Type of Presentation

Oral

Session Title

Bioretention Performance in the Pacific Northwest

Description

The current municipal Nation Pollutant Discharge Elimination System stormwater permit for Washington State requires the use of low impact development (LID) practices as the first option for managing stormwater where feasible. Bioretention is the most widely applicable and flexible BMP in the suite of LID practices. While bioretention can provide very good water quality treatment for many contaminants, regional and national research indicates nitrogen (N), phosphorus (P), and copper (Cu) may be exported from these systems.

This presentation will describe a study focused on optimizing bioretention soil media for improve retention of N, P, and Cu. The analyses and media design consists of three phases:

  • Leaching analysis: Synthetic Precipitation Leaching Protocol was performed on individual media components to determine P, N, and Cu export potential. These data and other performance measures were considered to select individual media components for media blends.

  • Flushing media blends: The best performing individual components were used to develop media blends and those blends placed in 20 cm laboratory columns with under-drains. The media columns were flushed with deionized water and the effluent assessed for total dissolved solids, dissolved organic carbon, hardness, total and dissolved metals, nitrogen, phosphorus, and other parameters.

  • Dosing media blends: stormwater with targeted concentrations of contaminants was applied at specified rates and loads to determine the pollutant capture capability of the media blends. The above suite of parameters were also analyzed for the dosing phase.

Eight media blends (treatments) were selected. Each treatment was replicated three times and a 45.7 cm layer of the media placed above a 30.5 cm drainage layer in the columns. Media blends consisted of a compost-based media control and treatments consisting of various ratios of volcanic sand, iron-fused wood chips, diatomaceous earth, coco coir-peat, and high carbon fly ash, activated alumina, and granular activate carbon.

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Analysis of Bioretention Soil Media for Improved Nitrogen, Phosphorus, and Copper Retention

2016SSEC

The current municipal Nation Pollutant Discharge Elimination System stormwater permit for Washington State requires the use of low impact development (LID) practices as the first option for managing stormwater where feasible. Bioretention is the most widely applicable and flexible BMP in the suite of LID practices. While bioretention can provide very good water quality treatment for many contaminants, regional and national research indicates nitrogen (N), phosphorus (P), and copper (Cu) may be exported from these systems.

This presentation will describe a study focused on optimizing bioretention soil media for improve retention of N, P, and Cu. The analyses and media design consists of three phases:

  • Leaching analysis: Synthetic Precipitation Leaching Protocol was performed on individual media components to determine P, N, and Cu export potential. These data and other performance measures were considered to select individual media components for media blends.

  • Flushing media blends: The best performing individual components were used to develop media blends and those blends placed in 20 cm laboratory columns with under-drains. The media columns were flushed with deionized water and the effluent assessed for total dissolved solids, dissolved organic carbon, hardness, total and dissolved metals, nitrogen, phosphorus, and other parameters.

  • Dosing media blends: stormwater with targeted concentrations of contaminants was applied at specified rates and loads to determine the pollutant capture capability of the media blends. The above suite of parameters were also analyzed for the dosing phase.

Eight media blends (treatments) were selected. Each treatment was replicated three times and a 45.7 cm layer of the media placed above a 30.5 cm drainage layer in the columns. Media blends consisted of a compost-based media control and treatments consisting of various ratios of volcanic sand, iron-fused wood chips, diatomaceous earth, coco coir-peat, and high carbon fly ash, activated alumina, and granular activate carbon.