Water & Wastewater Asia January/February 2024

FOCUS
Mine water treatment
relies on borehole loggers
1
For the last 9 years, Severn Trent
Services has managed a contract
for mine water treatment across
the Coal Authority estate, including
73 mine water treatment schemes
in England, Scotland and Wales,
the UK. These schemes take
the form of three types: passive,
pumped-passive and active. Water
levels are one of the elements
monitored at these sites, which
have approximately 600 monitoring
points. The majority of the readings
are obtained manually with dip tapes,
and by utilising loggers, around 125
of which are OTT ecoLog water level
loggers.
At most sites, mine water is pumped
to a treatment facility which
employs oxygenation, filtration and
sedimentation to raise the quality
of the water in compliance with
discharge consents. “Mine water
from legacy coal mines is treated
at many of these sites utilising
settlement lagoons and reed beds,”
said Oren Environmental data and
reporting manager Paul Robinson.
He added that the management of
these resources is dependent on
reliable data including water level
measurements, which they have
been using OTT instruments since
2016. With the benefit of water level
data, the flow of water through the
lagoons and reedbeds is ensured
to maximise treatment before water
is discharged to watercourse,
according to Robinson.
“One of the capabilities of the
loggers is to create alarms and we
are investigating for future use,” he
said. “In addition to the older ecoLog
500 and the newer ecoLog 1000,
we also utilise five ecoLog 800 to
collect and monitor conductivity
measurements. Conductivity data
can be used to assess the quality of
water by identifying minerals that are
present in the water.”
Where the ecoLogs are deployed
in surface water weirs, the level
measurements are translated into
flow, which informs the management
of the treatment process. Many of
the original water level loggers were
ecoLog 500 devices, some of which
are still in operation. However, these
are being gradually replaced by
ecoLog 1000 instruments. Robinson
said that the ecoLog 1000 has
an advantageous feature. “Data
from the older units was collected
Water & Wastewater Asia | January-February 2024 41