Ecologia has developed a new and highly impressive method for site investigation and assessment of Light Non-Aqueous Phase Liquids (LNAPL) for contaminated sites. This award-winning new development is set to change the face of LNAPL investigation and recovery in a number of different ways. The benefits this impressive development offers include: the ability to make the process more automated, more efficient, and more understandable for both specialists and layman alike.
Ecologia recently gave a presentation on the novel system, “Advances in LNAPL Assessment for Cost Effective and Successful Remediation”, at the Envirocon Conference in London on the 17th May 2018.
To understand the background of this pioneering work, attention must be turned to the Irish capital. Proof of concept for the device was achieved as part of the recovery project undertaken beneath the railway arches at Dublin’s Connolly train station. The area is notable for its unusually high flood waters, which in this case displaced part of an LNAPL plume that had been lurking beneath the surface. The released LNAPL subsequently breached ground level, leading to high-level talks between Iarnród Éireann (Irish Rail) and Dublin City Council.
Preliminary site remediation works were undertaken to deal with the plume, which till then had lain undiscovered. After a marked lack of success in these efforts, a tender for recovery was issued by Iarnród Éireann. It’s at this point in the story that Ecologia come in.
The Kent-based remediation experts presented a proposal for a site remediation, which involved undertaking a full redesign of the recovery system in order to meet the budgetary requirement set for the project. The revised remediation scheme proposal not only met the improvement requested by the client, it actually exceeded it, and Ecologia were awarded the contract.
The Challenges Ecologia Faced
Having lodged an ambitious proposal, Ecologia were faced with a challenging task to achieve what they had proposed. Their attempts at site remediation were at the mercy of a number of factors, some of which were more serious than others. Arguably the most important factors that needed to be overcome included:
- Access: To recover the LNAPL, Ecologia would need to use a system to accommodate the one, small entrance that provided access to the tunnels under the arches. Machinery would need to be brought inside the tunnels, and then assembled in-situ if the company were able to complete the work as required.
- Working conditions: Air quality and working visibility were initially extremely poor in what was, after all, a confined underground space. This posed serious problems for the workforce, and had a dramatic impact on the potential productivity of the operation. This was resolved by installing a temporary dedicated air flow system, and more permanent lighting.
- Data quality: It was expected that there would be 130,000 litres of LNAPL under the surface to be removed. However, throughout the delivery of the project this had to be re-assessed and it was significantly revised.
Following the successful installation of an in-situ multiphase extraction system (MPE), Ecologia’s LNAPL recovery showed a significant decrease after the 1st year of operation. This instigated Ecologia to investigate the reasons associated with the decreasing recovery and a series of tests suggested to the clients in order to assess the effective mobility of the LNAPL in the light of recent scientific developments in the subject.
Positive Client Reaction
Of course, recognition from the environmental scientific community is one thing, but for Ecologia, there was another group of people whose approval was, if anything, more important. Stakeholders in their solution — for example, the Iarnród Éireann board who had hired them for the Connolly job in the first place — needed to be convinced of the efficacy of the solution.
Given that initial estimates had hinted at the removal of 130,000 litres — and the eventual total removed was to be a fraction of that — it was important that Ecologia be able to explain what they had done and how, and most importantly why, that was the ideal outcome. The presence of LNAPL in wells under the surface at the end of the project should not be viewed as a failure; though a layman might be inclined to consider it as such, careful consideration of the niche facts paints a very different story.
Perhaps most importantly over the duration of the project, one detail which Ecologia could point to was a massive 98% reduction in the mobility of LNAPL from the start to the end of the project. This was a particularly significant revelation because mobility is now recognised as the most important metric by which we can judge LNAPL recovery. While scientific exactitude does not allow us to say that all risks to the environment have been removed, a 98% decrease in mobility does mean that the level of risk has reduced to near the point of statistical insignificance.
Ecologia decided to hold a presentation workshop, which they used to explain the progress of their project and set out the important data on LNAPL mobility and recoverability. By the end of the workshop, all of the important detail had been explained to, and understood by, the stakeholders in the Connolly Arches project.
LNAPL Automatous Monitoring System Development
When it comes to removing LNAPL from contaminated land, until very recently there has been one way to go achieve it. A method known as a baildown test is used to measure LNAPL mobility— the most important detail in judging recoverability.
Historically, however, the baildown test has been found to lack precision, often generating results that bore very little resemblance to the reality beneath the surface. It goes without saying that this inability to generate reliable results was an issue that needed addressing with utmost urgency.
Ecologia proved that they were capable of addressing this need, and their ability to carry out the job in hand was demonstrated by their innovation of what they have called an “Automatous Monitoring System”.
The new device was developed on the basis of previous Ecologia’s experience on measuring fluid control. It was then tested in the lab and in the field (a refinery in Europe and at a number of site in the UK) to prove its reliability
This system allows the important measurements to be taken over a more extended period of time for better results, and all without the need for an operative to be present. At high-risk sites — such as in the work being carried out for Iarnród Éireann — this is essential, as there is no way for an operative to be present for the extended period required to obtain the measurements as required.
By using their Automatous Monitoring System, in tandem with reference to the CL:AIRE LNAPL guidance published in 2014, Ecologia are now able to identify the areas where LNAPL is present in large quantities. They were also — and arguably more importantly — able to identify the areas where it is recoverable also, as opposed to an immobile saturation. Ecologia can achieve this with the use of guided wave radars, which provided much cleaner, more readable signals that allowed for identification of mobile LNAPL.
The development of this monitoring system didn’t just make life easier for Ecologia, though. It secured them victory in the “Best Science/Laboratory Advancement” category at 2017’s Brownfield Briefing Awards. In the words of the awarding judges, this “novel and substantial” project stood out as something that “should have a wide application in the sector”.
Thanks to Iarnród Éireann’s belief in what Ecologia have achieved — and the undeniable overall success of the Connolly project — there is now no doubt that the extraction of LNAPL from contaminated land can be done in a way that maximises efficiency. Furthermore, this new method allows site investigation to be done remotely, which permits constant feedback without the need for an operative to be present in the (often hazardous) area where work extraction and investigation are necessary.
It means also that — particularly on sites similar to the Connolly project — the issue of contaminated land can be addressed effectively, affordably and speedily. The numbers speak for themselves: as well as a 98% reduction in mobility, Irish Rail saved hundred of thousands Euros over the course of the project by optimising the recovery system and reducing the overall length of the recovery operations from an estimated 4 years to 3. What’s more, the longevity of the novel system should be noted as particularly impressive: on a standard 72Ah battery, the Automatous Monitoring System can last for more than 22 days.
Additionally, winning at the Brownfield Briefing awards marks Ecologia, and this project, out as something that will revolutionise contaminated land treatment and could make a huge difference to the health of our environment going forward. Better yet, the Connolly project shows that a innovative methodology such as LNAPL measurement can be turned into an innovation which is customisable, and can be used even the most awkward and challenging of settings. In short, the future is bright for Ecologia— and that means it’s bright for the rest of us, too.
Giacomo MainiManaging Director
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David HolmesTechnical Manager
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