Manchester's most significant corporate development has been praised by independent inspectors for the responsible way it is being conducted. And it owes its success partly to a biological feature which is usually treated as contamination.

An independent inspection of The Co-operative Group's new head office in central Manchester gained over 96% (38.5 out of 40 points awarded) from the industry's Considerate Constructors' Scheme (CCS). The score places the project ahead of more than 99% of the 60,000 project site inspections during the Scheme's 12-year history.

The Co-operative head office project - being constructed by Salford-based BAM Construction - scored five maximums in eight categories such as how it manages the environment, how clean it is, its attitude to neighbours, its respectfulness and responsibility to the workforce.

Most unusual of the measures established by the team is a water feature that has been set up after finding an infestation of Japanese Knotweed. The plant, whose removal is covered by the Wildlife and Countryside Act 1981 and requires a licence - has its native environment on the slopes of volcanoes. It was discovered near the main entrance, treated by workers, then landscaped rather than fenced off and converted into a water feature. The project team and visitors to the site now treat the feature as a wishing well. The inspector praised the "delightful" innovation which he said is raising "significant" contributions towards the project's £25,000 target for donations to charity.

Other initiatives include: a "meet the builder" day and a cheese and wine evening for neighbours; a weekly visit from a nurse to carry out health screening for the workforce; and extensive arrangements to keep the site looking professional leading the inspector to comment that "the site is amazingly clean and tidy, cleanliness is excellent". The CCS inspector wrote 'there are so many good things to report it was hard to include everything' and 'have an active desire to raise the bar'.

Tony Grindrod, construction manager of the Co-operative Group's contractors, BAM Construction, said:

”For BAM this is not just another construction project, it is chance to use our time here to do something truly positive for people in Manchester. We're being encouraged by our ambitious client, who has strong social values and this is bringing the best out of our team who are not only willing but are very active partners in the community.”

The project has numerous employment initiatives which also impressed the inspectors such as its work with apprentices who are extensively engaged in helping to refurbish the Headquarters of Lifeshare, the voluntary organisation for the young homeless, allowing them to gain valuable work experience.

Martyn Hulme, Managing Director of The Co-operative Estates, said: “BAM should be congratulated on setting such exemplar standards for how construction projects should be run.

“These outstanding scores from independent inspectors underline to what extent BAM is integrating a high degree of social awareness, consideration for neighbours and responsibility and welfare for onsite operators.”

The project cannot bank the score and rest on its laurels, however. The CCS inspectors will be back when it is further into its programme when the BAM and The Co-operative teams will need to do even better to maintain their outstanding rating.