VIDEO: SAF wastewater solution helps UK ‘garden city’ expansion

CASTLE Hill, UK - The first phase of the government's new garden city, Ebbsfleet, to be built in Kent will have a specialised wastewatertreatment plant built by WPL.

The new town of Ebbsfleet is one of the most important developments in the south of England, with plans to build 15,000 new homes for a planned population of 40,000.

Multi-utility provider Metropolitan was awarded the contract to deliver services for the 1,500-home Castle Hill development by Landsec. The agreement includes installation of a new onsite wastewater treatment works for 4,000 population equivalent (PE).

Metropolitan appointed Alpheus, a specialist in water and wastewater asset management and design, to provide the plant.

The new wastewater treatment works is being built in two stages and WPL is supplying a total of 16 above ground WPL Hybrid- submerged aerated filter (SRF) package treatment units along with primary lamella clarifier units, final settlement tanks, blowers and the air lines.

At present, effluent from the homes and commercial properties in the Castle Hill development is collected in a storage tank and transported away by tanker. However the town is set for rapid expansion.

In the March 2014 Budget, the then Chancellor promised 15,000 new homes in Ebbsfleet. New retail, business, leisure and commercial facilities along with schools and healthcare provision are expected to create up to 20,000 jobs.

WPL technical director Andrew Baird said: “This will be one of the largest installations WPL has built from start to finish and our biggest contract to date for the Hybrid-SAF.”

The first stage of the new treatment works which will serve 2,000 PE has been completed and comprises one primary lamella clarifier, eight Hybrid-SAF units connected in series and the final settlement tank. The second stage, on which work is expected to begin next year, will expand the plant to serve 4,000 PE.

The existing storage tank is adequate to serve the homes constructed during phase one of the Castle Hill development, but by late 2017 there are expected to be over 1,000 people living there.

At this point, WPL plan to move on to stage two, to be built alongside stage one, which will comprise a primary lamella clarifier, sludge storage tanks, eight additional WPL Hybrid-SAF units and an additional final settlement tank.

The area has protected groundwater so the Environment Agency stipulated that the new treatment plant had to be installed above ground. The plant will release wastewater treated to the high standard required by the Environment Agency into the Thames Estuary.

WPL installed the first stage of the plant in the spring of 2017 and it will become operational by late summer. Both phases of the plant are being manufactured offsite at WPL’s specialist facility in Waterlooville and delivered, installed and tested by WPL engineers. The project’s quick turnaround will keep costs down for the customer as minimal civil engineering is required for installation onsite.

In the future it may be decided to connect the Castle Hill development to mains sewerage, but at present none nearby have sufficient capacity. The modular configuration of WPL package plant has been designed to be highly flexible and will serve the town as it expands.

WPL managing director Gareth Jones said the company is already receiving enquiries from other housing developers considering the WPL Hybrid-SAF in their plans for wastewater treatment.

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