Private equity and infrastructure investment firm First Reserve is to acquire Morrison Utility Services, anticipating the deal to close by November.
Financial terms were undisclosed and the transaction is subject to regulatory approval.
The company posted turnover of £585m for the financial year to 31 March 2015.
According to its current private equity owners, the revenues now top £600m.
The firm has numerous contracts with energy, water and telecoms companies to provide maintenance and infrastructure works. It also owns a connections business.