Though not typically included in the urban stormwater sector, there are opportunities for communities to achieve pollutant reductions through upgrades to residential septic systems and small wastewater treatment plants.  Residential septic systems, especially older ones, are prone to nitrogen leaks.  Upgrading the pre-treatment tank or making enhancements to the drainfield can be effective nitrogen reduction strategies.  Upgrading wastewater treatment plants is another effective nutrient reduction strategy.  While most of the larger facilities (those that serve over 5,000 people) have already been upgraded to sharply increase their nutrient capability, opportunities still exist to improve treatment processes at the smaller plants. 

The Chesapeake Stormwater Network’s On-Site Wastewater Treatment Systems Nitrogen Reduction Technology Expert Review Panel was tasked with identifying and recommending on-site wastewater treatment technologies or modifications to existing wastewater treatment systems that would reduce total nitrogen loads to the Chesapeake Bay watershed. The Panel reviewed existing scientific research and provided recommendations for reduction credits and verification of BMP performance.  Resources include the expert panel report and a webcast on wastewater and septics.