New Stormwater Treatment System for the Removal of Phosphorus is Approved

After a 5-year collaborative effort between the City of Bellingham, Herrera, and the Washington State Department of Ecology (Ecology), the Phosphorus Optimized Stormwater Treatment System (POST) has obtained Ecology’s General Use Level Designation (GULD).

This designation is given to technologies that achieve Ecology’s stringent performance goals and allows agencies and owners to use POST as an affordable and open-source tool for the removal of phosphorus from stormwater run-off across Washington State. Phosphorus is a nutrient and originates from natural sources such as soil or decaying leaves and from synthetic fertilizers.  When stormwater run-off containing phosphorus enters lakes it builds up and causes low oxygen levels harming aquatic organisms and toxic algal blooms, a potential human health hazard.

The development of POST began in 2017 with Bellingham’s Park Place Stormwater Facility project. This project aimed to develop a new stormwater treatment media capable of removing a high level of total phosphorus from stormwater runoff, monitor a pilot scale facility using the new media, and reconstruct a regional stormwater treatment facility treating run-off from 168 acres of residential development before entering Lake Whatcom using the new GULD-approved technology.

Leveraging experience from developing a specification for new bioretention soil media with improved phosphorus removal capacity for Washington State, Herrera evaluated various combinations of media components to create a non-proprietary, high flow rate, stormwater treatment media with high phosphorus removal capabilities. From 2019-2021, Herrera designed and monitored a pilot scale prototype filter in the field in accordance with the Technology Assessment Protocol – Ecology (TAPE). The POST System met TAPE goals for Basic and Phosphorus removal at a design infiltration rate of 60 inches per hour. POST was awarded a GULD In February of 2022.

Herrera is proud of our role supporting the City of Bellingham in developing this innovative and cost-effective stormwater treatment technology to increase the health of lakes across Washington State. We look forward to seeing how this technology is used to improve water quality for years to come. Learn more about POST here.