One of many projects successfully delivered for the States of Guernsey over the past 20 years, this turnkey project combined our Process, Water Engineering and Controls expertise. The scheme was not only logistically challenging due to its island location but also as it was completed ‘airside’ within the operational constraints of an international airport.
Full turnkey delivery of an innovative ground water treatment plant designed to remove the contaminate ‘Perfluorooctane Sulfonate’ (PFOS) from a stream running from Guernsey Airport and eventually discharging into the local reservoir. Detailed Design and Commissioning of the Process Plant & Equipment was completed by our in-house specialist design and commissioning teams.
A diversion chamber and 7m deep pumping station provide a design flow of 20 l/s to the process plant duty/standby anthracite pressure filters. These remove solids from the ground water and protect the GAC filters from fouling. Flow then passes through four GAC filters installed in two parallel trains each filtering 10l/s, with a 45 minute contact time ensuring that the PFOS is removed. The filtered water gravitates back down the return pipeline to the downstream side of the diversion chamber. The backwash system which cleans the pressure & GAC filters is called to run by time or differential pressure. Storage tanks with a combined capacity of 190 m³ provide storage of raw, filtered, waste and filtered waste water are served by cPVC process pipework .
Our in-house panel division designed, assembled and programmed a Form 4 MCC, including starters for 11 pumps with starting methods including VFD, SS and DOL. A treatment control panel was fitted with a Siemens PLC and state-of-the-art touchscreen HMI to interpret the process signals and control the 96 electrically actuated valves, pumps, and systems required to run the process.
A perimeter palisade fence provides security and the process plant is situated within a 32 x 16m bunded Reinforced Concrete slab to ensure any spillages are contained.