PFAS Central Treatment System

Former DoD Facility - Michigan

About

Four sites at a former AFB were originally opened due to VOC impacts. Two purge well fields and two P&T systems were constructed in the 1980s and 1990s to capture and treat groundwater migrating from the sites. Recent investigations identified PFOA and PFOS in groundwater at concentrations above regulatory cleanup criteria within the capture zones of the purge well fields. In 2018, an LGAC groundwater treatment system known as the Central Treatment System (CTS) was constructed to treat the groundwater recovered from two purge well fields. Bay West provided oversight while the CTS was being constructed and has operated, maintained, and optimized the CTS since it was brought online in August 2018.

Project Scope

 PFOA/PFOS Groundwater Sampling
 Groundwater Modeling
 Contaminant Fate and Transport Analysis
 Purge Well Field Capture Analysis
 Pump and Treat System Optimization, Operation and Maintenance
 Pump and Treat System Discharge Permit Compliance Sampling
 Preparation and Submittal of Daily and Monthly Discharge Monitoring Reports
 Preparation of Annual Remedial Action Operation Reports
 Meeting Agenda and Presentation Development
 System Tours
 Project Coordination
 Site Inspections
 Property Owner Surveys

Experience

The CTS was designed to treat PFOA and PFOS, but also captures and treats the VOCs present in the groundwater. The VOCs consume dissolved oxygen and create favorable conditions for iron/magnesium reducing bacteria that cause biofouling. The biofouling increases the pressure within the vessels and backwashing is required two to three times per week to keep the system operational. The backwashing generates a significant amount of water, which must be treated prior to being discharged. Bay West developed procedures to keep some of the purge wells online while the backwash water is being treated to maintain the desired capture zones. Bay West has also developed a comprehensive well rehabilitation procedure consisting of acid cleaning and pH enhanced disinfection to address the biofouling at the purge well fields. We are also evaluating filtration technologies including green sand filters as potential additions to the treatment train to reduce the biofouling.

 

Stakeholder and Public Interaction

The CTS is becoming a focal point for the restoration activities at this former DoD facility, as PFOA and PFOS are becoming the primary chemicals of concern. Since the CTS was designed, multiple stakeholder outreach efforts have been made, including the following tours to present the CTS:
• Restoration Advisory Board Construction Tour – April 2018
• Restoration Advisory Board Construction Completion Tour – August 2018
• Congressional Tour – September 2018
• Assistant Secretary of Defense Tour – April 2019
Bay West supported these stakeholder tours by preparing the CTS to eliminate potential hazards, developing tour narratives to highlight key aspects of the CTS design and operation, and leading the tours including question and answer sessions. In addition, Bay West supports the DoD in meetings where restoration activities are discussed with the project stakeholders and regulators. The on-site staff also perform routine site inspections and property owner interviews to verify that the land use controls are in compliance.

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Dirk Pohlmann, PE, PMP

Dirk Pohlmann, PE, PMP

Senior Environmental Remediation Engineer

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Paul Raymaker, PG

Paul Raymaker, PG

Team Leader, PFAS

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