Trident Health System won state approval Wednesday to build a $27 million, 30-bed expansion of its Summerville Medical Center.

But Trident’s competitor, Roper St. Francis Healthcare, almost certainly will fight the approval in the coming week, a Roper official said.

Trident, owned by national hospital chain HCA Inc., received initial approval in June to build a three-story “patient tower” at its existing 94-bed Summerville facility.

“...The project will increase accessibility and availability of acute care services to the residents of Charleston, Berkeley and Dorchester counties,” an official from the S.C. Department of Health and Environmental Control wrote in a letter to Trident Wednesday.

The expansion in Dorchester County is the latest dispute in an ongoing legal battle between Trident Health System and the non-profit Roper St. Francis Healthcare that dates to 2008. The wrangling began with a battle over which of the systems should be allowed to build a new 50-bed hospital in neighboring Berkeley County. The state approved proposals from both Trident and Roper in June 2009.

Later that year, Trident appealed Roper’s approval. Officials from Trident, which filed its application with the state first, have said the area can support only one hospital.

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Roper then appealed Trident’s approval. Roper officials have said both systems should be allowed to build.

The hospital dispute is scheduled to go to trial in January.