Comparison of stormwater biofiltration systems in Southeast Australia and Southern California

Abstract

Stormwater biofilters (also called rain gardens, bioretention systems, and bioswales) are used to manage stormwater runoff in urbanized environments. Some benefits of biofilters include flood prevention, stormwater runoff water quality improvement, and wildlife habitat. This technology has been implemented on a larger scale in southeast Australia, but cities and counties in southern California just beginning to construct biofilter systems to manage stormwater runoff. Biofilters tend to be larger in southern California than in southeast Australia. Differences in rainfall patterns likely affect biofilter function. Southern California has much longer periods between rain events than southeast Australia, providing challenges to establishing and maintaining vegetation in biofilters. The use of biofilters for restoring predevelopment flow regimes has been studied in a peri-urban watershed in southeast Australia, but flow regime restoration is not likely in highly urbanized locations in both Australia and southern California. However, stormwater runoff treatment and harvesting in decentralized biofilters could substantially reduce storm flows and improve water quality in receiving waters while improving urban water supply and extending the life of existing stormwater management infrastructure.

Predictive Power of Clean Bed Filtration Theory for Fecal Indicator Bacteria Removal in Stormwater Biofilters

“…The FIB removal achieved at this optimal infiltration rate is strongly dependent on the catchment ratio, defined as the ratio of biofilter area to catchment area (CR = A/A c , Table S3). 44 The system with the lowest CR (Elmer Avenue) exhibits near complete FIB breakthrough across the full range of infiltration rates evaluated. In this case, the biofilter receives too much runoff (from too large a catchment area) and as a result most of the stormwater generated by the catchment bypasses the biofilter and flows directly to the storm drain (or, in the case of Elmer Avenue, other LID features including porous pavement, bioswales, or an underground infiltration gallery 68 ).…”

“…Prior to the FIB challenge experiments, all columns (both vegetated and unplanted controls) were periodically watered with synthetic stormwater (defined above) with an ADP varying from 0 to 14 days, a typical range for the Melbourne area. 44 Here we focus on a subset of CH's FIB challenge experiments (n = 196) for which the reported infiltration rate was greater than 7.0 × 10 −6 m s −1 ; this threshold represents the lower bound of infiltration rates for which our CBFT correlations apply (see later), and is at the low end of recommended hydraulic conductivities for biofilters in temperate and tropical environments. 45 2015/2016 Follow-Up Experiment.…”

Water Recycling via Aquifers for Sustainable Urban Water Quality Management: Current Status, Challenges and Opportunities

“…Roof runoff is diverted into a well, sump or caisson (e.g., geofabric lined trench) filled with sand or gravel and allowed to percolate to the water table where it is collected by pumping from a well. A variation is a raingarden or bioretention/biofiltration system in an urban context, involving vegetation planted within a filter media to improve water quality Below ground storage avoids evaporative losses, lessens surface footprint, which is advantageous in urban areas with high costs of land, and lessens clogging due to algal photosynthesis Reduces surface runoff and increases groundwater recharge Infiltration coupled with RWH can help modify urban microclimate and thus mitigate the heat island effect [52] RWHR in Tel-Aviv, Israel [51] Biofilters and rainwater harvesting in Melbourne, Australia and California [53] 2. Scientific Challenges…”

From Rain Tanks to Catchments: Use of Low-Impact Development To Address Hydrologic Symptoms of the Urban Stream Syndrome

“…113 Climate change also has implications for the "green" component of many LID systems. 112,114 In the end, both challenges (uncertain maintenance and uncertain climate) are probably best addressed by using uncertainty quantification where possible (e.g., with DREAM and AMALGAM, see above), factoring in redundancy, and designing smart (perhaps modular) LID systems that can readily adapt to a changing world. 113,115 Practical Constraints.…”