Passive treatment utilizes gravity, natural materials, and natural chemical and biological processes to remediate water polluted with acidity and metals. Passive systems typically contain several treatment units which include limestone beds, constructed wetlands, and ponds containing limestone and/or organic substrates. Properly designed and constructed passive systems reliably treat mine water to conditions that satisfy effluent permits and provide stream restoration benefits. Compared to chemical alternatives, passive systems have less operation and maintenance requirements and the total long-term treatment costs are typically 50-75% lower. Passive systems commonly generate ecological and wildlife benefits and some systems produce clean metal solids that can be recovered and sold. Twenty-five years ago Robert Hedin and his colleagues developed passive system design criteria that are still widely utilized. Since 1994, Hedin Environmental has designed 50 installed passive treatment systems.
Learn more by viewing a current list with links to location maps.
Below is our interactive map which shows locations of our treatment systems in Pennsylvania. Click on each placeholder to see information about each system.