Revised Environmental Statement Vol 3
- Changes relating to aviation - Page 20
- Tranquility - Pages 52-53
- Assessment of impacts - Pages 56-59
- Noise - Pages 122-131
Revised Volume 4 , end of Section 5
Revised Environmental Statement Vol. 3
Changes relating to aviation – Page 20/Paragraph 1.10.3 – Points 5 & 6
5. The proposed use of Building 668 has been changed from ‘processing and storage of wood products’ to ‘Spitfire propeller workshop, parts and tool store associated with 669. The effect is anticipated to be neutral.
6. The proposed use of building 669 has been changed from ‘houses one spitfire’ to ‘aviation workshop and hangar for 8 heritage display aircraft in association with 668’. This change is considered to be significant enough that previous conclusions within the ES should be revisited. There is a reasonable opportunity for negative visual or noise impacts arising from this use that will be considered further in this ES. Background information has been provided by the tenants of these buildings and can be found in Volume 4.
Assessment of Impacts – Page 57
3.5.10 Reference to the CPRE tranquillity map (Figure LVIA Addendum 02) shows that the LCT in the immediate vicinity of the site experiences a range of tranquillity levels, with the least tranquil areas being those along the A1152 corridor, and extending to approximately the portion of the site north of the runway, save a more tranquil area in the north-eastern corner of the site. See Figure LVIA Addendum 02.
3.5.11 Following reference to the Sharps Acoustics LLP Noise impact Assessment, November 2012, Figure LVIA Addendum 01 illustrates the likely influence of noise levels arising from the eight heritage aircraft on the LCT. Within the site, and thus remote from public receptors, levels of ‘high annoyance’ would be experienced in close proximity to the north-eastern portion of the runway when it was in use for take off or landing, with the majority of the northern portion of the site being assessed as below the level of ‘low annoyance’, and the southern portion within the LCT ranging from less than ‘low annoyance’ to less than ‘moderate annoyance’. Beyond the site, all public receptors within the LCT would experience levels less than ‘low annoyance’, with the exception of the public footpath on the north-western perimeter of the site, which would correlate with the ‘low annoyance’ noise contour. The sense of tranquillity could also be affected by the presence of moving objects, and the flight paths from take off/landing would pass over a number of public footpaths within the LCT, e.g. to the south-west of the site in the vicinity of Eyke.
3.5.12 Such changes in noise levels and movement, and thus tranquillity, would not be continuous and would only be experienced when the runway was in use for take offs or landings, i.e. up to a maximum of 40 times per week, averaging six times a day.
3.5.13 As explained in Chapter 1 of this ES revision. Flight paths taken by airbourne aircraft are beyond the control of both the applicants and the local planning authority. In any event, aircraft stationed at the site are likely to move out, away from the immediate vicinity of the site, and the AONB; and are thus likely to have only nominal influence on the tranquillity of the area. Indeed it is aircraft flying to the area from airfields elsewhere and low flying military aircraft that are likely to affect tranquillity.
3.5.14 It is considered that the proposals would exert an influence of moderate magnitude (and thus medium-low adverse significance) on this portion of the Plateau Estates Farmlands LCT. Such an assessment is based on the effects of the views of vegetable boxes, wood storage, and soil product storage and the changes in tranquillity arising from noise/movement from the eight heritage aircraft using the runway (albeit experienced at a limited number of receptors , and on a limited number of occasions on any given day) Thus the no-action scenario (i.e a continuation of the baseline scenario with no mitigation measures implemented) would result in an impact of medium-low adverse significance.
Sharps Acoustic Report
Subject: Briefing note – Bentwaters 21st November 2012
Sharps Acoustics LLP (“SAL”) has been commissioned by Bentwaters Parks Ltd to undertake an assessment of the likely noise impact from aviation activity associated with a recent application at Bentwaters.
Details of the author of this Briefing Note are appended.
Mr Bainbridge of, Evolution Town Planning, has provided planning advice to SAL in this matter. We understand from Mr Bainbridge that a planning application has been made for a proposal that includes for one Spitfire aircraft based at Bentwaters. However, it is now envisaged that there would be eight aircraft based at Bentwaters in Buildings 668 and 669.
SAL has been asked to consider whether the noise impact that is likely to result from activity associated with this number of aircraft is likely to be “significant”, therefore, requiring assessment under the provisions of the “Town and Country Planning (Environmental Impact Assessment) Regulations, 2011”.
This information is intended to assist in the “general provisions relating to screening” – Part 2 of the regulations.
Assessment methodology and criteria
Conventional assessment methods
Since the Wilson Committee on the Problem of Noise released its “Final Report”, in 1963, aircraft noise has been assessed using three benchmark figures: LAeq16hr = 57 dB equating to “little annoyance”; LAeq16hr = 63 dB equating to “moderate annoyance” and LAeq16hr = 69 dB equating to “very much annoyance”. At that time the index used was the “noise and number index” but the LAeqT levels are equivalent values. These criteria relate to the impact from commercial aircraft.
These equivalent levels for “general aviation” noise are 7 dB more stringent and the impact descriptors have changed. These have been employed in this assessment of impact:
➢ LAeq16hr = 50 dB – low annoyance.
➢ LAeq16hr = 56 dB – moderate annoyance.
➢ LAeq16hr = 62 dB – high annoyance.
The contours of noise emission levels around Bentwaters have been based on these three levels.
The LAeq16hr index is, in effect, the average noise energy level over the 16 hr day period, 0700 to 2300 hours.
The National Planning Policy Framework
The National Planning Policy Framework (NPPF) was released on 27th March 2012. PPG 24 “Planning and Noise, was “replaced” by NPPF upon its release.
The NPPF states that planning decisions should: Aim to avoid noise from giving rise to significant adverse impacts on health and quality of life as a result of new development (Ref: NPPF paragraph 123).
** BCG notes that NPPF 123 also states that decisions should aim to "Identify and protect areas of tranquillity which have remained relatively undisturbed by noise and are prized for their recreational and amenity value for this reason."
The NPPF does not provide prescriptive advice in relation to noise. Therefore, it is necessary to consider advice, which may assist in the assessment of significant adverse impacts on health and quality of life, in other guidance documents. This available advice is discussed, below.
WHO Guidelines for Community Noise
The World Health Organisation, Guidelines for Community Noise, 1999, contain a matrix of guideline values showing “health” effects of noise in terms of “serious annoyance” and “moderate annoyance” during the day. It can be seen that in so far as the WHO Guidelines consider impacts in terms of “health” effects they are in accordance with the NPPF assessment criterion discussed above.
The WHO defines “health” as a state of complete physical, mental and social well-being and not just the absence of disease or infirmity. The WHO criteria for daytime (annoyance) may be considered to be “health” effects in this context.
The use of the word “critical” within the WHO Guidelines indicates that the guideline values are negative criteria, that is, they are values below which noise effects (such as annoyance) can be assumed to be negligible. They are not limits above which significant effects may necessarily occur; however, they are levels above which one should consider noise mitigation.
The WHO guideline values are LAeq16hr = 50 dB (moderate annoyance) and 55 dB (serious annoyance); and
NPL Interpretation of the WHO Guidelines
A report written by the National Physical Laboratory, commissioned by the Department for the Environment Transport and the Regions (1988), contains a section on the interpretation of a 1995 draft of the final 1999 Guidelines. There is not a material difference between the draft and the final document and, so the NPL advice is pertinent to the 1999 Guidelines.
The NPL report states:
“In essence, the WHO guidelines represent a consensus view of international expert opinion on the lowest threshold noise levels below which the occurrence rates of particular effects can be assumed to be negligible. Exceedances of the WHO guideline values do not necessarily imply significant noise impact and indeed, it may be that significant impacts do not occur until much higher degrees of noise exposure are reached.” (emphasis added).
It can be seen that the NPL report provides advice on likely noise levels that would result in “significant noise impact”. As such, the advice within the NPL report is in accordance with the criteria within NPPF and the EIA Regulations (see above).
“Much higher degrees of exposure” is not defined in noise level terms by NPL. However, a 3 dB change in ambient noise levels is not perceptible and a 10 dB change is roughly a doubling of loudness. On this basis, it is believed that a 10 dB change equates to the NPL criterion of “much higher degrees of exposure”.
Therefore, in SAL’s judgement, a “significant impact” would, therefore, result at a10 dB higher level than the WHO guideline values.
Although couched in different terms than the Wilson Committee derived assessment criteria, the NPPF assessment criteria are very similar.
Assessment of aircraft noise emission levels
The assessment of aircraft noise emission levels is conventionally undertaken by the use of a computer program. SAL uses the Integrated Noise Model (“INM”) which was designed by the Federal Aviation Authority.
INM allows a topographical ground model to be input to the program. Overlaid onto this ground model are the coordinates of runways and noise sensitive receivers. The operational variables, discussed above, which affect the noise emission levels from the site, are then input to the INM model.
The computer model then calculates the noise emission levels at ground level over what is termed a Cartesian grid. The grid size can be specified but was 1 metre by 1 metre in this case.
The INM model then joins noise emission levels at like values to form a set of contours – which are “smoothed” by the program. The values of the contours can be specified in the program.
The impact of aircraft noise is conventionally undertaken by assessing the noise emission level that would result on an average summer day (92 days from mid June to mid September).
Bentwaters has two operational runways orientated approximately east-west. These consist of the main runway and a reserve runway running parallel to the south. Aircraft prefer to depart into and arrive into the wind. This results in a modal split of 70% and 30% with the maximum departures and arrivals towards the west. This modal split has been assumed in this noise assessment.
At large, well-used airfields and airports it is necessary to consider the departure and arrival tracks – since there will be many of each. In the case of Bentwaters, the activity level is relatively low and, therefore only straight-out and straight-in flight tracks need to be considered (some “dispersion” around the departure track has been modelled).
It is understood from Bentwaters Parks Ltd that aerobatics will not be undertaken in the vicinity of the site but that aircraft will depart to, or arrive from, distant locations. This has been assumed in this assessment.
The significant separation distances and prevalence of structures and landscape features between aviation facilities on site and residential properties are such that the noise impact from ground operations would not be material or significant.
The types of aircraft that would use the facility are as follows:
• A Spitfire – (double cockpit) - already accounted for in the planning application
• A Spitfire – currently in pieces and not expected to be flying for another couple of years
• A YAK3
• Three Pitts Specials
• A Piper Super Cub
• A Piper L4 Cub
Therefore, the assessment has considered the impact of six aircraft (the YAK, three Pitts and two Pipers).
The computer modelling of noise emission levels and production of noise contours requires knowledge of the average number of flights (departures and arrivals) on an average summer day. This calculation should ignore one-off or very infrequent events such as an air-show. It is difficult to assess this likely level of usage, precisely. However, in discussions with the applicant, Mr Bainbridge has concluded that a maximum figure is 40 movements a week or 6 movements a day – a “movement” being an aircraft departure (take-off) or arrival (landing).
This assumes that, on average, half of the aircraft will depart and arrive back at the site every summer day. This is a conservative assumption and one which could be controlled by planning condition.
The assessment of aggregate noise emission levels is conventionally undertaken using generic aircraft types. There are two generic categories for “general aviation” aircraft:
• GASEFP – fixed pitch propeller aircraft;
• GASEVP – variable pitched propeller aircraft.
The latter of these aircraft tend to be those used for air-shows and displays; they are the noisier due to the higher power developed by the engine. Of the above aircraft, only the YAK has a variable pitched propeller. However, in order to introduce a safety margin into the assessment of noise emission levels, it is assumed in the modelling that all the aircraft at Bentwaters have variable pitched propellers.
Noise impact assessment
The attached appendix shows the contours that result from the above input assumptions. These contours have been drawn at the values discussed above.
It can be seen that the LAeq16hr = 50 dB contour does not extend to any residential or other noise sensitive premises. Therefore, the proposal would not result in even low annoyance. Accordingly, the proposal would not result in “significant adverse impacts on health or quality of life” – the test within NPPF.
The above assessment of noise impact is solely from the introduction of the six aircraft discussed above. However, it is appropriate to consider the cumulative impact for these aircraft with the Spitfire already operating at the site and the Spitfire that may operate in future. With eight aircraft operating rather than six, the noise emission levels would increase by 1.25 dB (10*log8/6). Such an increase in noise level is not material in impact terms.
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