Watershed Achievements Report

Watershed Minnesota River Achievements Basin Report 2008
Watershed Achievements Report Statewide 2015
Lower Minnesota River Watershed
Quantifying Nutrient Removal by Street
Sweeping
Street sweeping has traditionally been regarding as
a “housekeeping” task in stormwater management,
with early studies indicating that sweeping had little
impact on reducing stormwater nutrients. This study
revisited the issue, and was unique in several aspects:
(1) we included streets with tree canopy covers (over the
streets) ranging from 0 to 20%; (2) measured nutrients
in the sweepings removed, including nutrients in
coarse organics (leaves, etc.), as well as fines; (3) swept
through the entire snow-free season, including autumn
leaf fall. Results show that the coarse organic fraction
of sweepings included 42% of the P and 75% of the
N in the sweepings. Nutrient removal increased with
increasing canopy percentages, and with increasing
sweeping frequency. During the spring and fall, the cost
per pound of P removed dropped below $100/lb, an
order of magnitude lower than for stormwater ponds. We
developed a spreadsheet planning calculator designed
to help public works and streets departments decide
whether enhanced sweeping would work for their cities,
supported by a User Support Manual, and convened
two translational workshops, training ~ 80 professionals
representing many of the municipalities in the Twin Cities
region.
Goals
• Plan and conduct the Prior Lake Street Sweeping
Experiment
• Analyze results and develop a street sweeping planning
tool for cities
• Conduct translational workshops, disseminate findings
in multiple venues
Results that count
• The project showed that enhanced street sweeping can
remove substantial amounts of nutrients, especially in
the form of coarse organics, and that the removal of
nutrients for a given route can be modeled from tree
canopy cover over streets and sweeping frequency
within each month of the year.
• We embedded the modeling approach into a street
sweeping planning calculator that enables public works
and streets departments to estimate removal of solids,
N, and P for each sweeping route, the cost, and the
cost/lb of pollutant removed. The Excel-based planning
calculator and User Support Manual are posted on a
website.
• Translation of research results to practice occurred
through several mechanisms: translational workshops,
publication of key findings in Stormwater Magazine
and a Stormwater Updates newsletter; and
presentation in numerous forums, including a Low
Impact Development Conference and a state-wide
water resources conference, at several public works
departments, watershed management districts, guest
lectures, and others.
Lessons learned
As to “lessons learned”, this has been one of the most
rapidly translated projects that either the Principal
Investigator (PI) or co-PI has worked on, and an
experience that we hope to repeat. This occurred for two
reasons: (1) our research filled a void in knowledge that,
once filled, had enormous practical application; and (2)
we developed an accessible modeling tool that is simple
enough to use that it is leading to rapid adoption by
cities.
With regard to MPCA, we greatly appreciated Greg
Johnson’s (our project manager) effort to enable us to
present our findings of two 319 projects to MPCA offices
statewide, and have suggested that MPCA might in
the future hold “319 workshops” for projects to share
findings.
Financial information
Funding type: Section 319
Grant amount: $285,754
In-kind: $150,045
Matching funds: $96,622
Contact information
Kevin McKoskey
University of Minnesota
450 McNamara Alumni Center
200 Oak Street
Minneapolis, MN 55455
612-624-5066
MPCA Project Manager: Greg Johnson
Minnesota Pollution Control Agency www.pca.state.mn.us 73