Chad Helmle, Tetra Tech’s national lead for green infrastructure, has more than 20 years of experience in the stormwater and watershed management field. Mr. Helmle oversees numerous large and small water resources projects and programs across the United States that explore a broad spectrum of stormwater-related issues, ranging from strategic planning to design and implementation. He has worked on more than 50 neighborhood-scale green infrastructure retrofit design efforts in parks and other public spaces and has helped pioneer new and innovative watershed and best management practices modeling analyses.

Mr. Helmle is passionate about finding innovative solutions to the challenging prospect of retrofitting existing urban landscapes and infrastructure to meet municipal agencies’ compliance or runoff management needs. He continuously works to improve his team’s methods by developing new processes, templates, and tools for creating effective and robust design concepts and modeling approaches for green infrastructure retrofits. He holds a bachelor’s degree in Engineering and Environmental Science from the University of Notre Dame and a master’s degree in Environmental Fluid Mechanics and Hydrology from Cornell University.


What is green infrastructure?

The definition tends to evolve over time and is somewhat subjective, depending on the person you ask and the region you are focused on. Green infrastructure systems commonly are understood to be small-scale stormwater treatment units that leverage biological elements such as plants, amended soil, and storage space to filter and clean the water in a way that mimics or replicates natural hydrologic or watershed processes. You might encounter green infrastructure throughout the country in the form of green streets and bio-retention cells, where they are often seamlessly integrated into the landscaping of public rights-of-way or other common areas. This type of practice can be successfully used as part of new development projects to minimize the impact of increased runoff from impervious areas.

Often, however, we engineers are asked to mitigate the impact of past development by retrofitting our existing infrastructure. This poses a daunting challenge that is likely not tractable by the commonly understood (small-scale) definition of green infrastructure alone. For this reason, I like to push the definition even further to include any infrastructure that is intended to mimic and replicate natural hydrologic and watershed processes, even if it is at a larger scale than what is traditionally referred to as green infrastructure. I would include any infrastructure project geared towards the holistic management of watershed processes.

The whole point of managing a watershed is to intervene in processes that are adversely affecting watershed functions, such as water quality impairments or altered flow regimes. Changes to the environment, while many of them might be natural, are accelerated or amplified by development or other watershed practices. So green infrastructure is an attempt to mitigate that. We are trying to turn back the clock on some pretty powerful forces and build infrastructure that tempers extreme responses and lightens our footprint on the environment.

What are some of the emerging issues regarding stormwater management?

One of the main issues facing stormwater managers at the moment is adequately refining our definition of the end goal. We all know that we want clean water, but the details are critical when it comes to accomplishing that goal. While our industry has made significant progress in recent years, we are approaching a time where our ability to show measurable progress in environmental outcomes is at risk. In stormwater and watershed management, we have some great ideas—green infrastructure being one of them—but our ability to leverage those great ideas to accomplish the goals often laid out in regulatory permits is limited. A big issue is establishing appropriate metrics. For me, appropriate metrics have to include three major characteristics. First, they need to adequately represent a goal that can be clearly recognized—and scientifically supported—as a positive environmental outcome. Second, the metric must be achievable with the tools at our disposal. And third, the metric must be readily measured in the environment. Once you have an appropriate metric, you can accomplish progress with certainty, measure the results, and regularly communicate meaningful outcomes to watershed stakeholders.

These issues are what attracted me to this field. I enjoy working on problems that are large-scale, extremely complex, and require multi-tiered and creative solutions.

What changes have you seen in the technology used to manage stormwater?

We are at a cross roads in the advancement of technology relative to stormwater objectives. With the emergence of the Internet of Things, we can leverage real-time data from deployed sensors. For example, I can know the status of a regional stormwater basin outfitted with this technology at any time. I can see how much water is flowing into the basin and at what rate, view the turbidity both inside and outside of the channel, check the volume of water in the channel, and review the irrigation records for irrigation usage. This information allows us to optimize the design and operations of regional projects and strategies. We have seen how the addition of technology has helped improve our projects, such as our work on the Bolivar Park Stormwater Capture Project. The emergence of smart sensors has a potentially game-changing impact on the industry.

I am excited to say that we have many technical advancements that will help us make significant progress. Increased computational power and individual creative problem solving have created opportunity for our engineers to forge new and powerful analytical and modeling techniques. Real-time monitoring and control hardware will significantly impact the availability of data and opportunity for system optimization. And finally, web-enabled dashboards are poised to help us manage the massive influx of information and synthesize it into easy-to-consume decision support systems.

In addition, technology also has impacted operations and maintenance. For years our clients would send crews out to clean stormwater basins. Several of the basins would be empty. For each visit, they would write down the data on a piece of paper. At the end of the year, they would have thousands of pieces of paper that somebody would have to input into a database. Now the crews have tablets and input the data directly while they are in the field. The tablets are geospatially recognized, allowing us to know exactly where the collection happened and how much sediment was collected in the basin, which enables us to identify trends and track patterns. Now that data is readily available, we are using it to make strategic prioritization decisions about how often the site requires maintenance, allowing us to save our clients time and money.

Where do you see the stormwater management and green infrastructure field going?

As the field continues to move forward, integrated approaches are becoming more and more important. We can no longer manage flooding separately from water supplies, stormwater, and wastewater. Integrated management of water resources is becoming more and more important. Our job is to harness these visionary ideas and deliver practical, implementable solutions for our clients. Integration is the future for water management and is something that we embrace in our projects.