Lefers, Amber

Amber Lefers is the Water Resources Practice Leader at AE2S and in her role at AE2S, she helps communities prepare for the wrong amount of water. She calls Madison, Wisconsin "home," where she lives with her wife and two teenage kids. Her work passions include translating the often-complex world of flood and drought risk to community members and elected officials, urban flood risk assessments, FEMA floodplain permitting, and hydrology and hydraulics. In her free time, she plays Ultimate Frisbee, runs and lift weights, grows orchids, and spends time with her family!

Titles from this speaker

Description: Burnsville Minnesota Stormwater Risk Assessment, Resiliency Study, and Twin Lakes...

Burnsville Minnesota Stormwater Risk Assessment, Resiliency Study, and Twin Lakes Flood Risk Reduction Improvement Project

Abstract

Communities have extensive GIS data that can be used as input to storm sewer models. This presentation will walk through how communities can use this data to help plan, predict and mitigate flooding within their communities. The City of Burnsville (26.87 sq. mi.), like many communities throughout the Minnesota Minneapolis-St.Paul Metro, have a 1D City-Wide XPSWMM model. The City wanted to upgrade their 1D model into a 2D model to create a model with a higher accuracy for their complex storm sewer network. Burnsville was the first community within the Metro to develop a City-Wide 2D model. The 2D model allowed the City to have a better understanding of their flood risk that a traditional 1D model would not be able to identify (i.e. surface flow velocities, erosion susceptibility of overland flow areas, emergency overflow capacity issues in residential areas, and showing where overland flow conveyance points are most critical). The flood rasters and associated output data from the 2D model were then taken and integrated into a custom-built Resiliency Model evaluating the Consequence of Failure (CoF) versus the Likelihood of Failure (LoF) criteria, building on the techniques often used in water main and sanitary sewer asset management programs. The various CoF and LoF parameters were weighted based on input from City staff to determine the most critical aspects of their system such that the resiliency model would take these factors (weights) into account to determine which areas are the most critical to construct flood risk reduction projects. This approach removed any bias from the evaluation process allowing the City to develop a guiding document/living model the City can use for future planning & mitigation projects. All of the processes are fully dynamic allowing the 2D model and Resiliency Analysis to be rerun to re-prioritize the zones annually. Based on the outcome of the resiliency study, the city moved directly into constructing a large flood risk reduction project for a high-scoring area of the City's system. The Twin Lakes Flood Risk Reduction Project involved three major design components to alleviate flooding risk along a small chain of lakes. Given that these lakes drain to other flood-prone areas, at a minimum the project required that overall peak flows were maintained. The already-built city-wide 2D SWMM model allowed the design team to quickly develop the hydraulic design that reduced flooding in the Twin Lakes area and maintained downstream flows. Currently, evaluation of the next flood risk reduction project for a critical area is ongoing with design of that project expected to occur in 2022.

This paper was presented at the WEF Stormwater Summit in Minneapolis, Minnesota, June 27-29, 2022.

SpeakerLefers, Amber

Presentation time

11:45:00

12:15:00

Session time

10:45:00

12:15:00

Session number02

Session locationHyatt Regency Minneapolis

TopicAsset Management, Flooding, Resiliency

Author(s)

A. Lefers

Author(s)A. Lefers1; J. Klabo2

Author affiliation(s)Advanced Engineering and Environmental Services Inc1; WEF Member Account2;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Jun 2022

DOI10.2175/193864718825158470

Volume / Issue

Content sourceStormwater Summit

Word count16

English Coulee Water Quality Renewal Plan

Abstract

The English Coulee meanders through Grand Forks, North Dakota and has many important uses to the City not only drainage and interior flood protection storage but also pedestrian walking / biking corridor and active recreation opportunities such as ice skating and paddling. Given that the English Coulee serves a watershed over 50 square miles that is dominated by agricultural land use, the coulee has been plagued by issues related to E coli and phosphorous. Further, as Grand Forks continues to grow, urban runoff quality is also providing significant loading. Finally, a significant hydrologic / hydraulic alteration to the English Coulee was made about 20 years following the catastrophic 1997 Red River flood that destroyed much of the City - the English Coulee Diversion was constructed as part of the interior flood protection system that aids in protecting the City from Red River floods. This diversion cuts off much of the agricultural watershed but also reduces the potential for high springtime flows to flush sediment and nutrients that have accumulated in the coulee within the City. The stagnant water conditions throughout much of the summer combined with the likely high nutrient concentrations create severe aesthetic and odor issues related to algal blooms and anoxic conditions. While the coulee is listed as an impaired 303(d) waterway, the City decided to begin their own multi-phase initiative to renew the coulee given its benefit to the community as a recreational resource. The first phase of the project focused on answering the question 'what could be done?'. To answer this question, the first phase involved three key components: 1) public outreach and engagement, 2) water quality monitoring and modeling, and 3) hydrologic / hydraulic monitoring and modeling. A unique approach to public engagement was used with signs along the coulee with QR codes that pedestrians could scan and bring the online survey up on their phones. The public engagement survey received over 500 responses with an overwhelming response that the community wanted to see the Coulee's water quality improved. Water quality monitoring was also completed for numerous parameters that confirmed the community's observations nutrients (namely phosphorous), suspended sediment, and E coli were all very high throughout the year. Water level data was also collected at several locations that indicated that FEMA's hydrologic and hydraulic analysis did not reflect the complexity of the coulee hydraulics, illustrating the need to create a more robust hydrologic / hydraulic model of the coulee system to evaluate potential watershed and channel / dam modifications. The second, ongoing phase of the English Coulee Renewal Plan aims to answer the question 'What should be done?' with subsequent phases aimed at implementing projects to improve water quality in the coulee.

This paper was presented at the WEF Stormwater Summit in Minneapolis, Minnesota, June 27-29, 2022.

SpeakerLefers, Amber

Presentation time

11:45:00

12:15:00

Session time

10:45:00

12:15:00

Session number13

Session locationHyatt Regency Minneapolis

TopicHydrology & Hydraulics, Public engagement, Water Quality

Author(s)

A. Lefers

Author(s)A. Lefers1; M. Parvey2; M. Quinn3; A. Boe4; C. Edwards5; H. Holmberg6

Author affiliation(s)Advanced Engineering and Environmental Services Inc1; City of Grand Forks2; WEF Member Account3; Advanced Engineering and Environmental Services Inc4; WEF Member Account5; WEF Member Account6;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Jun 2022

DOI10.2175/193864718825158469

Volume / Issue

Content sourceStormwater Summit

Word count7

Description: Flood & Drought Risk Assessment and 2022 Flood Response for Billings, MT...

Flood & Drought Risk Assessment and 2022 Flood Response for Billings, MT Water Treatment Plant Along the Yellowstone River

Abstract

The Billings, MT, USA water treatment plant (WTP) is located adjacent to the Yellowstone River and serves a population of over 100,000 people. FEMA floodplain maps show much of the WTP within the 100-year floodplain. Further, previous low water events had created difficulty to use the preferred side channel intake. Plant staff were concerned that future high and low water events on the Yellowstone River could have significant impacts to WTP operations. It was also unclear which facilities were most at risk and what would be the most effective emergency response plan. AE2S prepared a hydrologic and hydraulic model of the Yellowstone River to evaluate that risk. The analysis showed that the WTP was at risk to both high and low water events. Following the analysis, the 2022 flood of record occurred, and the risk assessment helped plant staff prepare and respond to maintain water supply to the city.

The Billings, MT, USA water treatment plant (WTP) is located adjacent to the Yellowstone River. A hydrologic and hydraulic study of the Yellowstone River was completed to quantify risk to WTP operations from both high and low water level events. Shortly after completing the risk assessment, both extreme low and high water levels occurred on the Yellowstone, including the 2022 flood of record. The risk assessment helped plant staff prepare and respond to these events.

SpeakerLefers, Amber

Presentation time

09:00:00

09:20:00

Session time

08:30:00

10:00:00

SessionUnprecedented Weather Events: Planning for Organizational and Operational Resiliency

Session locationRoom N426b - Level 4

TopicIntermediate Level, Resilience, Disaster Planning and Recovery, Utility Management and Leadership

Author(s)

Lefers, Amber

Author(s)A. Lefers 1; A. Lefers 1 ;

Author affiliation(s)Advanced Engineering and Environmental Services 1; Advanced Engineering and Environmental Services 1 ;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159072

Volume / Issue

Content sourceWEFTEC

Word count20

Shifting Focus for the Future: How to Adapt a Current Plan to Create a Resilient Flood Protection System - Case Study Grand Forks, ND South End Drainway and Levee System

Abstract

Following the catastrophic 1997 Red River of the North (RRN) flood, the City of Grand Forks, North Dakota and the US Army Corps of Engineers designed and constructed a massive flood protection system that involved an extensive levee and floodway system along the RRN and significant interior drainage improvements, including the South End Drainway (SED), Closure Structure, and Pump Station. At the time of the design and construction, much of the City's south end was undeveloped, so numerous assumptions had to be made about future land use and anticipated stormwater management. Over the past 20 years, both recent and anticipated future development density exceeds what was anticipated for design. Recently, a rapid snowmelt combined with heavy spring rainfall occurred in Spring 2022 that created flooding conditions throughout the City's south end that were more severe than expected, suggesting that the City had more vulnerabilities in their interior drainage system than previously thought. To update the master plan for the South End Drainway watershed, substantial work was needed to accurately reflect current hydrologic and hydraulic conditions. This work included: 1.Installing rainfall and water level monitoring equipment throughout the watershed since previous work around the City indicated that rainfall-runoff responses were more complex than typical watersheds. 2.Creating a new XP-SWMM two-dimensional (2D) hydrologic and hydraulic model that used a combination of rain-on-grid and subcatchment modeling. The model covered about 7.8 square miles (20 square kilometers) and included over 3,100 links to represent the underground storm drain system. 3.Creating an hourly, continuous (almost 75 years) hydrologic simulation simulating rainfall, snowpack accumulation, and snowpack depletion to determine the most severe historical events. 4.Reviewing both the timing and magnitude of RRN flood stages to determine the likelihood of a severe hydrologic event on the interior drainage system combined with a gate closure / pumping condition. 5.Assessing the presence and implications of trends in hydrologic severity for both high RRN stages and severe rainfall / snowmelt conditions within the SED watershed, and 6.Determining the 1% Annual Chance Event (ACE) for both a spring snowmelt / rainfall event with gates closed and summer thunderstorm with gates open conditions. Once the updated XP-SWMM model was created, it was discovered that both spring and summer conditions exceeded the City's maximum allowable elevations along the SED and that the gates closed with spring rainfall and snowmelt occurring was the worst-case scenario. Based on the flat hydraulic grade line during the worst-case scenario, it was evident that either the system did not have sufficient storage or that the existing pumps lacked sufficient capacity. Master planning work began with developing a conceptual full build-out land use plan for the entire planning area. The full build-out land use plan confirmed that anticipated land use densities and corresponding impervious area amounts would be much higher than originally assumed. The current conditions XP-SWMM models were updated to reflect full build-out land use and a variety of stormwater detention standards and routing changes were explored to determine the optimal approach to lowering SED flood elevations to below the maximum allowable elevations while also accommodating future development in the watershed. Key conclusions from the evaluation were that: 1.The 1% ACE summer thunderstorm became the controlling event indicating that development expansion in the City's south end would have a nuanced impact on the performance of the SED. 2.With the storage needed to control the 1% ACE summer thunderstorm to near the maximum allowable elevations in the SED, the maximum 1% ACE spring snowmelt / rainfall event flood elevations would lower substantially because the increase in storage more than offset the modest hydrologic change from frozen ground to impervious cover. 3.The needed storage for new development was two to five times greater than the City's current standards, but this increased storage provided for new development would avoid tens of millions of dollars in new City-funded infrastructure. 4.Feasible routing changes (including pumped diversions) had only modest benefits or impacts whereas storage provided a much more efficient solution to reducing flood risk in the SED. The findings of this study are useful for the stormwater professional community because the study demonstrates: 1.Using statistical probability and a variety of analysis approaches to determine the 1% annual chance event for a variety of conditions (summer thunderstorm and spring / snowmelt). 2.The need to revisit and update stormwater master plans since development densities are typically much denser than anticipated as recent as 10 to 20 years ago, 3.The benefits of 2D modeling in flat topography to accurately simulate runoff and flood peaks reaching critical drainage infrastructure, 4.The benefits of collecting monitoring data to validate models that are rarely checked against data, and 5.Balancing development and City costs for storm drainage and flood protection infrastructure to create an optimal solution that alleviates existing flood risk and provides a resilient plan to shifts in hydrology as land use and climate changes.

The South End Drainway in Grand Forks, ND, USA is part of the City's overall flood protection system that was constructed following the catastrophic 1997 Red River flood. The City's south end is also experiencing heavy development growth that could worsen flooding risk to existing developed areas. A previous master plan had been developed that assumed a much lower density for future development than has been occurring, so a new South End Flood Protection System Master Plan was developed.

SpeakerLefers, Amber

Presentation time

08:30:00

09:00:00

Session time

08:30:00

10:00:00

SessionTools for Urban Flood Management and Forecasting

Session number312

Session locationRoom 343

TopicCSO & SSO Planning and Mitigation, Intermediate Level, Resilience, Safety, and Disaster Planning, Stormwater and Green Infrastructure, Watershed Management, Water Quality, and Groundwater

Author(s)

Lefers, Amber

Author(s)A. Lefers1

Author affiliation(s)1AE2S, WI

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159704

Volume / Issue

Content sourceWEFTEC

Word count31

Description: Using 2D Modeling to Improve Large-scale Urban Stormwater Modeling to Support...

Using 2D Modeling to Improve Large-scale Urban Stormwater Modeling to Support Instream Water Quality Improvement

Abstract

The English Coulee in Grand Forks, ND, USA is severely impacted by non-point source pollution from both agricultural and urban runoff, exacerbated by a flood protection diversion that was constructed following the catastrophic 1997 Red River flood that significantly altered the hydrology of the Coulee within the City. The greenspace corridor along the Coulee serves as a major recreational feature through the City with a major hospital, the University of North Dakota, and single family homes adjacent to the Coulee. Through a successful public outreach program in 2021, the City confirmed that City residents supported investing in the Coulee to improve water quality. Hydrologic (water levels and rainfall), water quality (multiple parameters), and sediment quality (multiple parameters) have been collected over the last few years. Because of the extremely flat topography, 2D rain-ongrid modeling with XP-STORM was required to accurately calibrate the hydrologic and hydraulic model.

The English Coulee in Grand Forks, ND, USA is severely impacted by non-point source pollution, exacerbated by a diversion that was constructed following the catastrophic 1997 Red River flood. Because of the extremely flat topography, unique modeling approaches were needed to accurately reflect the hydrology and hydraulics of the English Coulee to evaluate water quality improvements. Substantial hydrologic and water quality monitoring and public engagement was also completed.

SpeakerLefers, Amber

Presentation time

08:30:00

08:50:00

Session time

08:30:00

10:00:00

SessionFlood Modeling Case Studies

Session locationRoom S501d - Level 5

TopicIntermediate Level, Resilience, Disaster Planning and Recovery, Stormwater and Green Infrastructure

Author(s)

Lefers, Amber

Author(s)A. Lefers 1; L. Severson 1 ; C. Edwards 2; S.R. Schauer 3; L. LaMoore 4;

Author affiliation(s)Advanced Engineering and Environmental Services 1; Advanced Engineering and Environmental Services 1 ; Advanced Engineering and Environmental Services 2; 3; 4;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159056

Volume / Issue

Content sourceWEFTEC

Word count16