Cost-Effective Inert Reinforced Soil Solutions

Tensar are providing cost-effective, inert reinforced soil solutions for Stockton Road Link.

As part of the Government's 10 year transport plan, the construction of the new £17m South Stockton link road required retaining walls and a steep soil slope.

Main contractor Birse Civils Limited, working on behalf of Stockton-on-Tees Borough Council, considered traditional concrete solutions, but used the Tensar Wall System as a cost and time saving aesthetic alternative.

Tensar geogrids were also used to reinforce a stabilised slope in highly aggressive soil conditions.

Two low retaining walls were required, one of which was to carry the newly constructed dual carriageway which provides local access to the national trunk road system.

The BBA certified Tensar Wall System (TWS) was selected over conventional reinforced concrete retaining structures, as there was no requirement for a formal foundation, thereby easing workflow constraints.

In addition to these cost and time saving benefits, an aesthetic finish could be selected for the walls - in this case a dry laid, split face sandstone coloured block.

Where an access corridor was required at the toe of the embankment, a reinforced soil slope was constructed, with a maximum height of 5.5 metres, and a face angle of 45deg.

The lightweight PFA fill, which had been used in the structure due to the underlying soft ground, had high alkalinity and would have adversely affected the integrity of many geosynthetic reinforcement materials.

Use of Tensar uniaxial geogrids was possible because they are manufactured from high density polyethylene, which is exceptionally inert, and highly resistant to chemical attack including high pH values.

Due to the relatively shallow face angle of the reinforced soil slope, the Tensar solution allowed a formal structural facing to be omitted; the geogrids were simply placed in horizontal layers onto compacted fill and terminated at the slope face.

To provide long term erosion protection, Tensar Mat, a three-dimensional cuspated net was placed over the face of the slope in conjunction with the topsoiling operation.

Design and build contractor: Birse Civils Ltd.

Consultant engineer: Arup Client: Stockton-on-Tees Borough Council.

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