Policy DM11 Environmental hazards
Health and Safety Executive areas
Development within the specified distances from the sites identified as notifiable installations or the development of new notifiable installations must take account of any risks involved and the need for appropriate separation between hazardous installations and incompatible uses.
Subsidence
In locations where the best available evidence shows that the viability of development could be affected by:
a) serious and exceptional risk of subsidence, and/or
b) serious and exceptional risk of ground instability or potentially unstable land on or adjoining the site
developers will be required, as part of any viability assessment necessary under policy DM33, to show that they have investigated and taken account of such risk by identifying appropriate design elements, exceptional engineering works or other mitigation measures which are necessary to satisfactorily address that risk and enable a viable development to proceed.
Contamination
Permission for development or change of use within locations where it is known or suspected that land is contaminated or within 250m of a former landfill site (as shown on the Policies map) will only be granted where:
a) it can be demonstrated by site investigations that there is no evidence of contamination which is likely to prevent the grant of planning permission; or
b) where evidence of contamination exists, provision is made for any site remediation measures necessary to deal appropriately with that contamination before commencement.
Air and Water Quality
In areas where an Air Quality Management Area (AQMA) has been declared (under the Environment Act, 1995), development which is likely to have an impact on air quality will be required to take particular account of the air quality action plan for that area. Where the action plan identifies poor or deteriorating air quality as an issue in localised areas within the AQMA, development will be required to incorporate measures which will mitigate against the effects of existing or potential further deterioration in local air quality through design, density, disposition of uses or travel demand management as appropriate, on a case-by-case basis.
Development proposals falling within designated groundwater source protection zones or affecting a principal aquifer (as defined by the Environment Agency) are required to demonstrate that appropriate measures have been incorporated to minimise any risk of pollution to the water source. Any development which has the potential to pollute should demonstrate that pollution mitigation measures, protective of the water environment, have been incorporated into the development. Additional regard should be had where a site falls within a Source Protection Zone (in particular zone 1), on a Principal Aquifer or adjacent to a watercourse.
Noise
To help reduce the impact of noise, appropriate and proportionate mitigating measures will be required and appropriate limiting conditions will be attached to permissions for development which, on the best available evidence, is likely to:
a) give rise to sources of environmental noise, neighbour noise, or neighbourhood noise which will have some adverse impact on the health, well-being and quality of life of existing adjoining and nearby occupiers; or
b) result in some adverse impact on the health, well-being and quality of life of future occupiers of the proposed development by increasing their potential exposure to existing sources of noise in the vicinity.
In determining individual proposals for noise generating uses or uses which may increase noise exposure, account will be taken of the operational needs of business, the character and function of the area, the levels of neighbourhood noise which might be reasonably expected in the daytime, evening and late at night, the disposition of uses and activities in the vicinity in relation to residential occupation, and the reasonable expectation of residents for a high standard of amenity and outlook and a period of quiet enjoyment for at least part of the day.
Permission may be refused exceptionally in cases where the exposure of adjoining occupiers to noise from the proposed development could not be reduced through planning conditions or other mitigating measures below the significant observed adverse effect level (SOAEL) which is assessed as appropriate for that location.
Supplementary text
11.1 In accordance with the provisions of the NPPF, local authorities must ensure that sites are suitable for development taking account of ground conditions, pollution arising from previous uses and any proposals for land remediation.
Health and Safety Executive areas
11.2 Sites and installations which have quantities of hazardous substances present on-site are designated as notifiable installations by the Health and Safety Executive.
11.3 The following sites are currently identified as notifiable installations as they pose specific issues of safety and possible harm to human health in adjoining areas:
- Calor Gas, Livestock Market site
- Briar Chemicals Ltd, Sweet Briar Road
- Heigham Waterworks, Waterworks Road
- Gas Holders – Bishop Bridge Road and Cremorne Lane
11.4 The specified distances are identified on the map in appendix 2. The distances and notifiable installations are subject to change over time.
11.5 It is considered prudent to control the kinds of development which are permitted in the vicinity of such installations and the council will consult the Health and Safety Executive on planning applications within the specified distances of these installations. In determining whether or not to grant permission for a development within the consultation distances, the risks to the proposed development and the nature of that development will be taken into account.
11.6 The siting of new notifiable installations will be managed with the aim of keeping the installations separate from housing and other sensitive land uses with which the installations would be incompatible. The council will consult the Health and Safety Executive and the Environment Agency about the siting of proposals for new notifiable installations.
Subsidence
11.7 In Norwich numerous examples of subsidence have been recorded historically due to ground instability. These conditions affect particular parts of the city, due both to the vulnerability of the underlying chalk geology to solution cavities and to historic shallow chalk and flint workings within it. Former landfill sites are also of concern and are an indirect hazard associated with ground movement.
11.8 Proposals for development in affected areas will generally need to take relevant technical advice on the most effective means of overcoming any potential problems. Advances in building construction techniques mean that site constraints which previously prevented development on unstable ground may be capable of being addressed satisfactorily by suitable foundation technologies. These measures can be required in the great majority of cases through the building control process. Only where there are exceptionally high risks of subsidence which objective technical evidence shows cannot be resolved by suitable mitigation measures should development not go ahead. The aim should not be to prevent the development of such land altogether, though in some extreme cases that may be the appropriate response. Rather it is to ensure that development is suitable and that the physical constraints on the land are taken into account at all stages of the planning process.
11.9 It is the responsibility of the developer to determine whether land is suitable for a particular purpose, and to factor in costs associated with subsidence or land instability as part of the overall assessment of scheme viability. Developers will not normally need to submit detailed technical information with a planning application on the degree of subsidence risk or land instability associated with a site or the engineering works necessary to address it to enable an informed assessment to be made on the planning merits of the scheme. However, in cases where instability is known or suspected to pose serious risks, there may be particular cost implications for the viability of development which need to be taken account of in negotiations relating to planning obligations under policy DM33.
11.10 Should an independent viability assessment be necessary to resolve this issue, sufficient information should then be submitted to enable an informed judgement to be made on the construction cost implications of any measures to address subsidence risk and/or ground instability and their impact on overall development viability.
11.11 Partial mapped information on the incidence of chalk workings which are likely to impact on ground conditions is held by the city council’s retained property advisors and areas of known risk can thus be identified during the application validation process. However, the lack of comprehensive information on the extent of these workings makes it impractical to indicate precise areas of elevated risk on a map or to identify them by other means within the plan. Where such areas of risk are known to exist which may have a significant potential impact on development costs, case officers will discuss the issue at an early stage with applicants and will attach an informative to decisions on relevant planning applications advising of the risk.
11.12 Additional to the specific risk from chalk workings, it is known that the underlying geology of Norwich can cause a small degree of risk to foundations throughout the city, mainly resulting from undermining from water leakage. The existence of such workings does not imply that development is inappropriate or undesirable. Rather, the highlighting of this issue within the policy is intended to indicate to prospective developers that there may be some degree of risk, and that appropriate design elements, engineering works or other mitigation measures may be necessary to enable viable development to proceed.
Contamination
11.13 The council supports the use of the planning system to bring areas of contaminated land back into use; however the authority must satisfy itself that the potential for contamination and any risks arising are properly assessed. Affected development must incorporate remediation and management measures. These must deal with risks of water pollution, contamination from site works and with health risks for end users.
11.14 Where a site is affected by contamination or land stability issues, the responsibility for securing a safe development rests with the developer and/or landowner (NPPF, paragraph 120). Accordingly, the developer should be able to demonstrate that an appropriate site investigation has been undertaken which shows no evidence of contamination on the site likely to affect the grant of a planning permission. The report should be submitted with a planning application and the council will consult the Environment Agency and take account of environmental health officer advice in assessing such reports. Local technical guidance is available (prepared by the Norfolk Environmental Protection Group for adoption by individual districts) setting out the requirements for the content and scope of such reports.
11.15 If contamination is shown the developer must also demonstrate that a method of treatment necessary to deal with any hazards found has been agreed or conditions requiring such measures to be implemented can be attached. Such measures must ensure that water resources and other environmental resources are not adversely affected, further migration of gases and substances is prevented, and that appropriate remediation takes place on-site to secure a safe development that is suitable for its proposed use.
Air and water quality
11.16 Any consideration of the quality of air and potential impacts arising from development is capable of being a material planning consideration. In considering proposals the council must take appropriate account of the risks from pollution, and how these can be managed or reduced. Planning and pollution controls are separate but complementary. The planning system plays an important role in determining the location of development which may either give rise to, or be exposed to potential risks from, pollution. Development which may give rise to airborne emissions of harmful substances will be required to assess their possible direct and indirect impacts on health, the natural environment and general amenity. Appropriate mitigation measures should be identified. Particular consideration should be given to pollution issues for development proposals in and around Air Quality Management Areas (AQMAs).
11.17 Particular areas of central Norwich: the castle area, Grapes Hill, St Augustines Street and Riverside Road have experienced levels of nitrogen dioxide higher than the annual air quality objective, as a result of vehicle congestion on these heavily trafficked sections of the road network. These were formerly designated as individual Air Quality Management Areas (AQMAs). More recent monitoring of air quality has shown levels of nitrogen dioxide higher than the annual objective at additional “hot spots” – part of King Street around its junction with Carrow Road and at Bull Close Road. At Grapes Hill traffic management measures appear to have led to an improvement in air quality on a sustained basis, whilst the introduction of a low emission zone in Castle Meadow has produced encouraging results albeit that limit values are yet to be met on a sustained basis. The recent implementation of a gyratory system in the north of the city centre which diverts inbound traffic away from St. Augustines Street appears to be delivering results in terms of reduced pollution levels in this area.
11.18 The air quality issues identified at Bull Close Road and King Street would justify the formal declaration of additional AQMAs for these areas. However in view of the costs and the procedural and legal complexity of declaring multiple smaller AQMAs, the council has now declared a single AQMA for a larger area of the city centre, in which localised air quality “hot spots” can be identified and addressed. This approach enables a greater range of transport interventions to be used in tackling air quality, such as those which are not geographically specific (for example parking controls). Ongoing monitoring following the adoption of the new AQMA has indicated a number of locations in the city centre where nitrogen dioxide levels remain elevated, however the declaration of a wider AQMA does not imply that air quality issues are of equal severity across the entire area, merely that developers should take account of these issues where the air quality action plan identifies them.
11.19 In considering development proposals likely to have implications for air quality, development management officers will take account of any site specific advice from the council’s environmental protection officers on appropriate mitigation measures. Technical guidance for developers on the available means to address air quality issues is available on a county wide basis in support of this policy.
11.20 It is important that new development which may give rise to a potential adverse impact on either air or water quality is responsibly managed to reduce and mitigate that risk. Since the impacts of environmental pollution are addressed mainly through other legislation and pollution control permitting regimes, the planning decision-making process informed by this plan must focus on the suitability and the impact of the development or use itself (NPPF, paragraph 122) and not seek to revisit issues already satisfactorily dealt with through other pollution control mechanisms.
11.21 Developers must be mindful that the pollution of ground water and/or surface water is an offence under the Water Resources Act 1991. Also, the Water Framework Directive requires there to be no deterioration in water status and for good status to be achieved in the long-term. The proximity of the Norfolk and Suffolk Broads and other valued habitats within and in close proximity to the city makes it particularly important that developers give consideration to both these issues in formulating development proposals.
11.22 The whole of Norwich (with the exception of a sector between the Newmarket and Ipswich Roads south of the outer ring road) falls within one of the designated Ground Water Source Protection Zones SPZ1, 2 and 3 and the majority of the city overlies principal or secondary aquifers defined by the Environment Agency. As these zones are likely to be redefined from time to time on the basis of up-to-date technical modelling, they are not shown in this plan or on the Policies map, but can be consulted on the Environment Agency website. The council will take into account any relevant advice from the council’s environmental health officers and the Environment Agency in assessing proposals likely to have a significant impact on air or water quality. Source Protection Zone 1 is particularly vulnerable to contamination, therefore a risk assessment will normally be required before anything other than clean roof water is discharged to ground in those areas.
Noise
11.23 The NPPF in Section 11: Conserving and enhancing the natural environment requires planning policies and decisions to avoid noise from giving rise to significant adverse impacts on health and the quality of life as the result of new development, and to mitigate and reduce to a minimum other adverse impacts on health and quality of life. This means both that development likely to give rise to noise should not itself give rise to unacceptable levels of noise pollution, and that other development, particularly residential development, should be planned and located so as not to expose residents or occupiers to excessive noise levels from existing uses and activities.
11.24 This part of the policy should be read alongside other relevant policies of the plan seeking to manage particular forms of development (in particular late night activities subject to policy DM23 and hot food takeaways subject to policy DM24). It seeks to apply a precautionary principle, recognising that it will be necessary in certain circumstances to limit the impacts of noise generating uses in the interests of amenity, albeit not to the extent where it would impact unreasonably on the operating conditions of business (see policy DM2). The acceptability and the precise impact of noise will vary according to where the proposed development is located, but the expectation is that in the city centre the intensity of commercial uses and activities, particularly those relating to the evening and late night economy, will typically generate higher levels of neighbourhood noise than would characterise a quiet suburban area, and that some noise in these areas is inevitable. Accordingly, relative noise sensitivity and the level at which noise becomes significantly harmful to health and quality of life (the “significant observed adverse effect level” or SOAEL) will vary from place to place, and this will have a bearing on the scope and nature of any conditions or mitigating measures required.
11.25 In framing conditions necessary to manage and mitigate the impact of noise either by means of insulation, limits on amplified sound or mechanical noise or the restriction of hours of operation, account will be taken of the relevant technical advice from environmental health officers on what is appropriate in individual cases. Such conditions will be proportionate and reasonable to the circumstances of the case.
References
- NPPF: CLG, 2012: Section 11: Conserving and enhancing the natural environment: Preventing unacceptable risks from pollution and land instability, considerations for planning policies and decisions relating to the impact of noise on and from existing and proposed development.
- National Planning Practice Guidance, CLG 2014: Air quality; Hazardous substances; Health and well-being; Land affected by contamination; Land stability; Light pollution; Noise; Water supply, wastewater and water quality.
- Land contamination reports – advice for consultants and developers; Norfolk Environmental Protection Group - Contaminated Land Officers Group, May 2009.
- Planning and pollution in Norfolk, March 2012.
- Technical guidance: Development on land affected by contamination, Norfolk Environmental Protection Group.
- Technical guidance: Air quality and land use planning, Norfolk Environmental Protection Group
- Air quality review and assessment annual progress reports: Norwich City Council, various dates.
- Noise Policy Statement for England (NPSE): DEFRA, March 2010.
