Design aspects and plant species affect pollutant removal in Southern California stormwater biofilters

Abstract

We conducted a column study to better understand the relative effects of plants, design elements, and operating conditions on pollutant removal in stormwater biofilters in southern California under local conditions. We planted five southern California native species (Baccharis pilularis, Carex praegracilis, Juncus patens, Leymus condensatus, and Muhlenbergia rigens) in experimental biofilter columns fitted with a saturated zone and evaluated pollutant removal during weekly dosing and following a 52-day dry period. Columns planted with C. praegracilis and J. patens were also evaluated under conditions of fortnightly dosing and without the presence of a saturated zone. During weekly dosing, planted columns had a total nitrogen removal efficiency of 46% on average whereas removal was 8% in unplanted. B. pilularis and M. rigens performed better than other species at nitrogen removal. The presence of a saturated zone improved nitrogen removal and metal removal, but only before the 52-day dry period. With a few exceptions, local best management practice effluent concentrations limits were exceeded but performed similarly to existing southern California biofilters. Nitrogen removal decreased slightly under a fortnightly dosing frequency, which better represented rainfall event frequency in Los Angeles when compared to weekly dosing.

Adaptive strategy biases in engineered ecosystems: Implications for plant community dynamics and the provisioning of ecosystem services to people

“…Of the ecological components of GSI, plants are perhaps the best studied. Indeed, efforts to characterize the survival of different plant species in GSI as well as their relative capacity to perform desirable functions (Lundholm et al, 2010, 2015; Payne et al, 2014, 2018; Read et al, 2008; Rippy et al, 2021; Winfrey et al, 2020) have led to a proliferation of plant lists in design manuals used by practicing engineers and landscape architects that are beginning to include information about plant‐specific tolerances of common GSI stressors (e.g. transient inundation, deicers; LID SC, 2014; Michigan LID, 2008; NC DEQ, 2018; PA BMP, 2006) and their capacity to provide ecosystem services (e.g.…”