Delivering results at least cost and with minimal disruption is especially important when it comes recovering contaminants at operational sites. A continuous process of innovation enables us to marry cutting edge technologies with engineering skills to find hassle-free, cost-effective remediation solutions. One such example is the development of a new radar probe for Light Non-Aqueous Phase Liquids (LNAPL) recovery.

RAISING THE BAR

Winner of the Brownfield Briefing Award in 2017 for Best Science/Laboratory Advance, Ecologia’s new site investigation tool represents a real game-changer that is reshaping the future of LNAPL assessment.

The new investigation tool offers improved efficiency, streamlining the assessment process through greater automation, with radar technology providing access to better quality data in a format that is easy for both engineers and non-specialists to understand.

Successfully deployed to date on a number of commercial projects across the UK, the advance in technology, combined with Ecologia’s long track record in bail-down testing and modelling enables the mobility of the LNAPL to be determined and the identification of remediation steps (if any) which may be required for recovery. The new approach helps in the setting of achievable remediation targets and the design of a remediation system that is cost-effective and fit for purpose.

UNDERSTANDING LNAPL BEHAVIOUR

Traditionally, the method to measure the mobility of the LNAPL, critical in judging the need for recovery, has been through a baildown test, in which a volume of LNAPL is rapidly removed from a borehole slug or well and the rate of fluid-level recovery (water and LNAPL) is measured and analysed.

The baildown test has been found to lack precision, generating results which do not always accurately reflect what is happening underground. It was this issue that led to Ecologia’s drive to develop a probe offering greater certainty.

Ecologia’s experience of fluid behaviour and measurement, combined with their R&D resources led to the launch of the innovative Automatous Monitoring System, which underwent rigorous testing in the laboratory and in the field to prove its reliability and precision before its launch last year.

HOW DOES THE NEW TECHNOLOGY WORK?

This latest system allows for critical measurements to be taken over an extended period, without the need for operatives, something that is especially vital at ‘high risk’ and operationally live sites.

By using our 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 are also — and arguably more importantly — able to identify the areas where it is recoverable, as opposed to a largely immobile saturation. The guided wave radar probe technology, which distinguishes the system design, provides much cleaner, more readable signals that allows for the positive identification of LNAPL interfaces with air and water during their movement in a well.

An  ongoing project in particular demonstrates the need to dig deeper in monitoring and analysing LNAPL behaviour on existing sites.

MIDLAND REMEDIATION CASE STUDY

A new LNAPL remediation project undertaken at an operational manufacturing facility in the Midlands, which has now been installed and commissioned, called for disturbance on site to be kept to a minimum. (see project award news)

Ecologia carried out an initial study to fully assess the extent of the contamination and the mobility of the LNPL. This entailed conducting a baildown assessment in combination with its automatous radar probe generating detailed data which indicated the pollutants were readily recoverable. The installation of a multi-phase extraction system under environmental permit has now been completed.

The preferred design comprises a smaller, more flexible system which extracts LNAPL through an array of wells installed underneath the factory floors. In order to mitigate disruption, the recovery wells were drilled diagonally outside the perimeter of the operational building. The wells are connected into batteries of five, providing a total of 15 extraction locations, operated cyclically. System telemetry and performance are monitored daily from the main office.

LNAPL is now successfully being recovered, with close correlation between the initial data with the monitoring and modelling carried out at the outset of the project. However, differences observed during recovery indicate the presence of different types of  LNAPL. Ongoing monitoring of system performance will determine whether operational changes need to be made to optimise recovery, and allow the conceptual site model to be continuously undated as more data is gathered.

Hailed by the Brownfield Briefing Awards as a development that was ‘novel and substantial …with a wide application in the sector’, the new technology could make a huge difference to the health of our environment going forward. In addition, project results to date establish beyond doubt that the extraction of LNAPL from contaminated land can be done in a way that maximises efficiency and safety, while providing continual feedback over more than 22 days on a single standard 72Ah battery.

Furthermore, the scope of the projects undertaken also demonstrate the customisability and flexibility of the new approach, even in the most challenging environments and working conditions. Read the full article