Arlington County launches modernization of water pollution control plant

Arlington County Government has begun the first phase of Arlington Re-Gen, a multi-year modernization project for its Water Pollution Control Plant aimed at improving biosolids management and reducing the facility’s carbon footprint.

The project’s “Early Work Package,” launched this month, includes grading, building demolitions, utility relocation and foundation work for future treatment systems. Work will occur within the plant’s fenced boundaries and will not interrupt wastewater treatment operations.

The main construction phase is expected to begin in late 2026 and continue through spring 2031. Plans call for new solids-handling infrastructure, including thermal hydrolysis and anaerobic digestion systems designed to convert biosolids into renewable resources. The project will also incorporate modern dewatering and screening equipment, improved truck loading and advanced odor control systems.

Once complete, the upgraded facility will be able to produce Class A biosolids and renewable natural gas. Arlington’s plant treated about 21 million gallons of wastewater per day in fiscal year 2025, with nearly 20% of the flow coming from neighboring communities including Alexandria, Fairfax County and Falls Church. Treated water is discharged to Four Mile Run and eventually the Potomac River before reaching the Chesapeake Bay.