Optimizing Remediation for Environmental Flows

Optimizing Remediation for Environmental Flows

The most common approach to Superfund, as well as other site, remediation is primarily focused on the most pressing issue at hand—removing contamination and achieving compliance. However, as ecologists and hydrogeologists, we have the experience and technical knowledge to not only address these issues, but to optimize our solutions in a way that both contributes to the site’s overall environmental wellbeing and saves our clients money. One way to do this is to keep in mind the importance of environmental flows and to attempt to maintain them with our remediation techniques when possible.

Significance of environmental flows

Now more than ever, in light of changing climate conditions that have resulted in floods, droughts, and wildfires, maintaining environmental flows is a priority for anyone involved in resource management. Environmental flow, according to The World Bank Group, refers to the “quality, quantity, and timing of water flows required to maintain the components, functions, processes, and resilience of aquatic ecosystems.” This is also commonly referred to in the U.S. as an “instream flow.” Freshwater resources are vital for maintaining a healthy community, and preserving their capability to maintain a healthy balance means disrupting environmental flows as little as possible.

Unfortunately, many of our efforts that contribute to the health of the environment and the communities that rely on these resources, such as agricultural or urban use, hydropower, and groundwater remediation, can negatively affect natural environmental flows. This is particularly true in remediation if groundwater that has consistently flowed to nearby surface water is withdrawn for treatment and never replaced. Modifying environmental flows in this way has resulted in reducing the flow of many rivers or seasonally altering them, which translates into a change in the frequency and magnitude of flows as well as the severity of drought related impacts. As factors outside our direct control, such as prolonged stretches of high temperatures and little rain, continue to have a substantial impact on environmental flows, remediation practitioners will need to pay increased attention to how their work affects the delicate balance of surface water.

Tailoring remediation to preserve flows and save money

In one of our recent projects at a Superfund site, our team had the opportunity to optimize a pump-and-treat system that was currently in use. The site happened to be located next to the headwaters of a river that is the center of a large watershed area, incorporating several streams and a reservoir. With contaminated groundwater regularly leaching into the river, preventing that negative effect was one of the top priorities associated with remediation, and a collection trench was built in order to catch water migrating from the source area to the river. That groundwater was then pumped to an on-site treatment facility for pre-treatment, and then on to a regional sewage treatment plant.

While this approach was proving effective in preventing contamination of the river due to organic compounds from the influx of contaminated groundwater, it was also having a significant effect on the river’s environmental flow. Even so, the client could have continued operations in the same way they’d been doing for years, as it wasn’t in violation of any regulations or consent orders. However, in our assessment of the site, we determined that there was a way to modify the management of this groundwater that would benefit both the river and the client. We offered a solution wherein the treated groundwater, instead of being pumped to the regional sewer facility, would be injected back into the site in a way that allowed it to run into the river as it naturally would. This effectively allowed us to begin restoring the natural balance of the river’s environmental flow, along with saving the client thousands in annual fees that were being paid to the sewer facility, and potentially enhancing cleanup time frames.

Today’s landscape of remediation is changing in ways that require us to look more closely at the techniques we’re implementing on any given site. In this case, both the project team and the client saw that there would be a significant return on investment in terms of savings and contributions to the health of the local ecosystem if alternative solutions were considered. The success here is a good reminder of the opportunities we have to benefit our clients and the environment by cultivating awareness of the importance of variables like environmental flows.

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Senior Technical Manager
Hydrogeology

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