Large Mining Operation Stormwater Management Planning.

GroundTruth engaged with a large international mine to develop a stormwater management plan to improve how rainfall was dealt with across the mine’s operations. GroundTruth adopted a two-phase approach.

The first phase involved GroundTruth engineers visiting the site to assess the nature and extent of the stormwater problems. The engineers also met with mine management to discuss the desired stormwater management objectives and develop a stormwater management philosophy. GroundTruth also used the initial site visit to conduct an unmanned aerial vehicle (UAV)-based photogrammetry survey to develop a desktop flow accumulation model of the site.

The stormwater management philosophy that was developed following initial discussions had a two primary principles:

1. Minimise any potential detrimental effects of stormwater runoff from the mine for the downstream receiving environment.
2. Ensure that stormwater is managed in a way that does not hinder the operations at the mine.

With the philosophy to guide design, the flow accumulation model was used to determine the optimal location for stormwater interventions, including shallow or wide open drains, confined open drains, culverts, and chutes, all aimed at managing the quality and quantity of stormwater runoff from the site.

The second phase focused on the design of the stormwater management interventions. The stormwater management plan included:

• Detailed hydrological and hydraulic modelling to inform the designs;
• Detailed designs of the proposed stormwater management interventions; and
• Maintenance recommendations.

Hydrological modelling informed the designs of the stormwater management interventions, with models designed to ensure that the interventions would be appropriate for managing estimated stormflows.

From a water quality perspective, the site visit highlighted that stormwater runoff from the mine was contaminated with suspended sediment. Therefore, the plans to address water quality concerns focussed primarily on the separation of clean and contaminated water and sediment control.

Ultimately, GroundTruth provided comprehensive designs and recommendations for stormwater management interventions, informed by detailed hydraulic and hydrological models of the entire site and the stormwater management philosophy. The interventions included distinct plans according to relevant zones, as well as per intervention type, including detailed designs for the placement, dimensions, and maintenance of surface drains, culverts, sediment trapping facilities, energy dissipators, new road developments, trash grids, pipes, and embankments. The proposed interventions incorporated the stormwater management philosophy, ensuring that they were efficient, sustainable, environmentally conscious, resilient, and suited the specific considerations and requirements of the mine.