiving surface water by
more than 0.01 of a foot for the 2-year 24-hour storm or for a 2-year design
storm with a duration equal to the time of concentration.
Note: Hydraulic models, such as HEC-2 or an equivalent
methodology, may be used to determine the change in surface water
elevations.
2. A highway
reconstruction site.
(5) INFILTRATION.
(a) Except as provided in pars. (d) to (g),
BMPs shall be designed, installed and maintained to infiltrate runoff to the
maximum extent practicable in accordance with one of the following:
1. Infiltrate sufficient runoff volume so
that the post-construction infiltration volume shall be at least 60% of the
pre-construction 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.
2. Infiltrate
10% of the post-development runoff volume from the 2-year 24-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.
(b) Pre-development condition shall be the
same as specified in sub. (4) (a).
(c) 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 in accordance with par. (g). Pretreatment may include, but
is not limited to, oil and grease separation, sedimentation, biofiltration,
filtration, swales or filter strips.
Note: 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) The following are prohibited from meeting
the requirements of this subsection, due to the potential for groundwater
contamination:
1. Areas associated with tier 1
industrial facilities identified in s.
NR 216.21(2)
(a), including storage, loading, rooftop and
parking.
2. Storage and loading
areas of tier 2 industrial facilities identified in s.
NR 216.21(2)
(b).
Note: Runoff from tier 2 parking and rooftop areas may require
pretreatment before infiltration.
3. Fueling and vehicle maintenance
areas.
4. Areas within 1000 feet
upgradient or within 100 feet downgradient of karst features.
5. Areas with less than 3 feet separation
distance from the bottom of the infiltration system to the elevation of
seasonal high groundwater or the top of bedrock.
6. Areas with runoff from industrial,
commercial and institutional parking lots and roads and residential arterial
roads with less than 5 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 well serving a community water system as specified in ch. NR 811 or within
100 feet of a well serving a non-community or private water system as specified
in ch. NR 812 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 s.
NR
720.03(2), are present in the soil
through which infiltration will occur.
9. Any area where the soil does not exhibit
any of the following characteristics between the bottom of the infiltration
system and seasonal high groundwater and top of bedrock:
a. At least a 3-foot soil layer with 20
percent fines or greater. In this subdivision paragraph, "percent fines" means
the percentage of a given sample of soil, which passes through a #200
sieve.
b. At least a 5-foot soil
layer with 10 percent fines or greater. In this subdivision paragraph, "percent
fines" means the percentage of a given sample of soil, which passes through a
#200 sieve.
c. Where the soil
medium within the infiltration system does not filter pollutants from water at
least as effectively as the soils described in subd. 9. a. or b.
(e) Projects undertaken
in the following areas are not required to meet the requirements of this
subsection:
1. Areas where the infiltration
rate of the soil is less than 0.6 inches/hour measured at the bottom of the
infiltration system.
2. Parking
areas and access roads less than 5,000 square feet for commercial and
industrial development.
3. Areas in
which a new project is replacing existing residential, commercial, industrial
or institutional land uses or associated roads, or both.
4. Undeveloped areas of less than 5 acres
located within existing urban sewer service areas and surrounded by existing,
residential, commercial, industrial or institutional land uses.
5. Any area during periods when the soil at
that area is frozen.
6. Roads in
commercial, industrial and institutional land uses, and arterial residential
roads.
7. Highways.
(f) 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.
(g)
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 as determined under ch. NR 140. However, if
specific information indicates that compliance with a preventive action limit
is not achievable at that location, then the infiltration system may not be
installed or shall be modified to prevent infiltration to the maximum extent
practicable.
2. Notwithstanding
subd. 1., the discharge from BMPs shall remain below the enforcement standard
at the point of standards application, as determined under ch. NR
140.
(6)
BUFFER AREAS.
(a) In this subsection, "buffer
area" means an area of land that commences at the ordinary high-water mark of
lakes, streams and rivers, or at the delineated boundary of wetlands, and that
is the greatest of the following applicable widths, as measured horizontally
from the ordinary high-water mark or delineated wetland boundary:
1. For outstanding resource waters and
exceptional resource waters, and for wetlands in areas of special natural
resource interest as specified in s.
NR
103.04, 75 feet.
2. 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.
3. For lakes, 50 feet.
4. 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 delineation shall be made in accordance with s.
NR
103.08(1m). This paragraph does not
apply to wetlands that have been completely filled in accordance with all
applicable state and federal regulations. The buffer 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.
5. For less
susceptible wetlands, 10 percent 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.
6. For concentrated flow channels with
drainage areas greater than 130 acres, 10 feet.
(ag) In par. (a) 1., 4. and 5.,
determinations of the extent of the buffer 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 s.
NR
103.03.
(am) In this subsection, "buffer 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.
(b)
1. Beginning with land acquired on or after
January 1, 2003 for a transportation facility, no impervious surface that is
part of a transportation facility may be constructed within a buffer area,
unless the department determines, in consultation with the department of
natural resources, that there is no practical alternative. If there is no
practical alternative to locating an impervious part of a transportation
facility within a buffer area, the transportation facility may be constructed
in the buffer area only to the extent the department, in consultation with the
department of natural resources, determines is reasonably necessary, and the
department shall state in the erosion control plan or in the plan prepared
under sub. (2) why it is necessary to construct the transportation facility
within a buffer area.
2. If a
transportation facility is constructed within a buffer area, adequate sod or
self-sustaining vegetative cover, such as grasses, forbs, sedges and duff
layers of leaves and woody debris, of 70% or greater shall be established and
maintained in the area that is the width of the buffer area, or the greatest
width practical, and throughout the length of the buffer area in which the
transportation facility is located. The adequate sod or self-sustaining
vegetative cover required under this subdivision 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.
Note: Vegetative cover may be measured using the line transect
method described in the University of Wisconsin-Extension publication number
A3533, titled "Estimating Residue Using the Line Transect Method". Seeding of
non-aggressive vegetative cover is recommended in the buffer areas. Vegetation
that is flood and drought tolerant and that has an extensive root system is
preferable.
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 buffer area.
4. This
subsection does not apply to:
a. Areas in
which a new project, other than a highway, is replacing existing residential,
commercial, industrial or institutional land uses.
b. Transportation facilities that cross or
access surface waters, such as boat landings, bridges and culverts.
c. Transportation facilities from which
runoff does not enter the surface water, except to the extent that vegetative
ground cover is necessary to maintain bank stability.
(7) FUELING AND VEHICLE
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.
(8) LOCATION AND REGIONAL TREATMENT
EXCLUSION.
(a) BMPs may be located on a
project site, or off a project site as part of a regional storm water device,
practice or system.
(b) Runoff
within a non-navigable surface water that flows into a BMP, such as a wet
detention pond, is not required to meet the performance standards of this
section. Permanent BMPs may be located in non-navigable surface
waters.
(c) Except as provided in
par. (d), post-construction runoff from a transportation facility first
constructed after January 1, 2003 shall meet the requirements of this section
before entering a 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 requirements of this section if all of the following
apply:
1. The BMP was constructed prior to
January 1, 2003 and the BMP either received a permit issued under ch. 30,
Stats., or the BMP did not require a ch. 30, Stats., permit.
2. The BMP is designed to treat runoff from
upland development that is constructed after the BMP was constructed.
(e) The discharge of runoff from a
BMP, such as a wet detention pond, is subject to this chapter.
(9) TIMING. The BMPs required
under this section shall be installed before the project site has undergone
final stabilization.
(10) SWALE
TREATMENT.
(a) Except as provided in par. (b),
transportation facilities that use swales for runoff conveyance and pollutant
removal satisfy all of the requirements of this section, if the swales are
designed to the maximum extent practicable to do all of the following:
1. Be vegetated. However, where appropriate,
non-vegetative measures may be employed to prevent erosion or provide for
runoff treatment, such as rock riprap stabilization or check dams.
Note: It is preferred that tall and dense vegetation be
maintained within the swale due to its greater effectiveness at enhancing
runoff pollutant removal.
2. 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 based on a 2-year 24-hour design storm or on a 2-year design
storm with a duration equal to the time of concentration. If a swale of 200
feet in length cannot be designed with a flow velocity of 1.5 feet per second
or less, the flow velocity shall be reduced to the maximum extent practicable.
Note: The swale design may include check dams to slow runoff
flows and improve pollutant removal. Transportation facilities with continuous
features such as curb and gutter, sidewalks or parking lanes do not comply with
the design requirements of this subsection. However, a limited amount of
structural measures such as curb and gutter may be allowed as necessary to
account for other concerns such as human safety or resource protection.
(b) Notwithstanding
par. (a), the department shall consult with the department of natural
resources' liaison to the department of transportation to determine whether
other provisions of this section are necessary to achieve water quality
standards. This paragraph applies only to a transportation facility that has an
average daily traffic of 2,500 or more, and from which the initial surface
water of the state that runoff from the transportation facility directly enters
is any of the following:
1. An outstanding
resource water.
2. An exceptional
resource water.
3. Waters listed in
section 303(d) of the federal Clean Water Act,
33 USC
1344, as amended, that are identified as
impaired in whole or in part, due to nonpoint source impacts.
4. Waters for which targeted performance
standards are promulgated under s.
NR
151.004.