Event Title
Bioretention for Lakes: Washington's search to replace compost in our stormwater filters
Streaming Media
Presentation Abstract
Bioretention is the most widely applicable and flexible stormwater treatment practice we have available today. The Washington State Department of Ecology (Ecology) specification for bioretention soil media (BSM) is a mixture of 60 percent sand and 40 percent compost (60/40). Washington is not alone by including compost in BSM; Massachusetts, Nebraska, Maryland, Colorado, the list goes on. While the 60/40 BSM can provide reliable water quality treatment for some contaminants, it has been shown to export high levels of nitrogen and phosphorus. We will present the journey that the state of Washington has taken over the last 6 years to find an alternative to compost in BSM. From selecting and testing individual components in the lab, to column studies, toxicological studies, and plant health assays, we developed a new BSM that is an effective nutrient filter. The final mix, High Performance BSM (HPBSM) is a combination of sand, coconut coir, biochar, iron filings, and activated alumina. We have documented median removals of 73 and 5 percent for total phosphorus and nitrate+nitrite, respectively. This contrasts with order of magnitude increases in these constituents using the 60/40 BSM. The HPBSM also reduces stormwater toxicity and can sustain a healthy plant community. Ecology recently released the HPBSM specification for use in Washington. Bioretention, once prohibited from being installed adjacent to sensitive lakes, can now be used across the state, expanding the reach of this powerful stormwater treatment tool, and protecting our lakes and streams.
Session Title
Innovations and Emerging Science 1
Conference Track
SSE1: Science for the Future
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-traditionals-393
Start Date
27-4-2022 9:45 AM
End Date
27-4-2022 11:15 AM
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Type
Text
Language
English
Bioretention for Lakes: Washington's search to replace compost in our stormwater filters
Bioretention is the most widely applicable and flexible stormwater treatment practice we have available today. The Washington State Department of Ecology (Ecology) specification for bioretention soil media (BSM) is a mixture of 60 percent sand and 40 percent compost (60/40). Washington is not alone by including compost in BSM; Massachusetts, Nebraska, Maryland, Colorado, the list goes on. While the 60/40 BSM can provide reliable water quality treatment for some contaminants, it has been shown to export high levels of nitrogen and phosphorus. We will present the journey that the state of Washington has taken over the last 6 years to find an alternative to compost in BSM. From selecting and testing individual components in the lab, to column studies, toxicological studies, and plant health assays, we developed a new BSM that is an effective nutrient filter. The final mix, High Performance BSM (HPBSM) is a combination of sand, coconut coir, biochar, iron filings, and activated alumina. We have documented median removals of 73 and 5 percent for total phosphorus and nitrate+nitrite, respectively. This contrasts with order of magnitude increases in these constituents using the 60/40 BSM. The HPBSM also reduces stormwater toxicity and can sustain a healthy plant community. Ecology recently released the HPBSM specification for use in Washington. Bioretention, once prohibited from being installed adjacent to sensitive lakes, can now be used across the state, expanding the reach of this powerful stormwater treatment tool, and protecting our lakes and streams.
