Technical and Strategic Assessment of Aggregate Supply Options in ...

Technical & Strategic Assessment of Aggregate Supply Options in the South West RegionTable 4.9: Comparison of estimates for the re-use, recycling and disposal of hardconstruction, demolition and excavation arisings in the South West with comparableestimates for England as a whole in 2003IndicatorSW as % ofEnglandRecycled aggregate and soil 11.2 %Material used for landfill engineering or restoration 10.4 %Material used to backfill quarry voids 7.1 %Material used at Para 9&19 registered exempt sites 14.7 %Material disposed of at landfills 9.5 %All CDEW 11.0 %Regional population 10.0 %Regional Gross Value Added 8.9 %4.68 The conclusion from these comparisons is that the estimates for the South West are verymuch in line with reasonable expectations.4.69 As with all survey results, these estimates come with a degree of uncertainty, however. Forthe most important figure (Hard C&D / excavation waste crushed and/or screened for useas aggregate) the estimate is 4.47 million tonnes ± 17 % at a confidence interval of 90 %.This is equivalent to saying “based on the data collected, there is only a 1-in-10 chance thatthe true figure is less than 3.71 million tonnes, or more than 5.23 million tonnes”.Sub-regional Breakdown4.70 In all statistical surveys, the smaller the sub-groups into which a population is split, the lessprecise the estimates for those sub-groups become. This is particularly true for a materiallike recycled aggregate, which is predominantly produced using mobile crushers. Bothdemolition waste for processing and the mobile crushers which process it crossadministrative boundaries in the course of normal business. Since the typical traveldistance is no more than 15-20 km, the impact of such movements on regional estimates isnot particularly severe. Within regions, however, such impacts are greatly magnified.4.71 This is exemplified in the case of the South West region by the influence of the Mendipregion, which is home to several relatively large fleets of mobile crushers, some of whichwork wholly or mainly in quarries, some of which work both in quarries and with demolitionwaste, and some of which work wholly or mainly with demolition waste.4.72 The survey carried out by Capita Symonds for ODPM contacted the operators of 97 preidentifiedcrushers based within the South West, and replies were received from 59 of these(a response rate substantially above the national average). Once non-recycling activity hadbeen taken into account, it was concluded that the equivalent of 89 recycling crushers wereactive in the South West.4.73 The survey provided good evidence that crushers in urban areas (defined as those with apopulation density greater than 1,000 persons per square km) have throughputs almost20 % higher than those in rural areas. However, with more crushers active in rural areas,the average production per capita was higher in rural than in urban areas (though this isdue in part to urban demolition waste being processed in less densely populated areas ofurban fringe). This distinction between urban and rural areas was central to the way inwhich the estimate of 4.47 million tonnes of recycled aggregate in the South West wascalculated.Capita Symonds Limited page 21 June 2005