Sainsbury's unveiled plans in 2011 to build a 500,000 square foot distribution centre near Exeter airport, to initially serve 35 stores in the South West, including Devon and Cornwall. The proposed development represented the first phase in the long-awaited Intermodal Freight Facility, now known as Exeter Gateway, which forms part of the East Devon Growth Point.

The site is split into two, with differences in levels of up to 6.25m, so a retaining structure was required along a length of 180m to retain the car parking area above with the distribution centre below.

Solution

When Buckingham Group contacted Phi Group, the Permacrib Timber Crib solution was suggested as the most cost effective and buildable solution. Of particular importance was speed of construction and cost. With a face area of nearly 1,000m2, Phi Group constructed the Permacrib wall in 5 weeks, using two gangs to shorten the programme.

As Buckingham Group was undertaking a large muck shift operation, they wanted to re-use the excavated sand as the backfill material to the rear of the Permacrib retaining wall.

In conjunction with additional testing carried out by Buckingham Group, Phi Group also carried out compaction testing throughout the backfilling operation to make sure the material was suitably placed and compacted. The sand material also became denser as levels were reduced.

Buckingham Group asked if the excavation could be steeper than the 60 degree profile specified within Phi Group’s original design. Phi Group re-designed the Permacrib wall based on retaining in situ soils and enabled the temporary earthworks to be excavated at 76 degrees where the material allowed, therefore saving on excavation and any possible muck-away.

Outcome and benefits

The Permacrib Timber Crib retaining wall was completed on time and on budget.

As a specialist contractor, Phi Group’s wide range of solutions means that they can adapt to any specific site requirements. Phi Group offers a full design, supply and construction service with responsibility resting in one place. This gives clients and contractors peace of mind and one point of contact for the retaining structures on their project.