February 13, 2023
By Bill Alms, Project Manager, WSB

Since 2020 Minnesota has experienced drought conditions, with less than average rainfall. The five years before that, Minnesota faced several extremely wet years, and communities were more prone to flooding with average rainfall as much as a foot above average.

This winter, Minnesota has already received well above average snowfall, similar to the winter of 2019-2020. If snow melt trends stay similar this spring to the spring of 2020, it may offer communities a unique opportunity to measure flood storage capacity, identify underperforming outlets, and update flood resiliency plans based on real time data. 

Why This Spring May Provide the Perfect Test Case

Coming off of a wet summer and a snowy winter in the spring of 2020, many communities saw flood storage capacity at its limit. Numerous reservoirs and ponds were high or overflowing, and communities struggled with underperforming drainage outlets. 

Now, this year many of those basins and ponds are low due to ongoing drought and extremely dry conditions – the opposite of 2020. However, with similar snow melts expected in the spring of 2020 and our upcoming spring, this could be an opportunity to reexamine those stormwater basins and assumptions around storm events. 

In short, this may be a rare opportunity to compare real world outcomes with projected models in flood resiliency plans. 

Updating Flood Management Systems 

If outlets flood again this spring with similar snow melts, coming off drought conditions, it is an indication that flood capacity needs to be expanded or elevation increased. It may also indicate where underperforming outlets need to be redesigned or rethought to better reduce flood risk and protect infrastructure. 

Smart technology tools can help determine where to add more storage and how communities can do next step planning on flood mitigation. Communities can install pumps within storm basins, for example, in areas that need more flood storage.

Other Tools to Address Flood Risk During Spring Snow Melts

In addition to updating flood management systems this spring, communities should also ensure they are acting on current flood management plans and tools to prevent flooding and protect infrastructure. This includes zoning areas that need the most attention, educating residents on the importance of removing ice and snow at low points and ensuring storm drains are clear, sandbagging structures if necessary, pumping areas with poor drainage patterns, and more. 

How WSB Can Help

Not sure how to best update flood mitigation plans or where to allocate resources? WSB’s team has the technology, tools, and expertise to address stormwater systems, improve flood resiliency, and implement personalized flood plans that best meet the needs of your community. 

Bill is a project manager in WSB’s Water Resources Group serving clients with their water resources engineering needs. His experience includes planning, design, and construction management, research and inspection of municipal storm water systems, hydrologic, hydraulic, and water quality modeling, watershed permitting submittals, and development plan reviews. He is a technical resource in watershed policy, planning, and capital improvement budgeting.

balms@wsbeng.com | 952.388.4188

November 15, 2022
By Jake Newhall, Project Manager, WSB

Autumn is in full swing. While the arrangements of red, orange, and yellow are stunning, the mass collection of leaves that enter a city’s sewer system after a rainfall can cause serious damage – from clogs to flooding to pollutants in our waterways. 

When the Leaves Fall

When leaves fall, especially when followed by heavy rainfall, leaves on roads, sidewalks, and other impervious services can wash down into city sewers. When the leaves break down and decompose, the nutrients they contain can end up in water. This leads to harmful algal blooms and degraded water quality in rivers, streams, lakes, and other water bodies. 

Additionally, too many leaves washing down stormwater systems can also clog pipes and drains, cause localized flooding, and lead to expensive maintenance costs for cities. 

How can cities proactively address fall foliage and prevent these issues? Here are some tips and tricks. 

Targeted Street Sweeping

The first thing communities can do to avoid these problems is establish a targeted street sweeping plan which analyzes and maps impervious surfaces and high tree canopy coverage areas, as well as their proximity to high-value water resources. Street sweeping is one of the most cost-effective methods to reduce pollutant and nutrient loads to waterbodies and can be very helpful in achieving TMDL goals.

While leaf fall can happen at different times each year depending on several factors including weather, an efficient street sweeping plan prepares communities to manage and strategically target optimum leaf removal.  

Community Education 

Another thing communities can do to help prevent leaves from clogging drains and entering into waterways is to educate residents and private property owners about best practices in autumn. Raking leaves, bagging them, clearing the gutters near private properties, Adopt-a-Drain programs, and properly disposing of the leaves can go a long way in reducing the total amount of nutrients in our waterways and leaves in storm drains. 

How WSB Can Help 

Not sure where to start with creating a targeted street sweeping plan? WSB can help create a customized street sweeping plan that meets your community’s needs. WSB can also help communities reach their pollutant removal goals and execute on water quality management. 

Jake has more than 15 years of engineering experience designing and managing many types of water resources projects, including modeling, planning, design, maintenance programs, and construction. Jake has worked with various municipalities, counties and state agencies to solve challenging water quality and water quantity problems.

jnewhall@wsbeng.com | 763.231.4861

By Jake Newhall, Project Manager, WSB

Extreme rainfall events are occurring with increased frequency. Due to climate and environmental changes, many cities and communities are facing an increased flood risk and must act to protect their communities, residents, and infrastructure. A 2019 report by the National Institute of Building Sciences noted that Natural hazard mitigation saves $6 for every $1 spent on infrastructure resilience.

How can community planners, engineers, and elected officials prepare for and protect their communities from flooding? Here are some guidelines to help reduce flood risk in your community when a storm hits.

Preparing for and Understanding the Weaknesses in Your Systems 

Flood vulnerability and resiliency studies are a process for evaluating a community’s ability to withstand rainfall and identify flood risk. These studies look at the existing systems and determine the risks, and where improvements can be made to protect priority infrastructure. This is vital for communities to reduce risks and flood damage to property and public infrastructure – especially in densely populated areas and those near major roadways. 

As we face more extreme weather events, communities should consider increased rainfall depths and intensities so they can be proactive in system planning. The current storm probabilities available have not been updated since 2014, yet rainfall trends show increases over the last decade. Communities can greatly benefit if they anticipate the future probabilities of storms and construct systems that can handle more intense rainfalls. Using a range of design storms, you can determine flood depths, frequency, duration and assign risk to help prioritize funding. 

Completing a risk analysis and inundation mapping utilizing existing modeling can be a low-cost way to start evaluating your system.

Identifying Projects to Reduce Flood Risk

Locating the areas of risk in your community is critical to flood prevention. That could include finding where your system needs more capacity and storage to reduce flooding, determine what properties are prone to flooding, and creating solutions such as relocation, emergency response, or additional flood protection investments. 

Where collected water goes is important when examining and determining updates for your systems. The primary options are to either pass the water downstream into creeks and rivers, or store it in drainage ponds, underground systems, or other storage areas. Another option is to reduce the impervious footprint to reduce the amount of runoff that is generated. Emerging technology allows for predictive rainfall systems that can generate additional storage ahead of a large rainfall event by releasing water early and prior to a peak event through a critical area.

The risk with moving the storm water downstream is the possibility of flooding and eroding the creeks and rivers. If conveyance capacity is increased to the downstream system, it is necessary to make sure that proper measures are taken to avoid flooding and erosion that can harm waters and ecosystems. Water storage options like drainage ponds or underground storage, are options for many communities to utilize. Balancing needs, functionality, and the cost of storage and land is important for communities to explore. Water quality and pollutant removals can be a secondary benefit of many stormwater storage systems that can help communities achieve other goals at the same time.  

Finally, for most communities, the needs often outweigh the budget available to accomplish them all. WSB helps clients navigate flood vulnerabilities, pursue grant funding, and help make informed decisions that best serve a community’s individual needs. 

Jake has more than 15 years of engineering experience designing and managing many types of water resources projects, including modeling, planning, design, maintenance programs, and construction. Jake has worked with various municipalities, counties and state agencies to solve challenging water quality and water quantity problems.

jnewhall@wsbeng.com | 763.231.4861

By Earth Evans, Director of Water Resources, WSB

The Minnesota Department of Natural Resources (DNR), in coordination with local watershed districts, has developed updated draft Federal Emergency Management Agency (FEMA) flood risk maps and hydrologic and hydraulic analysis. The affected area includes the floodplains in the hydrologic unit code 8 (HUC8) subbasin. HUC8 includes portions of Ramsey, Washington, Anoka, and Hennepin Counties.

The updated hydrologic and hydraulic analysis is based on National Oceanic and Atmospheric Administration (NOAA) Atlas 14 precipitation events across the United States. The draft flood hazard maps may expand existing FEMA regulated floodplains within the Twin Cities metro due to the higher precipitation depth and frequency. The FEMA map updates will likely take effect in 2023. This is the first step in the process to develop updated FEMA Flood Insurance Rate Maps.

It is important that city officials pay close attention to these updates. The draft FEMA floodplain boundaries may increase with this analysis, which may reduce developable area in a municipality, increase the number of properties that are required to purchase flood insurance, and require property owners to change the type of flood insurance they possess. Additionally, the DNR is requiring that each community update their ordinance to require mitigation for fill in the modeled storage areas upstream of FEMA floodplains. 

Currently, the maps are for city officials only. City staff should cultivate a strong understanding of the implications now, before the maps become open for public comment. During the next month, there will be opportunities for city staff to connect with the DNR staff, review floodplain limits, and understand the implications on developable area and properties that will require flood insurance within the community. 

WSB can help navigate this process and facilitate meetings with DNR Floodplain Staff. City officials are encouraged to reach out to Earth Evans, WSB’s Director of Water Resources with questions.

Earth has 20 years of experience as a project engineer and project manager on technically diverse projects in water resources. She is a technical resource in hydrologic and hydraulic modeling, flood damage reduction and floodplain modeling, water quality modeling and evaluation of best management practices, permitting, and hydraulic design. She has has worked extensively with MnDOT and state aid requirements and coordinated with local, regional, and state permitting agencies.

eevans@wsbeng.com | 763.231.4877

By Jake Newhall, Project Manager, WSB

Minnesota’s Municipal Separate Storm Sewer System (MS4s) are currently in the process of applying for coverage under the revised MS4 General Permit. The updated MS4 General Permit creates changes in the ways that MS4 permittees will operate, starting with modifications that address procedural and programmatic changes needed to comply with updated rules. 

One of the main changes is new performance-based responses to Total Suspended Solids (TSS) and Total Phosphorus (TP); including a TMDL assessment to identify and prioritize activities to achieve reductions. WSB’s SWAMP system helps to address these new regulations by streamlining TMDL compliance through tracking and documenting improvements that have been completed to date or since the baseline of TMDL development. The SWAMP system also helps target subwatersheds that are underperforming or lacking the necessary treatment to meet water quality goals. SWAMP improves efficiency by saving time on planning and modeling when developing an efficient plan to address TMDL requirements.

Aside from improving compliance with new MS4 TMDL requirements, SWAMP continues to help address existing MS4 requirements.

• Estimate TP and TSS reduction from existing ponds and BMPs
• Prioritize inspection and maintenance activities related to ponds and BMPs
  • Ensure standard operating procedures are in place and stormwater management features continue to function as designed
• Inspection and maintenance activities are automatically updated and reflect real-time information
• Tracks and stores completed activity records for on-demand reporting

Jake has more than 15 years of engineering experience designing and managing many types of water resources projects, including modeling, planning, design, maintenance programs, and construction. Jake has worked with various municipalities, counties and state agencies to solve challenging water quality and water quantity problems.

jnewhall@wsbeng.com | 763.231.4861

By Earth Evans, Director of Water Resources, WSB

The new 2020 MS4 General Permit is now available from the Minnesota Pollution Control Agency (MPCA). While there are lots of familiar questions in the permit, the Total Maximum Daily Load (TMDL) application form is new territory for many MS4s. The goal of the TMDL application form is to document progress towards meeting waste load allocations (WLA) for impaired waterbodies that the MS4 discharges to. Unlike previous applications that allowed for a simple qualitative tracking of progress (i.e. listing education programs, ordinance updates, etc.), it is now a requirement to provide documentation of quantitative load reductions, for example how many pounds of phosphorus does your new infiltration basin remove? 

The MPCA has developed a guidance document and a template TMDL spreadsheet unique to each MS4.

But like any new process, there may be some growing pains, so we recommend starting early.

Below are some steps to follow for a smooth transition. 

1. Identify the subwatersheds in your jurisdiction that are tributary to the TMDL waterbody.
2. Gather information on structural BMPs that have been constructed or retrofitted in the subwatershed. 
   • Did you complete a pond maintenance project?
   • Have you coordinated with a Watershed District, Soil Water Conservation District or other agency to construct a BMP?
   • Did you include BMPs with a street reconstruction project?
   • Street sweeping?
   • Have you constructed streambank or slope stabilization repairs?
3. Model to determine the BMP load reduction
4. Input the load reductions into the TMDL spreadsheet

The spreadsheet will need to be updated annually with the MS4 permit application. The bulk of the effort will be invested with this first application form. 

Now that the spreadsheet is updated and there is an understanding of what progress has been made towards meeting waste load allocation and water quality improvements – the next step is outlining a plan to achieve compliance. Subwatershed Assessments are a great method for evaluating, ranking and prioritizing BMPs to continue progress towards WLAs that aren’t met. These assessments focus on identification of drainage areas with little to no stormwater treatment or opportunities for large increases in treatment.  These assessments help the MS4 achieve TMDL requirements or keep waterbodies from being added to the impaired waters list.

The BMP load reductions and cost from the Subwatershed Assessment can be used to apply for grant funding. Reach out to partnering agencies, watersheds, conservation districts to gain momentum, buy-in and funding. There are multiple grants that prioritize funding for projects that work towards compliance with TMDLs.

Earth has 20 years of experience as a project engineer and project manager on technically diverse projects in water resources. She is a technical resource in hydrologic and hydraulic modeling, flood damage reduction and floodplain modeling, water quality modeling and evaluation of best management practices, permitting, and hydraulic design. She has has worked extensively with MnDOT and state aid requirements and coordinated with local, regional, and state permitting agencies.

eevans@wsbeng.com | 763.231.4877

By Jake Newhall, Project Manager & Pete Willenbring, Vice President, WSB

Approaching winter conditions mean more salt in stormwater systems

Chlorides in our local bodies of water have become a rising concern in recent years.  As winter weather approaches and causes icy conditions, our parking lots, roadways and sidewalks are treated with salt to melt snow and ice.

Salt creates safer winter driving conditions, but the environmental impacts of salt use are raising concerns on the long-term effects on fisheries, plant life and surrounding wildlife. The salt used to treat our roadways and pedestrian areas contains chloride that dissolves when mixed with water.  This has resulted in increased chloride concentrations in many lakes, streams, and wetlands.  The elevated chloride levels are high enough in some cases to cause significant environmental impacts.

Removing chloride from water is possible, but the technology is incredibly expensive, and disposal of the chloride removed is a challenge. The primary way to remove chlorides requires high-tech reverse osmosis filters. This is not unlike the challenges presented in treating ocean water for potable source water.  

Monitoring the runoff and impacted surface water bodies in areas where heavy salt application is occurring is allowing us to gain a better understanding of the effects of chlorides on our environment and how communities can manage application rates to balance public and environmental safety.

In recent years, WSB has been working closely with state and local agencies to monitor and track the application, runoff concentrations, and ultimate impacts of chlorides in various locations. The goal is to develop a better methodology to manage the application, potential chloride disposal opportunities, and minimize environmental impacts. Through this research, we’ve been exploring ways to reroute chloride-saturated runoff away from local surface waters and BMPs and protect them from elevated concentrations.

As we continue to monitor and evolve our understand of chlorides, we are developing several initiatives with cities, watersheds, and the Metropolitan Council that will allow us to balance future management strategies, public safety, and environmental impacts of chlorides.

Jake has more than 15 years of engineering experience designing and managing many types of water resources projects, including modeling, planning, design, maintenance programs, and construction. Jake has worked with various municipalities, counties and state agencies to solve challenging water quality and water quantity problems.

jnewhall@wsbeng.com | 763.231.4861

Pete is a principal and co-founder of WSB. He is a professional engineer, with over 30 years of experience providing consulting services to over 100 city, county, state, and federal clients. Pete has expertise in most fields of civil engineering, but is widely recognized to have developed special expertise in the fields of water resource and environmental engineering, project management, design, and planning.

pwillenbring@wsbeng.com | 612.360.7188