Sustainable Groundwater Treatment System Redesign

Leveraging innovative and sustainable design strategies, TRC recently upgraded an aging groundwater pump and treat system in New York State. The system, which has been operating since 2002, recovers chlorinated volatile organic compounds (CVOCs) from a deep bedrock well and is effective in capturing and containing trichloroethylene (TCE) within the Site boundaries. The upgrade was initiated to replace aging equipment and determine if alternate treatment methods could be used to reduce operating costs, the frequency of site maintenance visits and the environmental footprint of the treatment system.

With our expertise in water and wastewater treatment design, and our commitment to green and sustainable remediation practices, we implemented a new system that will deliver cost savings and environmental benefits for years to come.

Project Challenge: An Outdated and Inefficient System

The old treatment system included initial filtration using two bag filter housings plumbed in parallel, followed by two air strippers plumbed in series. The air strippers were effective in reducing the initial high TCE concentrations down to discharge standards and the treatment system has removed approximately 1,270 pounds of CVOCs since 2002. However, the mass removal rate diminished over time, with influent concentrations dropping to less than 100 mg/L. With air strippers over 20 years old regular maintenance was required for the system to remain active, often needing two or more site visits per month. The reduced contaminant loading rate and frequent maintenance of the air strippers made the system inefficient, requiring more labor and electricity use than warranted. Additionally, due to the age of the system, no effective telemetry was installed to notify of system alarms or shutdowns, resulting in extended system down times and operators arriving at the site to find the system in need of repair.

Solution: Sustainable Redesign and System Upgrades

To optimize the deteriorating plant, TRC updated the treatment system design to remove the air strippers and replace them with two granular activated carbon (GAC) treatment vessels. The GAC vessels do not have moving parts, which reduces the electricity consumption by removing the two sump pumps and air fans associated with the air strippers. A new equalization tank and transfer pump installed to collect the recovered groundwater and pump it through the bag filters and GAC vessels prior to discharge to a local surface water body. This modification is expected to extend the longevity of the groundwater recovery pump by removing the variable backpressure the pump was exposed to when the pressure drop across the bag filters increases.

Some other notable system upgrades include:

• Installing a new pressure transducer and variable frequency drive in the extraction well to automatically adjust pumping speeds while maintaining a set pumping level.
• Installing a new programable logic controller (PLC) to control system operations and log operating data.
• Equipping the system with modern telemetry to allow for remote inspection, shutdown and alarm notifications.
• Equipping the room with a perimeter drain and sump to recover any spilled water, provide alarm notifications and remotely shutdown the system if the sump fills with water.
• Installation of a valving system to swap the GAC vessel order, allowing for vessels to change from the lead/lag positions.

Results: Cost Savings and GHG Reductions

The new system configuration is expected to reduce the frequency of required maintenance by half, to a once per month schedule. The frequent air stripper servicing visits will be replaced by two annual GAC change out events. The new system design will reduce electricity use by approximately 40% by removing the air stripper sumps and fans and replacing them with a 1.5 horsepower transfer pump. The re-design and upgrades are expected to reduce annual operations and maintenance (O&M) costs by nearly $35,000.

The system upgrades will have a significant impact on greenhouse gas emissions by reducing anticipated emissions by 36%, or approximately 17 tons of carbon dioxide annually and 170 tons over the next 10 years of operation.

TRC Can Help

TRC’s Green and Sustainable Remediation (GSR) CORE team is dedicated to improving the environmental footprint of our remedial actions, while maintaining protective remedy. The GSR CORE team can help quantify and develop the environmental footprint for your remedial strategy using the EPA’s Spreadsheets for Environmental Footprint Analysis (SEFA) program and identify ways to enhance sustainability using best management practices and site-specific solutions. TRC’s Wastewater and Remediation Process Design CORE team compliments these efforts by focusing on treatment system design, installation oversight, O&M and system optimization as well as resiliency and sustainability assessments, all while meeting emerging contaminant treatment challenges.

For more information, please contact one of our experts below:

• Howard Nichols, PE, Senior Engineer & Project Director, HNichols@trccompanies.com
• Stefanie Pantazis, ENV SP, Senior Engineer & Project Manager, SPantazis@trccompanies.com
• Lauren Harpold, Environmental Engineer I, LHarpold@trccompanies.com