Warblington Farm Study
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Havant Borough Council Review of the Warblington Farm Mitigation Option for Nutrient Neutral Development in the Havant Borough ___________________________________________________ Report for Havant Borough Council ED 13715100 | Issue Number 3 | Date 15/06/2020 Ricardo Energy & Environment Havant Borough Council | i Customer: Contact: Havant Borough Council Claire Pitcher Ricardo Energy & Environment Customer reference: 30 Eastbourne Terrace, Paddington, London, W2 6LA, United Kingdom N/A Confidentiality, copyright & reproduction: t: +44 (0) 1235 75 3458 e: [email protected] This report is the Copyright of Havant Borough Council. It has been prepared by Ricardo Energy & Environment, a trading name of Ricardo-AEA Ricardo is certificated to ISO9001, ISO14001 Ltd, under contract to Havant Borough Council. and OHSAS18001 The contents of this report may not be reproduced in whole or in part, nor passed to any Authors: organisation or person without the specific prior Gabriel Streich-Connor, Matthew Edwards, written permission of Havant Borough Council. Claire Pitcher Ricardo Energy & Environment accepts no liability whatsoever to any third party for any loss Approved By: or damage arising from any interpretation or use of the information contained in this report, or Jenny Mant reliance on any views expressed therein. Date: 15 June 2020 Ricardo Energy & Environment reference: Ref: ED13715100- Issue Number 3 Ricardo Confidential Ref: Ricardo/ED13715100/Issue Number 3 Ricardo Energy & Environment Havant Borough Council | ii Table of contents 1 Introduction ................................................................................................................ 1 1.1 Background and Purpose of the Report ............................................................................ 1 1.2 The Study Area.................................................................................................................. 1 1.3 Report Structure ................................................................................................................ 1 2 The Habitats Regulations Assessment Process ...................................................... 3 3 The Water Environment in Chichester Harbour ....................................................... 4 3.1 Baseline Water Quality ...................................................................................................... 4 3.1.1 Nitrogen Loading ...................................................................................................... 4 3.1.2 Spatial and Temporal Patterns in Nitrogen Concentrations in Chichester Harbour. 5 3.2 How Thornham Wastewater Treatment Works (WwTW) Operates .................................. 7 4 The Water Environment in Langstone Harbour ....................................................... 8 4.1 Baseline Water Quality ...................................................................................................... 8 4.1.1 Nitrogen Loading ...................................................................................................... 8 4.1.2 Spatial and Temporal Patterns in Nitrogen Concentrations in Langstone Harbour . 9 4.2 How Budds Farm Wastewater Treatment Works (WwTW) Operates ............................. 11 5 Potential Effects to be Mitigated ............................................................................. 14 5.3.1 Thornham WwTW .................................................................................................. 19 5.3.1.1 Source and Pathway for Impacts ................................................................. 19 5.3.1.2 Receptors ..................................................................................................... 19 5.3.2 Budds Farm WwTW ............................................................................................... 20 5.3.2.1 Source and Pathways for Impacts ............................................................... 20 5.3.2.2 Receptors ..................................................................................................... 21 6 Review of the Warblington Farm Mitigation Proposal ........................................... 23 6.1 Overview of Mitigation Requirements in HRA Process ................................................... 23 6.2 Existing Land Use ........................................................................................................... 24 6.3 Application of the Nutrient Budget Calculator ................................................................. 26 6.4 Suitability of Mitigation to Conclude No Adverse Effect .................................................. 26 7 Conclusions and Next Steps ................................................................................... 29 Appendices Appendix A Designated Sites Tables Ricardo Confidential Ref: Ricardo/ED13715100/Issue Number 3 Ricardo Energy & Environment Havant Borough Council | 1 1 Introduction 1.1 Background and Purpose of the Report New housing growth in the Solent area is affected by the change in case law as a result in the Dutch Case1. This is due to concerns that likely significant effects (through the Habitats Regulations Assessment (HRA) process) will occur to the internationally designated sites2 from increased or continued nutrient loading, arising from the additional wastewater generated by the new development. Work is ongoing to establish the source-pathway-receptors, and likelihood of an adverse effect, due to housing development within the jurisdiction of Havant Borough Council (HBC) and the southern parishes of East Hampshire District Council (EHDC) which either drain to Budds Farm Wastewater Treatment Works (WwTW) in Langstone Harbour or to Thornham WwTW in Chichester Harbour. Both harbours are part of the Solent Maritime Special Area of Conservation (SAC), and the Chichester and Langstone Harbours Special Protection Area (SPA) and Ramsar site. The harbours also connect to the wider Solent coastal system with connectivity to Portsmouth Harbour SPA and Ramsar, and which is designated as part of the Solent and Dorset Coast SPA, and areas are part of the Solent and Southampton Water SPA and Ramsar. Should adverse effects from new housing development projects be identified through the Appropriate Assessment stage of the HRA process (i.e. Stage 2), then mitigation to ensure no adverse effect on the integrity of the European site(s) in question will be required before planning permission can be granted. Havant BC has identified Warblington Farm as a potentially suitable mitigation option to be used by developers for offsetting increases in nitrogen loading from new housing development, by taking this area of land out of intensive agricultural use; an existing source of nitrogen to the system. Consideration is being given as to whether sufficient ‘credits’ are available to mitigate for new housing in the Havant Borough and southern parishes of East Hampshire. This report therefore aims to summarise the pathways for impact from the new housing development and establish using information provided by Havant BC, whether Warblington Farm would provide effective and reliable mitigation for new development in Emsworth, and the wider Havant Borough and southern parishes of East Hampshire. 1.2 The Study Area The study area comprises Chichester Harbour where Thornham WwTW discharges, which serves the area of Emsworth and Langstone Harbour which serves the remainder of Havant Borough and the southern parishes of East Hampshire which discharge to Budds Farm WwTW. Offshore areas within the Solent are considered due to offsite functional habitat usage, the long-sea outfall from Budds Farm WwTW and the cumulative impact of nutrient loading in the wider coastal system. 1.3 Report Structure This report is divided into the following sections: • Section 2: The HRA Process • Section 3: The Water Environment in Chichester Harbour • Section 4: The Water Environment in Langstone Harbour • Section 5: Potential Effects to be Mitigated • Section 6: Review of the Warblington Farm Mitigation Proposal 1 Full reference is Cooperatie Mobilisation for the Environment UA and College van gedeputeerde staten van Noord-Brabant (Case C-293/17 and C294/17) available at https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:62017CA0293 2 Special Areas of Conservation, Special Protection Areas and Ramsar sites, collectively referred to as European sites. Ricardo Confidential Ref: Ricardo/ED13715100/Issue Number 3 Ricardo Energy & Environment Havant Borough Council | 2 • Section 7: Conclusions and next steps. Information on Budds Farm WwTW and Langstone Harbour is provided from the Review of the Need for Nutrient Neutral Development in the Budds Farm Wastewater Treatment Works catchment June 2020, as necessary (see report for full details and background). Ricardo Confidential Ref: Ricardo/ED13715100/Issue Number 3 Ricardo Energy & Environment Havant Borough Council | 3 2 The Habitats Regulations Assessment Process All new developments within Havant BC and the southern parishes of East Hampshire will be required to complete a HRA Stage 1 Screening and Stage 2 Appropriate Assessment under the Conservation of Habitats and Species Regulations 2017 (amended) given the risk of increases in nutrient loading affecting the European designated sites of the Solent. The Stage 1 Screening assessment is a relatively short exercise used to determine whether there is a ‘possibility’ or ‘risk’ of a significant effect, in the absence of any mitigation, that requires further