Concurrent Session V, Track A: Considerations for Implementing Green Stormwater Infrastructure
1063: Maintenance-Informed Green Infrastructure Design
Author(s): Ryan Fucci, HDR, Inc.
Description: Green infrastructure has been used for more than a decade in historic urban communities to reduce stormwater inflow to combined sewer systems.
To realize the full potential of these benefits, GSI needs to be implemented and managed successfully. Design is an important factor in this process, but successful GSI projects can’t start and end at the desktop. Proper construction and maintenance practices are paramount to the success of green infrastructure programs. Moreover, evaluating and documenting what maintenance techniques work and why creates a valuable feedback loop between GSI maintenance and GSI design practitioners, leading to maintenance-informed designs and more practical and sustainable GSI systems.
This presentation will focus on key design considerations accumulated over a decade of GSI design and maintenance program experience. Drawn from direct experience with comprehensive green infrastructure programs including Philadelphia, Washington DC, and New York City, each example presented will demonstrate how maintenance best practices, industry experience and lessons learned were incorporated into specific design elements. Examples will be relevant to our local design challenges whether they stem from regulatory drivers, climate, or differing urban characteristics.
Key GSI design considerations, adapted from lessons learned through maintenance, to be covered include:
- Creation of edge conditions that promote healthy plant growth, protect existing infrastructure, and extend the life of systems
- Incorporation of maintenance-friendly sedimentation areas into stormwater inlet locations and energy dissipation structures.
- Integration into multimodal urban landscapes and promotion of safe transit practices.
- Establishment of hearty low maintenance vegetation that is resilient to erosive flows, sedimentation, standing water, and salt.
1029: This Looks Different Because It Should: Community-Driven GI that Considers Environmental Equity in Minneapolis
Author(s): Allison Bell, City of Minneapolis; Bridget Osborn, HR Green
Description: Upon seeing a large set of transportation and parks coming up all located within the City of Minneapolis South Side Green Zone (SSGZ), the city wanted to leverage the opportunity to incorporate and optimize the green infrastructure (GI) in the area within these projects. Minneapolis Green Zones are communities that have been deeply affected by pollution, racism, and other factors, and the city is working in these communities to address environmental issues. The communities identified GI, tree canopy, and green jobs as major elements that would contribute to the work to improve the conditions they experience. The City partnered with HR Green to work with the SSGZ Council and community members along with the transportation design teams to understand priorities and opportunities to maximize the impacts these projects could have in the area. This effort focused on two of the upcoming projects ahead of a much larger study of the entire zone.
We learned to take a different approach, to navigate working with an over-burdened community in such a way that does not increase the burden and allows for effective input. Sometimes this meant acknowledging historic racism in the development of the roads in the area, and sometimes this meant translating how city and engineering priorities aligned with community feedback. The community and the city worked together to develop goals and priorities for GI in this area.
The project team made recommendations to incorporate GI within the road projects that aligned with the goals and priorities. They analyzed feasibility, impact, and costs, and laid out a plan for implementation and funding.
In this presentation, we will walk through how we learned to work with the community, how to best listen and incorporate needs, and how to communicate and inform community members. We will also discuss the GI optimization work and how we translated community-driven priorities and city water quality priorities into project recommendations.
1065: Constructing Linear GSI: What’s Working, What’s Not, and What Might Be
Author(s): Katie Kowalczyk, City of Minneapolis; Allison Bell, City of Minneapolis
Description: The City of Minneapolis started adding green stormwater infrastructure (GSI) to road projects in 2019. In the years since, the program has grown and the City passed an updated stormwater ordinance in 2022 that requires linear projects to include GSI. GSI is relatively new to the region, and it is very challenging to fit, properly install, and ensure long term success in linear projects in a fully developed urban area with challenging conditions including periods of extreme heat and drought and six months of winter. With so many GSI facilities being installed each year, there is plenty of opportunity to test out different designs to understand the best ways to get linear GSI to thrive.
So far, on linear GSI, mostly bioretention basins within the right-of-way, the city has trialed a variety of bioretention media, vegetation types, and inlets. Some examples of the elements we have tested include vegetation type, such as native sod and a combination of seeds, plugs, and pot, and plant species. We considered these in a variety of conditions, such as shade or whether or not the vegetation would expect to be inundated for any period of time. We have looked at overall vegetation heath and how well the initial vegetation establishes and thrives during challenging climate conditions. We have also designed and installed over 10 types of inlets into roadside bioretention areas. We are trying to determine the best design to convey flow into the facilities, taking into account a variety of conditions such as slope, location within the basin, drainage area, pollutant load expectation, and maintenance considerations. We have a list of success and recommendations, failures and lesson-learned, and we continue to test out designs in projects planned for the future.
In this presentation, we will walk through the various GSI elements we have tested out for our linear GSI projects. We will summarize what was successful, what failed, and what we are continuing to trial and examine.
1086: How to Be Everywhere at Once: The Development of a GSI Hybrid Construction and Inspection Guide for and with City Inspectors
Author(s): Allison Bell, City of Minneapolis; Katie Kowalczky, City of Minneapolis
Description: The City of Minneapolis started adding green stormwater infrastructure (GSI) to road projects in 2019. In the years since, the program has grown and the City passed an updated stormwater ordinance in 2022 that requires linear projects to include GSI. Now, the City installs 100’s of facilities every year, but there is still only one dedicated staff member, the GI Coordinator, to oversee the proper construction of all of the facilities throughout the city each construction season. To manage this, the inspectors and the GI program staff worked together to develop the best method to ensure proper construction on all facilities: a GSI hybrid construction and inspection guide.
The City inspectors responsible for the majority of the GSI built along a transportation project are primarily trained and experienced in standard transportation projects. GI is new to the region, from design to construction, so there is a fairly limited pool of expertise to get GI into the projects. As the GI program grew, we were able to first establish a GI preconstruction meeting that addressed some of the major issues we faced in the early construction days. An inspection checklist was then developed.
From there, the inspectors and the GI Coordinator determined that they needed more. They needed a guide that would both instruct inspectors through key inspection points, but also help them understand the purpose and function of GI elements so that they could ultimately support successful construction. The guide is laid out in the order that GSI construction happens on a typical road project. It includes details, example images, definitions, and explicit direction on when, how, and what to inspect.
In this presentation, we will walk through the construction oversight process, and how it evolved from a string of calls for help to a collaborative guidance and inspection document.
Concurrent Session V, Track B: River Habitat and Connectivity
1020: The Effects of Dams on Native Fish Communities
Author(s): Amy Childers, MN DNR; Luther Aadland, private consultant; Neil Haugerud, MN DNR; Dan O'Shea, MN DNR; Mark Ellefson, MN DNR
Description: Dams have a variety of detrimental effects on river health and aquatic communities. The effects of dams on fish migrations and the decline of migratory species have been acknowledged for over 300 years. How extensive is the effect of dams on Minnesota’s native fish communities? To address this question, the presence/absence of fish species in the upstream versus downstream watersheds of 33 dams throughout Minnesota was analyzed. The dams assessed are, or were, located in tributaries and mainstems of the Minnesota, Red River of the North, St. Croix, St. Louis, Missouri and Mississippi river watersheds. Georeferenced fish records from reliable sources were used to tabulate the presence and absence of fish above and below the barriers.
On average, species richness declined by 45% for complete barriers, 27% for near-complete barriers and 17% for barriers that are/were inundated at bankfull flows. Habitat generalists, tolerant, lake-oriented, headwater, and widely stocked species were the least likely to be absent upstream of barriers. Sensitive, stream-dependent, and imperiled species were the most likely to be absent upstream of barriers. Can or will fish return if the barrier is removed? Of the 33 dams analyzed, 13 have been removed or modified for fish passage. In all cases, fish species did return, even with only a few years of data. An average of 73% of the absent species returned to the upstream watershed.
This data verifies that dams are among the most profound and definitive causes of native biodiversity losses in Minnesota waters. Thus efforts to remove or modify barriers on our river networks will greatly benefit the fish and mussel communities and improve overall watershed health.
1019: Reconnecting Rivers with Rock Arch Rapids Dam Modifications
Author(s): Neil Haugerud, MN DNR; Amy Childers, MN DNR
Description: Dams around the country are at or exceeding their design life which puts them at risk of failure. Ecologically, dams affect stream health by altering stream processes and blocking aquatic organism migrations. Although dam removal is preferable for restoring river functions, it isn’t always feasible. Accumulated sediment, municipal water intakes, upstream lakes, etc. can deter a full removal of the dam. In such cases, a rock arch rapids design may be implemented that maintains some or all of the original dam’s crest elevation. Rock arch rapids address the blockage of fish migration, eliminate the hydraulic undertows, provide habitat that mimics natural rapids and adds a more natural aesthetic and recreational area to the dam site.
Minnesota has over 55 rock arch rapids projects installed across the state. Recent projects on the Pelican River and Otter Tail River will be highlighted. Discussion of the timeline and hurdles to complete each project will be discussed as well as the design elements that are incorporated into projects to improve fish passage and recreation by the public. Further benefits of these projects will be addressed in the companion talk on fish biodiversity effects of dams.
1107: Evaluating Aquatic Organism Passage at Stream Crossings
Author(s): Brady Schmitz, Stantec; Anna Varian, Stantec
Description: Poorly designed stream crossings can disrupt the natural movement of water, sediment, and aquatic organisms, fragmenting streams and causing erosion and degraded habitat. Natural resources professionals in Minnesota have increasingly recognized the need to assess the impacts of stream crossings both locally in the stream and regionally within the watershed, to prioritize restoration efforts. Within the Coon Creek Watershed District (CCWD) in Anoka County, Coon Creek and Sand Creek are impaired for macroinvertebrate and fish biotic integrity, as designated by the Minnesota Pollution Control Agency. Primary stressors identified as contributing to the aquatic life impairments include excess sediment and nutrients, altered hydrology, poor habitat, and loss of connectivity. The CCWD is actively working to improve stream habitat and connectivity, in addition to reducing runoff volumes and pollutant loading. To better target and prioritize stream habitat and connectivity restoration work, Stantec developed a numeric scoring system to evaluate aquatic organism passage (AOP) at 68 stream crossings and other potential barriers located along the aquatic life impaired reaches of Coon and Sand Creeks. Scoring factors included water velocity, water depth, slope, substrate coverage, and others. Each crossing was assigned a score, which indicated the level of impact to AOP; the scores were then used to prioritize the crossings based on relative severity and position within the watershed. This presentation outlines the methodology used to develop the scoring and prioritization system and presents the results of the evaluation.
1064: Bioengineering and Mussels: Enhancing the Lower St. Croix Ecosystem: Stillwater Riverbank Stabilization and Riverwalk
Author(s): Zachary Morris, AMI Consulting Engineers, PA; Shawn Sanders, City of Stillwater
Description: The project is located along the Saint Croix National Scenic Riverway, in Washington County, Minnesota. The City of Stillwater project includes the stabilization and restoration of approximately 3,700 linear feet of eroded river banks along the western shoreline of the St. Croix River. Incorporated within the shoreline, a new Riverwalk serves as a key connection to the existing St. Croix Valley trail system. AMI Consulting Engineers and the City of Stillwater worked with multiple stakeholders including federal, state, and local agencies. Strict environmental and regulatory compliance was required for this project. Two areas of environmental sensitivity were defined to preserve and protect important and unique cultural and natural resources within the project boundaries, including threatened and endangered species discovered during the environmental review process. Design modifications were then made to avoid impact on multiple species and included conservation measures and creating special habitat features beneficial to the aquatic and terrestrial species.
The construction work was completed in fall 2022. This presentation will provide a recap on last year’s presentation and will focus on the successes/challenges experienced during construction as well as post-construction. An emphasis will be placed on the bioengineering techniques applied, fluctuating water levels, survivability, threatened and endangered species, and stability of the slopes one year after construction.
Concurrent Session V, Track C: Connecting People with the Groundwater They Use
1089: Recent Advances in Groundwater Flow Modeling for Aquifer Protection in Minnesota
Author(s): Trent Farnum, MN Dept. of Health; John Oswald, MN Dept. of Health
Description: As the lead agency for the Wellhead Protection Program in Minnesota, the Minnesota Department of Health (MDH) has been engaged in groundwater flow modeling for the past 30 years. Groundwater models are useful tools that can provide the means to calculate watershed-scale budgets and residence times of both surface water and groundwater. Recent developments at MDH include a shift from local-scale models to regional-scale models along with a standardized approach to uncertainty analysis of well capture zones using Monte Carlo methods in PEST. The shift to regional-scale modeling has been driven by the water resources planning framework in Minnesota, which is based largely on watersheds, and the move to MODFLOW is to create a unified, standardized set of interlocking models that can be used both for wellhead protection area delineations and broader aquifer protection efforts of the uppermost aquifers at time scales greater than the ten-year cycle used for surface waters.
1048: Data Visualization as a Tool to Help Address Inequities Among Private Well Users
Author(s): Deanna Scher, Minnesota Department of Health; TBD-in the process of hiring (will start spring 2023) TBD, Minnesota Department of Health
Description: Minnesota’s Well Code ensures private wells are constructed and sited properly to protect human health and groundwater, but there are limited state and local regulations to help ensure the water is, and remains, safe to drink. Through a grant, the Minnesota Department of Health (MDH) implemented data visualization approaches to target two interventions to help protect the health of private well users overall and those living in rental homes specifically. This presentation will share the general methodology used, findings from working on these two projects, and what has resulted from the work.
Residential property transfer can be an effective time to implement private well testing. The first intervention was to educate real estate professionals about private wells and their role in protecting their client’s health through an online course that offers continuing education credits. Data visualizations informed MDH’s strategy to advertise the realtor training. Data on the number of wells and number of residential sales were combined with vulnerability factors (e.g., socioeconomic vulnerability, well water contaminant levels) to focus outreach efforts.
Renters on private wells are a particularly vulnerable group because there are no state- or local-level ordinances in Minnesota that require property owners to conduct water quality testing in primary residence rental properties. The second intervention includes reaching out to local governments about the lack of required well water testing in primary residence rentals and providing example well water safety ordinance language that could be used to address this public health gap. The MDH used maps combining the number of wells and the number of rental properties with sociodemographic and hydrogeologic vulnerability factors to target outreach to counties with both higher levels of renters on private wells and higher levels of vulnerability.
1043: Findings from the First Minnesota Private Well Forum: A Call for Action
Author(s): Frieda von Qualen, Minnesota Department of Health; Tannie Eshenaur, Minnesota Department of Health
Description: A safe, sufficient, and affordable supply of drinking water is essential to healthy communities and a healthy economy. Yet, about one in five Minnesotans (1.2 million people) have fewer safeguards in place to ensure safe drinking water because their water comes from a private well. Unlike their peers connected to public water, private well owners are responsible for voluntarily protecting and testing their well water and addressing water quality issues.
In May 2023, partners across the state came together to share successful efforts empowering private well users to protect their health; identify and break down barriers to well testing and treatment; and build collaborative efforts with communities, organizations, and agencies to support private well users. Forum participants were connected to private well users in diverse ways—through well construction, maintenance, and sealing; water testing and mitigation; education; local programs and policy; and more.
This presentation will share the key findings and actions established through partners attending the Forum. By attending this session, participants can learn about how they can become part of growing the collaborative effort to ensure all 1.2 million private well users in Minnesota have safe drinking water.
1049: Groundwater Age Distributions in Drinking Water Supply Management Areas
Author(s): Jared Trost, USGS; Kimberly Kaiser, Minnesota Department of Agriculture; Colin Livdahl, USGS; Nikol Ross, Minnesota Department of Agriculture
Description: A measurable chemical "signal" in a groundwater sample from a well can be delayed years to decades from contaminant release or land use change because water moves slowly from the land surface through the groundwater system to a drinking water well. Groundwater age refers to the time elapsed since water entered an aquifer system at the water table. Therefore, knowledge of groundwater age distributions is important for prioritizing and setting realistic expectations for groundwater protection and improvement efforts. Environmental tracer concentrations in groundwater samples are commonly used as a basis for estimating groundwater age distributions in wells, springs, or other groundwater discharge. Common environmental tracers include tritium, chlorofluorocarbons (CFCs), and sulfur hexafluoride (SF6) as well as dissolved gases and noble gases. In this project, environmental tracers were used to estimate groundwater age distributions in dozens of municipal wells across the state. The use of multiple environmental tracers enabled more precise quantification of groundwater age compared to the general classifications (e.g., modern, mixed, premodern) interpreted from a single measurement of tritium. Age distributions in the sampled wells varied widely, ranging from wells with predominantly young water (< 10 years old) to wells with water mainly older than 1953. Groundwater age distributions provide critical information for setting reasonable expectations for the timeframe of when water quality improvements may occur following the implementation of new land management strategies.
Concurrent Session V, Track D: Contaminant Pathways and New Treatment Technologies for Municipal Wastewater
1074: Pilot Trials of Sulfate Reduction in Municipal Wastewater by Chemical Precipitation Technology
Author(s): Sara Post, NRRI - University of Minnesota Duluth; Shashi Rao, NRRI - University of Minnesota Duluth; Mei Cai, NRRI - University of Minnesota Duluth; Lucinda Johnson, NRRI - University of Minnesota Duluth; Chan Lan Chun, NRRI - University of Minnesota Duluth; George Hudak, NRRI - University of Minnesota Duluth
Description: The sulfate standard of 10 mg/L for wild rice water in Minnesota requires industries and municipalities to seek cost effective technology to treat sulfate at relatively low concentrations, such as 50-250 mg/L for municipal wastewater . Natural Resources Research Institute (NRRI) has developed barite precipitation technology to reduce sulfate levels from 50–350 mg/L to below 10 mg/L or other desired levels. Based on the batch lab data, NRRI designed and constructed a trailer-based pilot demonstration system, which was then transferred to three regional wastewater treatment plants to treat water continuously at a rate of 1–2 gallons per minute for a duration of 1.5–2 months each. The wastewater treated included domestic wastewater and a mixture of domestic and industrial wastewater, with sulfate levels ranging from approximately 60 mg/L to 85–115 mg/L and 200–350 mg/L, respectively.
The treatment process successfully reduced sulfate concentrations to below 10 mg/L for all water types and achieved other desired levels of 50, 100, and 150 mg/L using the same process. This technology features a simple treatment process, fast reaction with a short residence time, and is effective at a wide range of temperatures. The addition of chloride to treated water and sludge disposal are the two main concerns that require further investigation. Further work with design firms and water treatment facilities is needed to implement this technology in engineering applications.
1114: Impact of the COVID-19 Pandemic on the Occurrence and Removal of Antibiotics During Wastewater Treatment
Author(s): Zihang Wang, University of Minnesota; William Arnold, University of Minnesota; Huan He, University of Minnesota
Description: The use of antibiotics is a significant problem that impacts the environment and public health. Various antibiotics, such as azithromycin, were applied at greater frequency to treat severely infected patients during the COVID-19 pandemic. Wastewater is an important source of antibiotics to natural water systems. A temporal study of antibiotics in wastewater influents and effluents is needed to assess if the pandemic changed removal rates during treatment and environmental loadings. This work investigates occurrence, concentration, and removal efficiency of antibiotics by WWTPs in Minnesota. From August 2020 to July 2022, monthly influent and effluent samples were collected form four WWTPs with treatment capacities of 22‒172 million gallon/day, serving a total population of ~2, 500,000 people. Samples were extracted and concentrated by solid-phase extraction, and 26 selected antibiotics (sulfonamides, macrolides, tetracyclines, fluoroquinolones, beta-lactams, and uncategorized compounds) were analyzed by LC-MS/MS. Profiles of antibiotics in each class were dominated by the compounds used by humans instead of those solely for animals, i.e., sulfamethoxazole for sulfonamides, azithromycin for macrolides, doxycycline for tetracyclines, ciprofloxacin for fluoroquinolones, and trimethoprim for the other compounds. Wastewater treatment effectively removed certain antibiotics (on average 50.3%‒73.3% for sulfamethoxazole, and 49.6%-95.7% for doxycycline), while negative removals were observed in other cases (possibly due to adsorption of antibiotics to particles/flocs in the influent samples leading to lower recoveries). Concentrations of the prevalent compounds were 0 to ~4000 ng/L in the effluent samples. Based on the antibiotic concentrations, their loadings to the environment and relationships with prescription data will be presented.
1099: Quaternary Ammonium Compounds (QACs) in Wastewater Influent, Wastewater Effluent and Biosolids: Removal Effectiveness and Routes to the Environment
Author(s): Anna Mahony, University of Minnesota; Zihao Lu, Marquette University; Patrick McNamara, Marquette University; William Arnold, University of Minnesota
Description: Quaternary ammonium compounds (QACs) are a group of chemicals used in a wide range of consumer, agricultural, and industrial products, including disinfectants. Disinfectant usage has substantially increased due to the COVID-19 pandemic. Consequently, QAC loadings to wastewater plants and the environment have also likely increased. QACs have been shown to impact the development of antibiotic resistance and may be toxic to aquatic life; therefore, it is important to study the magnitude of increasing QAC concentrations in treatment plants and the environment. Previous studies have shown that > 90% of QACs are removed during wastewater treatment, but these chemicals are present in such high concentrations that low μg/L concentrations are regularly discharged to the environment. Quarterly influent, effluent and biosolid samples were collected from seven wastewater treatment plants with varying sizes and treatment methods in Minnesota and Wisconsin, beginning in June 2021. At two plants, samples were collected along the treatment train to establish a QAC mass balance and assess overall removal. Surface water and surface sediment samples were also collected ~1 km downstream of the wastewater discharge sites. These samples were analyzed for 25 QACs by solid phase extraction followed by analysis by LC-MS/MS. Biosolid samples show high levels of QACs, indicating that land application of biosolids may introduce QACs to surface waters via run-off and leaching. QACs were detected in high ng/L concentrations in the surface waters, showing that effluent also contributes QACs to the environment. This is the first study to date that has quantified the full suite of QACs, including ethylbenzyldimethylammonium compounds (EtBACs), which are present in disinfectants, but have yet to be studied.
1037: Trace Organic Contaminants in Wastewater Effluent: Comparison of Oxidation and Membrane Bioreactor Treatment Technologies
Author(s): Sarah Elliott, US Geological Survey; Richard Kiesling, US Geological Survey; Carrie Givens, US Geological Survey; Charles Christen, St. Cloud State University; Heiko Schoenfuss, St. Cloud State University
Description: With aging infrastructure in Minnesota and across the country, municipalities are looking for cost-effective methods to upgrade wastewater treatment systems. Membrane bioreactors present an attractive alternative to secondary oxidative treatments because they have a relatively small footprint and can handle various wastewater loading conditions. However, little is known regarding the efficiency with which membrane bioreactors can remove trace organic contaminants. In 2022, we collected nine paired samples of primary treated effluent, secondary oxidated treated effluent, and secondary membrane bioreactor treated effluent. Samples were analyzed for 4 alkylphenol ethoxylates, 6 bisphenol analogues, 20 hormones, 110 pharmaceuticals, 82 pesticides, and the microbiome was characterized. Preliminary data for some contaminants and microbiome indicate subtle differences in concentrations and microbial communities among treatment types. Both secondary treatment processes remove bisphenols and alkylphenols similarly; concentrations were at least one order of magnitude less than primary treated effluent samples. A total of 31 pesticides were detected in at least one sample; prometon and fipronil were the most frequently detected, in > 90% of samples. Although results vary by individual pesticide, in many instances concentrations were similar among sample types. Preliminary microbiome data show slightly different microbial communities in both secondary treated effluents, compared to primary, and also compared to each other. Results from this project will provide Minnesota’s water treatment managers with information that can be used to make informed decisions regarding wastewater treatment plant modifications and/or upgrades.