Emergency flood prevention in Bollington, Cheshire
Following extreme water levels in the River Dean in Bollington, a temporary wall needed to be installed to enable a dilapidated one to be dismantled and replaced after suffering a partial collapse. The emergency work was required to protect the properties and road infrastructure immediately adjacent to the river.
The Project
A temporary wall needed to be installed to enable 22 metres of dangerous, damaged wall to be dismantled and replaced. The wall required three rows of small-diameter micropiles to retain the land near to domestic properties and roads. There was a high risk of further flooding and subsequent damage to what was left of the existing retaining wall.
The Solution
The micropile design was a buttressed, cantilevered wall incorporating a total of 143 mm micropiles. Using a lightweight sonic drill rig, we installed three rows of micropiles at depths of up to nine metres for the outer piles and up to seven metres for the inner row of piles. Thick wall hollow bars of 50 mm diameter were installed with a bit diameter of 130 mm.
Site batched grout was used from our colloidal mixer pumps. Neat cement grout was injected through the hollow bar or drill bit in a carefully controlled way to avoid any loss into the river.