Shortlisted entrants for this category had to demonstrat an innovative, unusual, or cutting edge approach to environmental and sustainability issues on a geotechnical project.
This could be in the form of reuse of materials or existing structures/foundations, innovation in redeveloping brownfield sites or use of technology/design to reduce carbon emissions or any initiative that drives sustainability across the wider project.
Aarsleff Ground Engineering
Driven Precast Piles
aarsleff precast piles
Aarsleff suggested a driven precast concrete piling solution to provide quick and efficient foundations for a new wind turbine in Hull for a major food company, which wanted to reduce its own plant’s energy bill and carbon footprint.
The precast piles comprising of recycled reinforced steel use 10% less concrete and 5% less steel than cast-in-situ vertical piles as well as keeping the surrounding ground intact so that there is no need to transport excavated material away. The piles can be installed continuously, unlike in situ piles, where the process involves missing out intermediate piles to allow the ground to recover and needs extra time for concrete to cure.
Housedeck is a versatile design and build foundation and ground floor slab system for new residential buildings. The bespoke system can be supported on piles or treated ground and uses several patented elements to reduce wastage and improve the safety and efficiency of foundation and ground floor construction.
Its benefits include reduction in the amount of concrete, reinforcement, single use timber shuttering and temporary works needed. The system also reduced the volumes of material exported as a result of less excavation to create a level platform and minimises material imported through use of thinner working platforms.
In the best ground conditions with relatively shallow trenchfill foundations, Housedeck provides a 12% reduction in embodied carbon. In the “worst” ground conditions that trenchfill foundations could practically be used for, it provides a 45% reduction.
The Wash Plant
Complete Utilities it is unusual compared to its peers in that it has commissioned a dedicated processing plant to recycle 100% of its trenching waste to produce a type 1 aggregate material complying with highways specifications.
The main element of the processing plant is a Powerscreen Aggwash, which washes and grades the trench from spoil the company generates in its utility work. The Aggwash system uses magnets to remove ferrous metals and a trash screen “floats” off other contaminates. A log washer, a set of screens and sand tower produces a series of graded aggregates.
Enhanced DNAPL coal tar extraction and encapsulation
Significant cost and programme savings and reduction in environmental disruption was delivered through use of Geobear’s injected expanding geopolymer resin to stabilise gas holder contents. In addtion to stabilisation, the technique simultaneously displaced coal tar towards the existing extraction wells and encapsulated any coal tar left-in-situ.
The expansion of the resin either displaces trapped coal tar or encapsulates it and, once cured, the resin provdes geotechnical stability to the holder fill and reduces future environmental risk.
Careful design of the injection sequence allows the coal tar to be displaced towards the existing extraction wells from where it would be removed by suction for disposal without impacting on the surrounding environment.
Ground Stiffness Surveys
Advanced Continuous Surface Wave (ACSW) Testing System
The ACSW system allows accurate bulk measurement of in-situ ground stiffness to be obtained rapidly, reliably and non-intrusively.
The system, which was designed and is UK manufactured by the firm, uses a small portable shaker to generate surface waves over a range of frequencies, the speed of which is measured by a short array of six geophones. An integrated software package generates on-site and post-testing ground stiffness profiles.
Operated from a 4WD vehicle without the need for heavy plant, the system generates minimal amounts of waste and provides an alternative to less-sustainable investigation techniques such as large-scale load tests or intrusive investigation.
Thames Tideway - Kirtling Street - contaminated material treatment
Contracted by FLO JV to remove and treat contaminated material from the seven shaft sites for Thames Tideway, Keltbray Environmental used barges to transport 22,000t of hazardous and non-hazardous soils and concrete excavated from Kirtling Street site to their east London facilities.
The contaminated material was unloaded, analysed and underwent a treatment processes to remove recyclable components and contaminants. The material was then barged to restoration facilities and used in the creation of new landforms and as a capping material.
The process meant that all the contaminated material produced at the Kirtling Street site did not go to landfill and removed 1,200 lorry journeys off London’s roads.
Ramboll was appointed to design 1.8ha of reedbeds for part the 211ha Walthamstow Wetlands scheme - the largest urban wetland nature reserve in Europe. Focusing on three reservoirs, Ramboll used dredged sediment from water treatment works settlement lagoons to form beds that were planted to create new reedbed habitat.
The beds were retained using geotextile engineered structures held up with timber posts. The design allowed for flexibility in changes in water depth and ground conditions, with the “king post” structure modified by decreasing the spacing of the posts and by tying back the posts to an additional line of anchor posts.