NTSB Safety Recommendation P-01-001

NTSB safety recommendation P-01-001.

TO RSPA: Require gas utility operators to maintain a specified minimum separation distance, sufficient to protect against both thermal and mechanical damage, between plastic gas service lines and underground electrical facilities whenever they install a new gas service line or perform maintenance on existing lines.

Priority: CLASS II

Overall Status: Closed - Acceptable Alternate Action

Issued Date: 2001-06-22

Adopted Date: 2001-06-12

Overall Date Closed: 2004-04-15

Synopsis: About 12:55 a.m. on 7/7/98, a natural gas explosion and fire destroyed a newly constructed residence in the south riding community in Loudoun County, Virginia. A family consisting of a husband and wife and their two children were spending their first night in their new home at the time of the explosion. As a result of the accident, the wife was killed, the husband was seriously injured, and the two children received minor injuries. Five other homes and two vehicles were damaged. The national transportation safety board determined that the probable cause of this accident was the corrosion and subsequent overheating and arcing at a splice in one of the conductors of the triplex electrical service line, which, because of inadequate separation between the electrical conductors and the gas service line, led to the failure of the gas service line and the subsequent uncontrolled release of natural gas that accumulated in the basement and was subsequently ignited. Precipitating the electrical service line failure was damage done to the electrical service line during installation of the gas service line and/or during subsequent excavation of the electrical line.

Probable Cause: The National Transportation Safety Board determined that the probable cause of this accident was the corrosion and subsequent overheating and arcing at a splice in one of the conductors of the triplex electrical service line, which, because of inadequate separation between the electrical conductors and the gas service line, led to the failure of the gas service line and the subsequent uncontrolled release of natural gas that accumulated in the basement and was subsequently ignited. Precipitating the electrical service line failure was damage done to the electrical service line during installation of the gas service line and/or during subsequent excavation of the electrical line.

Ntsbnumber: DCA98MP003

Report Number: PAR-01-01

Addressee Name: RSPA

Addressee Status: Closed - Acceptable Alternate Action

Addressee Date Closed: 2004-04-15

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 2002-06-14

Communication Type: Official Correspondence

Communication Contents: These initiatives are all responsive to the objective of the Board's recommendation. Accordingly, Safety Recommendation P-01-1 is classified "Open--Acceptable Response," pending the completion of RSPA's action to address this issue.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 2004-04-15

Communication Type: Official Correspondence

Communication Contents: The Safety Board understands that RSPA investigated underground separation between gas and electrical service lines in conjunction with its damage prevention best practices initiative and worked with the Common Ground Alliance (CGA) to investigate damage prevention solutions. These solutions included development of recommendations for minimum separation distance to protect plastic gas service lines from damage resulting from proximity to other underground facilities, such as electrical lines and other pipelines. Through a cooperative agreement, RSPA and the CGA evaluated the separation requirements in the National Electric Safety Code (NESC): this evaluation determined that a 12-inch separation is usually adequate. On September 26, 2003, the CGA Board of Directors approved a new best practice, stated below, to address the minimum separation of underground utilities, which addresses the interactions of all types of utility lines that could exist in a common trench: When installing new direct buried supply facilities in a common trench, a minimum of 12 inch radial separation should be maintained between supply facilities such as steam lines, plastic gas lines, other fuel lines, and direct buried electrical supply lines. If 12 inches separation cannot be feasibly attained at the time of installation, then mitigating measures should be taken to protect lines against damage that might result from proximity to other structures. Examples may include the use of insulators, casing, shields or spacers. If there is a conflict among any of the applicable regulations or standards regarding minimum separation, the most stringent should be applied. In addition, RSPA implemented a regional partnership program and participated in the group's first meeting in December 2003 to strengthen damage prevention initiatives among national, regional, State, and local damage prevention groups and to promote the use of damage prevention best practices. The program includes more than 19 partners, including regional organizations in Colorado, Georgia, Minnesota, Missouri, Ohio, Tennessee, and Wisconsin. To effectively manage this initiative and improve implementation of damage prevention best practices, RSPA's Office of Pipeline Safety (OPS) has hired a Community Assistance and Technical Support (CATS) inspector, for each of the five pipeline safety regional offices, to work with the CGA and one-call centers. According to RSPA, the CATS inspectors work with the CGA to promote regional partnerships through industry presentations, conventions, e-mail lists, and one-call centers. Because the CGA's best practice, coupled with the OPS CATS inspection program, provide an acceptable alternative solution to the recommended action, Safety Recommendation P-01-1 is classified "Closed--Acceptable Alternate Action."

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 2002-04-23

Communication Type: Official Correspondence

Communication Contents: Letter Mail Controlled 05/07/2002 10:27:21 AM MC# 2020456 RSPA determined that underground separation between gas and electrical service lines should be addressed as part of its damage prevention "best practices" initiative. RSPA has entered into a cooperative agreement with the Common Ground Alliance (CGA) to investigate damage prevention solutions, including development of recommendations for minimum separation distance to protect plastic gas service lines from damage resulting from proximity to other underground facilities (including electrical lines). A CGA team is now investigating the issue, including consideration of the electrical conductor radial separation requirements included in the new edition of the National Electric Safety Code (NESC), which is the safety standard used by electric power companies. An NEC study demonstrated that 12-inch separation is usually adequate. RSPA will consider the results of the CGA work, review the utility separations rules recently adopted in Virginia, consult with state and local officials, and seek public comments on the underground separation issue. Then, RSPA will determine if changes are necessary in the pipeline safety regulations for vertical and horizontal separations on mains and the extension of separation requirements to gas service lines.

Addressee Acronym: RSPA

Addressee Organization Type: G-Federal Government

Communication Date: 2004-02-17

Communication Type: Official Correspondence

Communication Contents: Letter Mail Controlled 2/24/2004 12:21:51 PM MC# 2040086 RSPA determined that underground separation between gas and electric service lines should be addressed as part of its damage prevention "best practices" initiative. RSPA entered into a cooperative agreement with the Common Ground Alliance (CGA) to investigate damage prevention solutions, including development of recommendations for minimum separation distance to protect plastic gas service lines from damage resulting from proximity to other underground facilities (including electrical lines). The CGA Best Practices Committee investigated the issue, including consideration of the electrical conductor radial separation requirements included in the new edition of the National Electric Safety Code (NESC), which is the safety standard used by electric power companies. A NBSC study demonstrated that 12-inch separation is usually adequate. On September 26, 2003, the CGA Board of Directors approved a new Best Practice to address the issue of minimum separation of underground utilities: When installing new direct buried supply facilities in a common trench, a minimum of 12 inch radial separation should be maintained between supply facilities such as steam lines, plastic gas lines, other fuel lines, and direct buried electrical supply lines. If 12 inches separation cannot be feasibly attained at the time of installation, then mitigating measures should be taken to protect lines against damage that might result from proximity to other structures. Examples may include the use of insulators, casing, shields or spacers. If there is a conflict among any of the applicable regulations or standards regarding minimum separation, the most stringent should be applied. This is included in CGA's Best Practices publication, which includes a broad range of Best Practices for underground facility damage prevention. CGA has also implemented a "regional partnership program" to strengthen damage prevention initiatives among national, regional, state, and local damage prevention groups and to promote the use of damage prevention Best Practices. The partnership program has grown to more than 19 partners, including regional organizations in Colorado, Georgia, Minnesota, Missouri, Ohio, Tennessee, and Wisconsin. RSPA's Office of Pipeline Safety (RSPAIOPS) has hired Community Assistance and Technical Support (CATS) inspectors in each of the five pipeline safety regional offices to work with CGA and one-call centers to improve implementation of damage prevention best practices. RSPA/OPS' CATS inspectors work with CGA to promote regional partnerships through industry presentations, conventions, e-mail lists, and one-call centers. RSPA/OPS participated in the first CGA regional partnership meeting in December 2003. RSPA believes that the CGA promulgation of this new Best Practice on underground separations addresses the interactions of all types of utility lines that could exist in a common trench. We believe this action is adequate to address the NTSB recommendation. RSPA requests that Safety Recommendation P-01-1 be reclassified as "CLOSED - Acceptable Response" based on the alternative action described above.