Aggregate Industries has messed up its numbers again.
In DCC’s Regulation 22 request – now over a year ago – the Council wanted to know:
In terms of sustainable transport the relationship of the processing site to the markets needs to be considered as does the alternative of not implementing this site which could mean that all high PSV aggregate was imported from elsewhere. Reason: To demonstrate compliance with Policy M12 of the Devon Minerals Plan. 8.3
Earlier, in its Supporting Statement, AI had claimed that because of Straitgate’s location, and its crushable gravel content, the site represented the most sustainable supply of high polished stone value material for the Rockbeare and Westleigh asphalt plants:
The gravel content [at Straitgate] is important as it is capable of producing a 57 PSV aggregate suitable for road surfacing. 5.4.5
Highways England demand that the Devon’s major trunk roads are surfaced with nothing less than a 57 PSV aggregate. 3.9.4
AI claimed Straitgate was needed because at the company’s current 4 million tonne sand and gravel reserve at Houndaller – the one with quartzite pebbles stockpiled all over the place – the one next-door to Hillhead near Uffculme, where Straitgate’s material would be taken for processing:
... there is little or no crushable gravel to produce a 57 PSV aggregate. 3.9.2
How much high PSV material does AI need in Devon? AI’s Regulation 22 response claimed that Rockbeare needed 12,000 tonnes pa and Westleigh 35,000 tonnes pa 8.2.
Where else could supply it? In answer to DCC’s Reg 22 point above, AI said:
The alternative supply of high PSV aggregate for the Westleigh and Rockbeare asphalt plants would come from the applicant’s operation at Greystone Quarry in Launceston, Cornwall. 8.3
Isn’t Greystone further away? Yes, it’s just the other side of the Devon border. AI was happy to say that the total distances for processed mineral to reach the Rockbeare and Westleigh plants from Greystone, and the increase this would represent compared with material sourced from Straitgate, would be:
Greystone to Rockbeare = 55.6 miles = 9.4 miles increaseGreystone to Westleigh = 70 miles = 40.0 miles increase 8.3
But intentionally or not, AI has got its numbers wrong. It is not comparing like with like. Processed material may come from Greystone, but processed material would not come from Straitgate. In fact, as-dug material would be transported from Straitgate to Hillhead. It would contain 20% waste. Of the remaining material: 54% would be gravel, of which – according to DCC – 26% is "the proportion of the gravel that is crushable".
i.e. Each 28.5 tonne as-dug load from Straitgate would entail a round trip of 46.8 miles for 28.5 x 0.8 x 0.54 = 12.3 tonnes of gravel, of which 12.3 x 0.26 = 3.2 tonnes would be crushable for high PSV material. Or, to put it another way, to reach a processed state comparable with Greystone material: 28.5 tonnes of high PSV material from Straitgate would entail (28.5/3.2) x 46.8 = 417 miles of transportation.
With return distances from Hillhead to Rockbeare of 46.8 miles and to Westleigh 8.8 miles, one 28.5 tonne load of Straitgate high PSV material supplied to Rockbeare would effectively have to travel 464 miles, and to Westleigh 426 miles.
In other words, high PSV material from Straitgate would have to travel over 3x the return-trip distance of material from Greystone!
AI is therefore completely wrong – as it so often is – to say:
It can therefore be concluded that supplying Westleigh/Rockbeare asphalt plants with high PSV crushed stone mineral from Straitgate is a more sustainable option than it would be from alternative sources outside of Devon. 8.3
The importance and sustainability of Straitgate has therefore been misstated. Even more so when you consider, not only the 4 million tonnes of sand and gravel at Houndaller, but that last year AI won an extension to Greystone Quarry giving it another 10 million tonnes of high PSV aggregate – enough to supply Rockbeare and Westleigh for over 200 years!
AI is not short of aggregate, high PSV or otherwise. No wonder, it’s in no hurry with Straitgate.
Clearly, "the alternative of not implementing this site" would be the most sustainable option.
