MONITORING & METERING FEATURE
MONITORING THE SITUATION with FTIR analysers
As it appeared likely that the fire and
Following the Buncefield Oil Storage Depot incident, it was decided there was a need to rapidly co-ordinate the acquisition, analysis and interpretation of air quality data in major incidents. So, arrangements were made in England to form an AQC (Air Quality Cell) for any major incident threatening significant air quality impacts, which will deploy field monitoring teams using Gasmet FTIR analysers supplied by Quantitech
I
n July 2014, a fire broke out at a recycling facility in Swindon. Initial reports from Wiltshire Fire and Rescue Service (WFRS) indicated that around 1000 tonnes of waste was on site. PHE (Public Health England) staff identified that the immediate area (within 250m) of the incident was mainly industrial and commercial use, with the nearest residential properties being approximately 400m away. The EA (Environment Agency) and PHE then discussed whether or not an AQC was required. The decision to convene an AQC will only be activated where: (a) there are potentially significant public health issues; (b) a suitable command and control structure is in place; and (c) the duration of incident is likely to be more than eight hours. Once established, an AQC typically operates for up to three days or until the acute phase of the incident is over. If equipment is deployed, the AQC
decides on the monitoring locations, taking into account meteorological conditions and the location of nearby human receptors. The field monitoring teams carry a range of equipment including a particulate matter monitor and a Gasmet FTIR analyser to measure a variety of volatile air pollutants. Dependent on the nature and profile of the fire, a mobile laboratory can be deployed to provide more detailed air quality data. The Gasmet FTIR analysers measure
ambient gases, so non-heated versions (DX4030 or DX4040) are used by the AQC. Sample gas is drawn into the analyser with a built-in pump through a handheld particle filter and Tycon tubing. This runs continuously, measuring time-weighted averages of user definable length from one second to five minutes. Capable of sub-ppm detection limits without using sorbent
traps for sample pre-concentration, the analysers provide fast response times. With the standard gas library, the
DX4040 can detect 25 different gases simultaneously, although this can be enhanced with Calcmet Pro software, which gives the user access to a reference library of over 250 gases, and 50 gas measurement capability.
THE SOLUTION Initially it was decided that the criteria necessary for establishing an AQC had not been met but that the situation should be kept under review. But, as the situation developed, it became apparent there was the potential for an extended burn time with possible impacts on the environment and public health. A multiagency tactical coordination group (TCG) chaired by the police was then set up to coordinate the multiagency response. The EA and PHE representatives agreed to convene an AQC, with Swindon Borough Council (SBC) being invited at the early stages. Suitable monitoring locations were
identified and air quality monitoring teams and equipment were deployed. SBC undertook its own particulate monitoring using three particulate matter monitors, with the data interpreted by PHE and fed back to the Council and the tactical coordination group. This monitoring data was useful to supplement the AQC monitoring data and provide public reassurance once the AQC had stood down. The AQC reviewed the initial air quality
monitoring data captured by the monitors and advised the TCG that the 24 hour averages were below the national air quality standards and were unlikely to significantly impact on public health. However, due to the substances present in smoke, the TCG was advised that public health messages should remain in place.
resultant smoke could continue for a number of weeks, SBC made the decision to continue monitoring for particulate matter for public health reassurance purposes. To facilitate this, SBC obtained three air quality monitoring stations. After a few days, it became apparent that the Fire Services were unable to make good progress and actively fight the fire due to the large volume and height of the compacted waste and a lack of physical space. In order for fire breaks to be established and active fire fighting to take place, it was necessary for 3000 tonnes of un-combusted waste to be removed from the site. A strategic coordination group (SCG)
was activated to assist in finding alternative locations for the waste, which was to be checked and dampened down as a precaution prior to leaving the site. Under normal circumstances an AQC would not be redeployed to the same site during a single incident. However, it was agreed that a second AQC
would be needed. The monitoring results indicated that, even when active fire fighting commenced, the plume showed similar characteristics to that recorded during the first AQC period. Occasional peaks in particulate matter concentrations were
noted, and the advice remained that people impacted by the plume should shelter and minimise their time outdoors. Before the start of active fire fighting,
residents and businesses were informed to expect an increase in the amount of smoke, and that active fire fighting was to be undertaken during hours when meteorological conditions would allow dispersal. Phil Chappell, air quality
The Gasmet FTIR
instruments are a critical component of the air quality major incident response service
manager of the Environment Agency’s
National Incident Management Services, said: “The Gasmet DX4030 instruments we procured in 2009 are a critical component of our air quality major incident response service. The ability to quickly deploy a single instrument capable of simultaneously identifying and determining the concentration of a wide range of gases is essential to the rapid assessment of the risk to the health of the public and to the environment posed by large fires such as the one at Swindon.”
Quantitech
www.quantitech.co.uk
INSTRUMENTATION | JULY/AUGUST 2016 15
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