Controlling water flow from an abandoned mine to a nearby river

The situation

When water fills our customer’s abandoned asset, it’s pumped to a nearby river.

However, the water within the asset contains potentially harmful deposits and high salinity levels, so it can only be discharged into the river when the river is deep enough to dilute it.

The water levels in the asset must also be carefully controlled to prevent water from escaping into unknown, unmonitored, and underground channels and polluting watercourses.

Through the data we routinely collect for our customer, we noticed that the pumping stations in the area – whose job was to control the water levels in the asset – were allowing the water to get too high, too often, posing an environmental risk.

We were tasked with designing and installing a solution to control water flow from the asset into the river more efficiently using automation. This project was essentially a pump test, the first stage in evaluating a new pumping station or treatment scheme.

Our approach

The first thing we did was build a small pumping station on site. This would allow us to understand better what was happening within the asset.

A large steel headworks structure was erected to support two new pumps. The first was a 150-litre per-second pump weighing a tonne, installed 100 metres below ground level, and the second was a 50-litre per-second pump weighing three-quarters of a tonne, installed 110 metres below ground level.

The headworks installed to support the pumps with conductivity monitoring

New pipework was installed from the asset alongside a railway line discharging into the river. However, two critical factors – the river level and the water’s salinity –had to be considered to determine the pump flow rates.

Therefore, we fitted a conductivity sensor to monitor salinity levels at the headworks. At the discharge point, we installed a sensor to monitor river levels and a camera to photograph the river three times a day to capture its condition.

Data is fed to a control panel at the headworks via modems over a mobile network. A unit within the control panel then automatically alters the rate at which the pumps discharge the water out of the asset and into the river based on river levels and salinity, avoiding polluting nearby watercourses.

The new pump control panel

Obstacles we overcame

  • River levels
    One effect of climate change is new rainfall patterns. The pumps have to speed up and slow down based on river levels. When the river is high, we can pump more water from the asset into the river to dilute the pollutants. When it’s low, we have to pump less. The automation we designed and installed considers this and eliminates this obstacle.
  • Lack of power
    The point where we water from the asset into the river is more than half a mile from the pumping station, and it lacks power. To overcome this, we installed a solar panel system to charge the batteries of the sensors and cameras that monitor river flow levels and conditions.

Our impact

As a result of our work: