Geo-Environmental Services
When a client rang and said they needed boreholes in a densely overgrown area, located up a high-sided kerb behind some hedges, we knew we had just the drill rig for the job. After checking for below-ground utilities, we completed seven boreholes locations to 4m depth in a single day. Naturally, we left the site clean and tidy, with a happy client.
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.
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.
Remediation is always challenging, but it’s made much harder when we are asked to do it at a busy filling station which needed to remain open throughout our works. Having previously determined that the contamination was confined to a relatively thin layer of gravel but was migrating offsite, we decided to install some small diameter sumps across the site in preparation for a programme of ISCO (treatment using in situ chemical oxidation).
Fitting the sumps between buried services was always going to be tricky, so we pre-excavated each location using vacuum drilling techniques. As you can see from the photographs, it was a good job that we did, with numerous pipes and ducts exposed (and duly avoided).
The excavation has now been backfilled and the pavement reinstated, leaving us with a small manhole cover to provide access to our sump when we return to start treating the ground. The filling station remained open throughout our works.
We like to believe that we work pretty hard, but it’s always nice to get a chance to get some time off. We’re lucky enough to work very close to some of the most beautiful countryside in England, within sight of the challenging Wendover Woods mountain biking trails. So when someone suggested a ‘team building’ day on the trials, we weren’t short of volunteers. I think you’ll agree they’re a fine looking bunch…and that was before the ride.
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!
We’ve been in business for over 25 years, and in that time we have worked at literally thousands of sites around the UK. So many, in fact, that we can’t always recall the details of each one. So, to aid our ‘corporate memory’, we’ve added a geo-location tool to our Prism software.
This quickly tells as all the sites where we’ve worked in any given area, which can be useful in determing the local geology or hydrogeology. It’s also useful in reminding us of where we’ve been!
Prism is our bespoke business and data management software. It runs our phones and email, our accounts, our laboratory, HSE and project management in one neat, intergrated package.
For more information about Prism please contact Duncan Eastland – 01296 739431.
…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
Not that kind of protection! We’re talking about cathodic protection of fuel pipes and tanks.
Decommissioning and replacing defunct cathodic protection ground beds requires an element of precision and brute force. Our first job is usually locating the existing beds. This can be no small task on a 30 hectare oil terminal site! The redundant beds were installed over 30 years ago and records are sparse.
We used radio detection methods to accurately locate the old redundant vertical ground beds to the required accuracy of +/-50mm. We need to be that accurate in order to successfully overdrill the beds.
Unusually, on our most recent project, our client asked us to drill through the connecting cables rather than removing them. The cables were isolated by a field engineer prior to us starting work and all our works were carried out under a permit to dig.
To overdrill the existing beds we brought in a shell and auger rig, drilling 350mm boreholes to 5m depth. This effectively decommissioned the existing redundant ground beds to make way for the new ones. With the first stage of the project complete, we are now back on site with our Comacchio rotary rig drilling much deeper boreholes in which we will be installing new anodes. Updates to follow.
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.