Water conservation and demand management [Video]

South Africa is currently facing a water crisis and we are seeing a decreasing trend in rainfall. Water quality is also under stress with increased urbanisation and associated return flows. This places a strain on the existing scarce water resources. The mining sector is a significant user of water and contributes to the pollution load through effluent discharge and diffuse sources. Mining companies will therefore need to demonstrate the efficient and responsible use and management of water. Mining companies are set to become more aware of conserving and managing water through the Water Conservation (WC)/Water Demand Management (WDM) plans for the mining sector.

Global ground engineering and environmental solutions adviser, Golder Associates, is in the process of an extensive three year project initiated by the Department of Water and Sanitation (DWS) and the Chamber of Mines, with the aim of helping to conserve South Africa’s scarce water resources and reducing the use of water by the country’s mines. Golder is assisting the DWS with the methodology and implementation plan for WC/WDM to ensure companies that use water efficiently are rewarded.

Nivi Juggath, environmental specialist and risk analyst for Golder, says the aim is to use water optimally, efficiently and effectively in the mining sector – a vital cog in the economy.

“We need to pre-empt a water crisis and plan for it. We see this as a proactive move for companies. Not only will mining companies be able to use less water and use it more effectively, but they will also enable more water to be shared among other users,” said Juggath.

Water conservation involves the minimisation of water loss, the care and protection of the water resources and the efficient and effective use of water. Water demand implies the water usage for a mine. The WC/WDM concept is therefore the implementation of a strategy or a programme by a water consumer (industry) to influence the water demand in order to meet economic efficiency, social development and equity and environmental protection and sustainability.

The three-year project involves developing benchmarks for WC/WDM in the mining sector, guidelines for WDM plans for the mining sector, and WC/WDM regulations for mining companies.

Through these initiatives, the Department will have a better understanding of water use in the mining sector. This is in line with the department’s Integrated Water Resources Management (IWRM) strategy aimed at fair and equitable use of water resources.

Juggath said each mine would be required to develop a WC and WDM plan, in line with the guidelines being developed. Water use efficiency targets will be assessed to understand the status of water management at the different sites. Mines that have good WC/WDM plans and can show that they have developed and achieved Water Use Efficiency targets will benefit through preferential access to scarce water resources.

“Mines will need to understand the water use in their plans, where they are losing water, and then define efficiency targets,” said Juggath.

She said benchmarks would be based on national and international guidelines, and the mining sector would need to meet these benchmarks.

“In a very broad sense, it starts with understanding your water management on site and having a water balance, and it ends with implementing solutions that result in cost savings and efficient water use,” said Juggath.

Watch an interview with Juggath here:

Critical to the WC and WDM plan will be the development of a detailed computerized water balance to simulate management options for water efficiency initiatives and determine actual water use efficiency status.

A water balance is used to understand and accurately portray a site’s water demand and usage. By executing a simple mass balance for each facility, as well as for the entire site, increased confidence in these numbers are obtained. These conventional water balances have been used for a number of years and have been recognised as ‘best-practice’ by the then Department of Water Affairs and Forestry, since 2006.

In a fresh move, water balances are now being used not only as a reporting tool, but as a water management and planning tool as well. The water balance model of a mine (or industrial site) is continuously calibrated and validated with actual monitoring data and where there is insufficient data the model simulates water transfers by checking the mass balances in association with the site operational rules.

“A mine will have a better real-time picture of the entire system – for example, you’ll be able to see if dams are running low and understand how long you can expect to operate if you were badly affected by a drought,” said Amelia Basson, water resources engineer for Golder.

Basson said information such as mine plans, water infrastructure design specifications and system operating rules are used to construct these simulation models which ultimately give companies a far clearer picture of how water is moved through the system.

Once the model has been constructed within a simulation environment, it becomes possible to generate representative water balances under various potential future conditions. Prior to implementing any changes, the proposed changes can be made within the model and the response of the system analysed to determine if the changes might generate more or less excess water on site or even what the probabilities of on-site flooding or shortages are.

She said the models would also enable mine management to look at areas where it could improve its efficiencies and track its usage, thus tying directly into the WC/WDM requirements.

Basson considers working on these projects as very rewarding.

“Our aim is to have a beneficial impact on the environment and natural resources that are under threat by assisting our clients to use water more efficiently and reduce the consumption of natural resources. Even a small amount of water saved could potentially have a big impact on downstream users and the lives it sustains.”

Watch an interview with Basson here:

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