Stormwater Management Trends: 2023 and Beyond

As we return to work after the Christmas break, we can’t help but look forward to 2023 and what the future holds for stormwater management. We reached out to several Contech associates to get their insight. Here is what they had to say.

Increased Use of Performance Verification - Craig Fairbaugh, Regional Regulatory Manager

A Water Environment Federation survey estimates annual spending on stormwater infrastructure in the United States to be between $18 to $24 billion to meet Clean Water Act goals. Regulatory agencies have implemented a host of different stormwater control measures (SCM) to meet these goals and MS4 permit requirements; however, despite the expenditure on SCMs, we are just now making progress on national testing standards and verification programs. Put simply, there has been a lack of performance verification and oversight to ensure that these SCMs are adequately removing pollution from the environment, with some regions evolving faster than others. The Washington State Department of Ecology TAPE program (Technology Assessment Protocol – Ecology) has the nation’s leading field monitoring protocol and verification program, while the New Jersey Department of Environmental Protection (NJDEP) has the nation’s leading lab testing protocols and verification program. Since these agencies’ verification programs have performed rigorous analysis for nearly 20 years, both are being implemented into ASTM standards in the newly formed Committee E64 on SCMs. The intent is for ASTM standards to be the basis for a national verification program, STEPP (Stormwater Testing and Evaluation for Products and Practices). While the TAPE and NJDEP programs have largely focused on manufactured treatment devices, ASTM standards and STEPP verification also intend to assess how well non-proprietary, public domain practices work (bioretention and rain garden media, sand filters, etc.).

In 2023 and beyond, there will be more focus on performance verification for all types of SCMs. Many Midwest and Great Plains jurisdictions are starting to require and reciprocate TAPE and NJDEP approvals, which foreshadows support for ASTM standards and the STEPP national verification program. Performance verification provides much-needed tools for regulatory agencies to help justify public and private spending, and most importantly, these programs raise the bar for SCMs to protect our water resources from stormwater pollution.

Manager Focus on New Stormwater Contaminants in the Next Decade - Jeremiah Lehman, Regional Regulatory Manager

Over the past 20-plus years, we have learned a lot about the impact of various stormwater pollutants on the aquatic environment. With this increased knowledge, we’ve seen an evolution in stormwater regulations and management strategies to handle an ever-growing list of harmful compounds. What began as a general focus on suspended solids and hydrocarbons expanded to include specific forms of metals, nutrients, and bacteria, with each additional pollutant presenting a new set of treatment challenges. In turn, NPDES permittees created more regionally focused regulatory strategies, and the number of water bodies with TMDL listings increased across the nation. This trend will continue in the coming decade; however, the associated management strategies will likely need a significant shift to accommodate the new pollutants on the block.

For years, the prevailing approach to stormwater treatment was relatively simple—identify the culprit and remove it. The next generation of stormwater contaminants will not be so easily subdued—we’re talking about complex organic compounds that exist virtually everywhere in the urban environment and are only recently being recognized for the toll they take. Of particular focus are per- and poly-fluoroalkyl substances (PFAS), a class of compounds used for decades in waterproofing and non-stick applications across hundreds of consumer products that have been linked to environmental health issues such as endocrine disruption and cancer. This past year, the EPA adjusted their drinking water health advisory for two of the most prominent PFAS chemicals, drastically reducing the recommended “safe” concentrations by four to five orders of magnitude from 2016 levels. In addition to their ubiquity, these compounds do not readily break down in the environment, leading them to be referred to as “forever chemicals”. As MS4 permittees begin to plan management approaches for PFAS in stormwater, the standard approach of pollutant removal will be inadequate without an accompanying focus on source control, removing these products from the consumer supply chain and ensuring that they never make their way into the aquatic environment to begin with.

A similar approach is needed for 6PPD-quinone, a derivative of the most common anti-degradant additive found in automobile tires. 6PPD-q makes its way into waterways through particulate from normal tire wear, and very low concentrations have been found to be extremely toxic, especially to endangered and threatened salmon species. While not as persistent as PFAS, this compound’s acute threat to aquatic health combined with the sheer quantity of source material on roadways requires more than the development of innovative treatment practices. To properly manage these newly identified organic pollutants, stormwater professionals will need to develop a coordinated strategy that shifts upstream from the discreet pollutant concentrations in the MS4 and works to limit the availability of these hazardous compounds in the supply chain itself. The regulatory structures needed to accomplish this feat will be the topic of many a spirited debate in the coming years.

Larger Stormwater Detention Volumes - Jeff Smallwood, Region Director

For the past 50 years, we have generally used stormwater detention to maintain runoff rates at pre-developed levels. As time has gone by and rainfall events have intensified, the required detention volumes continue to increase…dramatically so in some parts of the country. Since 2004, the National Oceanic and Atmospheric Administration (NOAA) has been publishing precipitation frequency updates for the various Atlas 14 Volumes (specific regions of the U.S.). This rainfall data is more accurate because it uses more weather recording locations with longer recording periods and more sophisticated statistical methods. A glaring example of the impact of the Atlas 14 data has been seen in Houston, TX, where the 100-year, 24-hour storm was increased by 5-6 inches (45-55%). As a result, the local regulatory agencies have increased the detention volume requirements to 0.75 acre-feet/acre of impervious drainage area for most development projects. In 2023 and beyond, as more data is collected and rainfall intensities continue to escalate nationally, regulatory agencies will be forced to increase detention requirements. While larger land-based options will continue to be an economical choice, underground detention systems will be used even more frequently to store larger quantities on projects in urban areas.  

Regional Projects Blog Prediction – Vaikko Allen, Director, Stormwater Regulatory Management

Any stormwater management professional active over the last two decades, will recognize the phrase “Slow it down, sink it in”, which best captures the low impact development (LID) approach that has been promoted by EPA and others as being the solution to stormwater pollution. This is a great strategy in rural and low-density urban areas where there is plenty of land area available to do small scale, decentralized systems.

But in Phase I communities, prioritizing the use of larger regional scale systems and using small scale systems only where regional facilities are infeasible would bring a range of needed benefits. As compared to green streets and project-by-project, lot-by-lot implementation of green infrastructure, regional facilities that manage stormwater runoff at the neighborhood scale or larger are far more cost effective with economies of scale at every step. There are other benefits as well. From the perspective of a municipality trying to enforce proper design, installation, operation, and maintenance of post construction stormwater control measures, focusing on fewer large systems is a much more manageable workload. This regional approach could also reduce compliance costs for developers where they are able to pay into a mitigation bank or other regional project fund in lieu of implementing and maintaining the most effective controls on site. Regional facilities may be better suited for groundwater recharge when sited appropriately, as compared to many small-scale systems in a densely developed watershed where groundwater migration can cause structural issues, seeps or other issues on neighboring parcels. Integration with water supply or wastewater infrastructure is also more feasible when implemented as relatively few large projects. For example, regional capture and use strategies that store and treat rainwater for municipal irrigation systems, or low flow diversions to the sanitary sewer only make sense at the neighborhood scale.

The bottom line is that there isn’t enough money and probably not enough retrofittable land available to restore and protect receiving waters in our Phase I communities taking a small-scale decentralized approach. Development/redevelopment rates are also insufficient to result in meaningful changes if the bulk of the responsibility for improvements falls to land development projects. We need bold restorative actions to make a difference. My prediction for 2023 and beyond is that stormwater programs will accelerate their shift toward large regional stormwater retrofit projects and will be developing credit trading, fee in-lieu and other alternative compliance strategies to channel private development funds toward these projects. Doing so will accelerate water quality improvements and will ensure that limited funds available for stormwater management are well spent.

Increased Focus on Maintenance - Derek Berg, Director Stormwater Regulatory Management

As 2022 rapidly winds down, it’s a logical time to reflect on what’s been accomplished over the last year in stormwater management, but perhaps more importantly, it’s also an opportune time to look into the future and the important work that still awaits us. Looking ahead, there are numerous topics worthy of our collective attention as stormwater professionals, but none perhaps as widespread as our maintenance, or dare I say, lack of maintenance problem. When it comes to stormwater control measures (SCMs) our dismal track record with maintenance is a problem that spans the gray, the green, the manufactured, the non-proprietary, and everything in between. Unfortunately, the vast majority of our installed SCMs and other stormwater infrastructure is in various states of neglect and in need of maintenance to restore functionality.   As SCMs accumulate sediment, debris, and other pollutants over time their capacity to treat incoming runoff is diminished.   Until they are properly maintained to restore capacity, runoff that is intended to be treated is often bypassed downstream directly into receiving waters. 

What’s the point of investing in and installing all this infrastructure if we are not going to keep it operational? I suspect most of us wouldn’t purchase a new car only to leave it sitting idle in our driveway because we opted not to spend any money maintaining it. The scale of the problem is large and permeates many facets of stormwater management, but here’s hoping 2023 is the year we get serious about funding and enforcing SCM maintenance, not to mention being more mindful about longevity and lifecycle cost during the SCM design and selection process.