The City of Parksville has received inquires regarding “clay banks” along the Englishman River, and if they’re a cause for concern.
A release issued by Parksville’s manager of communications, on behalf of the Englishman River Water Service (ERWS), aims to provide information on the natural occurring wall of clay behind properties on Kaye Road in the Rivers Edge subdivision located in the Regional District of Nanaimo.
Groundwater flows out of the bank causing pieces of the bank to become unstable and fall into the river; this turns the river grey until the water washes it away. Prior to construction, significant study and testing was undertaken to determine if clay bank failure would be an issue. It was determined debris from the clay banks does not pose a threat to the ERWS treated water. Part of the water treatment plant testing included proof piloting on the ultra filtration membranes by running samples of the water containing the clay, removed without issue.
During testing, clay bank turbidity and colour were analyzed and during plant construction, measures put into place to offset any clay bank failures and thereby ensure the purity of water coming from the plant.
In February, there was significant sloughing of the clay banks. Data verified any particles which could be harmful were removed from the water during the treatment process. The clay particles are small and pass through the sand separator and strainers but because they are too large to pass through the fibers of the membrane filtration system, are washed off during the backwash cycle and removed. During a clay bank event, the situation is carefully monitored, and any adjustments are made.
The Englishman River water treatment plant which began testing in 2019, commissioned in January 2020, is equipped with many operating safeguards in place to protect the integrity of the drinking water supply for the City of Parksville and the Nanoose Bay Peninsula water service area.
– NEWS Staff, submitted