Unexpected conditions will delay the completion of a utility tunnel intended to service the Capitol Visitor Center by more than five months and could increase costs for the construction project, the Architect of the Capitol told Senate appropriators Tuesday.

In a hearing before the Appropriations subcommittee on the legislative branch, Architect of the Capitol Alan Hantman acknowledged that additional work related to D.C. Water and Sewer Authority-owned pipelines has significantly delayed progress on a utility tunnel being constructed beneath East Capitol Street.

The tunnel had been expected to be operational in October, but that date has been pushed back to March 2006.

Hantman testified that the setback should not impact the CVC’s expected September 2006 completion; however, he said a temporary dehumidifying system will be required in the facility to finish other aspects of the project, including plaster work.

“It looks like you’ll be able to catch up on your schedule but it’s going to cost some extra dollars,” noted Sen. Wayne Allard (R-Colo.), who chairs the subcommittee.

AOC officials could not immediately provide estimates for additional costs related to the utility tunnel, which will provide chilled water and steam to the 588,000-square-foot subterranean facility located beneath the Capitol’s East Front.

Although the Architect has previously estimated the CVC’s price tag will reach $517 million by the time it is completed, the Government Accountability Office puts those costs as high as $559 million, including funds to cover “risks and uncertainties” that may occur.

Specifically, GAO officials stated that the Architect’s office may need an additional $5 million to $15 million on top of the $36.9 million it has already requested for fiscal 2006.

During the hearing, the second in a series of monthly meetings Allard has called to review progress on the project, GAO officials likewise questioned the Sept. 15, 2006, target completion date set by the Architect.

“We continue to believe at this point that the project is more likely to be substantially completed in the December 2006 to March 2007 timeframe as opposed to a September 2006 schedule that currently exists,” said GAO’s director of physical infrastructure issues, Bernard Ungar.

According to GAO, Manhattan Construction Co., the firm contracted for the second phase of the visitor center — including mechanical, electrical and plumbing systems; completion of the East Front Plaza; and buildout of the interior spaces — met only three of 11 “milestones” scheduled for completion before the Monday hearing.

While numerous factors, such as “unforeseen site conditions and a design problem,” contributed to the delays on activities including stone work, masonry and the utility tunnel, the AOC does not expect the missed deadlines to impact the project’s current timeline, GAO officials noted.

But, Ungar added: “If we were responsible for the project we would not necessarily be able to sleep well at night.”

While Manhattan Construction has reordered its schedule to address the problems and recover time, Ungar expressed concern that the “stacking of activities toward the end” could prevent the project from meeting its finish date.

In addition, Congressional officials also addressed questions over worksite safety first raised at a May hearing on the visitor center.

GAO officials reported that in recent months, accident rates at the construction site have significantly improved. “Generally, things are better,” said Terrell Dorn, GAO’s assistant director of physical infrastructure issues.

In addition, Hantman noted that the a surprise inspection of the site in late May by the Occupational Safety and Health Administration did not produce any citations.

An earlier GAO report discussed at the May hearing had found accident and incident rates during the project’s initial phase occurring at a much higher rate than the national average for nonresidential construction sites.

But officials at Centex Construction, the firm contracted to complete the first phase of the project, have since defended its record in a June 3 letter to House and Senate appropriators, asserting the analysis inaccurately compared figures from the CVC site to national averages that did not correlate to the type of work being performed.

GAO officials asserted during the Monday hearing, however, that Centex, along with OSHA officials, had agreed to measure performance at the CVC site against those national figures used in the analysis.

“We believe the information reported in our last testimony was correct,” Ungar said.

Sen. Dick Durbin (D-Ill.) has requested that GAO formally reply to the Centex letter.