Stormwater is rainwater and anything the rain carries along with it. Once it is contaminated, it needs to be treated. Stormwater becomes polluted when it carries grease, oil, heavy metals and sediments from storage and processing areas into stormwater drains that feeds into rivers and lakes. As such, stormwater runoff is regulated by councils and EPA. Businesses are required to take steps to control stormwater contamination and stay compliant. Some of these steps are considered best management practices including wastewater treatment processes.
Industrial sites need effective management of stormwater run-off. Stormwater run-off could happen from roofs, pavements, external process or storage areas following a rain event, when contaminants get flushed from the site and into the ground. There are various types of stormwater pollution including chemical pollution and sediment pollution. Contaminants could include acids, alkalis, detergents, disinfectants, oils, dyes, engine coolants, lubricants, metals, solvents, degradable organic residues, and fertilisers.
The stormwater system includes road gutter, street drains and pipes that collect rainwater and carry it to the nearest creek, river, or sea. Litter, sediment and chemicals can wash off from process plants, especially if they have raw products or materials stored outdoors, or from building sites, that has a high amount of dust and sediment. The pollutants in stormwater can kill aquatic plants and animals. The waste can also block drains causing flooding or expensive repairs for the councils.
Risks can extend to major disasters involving harm to people. A small but consistent chemical discharge over a period of time can lead to a contamination in an aquifier. Persistent contaminants washed via drains into waterways can also cause algal blooms, sedimentation and other damage.
Whether you are in light, general or heavy industrial site, stormwater management practices must be implemented in accordance to relevant guidelines. There are some factors that need to be monitored:
- Uncontaminated stormwater runoff from roofs, paths and the site itself should not be allowed to mix with process effluent, stored chemicals or chemical spills. Whenever possible, process areas should be covered.
- Rainwater should not be released from chemical containment areas until treated, or tested and found to be uncontaminated.
- For possibility of contamination or to contain spills, containment bunds or diversion banks can be installed.
- Business needs to ensure that stormwater is not directed towards areas that hold raw stockpiles or earthworks. Areas like these are vulnerable to erosion.
- If chemical solvents and non-degradable detergents are used to clean equipment or pavements, the water should not be released into stormwater systems. The chemicals can cause environmental harm if they enter groundwater, wetlands, waterways or marine environments.
- If there are areas where stormwater may get contaminated, the water must be directed to treatment process for removal of solids, chemicals, oil and grease, or any other contaminants.
Stormwater treatment needs to be customised according to the needs of the industrial site. There are several types of treatment options
- For suspended soil particles and turbidity in water, sedimentation basins could be used or chemical coagulation, followed by settling the sediment or using membrane filters for treatment
- For oil, grease and fuel removal, petrol and oil traps, plate separators, chemical coagulation or dissolved air flotation units could be used
- For reducing litter, simple bucket traps or bar screens can prevent them from entering the stormwater drains.
Stormwater Management for Wash Bays and Wash Down Areas
Enviro Concepts is a leading manufacturer of above ground, modular wash bays. We provide a simple solution for wash bay compliance. Our Rain Diversion Systems provide an efficient way for diverting contaminated water from commercial or industrial wash bays, away from the stormwater drains. Similarly, they divert clean rain water away from sewage or filtration devices.
If you have questions on managing or treating stormwater, contact us for a free consultation.