Feature sponsored by Flow, level & control
of England, by a partnership involving a water company, a contractor, an instrumentation provider and an inspection company. The flow monitor at Fowey WwTW needed to be replaced as part of a capital maintenance programme which was challenging due to the constrained nature of the site. Therefore, more innovative solutions were considered as an alternative to a like-for-like replacement. Engineers from Tecker, a MEICA contractor for South West Water, therefore reviewed the available options. “The channel is in-between two aeration ditches, and there was insufficient room to extend or divert the channel,” explains Tecker project engineer Ben Finney. “We therefore considered repairing or replacing the flume, but an alternative suggestion was made that we contact Nivus to see if their cross- correlation flow meter might be able to deliver accurate flow measurements without the costs and problems associated with capital works.”
S BACKGROUND
Accurate wastewater flow measurement enables the managers of treatment plants to operate efficiently – optimising treatment, minimising costs and protecting the environment. Consequently, through MCERTS, the Environment Agency places strict performance requirements on flow monitoring devices and structures at WwTWs in England. The MCERTS performance standard establishes the minimum requirements for the self-monitoring of flow. The MCERTS standard applies where a site has a permit under the Environmental Permitting Regulations (EPR) requiring the process operator to monitor liquid flow of sewage or trade effluent, and to collect and record the results. MCERTS specifies the minimum requirements for self-monitoring of flow where operators have installed meters to conform to the Environment Agency’s permit requirements. Natural Resources Wales permits may also specify that flow monitoring systems are certified against MCERTS. Regulated flow measurement systems and structures are usually inspected annually, and non-compliance can be triggered by a number of factors such as ageing and eroded channels, or a failure to deliver the requisite levels of accuracy due to changing flow volumes. For example, growth in the local population combined with increasing rainfall intensity due to climate change, can result in flow structures ‘drowning out’.
FLOW MONITORING AT FOWEY WWTW Following Tecker’s request, engineers from Nivus visited the site and specified the instrumentation requirements, based on the Nivus NF750
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mall wastewater treatment works (WwTWs) frequently present significant physical challenges for instrumentation and control engineers. However, a compliant flow measurement facility has been installed at a plant in Fowey, in the south-west
ENSURING FLOW COMPLIANCE AT FOWEY SEWAGE WORKS
October 2024 Instrumentation Monthly
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