To complete the investigation, a 20 x 20m grid was laid across the site area and 50 trial pits were excavated to a depth of 1.00m bgl. A sample from each of these (at various depths) was taken for an asbestos screening, with five samples testing for a suite of contaminants. This was to confirm where the asbestos contamination was within the site.

From this first stage of the investigation, four trial pits were noted to contain asbestos, however two of these were insignificant from quantification. This meant that two of the 20 x 20m areas within the site had to be remediated. This would normally require soil from a 20m radius from the asbestos hotspot to a depth of 600mm would have to be excavated removed and replaced. Equating to around 1,500cu.m for both hotspots, the cost for the client was considerable. We therefore recommended further works.

Ground & Water’s approach had already saved the client a huge amount of money, as the whole site no longer needed to be stripped and remediated. The cost could be reduced further with a second investigation.

The return Investigation

 The focus of the return investigation was to narrow down the radius that needed to be remediated, if there was no contamination found. To determine the extent of the asbestos within the two contaminated 20m radius areas, our proposal was to take two more samples, within these areas, to try and reduce the remediation area (depending on the extent of the hotspot). This targeted sampling was undertaken and the samples at various depths were sent to the lab to undergo asbestos screening.

Because of our suggested return investigation, we managed to reduce the size of remediation needed from a 20m radius to a 5m radius. This was due to the extra sampling and proving the outer parts of the area were clean, narrowing down the hotspots on-site. This saved our client thousands of pounds in remediation costs and material removal and disposal. This massive saving was achieved, simply by taking a few more samples of the hotspot areas.