CH2M has seconded 37 members of staff into HS2, the government has revealed.
Transport minister Andrew Jones confirmed to parliament that 37 people were currently on secondment at the client for the £55.7bn rail-link project from the US engineering giant.
His response to a question from Chesham and Amersham MP Cheryl Gillan also revealed that 25 of HS2’s current staff members had previously worked for CH2M.
In total there are 84 CH2M members of staff currently working in HS2’s offices, according to Mr Jones.
CH2M secured the £70m HS2 phase one development partner role in 2012 and – as part of a JV with Atkins and Sener – bagged the £350m phase one engineering delivery partner role in March 2016.
The US firm was then awarded the £170m development partner contract for phase 2b of the line last month, beating Bechtel and a JV of Mace and Turner & Townsend to the contract.
CH2M was expected to officially sign that deal last week, but this was postponed and a meeting was set up between the client and Mace.
The latest award came amid concerns over a conflict of interest after former CH2M European managing director Roy Hill was appointed interim chief executive of HS2 during the procurement process for the contract.
Mr Hill himself was seconded to HS2 from CH2M.
HS2 said it had carried out its most robust procurement process for the phase two development partner award, including getting assurances from CH2M that it would enforce a Chinese wall between its bid team and its employees already working for HS2.
A meeting between Mace and HS2 is understood to have taken place this week, with HS2 responding to a series of questions from the contractor over the procurement process.
HS2 was not able to answer questions from Mrs Gillan on the number of people who returned to CH2M after working for HS2.
HS2’s new chief executive – former CH2M European managing director Mark Thurston – is understood to have started his role earlier this week.
An HS2 spokesman said: “In line with HS2’s collaborative approach to developing the programme with its suppliers, it is common for employees across HS2’s contractors to spend time working in HS2.
”Where necessary provisions are put in place to protect the integrity of HS2’s procurement processes.
”Recent examples of this have included anonymising the bid process for our Phase 2b development partner contract and the exclusion of individuals from discussions, documents and decision making as a precautionary measure.”