An underground storage tank will be used to protect parts of Dorchester from flooding and sewage pollution.

It will be put into place under the Great Field in an operation which is expected to take six months to complete.

The extra protection is based on computer modelling by Wessex Water of the risks brought about by the final phases of building at Poundbury.

A briefing about the project will be held tomorrow.

However, the Echo now understands this is a private meeting, by invite only, and is full.

However a public drop in session is being held next Tuesday, December 10 at The Quiet Space in Poundbury. Wessex Water will be there from 10am to 7pm.

The chamber will be close to the corner of St John Way and Peverell Avenue East with some equipment and a hard standing and manhole covers being visible above ground.

The pumped return storage tank for sewage is needed for additional storm storage to help protect Dorchester town centre and the River Frome.

Wessex Water say when it modelled the effect of the final 645 houses in the last phases of Poundbury it discovered a heightened risk of flooding and a possible increase in combined sewer outfall spills at several locations in Dorchester town centre which could result in additional spills of raw sewage into the River Frome.

Their solution is to add a 450 square metre pumped return storage tank to the system under the Great Field, linking in to the nearby existing sewer network. The tank itself will be 10.5 metres in diameter with an above ground kiosk 1.8 metres tall to control the pumps.

Wessex Water say that on completion, the development will not create any additional traffic movements other than periodic maintenance visits, and tankers in the unlikely event of an incident.

The works are the final phases of the sewage network for the area.

Wessex Water say it will create a hardstanding area off St John Way and a temporary construction compound on the Great Field which will be removed when the work is finished.