The Challenge:

The original scheme design included construction of approximately 330m of clay-cored flood banks. This would have involved importing around two thousand tonnes of clay, and three thousand tonnes of primary (virgin) aggregates to use as a fill material.

Using the CEEQUAL process, which is the evidence-based sustainability assessment, rating and awards scheme for civil engineering, infrastructure, landscaping and public realm projects, as guidance, and noting that the distance to suitable material sources meant that works would be associated with significant HGV movements with associated air quality and carbon impacts.

It was therefore decided that a more sustainable solution was required.

The Solution:

Kier’s early contractor involvement enabled a change to the bank design and specification, removing the requirement for a clay core, and allowing for the bank to be built from a single cohesive material.

Using the cohesive fill material, Kier Professional Services (KPS) produced a revised design, establishing the structural properties and incorporating layers of geotextile to reinforce the bank. Approximately 5000t of material was required and, through extensive research, a source was found at a local development site, where excavated material was waiting for disposal. Extensive testing was undertaken and soils from this single site were selected as suitable for the works required.

Early engagement with the Environmental Agency Waste Team and CL:AIRE was required to ensure compliance with the necessary legislation. The earlier this engagement is carried out, the smoother the overall process will be. Thus, soils were imported to Helston under a CL:AIRE MMP established in collaboration with the developer.

The Impact:

This revised process enabled use of soils in the flood banks as a material rather than a waste requiring disposal from the original development site where they were excavated.

In addition to cost savings to our client in excess of £100,000, the use of locally sourced soils at Helston resulted in a reduction of approximately 25,200 HGV miles and associated carbon savings of 20t. There was also a reduction in carbon associated with the original requirement to use primary aggregates of 18t.

Added social value was provided through collaboration with the local developer who saved significant costs by avoiding the requirement to dispose of soils.

Our collaborative relationship with our client and designer in early construction stages enabled the review and subsequent change in specifications to deliver improved environmental and social sustainability outcomes and reduced project costs. The importance of local knowledge and development of working partnerships with other contractors was also critical in delivering these benefits.

While CEEQUAL can help influence sustainable solutions, it is important to involve wider EA teams to aid the CL:AIRE process from an early stage. This has clear benefits to the environment and both the Environment Agency and developer projects should be considered for similar projects where importing large quantities of soil is required. 

" Through early review of the Helston project, Kier were able to identify an opportunity to influence the flood bank design and successfully source local material. This has positively contributed to the projects carbon and efficiency targets. A good example of the CEEQUAL and CL:AIRE processes, to be considered for similar projects. "
Becky Richards Project Manager Environment Agency

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