Anglian Water hits back at claims newly-planted trees at proposed sewage works won’t survive

Anglian Water has pledged that there will be no repeat of the A14 tree deaths seen when it plants around its proposed new sewage works.

Tens of thousands of trees planted during the project to upgrade the A14 swiftly perished, it emerged.

But Anglian Water has hit back at claims the trees it plans to plant on top of an embankment around a relocated Cambridge Waste Water Treatment Plant will not survive without long-term watering.

Representatives said they understood concerns in the area following the issues with the National Highways tree planting scheme, but said their plans would ensure a “very different situation”.

The discussion came during last week’s hearing about Anglian Water’s Development Consent Order (DCO) application, requesting permission to build the new sewage works on land north of the A14 between Fen Ditton and Horningsea, known as Honey Hill.

The new facility, if given approval, will replace the existing sewage works in the north of Cambridge, which will free up the land it sits on for 8,000 homes in the North East Cambridge development.

At the DCO hearing, Alex Hudson, one of the Planning Inspectorate’s examiners, said: “Numerous concerns around the likely success of planting on the bund have been raised, primarily due to the dryness area and the potential need for watering in perpetuity. If constant watering is needed, how does this represent a sustainable design solution?”

Jo Morrison, representing Anglian Water, said detailed plans had been prepared for the tree planting and to look after them as they establish.

She said they planned to make sure the soil was of good enough quality to make a “good growing medium” on the embankment.

Ms Morrison was aware Cambridge is “very dry and is getting drier”, but said the embankment would hold some of the rainwater.

She also said they were choosing species that already grow in the area, and explained how they would be watered and looked after in the first five years to make sure they get a “sufficient good root system to be able to withstand seasonal droughts”.

Ms Morrison added that if any trees did die, then they would be replaced, potentially with a species more likely to survive.

However, a representative of South Cambridgeshire District Council still had concerns, saying in the council’s experience trees did not thrive when planted on top of bunds in the area.

The water retained in the embankment’s soil would not be the same as at ground level, the representative warned, adding that in a drought period the trees on an embankment would have to go longer without water unless they are watered, which raised the sustainability questions.

Ian Gilder, from the Save Honey Hill campaign group, said he had been planting trees in the area for 30 years and had seen the impact of drier seasons.

He warned: “I think it is pretty clear that without sustained watering, or opportunity to intervene in dry conditions that it is very unlikely that those trees will thrive.”

Mr Gilder highlighted that growing the trees on top of the bund was intended to screen the view of the new sewage works. If the trees did not grow well or survive, they would not create the screening they are intended to provide, he noted.

Liz Cotton, who lives near to Honey Hill, noted there sas “all this talk of screening, having to cover up something ugly” while “losing something beautiful”.

“With all the screening in the world, it is not going to bring that back,” she said.

Andrew Prior, representing Anglian Water, understood the concerns after the A14 experience but promised: “Here there is a soil management plan and the ability to water during the establishment period, and this embankment has a broad high top. It is not the same as a highway embankment.

“We believe the trees will establish and establish well. We can provide more evidence on that, but there are also substantial examples planting on well tended embankments that shows that is the case.

“I do not think we really agree with the characterization that these trees will die after five years. We have made very detailed efforts to make sure they will establish.”

The district council representative said there may be examples of trees growing on top of embankments in other parts of the country, but said this region “is the driest in England”, adding that trees on slopes did not grow well in the area.

The representative added that it was not just the “highways experience” that gave cause for concern, as it was also happening elsewhere, including at housing developments, where trees were not surviving.