Work will begin soon on restoring portions of historic Kawaiaha‘o Church’s 169-year-old wall that were heavily damaged April 2 when a city bus crashed into it.

On Monday, workers cleared the stone and concrete rubble that had sat for 4 1⁄2 months at the busy downtown intersection of Punchbowl and South King streets.

The rebuilding, by Construction Associates, will take roughly five to six weeks at a cost of between $69,000 and $100,000, said William Haole, chairman of the board of trustees of Kawaiaha‘o Church.

The objective is to make it "historically pono" — "trying to preserve as much as possible at all costs," he said. "My personal objective is to get it done by the holidays."

The original was built as a6-foot-high wall in 1843, much of it with pieces of the same hand-hewn blocks of Oahu coral reef stone as the church, known then as the Stone Church, constructed in 1840.

But some pieces are missing at the hands of "souvenir gatherers," Haole said. "We have full knowledge that some people have helped themselves to the rocks."

All the wall pieces from the original construction will be saved, said Glenn Mason, a local architect who specializes in restoration of historic structures.

Mason said his firm began work quickly. He said he was contacted a couple of weeks after the accident, and plans were drawn and submitted to the state Historic Preservation Division for approval, but the process took time.

The top of one of the pillars flanking the front walkway gate was cracked during the accident but had been removed and kept in a safe place.

The part will be fixed and "gently placed back on top," Mason said. "We will literally try to glue it back together again."

Should that fail, the pillar will be recast, which would raise the cost to $100,000.

Mason said very little of the straight sections of the original wall, which contain a lot of coral block, was damaged. Most of the damage was in the curved section, which contained little coral.

The original stone will be reset, but the curved section — rebuilt in the 1940s or 1950s with basalt and concrete — will be recast and plastered over, trying to match the coral color of the existing plaster of coral sand and aggregate.

The 44-year-old city bus driver, who was seriously injured and was suspected of having a medical condition, remains on medical leave, said Oahu Transit Services President Roger Morton. He said he could not discuss details of the driver’s health.