Water Cycle Study - East Devon District Council

Ref EWCS April 2010
Exeter and East Devon Water Cycle Study
Exeter Countess Wear
6.4.5 Exeter Countess Wear WwTW has the consented capacity for the total development
scenario of 21,500 new homes up to 2026. This scenario does not breach the current
flow consent. The Environment Agency have stated that they have concerns regarding the
discharges from Countess Wear as the WwTW discharges to the Exe Estuary which
contains a SPA and Ramsar site. The Exe estuary is considered to have elevated nutrient
levels due to the inputs from WwTWs and diffuse agricultural sources within the
catchment. Due to these elevated nutrient levels, the estuary may be vulnerable to
biological instabilities in the future if a nutrient concentration ‘tipping-point’ is reached.
6.4.6 The EA state in their response to the Draft RSS Panel Report that; “with monitoring in
place to detect early signs of stress in the estuary ecosystem, and scope for action on nutrient
loads in the Exe into the future from both point and diffuse sources across the catchment, we
consider that this provides sufficient safeguards for development to move forward at Exeter.” [EA
2006]
6.4.7 We therefore do not consider water environmental capacity to be a constraint to growth
in Exeter. However, we recommend that Exeter City, the Environment Agency and
South West Water work in partnership to develop a monitoring and development
intervention programme to manage the risk of deterioration in the Exe.
Cranbrook
6.4.8 Once operational, the proposed Cranbrook WwTW will discharge to the River Clyst.
Cranbrook WwTW has planned consented capacity for growth up to 2021 (7500
dwellings) but for growth beyond this level the flow consent will be breached. The River
Clyst is currently at moderate physiochemical status and poor biological and ecological
status. The consent for the new works will have taken the Water Framework Directive
standards into account, therefore the poor status should not be considered as a
constraint to growth.
6.4.9 In order to meet WFD good status the BOD and ammonia consents may require
tightening as part of the River Basin Management Plan activities. As the ammonia consent
is currently at 2, this may require a tightening which is beyond best available technology
(currently considered to be at 1mg/l), although this is not considered likely.
Axminster (Kilmington)
6.4.10 Axminster (Kilmington) WwTW discharges to the River Axe. There is consented capacity
at the WwTW for the 1000 additional dwellings up to 2026. However, the River Axe is
currently at moderate physiochemical status and is at poor biological and ecological
status. Therefore the BOD and ammonia consents may require tightening to meet WFD
good status.
6.4.11 The EA state in their response to the Draft RSS Panel Report [EA 2006] that although
they have concerns regarding the River Axe already failing its phosphate standard, due to
recent nutrient stripping initiatives, they consider that there is capacity for the levels of
development proposed in this catchment.
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