Are you considering re-using stormwater - our CHASM tool may be of use

April 30, 2018

Seqwater and property developer Stockland used our CHASM tool to assist in identifying potential hazards of harvesting stormwater at the Sunshine Coast.

Seqwater is working with Stockland, one of Australia’s largest property development companies, to investigate the feasibility of harvesting stormwater from its $5 bn Aura business and residential development at Caloundra. The harvested water would be pumped into the nearby Ewen Maddock Dam, which is used for drinking water supply. As part of the feasibility investigation potential water quality hazards that may be present in the harvested stormwater are being investigated.

A comprehensive list of water quality hazards that may be associated with stormwater reuse was developed, drawing from relevant guidelines and standards such as the Australian Drinking Water Guidelines, Queensland’s standards for purified recycled water and water quality objectives from Queensland’s Environmental Protection Policy for Water. The Chemical Hazard Assessment of Stormwater Micropollutants (CHASM) tool was used to assist in identifying the hazards that may be present in the Aura stormwater, based on historic and planned land uses for the development. The identified hazards were combined with a literature review undertaken by University of the Sunshine Coast and the use of the USEPA PBT profiler tool  to identify compounds that may present long-term risks to people or the environment, including Persistent, Bioacumulative and Toxic (PBT) compounds. These activities narrowed the initial list of hazards from 527 to 80.

Three of the 80 compounds were found to be PBT in nature and were passed directly through for monitoring and fate assessment. The maximum concentrations of the remaining 77 compounds reported by CHASM or the literature review were identified and compared to guideline or standard values. Any compound that had a maximum detection greater than the guideline/standard was prioritised for monitoring and fate assessment. A further seven compounds were identified as having a maximum detection that was greater than 10% of the guideline or standard. These compounds were assessed based on consideration of the historic and planned land uses and activities within the site and the professional judgment of water quality specialists.  Three of these seven compounds were then included for further analysis. The final list of compounds requiring further consideration was also reviewed to identify any gaps in indicators for chemical groups, with additional indicator compounds identified by CHASM, for example acesulfame K as an indicator of sewage, included in the final list, resulting in a total of 34 compounds.

The CHASM tool assisted Seqwater and Stockland to prioritise the water quality hazards during the feasibility phase of harvesting stormwater from Aura for augmentation of drinking water supply. CHASM saved significant time, effort and money in identifying chemicals associated with land-uses within the development and enabled an optimised monitoring program to be undertaken. See Tony McAlister’s presentation on Thursday 10 May at Ozwater to learn more.  The tool is available here.