by Diarmaid Connaire, CDEnviro Business Development Manager
Non-destructive digging (NDD) and directional drilling practices are more popular than ever in infrastructure development and remediation because of the assurance of better accuracy and control near sensitive areas of land; however, this growth in the industry has increased the waste burden for many drilling operators.
Trenchless Technology has advanced in recent years, but the water involved within a wet cutting or boring process contains both chemicals and slurry that is problematic to handle, dispose of, or reuse responsibly. Although much safer, NDD and directional tunnelling practices have complicated the waste handling burden, creating a double-edged sword for all involved.
The thick nature of muds containing sand, clay and bentonite creates issues when processing the water. The disposal of this solid/liquid waste would be unlikely at any landfill site; even if it were accepted, it would usually incur a large cost due to its nature and weight.
Furthermore, ‘waste’ material contains many useful, reusable materials that can be recycled and made available for resale. With an increasing focus on the circular economy and more stringent legislation, there is an increasing need for urban recycling solutions instead of rural dumping grounds.
Between a rock and a hard place
Among the most common disposal methods, there does not seem to be a viable option – only a lesser evil. The best from a bad bunch is the landfill disposal method.
Sending drilling muds to landfill may remove the waste burden from the drilling company, but it is costly and detrimental to the environment. Not only that, landfill sites will not always accept this waste due to its thick state.
Meanwhile, the other options are worse, including burying the waste or ‘drying’ the mud in ponds or fields. This not only leaves the waste owner open to future legal implications, but also can be extremely damaging to soils and land.
If leaching occurs, contaminants – such as hydrocarbons, total petroleum hydrocarbons or others – could be released into the water table.
These contaminants can take decades to dissolve and often spread to, and contaminate, other areas. If environmental testing proves that leaching has occurred, the waste-owner may have to shut down their business as a result.
More often than not, these impacts are completely unintentional on the company’s part; however, it seems that the waste-owner may feel that they have no other viable option.
Waste treatment
Treatment of drilling muds is the safest option for the businesses involved and for the environment. Although much safer, sending the NDD/hydro excavated waste for processing by a waste-processing company is not without its challenges either.
The Environmental Protection Authority (EPA) in Victoria sets out strict guidelines with regards to the transport of industrial waste from drilling mud.
The regulations state, along with other factors to consider, that: “The drilling mud must be transported in a vehicle that is safe, secure and leak-free. Prior to transporting drilling mud, the waste transporter must ensure that there is no contaminated residue or material in the tanker/tanker trailer.”
Breakdowns, accidents, and spillages are among the various challenges that a waste-owner can face, not to mention the cost involved.
Safe and secure transport methods must be assured before even considering transporting the muds to another site. In addition, the company with the waste-burden must be aware of what happens to its waste after it is sent for processing.
If the waste finds its way in to soil or land by accident, the company with the original waste-burden could still have to deal with future legal implications.
Waste treatment onsite
Treatment of the muds onsite brings double benefits.
The first advantage of this option is the most obvious: the removal of risk. Effective treatment technology used onsite removes the potential jeopardy involved in transport, while also protecting the company with the waste-burden from possible legal impacts.
The second benefit is less obvious, but equally appealing: advancements in technology mean that waste treatment onsite can not only dewater any clay content of the muds to ensure cheap disposal of the material but also can recover valuable materials. These materials can include sand, stone and organics, producing independent revenue streams.
CDEnviro provides bespoke reception centres for NDD, recovering these materials for resale or reuse. Not only that, the recovered water can also then be treated for reuse.
This give operators greater control of their waste; greater sustainability, reduced disposal costs and materials for resale and reuse.
Perhaps most importantly, the technology provides the answer to the waste burden, ensuring that those conducting sustainable methods, such as NDD, are no longer stuck between a rock and a hard place; with effective technology, NDD/hydro-excavation no longer has to be considered a double-edged sword.
For more information visit the CDEnviro website.
If you have company news you would like featured in Trenchless Australasia contact Journalist Chloe Jenkins at cjenkins@gs-press.com.au