Urban

Keeping the soil on site: Improving sediment and erosion control on construction sites.

Impacts of erosion on construction sites

South East Queensland (SEQ) urban areas are expanding rapidly to keep pace with population growth. With increased development comes increased land clearing and earth disturbance, resulting in exposed soil which is susceptible to erosion. Wind and rain erode exposed soil creating either dust which pollutes air, or dirty water run-off which pollutes waterways and aquatic environments.

Development and construction sites that do not implement measures to reduce erosion can lose 200-400 tonnes of sediment per hectare per year. Under current SEQ development rates, this equates to approximately 500,000 tonnes of sediment per year entering SEQ waterways – the equivalent of 50,000 dump trucks.

If erosion is prevented and sediment is captured on construction sites through the implementation of erosion and sediment control (ESC) measures, it is estimated that sediment loads could potentially be reduced by 85-95%. This would effectively remove approximately 425,000-475,000 tonnes of sediment pollution per year, resulting in multiple benefits for the environment, community, local governments and industry.

Sediment pollution impacts

Sediment pollution is one of the most significant threats to the health of SEQ’s waterways.

Sediment can impact on waterways in many ways, including:

• Reducing water clarity and light availability.
• Smothering benthic organisms such as plants and corals.
• Damaging fauna habitat and health.
• Reducing amenity and recreational use.
• Blocking stormwater drains and reducing waterway capacity, which increases flood risk and impact.
• Affecting water resource supply, quality, and infrastructure.

This has consequences for the overall value of SEQ’s waterways, which are estimated to contribute over $10 billion per year to the region’s economy through tourism, recreation, fishing, and drinking water supply.

Preventing sediment run-off from construction sites using erosion and sediment controls

To reduce sediment run-off during the construction phase of urban development, ESC measures should be implemented.

ESC measures reduce sediment pollution and keep soil on site by:

• Reducing the amount of water running over the site by installing drainage controls.
• Reducing the amount of soil exposed by applying erosion controls such as soil binders and vegetation.
• Capturing sediment before it runs off the site by installing controls such as sediment basins and sediment fences.

It is a requirement under state legislation for all construction sites to implement best practice ESC measures.

Implementing erosion and sediment controls can also provide direct benefits to developers and builders by reducing:

• The amount of soil lost from construction sites.
• Damage to infrastructure caused by sediment clogging drains and roads.
• Damage to infrastructure caused by undermining.
• Amount of reprofiling and re-work required on site after rain events.

Supporting government and industry to improve ESC practices

Healthy Land & Water, through its Water by Design Program, has facilitated an ESC Community of Practice over the last ten years. The ESC Community of Practice has brought together government and industry stakeholders in SEQ to collaborate and share information and practices, resulting in improved consistency of ESC regulation across the region.

Over this time, the Water by Design program also delivered a suite of capacity building activities for government and industry throughout Queensland including:

• ESC training and workshops.
• ESC field days.
• ESC compliance officer swaps.
• ESC decision support tools.
• ESC educational materials, including factsheets, videos and decision support tools hosted on the Water by Design website.

These activities have helped to improve government and industry knowledge of ESC which has contributed to the overall improvement of ESC regulation and practices.

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