Chard treatment works cleared for take-off

The new £8 million wastewater treatment works will help Chard in Somerset to

cope with popultion grwoth, said local MP Paddy Ashdown at its opening. The

works has been designed to cope with the anticipated rise in population

between now and the year 2013.

The works, situated on a greenfield site, can treat the wastewater from a

population of up to 14,200 as well as waste from local industry. One of the

town¹s local industries resulted in an extra stage being incorporated into

the treatment cycle. Fat deposits produced by the town¹s meat factories

prompted a special fat removal system.

Small bubbles are introduced into the bottom of a fat removal tank which

helps the fat float to the surface where it is then scraped off. Until the

new works came on line, a worker had to be on-site virtually all the time to

clear out the system whenever it got clogged with fat. Now, the site will

only be visited once week by Wessex Water as a telemetry system links the

works to Wessex¹s control centre at Bath.

After screening and grit and fat removal, the wastewater is distributed

between two primary settlement tanks before progressing to the biological

treatment stage.

Currently there are four operational biological filters but there is room on

site for a fifth to be constructed if required. Each of the four trickling

filter tanks are 2.5m deep and are filled with recycled plastic media which

houses the bacteria responsible for treating the effluent.

Two final settlement tanks complete the last stage of treatment and allow

fine particles to settle out further before the water is discharged into the

neighbouring River Isle.

As part of the development of the new works, two areas of wet meadow and

woodland habitat were created. These will flood in the winter months,

increasing habitat diversity and providing suitable conditions for various

wildlife including butterflies, birds and the water vole.

A flood berm, or storage area, has also been created adjacent to the River

Isle that will compensate for the reduction of flood plain resulting from

the construction of the works, creating a marshy wetland habitat.

Clumps of alder, willow trees and shrubs have been planted along the river’s

edge to provide some shade to the river and create a suitable habitat for

birds such as kingfishers, dippers and wagtails.

The second wetland area has been created to the east of the treatment works

bordering the outflow ditch carrying the discharge to the River Isle. In

the long term, these two areas will be managed for conservation.

Hedgerows of native species have been planted along the boundary of the

treatment works, while ash and oak trees have been planted alongside the

access track to increase the habitat diversity and screen the works,

enhancing the landscape surrounding the plant.

All biosolids produced as a result of the treatment processes are pumped to

a storage tank where any liquid is removed. this liquid is pumped to the

beginning of the works to receive full treatment.The remaining solids are

taken off-site to Wessex Water’s treatment centres at Yeovil or Taunton.

After a successful take off, the treatment works is set to be cruising

without any problems well into the next millennium, improving not only

sewage treatment for the residents of Chard but also the local environment.