Main Line Health plans to build a new patient pavilion at Riddle Hospital, near Media, the nonprofit said in a preliminary bond offering document that aims to raise $131 million toward the $327 million cost of the Riddle modernization. The bonds will also help pay for routine capital projects at other Main Line Health locations.

The Riddle plan awaits final approval from Middletown Township, Delaware County. The bond filing was published Friday.

Main Line Health, which acquired Riddle in 2007, said the new building will include a new main entrance and reduce Riddle’s overall inpatient capacity to 174 beds, in private rooms, from the current staffed capacity of 193 beds. The reduction “is consistent with the projected inpatient demand through 2028,” the document said.

In addition to replacing shared rooms in the existing hospital, the new building will house imaging facilities, laboratories, the hospital pharmacy and kitchen, plus 10 new operating rooms, among other facilities. Renovations in the existing hospital will include the creation of a 13-bed intensive care unit and other departments. The plan also calls for the demolition of two older sections of the hospital, the East Wing and Annex 1, to make room for new parking.

Main Line has already undertaken major capital projects at its other acute-care hospitals in the last decade or so. Those are Bryn Mawr Hospital, Paoli Hospital, and Lankenau Medical Center, where a $465 million expansion completed in 2013 was followed by the construction of a new, $52.8 million emergency department. Main Line also spent $250 million on a modernization at Bryn Mawr, completed about a year ago. Major projects at Paoli were undertaken earlier.

Moody’s Investors Service gave the proposed bonds a strong “Aa3” rating, saying it expected Main Line Health to “benefit from its position as a leading provider in the Philadelphia suburbs," where it has "favorable service area demographics and low exposure to Medicaid.”

Despite the strong tailwind from its presence in relatively well-off areas, Main Line also faces challenges, Moody’s said: “Competition will remain high with close proximity to large tertiary providers in surrounding markets, some of which are making inroads into MLHS’ service area.”

In the year ended June 30, Main Line Health had $33 million of operating income on $1.8 billion in total revenue.