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The MPCA is conducting webinars to share the many updates to the Minnesota Stormwater Manual. The first webinar, on Dec. 15, covered infiltration practices; to see it, go to the Stormwater Manual webinar page.
The next webinar on Wednesday, Jan, 25, 1:30 to 3:00 p.m., will cover stormwater and rainwater harvest and
use/reuse. To access this webinar and see other future webinars, go the events page in the Stormwater Manual.
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In 2009, the Minnesota Legislature
directed the Minnesota Pollution Control Agency to “develop performance standards, design standards,
or other tools to enable and promote the implementation of low impact
development and other stormwater management techniques.” "Low impact
development" means an approach to stormwater management that mimics a site's
natural hydrology as the site is developed. With low impact development,
stormwater is managed on site, and the rate and volume of stormwater that reaches
receiving waters is unchanged by the development.
The MPCA,
with the support of a diverse group of stakeholders, spent three
years creating Minimal Impact Design Standards (MIDS) for designers, engineers,
planners, contractors, stormwater managers, and others involved in development
projects that may generate stormwater runoff. MIDS are low-impact development
standards, approaches, and credits that can be applied in communities around
the state. The concepts behind MIDS can be used by all Minnesotans; we can all
do our part in minimizing stormwater runoff and pollution.
Using low-impact
development approaches can reduce the amount of pollution reaching our lakes,
rivers, and streams and help recharge groundwater resources. MIDS tools also help
quantify these reductions in runoff and pollutant loading. MIDS helps
communities measure progress toward water and natural resource protection and
restoration goals, and will serve as the highest stormwater standard for
Minnesota Green Step Cities.
A MIDS Community
Assistance Package provides ordinances and tools, including the MIDS
performance goals and calculator (see below), that help local governments achieve
MIDS performance goals for stormwater. The package includes instructions, training
materials, and descriptions of implementation in several pilot communities. More
than 40 of Minnesota’s regulated MS4s report adopting MIDS to meet Minimum
Control Measure #5 of the MS4 permit.
In 2014, the Middle St. Croix Watershed Management Organization used a Clean Water grant to help nine
communities in the St. Croix Basin to adopt ordinance and code revisions that
incorporate MIDS stormwater standards. As of December 2016, eight of them — Bayport, Baytown Township, Lakeland Shores,
Lakeland, Lake St. Croix Beach, Oak Park Heights, St. Mary's Point, and West
Lakeland Township — have adopted the ordinances.
If your community is interested in adopting the MIDS
Community Assistance Package, or has adopted MIDS and you are not listed on this
page in the Stormwater Manual, please contact Anne Gelbmann.
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The Minimal Impact Design Standards (MIDS) calculator is a
widely used tool for stormwater management in Minnesota. It assists with permit
compliance, BMP design, calculation of volume or pollutant reductions, and more.
The MIDS calculator is a relatively simple tool not intended
to replace more sophisticated modeling. However, it provides technically
defensible information with fairly simple input requirements. Because the tool
is relatively simple, we continue to look for ways to improve the applicability
and accuracy of the tool.
In 2016, the MPCA contracted with an engineering firm to
provide numerous updates to the calculator, scheduled to be available in
mid-January. The
modified calculator, Version 3.0, is now available in the Minnesota
Stormwater Manual. Significant updates include:
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New BMPs
— On the opening screen, users are asked
if they are using the calculator for Construction Stormwater permit compliance.
If they answer “No”, a new BMP called “Stormwater disconnection (impervious
disconnection)” becomes available. This BMP allows users to route runoff from
impervious surfaces to pervious areas, where some of the water will infiltrate.
The BMP is not allowed for permit compliance because it does not constitute an
instantaneous volume reduction, as required in the permit. For more
information, see guidance
in the manual.
A new BMP was also added for underground
infiltration systems.
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Altered
volume credit — A BMP with a raised underdrain previously only received
volume credit for water stored below the underdrain. The calculator now allows
that volume plus infiltrating water, calculated as 0.06 inches per hour (D
soil) multiplied by the drawdown time.
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Reduced
infiltration rate — For permeable pavement with compacted subsoil, the
infiltration rate was reduced from 0.06 inches per hour to 0.03 inches per
hour.
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Iron-enhanced
sand filter option — An iron-enhanced option is available for sand filters.
If a user indicates they have included an amendment to reduce dissolved
phosphorus, they receive a 40 percent credit for dissolved phosphorus.
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Updated
harvest and reuse BMP — The harvest and use/reuse BMP underwent significant
updates
— The calculator now calculates daily potential
evapotranspiration (PET). A user can also enter a daily maximum rate of use.
The calculator uses the smaller of these two values to calculate the volume
credit.
— Users can enter a weekly volume used for
non-irrigation purposes. This volume is credited toward the performance goal. For A soils, the user can specify a weekly application rate of up to two
inches per week.
— If precipitation on a given day is less than the
daily use (for irrigation and non-irrigation), the difference between daily use
and precipitation is credited, if water is available in storage.
— For more information, see
the manual.
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Version 2
uploads — Version 2 files can be uploaded into the new version (Version 3).
The user will be required to update the Version 2 file to a Version 3 file.
Several minor changes were also made to the calculator. All
changes to the calculator will be discussed in a webinar, currently planned for
mid-March.
The MPCA has been developing guidance for stormwater and
rainwater harvest and use/reuse systems (with funds from the Clean Water Land
and Legacy Amendment):
Stormwater Manual updates:
In 2015, the MPCA contracted with an engineering firm to update the harvest and
use guidance in the Minnesota Stormwater Manual, with the help of a technical
advisory team. Now incorporated into the manual, the guidance
on includes design criteria, construction specifications, operation and
maintenance, water quality considerations, environmental concerns, cost benefit
considerations, case studies, calculating credits, definitions and more. We are
looking for case studies for the Stormwater Manual. If you have stormwater or rainwater reuse
projects that you would like to highlight, please contact Anne Gelbmann.
Interagency Water
Reuse team: With funding from the Clean Water Fund, an interagency team was
formed to develop best practices and policies recommendations — both regulatory
and non-regulatory — for water reuse. The team seeks input from a Stakeholder
Advisory Group on its recommendations. The next stakeholder meetings are
scheduled for February and April 2017. For more information, go to the water reuse web site.
 The City St. Anthony Village's water reuse facility collects stormwater runoff from Hennepin County Road 136, city hall, local streets, and backwash water from the city’s water treatment plant in a half million-gallon reservoir located underground. Water stored in the reservoir is recycled to irrigate a 20-acre site that includes a municipal park and St. Anthony’s City Hall campus.
Managing the amount of stormwater runoff from new impervious
surfaces is critical to protecting nearby waters from pollutants and recharging
groundwater. Designed infiltration is generally preferred by regulatory
agencies and stormwater practitioners and is the most commonly used technique
for reducing stormwater volume.
However, designed infiltration
is a bad idea in situations where there is heightened risk to groundwater.
Minnesota’s general stormwater permit for MS4s requires that every municipality
prohibit, without exception, the use
of designed infiltration of stormwater runoff under the following conditions:
- When the infiltration device will receive
stormwater runoff from one of these entities regulated under NPDES for
industrial stormwater: automobile salvage yards; scrap recycling and waste
recycling facilities; hazardous waste treatment, storage, or disposal
facilities; or air transportation facilities that conduct deicing activities
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When the infiltration device will receive
stormwater runoff from vehicle fueling (e.g., gas stations) and maintenance areas
- When the infiltration device will have less than
three feet of separation between the bottom of the device and groundwater or
the top of bedrock
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Where high levels of contaminants in soil or
groundwater will be mobilized by the infiltrating stormwater. Note: If stormwater infiltration is
proposed in areas with contamination, please conduct a screening
assessment using the guidelines found in the Minnesota
Stormwater Manual.
For more information on the general topic of stormwater infiltration,
please see the Minnesota Stormwater Manual.
Stormwater runoff from construction sites is a major
contributor to surface water pollution, according the U.S. EPA. Construction activity in Minnesota that will
disturb more than one acre must have an NPDES stormwater permit for
construction.
The Construction General Permit is typically re-issued every
five years. Although the current permit is scheduled to expire in August of
2018, the MPCA anticipates re-issuing the permit in fall 2017. With this early
issuance, the MPCA can put various NPDES permits in a cycle that better serves
permittees. The new permit will feature minor permit requirement revisions,
clarifications, and streamlined language that eliminates redundancies. The
permit will also be re-formatted to fit MPCA’s new data management system.
The MPCA will post the draft permit for public comment in
summer 2017, and invites all to participate. We’ll post updates on the construction
stormwater web page.
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The industrial stormwater permit requires
annual staff training for those carrying out the requirements of the industrial
stormwater permit. Internal staff can
train themselves, hire a consultant, or choose to attend a U of M workshop to
satisfy their training requirements. Be
sure to read the section in the industrial stormwater permit to ensure you’re
meeting all of the training requirements.
U
of M industrial stormwater training workshops now open:
Tuesday, Jan. 31, 2017, Verizon Wireless Center, Mankato
- Part of the MECA pre-conference events, this
half-day session will address SWPPP modifications due to benchmark monitoring
test result exceedances.
- MECA members can register at http://mnerosion.org/
Tuesday, March 7, 2017, MNDOT Training Facility, Arden Hills
Wednesday, May 10, 2017, MNDOT Training Facility, Arden Hills
We
know it rains in the winter and brief warm temperatures produce snow melt
conditions. But winter stormwater runoff takes salt and sand with it. Salt and
sand help keep people and drivers safe, but must be used
appropriately. Prevent ice build-up and keep up with shoveling and
snow-blowing to save time, money, and help the environment. Check out the
Mississippi Water Management Organization’s excellent article on winter
stormwater management: “How to Fight
Snow and Ice Without Polluting”
Want
to take winter stormwater management to the next step? Check out the MPCA’s Winter
Parking Lot and Sidewalk Maintenance Manual for tips and suggestions for
smart winter maintenance.
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Are you looking for ways to fund your stormwater projects? Minnesota
has funds available for stormwater projects from several sources: Clean Water
Land and Legacy Amendment, Clean Water Partnership, Federal 319, Point Source
Implementation Grants, State Revolving Fund, and grants and loans from the Metropolitan
Council, watershed districts, and soil and water conservation districts. Sources
of funding and recently funded projects are listed in the Minnesota
Stormwater Manual
The Board of Soil and Water Resources recently approved several
stormwater projects funded with the Clean Water Land and Legacy Amendment, including:
- Forest Lake High School stormwater reuse project
- Perro Creek urban stormwater quality
improvements
- Shields Lake stormwater harvest and irrigation
reuse system and alum treatment
- Iron enhanced sand filter basin at the Golden
Lake stormwater treatment pond
- Lakeville stormwater hydrodynamic separator
retrofit
- Alimagnet Lake stormwater improvement projects
- Six Mile Creek-East Auburn stormwater
enhancement project
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Oasis pond iron enhanced sand filter project
Recipients of the Metropolitan Council’s Livable Communities
grants (with many stormwater projects among them) are listed on the council’s
web site.
Learn about available funding for stormwater projects at two
upcoming presentations
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Wednesday, Jan. 25, 2017, Earl Brown Center, Brooklyn Park — MPCA’s Bill Dunn, Becky Sabie from the Public Facilities Authority, and
Brad Wozney from the Board of Water and Soil Resources will present at
the City Engineers Association of Minnesota.
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Monday, Feb. 6, 2017, MPCA headquarters, St. Paul — At the third annual Stormwater
Funding Strategies Workshop, from 1:00-4:30 p.m. on Feb. 6, staff from the
Board of Water and Soil Resources, Public Facilities Authority, Metropolitan
Council and the MPCA will discuss sources of funding for stormwater projects. Past
recipients of the funding sources will be there to discuss their experiences of
the process. The workshop will also be available online via WebEx — details
will be posted on the Funding page in the Stormwater
Manual
If you have questions about or suggestions for this newsletter, contact Anne Gelbmann, MPCA-St. Paul, 651-757-2384
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