Purpose

The purpose of this project is to evaluate the effectiveness of bioretention cells (filters made of soils, gravels, and plants) to reduce loads of organic contaminants and bacterial pathogens in stormwater.  Typical bioretention systems (e.g., raingardens) have demonstrated variable removal of such pollutants. Recent studies suggest that amendment with fungi and /or biochar may improve removal and breakdown of these contaminants. This study will evaluate these amendments as potential BMP recommendations for organic contaminant and bacterial pathogen removal from stormwater.

Scope

For one year (fall of 2019-2020), stormwater will be collected during targeted storm events and applied to a series of experimental bioretention cells. The stormwater flowing into and out of the cells will be collected and analyzed for organic contaminants and pathogenic bacteria. Soil samples will be taken from the cells periodically to evaluate the fate and transport of organic contaminants in bioretention cells.

Project Summary

Organic contaminants and bacterial pathogens are common stormwater pollutants which contribute to degradation of aquatic ecosystems, recreational water use, and fisheries production. These pollutants are not currently regulated in the stormwater permitting process because more information is needed on how to efficiently remove these pollutants from stormwater. In this study we will evaluate the capacity of typical bioretention soils, and potentially beneficial amendments (biochar and fungi), to remove these targets pollutants from stormwater.

Timeframe/timeline

2 years starting in fall 2018

Parameters measured

• Organic contaminants in water and soil

• Bacterial pathogens in water

• Soil moisture and temperature in bioretention cells

• Conventional water quality parameters (pH, DOC, TSS)

Elements Included in this Project

Three bioretention designs will be evaluated:

• Typical bioretention soil media (BSM: compost+ sand+ plants+ gravel drainage)

• BSM + fungi

• BSM + biochar

• BSM + fungi +biochar