An extension to a Purbeck quarry is being recommended for approval by Dorset Council.

It comes despite around 70 letters of objection claiming that a larger Swanworth Quarry at Worth Matravers would be too intrusive and damaging to wildlife.

Owners, Suttles Stone Quarries, say they will devote more of the adjacent area to nature conservation with funding of £10,000 a year to enhance biodiversity.

The company is asking for a 14 hectare extension to the existing 37 hectare site, retaining the existing processing plant and to be allowed to more import inert waste to restore quarried areas.

More than 100 letters were sent to Dorset Council supporting the changes, including from Corfe Castle parish council.

If the extension is allowed it will see 2.4 million tonnes of limestone extracted at the rate of 125,000 tonnes a year over 20 years with 75,000 tonnes of inert waste a year brought onto the site.

The quarry is within the Dorset Area of Outstanding Natural Beauty and the Purbeck Heritage Coast and is just over 1 kilometre from the Jurassic Coast World Heritage Site.

Said one letter of objection: “It takes many years to establish wildlife habitats and to destroy them at a time when we are all trying to save and treasure our environment would be to go against the preservation of the health and wellbeing of our future generations.”

In response to environmental concerns Suttles are proposing 12ha of biodiversity habitat enhancements alongside the existing quarry, including more than 5ha of calcareous grassland with a 30-year biodiversity management scheme for the whole site.

Dorset Council’s strategic planning committee, which meets on November 21, is being recommended by officers to approve the extension.

An officer report tells councillors: “Due to the scale, extent and duration of the proposed development, there would be some harm to the special qualities of the AONB. However, the development would ensure an adequate and steady supply of aggregate and waste management provision in a suitably sustainable manner to meet local needs and would provide valuable support to the local economy as a source of stable employment and in influencing local supply chains.”

At full capacity, Suttles’ Swanworth site is able to supply around half of Dorset’s required crushed stone needs.

Ward councillor Cherry Brooks has backed the extension, telling officers she fully supports the need to protect the environment and the AONB, but says that needs to be balanced with the threat to the local economy.

“Swanworth Quarry has been operating for a very long time and although the extension would cause disruption, there would be improved habitat upon restoration based on the operator’s track record so far which has exceeded expectations,” she said.

The application includes the construction of a five-metre tall bridge across Coombe Bottom and the Purbeck Way path to access the extension and allows for a seven-year restoration period for the extension and the existing quarry.

The entrance to Swanworth Quarry is about 460 metres (m) south of the B3069 on the western side of Kingston Lane that leads to Worth Matravers about 900m to the south.