Investigation – Subadra

14 May, 202314 May, 2023

When Skimming is a Good Thing

OK, so when someone says they’ve been skimming, it’s not usually a good thing. However, when it’s skimming fuel from a monitoring well on petrol station, that’s definitely beneficial.

We identified the fuel during a site audit, carried out in response to complaints about petrol odours in off-site (BT and Thames Water) service ducts. Contaminants often track/migrate through ducting and service trenches, leading away from the original source. In this case, our detective work was able to trace the source of the odours back to a fuel leak from the nearby filling station.

Our UKAS accreditted laboratory carried out forensic analysis of the recovered fuel in order to determine it’s age and composition, allowing us to further focus future infrastructure and ground investigation efforts on possible sources of the leak from the filling station.

Being able to seemlessly integrate both site investigation and laboratory testing in this way resulted in significant time and cost savings for our client.

If you’d like to know more about our unique approach to assesment of contaminated land, please contact James Edley.

9 August, 2019

It’s What You Can’t See….

We were asked to carry out an environmental ground investigation at a disused transport depot. Not surprisingly this identified diesel contamination at ~2m below ground level.

There was no sign of any obvious contamination source and given the site’s previuous use as a transport depot, we thought it likely that an abandoned below ground fuel tank might be present.

We therefore went back to the site and carried out a shallow trial pitting exercise which revealed……well, you can see for yourself.

12 October, 2018

Hollow Stem Augers

Up Close and Personal – The Business End of a Hollow Stem Auger

The site investigation industry has, traditionally, relied on light cable percussion (generally known as shell and auger) drilling. This is slow, messy and crude providing low quality geotechnical and environmental samples at best. Thankfully, these days it isn’t the only option available to you.
The majority of our general site investigation drilling is done using hollow stem rotary methods. These provide signficantly better quality data with minimal sample disturbance, even in the toughest of conditions. This week we were working at a site underlain by glacial and millstone grit cobbles, sand and terrace gravels in a sandy clay matrix. We drilled five boreholes to their target depth on 8m in one working day – something that might have taken a shell and auger crew a week – minimising the disruption to our client’s business which was able to remain open throughout.

12 October, 201812 October, 2018

Leaks and Spills

We’ve recently started the first phase of our latest remediation project: the redevelopment of a former petrol station site located in a highly environmentally sensitive location.
Stage one of our work comprised identifying and removing the source of the contamination. As you can see, we are pretty confident that we found the root-cause , although we have to wonder how the former site operator didn’t know something was wrong with this tank.
We’re currently working to design and integrate our groundwater treatment system with the construction work to ensure that there are no delays to the redevelopment.

5 September, 201818 September, 2018

Why Coring Isn’t Boring

It probably comes as no surprise that it takes a very different skillset and completely different equipment to core through rock as opposed to boring through the sand and clay soils that are more commen near the ground surface.

The correct core bit (i.e. the part of the drill string which cuts the rock) selection is the key to obtaining high quality quality core samples. Each rock type requires a specific core bit to cut it cleanly and efficiently. So, to achieve the best results, we carry a range of different core bits with us at all times. Our drilling crew recently used our T6 coring barrel to core to depths of 25m in a range of geology from conglomerates to slate and everything in between.

So, you might say that coring is not boring. Fact!

13 August, 201825 September, 2018

You Never Know….

…what lies beneath your feet. But when it comes to carrying out any form of ground investigation or excavation work, it’s imperative to find out whether there are any buried pipes or cables before you start work.

We provide consultants and contractors with the information they require, whether it’s a complete set of public utility drawings or a remote sensing survey using radio detection and ground probing radar.

For more information, please contact Angus Gale – 01296 739333

13 July, 2018

Where There’s Muck There’s Brass

Last week we undertook window sampling and installed monitoring wells at one of the largest recycling processing depots in the UK. Have you ever wondered what happens to your recycling after it gets taken away? Well it will likely end up at a processing centre similar to this one, where the waste is separated, segregated and prepared for recycling.
It was eye opening to see the scale of the operation. Usually when we drill, our rig is one of the bigger vehicles on site, but this time our van mounted Geoprobe was dwarfed by some of the other machines on site.

6 July, 2018

Heathrow Third Runway

OK so we can’t say whether this will (or should) get the final go ahead from government. But what we can say with absolute confidence is that we have more experience of working airside at Heathrow than any other geo-environmental consultant.

We are the only consultant with permanent airside passes, both for our staff and our vehicles. We are also well versed in navigating our way through the airport’s complicated permiting system.

Just last week one of our investigation teams worked through the night to install several deep monitoring wells adjacent to one of the existing runways. The third runway will need thousands of similar geotechnical borehole drilling in the next few years. We believe that having an airside presence and an in depth knowledge of the geology gives us a head start when it comes to providing this service.

For more information please contact James Skinner – 01296 739411

6 July, 2018

The Good Old Days

We recently came across this advice in a 1960s ‘How To’ manual.

We think the Environment Agency might have something to say if anyone advised this now. But it is typical (albeit on a small scale) of many of the less enlightened environmental practices from earlier times.

This goes some way to explaining why so much of our brownfield land is contaminated in one way or another. With soil and groundwater clean-up costs increasing all the time, it also points up how foolish it is to buy brownfield land without first checking on its condition.

If you’d like to know more about our geo-environmental site investigation capabilities or if you have land that requires treatment, then please contact Duncan Eastland – 01296 739431.

6 July, 2018

Cathodic Protection

Drilling large diameter boreholes at a brownfield site to install anodes for a cathodic protection system requires a rather eclectic combination of skills.

Working in a tight space, to a detailed specification, we achieved an anode installation through a complex sequence of geological strata. Clean drilling techniques required us to install an environmental seal through surficial gravels and 30m into underlying clay. We then extended the boreholes through 20m of Thanet sands and 10m of flinty chalk. To complete the anode installation we then tremmied sacrificial coke contact media into the borehole’s response zone with the remainder of the boreholes being grouted back to the surface with bentonite.

Our team consisted of drillers, environmental engineers, mud technicians and cathodic protection engineers, all working together on a busy site to ensure the client got the installation required whilst working within the Environment Agency guidelines. The anodes will now ensure the pipelines are protected for the next 100 years.

If you’d like to know more or if you have an installation requiring cathodic protection be installed then please contact Angus Gale – 01296739433