The term passive treatment refers to treatment technologies that can function with little or no operation or maintenance over long periods of time.  Of course, all systems will eventually require some O&M, but passive systems can function for weeks to years, even decades, with little interference from humans.  The current standard is to design systems to operate for 25 year with no major O&M.  The opposite of passive treatment is active treatment, which requires regular maintenance and/or additional of treatment chemicals.  As you would expect, active treatment is often prohibitively expensive. Examples of passive treatment system components include:

Click on each component to view published papers for more information.

Click HERE to view a current list of our passive treatment projects. Click the VIEW MAP button to see the location of the system.

Below is our interactive map below which shows locations of our treatment systems in Western Pennsylvania. Click on each placeholder to see information about each system.














View HEDIN ENVIRONMENTAL TREATMENT SYSTEMS in a larger map with legends.