The Hood Canal Onsite Septic System Nitrogen Reduction Project, which works to remove nitrogen from the effluent in a septic system, began in early 2014. The nitrogen reduction system was developed and tested by the Washington State Department of Health and University of Washington. With funding from the Department of Health, HCSEG installed two systems on nearshore properties along the lower Hood Canal.
Samples are taken once a month at the two properties from multiple points within the septic systems. Studying these samples will assess the overall performance of the systems and their components. The components include a recirculating gravel filter and a denitrifying woodchip bed filter, which are placed between the septic tank and the drain field. These systems can retrofit any existing septic system where the components will fit.
For the first part of 2015, monitoring results found that while the system’s performance was negatively impacted by cold weather, the experimental components started to recover. More specifically, the portion of the system known as the vegetated denitrifying woodchip bed made the rebound from the lower levels of performance observed in the winter. The recirculating gravel filter, on the other hand, never seemed to show a lack of performance in response to the cold temperatures, which is great news. Overall, the systems typically maintained over 50% nitrogen reduction, even during the colder months. As monitoring continues through the summer and another winter, we will start to get a better idea of how the systems perform through the seasons.
The systems will continue to be monitored through May of 2016, after which a final report will be completed. The final report will address maintenance, cost, performance and aesthetics. Ultimately, the report will provide insight to whether the widespread implementation of this technology is feasible.
If you’d like to learn more, contact Julian Sammons by email or (360) 275-3575 ext. 15.