Dormer Construction

Box Culvert Underpass

PROJECT START October 2014
COMPLETION January 2015

This contract was for the installation of a 3mx2m x22m long cattle underpassĀ  and 40m wide and 22m long approach race, under a public road crossing. Site conditions involved a high water table, alluvial shingle, and artesian water pressures. In managing the site conditions, particularly the water table and soil type, Dormer installed global dewatering around the whole site, then sheet piled half of the road crossing at a time, then repeated the sheet piling process for the other half of the road crossing. 11KV overhead power lines hazard, within the work zone, was managed and controlled to eliminate risk of injury.

To achieve watertight solutions, the underpass section was wrapped on Volclay Voltex and Swelltite and the approach races had either hydrophilic seal strip or Rearguard Waterbar installed at each construction joint . In addition to all the waterproofing there was also anti-flotation beams poured to the structure to stop it from floating.