Case studies

North Wales SPS / STS Flow Monitoring Scheme

Design Works

In order to install flow monitoring equipment at the 19 sewage pumping stations the type and size of instrumentation had to be determined, this was done by flow and load calculations and known details for each pumping station.

Dependant on the results from the flow survey and the instruments suitability for the application the instrument was chosen. The range of instruments used were; a 'Time of Flight' device (Siemens FST020) a 'Rate of Change' device (Pulsar Quantem2) or an in-line electro-magnetic device ( Siemens MAG5100w).

Each pumping station had different power supply characteristics and the instrumentation supply had to be calculated individually using a preparatory design package (Amtec).

All of the design works were in compliance with current Health & Safety regulations and best practice, IEE wiring regulations BS7671, WIMMES, DCWW Specifications and Standards with particular attention to the following; MS101, MS103, ES101, ES319, CS501 and PS203.

Health & Safety

This scheme was not notified to the HSE, no F10 was posted and the scheme was carried out without a principal contractor, however The scheme was safely managed in accordance with Celtic process Controls Health & Safety management system and was in compliance with DCWW Management of Contractors system. Specialist training was required for the scheme which included Confined Space training.

Civil Works

Minor civil works were required at several sewage pumping stations in order to install the flow monitoring equipment, this included the installation of cable ducts, the excavation of trenches, core drilling of chamber walls, core drilling of well covers and the making good of broken grounds and chamber walls.

Mechanical Works

The use of ultrasonic clamp-on flow meters and rate of change controllers reduced the need to isolate and cut into existing pipework, at several sewage pumping stations this was not practical and in-line flow meters were required, the existing galvanised pipe work was isolated, removed and modified to incorporate the flow monitoring device.


The instrumentation for this project was specified by Celtic Process Control in the design phase then ordered by DCWW and free issued for installation. Installation of the devices was challenging because of the diversity of application, this was overcome by -in-depth training for each device and for the application that it was to be used for. The instruments were located outside any hazardous areas with only intrinsically safe sensors being installed in any chambers or wet wells. All instruments were commissioned, calibrated and set up onto DCWW telemetry system to enable full trended flow data to be collated.

Electrical Works

Power and signal cabling was installed complete with suitable containment to meet the diverse needs of the individual pumping station as the control buildings ranged from a small roadside kiosk to large self-contained pumping stations. Each station had to be installed differently.

All the power and signal cables were sized according to load / length calculations with suitable protection installed.

The majority of the sewage pumping stations are of an old build and do not meet the current IIE Regs: BS7671 or / and DCWW standards.

The majority of the pumping stations were installed with new 230v - 110v transformers, new 110v instrument distribution boards bringing them closer to current standards.


A full document package was produced for each pumping station containing the following documents;

  • NICEIC electrical test certificates
  • Block Cable Drawings
  • Instrument Loop Drawings
  • Instrument Calibration Certificates
  • Manufacturers Inspection / Test / Calibration Certificates
  • Hydraulic Test Certificates (where pipe work was installed)

Similar Schemes

This project was carried on throughout the whole of Wales covering all the geographical regions;

South West Wales 12 Sewage Pumping Stations

Swansea catchment 10 Sewage Pumping Stations

Hereford catchment 12 Sewage Pumping Stations

South East Wales 10 Sewage Pumping Stations

Discipline : Civil

% split : 16

In House - % split : 100

Sub-Contracted - % split : 15

Discipline : Mechanical

% split : 31

In House - % split : 100

Sub-Contracted - % split : 15

Discipline : Electrical & Instrumentation

% split : 53

In House - % split : 100

Sub-Contracted - % split : 15

Case Study Information
North Wales
Start Date:
4 weeks
Form of contract:
NEC3 Short Form - Option A
Contract status:
Contract title:
Flow Monitoring at SPS/STS
Contract value:

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