REMOVAL OF HEAVY METALS FROM STORMWATER RUNOFF BY A PASSIVE MULTI-BARRIER TREATMENT SYSTEM
FIELD EVALUATION AT GLENCORE’S BULK STORAGE FACILITY IN PORT OF TOWNSVILLE
K Athanasiadis, P McFadyen, M Brennan
Publication Date (Web): 16 May 2016
A series of white papers and articles published in peer-reviewed journals have focused on the challenge of evaluating stormwater runoff quality and the ability of commercially available stormwater runoff devices to successfully control the runoff and its pollutants. This paper summarises the results from a field trial of GHD’s StormDMT™ device treating the stormwater runoff generated at a bulk storage facility in Port of Townsville.
Stormwater runoff is one of the major environmental risks to receiving waterways that increasingly degrade as urban population densities increase. The significant impact of discharging untreated stormwater runoff is driving stricter environmental regulations in Australia and globally. At the same time, where stormwater can be captured and reused, it is also becoming valued as part of a diverse water supply portfolio, in line with the principles of Water-Sensitive Urban Design (WSUD).
Typical WSUD structures used in stormwater management are swales, bio-retention systems and constructed wetlands. These systems can achieve significant reductions to Total Suspended Solids (TSS 70–80%), Total Nitrogen (TN 40–50%) and Total Phosphorous (TP 50%). This reduction is mainly due to the removal of the particulate bound contaminants. The load reduction of NOx, PO4 3- and dissolved heavy metals is effective only in constructed wetlands, although with inconsistent performance.
In addition, these systems require significant land surface area: 1–2% of the catchment area for a bio-retention basin and 5–6 % for a constructed wetland. This is a major issue when the available land is at a premium.
To fill this gap a range of engineered stormwater quality improvement devices is available on the market from various commercial vendors. However, a protocol to allow the evaluation of the performance claims made by vendors is still not in place in Australia.
The aim of this field trial was to assess the performance of the StormDMT technology, a passive multi-barrier stormwater treatment system, against critical stormwater runoff parameters such as storm event pollutograph, runoff quality, and pollutant phase distribution (particulate, dissolved and colloidal). Flow-based stormwater quality data were obtained from six major storm events during the wet season of 2012 and 2013.
The StormDMT multi-barrier filter has demonstrated an event mean removal efficiency of approximately 87%for total copper, 80% for total lead and 76% for total zinc. Considering the site-relevant stormwater runoff pollutant rates, the StormDMT filtration unit demonstrated a minimum maintenance life of one year.
The bulk storage facility in the Port of Townsville
Click here to read the full paper