Earthworks Design and Control
Designing earthworks for various sized schemes under a variety of ground conditions is a significant CGL capability, along with ensuring earthworks are implemented under proper construction control.
We can develop an effective earthworks strategy as part of a larger enabling works package that addresses remediation planning and regulatory issues to deliver a build-ready development platform for our clients, allowing follow-on contractors to continue as normal. Our senior staff have substantial experience in the design of major earthworks schemes including highways and rail schemes, landfill reprofiling and redevelopment, plus large mass balance exercises. Many of these have necessitated detailed engineering analysis to overcome difficult ground conditions and ensure long term stability and serviceability.
Our capabilities include production of earthworks specifications, assessment of sources to identify material suitability, the effective reuse of materials and minimisation of the cost of imported fill. Our approach uses the principle of ‘relationship testing’ where complex engineering parameters can be correlated to routine test procedures on site. This simplified but robust approach to compliance testing results in confidence in the construction and savings in earthworks programmes.
CGL specialises in the design of earthworks over soft alluvial soils and in the design of ground improvement methods to enhance settlement rates. Typically these permit settlements that would take 12 or 18 months under normal conditions to be completed in as little as 3 to 6 months, substantially reducing construction programmes and associated costs.
In addition, careful design of earthworks with geotextile reinforcement can lead to the creation of near vertical walls and development platforms that can allow highly constrained sites to become developable. We have been involved in a number of schemes in which levelling of sloping sites has been recommended to allow the construction of residential development. Similarly, the judicious use of test data and detailed specifications can be used to allow placed fill to support structural foundations.
Where earthworks necessitate the removal of contaminated materials, CGL’s in-house waste advisors are able to refine disposal classifications that substantially reduce off-site disposal costs. Our work often leads to substantial savings which make marginal schemes become financially viable. An example of this is our recent involvement with the Wandsworth project. Clients often seek our independent advice during early tender evaluation to enhance their competitive position and, ultimately, their success rate.
Supporting our design, we provide construction quality assurance services to monitor and validate the formation of different types of earthworks ranging from simple capping layers and reprofiled site, to large reinforced earth structures. This independent validation and certification offers confidence to clients that their asset conforms to the relevant design codes, providing posterity for the future.