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Safety Recommendation Details

Safety Recommendation P-19-001
Synopsis: On August 10, 2016, at 11:51 p.m., eastern daylight time, a 14-unit apartment building, located at 8701 Arliss Street, in the unincorporated community of Silver Spring, in Montgomery County, Maryland, partially collapsed due to a natural gas-fueled explosion and fire. The explosion and fire also heavily damaged an adjacent apartment building, 8703 Arliss Street, which shared a common wall with building 8701. As a result of this accident, 7 residents died, 65 residents were transported to the hospital, and 3 firefighters were treated and released from the hospital. The damage from the accident exceeded $1 million. The following are safety issues in this accident: • the location and inspection of service regulators within a structure • the inspection of the gas meter assembly • the notification of the natural gas odor to Washington Gas Light Company • the detection of natural gas through odorants and methane
Recommendation: TO THE PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION: Require that all new service regulators be installed outside occupied structures.
Original recommendation transmittal letter: PDF
Overall Status: Open - Initial Response Received
Mode: Pipeline
Location: Silver Spring, MD, United States
Is Reiterated: No
Is Hazmat: No
Accident #: DCA16FP003
Accident Reports: Building Explosion and Fire
Report #: PAR-19-01
Accident Date: 8/10/2016
Issue Date: 6/10/2019
Date Closed:
Addressee(s) and Addressee Status: PHMSA (Open - Initial Response Received)

Safety Recommendation History
Date: 9/5/2019
Response: -From Howard R. Elliott, Administrator: The mission of PHMSA is to protect people and the environment by advancing the safe transportation of energy and other hazardous materials that are essential to our daily lives. PHMSA shares the NTSB' s commitment to preventing pipeline accidents. PHMSA has a long history of cooperating and collaborating with the NTSB, and we take our responsibility to address all of NTSB's recommendations seriously. While PHMSA' s regulations allow service regulators to be located inside or outside structures, the requirements for indoor regulators are more stringent than for those located outdoors. Specifically, 49 CFR § 192.355(b) requires service regulator vents to terminate outdoors; § 192.357(d) requires regulators that might release gas to be vented to the outside atmosphere; and § 192.353 requires each service regulator to be located in a readily accessible location, and that if service regulators are installed in a building they must be located as near as practical to the service line entrance to the building. In general, locating service meter and regulator sets inside structures is more costly and presents access challenges for operators. Today, most sets are placed outside unless no safe and suitable space exists outside. PHMSA' s regulations also include requirements that operators conduct leakage surveys of their systems, including service regulators located inside or outside a building. In scheduling these, they may consider the nature of their operations and the local conditions, but at a minimum they must conduct surveys: (1) in business districts at intervals not exceeding 15 months, but at least once each calendar year; and (2) outside business districts as frequently as necessary, but at least once every five calendar years at intervals not exceeding 63 months (See § 192.723). In addition,§ 192.481 requires operators to inspect meters and regulators for atmospheric corrosion at least once every 3 years, at intervals not to exceed 39 months. Requiring service regulators and meter sets to be located outside could have unintended consequences. When located outside, regulator and meter sets are at risk of damage from vehicular traffic. From 2005 through 2018, gas distribution pipeline system releases resulted in a fatality or injury requiring hospitalization 3 72 times. Of these releases, 18% were caused by vehicular damage to meter and regulator sets located outside. Operators should be allowed to evaluate each service installation to determine the appropriate location of the service regulators. Further, in our analysis to respond to the above Recommendations, PHMSA assumed that operators would incur no additional costs to place service regulators outside for new construction (P-19-001 ). However, PHMSA estimates that implementing Recommendation P-19-002 could involve inside regulators serving approximately 13.9 million existing occupied structures, at an estimated cost of $520 million during the first year. This makes it unlikely that the estimated cost of relocating service regulators outdoors would pass the statutory cost/benefit requirements for rulemaking. To arrive at this conclusion, PHMSA used 2018 data collected through PHMSA's Gas Distribution Annual Reports. PHMSA's preliminary analysis of this data indicates that there is a total of 69,330,683 service lines operated by 1,462 pipeline operators nationally. Based on estimates provided by gas utility companies and the National Association of Pipeline Safety Representatives, as much as 20 percent of occupied structures are likely to be served by regulators located inside. PHMSA also assumes a 0.5 percent replacement rate each year, leading to recurring annual costs of a similar yet decreasing magnitude. As NTSB is aware, completing rulemakings takes time, as it is an iterative process that is designed to encourage maximum participation by all stakeholders, thus ensuring comprehensive rules that protect the public and stand up to cost/benefit scrutiny. For the reasons stated above, PHMSA believes the intent of both NTSB Recommendations can be achieved quickly by implementing the following alternatives: • Add questions and guidance to PHMSA's distribution inspection forms that are used by PHMSA and state pipeline safety inspectors to clearly guide them to review operators' compliance with our regulations relating to service regulators, and to have them review operator's Operation and Maintenance procedures relative to the placement of service regulators; • Modify the State Program Evaluation Form to include a question verifying that states are checking operator compliance with our regulations for inside regulators; • Review current requirements for inside meter/regulators with operators at all state pipeline safety seminars beginning in 2020; • Issue an Advisory Bulletin alerting operators of the requirements for inside meter/regulators, including leakage surveys, noting that if access is an issue to properly check and maintain inside regulators, operators must do what is necessary to have the customer provide access to check the regulator and conduct the leak or atmospheric corrosion survey; • Encourage states to provide a rate rider to move regulators outside where possible; and • Support research and development to improve service regulator design to facilitate placement in areas where very limited outside space exists. PHMSA proposes to track the efficacy of these alternative actions by: • Working with the National Association of Pipeline Safety Representatives to determine a baseline for the number of inside regulators. PHMSA would then annually track this data to determine the rate of reduction in inside regulators; • Reviewing incident data to identify potential trends for Material/Weld/Equipment failures involving inside regulators; and • Reviewing Federal and state inspection and enforcement relative to compliance with the regulations. PHMSA proposes to submit our findings to NTSB one year after the implementation of the above plan. PHMSA is committed to continuously help improve the safety of our nation's pipeline system. Towards that end, we take our responsibility to address all NTSB recommendations seriously. PHMSA is requesting that NTSB accept our alternative actions to address the intent of Recommendations P-19-001 and P-19-002. My staff and I would be pleased to meet with you to further discuss this proposal. We look forward to a favorable response.

From: NTSB
Date: 6/10/2019
Response: On April 24, 2019, the National Transportation Safety Board (NTSB) adopted its report, Building Explosion and Fire, Silver Spring, Maryland, August 10, 2016, NTSB/PAR-19/01. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at As a result of this investigation, the NTSB identified the following safety issues: • The location and inspection of service regulators within a structure. • The inspection of the gas meter assembly. • The notification of the natural gas odor to Washington Gas Light Company. • The detection of natural gas through odorants and methane. Accordingly, the NTSB makes the following safety recommendations to the Pipeline and Hazardous Materials Safety Administration (PHMSA). Additional information regarding these recommendations can be found in the noted sections of the report. • Require that all new service regulators be installed outside occupied structures. (P-19-001) (See section 2.3.10.) • Require existing interior service regulators be relocated outside occupied structures whenever the gas service line, meter, or regulator is replaced. In addition, multifamily structures should be prioritized over single-family dwellings. (P-19-002) (See section 2.3.10.) The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days, detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendations by number. We encourage you to submit your response to If your reply exceeds 20 MB, including attachments, please e-mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response.