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Satisfying Planning Conditions

Look What We Found....

Environmental planning conditions are commonplace in brownfield development and much of our work is involved in the negotiation of discharge of such conditions. We have developed excellent relationships with Planning Authorities and Environment Agency/Scottish Environment Protection Agency over the years and enjoy a good success rate in planning condition discharge.

Earlier in the year Subadra were commissioned to assist in a significant phased retail development on the south coast of England. The site is within Zone I of a Source Protection Zone, overlies Chalk and is 40m from surface water. In other words it is in an extremely environmentally sensitive location. Initial investigation works had identified diesel and waste oil in shallow groundwater under the site.

This is where owning our own drill rigs and our own laboratory comes into play! We were able to delineate and characterise the contamination, and install sentinel wells within a month and without delaying the build programme. As a result of our detailed assessment, we’ve negotiated a long-term remedial solution for the site, installed the required groundworks and construction works have commenced.

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Successful Technical Presentation….

Contaminant Contour Plot

Otherwise known as ‘understand your audience’.

We have recently completed a highly complex site investigation and detailed risk assessment of a public amenity site on behalf of a Local Authority. Our technical report, however, needed to be understood by a wide range of stakeholders, including regulators, consultants, site users and the general public. We used a range of graphical presentation methods in our report, cut the industry acronyms to a minimum and offered a report written in ‘plain English’. The result? Clear advice and a happy client, who described our report as ‘a model of site investigation & risk assessment communication’.

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When Wetstock Monitoring Doesn’t Work

It has become increasingly common in recent years for filling station operators to rely on remote wetstock monitoring to detect possible leaks in their system. Tank and pump gauges are monitored remotely with sophisticated trend analysis used to detect abnormal behaviour. These systems can be very good, but they aren’t infallible.

Last year Subadra were retained to clean up contamination resulting from a leak at a filling station. Our treatment was completed successfully over the winter months and by mid-summer we had started post-remedial monitoring, with groundwater samples taken at monthly intervals from monitoring wells we had installed at the site.

Our consultants noticed some anomalous results appearing and, in best CSI fashion, our laboratory carried out a programme of forensic analysis. This was able to determine the ‘age’ of the contamination we were finding, telling us how long the leaked fuel had been in the ground. This confirmed that the wells were being contaminated from a new source.

The site’s real-time remote wetstock monitoring was checked but didn’t show a leak at the site. However, on our advice, the site operator had the tanks and lines pressure tested and this identified a steady slow leak from one of the pumps. Repairs were carried out limiting the volume of fuel lost into the ground.

The moral of the tale? Well, remote wetstiock monitoring is very good and we would certainly recommend it. But it’s not infallible. In those cases, forensic analysis can help identify leaks that wetstock monitoing misses.

If you’d like to know more about our forensic analysis service or any of the other services offered by our UKAS/MCerts accredited laboratory please contact Kate Clark.

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Water, Water Everywhere

Treatment System in Operation

We are currently assisting in the treatment of construction wastewater from a filling station redevelopment in Dorset. Working with the primary works contractor, we provided a system that is capable of pumping and treating high volumes of hydrocarbon-contaminated water from deep excavations.

Our in house designed, modular treatment plant was efficiently dealt with two both suspended solids and hydrocarbon contamination, ensuring all the effluent met the site’s discharge licence conditions.

We installed and tested the system at an early stage of the works allowing us to collect and analyse samples in our UKAS accredited laboratory and use this information to assist in obtaining a temporary discharge license from the local sewerage undertaker. This meant the
contractor was able to discharge effluent direct to the foul sewer.

With the high costs and project delays associated with tankering hydrocarbon-contaminated wastewater from site our fully mobile and modular dewatering systems are a simple and cost effective way of dealing with dewatering effluent.

Project value: less than £10k

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Subadra Awarded Multi-site Remediation Portfolio

We have been awarded a major remediation portfolio by one of the UK’s biggest fuel retailers. The multi-site portfolio will see us working at a sites across the UK using a wide variety of both in situ and ex situ remediation techniques. We understand that a key reason for us winning this work was our ability to provide cost-effective turnkey solutions, integrating site investigation, laboratory testing, fate-transport modelling and remediation design and implimentation using solely in house resources.

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Foundations for Key City Data Centre

Whilst much of our work in carried out in the provinces we sometimes dabble with high finance in the City.

Subadra played a key role in the development of an £80 million multi-storey data centre facility in London’s docklands area. We were brought in at the inception of the project to carry out a geotechnical and environmental investigation to determine ground conditions.

Our investigation comprised a network of boreholes across the development area that were used to collect soil samples for analysis and groundwater and hazardous gas monitoring points.

The site was especially tricky geotechnically, comprising areas of in-filled docks, some highly contaminated and others containing very soft silts and clays.

We used the data to assist with foundation design and the classification of waste soil.

Contract value: £20-50k

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Remediation Following Filling Station Fuel Leak

It’s not often that we post anything about our remediation projects. Mostly this is because they are often covered by confidentiality agreements and sometimes because they are too complex to be neatly summarised in a few paragraphs. So it’s nice to be able to report the successful completion of a remediation project at a filling station site in London. Over the Christmas holiday one of the tanks at the site was found to be leaking. The site is located in a very sensitive area environmentally: in a source protection zone and directly above London’s chalk aquifer. Despite the holiday festivities, we were able to mobilise a drilling team to the site. Our investigation quickly delineated the contaminated soil, with our in-house laboratory reporting their analysis results within 48 hours of sampling. This in turn meant we were able to excavate and treat the soil before the leaked fuel had a chance to penetrate to the underlying aquifer, saving our client from having to carry out a costly and time consuming groundwater treatment.

Contract Value £10-20k

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From Scrapyard to Parkland

Subadra have completed the successful transformation of a former scrap yard site into a public open space – on time and under budget.
Subadra, acting as Principal Contractor, have recently completed the investigation, remediation and landscaping of a 0.3ha former scrap yard site in Harmondsworth following an eight week program of works. Following detailed site characterisation works, we devised a remedial strategy comprising the targeted excavation of contaminated soils using GPS surveying equipment. Contamination issues included soils impacted with lead, hydrocarbons and solvents and additional impact of underlying groundwater. We pre-treated excavated soils on site, with over 100tonnes of material reclaimed for re-use on site.

Over 500tonnes of soil required offsite disposal to recycling facilities and an additional 30tonnes of plastic waste and 8tonnes of metal were recovered. Groundwater was treated with in-situ oxygen release compounds. Following remedial works we have completed detailed landscaping of the site, importing over 800tonnes of top soil and foundation materials, meeting the Client’s requirements to return the site to public open space. The site will shortly form part of the larger Harmondsworth Moor parkland complex.

Contract Value: £100-250k