There is no point spending a lot of money on chemical testing, analysis and, in due course, remediation, if you don't get high quality representative samples from site in the first place.
Traditional shell and auger techniques have become the accepted methods for soft ground sampling, despite their obvious technical failings and inefficiencies. There have been very few developments in the UK ground investigation industry over the years and the industry has continued to score own-goals by perpetuating the use of inappropriate contract procedures and out-of-date specifications.
More recently, window sampling has had some acceptance as a rapid and cost effective way of obtaining small and highly disturbed samples, but the technique has serious limitations.
Things are changing, however, both technically and contractually. Some site investigation contractors, including my own, have been working closely with geo-environmental consultants to develop new ways of taking samples for contaminated land investigations.
An example of the results of these efforts is our dynamic sampling technique, which has the ability to switch between dynamic sampling (a steel sample tube is driven into the ground by a powerful jack hammer) and rotary drilling as the hole progresses. This means that soft ground can be sampled and any obstructions, including rock and larger waste material in landfills for example, drilled through without sample loss.
Samples are continuous and nearly undisturbed. They are recovered in semi-rigid transparent plastic liner and are up to 110mm in diameter. And because they are sealed, this makes them especially suitable for contaminated land work. The sample is recovered and contained in a liner, so that no one need come into contact with it - the driller, client, consultant or the public - which has big health and safety advantages.
Andrew Milne, managing director, Geotechnical Engineering