Tensartech Earth Retaining system speeds Burnley College's construction and reduces costs of materials

Savings in time, materials, cost and labour have been achieved by Shepherd in the construction of Burnley’s £81million Further and Higher Education College by choosing reinforced soil technology over conventional reinforced concrete retaining walls, or gabions.

Tensartech Earth Retaining systems were employed in both the creation of the new entrance on a steep slope and rebuilding the river wall boundary. The Tensartech solution was specified because of its low environmental impact and aesthetics, with Tensar’s TW1 modular block wall finish specially chosen to complement the college’s local architecture.

“The original proposal for the tiered walls of the college entrance was for reinforced concrete at up to 750mm thick,” commented David Houghton, Shepherd Construction Senior Planner.

“We had used the Tensartech solution on previous brownfield projects and thought it would be ideal to speed construction and reduce costs of materials, as well as providing a very acceptable finish. At Burnley, the TW1 split face, modular concrete blocks were supplied in Yorkstone colour to complement the rest of the buildings.

“We were able to use Tensartech solutions to substitute for at least 75% of the reinforced concrete construction that was originally proposed for the project. Construction with Tensar’s uniaxial geogrid secured to the dry laid modular block construction saved about 30% of the time it would have taken to install formwork, steel reinforcement and pour the concrete. We used reclaimed fill from a local site rather than expensive imported aggregate, further reducing cost and environmental impact.

“However, the real bonus of the Tensartech solution is that we could continue with the construction of the pavement layers immediately without waiting for the concrete to gain strength. Dry laid blocks mean there is no waiting for mortar to dry and we did not have to finish off in-situ concrete to the required aesthetic standard for the project either. This probably saved us a couple of weeks, and is a great help in completing the project for the September 2009 opening date.”

For the river wall construction, the Tensartech solutions were installed by contractors Adana Construction to replace the original river wall which had been part of the basement of industrial buildings previously on the site. Instead of a proposed gabion solution, Adana were able to save significant time and cost in building a 5 metre high retained earth structure. Once again, Tensar’s uniaxial geogrids were secured using polymer connectors to the TW1 split-faced, concrete modular block face, with local reclaimed backfill, created an attractive and robust boundary wall very rapidly.