Tom Lloyd, Entec
(free)Northumbrian Water Limited (NWL) currently discharge fully treated and disinfected effluent to
Cowbridge Beck from their 60,000 population equivalent (pe) Billingham Sewage Treatment
Works (STW) on Teesside. The beck flows into Greatham Creek and Seal Sands, an
internationally important bird reserve and SSSI, which the Environment Agency (EA) wish to
protect by tightening nutrient discharge consents by December 2008. This paper describes
the development of the consequent treatment options by NWL, notably extended aeration and
tertiary sand filters, with associated chemical dosing. However, whole life costing identified a
cost effective alternative to transfer flows without further treatment direct to the North Sea via
existing NWL coastal infrastructure at Seaton Carew, some 7km away.
Habitat surveys revealed the presence of great crested newts (GCNs), triggering the need for
a GCN licence from DEFRA and installation, under NWL’s first specialist GCN contract, of
nearly 6km of newt barriers and traps before the main construction starts in September 2007.
The main construction contract includes a tunnelled rail crossing, two pipebridge watercourse
crossings, and significant access and programming constraints, developed to minimise both
the environmental impact and construction effort.
KEY WORDS
Ammonia; great crested newts; outfall; phosphorus removal; tertiary treatment; transfer
pipeline;
Aqua Enviro Ltd
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