UPDATE ON LOCAL ODOUR ISSUES
The Sherford Consortium has taken proactive steps to investigate and address any contribution that Sherford's infrastructure may make to local odour issues. All investigations, expert consultants, and associated works have been commissioned and funded by the Consortium, clearly demonstrating its own commitment to getting this right.
Historic odour issues in the wider Plympton area are likely to have multiple contributing causes.
The Consortium can only speak about its own infrastructure, and investigations have identified that incoming sewer flows to Sherford's pumping station are contributing to a localised odour issue at the junction of Ridge Road and Merafield Road, which the Consortium is moving swiftly to address.
What the investigations found
Over the past two months, investigations have been carried out by independent specialists commissioned by the Consortium to test and analyse the infrastructure from Sherford to the Marsh Mills Sewage Treatment Works.
The report, delivered at the end of June, showed that there are neither significant structural issues nor blockages in the system, however some septicity was identified in wastewater entering Sherford's pumping station.
The specialists recommended a dosing regime to treat the waste, alongside minor adjustments to the wet well, the underground chamber that temporarily holds wastewater before it is pumped onwards, and modifications to the rising main, which is the pressurised pipeline that carries waste through the system, to ensure sewage moves through at greater speed.
The consultants have confirmed that such issues are common and can be fully resolved.
What is being done
Acting on the consultants’ recommendations, the Consortium is implementing a series of changes, with work commencing this week. These measures are designed to deliver immediate benefits and mitigate the odour.
A new regime of chemical dosing at the wet well will neutralise odour at source, followed by a programme of additional cleaning. Modifications to the rising main, moving from two active pumps to one, will significantly increase the pressure and speed at which waste travels through the infrastructure, reducing retention time within the rising main by half. A further stage of chemical dosing at this point will provide additional odour control.
Sherford's pumping station has been monitored around the clock by a specialist maintenance contractor and this will continue. The expert consultants will return to carry out a follow-up assessment, with a report expected in mid-August to confirm the improvements are working as intended.
The broader picture
The sewers and pumping station at Sherford have been built in line with designs approved by South West Water. The sewage network and pumping station are progressing through the adoption process to transfer into South West Water's control. The Consortium continues to meet with South West Water monthly and maintains a close and collaborative working relationship with them.
