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I like this. Informative too! Kind regards Ruth Ruth Willcox Planning Officer Strategic Planning and Infrastructure T +441752304154 E [log in to unmask] www.plymouth.gov.uk -----Original Message----- From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of Colin Green Sent: 02 July 2018 10:29 To: [log in to unmask] Subject: Composite sampling Hi Mike Composite sampling can be useful as previously described to get an "indication" about potential contamination issues. The real issue this brings up however is the generally low sampling (and therefore analysis) densities seen when assessing potentially contaminated sites or for classifying stockpiles. Several papers over the years have highlighted this problem, and recently Professor Mike Ramsey from Sussex University has shown on several occasions how the confidence in data quality suffers when too few samples are taken. Even with a grid of 20m x 20m and taking a sample at every 0.5m depth, this equates to a volume of 200 m3, which equates to around 26 standard muck away lorry loads. On most brownfield sites sample homogeneity is poor, so the possibility of a lorry load containing significantly more contamination than the single analytical result obtained for these 26 lorry loads is high. In my experience a 20m x 20m equivalent grid is somewhat rare with 35 - 50 m grid equivalents quite common. A 30m x 30m x 0.5m grid equivalent would require 58 standard muck away lorries to remove. The new rules that came in force in April this year now significantly increase the costs and consequences of inadvertently (or intentionally) mis classifying soil for disposal as non hazardous when it is actually hazardous. Similarly, disposing of soil as hazardous when overall the soil is non hazardous is also an unnecessary expense at around £2,000 per lorry load. Appropriate sampling and analysis is therefore very relevant to the overall cost of a remediation. I hope the new sampling standards will help address this issue. The latest generation of in situ analysis methods such as XRF for heavy metals or UV fluorescence for hydrocarbons and PAHs can also be used to provide the increased sampling densities and provide results that are equivalent to laboratory methods, but at a significantly lower cost. Deana Crumbling et al from the US EPA in 2003 (Crumbling, Griffith, Powell : REMEDIATION Spring 2003) showed how higher sampling densities using just low resolution semi quantitative in situ methods produced higher overall data confidence in the CSM. This approach has been successfully used to assess allotments in the UK. I am intrigued by the cluster sampling example. I would have thought that if 5 samples were combined, the concentrations of the combined result should be multiplied by x5 to give the maximum theoretical concentration in a single spot. This value can then be applied to the agreed site limits. I would be interested to see the draft sampling guidelines. I come from a time when the old DD0175 was in use (or not actually used as was the usual case!!) Regards Colin Green ######################################################################## To unsubscribe from the CONTAMINATED-LAND-STRATEGIES list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CONTAMINATED-LAND-STRATEGIES&A=1 ******************************************************************************************************************************************** IMPORTANT: This e-mail (including any attachments to it) is strictly confidential and intended solely for the person or organisation to whom it is addressed. It may contain privileged, confidential or sensitive information. If you are not the intended recipient, you must not copy or distribute it to any other person or take any action in reliance. If you have received it in error, please notify your system manager and the sender as soon as possible and then delete it from your system. ######################################################################## To unsubscribe from the CONTAMINATED-LAND-STRATEGIES list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CONTAMINATED-LAND-STRATEGIES&A=1