Water quality

NE1: Water quality Effects of development 1. Development proposals will only be supported where they will not adversely affect the water quality of surface or underground water bodies (including rivers, canals, lakes, reservoirs, drinking water safeguard zones, source protection zones and groundwater aquifers). Development proposals should identify opportunities to improve water quality and groundwater quality where possible. 2. Development proposals affecting designated sites, priority habitats and species and their water catchment will need to demonstrate how water quality will be maintained, minimise surface water drainage and reduce pressure on the wastewater network. 3. Where there are potential adverse effects from windfall site development, developers must have full regard to the council’s latest Water Cycle Study. Development proposals must demonstrate how potential adverse impacts on water quality will be mitigated. In addition, the timing of development must consider the water infrastructure provider upgrades so a watercourse can treat wastewater to a higher standard. 4. A Water Framework Directive assessment is required when there are potential adverse impacts of development on a waterbody. This includes the potential of the development to prevent achievement of good ecological and chemical status of the waterbody in the future. Drinking Water Safeguard Zones and Source Protection Zones 5. In order to protect and improve water quality, potentially contaminating developments affecting principal aquifers, including the Chalk Aquifer, or within the county’s Drinking Water Safeguard Zones (surface water) or Source Protection Zones (groundwater) as defined by the Environment Agency and water companies, will need to demonstrate that surface water and groundwater are adequately protected to prevent a deterioration of water quality and pollution of the water source. 6. Sustainable Drainage Systems (SuDS) for developments located within Drinking Water safeguard zones and SPZ must carefully consider the risk of contamination to both surface and ground water sources and ensure appropriate mitigation measures are implemented to minimise impacts. 7. Developments which fall within a Groundwater Source Protection Zone will be required to be designed to allow for all the following: a) The potential to encounter shallow groundwater and the restriction on the use of soakaways. b) Avoiding direct discharge of hazardous substances to groundwater and prevent the input of pollutants and non-hazardous substances to groundwater. c) The potential for historic contamination to be encountered during development. d) Restrictions on deep penetrative foundation methods if contamination is encountered. 7.135 Development affecting waterbodies are expected to contribute to achieving the Water Framework Directive (WFD) objectives for these waterbodies. River Basin Management Plans are an Environment Agency tool used to deliver the WFD objectives and Buckinghamshire Council has an obligation to have regard for such plans. 7.136 It is important that water quality and quantity is maintained and enhanced by avoiding adverse effects of development on the water environment. Population growth and new housing are increasing pressure on waterbodies, including chalk streams, through changes in land use, demand for water, water quality and habitat loss. To reduce the impact of development, adequate infrastructure should be in place to ensure there is no increase in unsustainable abstraction or overloading of the sewer network or sewage treatment infrastructure. Mitigation responses include buffering development alongside chalk streams and implementing adequate management of runoffs (see also policies CC1 and CC2) including the use of infiltration and deep borehole SuDS to aid chalk aquifer recharge. 7.137 There are many opportunities for improving the ecological condition of waterways and the following examples will be particularly encouraged: a) locating open space next to rivers b) retaining river habitat as public space c) designing schemes that positively integrate with river corridor habitats. d) maximise health and wellbeing capacity of access to natural watercourses. e) integrating flood attenuation with landscape and biodiversity enhancements f) utilising bio-engineering solutions and avoiding hard bankside engineering. g) restoring natural river courses and corridors where these were previously modified, culverted or channelled (see policy NE2 Watercourses and associated corridors) h) incorporating features to support aquatic wildlife including fish and working with relevant river catchment partnerships to identify the most appropriate enhancements for watercourse habitats. 7.138 Many designated sites, priority habitats and species are dependent on good water quality particularly those that are water-dependent and hydrologically linked to groundwater and surface water bodies. These habitats will be sensitive or burdened from water quality pressures such as nutrient enrichment and increased pollutants. The policy requires stringent protection of the water quality in the catchment as this will help to prevent deterioration, maintain and/or restore the condition of water dependent designated sites (and wider) within the landscape. Information on the categories of designated or protected sites can be found here Protected sites and areas: how to review planning applications - GOV.UK. 7.139 Measures to minimise surface water drainage and reduce pressure on the wastewater network are identified in the latest Water Cycle Study. These should be used in the case of impacts on designated sites. The measures include greater use of Sustainable Drainage Systems, maximising surface water infiltration contributing to watercourse catchment-wide measures aimed to slow water flows. 7.140 Drinking water safeguard zones (surface water). Drinking Water Safeguarding Zones (WSZs) are the areas at risk of failing the drinking water protection objectives of the Water Environment (Water Framework Directive) (England & Wales) Regulations 2017. WSZs define areas where actions and measures will be targeted to address water contamination and avoid or minimise extra treatment needed by water companies. Actions proposed for each DWSZ are provided in Actions Plans produced by the Environment Agency with the water companies. 7.141 In Buckinghamshire’s DWSZs, the following general guidance applies to the use of SuDS: SuDS Type Guidance for Drinking Water Safeguard Zones in Buckinghamshire Infiltration SuDS (e.g., soakaways, infiltration basins) Not permitted in SPZ1 and avoided in SPZ2 unless proven safe. Lined or engineered alternatives preferred. Permeable paving Use only with impermeable liners in sensitive groundwater areas. Detention basins / wetlands Allowed with proper treatment. Avoid direct infiltration. Ensure sufficient retention time. Swales, filter strips Acceptable for surface water pre-treatment. Green roofs Low risk; acceptable in all locations. 7.142 The Environment Agency has designated in certain areas of Buckinghamshire Source Protection Zones (groundwater) for clean water supply, and principal aquifers, (including the chalk aquifer) which are sensitive receptors. Potential risks to these receptors come from contaminated land with past historic uses of some sites. In other cases, it can be linked to pollutants in surface water which infiltrate to the groundwater table. 7.143 Source Protection Zones (SPZs) are categorised into three zones, 1-3, with one being most sensitive to pollution, and three representing the lowest risk but still within the groundwater catchment of the abstraction. The Environment Agency’s Manual to Produce Groundwater Source Protection Zones 8, details position statements which provide information about the Environment Agency's approach to managing and protecting groundwater. Proposed development locations within or close to Source Protection Zones, should be assessed in relation to the relevant Environment Agency position statements. 8 Manual to produce Groundwater Source Protection Zones, Environment Agency (2019). Accessed online at: https://www.gov.uk/government/publications/groundwater-source-protection-zones-spzproduction-manual on: 10/02/2023. 7.144 All developments should consider the sensitivity of the underlying Chalk Aquifer and the large number of public water abstractions in the areas protected by Source Protection Zones. 7.145 In considering SuDS solutions, development proposals must consider the need to protect surface water and groundwater quality, especially where infiltration techniques are proposed. SuDS which contribute to removing pollutants, and to managing flows, will be strongly preferred. See SuDS in Source Protection Zones guidance: suds-in-spz-guidance.pdf