WorkDry_ESG Report_FinalDigital_Aug 2025 - Flipbook - Page 54
CASE STUDY
INTERNATIONAL
RISK MANAGEMENT
on the River Bewl
While Knights Brown were completing civil engineering works next to the River
Bewl, groundwater and rain from recent storms caused flooding on site. We were
tasked with pumping the excess water off site, through a filtration system and
discharging it into the adjacent River Bewl. A perfect opportunity for a combined
Selwood & Siltbuster solution.
The challenge was that the water needed to be treated to a high enough quality
before being discharged; the pumps and the treatment area couldn’t take up
too much space on site; the system had to run 24/7; and required a flow rate of
40m³/hour into the Siltbuster settlement tank.
Our solution was to install a Selwood Sulzer XJ40MT pump that delivered flows
into the settlement tank. It ran on floats for automatic 24/7 operation, and was
controlled by a 15kW variable speed drive (VSD), allowing for adjustments to
match the required flow rate, and a magnetic flow meter. Siltbuster installed its
HB40 settlement tank and a mix tank.
In the settlement tank the coagulant modified the surface charge of slowsettling particles, enabling them to form pin-flocs. The flocculant then bound
the pin-flocs into larger flocs, which settled under gravity. The mix tank enabled
homogenous chemical dosing; and once treated was discharged into the river.
This resulted in a cost-effective, carbon and fuel-saving solution to manage the
water egress without disrupting site work; treated water posed no environmental
impact upon discharge; the pumping and treatment setup required minimal
space; and no changes were needed to the construction schedule.
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