White Rock Quarry (Hanson)
The Department for Energy and Mining (DEM) is the lead regulator of the White Rock Quarry.
Hanson Construction Materials Pty Ltd (Hanson) must achieve the compliance objectives and criteria of the mine operations plan (MOP), which is regulated by DEM.
Additionally, Hanson holds an EPA licence (No. 12714) with conditions to manage surface water and stormwater. The licence also contains an environment improvement program (EIP) requiring Hanson to undertake a range of short, medium and long term actions to improve stormwater quality and reduce sediment discharge off-site. Hanson must comply with the licence conditions and the Environment Protection (Water Quality) Policy 2015 (Water Quality Policy).
On 24 September 2021 the EPA issued a formal warning to Hanson due to non-compliance with EPA licence conditions and the EIP. Hanson is required to undertake a range of actions to improve its surface water management and take all reasonable and practicable measures to meet the water quality specified in the Water Quality Policy.
Surface water management
While there are a number of sources of sediment to Third Creek, DEM and the EPA are responsible for regulating sediment discharges from sources such as the White Rock Quarry. There are specific surface water criteria outlined within the mining operations plan (MOP) which Hanson is required to comply with.
The environment improvement program (EIP) in the EPA licence that requires Hanson to undertake a range of short-, medium-, and long-term actions to improve stormwater quality and reduce sediment discharge off site.
The EIP was developed in 2017 in line with the Water Quality Policy. A water quality monitoring program stipulated in the licence requires Hanson to engage independent consultants to conduct continuous water quality monitoring at the site. This data must be reported to the EPA on a quarterly and annual basis and the results inform the effectiveness of existing and recently implemented management measures.
Operations at the quarry must be in compliance and the EPA works with DEM to inform regulatory actions when standards are exceeded.
The topography of the site is complex and surface water management is challenging. Sediment control is likely to be an ongoing improvement for Hanson. The EPA and DEM are committed to ensuring Hanson takes all reasonable and practicable measures to reduce its off-site discharge and impact.
Winter 2021 rainfall and the impact on Third Creek
Rainfall in June and July 2021 was higher than average. This resulted in all creeks flowing faster, especially in the Hills region, and caused a normal increase in turbidity of the creeks, which means they change colour due to surface erosion from a number of sources.
Stormwater pollution from multiple sources also affects the creeks and has a collective impact on receiving waters.
Highly turbid (coloured) water entered Third Creek from both the White Rock Quarry and sources such as public roads.
Action required over the next 12 months
The EPA has been engaging with Hanson regarding surface water management during high rainfall events at White Rock Quarry for more than 10 years. Significant improvement has been made by Hanson under the EIP, including diversion of conservation park clean flows, site drainage and sediment capture structures, and construction of Sediment Basin 1 to treat stormwater. Further management actions include rebuilding Sediment Basin 2, a full review of the EIP action plan and water quality monitoring plan, and developing a water quality trigger, action and response plan (TARP) have been required. Hanson is in the process of implementing these actions.
Sediment control is an important part of protecting the aquatic environment. The EPA and DEM will continue to monitor the effectiveness of any new management measures and will continue to require further improvement until the objectives of the MOP and EPA licence are achieved.
The EPA and DEM have also been actively engaging the Department for Environment and Water (DEW) and the Hills & Fleurieu Landscape Board, who are responsible for overseeing the operator’s rebuild of Sediment Basin 2 with respect to maintaining water flows.
Sediment discharges and the proposed expansion
While Hanson is working toward bringing the current operation into compliance through significant investment on the sediment control measures, the EPA is assessing and providing advice on the proposed expansion, which DEM is responsible for assessing in accordance with the Mining Act 1971, to ensure any proposed changes to operations will allow further improvements to surface water quality