Northumberland County Council Detailed Water Cycle Study October 2015 47070326 Prepared for: UNITED KINGDOM & IRELAND Northumberland County Council — Detailed Water Cycle Study REVISION SCHEDULE Rev Date Details Prepared by Reviewed by Approved by 1 November Draft for Comment Joanna Bolding Carl Pelling Jon Robinson 2014 Assistant Consultant Associate Director Operations Director Penny Pickerin Graduate Consultant Sarah Kelly Principal Consultant 2 July 2015 Revised Draft for Joanna Bolding Sarah Kelly Jon Robinson comment Hydrology Consultant Principal Consultant Operations Director Dr James Riley Associate Director 3 October Final Report Joanna Bolding Carl Pelling Jon Robinson 2015 Hydrology Consultant Associate Director Operations Director AECOM Infrastructure & Environment UK Limited Scott House Alencon Link Basingstoke Hants RG21 7PP Tel: +44 (0)1256 310200 Fax: +44 (0)1256 310201 www.ursglobal.com FINA L REPORT October 2015 2 Northumberland County Council — Detailed Water Cycle Study Limitations AECOM officially combined with URS Corporation on October 20, 2014 and all URS legacy companies including URS Infrastructure & Environment UK Limited became wholly owned subsidiaries of AECOM. 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Unless otherwise stated in this Report, the assessments made assume that the sites and facilities will continue to be used for their current purpose without significant changes. Copyright © This Report is the copyright of AECOM Infrastructure & Environment UK Limited. Any unauthorised reproduction or usage by any person other than the addressee is strictly prohibited. FINA L REPORT October 2015 3 Northumberland County Council — Detailed Water Cycle Study EXECUTIVE SUMMARY Northumberland County Council (NCC) has identified areas with potential for housing and employment development up until the year 2031 through the emerging Local Plan Core Strategy. The Full Draft Plan (December 2014) suggested that there is a requirement for 23,520 new dwellings over the plan period and there is the need to ensure that both the water environment and water services infrastructure has the capacity to sustain the level of development proposed. Following on from the Outline Water Cycle Study (WCS), produced in May 2012, the aim of the detailed WCS is to identify in detail the constraints on planned housing and employment growth imposed by the water cycle and define what infrastructure and mitigation is required to facilitate development. The detailed WCS will be used to inform the preparation of the Northumberland Infrastructure Delivery Plan (IDP). The purpose of the IDP is to help ensure that development and growth is enabled by the right infrastructure, delivered at the right time and in the most sustainable and effective way. Developed in partnership with stakeholders including Northumbrian Water (NW) and the Environment Agency, it serves to assist in coordinating and aligning the actions and investment plans of infrastructure providers and regulators to best effect, and in line with the Core Strategy. The detailed WCS has assessed each aspect of the water cycle at the strategic County level and at a detailed level for each potential development area option within a settlement area. Wastewater Treatment Assessment Wastewater Treatment Work (WwTW) Capacity The detailed WCS identified the following WwTW s across Northumberland that currently have limited or no capacity to accept or treat any further wastewater from the proposed development. These works may require an upgrade to accommodate the new development. If a new hydraulic consent is required at these works then it is likely the quality consents will be tightened to ensure no deterioration in the water environment. In the majority of cases this is likely to be achievable within current conventional treatment. • Hepscott WwTW, Humshaugh WwTW, Wark WwTW, Great Whittington WwTW and Newbiggin WwTW - No Headroom Available and no solution currently identified but a solution is likely to be possible within limits of conventional treatment • Tranwell WwTW - No Headroom Available and no solution available and WwTW cannot be upgraded • Lynemouth WwTW and Haydon Bridge WwTW - No Headroom Available until infiltration is removed • Rothbury WwTW, Cornhill on Tweed WwTW and Seahouses WwTW - No Headroom Available, NW Flow and Load investigations required • Pegswood WwTW - No Headroom available and likely WQ consent constraints • Allendale WwTW, Barrasford WwTW and Fourstones WwTW - Limited Headroom Available until surface water ingress is removed FINA L REPORT October 2015 4 Northumberland County Council — Detailed Water Cycle Study The Northumberland IDP (through annual updates) will be used to identify the WwTWs that require upgrades in liaison with NW. NW will commence investment procedures to provide capacity at the WwTWs once the potential development is certain. Sewer Network Capacity The detailed WCS identified several potential development area options where development is likely to exacerbate predicted performance issues with respect to sewer capacity. Possible infrastructure upgrades may be required in these areas before development can commence and include the areas of Prudhoe, Corbridge and Seaton Valley. NW have identified several potential development area options that they would object to due to the proximity of the new development to the WwTW. Therefore development should be located away from the WwTWs where possible or alternative potential development area options progressed. These areas include Wooler, Amble and Cornhill on Tweed. NW would also require a full odour assessment to support the planning application for some potential development area options. Therefore development should be steered away from the WwTWs or alternative potential development area options progressed for this settlement as a first choice option. Any new development must consider the impact of further urbanisation on the existing wastewater and surface water system, and discharge of surface water must be mitigated within the pumped limitations of the drained system. Wastewater Policy Recommendations The detailed assessment of wastewater capacity and infrastructure requirements within this WCS has identified several key recommendations, including the requirement for all planning applications in constrained areas to be subject to a pre-development enquiry with NW, and for detailed foul and surface water strategies to be built into masterplans for Morpeth, Ponteland, Prudhoe, Blyth and Scremerston. Ecology and Biodiversity Asse ssme nt The detailed WCS has assessed the impacts of increased discharges from WwTWs on designated water dependent ecological sites. An assessment of the level of risk was undertaken to determine where additional detailed analysis will need to be considered and agreed between NW and the Environment Agency as part of any future application to increase the permitted discharge volumes at key WwTWs. The risk assessment highlighted the following WwTWs as needing further detailed assessment as development comes forward: • Rothbury WwTW – discharges