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DEFRA has recently estimated that £210 million per annum is spent unnecessarily on UK remediation due to poor site investigations. There are several reasons for this, but the high uncertainty created when constructing the conceptual site model by using the analytical results from very small number of samples is a major reason. On-site analysis can be used to increase to number of samples taken, allow on site staff to direct where samples should be taken rather than making an educated guess and identify the contamination type and possible source. Significant savings can also be made during the remediation and soil treatment process.
The On-Site methods used by QROS produce analytical results within minutes of taking a sample. The speed at which results are generated from samples can be a huge advantage when investigating contaminated land, analysing road arisings etc. The primary advantage is that the investigators can react to data as it is generated. If road surface material is identified as non hazardous it can be reused, if hazardous it can be removed immediately so that the project can be finished with the minimum of delay. If an area of land is identified as being contaminated the sampling pattern can be adjusted to accurately follow the contamination plume, and completely delineate the extent of the contamination. This removes the expensive requirement for multiple returns to the site to effectively complete the investigation.
On Site analysis techniques can analyse more than 50 samples a day. The more samples that are taken the better the conceptual model for that site becomes. Having a good conceptual model reduces the risk associated with uncertainty and inevitably leads to a lower overall remediation cost. The combination of fast results to manage the investigation and a higher sampling density allows an effective site investigation to be completed that has a robust conceptual site model that minimises the unexpected. The cost to do this is also much lower than using just laboratory analysis. On Site analysis is typically 4 – 5 times lower in cost than laboratory analysis.
Remediation or Disposal?
QROS has undertaken numerous projects where remediation of the soil was required with the rapid results allowing the contractor to fine tune their equipment/techniques and be confident that the treatment process was working to its full potential. In the case of hydrocarbons the information that QROS provides can also be used to indicate the suitability of the material for the remediation process. It was this approach conducted by QROS that primarily allowed the Olympics Groundworks Enabling Scheme to be completed three months ahead of schedule.
The old way of stockpiling potentially contaminated material on site or, if space is limited, sending the spoil off as contaminated can increase cost significantly. Waiting for laboratory results, even for 24 hours, means plant can remain idle, excavations left open or even temporarily refilled requiring re-excavation. Using QROS allows decisions be made within 10 minutes of the soil sample being taken.
The rapid nature of the testing provided by QROS also allows the contractor/consultant to decide if spoil can be sent off site or to an on site treatment process as it is excavated and/or loaded. If being sent off site, the soil can be correctly designated as hazardous, contaminated or inert.
With landfill costs running at up to £500 per lorry load for polluted soil and £3,000 per lorry for hazardous waste, it pays to make sure that each lorry load is what you think it is before it goes off site.
The validation of a remediation can also benefit from on-site analysis. On Site results can show that the area previously identified as contaminated has been removed and give confidence that the laboratory testing will also confirm that the area has been cleaned. Backfilling or concrete pouring can continue immediately minimising down-time for plant machinery or workforce. Soil going through an on site treatment process can be checked and used immediately, removing the need for more stockpiling.