A site investigation can be as simple as a walkover and trial pit or as complex as a series of boreholes and soil samples taken away for analysis. Picking the right site is not always easy, but it is far better for you to put some time and effort into a site investigation to choose the correct location.
Every site needs to check for problems or potential hazards. The depth and scope of this investigation will depend on several factors.
Location of site.
In many cases, a simple walkover of the site can provide several clues as to the nature of the site. There are several items that you need to be on the lookout for. If you are buying a green field site, you need to look at the vegetation on the site. Are there any plants that would suggest marsh or poorly drained soils? What condition do you find the top surface? Is it wet? If it is, has it been raining or mainly dry?
If it is a brownfield site, what was the site used for before? Was it a storage facility? Factory? Car park? It has been known for brownfield sites to be contaminated with chemicals due to spilled waste. Any site is known to have been a storage facility or factory with a qualified geologist who will perform a series of specialized Preliminary Site Investigation to help answer most of your questions.
Please be aware that while these tests are designed to be as accurate as possible, it is not unknown for hazards to escape detection. You must be as careful as possible and, if in doubt, do more tests. Sites likely to be contaminated include but are not limited to the following:
Chemical plants or storage facilities
Oil storage and distribution sites
Tanneries
Railway sidings and depots
Mines, smelt works, foundries, and metal workshops
Sewage farms and sludge disposal sites
Any industry using a wood treatment
Filled sites.
Is there any evidence that the site has been filled in at any time in the past? Detailed Site Investigation needs to be done carefully. Indiscriminate dumping into a filled site can leave any number of nasty surprises waiting for the unsuspecting self-builder. In addition, gases can build up beneath your home over time, creating a distinctly unhealthy environment.
Another problem is that of building waste being buried. It can range from concrete and building blocks to metal fences, drums, and plasterboard wastes. This problem is not the concern it once was, as health, safety, and environmentalists have clamped down firmly on this kind of indiscriminate dumping. But it still goes on.
It may seem strange, but I have encountered it several times. Many people look for derelict or abandoned buildings in the countryside, expecting that the planning authorities will look favorably on the application. Most of the time, this works out just fine, but now and then, you will come across a derelict building with a condemned order.