ME Case Study Two

Inlet Works & Upgrade

Meadowhead Inlet Works

Meadowhead Inlet Works receives the from the Irvine Valley Sewerage Scheme for preliminary treatment. Gravity flows are received at Meadowhead from the Irvine Valley Sewer (approx.1000l/s) and from the local Caledonian Paper Plant (278l/s). The remainder of the flows received at Meadowhead is pumped from satellite pumping stations. WGM Engineering carried out large MEICA refurbishment engineering works at Meadowhead sewage treatment works (STW) which involved the mechanical and electrical replacement of critical equipment, with semi-automaticheavy involvement of ICA upgrade and modification work.

The inlet works refurbishment involved extensive ICA architecture modification and extension work, including instrumentation, hardware and software engineering. This included:

  • Extension of existing hardwired network for the inclusion of new I/O from remote LCP’s

  • Addition of new Profibus and fibre optic networks to the existing Siemens S7 PLC for the inclusion of the remote MCC

  • Managing the installation of new hardware and instrumentation to the existing ICA section including panel mounted level controllers, optical link modules, PLC Modbus card, input cards and marshalling sections

  • Carrying out fibre optic and Profibus testing of new networks

Meadowhead Inlet Works

The hardware installation and modification work was carried out in a phased manner allowing for all offline installation work to be installed and checked before completing the intrusive connection elements. Temporary work arrangements were put in place for final connections, allowing for the plant to be manually controlled, operated and maintained during this period. Upon completion of the ICA tie-in, the PLC functionality was restored, returning the site to automatic operation and allowing equipment testing to be carried out on an individual basis to suit the commissioning plan.

Changes to the existing control architecture associated with 8No grit pumps and 2No grit rakes were made following the replacement of the field equipment and upgrade of upstream plant. This element of the works was previously operational on a semi-automatic function, with the grit pumps operating for a hardwired time clock period and the grit rakes set to operate 24 hours a day. This was updated for automatic functionality involving on inlet channel flows, grit detector levels and grit rake condition, including run on timers and separate storm flow conditions.

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