Failed environmental offset on new bypass

I just read about how a recent bypass project in the UK came with a significant spend on environmental investment. This spend seems to mostly have been trees, ponds and culverts. This investment in trying to make the environment alongside the new road better (I presume better for wildlife) will have certainly contributing to the project being approved.
A few years after the road opened - most of the hundreds of thousands of trees died before getting past the sapling stage and the ponds and culverts are choked with litter and dried mud. In short, completely failing to achieve the promised environmental benefits.
What is going on here? It is very difficult and expensive to build new roads in the UK - mostly there is no empty space so compulsory purchase is needed and destroying existing habitats is inevitable. In getting the approval with these environmental promises did the agency building the road think “job done, chuck in a ton of trees and walk away”? Was this lip service to their promise? Or did the agency actually not understand what was involved in establishing and maintaining new habitats?
Or would the money have been better spent on something other than a bypass?

This is so typical of todays “couldn’t care less” attitude or “not my department” buck passing. Even if an inquiry is started it can take years to produce a report full of useless information, nothing to do with the subject. I put 90% of the blame on employing university graduates who have never done a days work in their lives, (got a degree in knitting or similar) and get high powered jobs they know nothing about

Sounds like a good, well intentioned idea, but a poor implementation. Projects like that fail because of bad management.

Looks like all those trees dried up in a hot summer. I suppose they are reliant on nature to provide the basics. If the ground is just churned up subsoil and rubble on a slope not much is going to grow apart from weeds. Contractors must be experienced in this so there must have been skimping and a lack of follow up care. Although the farmers manage to water their crops. Maybe they just spoiled the ship for a ha’porth of tar!

It certainly looks like that. Although, if this was really a ground breaking standard of environmental offset, then there is a good chance that the contractors were new to such a project. So the lack of follow up care may simply have been because they did not know. Or be aware enough to think to ask someone who did know.

Not enough advice available in this field in the Cambridge area, I suppose.