Case Studies
A range of case studies, demonstrating the diversity of our award winning land remediation services
Blyth: Purple Haze: Petrol Plume Fluid and Vacuum Recovery
Situated in a densely populated area in the North of England, a commercial petrol filling station required immediate attention following an emergency call-out by site staff. Migrating contaminants and extremely flammable vapour were uncovered during redevelopment, endangering the site residents if left untreated.
Following a brief from on-site staff, our team designed, built and installed a network of fluid recovery pumps to tackle the danger posed by migrating contaminants. To combat the hazard posed by flammable vapours, a vapour recovery system on the site was designed, built and put to work immediately to annul the danger posed.
Over a 6-month period Geo2 protected the immediate surrounding population from harmful emissions and saved the client around £300,000. The project saw a >99% reduction in dissolved contamination and a >95% reduction in volatile hydrocarbon vapour, protecting the circa 6 homes in the area from evacuation and reducing excess lifetime cancer risk.
Trafford: Tar Stabilisation and Chemical Oxidation
Historical infilling of a river channel with refinery wastes presented serious obstacles to the successful regeneration of a former industrial facility and gasworks site. The site was underlain by a thick 3M layer of acid tar, an extremely hazardous contaminant. As well as preventing commercial evolution of the site, regulators were concerned these refinery wastes posed a serious issue to a nearby watercourse. Left untreated, contamination could significantly degrade the surrounding aquatic environment, causing lasting harm.
A remediation strategy was quickly designed by our team. Here we aimed to stabilise the tars, encapsulating severely contaminated soils. As well as encapsulating the soil, stabilising the soil in this way allowed the soil quality to recover, enabling it to be used as a base for the foundations of a new development. For us, it is essential that our clients, consultants and regulators are confident in our work - work which often lays the safe foundations for the development of sites.
That is why here we worked with a specialist geochemist to produce a design we could place 100% confidence in.
Our phased treatment ensured that development could commence in key areas within 3 months. Within just 6 months all remedial objectives had been achieved, saving the client around £1.8 million. Through the reuse of material, accumulated throughout the project, our work was efficient and cost-effective for the client. By ensuring that less toxic soil ends up in landfill, being reused by our client’s customers instead, our work demonstrates projects can be both cost efficient and socially positive.
Anglesey: Dual Phase Vacuum Extraction and Chemical Oxidation
Decades of heavy industrial activity on a former aluminium site in Anglesey left a legacy of significant contamination. Diesel leaks from underground tanks, oil spills from industrial compressors and fire damage incidents leading to transformer oil spills left the site in need of immediate attention.
Rainham: Soil Treatment Centre for Hydrocarbon Impacted Soils
Hydrocarbon contamination of soil poses a serious risk to its renewable potential. Soil treatment centres aim to divert these hydrocarbon contaminated soils from landfill and treat them with enhanced natural processes to facilitate their reuse.
Geo² Remediation were asked to find a suitable solution, at a major soil treatment centre run by an international waste management company in the south of England.
Keswick: Hubble, Bubble Tar from Rubble - Keswick High Pressure Gas Site Thermal Remediation
An operational natural gas pressure reduction centre in the middle of Keswick, Cumbria, discovered hydrocarbon contaminants in a tar tank. Providing gas to over 3,000 properties, and located less than 11 metres from nearby residential homes, these contaminants put the surrounding population at severe risk.
The regionally important site continued to operate throughout the project without hindrance. In addition, no significant impacts were felt by surrounding stakeholders, with several complimenting the project team for their attitudes and behaviours
We worked alongside long-time contractors and site operators to deliver permanent environmental betterment by the removal of hazardous substances that threatened nearby controlled waters. Our remediation is cost-effective and efficient; this case study is no exception.
Enfield: Surfactant Enhanced Aquifer Remediation
On a former industrial site in London, an investigation identified a 100m plume of heavy oils floating on the groundwater beneath. Untreated, this contamination seriously threatened a nearby source of water, thus endangering the surrounding public.
Surfactant flushing was selected as a means to mobilise the oils from the ground and a series of recirculation cells established, with surfactants injected around the perimeter and recovered in a central abstraction well, flushing the chemicals through the ground.
We were able to remove approximately 80-85% of the mobile oils within the ground over a two-month period. Validation sampling ensured that Geo2 could demonstrate to regulators that the risks had been mitigated. We were able to quickly assess the issue, build a solution, and provide impact to our clients, who went on to develop on the former industrial site, saving them £100,000s in the long run.
North West: Enhanced Anaerobic Bioremediation of Chlorinated Solvents
A significant chlorinated hydrocarbon source (trichloroethylene, known as TCE) was found on a site that was being redeveloped into commercial units, threatening to disrupt its redevelopment in a heavily developed area.
Geo2 were asked to mobilise rapidly and remediate the impact to save the site for redevelopment, while ensuring no liability for future landlords. We proposed a series of direct push injections of Hydrogen Release Compound (HRC), that would speed up the biological degradation of chlorinated hydrocarbons.
This process enabled the pressurised application of chemicals at depth, allowing the team to apply the treatment media at different levels throughout the water column.
The rapid application suited a tight development timescale, working around and during the construction activity that was underway. Owing to the longevity of HRC, our job aftercare involved monitoring the land every month to ensure its full efficacy following the culmination of the project.
More than 95% of dissolved phase TCE contamination was remediated within a year, and breakdown of daughter products (dichloroethylene and vinyl Chloride), created as a result of TCE degradation, was achieved over a longer period, demonstrating the ongoing activity of the HRC.
By using specially adapted direct push drilling rigs, we ensured contaminants were accurately targeted, and maximum treatment was achieved from each injection. The method chosen also meant no permanent infrastructure was needed, so it didn’t disrupt ongoing building work at the site.
The work was completed with minimal disruption and no delay to the build programme at the site.
Crumpsall: Air Sparge Vacuum Extraction
Investigations at a Petrol Filling Station (PFS) site in Greater Manchester identified hydrocarbon contamination in the subsurface and groundwater. A subsequent assessment carried out by GEO2 led to the recommendation of remediation, using Air Sparging and Vacuum Extraction techniques to mitigate identified hazards.
Working within the scope of an ongoing forecourt refurbishment, Geo2 quickly installed a treatment system. This applied a vacuum to the unsaturated soils and used a compressor to bubble air through the water column via wells in the impacted area of the site, with the aim of stimulating natural aerobic degradation and reducing hydrocarbon contamination to “as low as reasonably practicable”.
The treatment system operated for a 12-month period. The system allowed for the continued observation of treatment progress and calculation of recovered hydrocarbons. Monthly monitoring recorded groundwater levels and any potential contamination rebound.
After 12 months, the treatment system shut down to allow validation sampling and monitoring over a period of 3 months. Of the six monitoring wells located across the treatment area of the site, lab testing of groundwater samples recorded marginal elevated concentration of hydrocarbons above SSTLs (Site Specific Target Levels) at just one location.
The remediation system was operated with minimal risk of harm or nuisance to site users whilst trading. Reductions of hydrocarbon concentration in shallow groundwater are now close to 90%, demonstrating efficient work that has saved the client resource in the long run and made the site safe and within regulation for future industrial use.
Immingham: Ad Blue Clean Up
Geo2 were commissioned by a major UK fuel distributor to environmentally assess and manage the redevelopment and expansion of one of their flagship sites.
Soil validation sampling from the sides and base of the excavation, following removal of historical underground fuel storage tanks, found strong ammonia odours seeping from the ground. Noxious fumes prevented the contractors from working, this caused project delays and threatened further costs for the client, especially as the source and nature of the release was unclear. The impact also posed several serious problems to neighbouring businesses who adjoined the site.
To continue with the redevelopment, these urgent health and safety issues needed to be addressed and the nature of the contaminants had to be determined at the source.
An investigation carried out by Geo2 concluded that the source was likely to be Ad-Blue, a diesel exhaust fluid used in HGVs and other diesel vehicles to reduce emissions. The product is based on industrial urea, and breaks down into ammonia. Investigation by the client discovered that there had been an incident with an Ad-Blue above-ground tank. It appeared likely that the losses associated with this leak had been vastly under-estimated by the third-party operator of the system at the time. Subsequent soil and water sampling, tested by a specialist laboratory, confirmed the leak source.
As there appeared to be no UK precedent, rapid action on determining safe site specific target values was required. This would establish a remediation work plan, detailing the methods with the client, contractor and regulators in order to progress safely, quickly, efficiently and legally. Remediation was carried out using mass excavation and disposal in the source area, to minimise the impact of the build programme.
As laboratory validation sampling of the urea was too time consuming, hand-held vapour metres were used to field screen materials during excavation. In addition, sediments from the sides and base of the adjacent water source were removed without causing further detrimental impact.
Final assessments were made by monitoring the adjacent watercourses. The results were as hoped and regulatory sign-off was achieved. The client was able to quickly proceed with redevelopment and sale of the site.
Throughout this project, Geo2 demonstrated an ability to act in an agile manner, safely remedying a problem that had not yet been seen in the UK. This was done efficiently, saving our client both time and huge sums of money.
York: Oil in the Bones
Inorganic (asbestos and industrial made ground) and (free fuel oil and hydraulic oil plume) and organic contaminants posed a serious risk to the complex development of a luxury property site in York. Geo² were tasked with providing specialist in-situ remediation.
Owing to the location of the development, which sat on a significant Roman and Viking archaeological site, the remediation project had to be carried out in a way that would not threaten underlying artefacts and remains.
Agreement on the final remediation strategy involved complex multi-party negotiations,
balancing the needs of both Environmental and Archaeological stakeholders. From these
negotiations, Geo² implemented a strategy that appeased all relevant stakeholders and the luxury developer.
This included piled barrier installation along the river face of the site - separating oils from the river - and the decommissioning and removal of oil infrastructure. The negotiations also concluded that excavation and removal of shallow oil hotspots and asbestos and metal rich made ground.
The remediation required targeted removal of deeply buried oil structures on-site (hydraulic jacks and nine fuel oil tanks), as well as a hotspot excavation and free phase skimming and pumped groundwater recovery to remove the source and much of the residual plume impact.
Risk modelling and monitoring enabled the safe natural degradation of the oil plumes on site.
Our collaborative and sustainable approach to this challenge delivered the best outcome for the client, balancing a cost effective service whilst preserving important archaeology and protecting the environment.
FAQS
Always invigorated by a new challenge, we are team players. Our open-minded approach and technical experience allows us to find genuine innovative solutions to save cost, reduce programmes and deliver quality where many other businesses cannot.
Geo² takes pride in delivering a bespoke solution which reflects the clients’ needs and the site-specific requirements. Our extensive catalogue of case studies showcases a range of in situ remediation solutions including Dual / Multi Phase Vacuum Extraction, Chemical Oxidation, Reductive Dechlorination, Enhanced Bioremediation and Thermal Desorption amongst others. Ex situ treatment techniques in the Geo² toolkit include soil stabilisation, biopiling and material management.
Geo² has many years’ experience working with fuel station and roadside retail clients, providing ground investigation services to purchasers and developers. In the event of a loss, we provide support for planning applications and working with contractors to resolve unexpected issues.
