Neil Kirkby, finance director of Enterprise, said that a price had not been finalised for the firm, but added that the buy showed it was in the market for acquisitions.
"Over the past two or so years we have made a few acquisitions – this is us starting that again. I don't think this will be the last buy."
Kirkby added that the acquisition would improve Enterprise's coverage in the south, where Subterra largely operates. Subterra's support offices, which include administration and accounts departments, are based in Preston, which is near Enterprise's base in Leyland, Lancashire.
Enterprise's work with local authorities includes highways and grounds maintenance, and its public sector work focuses on building maintenance.