But an emergency site visit by Environment Agency officers last Tuesday found it was Biffa's failure to control the release of landfill gas that caused the pong. Biffa had to file an "urgent" action plan to the agency by last Friday. But with the return of the smell yesterday, continuing today (Thursday), there have been dozens more complaints. Biffa has so far declined to say what is in the action plan. A spokeswoman told the Mirror this afternoon: "The action plan has been submitted and we are working to the timescales agreed with the Environment Agency. "The action plan contains details for the installation of additional gas infrastructure around the operational areas of the landfill site." Biffa has not yet said when the work will be done, or when residents can expect some relief. During last week's probe, Environment Agency officers found landfill gas odour emanating from five different areas.
They detected raised levels of methane in one, and could see gas visibly rising from the landfill.
In one cell, currently being used to dump Surrey's rubbish, they were told no gas infrastructure – to capture the odour – was in place.
They also found a sewage stench caused by contaminated water running down a slope in one part of the site.
Biffa was issued with a warning and ordered to "adopt a more robust proactive approach to minimise the risk of a similar event occurring".
Environment Agency investigators were called in last Tuesday after more than 75 complaints about the smell.
Spokeswoman Elisa Orchard said: "During an on-site investigation, Environment Agency officers found that contaminated surface water was causing a sewage-like odour in one area of the site and that methane gas emissions were not being effectively managed in specific locations, including the current operating cell. We have produced a report of our findings and Biffa have agreed to review their odour management and gas management plans.
"We are carrying out regular odour assessments and further site inspections and we will continue to monitor progress with the remedial actions over the coming weeks.
"We encourage local residents to continue to call our 24/7 incident hotline on 0800 807 060, should they continue to experience odours."
The Environment Agency has so far not provided the Mirror with any comment in relation to this week's odour outbreak. Biffa has apologised for the inconvenience caused.
