Feb 9 (Reuters) - Waste disposal company Republic Services Inc said on Wednesday it would buy smaller rival US Ecology Inc in an all-cash deal valued at $2.2 billion, including net debt.

Republic's offer of $48 per share represents a 70.4% premium to US Ecology's last close on Tuesday.

The deal would help Republic boost its customer base and expand across the United States and Canada, the company said. It would also add to its adjusted earnings and free cash flow.

Shares of US Ecology surged 67% in pre-market trade, while those of Republic remained flat.

Republic said it intends to finance the deal using existing and new sources of debt.

(Reporting by Aishwarya Nair in Bengaluru; Editing by Ramakrishnan M.)