Environmental Monitoring and Assessment (2005) 101: 23–38
c© Springer 2005
EFFICIENCY OF AN INFILTRATION BASIN IN REMOVING
CONTAMINANTS FROM URBAN STORMWATER
G. F. BIRCH∗, M. S. FAZELI, and C. MATTHAI
Environmental Geology Group, School of Geosciences, The University of Sydney,
NSW, 2006, Australia
(∗author for correspondence, e-mail: gavin@es.usyd.edu.au)
(Received 19 December 2002; accepted 28 January 2004)
Abstract. The efficiency of a Stormwater Infiltration Basin (SIB) to remove contaminants from urban
stormwater was assessed in the current investigation. The SIB, installed in an urban suburb in eastern
Sydney (Australia), was monitored over seven rainfall events to assess the removal efficiency of the
remedial device for total suspended solids (TSS), nutrients (TP, TKN, Nox, TN), trace metals (Cd, Cr,
Cu, Fe, Mn, Ni, Pb, Zn), organochlorine pesticides and faecal coliforms (FC) from stormwater. The
weighted average concentration (WAC) of TSS in the stormwater effluent from the SIB was reduced by
an average of 50%, whereas the WAC of Cu, Pb and Zn were also reduced by an average 68%, 93% and
52%, respectively. However, the WAC of Cr, Fe, Mn and Ni displays either similar concentrations as
the stormwater influent (Cr and Mn), or substantially higher concentrations (Fe and Ni), due possibly
to leaching of fine-grained zeolite clay particles in the filtration bed. The mean removal efficiency of
the SIB for total phosphorus (TP) and total Kjeldahl nitrogen (TKN) was 51% and 65%, respectively.
In contrast, the average WAC of oxidisable nitrogen (nitrate and nitrite nitrogen or Nox) is about 2.5
times greater in the effluent (1.34 ± 0.69 mg L−1) than in the incoming stormwater (0.62 ± 0.25 mg
L−1). The WAC of total nitrogen (TN) was similar for stormwater at the in-flow and out-flow points.
The SIB was very efficient in removing FC from stormwater; and the WAC of almost 70 000 cfu
(100 mL)−1 at inflow was reduced to <2000 cfu (100 Ml)−1 at the outflow, representing a mean
removal efficiency of 96%. Due to the low c