After exhausting their appeals with the District of Columbia government, Congressional law enforcement officials have enlisted the help of Senate leaders to block the construction of a private building near the Capitol grounds, asserting the structure constitutes a potential security threat.

At the request of the Capitol Police Board, the Senate approved a measure Tuesday that would prohibit the construction of a 12-story office building at 51 Louisiana Ave. NW, located near the Capitol’s Senate wing.

The District’s Board of Zoning Adjustments had approved the same project earlier this year — granting the project a variance requested by the owners so they could exceed maximum height limitations — despite objections from Congressional officials.

But under the Senate proposal, approved on voice vote as an amendment to the Interior appropriations bill, the project would now need the approval of both Congressional leadership and the police board to proceed as planned.

“This amendment does not preclude development of the property, but it ensures that existing height regulations are honored and the security of the Capitol and all the people who work here [are] protected,” Sen. Conrad Burns (R-Mont.) said Monday when he introduced the measure for its sponsors, Majority Leader Bill Frist (R-Tenn.) and Minority Leader Harry (D-Nev.).

According to documents filed with the D.C. Office of Zoning, which includes the BZA and the Zoning Commission, The JBG Companies plans to raze an existing five-story parking garage to construct the new facility. The site is also home to the historic Acacia Building, which would be connected to the new facility.

The police board’s concerns with the project center on the structure’s proposed 130-foot height, which would exceed zoning regulations for that section of the city by 20 feet.

Senate Sergeant-at-Arms Bill Pickle asserted in documents filed with the Zoning Office that allowing such a building would create “increased vulnerability” to Congressional security.

Architect of the Capitol Alan Hantman similarly objected to the building’s height in a Jan. 3 letter to BZA Chairman Geoff Griffis.

“The lines of sight that would be created from the roof and penthouse of the proposed structure would present a serious security risk to the Senate wing of the Capitol,” Hantman wrote.

Although Congressional law enforcement officials declined to detail the potential threat, BZA officials asserted that the source of the concerns centers on the potential for sharpshooters or other gunmen to use the new building as a base for attacking the Capitol.

“It can be inferred from the letter that the Sergeant at Arms and the Architect of the Capitol are concerned with the possibility that a sniper could perch himself on the roof of the proposed new building and fire into the Capitol Building,” BZA officials wrote in a Jan. 18 order approving the project and providing the variance.

But relying on a study conducted by the Connecticut-based security consulting firm Ducibella Venter and Santore for JBG, BZA rejected the police board’s concerns.

“While the consulting firm acknowledged that a sniper threat is ‘legitimately credible,’ it pointed out that such a threat is similarly credible, indeed perhaps more credible, from other nearby buildings,” the BZA order states.

BZA also cited the report’s finding that existing buildings in the area, including the Hyatt Regency Hotel, would be more favorable to potential snipers.

“The hotel is a far more attractive location to initiate a sniper assault, as the anonymity of its occupants and their activities are indigenous to the hotel’s operation,” the consulting firm’s senior principal, Robert Ducibella, stated in a Jan. 17 letter to JBG officials that BZA cited in its decision.

In issuing its decision, BZA officials asserted: “[T]he remote risk to one building, even a building as singularly important as the Capitol, cannot be allowed to dictate the zoning and design mandates for an entire neighborhood.”

According to a March 4 letter addressed to JBG Founder and Managing Partner Benjamin Jacobs, however, the police board voiced disagreement with the Ducibella Venter and Santore report.

“[A]fter further consideration, we cannot accept your contention that there are no security issues,” Pickle wrote. “Indeed, our security and law enforcement professionals have advised that, from a security perspective, the variance to increase the height of the building would increase exposure and vulnerability to the Capitol complex.”

Subsequently, following D.C. Zoning Office Director Jerrily Kress’ formal approval of the BZA order in April 2005, the police board filed an appeal with the Zoning Commission, which denied that request June 20.

According to correspondence filed with the Zoning Office, JBG officials did meet with police board officials regarding their concerns prior to the BZA ruling.

In a Jan. 21 letter addressed to the Senate Sergeant-at-Arms, Jacobs offered to implement additional security measures.

“The BZA’s action does not require the implementation of the security arrangements that we discussed,” Jacobs wrote. “However, I am very respectful of the concerns you expressed and the importance of your mission; accordingly, I remain willing to implement the building security precautions I described to you during our meeting and as recommended in the Ducibella January 17, 2005, report.”

In an interview Tuesday, Pickle said the Senate action is intended to give more time to review the security aspects of the building.

“We just want a thoughtful process to take place … to make sure it does not pose a security problem,” Pickle said, later adding: “This amendment is not meant to do anything but make sure that we all take a deep breath, look at the proposed building and then decide whether it’s a go or a no-go.”

The Senate amendment would provide for an evaluation of the proposal that Pickle said would likely be contracted to an outside agency.

An attorney representing JBG said the firm would continue to respond to the police board’s concerns, but questioned the need for legislation.

“Our plans are to be responsive to the security issues that are … addressed by the legislation,” said Richard Nettler, an attorney with Robins, Kaplan, Miller and Ciresi. “We don’t think the legislation is a necessary or fruitful way of trying to resolve it.”