From initial enquiry to installation in less than five weeks.

That was the fast-track story of the installation by the Morrison Consent Compliance Team (MCCT) of a new caustic dosing system and utilisation tank at Southern Water’s Ashford Wastewater Treatment and Recycling Centre in Kent.

Morrison lead project engineer Andy Jenkins explains: “All consent compliance issues are urgent, and once Morrison was given the job, we put the design and construction work to Gee & Company, who we knew would respond quickly as they manufacture the tanks in their own plastics fabrications plant.”

Critical levels

What was driving the initiative from a compliance point of view was that Southern Water envisaged that ammonia levels could creep towards critical levels in cool weather.

The existing system was at the end of its useful life, which led the decision to replace it with an entirely new chemical storage tank and dosing pumps.

Following discussion with the client, the design parameters of the system were agreed.

The brief called for a tank storage capacity of 35,000 litres of sodium hydroxide, and a system capability to handle the present 25% caustic concentration, but with a design contingency to store and dose the next level of specific gravity – 37%.

Gee designed the new tank and manufactured it from Celmar GRP to the standards required BS4994 category 1.

They also supplied a fabricated bund and rain skirt, together with a galvanised mild steel access ladder and platform. In addition, all associated instrumentation including the fill-point panel were sourced from Gee, who also used new dosing pumps with built-in electronics from the Signal series 200 range.

Everything was delivered to the Morrison Consent Compliance Team at Southern Water’s Ashford site, installed, tested and commissioned in less than five weeks – a considerable feat in any circumstances.

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