We attach a Note together with tables and figures which respond to your letter of 18 March and the letter from SSE of 25 February.

Transcription

1 I CMS Cameron McKenna LLP Planning Central Casework Division Communities and Local Government 1/JI Eland Hous e Bressenden Place London SW1E 5DU FAO: Mr Richard Watson Department for Transport 1/18 Great Minster House 76 Marsham Street London SW1P 3DR Mitre House 160 Aldersgate Street London EC1A 4D D Tel +44(0) Fax+44(0) DX BARBICAN 2 Tel +44(0) alistair.watson@cms-cmck.com FAO: Mr John Faulkner Your Ref: APP/C 1570/A/06/ Our Ref: ASW/ April By Post and Dear Sirs Our Clients: BAA Ltd and Stansted Airport Ltd Town and Country Planning Act Section 7 8 Appeal made by BAA Ltd and Stansted Airport Ltd against the decision of Uttlesford District Council Land at Stansted Airport, Stansted, Essex CM241Q W We attach a Note together with tables and figures which respond to your letter of 18 March and the letter from SSE of 25 February. Yours faithfully CWI..,4 a~vv~~ "Wv~~ kt"~f CMS Cameron McKenna LL P cc All Rule 6 Parties to the G1 Inquiry ( ) CMS Cameron McKenna LLP is a limited liability partnership registered in England and Wales with registration number OC It is a body corporate which has members whom we refer to as "partners". A list of members and their professional qualifications is open to inspection at the registered office, Mitre House, 160 Aldersgate Street, London EC1A 4DD. Members are either solicitors or registered foreign lawyers. Regulated by the Solicitors Regulation Authority. CMS Cameron McKenna LLP is a member of the CMS alliance of independent European law firms. CMS offices and associated offices : Amsterdam, Berlin, Brussels, London, Madrid, Paris, Rome, Vienna, Zurich, Aberdeen, Algiers, Antwerp, Arnhem, Beijing, Belgrade, Bratislava, Bristol, Bucharest, Budapest, Buenos Aires, Casablanca, Cologne, Dresden, Dusseldorf, Edinburgh, Frankfurt, Hamburg, Kyiv, Leipzig, Ljubljana, Lyon, Marbella, Milan, Montevideo, Moscow, Munich, New York, Prague, Sao Paulo, Sarajevo, Seville, Shanghai, Sofia, Strasbourg, Stuttgart, Utrecht Warsaw and Zagreb. The members of CMS are in association with The Levant Lawyers with offices in Beirut, Abu Dhabi, Dubai and Kuwait. Notice : the firm does not accept service by of court proceedings, other processes or formal notices of any kind without specific prior written agreement.

2 13244/msp 3rd April 2008 Replies to the Questions Raised by SSE 25th February For ease of reference the questions from the SSE letter are reproduced in italics below followed by the corresponding answers in normal font. Numbering of tables and figures generally corresponds to that given in the original documents. The revised concentrations i n these tables are shown in italics. Where new tables have been prepared specifically to reply to these questions they are assigned the question number to which they refer. All tables and figures are grouped together at the end of the text and follow the order of the questions. At how many real time monitoring sites was NOx measured during 2006/07, where were they sited and over what periods was monitoring carried out? There were six monitoring sites used over a 12 month period (April 2006 to March 2007). The details of the sites and their locations are set out in new Table 1 2. What were the actual results and what were the predicted values? The annual mean NOx, and NO2 concentrations and the ratification status of these data are given in new Table 2a. New Tables 2b and 2c show a comparison of the total NOx concentrations with un-adjusted and adjusted background contributions and the measured NOx concentrations. New Table.2d compares the modelled NO2 concentrations after adjustment of the background contribution with the measured NO2 concentrations. 3. Were the predicted values those originally calculated for G1? No. The model test work (CD1278) for the G1 assessment has not been revised in any way. For the reasons explained in the response to Question 5 below, BAA's consultants considered it prudent to apply the G2 background correction to the G1 assessment. If this background adjustment was applied retrospectively to the G1 model test work then the modelled NOx/NO2 concentration at Stansted 3 would be slightly higher (not lower) than the measured values reported in CD/278. As explained at the inquiry there is evidence showing that the contribution from on-airport sources is being overestimated at receptors close to the airport by the modelling aproach used. 4. If the predicted values were the original G 1 values as shown in Table 19 Vol 3 of the Environmental Statement ('ES) (CD/06) why is it assumed that the background values from the UK national empirical model issued by Defra are too low rather than the predicted airport related values calculated by BAA's consultants? As explained in the answer to question 3 above the predicted values were not the original G1 concentrations as shown in Table 19 Volume 3 of the ES. The model-monitoring differences identified in the letter of 18 February 2008 relate to modelling carried out for the Stansted G2 assessment, for 2006/7. The G1 assessment did not produce values for 2006/7. In the air quality model test carried out in 2008 using 2006/7 monitoring data, the local monitoring sites with data of sufficient quality were grouped into (a) sites affected significantly by on-airport sources (according to the modelling), (b) sites affected significantly by emissions on a nearby major road and (c) sites not appreciably affected by on-airport sources nor by a nearby road'. Group (a) site s This site grouping was also applied to the diffusion tube monitoring sites used in the model test work. The grouping of the continuous monitoring sites was (a) Stansted 3 and 4, (b) Sawbridgeworth Roadside (Cutforth Rd) and (c) Sawbridgeworth Background (Edens Mount), Takeley and Pledgdon Green

3 13244/msp 3rd April were used to examine the modelling in relation to airport sources, group (b) sites to evaluate the modelling in relation to near-road receptors and group (c) sites to evaluate the modelling for the background contribution. It was considered unwise to use sites (c) as a basis for adjusting the modelling in relation to airport and road sources when these sources contributed only a small amount compared to the background ; adjustment, if any, for airport and road-vehicle sources is better made using sites (a) and (b). The 2008 model test work confirms that the contribution from on-airport sources is being overestimated. This is illustrated by the comparision of the modelled and measured concentrations at Stansted 3 and 4 as shown in Table 2c. Sites at risk of exceeding a human-health air quality limit for NO2 are either close to roads or close to airport sources and the performance of the modelling at these categories of receptor is separately evaluated. Sites in Hatfield Forest and Eastend Wood receive a contribution to their annual-mean NOx concentration from the road network as a whole, even though they are not close enough to a particular road to receive a large contribution from it. However, at receptors in these areas, generally the contribution from the network as a whole falls between 2006/7 and the future cases in a similar way to the fall in the background contribution (sometimes a little faster, sometimes a little more slowly), so that representing all of the difference as a fraction of the background contribution would have much the same effect as sharing the difference between the background contribution and the network contribution (for sites that are not close to a road). Thus the model evaluation strategy outlined above is unlikely to lead to significant underestimation in the key areas of interest, and makes best use of the available data. 5. Has Defra accepted that the background data are too low? If so is this only in the GI study area (as defined in ES Vol 3, para and Figure 1) and is it only in relation to NOx or is it suggested that this is wider problem? Please provide us with copies of any correspondence BAA and/or its consultants have had with Defra on this matter. Defra has not been consulted on this point, so there is no correspondence. The Defra modelling is semi-empirical and it is implicit in this type of model - which uses monitoring data for the UK as a whole - that there is uncertainty in the model outputs, displayed in the model reports in terms of the scatter about the fitted line. The aim of the modelling is to develop a relationship between measured concentrations and calculated emissions, to enable forecasts of concentrations to be derived from emissions forecasts with an acceptable level of confidence. The quality criterion against which the model developers judge the fitness of the model is the 30% standard set in the EU Directive, and most data points meet this criterion easily. Thus the model is deemed fit for purpose even though discrepancies can be found at individual sites of up to 30% (of the measured value). The fitting process is repeated on an annual basis. No analysis is repo rted by the model developers regarding whether or not sites in a pa rticular region of the country sit below (or above ) the fitted line consistently from year to year : it is likely that some do and some do not. It requires data on model -monitoring differences over a number of years to establish that there is any systematic effect of this type. Even if such an effect were detected, this would not be considered a failure of the model if the discrepancies were within the target precision of this type of model. At the time of the G1 model test work, the Defra modelling up to the year 2002 was available. BAA's consultants were not aware of any evidence at the time for a systematic under-prediction of the modelling, although it was difficult to find

4 13244/msp 3rd April local sites with adequate data quality. For EH2 (Sawbridgeworth Background), the 2001 version of the model over-predicted by 26% (44.6 tag/m3 model, 35.4 tag/m3 measured) and in 2002 it under-predicted by 12% (26.1 tag/m3 modelled lag/m3 measured). For the local-authority site at Braintree, the model underpredicted in 2002 by 15% (25.9 tag/m3 model, 30.6 tag/m3 measured). Since that time, however, there has been a run of years in which the Defra modelling for NOx has under-predicted at EH2. The average under-prediction over is 28%. Although there is no guarantee that the model will not over-predict in a future year, it was considered prudent for the purpose of the G2 assessment to treat the observed discrepancies at EH2 as a systematic underprediction by the model in the Stansted area and to make an adjustment accordingly. 6. Your letter states (page 2, para 2) that 'comparison at two more distant background sites showed that the model performed within the expected range (±30%) found in the Defra background methodology when compared to the measured values'. Please provide the actual comparative data referred to here. The data referred to have been provided in the response to Question 5 7. Please provide a revised version of Figure 14 (NOx contours for hybrid sensitivity test at 40mppa) as provided in response to the UDC Regulation 19 Notice (CD/145). An updated version of Figure 14 is attached. Although not provided in the Regulation 19 Response (CD/22) the eqivalent NO2 contours are also attached as Figure 14a. 8. Please provide revised versions of Figures 5 and 9 (NO2contours) originally provided in ES Vol 3 (CD/06). Updated versions of Figures 5 and 9 are attached 9. Please provide revised Tables RI and R2 in BAA/4/F/Erratum - originally provided by BAA's witness, Mr Malcolm Pratt relating to the evidence from the measurements recorded by monitoring at Shell House, Hatfield Forest. A revised Table R1 from BAA/4/F/Erratum is attached showing the revised background contributions. Table R2 has also been included for completeness but the measured concentrations shown in this table are not affected by corrections to the modelled background. 10. Please provide revised calculations for the amount of nitrogen deposition in Hatfield Forest to replace those provided by Mr Pratt in BAA/4/A and in BAA/4/D (rebuttal of Mr Moorcroft's evidence (UDC17/A). Revised Tables 4.2, 4.3 and 4.4 from BAA/4/C and referred to in BAA/4/A are attached. Table 4.1 has also been included for completeness but the deposition rates shown in this table are not affected by corrections to the modelled background. The consequential changes to the un-numbered tables from pages 7 and 8 (BAA/4/D) are also attached. The difference in deposition rates between the 25mppa and 35mppa cases is completely unaffected by the adjustment to the background concentrations, although small differences are observed at the level of precision shown in the tables due to rounding and in the calculation of percentage changes. The This was erroneously reported in the G1 model test report as 38.5 µg/m3 because of a typing error in the site co-ordinates

5 13244/msp 3rd April adjusted background increases the NOx concentrations in both cases by the same amount (5 to 6pg/m3). 11. Please provide data to show the variation in annual mean NOx concentration pg/m3) with meteorological data for 2004, 2005 & 2006 in same format as Table 19, ES Vol 3. The revised Table 19 ES Vol 3 (CD/6) for the years 2001 to 2003 is attached. This table has been extended to cover the additional years of 2004 and These data were prepared for the G2 assessement as part of the process used to select the meteorological year for the modelling of the future cases; hence these data were already available. When the selection of the meterological data was made the required 2006 data were not available. The modelling of the future cases is not particularly sensitive to the selection of the meteorological year as can be seen from an inspection of the data in Table 19. Revising and extending the data set to include meteorology of 2004 and 2005 demonstrated that the highest background and airport contributions still arise in The extension of the data set reinforces the decision to adopt 2003 as the basis for the future case modelling. 12. Please provide a revised version of Table 23, ES Vol 3 which corrects the systematic underprediction that is now acknowledged. A revised Table 23 ES Vol 3 (CD/6) for the years 2001 to 2003 is attache d The revisions to Table 23 do not give rise to any exceedance of the NO2 air quality objective. The difference between the 25mppa and 35mppa cases is completely unaffected by the adjustment to the background concentrations, although small differences are observed at the level of precision shown in the tables due to rounding and in the calculation of percentage changes. The adjusted background increases the NOx concentrations in both cases by the same amount (5 to 6pg/m3). As the the conversion from NOx to NO2 is non linear this increase in NOx produces an increase in NO2 of about 2 to 3pg/m3.

6 8 Nea 13244/msp 3rd April 200 Table I Continuous analysers included in the model evaluation Operator ID Name Easting Northing r road Details2 Pollutants Type 3 BAA S3 Stansted N 28 m from centre of minor NON, NO2 C (High House) road PM10 TEO M S4 Stansted N NON, NO2 C (Runway ) UDC U18 Takeley N NON, NO2 C PM10 BAM U21 Pledgdon Green N NON, NO2 C PM10 BA M EHDC EH2 Sawbridgeworth Background N NON, NO2 C (Edens Mount) PM10 TEO M EH3 Sawbridgeworth Roadside Y 8 m from centre of A1184 NON, NO2 C (Cutforth Rd) (7.5 m wide at this point) PM10 TEOM Notes 1 Y' denotes either roadside or kerbside according to standard site classification [Defra (2003) Part IV of the Environment Act 1995 Local Air Quality Management Technical Guidance LAQM TG(03)]. 2 Further information given for near-road sites or to justify non-road statu s 3 'C' denotes Chemiluminescence analyser, 'BAM' denotes Beta Attenuation Monitor and 'TEOM' denotes Tapering Element Oscillating Microbalance

7 13244/msp 3rd April Table 2a Continuous NO,/NO2 analysers : data characteristics Ratificatio n Data Longest missin g Period mean (µg/m ) ID Site name Status ' capture % period (hours) NO, NO 2 S3 Stansted 3 R (Jul 06) S4 Stansted 4 R (Jun 06) U18 Takeley R (Aug 06) U21 Pledgdon Green R/P (Dec 06) EH2 Sawbridgeworth Background R/P (Nov/Dec 06) EH3 Sawbridgeworth Roadside R/P (Jan 07) Notes 1 R - ratified; P - provisional 2 Ratified for 2006 ; provisional for ratified until 17/01/07; provisional thereafte r Table 2b Comparison of un - adjusted modelled NO. concentrations with measured values : continuous NOx/NO2 analysers ' ID Site Name Modelled NOx Concentration (µg/m ) Measured NOx Concentration ( µg/m3) Ratio 2 S3 Stansted S4 Stansted U18 Takele y U21 Pledgdon Green EH2 Sawbridgeworth Backgroun d EH3 Sawbridgeworth Roadside Notes 1 All values shown to two decimal places to avoid the accumulation of rounding errors in forming ratios ; this is not indicative of the precision of either the model or measured values 2 Ratio is model value divided by measured value.

8 13244/ms p 3rd April Table 2c Comparison of background- adjusted model NO, concentrations with measured values : continuous analysers ID Site Name Modelled NOx Concentration ( µg/m3) Measured NOx 3 Concentration (µg/m Ratio2 S3 Stansted S4 Stansted U18 Takeley U21 Pledgdon Green EH2 Sawbridgeworth Background EH3 Sawbridgeworth Roadside Notes I All values shown to two decimal places to avoid the accumulation of rounding errors in forming ratios ; this is not indicative of the precision of either the model or measured values 2 Ratio is model value divided by measured value. 3 For the G2 modelling a further adjustment at this near road receptor in a built up area was applied. EH3 was outside the G1 study area. Table 2d Comparison of NO2 concentrations and NO2/NOx ratios at non-road continuous analysers Modelled NO2 Measured NO2 ID Site Name Concentration Concentration Ratio2 (µg/m3)1 (µg/m3 ) S3 Stansted S4 Stansted U18 Takeley U21 Pledgdon Green EH2 Sawbridgeworth Background Notes 1 Model values based on background-adjusted NOx values 2 Ratio is model value divided by measured value.

9 13244/msp 3rd April Table RI Modelled Nitrogen Oxide Concentration Contributions at Shell House Case Background Aircraft etc Airport related road traffic Model test 23rd October 03 to 18 th May Non-airport related road Total road traffic' Total all sources2 traffic Measured concentration 16 Jan 04 to 04 Jun mppa mppa Notes I Sum of columns 4 and 5 where available 2 Sum of 2, 3, and 6 3 Data provided by Dr Haycock Table R2 Measured Concentrations at Monitoring Sites on Specified Dates (from Figure R2 ) Date t i me Shell H ouse Takeley Runway (S4) High House (S3) Sawbridgeworth (EH2) 28th March th April th April th April th April th April

10 13244/msp 3rd April Table 4. 1 Reference Deposition Rates (APIS) [not affected by changes to modelled background ] Receptor ( a ) Critical Total N Percentage (b) Forecast Percentageibi Reduction Averag e load deposition exceedence of Total N exceedence in N reductio n range ( critical load in deposition of critical deposition in N ( kgn/ha/y) 2001 ) 2000 (2014 ) load in 2014 ( kgn/ha ) depositio n (kgn/ha/y) (kgn / ha/y) per yea r (kgn/ha/y) Hatfield Forest % % (553200, ) Eastend Wood % % (555800, ) Notes: (a) the selected receptors are just outside Hatfield Forest and East end Wood (See Figure 4.2 Volume 3) (b) Calculation based on a representative critical load value of 12kqN/ha/y as adopted by CEH (2007) U K National Focus Centre for critical loads modelling and mappin g Table 4.2 NOx and NO2 Concentrations from the GI Air Quality Assessment (kgn/ha/y) NOx concentration Ratio Total NO2 concentration (µg/m) airpo r t/total (µg/m ) Receptor ( a) Case Total Airport NOx ES Regulation 19 assessment Sensitivity test Hatfield Forest 25 mppa (553200, ) 35 mppa Eastend Wood 25 mppa (555800, ) 35 mppa Notes: (a) the selected receptors are just outside Hatfield Forest and East end Wood (See Figure 4.2 Volume 3) Table 4.3 Calculated Deposition Rate - ES Assessment ES Assessmen t Receptor ( a) Case N deposition rate N deposition rate Airport % of total from total NOx from airport NOx N deposition (kgn/ha/y) (kgn /ha/y) Hatfield Forest 25 mppa mppa Difference Eastend Wood 25 mppa mppa Difference Notes : (a) the selected receptors are just outside Hatfield Forest and East end Wood (See Figure 4.2 Volume 3) 3 Extracts from CEH (2007) UK National Focus Centre are provided in Appendix XIII

11 13244/msp 3rd April 2008 Table 4.4 Calculated Deposition Rates - Regulation 19 sensitivity tes t Regulation 19 Sensitivity test Receptor ( a) Case N deposition rate N deposition from Airport % of tota l from total NOx airport NOx N depositio n (kgn/ha / y) (kgn /ha/y) Hatfield Forest 25 mppa mppa Difference Eastend Wood 25 mppa mppa Difference Notes : (a) the selected receptors are just outside Hatfield Forest and East end Wood (See Figure 4.2 Volume 3 ) Unnumbered table on Page 7 / 8 of BAA/4/D mppa Estimated Airport Contribution to N Deposition fl ux (kgn/ha/y) Base Sensitivity Hatfield Forest Difference Percentage increase Eastend Wood Difference Percentage increase Unnumbered table on Page 8 of BAA/4/D Airport Contribution to N deposition (%) mppa Base Sensitivity Hatfield Forest Difference Eastend Wood Difference

12 13244/msp 3rd April Table 19 : Variation in Annual Mean NOx Concentration (lag/m3) with Meteorological Data from , 2003, 2004 and 2005 Met Year X Y Site Name NOx Background NOx non - airport roads Total airport - re lated NOx Tota l High House Takeley Landing Lights Balancing Pond Highfield Lodge Molehill Green Bamber Green Old House Farm" Thremhall Farm Tilekiln Green Bury Lodge Bu rton End Tye Green Motts Hall High House Takeley Landing Lights Balancing Pond Highfield Lodge Molehill Green Bamber Green Old House Farm Thremhall Farm Tilekiln Green Bury Lodge Burton End Tye Green Mott's Hall High House Takeley Landing Lights Balancing Pond Highfield Lodge Molehill Green Bamber Green Note 1 : The receptor name should be Le Knell's Cotta ge, not Old House Farm as was shown in th e original table 19. This same note applies to Table 23.

13 13244/msp 3rd April Met NOx non - Total NOx Back - NO x X Y Site Name airport airport- Year ground Tota l roads relate d Old House Farm Thremhall Farm Tilekiln Green Bury Lodge Burton End Tye Green Mott's Hall High House Takeley Landing Lights Balancing Pond Highfield Lodge Molehill Green Bamber Green Old House Farm Thremhall Farm Tilekiln Green Bury Lodge Burton End Tye Green Mott's Hall High House Takeley Landing Lights Balancing Pond Highfield Lodge Molehill Green Bamber Green Old House Farm Thremhall Farm Tilekiln Green Bury Lodge Burton End Tye Green Mott's Hall

14 13244/ms p 3rd April Table 23 : Modelle d case Modelled Annual Mean NOx (and NO2) Concentrations (pg/m3 ) Arising from the 25 mppa and 35 mppa Cases X Y Site name Background Non-airport roads Total airport - related Tota l NOx NO2 25 mppa case % of AQS (40pg / m3) 25 mppa High House % Takeley % Landing Lights % Balancing Pond % Highfield Lodge % Molehill Green % Bamber Green % Old House Farm % Thremhall Farm % Tilekiln Green % Bury Lodge % Burton End % Tye Green % Mott's Hall % NO z difference 35 mppa High House % incremen t as /o % of AQ S Takeley % Landing Lights % Balancing Pond % Highfield Lodge % Molehill Green % Bamber Green % Old House Farm % Thremhall Farm % Tilekiln Green % Bury Lodge % Burton End % Tye Green % Mott's Hall %