Chard treatment works cleared for take-off
Chard in Somerset home of the first powered flight is the location for Wessex Water's most recent wastewater treatment works. Built to cope with the town's population growth until the year 2013, the £8 million treatment works has also been designed to blend in with the environment, resulting in the creation of several new wildlife habitats.
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.