Civil Engineering

Roads

Cognition carries out a number of road construction projects per year as part of remediation works or stand alone contracts. We have recently completed a road scheme for Balfour Beatty in Guildford including deep drainage, curbing, beany blocks, ground improvements to an old landfill, tarmac white lining and street lighting and furniture. Another interesting roadworks project completed recently was relocating a coach park for the O2 in Greenwich which included all of the aspects of the Guildford project with additional diversion of services and concrete retaining walls.

Where possible we look at redesigning as much of the schemes to make them more sustainable.

Drainage

Cognition employees its own drainage gangs and carries out and large number of drainage schemes per year whether it be concrete, clay or plastic pipes, shallow and deep drainage. Some of the schemes undertaken in the last year included pipe jacking under a duel carriageway in Wandsworth in three 600mm diameter pipes under the water table over 6 metres deep. We have also recently completed a new drainage scheme in Newbury town centre.

concrete structures

Cognition carry out a wide variety of concrete works from capping beams, foundations, lift shafts, concrete frame buildings and tunnel shafts. We are currently working on a 21-metre-deep tunnel shaft as part of the largest board tunnel in Europe. This involves 24-hour day working. We have also recently completed a tunnel shaft in Wandsworth, and an 8 story concrete frame building in Newbury which finished 5 months ahead of programme.

Though some of our works are standard civil engineering concrete structures we enjoy working on more complex and difficult structures that most people would shy away from. We have a highly motivated, experienced workforce combined with strong technical support from the management team who have years of experience.

Stabilisation and piling mats

Cognition carries out soil stabilisation to improve the geotechnical strength of soil materials. The process often involves carrying out trials to select an appropriate binder such as cement or lime and optimising the binder concentration to achieve the required strength. Cognition pioneered the application of stabilisation for installation of piling mats. We also use this process to improve subgrade or replace subbase for roads and hard standings. Stabilisation enables the re-use of significant volumes of site soil materials that might otherwise be disposed off-site to landfill. The stabilised materials have increased strength compared to traditional granular fills and stabilised subbase can negate the need for subbase drainage. An additional advantage of stabilisation is that it can encapsulate soil bound contaminants making them less able to leach into groundwater.

Slope Stability

Cognition can carry out stability assessments as well as design and install geotechnical solutions to improve slope stability including stabilisation and reinforcement, vegetative walls and gabion baskets.

Surcharge and land settlement

Cognition has designed and delivered a number of site improvement schemes by preloading and surcharging soil prior to development. This type of solution is beneficial where a site is poorly compacted or at risk of differential settlement due to varied soil materials within made ground. These schemes often benefit from the installation of vertical band drains and drainage blankets to relieve ground pressure across a site which occurs during surcharging to aid soil consolidation.

Dynamic Compaction

Cognition uses state of the art dynamic compacting rollers which are capable of compacting soils to depths of 4-5m. These techniques offer rapid solutions for construction sites. As well as being able to focus compactive effort at different depths, the roller can identify soft spots and record soil density across the soil profile.

Earthworks

Cognition carry out a large number of earthworks projects involving heavy cut and fill. We move approximately 2 million cubic metres per year. As part of these works there is often a huge volume of geotechnical testing, carried out to demonstrate the fill is done correctly and will not pose a risk for long term settlement.

For many years, due to its adverse impact on resources, carbon, the environment and sustainability, material excavation and disposal (“Dig and Dump”) is considered unacceptable practice. Limited landfill capacity, increasing landfill tax, new and emerging remediation technologies, public perception, and an unwillingness to simply move contamination from one place to another are further reasons why the construction industry is rapidly moving away from this out-dated approach to soil management. 

At Cognition Land and Water, our aim is to recycle 95% of all excavated materials to minimise waste generation and disposal, adopt a more sustainable approach, and comply with our net zero carbon commitments. An example of this in practice is the work undertaken at Klondyke on the Isle of Sheppey. Here, we excavated, processed and treated contaminated soils, only removing untreatable deleterious waste to landfill. We also imported clean, naturally occurring soils from other local sites to raise the development platform out of the flood plain, thereby diverting these soils from landfill also. All of this work was done under a combined Deposit for Recover Environmental Permit and DoWCoP Materials Management Plan.

 Similarly, our decommissioning works at Harwell, the largest nuclear decommissioning and delicensing project in the UK, proved to be a huge success. Soil excavation was initially directed by an excavator bucket-mounted radiation detector - this meant that only impacted soils were excavated in the first place. Impacted soils were then excavated and placed into specialist 1m3 bulk bags under the strictest health and safety controls. These bags were assayed onsite to determine the level of radioactivity in the soils, thereby allowing waste streams to be segregated and ensure that only radiologically contaminated material was taken to nuclear waste facilities.