Guidance on Water Management Strategies for the Quarry Industry

ALEXIS VALENZA, Director of Valenza Engineering and JOHN NOLAN of Nolan Consulting provide a report on Water Management strategies for the Quarry Industry.

Who we are?

Alexis Valenza and John Nolan have been involved in groundwater, surface water and environmental consulting services for the mining and quarrying industry for the last 30 years, both in Australia and internationally. They both hold a Master in Hydrogeology and have a combined experience in excess of 50 years, covering quarry and mine water supplies, environmental impact assessment, quarry de-watering, water balance, environmental monitoring and expert witness services.

This article provides guidance on developing and implementing water management plans for dry (above water table) and wet quarries. The guidance is based on experience on numerous sites,
and is aligned with the current standards and best management practices adopted in Australia. In writing this article, several documents and reports have been reviewed and analysed. The
reference of the source documents is available in the footnotes.

Background

Water is an important resource for the quarrying industry, as a significant water user and producer of process water. Water can also be a problematic resource, which effect quarry operations
and the surrounding environment (footnote 1). Water is a shared natural resource which should be carefully managed to improve the growth and profitability of quarry industry businesses. Inappropriate management of water is generally underlined by inadequate water balance assessment and operational planning. As a result, work authorities, permits and licences can be based on inadequate information and as a consequence the resultant conditions have been difficult to implement in practice (VTT 2016).

Early planning of water resources through the development and implementation of a Water Management Plan (WMP) is essential for all quarries.

The relevance of each of the requirements detailed in this article will differ depending on the nature of the quarry and the existence of water features and dependent ecosystems in the surrounding environment.

A WMP supports quarries in meeting future demand, leads to better security of operations (minimising risks in preventing damage caused by extreme weather events, for example, floods,
slope failure, etc.), and drives more effective investments in capital works. Failures in water resource management throughout the whole of quarry life cycle can lead to situations where community and government support for current and future projects can be increasingly difficult to achieve. An early stage site wide approach is required to help identifying risks and opportunities related to the management of water resources. (Julien et al. 2005 – footnote 2).

Relevant Legislation and Guidelines

The main Acts that govern water related issues in quarries are the Water Act 1989 (Victoria), the Environment Protection Act 1970 (Victoria), the State Environment Protection Policy (SEPP), The
SEPP Waters of Victoria 2003 (WoV), the Water Management Act 2000 (NSW), and the Environmental Planning and Assessment Act 1979 (NSW). However, significant conditions can be imposed through Take and Use Licences, Works Approvals, Planning Approvals and Work Authorities. It is therefore essential to consider these when determining what water management (and
related risk management) measures are required at each quarry.

Energy and Earth Resources (EER) Regulation have issued in 2014 an environmental guideline for the “Management of Water in Mines and Quarries” (2014 – footnote 3). The guideline provides information for operators on how to manage discharges of wastewater from a mine (and quarry) sites to ensure compliance with Victorian legislation. It includes protection of ground and surface water quality for downstream users.

Potential water related issues

The main potential water related issues encountered on quarry sites are different for dry (above water table) and wet quarries. They are listed below:

• Rain water inflow and emergency discharge issues (mainly for dry quarries)
• Inadequate water to meet demand (dry quarries)
• Environmental impact of discharge to the surface water drainage system (temporary or permanent)
• Degradation of in pit water quality and surrounding groundwaters (wet quarries)
• Loss of supply to other users due to de-watering (wet quarries)
• Pit flooding due to bunding or slope failure (quarrying below creek bed / lake level)
• Downstream flooding due to pond bunding failure

The EER guideline states that “Water conservation is part of any sound resource management practice. Whenever possible, a mine or quarry should attempt to close the loop of water use so
that a discharge is not required.”

Examples of effective water management solutions are listed below:

• Groundwater contamination: The impact of quarrying on  aquifers in terms of potential contamination and change in groundwater flow patterns is often ignored, regardless of the amount of material quarried below the water table. Storage of fuels, lubricants, chemicals etc. must be undertaken such that there is no leakage to underlying aquifers. Water should not be discharged where quality parameters are exceeding background conditions. Where salinity of waters of the receiving environment is proven to be naturally high, compared to SEPP (footnote 4) levels, background data should be collected and the exceedances documented during planning stage to support the discharge approval process.
• Surrounding users: Use of groundwater for de-watering and or supply and surface water for supply can impact upon the available yield and quality for other beneficial uses including the environment. The assessment will aim to maximise the collection and the analyses of existing data from neighbouring properties.
• Safety, cost savings and community: Effective water management helps stabilise quarry walls and stockpiles during and after extraction. Effective de-watering prevents temporary flooding of the operation and its assets, optimising production and reducing operational costs (by reducing cost of haulage for drained material, for example). Applying correct treatment to any water discharges to meet permit requirements will help avoid costs and delays caused by interventions by regulatory authorities.

Appropriate assessment of the availability and vulnerability of the resource allows for good site-management of water and ameliorates impacts upon the surrounding community, thereby minimising costly community objections. The Water Management Strategy shall meet the quarrying and processing requirements of the project whilst minimising the environmental impacts of any water management or disposal activities (EER).

A Water Management Plan is generally required as part of the Environmental Management Plan or Work Plan for the quarries operations. The framework of the WMP is described below.

Water Management Plan objectives

The objectives of the WMP are to:

• Ensure relevant statutory and environmental conditions requirements are met;
• Meet the company internal environmental strategy  and policies;
• Employ applicable best practice water quality tools to manage and minimise the impact of quarrying operations on surrounding surface water bodies and groundwater aquifers;
• Maintain an effective response mechanism to deal with on-site and off-site issues and complaints from the surrounding community; and
• Ensure the results of the surface water and groundwater quality monitoring comply with applicable criteria (footnote 5)

WMPs address water management associated with operation of the quarry and associated infrastructure. The WMP should include at a minimum the following elements:

• Purpose of the Plan
• Quarry Staging
• Site Water Balance
• Impact Assessment
• Erosion and Sediment Control Plan (includes mitigation measures)
• Surface Water & Groundwater Management Plan
• Surface Water & Groundwater Monitoring Program
• Surface and Ground Water Contingency and Mitigation Measures Strategy.

WMPs should cover the following domains (footnote 6).

• Site water demands and sources: identifying and quantifying water demand and supply methods (both for surface water and groundwater);
• Water segregation: separation of site waters, based on quality, to maximise recycling;
• Surface water diversion: redirecting creeks or other waterways to prevent water from entering the active quarrying area;
• Surface water protection: protecting water features such as lakes, ponds and wetlands to prevent contamination;
• Release strategy: strategy for temporary or permanent release of water from the quarrying area to the environment, taking into consideration flow and water quality characteristics of the receiving environment;
• Infrastructure requirements: structure, location and capacity of water management infrastructure such as pumps, pipes and dams;
• Post-closure water management (final voids): expected lake formation, water levels and water quality within final voids.

Conclusion and Recommendations

Water management should be initiated during the early planning phases (when the initial planning is developed, testing water demand against supply conceptually, confirming water requirement stages), and continues throughout the life cycle of the quarry. The plan should be developed and updated throughout the life of the operation, including water monitoring data collection. Recent works advise to break down the site into unit domains, allowing to simulate scenarios where water management may be modified, causing a change to either flow volumes or water quality or both. Unit domains are to include plant, pits, water basins and ponds, de-watering units, overburden stockpiles, water treatment facilities, existing springs, groundwater, surface waters, ditches, and rainfall (VTT 2016).

Once the layout of the site is established and water usage decided, a monitoring programme can be developed and data acquisition initiated (including site rainfall and evaporation, groundwater bores, existing wetlands, creeks, springs or lake, and quarry discharge receptors – if any). The information compiled forms part of the permits that the quarry will submit to the statutory authorities.

As quarrying commences and operates in stages, validation of the initial WMP is achieved by collecting site monitoring data (including actual water consumption, rainfall capture volumes, discharge and treatment volumes and quality). The WMP should be continuously verified and modified as the operational needs and site conditions change, including when the quarry transitions to rehabilitation and closure stages.

It is important to realise that those stages are likely to be substantially different to the situation where quarry operations and personnel were available. Consequently, the WMP should consider that the amount of water cycling in a closed site differs drastically from the situation during operations (adapted from VTT 2016).

For example, final in-pit water level may require final bunds to be elevated compared to operating stages, spring diversion should be rehabilitated to initial stages. In some cases, where permanent water release to the surrounding environment is required, ongoing treatment may be needed and the associated monitoring conducted.

For more information, contact CMPA member Alexis Valenza on 0423 305

 

 

 

 

 

 

Footnotes

1. Guidelines for mine & quarry water management, VTT Technologies (Ref VTT Technology 266, ISBN 978-951-38-8443-7, 2016)
2. Julien, M.R., Gowan, M., Nalecki, P. & Kissiova, M. 2005. Water balance and its integration in mine operation through the use of real-world systems modelling tools. 2005 Symposium Mines and the Environment, Rouyn – Noranda, Quebec, Canada.
3. EER Environmental Guidelines: Management of Water in Mines and Quarries – Victorian Legal and Policy Requirements (Feb 2014)4
4. SEPP Waters of Victoria 2003 (WoV)
5. Adapted from BHP – Site Water Management Plan (Publically available, ref Mac-Enc-Mtp-034) and EER Environmental Guidelines: Management of  Water in Mines and Quarries – Victorian Legal and Policy Requirements (Feb 2014)
6. Adapted from XStrata – Newlands Coal Extension Project EIS, Chapter 11 (Publically available, no document reference or date)

 

 

 

 

 

 

 

 

 

 

 

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