The QED HC-1 is a UK designed and manufactured instrument specifically designed to analyse for a wide range of petroleum and coal tar derived hydrocarbons. The QED can be set up in the back of a van, on an office desk or in a laboratory. It does not need expensive sample extraction systems or use environmentally damaging solvents such as dichloromethane, typically used in conventional laboratories. It is easy to use requiring only basic skills and has a comprehensive QC system to ensure valid data is generated.
The QED can, within a few minutes of taking a sample of road surface or subsurface, detect and identify if coal tar, bitumen or bitumen/coal tar mixtures containing as little as 1% coal tar is present. For mixtures, the result will indicate the approximate % of coal tar in the bitumen. If coal tar is detected, the approximate % of benzo pyrene in the coal tar (as required by WM3) is given. The sample cost is at least 10x lower than conventional laboratory analysis that meets the legislative requirements.
Sample extraction and analysis is very simple. A sample pot is filled ¼ full with small pieces of road surface sample. Extraction solvent is added until the layer of binder is covered. Nothing is weighed or measured, so no special equipment is needed. The sample is shaken for about 30 seconds and then a dip stick is put into the solvent and immediately transferred to the QED analysis cuvette and analysed. The QED analysis takes approximately 5 seconds. If the cuvette contains too much or too little sample, the QED QC system detects this and provides a dialogue box that tells the operator what to do to obtain a valid result.
The analysis is unaffected by temperature or sample moisture and only measures the extractable binder component so is unaffected by variability in %aggregate within the binder. If the identification is just bitumen based road binder, the arisings containing binder are non hazardous. If the result is just coal tar, the arisings will be hazardous. Binder content is typically between 3% and 6% in a road surface so even relatively low coal tar content in the bitumen may breach the 0.1% limit. Where a mixture is present, if the BaP content of the coal tar present is above 0.005%, according to WM3, the material is hazardous.
QED analysers provide reproducible results regardless of the operator, location or instrument used. This gives confidence to the contractor and regulator that data generated is reliable and fit for purpose. Results generated are easy to interpret and less open to misunderstanding.
As no accredited methods are actually available, it is possible to use the QED under the BATNEEC principle, Best Available Technique (technology) Not Entailing Excessive Cost, embodied in the Environmental Protection Act 1990. If the proposed technique is sufficiently reproducible, has an appropriate QC process to give confidence the data is valid and allows the user to comply with current environmental regulations, it can be used and the data will be accepted by the regulator. The QED can be used in a conventional laboratory setting and obtain UKAS accreditation as a single analysis method for the specific task of coal tar identification in road binder. Waste contractors, landfill operators and utilities labs in the UK currently operate QEDs and rely on the data that the EA also accepts.
When the QED is used by utility contractors, they are confident any arisings are correctly classified for WM3, minimising their liability. Where unplanned works are required, samples can be analysed on site during the excavation process. For planned works, cores are analysed at the contractor’s depot or sent to a lab that uses the QED. Sample turnaround is fast even if sent to a lab. The low per sample cost allows contractors to analyse individual bands of binder within a road surface without exceeding the usual low analytical budget. Coal tar containing binder is often found in discrete layers. By identifying which layers the coal tar is in, the contractor can specifically remove this material as hazardous. This reduces the overall tonnage of material sent to a hazardous waste facility and allows the rest to be recycled or used on the site as road base or backfill. This significantly reduces transport costs and the associated environmental impact of sending material to landfill. By getting rapid results the contractor can more efficiently manage the process, complete the job faster and significantly reduce costs, minimising the amount the taxpayer eventually pays.
The cost of conventional lab analysis that can reliably identify if coal tar is present is high. The cost of sending approximately 200 samples for this analysis is the same as a buying a QED analyser. The oldest QEDs are 6 years old and working well, proving reliability and cost effectiveness.
Using a QED significantly reduces the costs for utility contractors, speeds up road repairs, reduces the overall environmental impact of utility works and allows full compliance with current environmental regulations. A substantial benefit for taxpayers, road users and the environment.