Washington Gas Report to the D.C. PSC Regarding February 18, 2000 Pepco Manhole Fires and Explosions
Difficulty of Puncturing the Electric Cable
Pepco has suggested that a Washington Gas crew may have nicked an electric line on February 4, 2000 when it was inserting a test pinhole in a tree box to check for a possible gas leak. Pepco contends that the alleged nick contributed to the fault in the electric line that eventually led to the February 18 explosions and fires in the Pepco manholes. Washington Gas states that the test pinhole was more than one foot from the electric line. Additionally, according to forensic tests authorized by Washington Gas, it was not possible for a company employee to push a test pin rod through the terra cotta duct that surrounds and protects the electric cables. The insertion by hand of a test pin hole could not have produced sufficient weight or pressure to damage the outside terra cotta conduit. Forensic tests show that it would have taken in excess of 1,100 pounds of weight to do so. In addition to the terra cotta covering, the electric cables are protected by layers of polyethylene and neoprene insulation. If the terra cotta ductwork were already broken, the force required to break through the insulation with the test pin would have been in excess of 600 pounds. The amount of weight and pressure necessary to break through the terra cotta ductwork or the electric cable insulation was not present.
Point of Origin
The point where the fire may have started in the electric cable has not been determined. A report by the D.C. Fire Marshal's office said the point of origin could not be determined. Pepco's report to the D.C. Public Service Commission about the manhole fires and explosions includes a report by Cable Technology Laboratories, Inc. That report states: "It is not possible to establish if and which of the above named damages were present in the cable prior to the explosion or were caused during the fire and removal operation."
Missing Evidence
Pepco officials have acknowledged throwing away the terra cotta ductwork that protected the electric cable. The terra cotta duct was crucial to a thorough investigation and understanding of how the incident took place. At the March 22, 2000 hearing before the D.C. Public Service Commission, a D.C.Fire official acknowledged that the terra cotta duct would have been considered evidence in their investigation. The fact that this evidence is missing is of great concern to Washington Gas.
No Incident Scene Investigation
The D.C. Fire Marshal's report about the February 18, 2000 manhole explosions and fires notes that no fire scene examination was conducted because Pepco had removed components of the electric distribution system "prior to the examination by participating investigators." The report notes that the remains of the wires were at a Pepco facility. However, "the exact location of these wires in relation to their location within the conduit and point of origin could not be determined."
Tree Box Test Hole
On February 4, 2000, Pepco's own utility locating service was called to the scene to identify and locate the electric cable. The location of the electric cable under a tree box in front of 3111 M Street, N.W. was determined before the Washington Gas crew hand-pushed a test pinhole in the northwest corner of the tree box. Changes to the dimensions of the tree box and other unexplained adjustments to the space were made after the February 18, 2000 manhole explosions and fires. However, those changes do not impact the fact that the test hole placed by Washington Gas was over one foot away from Pepco's electric line. Scale drawings and actual photos of the tree box indicate the edge of the tree box where the test pinhole was placed is approximately 23 inches from the center of the electric line.
Recommendations
The Washington Gas report contains several recommendations to assist the D.C. Public Service Commission, the D.C. Fire Department and other public safety authorities, as well as other utilities, handle evidence at the scene of an incident that requires Fire Department investigation.
Those recommendations are:
- At the scene of an incident, the authority of the D.C. Fire Department must be recognized as the official agency in control. The Fire Department is an objective third party with experience in dealing with fires, explosions, and preservation of evidence, and is best suited to take the lead in any subsequent investigations. This procedure is followed in Maryland and Virginia and ensures protection of an incident scene and related evidence, as well as contributing to an objective set of findings and conclusions. Parties on the scene of an incident must permit the Fire Department to exercise its authority.
- Utility locating companies must formalize and improve documentation and procedures for locating facilities.
Summary
As Washington Gas has said continuously, natural gas was not involved in the February 18, 2000 manhole explosions and fires in Georgetown. That fact was finally acknowledged by Pepco in its March 20, 2000 report. In addition, the Pepco allegation that a Washington Gas employee may have nicked its cable defies the existing evidence and testing that are documented in Washington Gas's report. Washington Gas appreciates the opportunity to assist the public and the D.C. Public Service Commission in understanding what did and did not happen with regard to the Pepco manhole explosions and fires on February 18, 2000.
Edited by Stephen Heiser