Challenge

GeoGrow was approached to design and install two Rootlok® earth reinforced retaining walls for two attenuation ponds for Tonic Construction on a new Bloor Homes development in Faringdon, Oxfordshire.

The retaining walls were installed early in the contract enabling the roads and sewers to be completed quickly to allow surface water to drain directly into the attenuation ponds.

Solution

The larger of the walls, approximately 2.5m high, was built with extended geogrids and a backfill length of 3m due to poor ground conditions. The wall was designed as a tie-back build incorporating Stratagrid BBA-certified geogrids using quarried Type 1 stone, which is compacted at every bag level. Geogrids are installed at every third bag level (420mm intervals). A roller and HD wacker plate was used to compact the stone in accordance with Table 6/4 of the MCDHW specification for highway works. Pipe sleeves were installed during the wall build so that the fencing contractor could install fence posts easier and not disrupt the walls backfill during the fence installation.

The second wall had no loading parameters at 1.2m high and was designed as a standard tie-back build with a small, compacted stone backfill area of approximately 1m.

Both walls were hydroseeded on completion with a low-maintenance grass seed mix in May and, by the end of the summer, the walls had a good coverage of grasses.

Outcome

The client, Tonic Construction and the Rootlok™ in-house installation team were very happy with the quick install and sustainable green finish.