Managing contaminated water on-site
- Kelly Bryant
- Jan 6
- 4 min read
Dealing with contaminated water onsite is common in construction, whether it’s high alkaline waste, wash water, silt or sludge, or hydrodemolition waste, ensuring you have a Water Management plan in place is essential.
When dealing with contaminated water, discharge into water courses or the ground (indirectly leads to groundwater) can cause a variety of both short and long-term damages, we explore these below:
Effects of suspended solids being pumped into a river
The coverage of a riverbed by silt changes substrates, leading fish gills and filter feeders to become blocked. Furthermore, the penetration of light is reduced which causes a reduction in aquatic plants ability to photosynthesize, stunting their growth.
Effects of high alkaline runoff into a water course (e.g. concrete wash water)
The increase in pH caused by a high alkalinity can cause direct harm to the gills and skin of fish and other aquatic life, impairing their ability to regulate salt and water intake as well as their ability to absorb oxygen which can lead to mass deaths, as well as reduced reproduction and growth rates.
At elevated pH levels, the less toxic ammonium ion shifts to the highly toxic, unionized ammonia form. This greatly increases the risk of ammonia poisoning, which is lethal to many fish species such as salmon.
Increased pH levels from alkaline runoff can also promote excessive growth of algae. When these die and decompose, the process depletes dissolved oxygen levels which creates hypoxic conditions (Dissolved oxygen levels too low to support aquatic life).
Common types of water contaminants in construction are high alkaline (high pH) waste or wash water, and silt or sludge.
Here are steps you can take and precautions you can implement to greatly reduce risk of spillage or il
legal discharge compromising your compliance:
Containment
Planning your containment is key to successfully keeping compliant, and identifying potential sources is an important step. Concrete washout, sediment runoff, slurry and silt all are (or have the potential to be) contaminants so their sources need to be kept in mind. Volume and composition must be considered when planning containment locations as well as proximity to the source and flow paths should be mapped out to avoid contamination of drains, watercourses, and soil.
In terms of physical containment, your primary containment should be a designated tank, bunded area, or sediment barriers for run-off to protect exposed soil. Secondary containment like trays or sumps are also important as they act as a backup in case primary containment fails.
Treatment
Containing the contaminants is all well and good but if you can’t treat them, you’ll never be able to discharge. Fortunately, this is where we are here to help with a huge range of options when it comes to treating high alkaline wash water from concrete washout, hydrodemolition waste, or all types of silt or wastewater.
Treating concrete wash water
Our CWS system is a closed loop concrete washout system that retains solids in an adsorption sack and recycles the water meaning it only needs to be filled once not only saving time onsite, but massively reducing the amount of wash water wasted, which is both more sustainable and gives you less waste to treat reducing the chances of spillage or contamination. Additionally, with the help of our KT neutraliser, you can manually treat pH by adding it to the clean water you use to fill the tank.
If you’re looking for automatic pH control, the CWS Ultra or Double Washout would be the perfect fit as pH neutralisation is achieved by dosing CO2 directly into the filtered wash water. This combined with a higher volume pump for optimum hose pressure and a bigger capacity, make these the ideal concrete washout solution.
No power? No problem. We also offer single and double sack frames containing our adsorption sacks, specially designed to allow the fast flow of water whilst retaining solids and oil residue and allowing effluent to filter and drain.
Treating wastewater and silt
For wastewater and silt, our WTS water treatments systems are more efficient than traditional settlement tanks due to the chevron shaping and tube configuration of our coalescing/lamella media resulting in equal flow distribution, equidistant flow, and similar flow velocities which work together to ensure a consistent flow rate and avoid short-circuiting, which is a common problem with settlement tanks that use lamella plates rather than tubes.
This means rather than our system clogging, silt and sludge is collected in the hopper and can be discharged via a dump valve. Surface oils are no issue either with adjustable oil skimmers and the optional addition of hydrocarbon filter pads.
With a huge range of sizes and flow rates, as well as interchangeable coalescing/lamella media that can be provided with differing openings, our variety of WTS systems are customizable and adaptable, so are sure to suit your site’s needs. It can be equipped with remote monitoring, automatic pH control, and auto-desludging pumps, so can be adapted to any problem to give you an ideal solution.
Treating hydrodemolition waste
Our HpC is a hydrodemolition pH control system that separates solids and contaminants, as well as automatically treating the pH of the high-alkaline, cementitious wastewater making it safe and legal to discharge.
It combines several of our innovations with an adsorption sack for solid retention, automatic pH control, and the coalescing/lamella media for settling out stubborn suspended solids. This ensures that even the toughest waste to deal with is back under control, improving compliance and minimizing environmental impact.
Other options for treating hydrodemolition wastewater include our GWS hybrid which works in the same way as the HpC but is also low enough for concrete wagons to empty into.
Limited space? The GWS compact’s small but mighty build with automatic pH monitoring and correction makes it ideal for treating hydrodemolition wastewater on sites where saving space is a priority.
If you are dealing with contaminated water Kelly Tanks can provide bespoke solutions to help make your site more compliant and environmentally-friendly.
Get in touch today to see how we can help. |
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