Group_1 Stormwater Ponds Managing for
Sustainable
Stormwater Ponds
ESPM 4041W Problem Solving for Environmental Change
Report 1/7 Prepared for:
The City of Golden Valley
Prepared by:
Katherine Summers—Project leader
Aida Abebe—Team liaison
Darryl Gustad
James Perryman
December 10, 2012
Table of Contents
List of Figures...........................................................................................ii
List of Tables............................................................................................ii
Acknowledgments....................................................................................iii
Executive Summary.................................................................................iv
Introduction................................................................................................1
Vision Statement..................................................................................3
Goals and Objectives...........................................................................3
Methods.....................................................................................................4
Site Description....................................................................................4
Research Techniques...........................................................................4
Observations........................................................................................4
Interviews.............................................................................................4
Secondary Sources...............................................................................6
Geographic Information Systems (GIS)..............................................6
Findings and Recommendations................................................................6
Finding 1: Pond Construction..............................................................6
Recommendation 1..............................................................................7
Finding 2: Polycyclic Aromatic Hydrocarbons...................................8
Recommendation 2..............................................................................9
Finding 3: Limited Water Quality Data...............................................9
Recommendation 3a.............................................................................9
Recommendation 3b..........................................................................11
Finding 4: Infill of Stormwater Ponds by Pollutants.........................11
Recommendation 4............................................................................11
Conclusion...............................................................................................14
References................................................................................................14
Appendix A: Federal Emergency Management Agency Floodplain Map, Golden
Valley, Minnesota.
Appendix B: Impervious Surfaces Organized by Type, Golden Valley, Minnesota.
Appendix C: Pond Slope Record Sheet.
Appendix D: Sub-Watersheds Land Use Percentages where Constructed Ponds are
located, Golden Valley, Minnesota.
Appendix E: Sub-Watersheds Land Use Percentages where Natural Ponds are
located, Golden Valley, Minnesota.
Appendix F: Nutrient Levels in Natural Stormwater Ponds, Golden Valley,
Minnesota.
i
List of Figures
Figure 1: City boundaries with water bodies & major roads,
Golden Valley, Minnesota...................................................................2
Figure 2: Analyzed stormwater pond location map,
Golden Valley, Minnesota...................................................................5
Figure 3: Drawing of riparian zone............................................................7
List of Tables
Table 1: Sediment pickup performance by street sweeper model...........12
Table 2: Proposed street sweeping frequencies.......................................13
Table 3: Street sweeper cost data table....................................................14
ii
Acknowledgments
The success of this project has been dependent on many people. First and foremost,
we would like to thank Eric Eckman, Public Works Specialist for the City of Golden
Valley, for enthusiastically fielding countless emails and relaying information vital to
the success of this project. We would like to thank Kristen Nelson, Gary Johnson, and
Nick Bancks for their vision and support throughout this process, without which we
would have never been able to assist the City of Golden Valley.
We would also like to extend a sincere thank you to the following people for sharing
their knowledge, time, and energy: from Golden Valley, Utilities Supervisor Dave
Lemke and GIS Technician Heather Hegi; from the University of Minnesota,
Associate Professor of Forest Resources Tony D’Amato and and Associate Professor
of Forest Ecology Rebecca Montgomery.
iii
Executive Summary
Stormwater ponds, which filter pollutants from surface water runoff, make up a vital
part of the City of Golden Valley’s stormwater management system. Currently,
Golden Valley does not know whether these ponds are functioning sustainably. The
city engaged Environmental Sciences, Policy, and Management students from the
University of Minnesota to evaluate the conditions of these stormwater ponds and to
make recommendations to improve their sustainability.
Information we collected from personal interviews, journal articles and observations
suggested that stormwater ponds in Golden Valley face significant challenges with
pollution and sedimentation. In some cases, these ponds are prone to a particular
contaminant known as Polycyclic Aromatic Hydrocarbons, and in others there is
limited water quality data available for them. Our recommendations were designed to
address these main issues. The suggested recommendations are the following:
1.Evaluate riparian zones slope and slope of stormwater ponds.
2.Encourage compliance with Golden Valley’s ordinance prohibiting the use of
coal-tar based sealcoats for residential and commercial purposes.
3a. Consider establishing a rapid bioassessment program for ponds.
3b. Establish internships to support water quality data collection.
4. Evaluate an increase in street sweeping as a proactive strategy for water
quality protection.
iv
Introduction
Stormwater management is a vital part of Golden Valley’s natural resource
management. Bassett Creek, located within the city, is nationally recognized as a
floodplain (Appendix A) and makes the city vulnerable to flooding during periods of
intense rain (USDA, 2012). Thus, the city has implemented various stormwater
management strategies to protect its residents and prevent damage from storms. One
of these strategies is the construction of stormwater ponds, which store and filter
stormwater (University of Wisconsin Extension, 2012). The filtering capabilities of
these ponds is growing in importance; as nonpoint source pollution increases with
expanding urban development, the quality of water filtering out of stormwater ponds
can decrease, resulting in ponds that are nonfunctional and unsustainable over the
long-term. The use of stormwater ponds has been in effect in Golden Valley for many
years, but a thorough and consistent evaluation of their effectiveness has not been
done for all stormwater ponds. The goal of this report is to provide recommendations
that will improve stormwater pond functionality and, more broadly, sustainability.
Based on this assessment, this report makes recommendations that support
monitoring and management of stormwater ponds within the city in an effort to
improve the water quality of the associated watersheds in the Metropolitan Area
(hereafter referred to as the Twin Cities).
Golden Valley is located within the Twin Cities, west of downtown Minneapolis
(Figure 1), and has a population of approximately 20,000 residents (City of Golden
Valley, 2012). Close to half of the city is residential, with institutional and
recreational areas constituting another quarter of its area. Water bodies comprise
around 3% of the city’s total area and stormwater ponds comprise a small fraction of
this area (City of Golden Valley, 2012). However, stormwater ponds still have a
significant impact on how the city manages its stormwater. Golden Valley’s
stormwater ponds are both constructed and naturally occurring water bodies, with
constructed ponds mimicking the ecological function of a natural stormwater pond.
Both types of ponds have potential problems with sedimentation and other water
quality issues, which can decrease their utility as stormwater storage sites.
Golden Valley is a community that values the vitality and sustainability of its natural
resources (Envision Golden Valley, 2004). The management of these natural
resources has often been a difficult and sometimes debated undertaking for the city as
it works to balance the interests of community members with the financial and
practical restrictions of implementing natural resource management practices. This
tension is apparent in Golden Valley’s management of its stormwater ponds, which
provide several ecosystem services such as the storage of stormwater, water filtration,
and aesthetic benefits, but currently are not being sustainably managed using a
comprehensive natural resource management plan. The responsibility of managing
stormwater ponds often rests with the homeowners or the businesses whose
1
Figure 1: City Boundaries with Water Bodies & Major Roads, Golden Valley, Minnesota.
Designed By: Aida Abebe
Source: Data from Golden Valley & Northstar Mapper.
properties abut or contain stormwater ponds (Eckman, Pers. Comm., 2012). Since
many of these ponds are located on or near private properties, management
agreements between landowners and the City of Golden Valley are used to give
landowners the responsibility of monitoring stormwater ponds. Currently, many
stormwater ponds (both on public land and private land) are not being extensively
managed. The reasons for a lack of management can vary from property owners’
limited understanding of how stormwater ponds function, to a lack of access to
information or financial resources to assist with the management of stormwater
ponds. With this in mind, it was important to identify stormwater pond management
recommendations appropriate for private property owners, as well as the city’s
management of public ponds. The aim of this report is to create effective stormwater
pond monitoring and management recommendations so that the ponds and the
services they provide are sustainable over the long-term.
2
Vision Statement
As a city that values community involvement, Golden Valley began the Envision
Golden Valley initiative in 2004, which is still active today. Envision Golden Valley
is a consultative process that allows residents of Golden Valley to express their hopes
for the future of Golden Valley. The initiative resulted in a community vision that
incorporates two core values: connecting the people and places of Golden Valley, and
inspiring the continued care of Golden Valley. The vision expressed in Envision
Golden Valley also led us to prioritize the involvement of Golden Valley residents,
along with the opinions of knowledgeable professionals, in the recommendations
presented in this report.
As a class, we support the vision of Golden Valley with the following vision
statement, which links all seven reports in this series:
Our vision is to create a proactive, cohesive, and flexible natural resource
plan that supports community engagement and advances the role of Golden
Valley as a leader in natural resource management.
Guided by Golden Valley’s vision for its own future and our vision statement, we
believe our role is to be an advocate for Golden Valley efforts to shape a sustainable
future for itself. To fulfill this role, we recommend management strategies that
address stormwater before it reaches the ponds and monitoring strategies that allows
Golden Valley to stay informed on the conditions of the ponds.
Goals and Objectives
The goal of this report is to support the sustainable management of stormwater ponds
in Golden Valley. To accomplish this, we developed management recommendations
that are feasible given the budgetary and labor constraints the city of Golden Valley
faces. We hope to limit the costs associated with managing stormwater ponds by
focusing on stormwater before it drains into the ponds.
To achieve these goals, the following objectives guided our work:
1.Review relevant information concerning stormwater ponds,
2.Compile data of stormwater pond physical and biological characteristics,
3.Develop criteria for assessing the health, functionality, and sustainability of
the stormwater ponds,
4.Design monitoring strategies to accurately assess the condition of the
stormwater ponds overtime, and
5,Propose recommendations for improvement of current stormwater pond
management strategies,
3
Methods
Site Description
Golden Valley is a first-ring suburb in the Twin Cities metropolitan area, located just
west of the City of Minneapolis (Figure 1). The City of Golden Valley covers 10.5
square miles and has a very diverse land cover that is divided between residential
neighborhoods, commercial development, and recreational facilities (City of Golden
Valley, 2012). Four watersheds, Bassett Creek, Medicine Lake, Minnehaha Creek,
and Sweeney Lake, flow through Golden Valley, putting the city in a unique position
and making collaboration among the different municipalities concerning water
resources extremely important.
Research Techniques
For the scope of this project, both constructed stormwater ponds and natural
stormwater ponds were assessed (Figure 2). In an effort to adequately assess the
sustainability of these ponds, our team used a number of techniques, including
observations and interviews, along with primary and secondary data sources. These
techniques provide findings and evidence that was used to make informed
recommendations for sustainable stormwater pond management.
Observations
Observational data was gathered during a field visit to Golden Valley on September
8, 2012. We visited a random selection of Golden Valley’s stormwater ponds to gain
a general sense of pond surroundings and conditions. Observations were made by
walking the perimeter of the ponds and noting the level of vegetation present within
the water and the clarity of the water. Photos were taken to be used as references later
on in the project.
Interviews
Several interviews were conducted to provide qualitative data concerning innovative
stormwater pond management techniques, residential perceptions of stormwater
ponds, Golden Valley’s expectations for their stormwater ponds, and possible criteria
to use when assessing stormwater ponds. The interviewees included Dr. Tony
D’Amato (October 4, 2012), University of Minnesota silviculture professor, and Dr.
Rebecca Montgomery (September 14, 2012), University of Minnesota ecology
expert. In addition we spoke with Eric Eckman, Public Works Specialist for Golden
Valley, and Dave Lemke, Golden Valley Utilities Supervisor, on September 13, 2012,
who gave guidance on the fiscal, social, and political constraints of past and current
stormwater management activities in Golden Valley. Jeff Oliver, Golden Valley
4
engineer, and Public Works director Jeannine Clancy were interviewed on October 9,
2012 and provided information regarding potential criteria for assessing the
sustainability of ponds.
Figure 2: Analyzed stormwater pond location map, Golden Valley, Minnesota.
*Numbers indicate pond locations.
Designed by: Aida Abebe
Source: Data from Golden Valley & Northstar Mapper.
5
Secondary Sources
In addition to interviews and fieldwork, information was drawn from numerous
reports, journals articles, and books. These sources contributed facts about basic
stormwater pond functions, best management practices, and factors that influence
stormwater pond functionality. We relied heavily on the Golden Valley
Comprehensive Plan (2008) for guidance about current management and feasible
future management of the stormwater ponds. To determine the types of soils present
in Golden Valley, we retrieved information from Web Soil Survey (USDA, 2012).
Data was gathered concerning nutrient levels, sediment levels, and ecological
assessment factors for constructed stormwater ponds from the Golden Valley Surface
Water Management Plan (1999) and the waterpoly shapefile from the City of Golden
Valley.
Geographic Information Systems (GIS)
Two maps were created using the GIS program ArcMap. Components of the maps, or
layers in ArcMap language, were obtained from the City of Golden Valley and the
online resource NorthStar Mapper. These layers were combined in ArcMap to
produce two maps (Figure 1 & Figure 2). The layers shown in these two maps are
Golden Valley streets, major roads, water bodies, and city boundaries. Both maps
contain these four features, but with different emphases. The first map emphasized
the general features of Golden Valley that are relevant to the project, and the second
map showed the locations of the city’s numerous stormwater ponds.
Findings and Recommendations
Research, interviews, and fieldwork resulted in the following findings and
recommendations. As stated in the goals and objectives section of the introduction,
this report’s recommendations have been crafted to work within the fiscal and
practical constraints of Golden Valley.
Finding 1: Pond Construction
A fundamental aspect of a sustainable stormwater pond is proper construction. Slope
and vegetation buffers are two important components to a healthy, sustainably
functioning pond. During an initial visit to Golden Valley, we noticed some ponds
had a significant amount of erosion, causing turbidity and adding sediment directly
into the water from the sides of the pond. Standards used in some places (such as
Portland, Oregon) suggest that pond slope should not exceed a ratio of “3 horizontal
to 1 vertical,” keeping slope and depth as mild as possible (Portland Stormwater
6
Management Manual, 2008). For example, three communities—Portland, Oregon;
Louisville, Kentucky; and Fairfax County, Virginia—have all implemented
stormwater pond management that cites a 1:3 ratio for the slope of stormwater pond
edges (Jones, Guo, Urbonas, & Pittinger, 2006). Given that the majority of Golden
Valley’s stormwater ponds retain water continuously throughout the year, as opposed
to drying up between rain events like a detention pond would, vegetation plays a
large role in the filtration of sediment and nutrients from stormwater water
(Sustainable Drainage System for Stormwater Management, 2008). To reduce the
effects of erosion from flowing water, Portland, Oregon, intentionally designs
stormwater ponds to have a thick riparian zone of vegetation that will slow
stormwater flow into the pond, while also allowing large sediment particles to be
trapped by hearty vegetation and filter out before reaching the pond (Figure 3). These
stormwater ponds have an emergent plant zone (riparian zone) that is approximately
25% of the size of total pond surface area to adequately filter sediment and nutrients
from stormwater. This focus on pond construction exemplifies how many cities and
municipalities around the United States have implemented stormwater pond
construction and management techniques that set their Public Works departments up
for proactive management of sustainable stormwater ponds, by allowing departments
to anticipate function failures and establish practices that support successful, low
maintenance stormwater ponds.
Figure 3: Drawing of riparian zone.
Source: Clemson Cooperative Extension. 2012. Stormwater Pond Design, Construction, and Sedimentation.
Accessed 10 Nov. 2012 from: http://www.clemson.edu/extension/natural_resources/water/stormwater_ponds/
construct_repair_dredge/index.html
Recommendation 1: Evaluate riparian zones slope and slope of
stormwater ponds.
During the construction of new ponds and maintenance of pre-existing ponds,
consider slope reconstruction and/or refurbishing riparian zones as maintenance tasks
that can support the sustainability of stormwater ponds over the long-term. When
implementing riparian zones, their size should reflect the amount and proximity of
7
impervious surface surrounding the pond (Appendix B) because impervious surfaces
contribute to higher levels of runoff which contribute to sedimentation of stormwater
ponds. While riparian zones should be 25% of the size of the total pond area, large
areas of impervious surfaces surrounding a pond would call for a wider riparian zone.
Vegetation planted in riparian zones can include native wildflowers (such as the
Sharp-Lobed Hepatica, American Pasqueflower, and Marsh Marigold), forbs (such as
Burdick’s Leek and Putty-root), and native grasses that don’t require mowing (such
as Pennsylvania Sedge and Lady Fern). A full list of species that can be used in a
riparian zone can be found in Report #2/7 in this series, Assessment of Golden
Valley’s Vegetation Management Plan on Natural and Constructed Stormwater
Ponds.
Slope reconstruction can be achieved mechanically by dredging out the pond and
shaping pond sides to have a 1:3 slope. Pond slope can be measured from the high
water mark, used to determine maximum capacity. Slope is presented as a ratio, such
as 1:3, or a percentage such as 33%. Slope should be measured at several points
around the perimeter of a pond every year. Then this data can be analyzed for
changes over time (Appendix C). Given the fiscal implications of dredging, this
option can be coordinated with dredging operations already occurring. For ease of
implementation, we recommend that slope measurements be taken following the
biannual inspections of city subdivisions already set forth for storm sewer inspections
within Golden Valley. Stormwater ponds that have low rates of sedimentation are
able to produce higher quality of discharged water and need less maintenance (such
as dredging) than ponds with high levels of sedimentation. Implementing
management techniques that keep sediment from reaching a stormwater pond is a
proactive way to maintain the pond’s ability to sustainably function over the long-
term and decrease management costs associated with stormwater ponds.
Finding 2: Polycyclic Aromatic Hydrocarbons
Polycyclic Aromatic Hydrocarbons (PAHs) are coal-tar based contaminants that
increase the cost of removing sediment from Golden Valley stormwater ponds. Some
stormwater ponds in Golden Valley are known to be contaminated with PAHs. If not
managed or treated, PAHs raise potential risks for fish, wildlife, and humans (Crane,
2010). The largest contributor of these pollutants is sealcoats that are used in
residential driveways to produce the black coloration driveways are known for
(Crane, 2010). The majority of stormwater ponds in Golden Valley are surrounded by
residential and commercial developments (Appendix D & Appendix E) and most
stormwater ponds are in direct proximity to a residential driveway or commercial
parking lot. Sediment containing PAHs is a known hazardous waste, therefore
sediment contaminated by PAHs must be disposed of using expensive practices.
Minnesota law prohibits the use of products which contain PAHs for use by
municipalities on public impervious surfaces such as parking lots and driveways
(Crane, 2010).
8
Recommendation 2: Encourage compliance with Golden Valley’s
ordinance prohibiting the use of coal-tar based sealcoats for residential
and commercial purposes.
Due to the problems associated with PAHs in the sediment of stormwater ponds,
Golden Valley’s ordinance prohibiting the use of PAHs on private property is a long-
term solution that gradually reduces the presence of PAHs in the city’s stormwater
ponds. This ordinance prohibiting private use creates a uniform rule across land use
types. This ordinance synchronizes the public and private sectors and over time
alleviates the costs associated with removing sediment contaminated by PAHs. While
this ordinance may be met with concerns and resistance from Golden Valley
residents, education and public dialogue can be used to inform citizens of effective
alternatives of coal-tar sealcoats, such as asphalt based sealcoats which have 1,000
times less PAHs concentration (Crane, 2010). As Golden Valley considers this option
of educating the residents, it is useful to observe what other cities have done to
confront the PAHs problem. Twenty-five cities have ordinance that prohibits the use
of undiluted coal-tar based sealants on driveways, parking lots, or other surfaces.
Golden Valley can partner with these other cities to develop an education plan that
best fits Golden Valley’s goals. The ordinance which prohibits the use of PAHs by
residents could reduce costs of removing sediment, increase water quality, and
increase the overall health of the water bodies within the City of Golden Valley.
Therefore, educating residents about why this ordinance is important can move
Golden Valley toward PAH-free ponds.
Finding 3: Limited Water Quality Data
A vital aspect of effective stormwater pond management is having accurate water
quality data for stormwater ponds. However, Golden Valley lacks this information for
many of its ponds, especially natural ponds. Nutrient levels such as those of
phosphorus were missing for many of the natural ponds (Appendix F). This data is
crucial for the successful management of stormwater ponds because it reflects the
overall effectiveness and sustainability of stormwater ponds. The lack of this data
means that Golden Valley has limited knowledge concerning the current state of their
stormwater ponds.
Recommendation 3a: Consider establishing a rapid bioassessment
program for ponds
Rapid bioassessment is a strategy used by many local watershed districts in the
Midwest to monitor water quality (Lenat & Barbour, 1994). Usually used in rivers
and streams, these techniques can have practical applications for stormwater ponds
(Tixier et al., 2011). Rapid bioassessment techniques can be used to obtain reliable
water quality results in less time than traditional water quality measurement
techniques, such as the vertical Secchi disk and some chemical assessment techniques
9
(Lenat & Barbour, 1994; Steel & Neuhauser, 2002). Rapid bioassessment techniques
usually consist of sampling target organisms at a specific site within a pond. The
number and types of target organisms sampled indicates the overall quality of the
stormwater pond. Aside from aquatic organismal information, physical characteristics
that represent habitat quality of ponds, such as surrounding vegetation, are noted.
This helps link habitat factors to biological information. A reference site, usually a
minimally disturbed water body, is established as a baseline (Environmental
Protection Agency, 1999). The last step in rapid bioassessment is to combine results
from the above steps using an index such as the Pond Biodiversity Index
(Indermuehle et al., 2010). Indices assign scores indicative of different levels of pond
health (Southern California Coastal Water Research Project, 2011). These
assessments can be used to follow pond specific trends, average trends across Golden
Valley’s stormwater system, and inform sound management decisions.
A rapid bioassessment program would contribute to Golden Valley’s management of
stormwater ponds through the collection of accurate and universal water quality data
across all ponds which, as discussed earlier, does not exist for many of the natural
ponds in Golden Valley. The lack of data can be explained by the time, labor, and
financial constraints Public Works faces when it considers regular water quality
monitoring of ponds. Rapid bioassessment would be an important step in addressing
these constraints because it is cost-effective and requires less time relative to other
water quality assessment methods. Another advantage of using rapid bioassessment is
that the results can be presented in easily understandable formats (Sivaramakrishnan,
2000). Whereas traditional water quality methods incorporate the use of quantitative
analysis that requires specialized knowledge, rapid bioassessment assigns single
scores to results, which are easily interpretable by a wide audience that may be using
them to inform decisions. Another benefit is the accessibility of these results. Public
Works can share these easily understood results with its residents and other
municipalities in order to garner support for the program and receive feedback.
Designing an effective rapid bioassessment program for Golden Valley would mean
an initial investment in staff training about bioassessment techniques. In general, the
initial financial and planning investments needed for a working program can be seen
as balanced by the benefits it would provide over the long term. Monitoring pond
conditions using rapid bioassessment would allow Public Works to better assess the
efficiency and sustainability of stormwater ponds within the city, while not
overtaxing Public Works staff. With this strategy, Public Works would be proactively
managing its stormwater ponds. Over time, Golden Valley could see the
sustainability of ponds improve as the information gained from using rapid
bioassessment techniques is used to mitigate pollution and maintain quality water.
10
Recommendation 3b: Establish internships to support water quality data
collection
Given the limited time Public Works has to put towards on-site water quality
monitoring of stormwater ponds, establishing an unpaid internship would address a
critical barrier for the City of Golden Valley. One way to do this is to have student
interns run rapid bioassessments of the stormwater ponds. An internship program
would also have the added benefit of providing college students hands-on experience
in natural resource management. Internships can be semester-long or annual
depending on the needs of Golden Valley Public Works staff. A semester-long
internship could involve water quality measurements in stormwater ponds in
collaboration with the biannual inspections of city subdivisions already set forth for
storm sewer inspections within Golden Valley. This is the same time frame suggested
for vegetation monitoring in Report #2/7 of this series. Annual internships could
involve asking students to delve deeply into stormwater management by analyzing
data and preparing reports for relevant Public Works staff and city officials. The
work interns produce can be used to continually monitor stormwater pond conditions,
which is necessary for ensuring that they remain sustainable over the long-term.
Finding 4: Infill of Stormwater Ponds by Pollutants
Urban stormwater runoff can originate from houses, parks, buildings, streets, roads,
highways, parking lots and a host of other manmade structures (Appendix B). Runoff
can accumulate into significant amounts of pollutants that contribute to stormwater
pollutant runoff to surface waters. Pollutants, including sediment, debris, road salt,
and trace metals, all contribute to the ineffective functioning of a stormwater pond.
Recommendation 4: Evaluate an increase in street sweeping as a
proactive strategy for water quality protection
Street sweeping can minimize the impacts pollutants have on stormwater ponds. As
stated in a previous recommendation, dredging is an effective, but costly strategy to
remove organic matter from stormwater ponds. Therefore, reducing the amount of
sediment that accumulates in stormwater ponds is a proactive step to reducing the
cost of dredging operations over the years. Street sweeping to collect sediment can be
a cost effective way to reduce dredging costs, by reducing the number of dredging
operations. In particular, Street sweeping during certain times of the year is an
efficient way to reduce the loading of biomass and pollutants in stormwater ponds.
Urban runoff is a major problem in the City of Golden Valley and around the country.
The significant amount of pollutants that come from impervious surfaces like streets,
roads, and highways are major contributors to surface water runoff. Street sweeping
machines can make a huge impact on reducing the influx of pollutants to ponds,
wetlands, and impaired waters. Street sweeping can also improve the aesthetics of
11
Particle
size
group
Particle
size range
(microns
Street sweeping technologies
NURPM
mechanical
Newer
mechanical
Tandem
sweeping
Regenerative
air
Enviro-
Whirl
1<63 9.0 5.8 2.0 0.0 0.0
2-125 12.0 5.8 2.0 0.0 0.0
3-250 18.0 5.3 2.3 0.9 0.0
4-600 18.0 2.5 2.3 1.9 0.0
5-1000 12.0 0.4 0.8 0.7 0.0
6-2000 4.2 0.5 0.6 0.7 0.0
7-6370 3.6 0.3 0.5 0.0 0.0
8>6370 1.8 0.0 0.0 0.0 0.0
roadways, while reducing sand, sediment, and pollutants in catch basins, which will
reduce additional maintenance costs over time.
Although traditional sweepers generally keep streets aesthetically pleasing by
removing leaves, litter, and large-sized sediment, they do not pick up the fine road
dust and particles that carry pollutants to our waterways (contaminants are known to
concentrate in particles that are less than 0.63 micron) (US Environmental Protection
Agency, 1983). However, newer street sweeping technologies and increased
sweeping frequency are very effective at picking up fine particles that are highly
contaminated and thereby reducing the amount of pollutants of urban runoff
(Sutherland & Jelen, 1996). There are currently several types of street sweepers
available: mechanical, regenerative air, and vacuum filter. Each of these street
sweeping technologies differ in relation to different pollutant types (large debris to
particles less than 10 microns in diameter), surfaces, travel distances, noise
ordinances, and costs. Municipalities often find it useful to have a complement of
each type of street sweeper in their fleet (California Stormwater Quality Association,
2003). Evaluating the ability of street sweeping to reduce pollutant loads is dependent
on three things: (1) the innate ability of a street sweeper to remove accumulated
sediment, (2) the environmental dynamics of sediment accumulation and re-
suspension, and (3) the sediment runoff during storm events. Roger Sutherland,
arguably the world’s top expert on street sweeping, designed the Simplified
Particulate Transport Model (SIMPTM) that can simulate the interaction of
accumulation, runoff, and street sweeper pickup that occurs over time (Sutherland &
Jelen, 1993). This model has been used to compare five street sweeping technologies
to help determine the best technology to use for the different particle size reduction
(Table 1).
Table 1: Sediment pickup performance by street sweeper model.
Source: Pickup performance model and street sweeping frequency graph. Accessed 26 Oct. 2012 from:
http://pacificwr.com/Publications/Chapter9-Contrary_to_Conv_Wisdom.pdf
Coupled with sweeping technologies, the frequency of street sweeping is another
factor that is important in the reduction of pollutants to receiving waters. According
to the Minnesota Department of Transportation (MnDOT), the minimum and
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maximum frequencies for street sweeping can vary by land-use area (Table 2).
Comparatively, the curve of expected annual runoff reduction for varied frequencies
of street sweeping events by the five technologies finds maximum efficiency of
residential neighborhoods at weekly and biweekly sweepings. Based on the proposed
sweeping frequencies by MnDOT, increased frequency can greatly reduce pollutant
load in stormwater runoff. However, to be cost effective, sweeping frequency is
conditional and should be determined by the local content, such as road appearance,
air quality, roadway maintenance, safety, and water quality.
Table 2: Proposed street sweeping frequencies.
Area Minimum frequency Maximum frequency
Arterials 9 times per year 16 times per year
Commercial 9 times per year 16 times per year
Light Industrial 6 times per year 9 times per year
Heavy Industrial 9 times per year 16 times per year
Residential 4 times per year 9 times per year
Central Business District Biweekly 2 times per week
Source: Minnesota Department of Transportation. 2008. Resource for Implementing a Street Sweeping
Best Practice. Accessed 2 Nov. 2012 from: http://www.lrrb.org/media/reports/2008RIC06.pdf
It is clear from the pickup performance model that the most expensive
sweepers—tandem sweeping, regenerative, and Enviro-whirl—are the optimum
choices for removing diverse sizes of particles (Table 1), but price and personal
preference are important selection criteria for most users (Keating, 2012). The largest
expenditures for street sweeping programs are in staffing and equipment (CASQA,
2003). According to Resource for Implementing a Street Sweeping Best Practice
(Minnesota Department of Transportation, 2008), the cost of purchasing a street
sweeper can be quite high depending on a number of options and accessories (Table
3). Also, it is important to note in purchasing decisions that while the high efficiency
sweepers (e.g., regenerative-air and vacuum) are more expensive, their average
service life range is longer. An appropriate street sweeper and frequency sweeping
have significant benefits in achieving quality receiving water, improved road
appearance, and safety; they also improve air quality, which can improve the
wellbeing of Golden Valley residents, as there is a direct relationship between high
levels of fine particles in the surrounding air and health-related problems (Morgan,
2007).
Stormwater picks up nutrients, sediment, and chemical contaminants as it flows
across roads, yards, golf courses, parking lots, and construction sites. This polluted
runoff travels into storm drains and local waterways that eventually drain into
receiving waters reducing their sustainability. However, studies have shown that
utilizing street sweeping best practices can improve water quality as well as provide
other environmental benefits.
13
Table 3: Street sweeper cost data table.
Sweeper type Purchase price
Mechanical$140,000+
Regenerative-air/newer model$175,000 to $250,000
Source: Schilling, J.. 2005. Street Sweeping – Report No. 1, State of the Practice. Prepared for
Ramsey-Washington Metro Watershed District. Accessed 15 Nov. 2012 from:
http://www.rwmwd.org/vertical/Sites/%7BAB493DE7-F6CB-4A58-AFE0-
56D80D38CD24%7D/uploads/%7B9EE2CF53-44F6-4614-BE01-F80EE0C151E1%7D.PDF
Conclusion
The purpose of this project was to assess the sustainability of stormwater ponds in
Golden Valley, Minnesota, which are a vital part of its stormwater system. Based on
this assessment, recommendations were made that could improve the sustainability of
these ponds. Our assessment revealed that many stormwater ponds lacked the water
quality data needed to determine their sustainability and that they have problems with
pollution and sedimentation. These findings led to recommendations which would
increase the information available for determining the sustainability of stormwater
ponds, as well as improve their functionality by decreasing the amount of sediment
and pollutants flowing into them. These recommendations had to factor in the time,
labor and financial constraints the Golden Valley Public Works department faces
when it considers management practices for these ponds. The recommendations were
developed to save Public Works time and money, while also ensuring the
sustainability of stormwater ponds.
The results of this project show that the City of Golden Valley faces several
challenges in the management of its stormwater ponds, which can be overcome by
implementing time and money saving technologies as well as innovative management
strategies. This report, along with the other reports in this series, provides the City of
Golden Valley with many tools and strategies that can be used to manage natural
resources more sustainably. In total all the recommendations provide material for
establishing a natural resource management plan and a foundation to build a more
sustainable future.
References
California Stormwater Quality Association (CASQA). 2003. Best Management
Practices (BMP) Handbook, Municipal. Accessed 15 Nov. 2012 from:
http://www.cabmphandbooks.com/Documents/Municipal/SC-70.pdf.
Clemson Cooperative Extension. 2012. Stormwater Pond Design, Construction, and
Sedimentation. Accessed 10 Nov. 2012 from:
14
http://www.clemson.edu/extension/natural_resources/water/stormwater_ponds/co
nstruct_repair_dredge/index.html
Eckman, E. Personal Interview. Retrieved on 13 Sep. 2012.
Eckman, E., J. Clancy, A., Lundstrom, and J. Oliver. Personal Interview, 9 Oct. 2012.
Envision Golden Valley. 2004. A Shared Vision for Golden Valley's Future. Accessed
15 Sep. 2012 from:
http://www.goldenvalleymn.gov/envision/guide/PDF/EnvisionReport.pdf.
Environmental Protection Agency, Water Planning Division. 1983. Results of the
National Urban Runoff Program. Vol 1. Accessed 22 Nov. 2012 from:
http://nepis.epa.gov/Exe/ZyNET.exe/500025BS.TXT?ZyActionD=ZyDocument
&Client=EPA&Index=1981+Thru+1985&Docs=&Query=&Time=&EndTime=&
SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&
QFieldMonth=&QFieldDay=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&F
ile=D%3A%5Czyfiles%5CIndex%20Data%5C81thru85%5CTxt%5C00000014%
5C500025BS.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h
%7C-
&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y1
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kPage=x&ZyPURL
Environmental Protection Agency. 1999. Rapid Bioassessment Protocols for Use in
Streams and Wadeable Rivers: Periphyton, Benthic Macroinvertebrates, and Fish
- Second Edition. Accessed 12 Nov. 2012 from:
http://water.epa.gov/scitech/monitoring/rsl/bioassessment/index.cfm
City of Golden Valley. 2004. A Shared Vision for Golden Valley’s Future. Accessed
26 Sept. 2012 from: http://www.goldenvalleymn.gov/envision/guide/index.html
City of Golden Valley. 2008. Comprehensive Plan. Accessed 26 Sept. 2012 from:
http://www.goldenvalleymn.gov/planning/comprehensiveplan/index.php
City of Golden Valley. 2012. Demographics. Accessed 26 Sept. 2012 from:
http://www.goldenvalleymn.gov/about/demographics.php
City of Golden Valley. 2012. Land Use. Accessed 27 Sept. 2012 from:
http://www.goldenvalleymn.gov/about/landuse/index.php
Indermuehle, N., V. Rosset, S. Angelibert, and B. Oertil. 2010. The pond biodiversity
index "IBEM": a new tool for the rapid assessment of biodiversity in ponds from
Switzerland. Part 2. Method description and examples of application. Limnetica.
Accessed 20 Oct. 2012 from
http://www.sciencedirect.com.ezp1.lib.umn.edu/science/article/pii/S1470160X10
001421
Jones J., J. Guo, B. Urbonas, and R. Pittinger. 2006. Essential Safety Considerations
for Urban Stormwater Retention and Detention Ponds. Stormwater Magazine.
Accessed 19 Nov. 2012 from:
http://www.udfcd.org/resources/pdf/conferences/conf2006/5-
1%20Jones%20Safety%20Considerations.pdf
Keating, J. 2012. Street Sweeper, Picking up Speed and Quieting Down. Accessed 2
Nov. 2012 from: http://www.forester.net/s w_0207_street.html
15
Lenat, D., and M. Barbour. 1994. Biological Monitoring of Aquatic Systems.
Accessed 15 Oct. 2012 from:
http://books.google.com/books?hl=en&lr=&id=J1bbo7JS__8C&oi=fnd&pg=PA1
87&dq=cost+effective+water+quality+monitoring+strategy&ots=z72vcTOBkj&s
ig=EHG-
5eEU0cw24bkuddxPTCafI9Q#v=onepage&q=cost%20effective%20water%20qu
ality%20monitoring%20strategy&f=false
Morgan, C. 2007. In Clean Roads to Clean Air Program, City of Toronto, Ontario,
Canada. Accessed 5 Nov. 2012 from: http://www.toronto.ca/teo/pdf/cleanroads-
cleanair-sept07.pdf.
Minnesota Pollution Control Agency (MPCA). 2010. Crane, J.. Contamination of
Stormwater Pond Sediments by Polycyclic Aromatic Hydrocarbons in Minnesota.
Accessed 27 Oct. 2012 from:
http://www.leg.state.mn.us/docs/2010/other/100587.pdf
Minnesota Pollution Control Agency. 2000. Stormwater Pond Systems. Accessed 4
Nov. 2012 from: http://156.98.19.106/index.php/view-document.html?gid=7156
Neuhauser S., Steel, A. A Comparison of Methods for Measuring Water Quality.
Accessed 28 Oct. 2012 from: www.nrcse.washington.edu/pdf/trs23_clarity.pdf
Southern California Coastal Water Research Project. 2011. Project Group: Stream
Bioassessment Tool Development. Accessed 22 Oct. 2012 from:
http://www.sccwrp.org/ResearchAreas/Bioassessment/FreshwaterBioassessment/
StreamBioassessmentTools.aspx
Sivaramakrishnan, K. 2000. A Refined Rapid Bioassessment Protocol for Benthic
Macro-invertebrates for Use In Peninsular Indian Streams and Rivers. Accessed
22 Oct. 2012 from:
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Sutherland, R., Jelen, S. 1993. Simplified Particulate Transport Model-Users
Manual, Version 3.1. Accessed 7 Nov. 2012 from:
http://www.pacificwr.com/Publications/Newsletter_Vol4_No4.pdf
Sutherland, R., and S. Jelen. 1996. Sophisticated Stormwater Quality Monitoring is
Worth the Effort. Advances in Modeling the Management of Stormwater Impacts.
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Advances_in_Modeling.pdf
Tixier, G., Q. Rochfort, L. Grapentine, K. Marsalek, and M. Lafont. 2011. In search
effective bioassessment of urban stormwater pond sediments: enhancing the
'sediment quality triad' approach with oligochaete metrics. Water Science
Technology. Accessed 20 Oct. 2012 from:
http://www.ncbi.nlm.nih.gov/pubmed/2217964
US Department of Agriculture. 2012. Web soil survey. Accessed 15 Sep. 2012 from:
http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm
University of California, Division of Agriculture and Natural Resources. 2012. How
to Measure a Pond. Accessed 19 Nov. 2012 from:
http://manure.ucdavis.edu/http___ucanrorg_sites_ucmanure_Measuring_Liquid_
Manure_Nutrients_/Pond_Drop_Measurement_Method/Pond_Drop_Measuremen
t_Method/How_to_Measure_a_Pond/
16
University of Wisconsin Extension. Options for Open Space Stormwater Ponds.
University of Wisconsin Extension, Southeast Wisconsin Fox River Partnership
Team. Accessed 26 Sep. 2012 from:
http://basineducation.uwexedu/southeastfox/pdf/Open%20Space%20Files/stormw
aterponds.pdf
17
Appendix A: Federal Emergency Management Agency Floodplain Map, Golden Valley, Minnesota.
Source: Figure 1. FIRM, Hennepin County, Minnesota, Panel 194." Map. Fema.gov. Federal Emergency Management Agency, 2 Sept. 2004. Web. 16 Oct. 2012.
http://map1.msc.fema.gov/idms/IntraView.cgi?KEY=20385131&IFIT=1
Appendix B: Impervious Surfaces Organized by Type, Golden Valley, Minnesota.
Designed By: Aida Abebe
Source: Shapefile from Golden Valley, 2012
Appendix C: Pond Slope Record Sheet.
Step 1: Make mark on pond edge
Step 2: Measure horizontal distance
Step 3: Measure vertical distance
Pond Name:______________________
Pond Location:____________________
Date Location on Pond Perimeter Horizontal Vertical Slope Grade Notes
Appendix D: Sub-Watersheds Land Use Percentages where Constructed Ponds are located,
Golden Valley, Minnesota. .
Current
Land Use by
Sub
watershed (as
a %)
Constructed
Ponds
Water
Body ID#
Sub
watershed
Pond
Name
Area(Acres) Residential Multi-
residential
Commercial Open
1 BC-55 BC10-5 Untitled 31.7 10 85
2 BC-61 BC84-6 Golden
Medows
Pond
92.2 76 22
3 BC-65 BC83-3 Medicine
Lake Road
Pond
11.7 100
4 BC-74 BC9-3 25.3 61 39
5 BC-112 BC5-9 Dahlberg
Pond
26.7 100
6 BC-124 BC44-4 Wirth Pond 12.8 49 51
7 BC-136 BC102-6 Golden
Ridge Pond
77.2 34 66
8 BC-166 BC10-3 Untitled 120.9 2 98
9
10
11
ML-1b
ML-1c
ML-1d
ML2 115.6 83.9 8 9
12 SL-33 SL4-3 Untitled 14.9 97 3
13 SL-34 SL1-6 Toledo-
Angelo
Pond
20.5 100
14 SL-72 SL4-4 Untitled 8.6 86 14
15 SL-75 SL4-3 Untitled 14.9 97 3
16 SL-91 SL5-15 Untitled 32.7 81 10 9
17 - ML-2 Untitled - - - - -
Source: Barr Engineering. 2009. City of Golden Valley Surface Water Management Plan. Retrieved on 10 Oct. 2012
from:https://moodle2.umn.edu/mod/folder/view.php?id=729656
Appendix E: Sub-watersheds Land Use Percentages where Natural Ponds are located,
Golden Valley, Minnesota.
Source: Barr Engineering. 2009. City of Golden Valley Surface Water Management Plan. Retrieved on 10 Oct. 2012
from:https://moodle2.umn.edu/mod/folder/view.php?id=729656
Wetlands Water
Body ID#
Sub
watershed
Pond
Name
Area(Acres) Residential Multi-
residential
Commercial Open
1
BC-160 BC7-11 Untitled 11.7 100
2 SL-59
SL-62
SL21-2
Untitled 60 100
3
4 SL-63 SL21-5 Untitled 30.7 100
5 SL-65 SL21-4 Untitled 40.9 100
6 SL-66 SL21-3 Untitled 42 100
7
8
BC-132
BC-133
BC44-2
BC44-2
Untitled 68.3 100
9 MC-1 MC-3 Untitled - - - - -
10 SL-17 SL5-6 Untitled 48.4 53 34 13
11 SL-11 SL5-9 Untitled 14.2 100
12 SL-13 SL5-10 Untitled 30,9 100
13 SL-16 SL5-16 Untitled 13,5 100
14
15
16
17
16
19
BC-46
BC-47
BC-48
BC-49
BC-50
BC-156
BC11-11 Untitled -
-
-
-
-
20 BC-80 BC7-9 Untitled 13.5 70 30
21
22
23
24
25
BC-81
BC-82
BC-83
BC-84
BC-85
BC7-8 Untitled
11 51 49
Appendix F : Nutrient Levels in Natural Stormwater Ponds, Golden Valley, Minnesota.
Source: Barr Engineering. 2009. City of Golden Valley Surface Water Management Plan. Retrieved on 10 Oct. 2012.
From:https://moodle2.umn.edu/mod/folder/view.php?id=729656
Wetlands
and
Wetlands
Acting as
Ponds
Water Body
That Resides
in
Subwatershed
Sub
watershed
Area
(acres)
Total
Suspended
Solids
(lbs)
Suspended
Solids (lbs
per acre)
%
Above
or
Below
Average
SS
Total
Phosphorus
(lbs)
Phosphorus
lbs/per
Acre
% Above
or Below
Average
Phosphorus
2 1 BC-160 BC7-11 11.7 4,300 367.52 15 11 .94 6
2
3
SL-59
SL-62
SL21-2
SL21-2
60.1 17,700 294.51 -34 28 .47 -64
4 SL-63 SL21-5 30.7 7,800 254.07 -43 26 .85 -35
6 5 SL-65 SL21-4 40.9 13,000 317.85 -29 43 1.05 -19
6 SL-66 SL21-3 42.0 11,700 278.57 -37 38 .90 -30
34 7
8
BC-132
BC-133
BC44-2
68.3 20,900 306.00 -4 88 1.29 46
1 9 MC-1 MC-3 31.8 11,600 364.78 189 37 1.16 730
10 SL-17 SL5-6 48.4 14,100 291.32 -34 1 .02 -98
7 11 SL-11 SL5-9 14.2 4,400 309.86 -30 15 1.06 -19
12 SL-13 SL5-10 9,400 304.21 -32 32 33 1.07 -18
13 SL-16 SL5-16 13.5 3,300 244.44 -45 1 .07 -94
14
15
16
17
18
19
BC-46
BC-47
BC-48
BC-49
BC-50
BC-156
BC11-11 - - - - - - -
5 20 BC-80 BC7-9 13.5 4,000 296.30 -7 11 .81 -8
21
22
23
24
25
BC-81
BC-82
BC-83
BC-84
BC-85
BC7-8 11.0 3,200 290.91 -9 8 .73 -18