Two of Somerset's main quarries could both close their doors by 2040, putting dozens of local jobs at risk.

Somerset County Council has published its local aggregates assessment (LAA), which sets out how many years' worth of reserves are left in the county's various quarries.

The county currently exports large quantities of limestone and other materials to London and the south east for construction projects, with a substantial percentage being transported by rail from two sites located between Shepton Mallet and Frome.

But the planning permissions governing both quarries will both expire within the next two decades – putting jobs at risk and having repercussions for major infrastructure projects across the UK.

An update on the LAA came before the council's environment scrutiny committee when it met for the first time in Taunton on Wednesday morning (September 28).

Somerset quarries produce two main types of crushed rock – carboniferous limestone (which is used to produce concrete and other building materials) and silurian andesite (also known as basalt, which is used to produce skid-resistant road surfaces).

Mineral extraction is currently responsible for the equivalent of 1,000 full-time jobs across Somerset (across aggregates, quarry products, building stones and stone-masonry), generating around £135m to the economy in 2019 (the most recent figures available).

The county council's minerals plan seeks to ensure that Somerset always has at least 15 years' worth of quarry-able material available, spread over the following approved sites:

• Batts Combe Quarry, Warren Hill, Cheddar
• Callow Rock Quarry, Shipham Road, Cheddar
• Cannington Park and Castle Hill Quarry, Stradling's Hill, Cannington
• Chard Junction Quarry, Station Road, nr Tatworth
• Gurney Slade Quarry, Tape Lane, Gurney Slade
• Halecombe Quarry, Limekiln Lane, Leigh-upon-Mendip
• Moons Hill Quarry, Mendip Road, Stoke St. Michael
• Torr Works Quarry, A361, nr East Cranmore
• Whatley Quarry, Knapton's Hill, Mells

Out of every 100 tonnes of stone quarried and extracted in Somerset, 26 tonnes is exported to the south east (mainly to Berkshire and Essex), with a further 12 tonnes going to London.

A total of 40 per cent of Somerset's crushed rocks is transported by rail from two quarries – Torr Works and Whatley.

A spokesman said: "While the current land-bank for crushed rock in Somerset is 27.1 years, the planning permission end dates of the two main rail-linked quarries, Whatley Quarry and Torr Works, are due to expire in 2030 and 2040 respectively.

"This has implications for the ability of crushed rock worked in Somerset to meet future demand for crushed rock in the London and the south east."

Stone quarried within Somerset is in high demand for nationally significant infrastructure projects, including the dualling of the A303 near Stonehenge, the new Heathrow Airport rail link, High Speed 2, the next phase of Crossrail and the Sizewell C nuclear power station in Suffolk.

A spokesman said: "Even if some of these projects are not supplied by crushed rock from Somerset, they will likely have knock-on effects which will create ongoing demand for crushed rock from Somerset."

Closer to home, the materials quarried in Somerset will be used on major infrastructure projects across the south west – including the planned dualling of the A358 between Taunton and Ilminster, the Gravity smart campus near Brridgwater and the planned expansion of Bristol Airport.

The council said the future of both Torr Works and Whatley will be considered during an upcoming review of its minerals plan.

A decision is also expected in the coming months over plans to reopen Westdown Quarry, which would focus on supplying construction projects in Somerset while the nearby Whatley Quarry focussed on exporting products to the south east by rail.

Councillor Kathy Pearce, who represents the Bridgwater South division, said any decisions over reopening or closing quarries should be done with one eye on tackling climate change.

She said: "Has there been any work done on carbon emissions from this industry? At some point I'm guessing we'll need to look at Somerset as a whole to have a baseline if we're working towards reducing carbon emissions."

Colin Arnold, the council's service manager for planning and development, responded: "I don't know if it's directly been done in terms of quarries, but it's definitely something we can look at."