NTSB Safety Recommendation Letter P-91-013 through P-91-016

Page 1Official PDFNational Transportation Safety Board Washington, D.C. 20594 Safety Recommendation Date: J u l y l o , 1992 In reply refer to: P-91-13 through -16 (Supersedes Safety Recommendation Letter Issued August 6, 1991) Mr. James A. Sutton President UGI Corporation Post Office Box 965 Valley Forge, Pennsylvania 19482 At 5:13 a.m. eastern daylight time on August 29, 1990, a natural gas explosion and fire destroyed two row houses at 421-423 North Fifth Street and damaged two adjacent houses and three parked cars in Allentown, Pennsylvania. One person was killed, and nine people, including two firefighters, were injured I Three hours before the accident, a police officer advised the Allentown public works dispatcher that water was leaking through pavement cracks in front of 421 North Fifth Street. The officer said that he believed that repairs could be deferred until the next day. Minutes after 5 a.m., a North Fifth Street resident notified the city of a gas odor in the area of 421 North Fifth Street and at 5:09 p.m., police and fire personnel arrived at the location. Four minutes later the explosion occurred. Firefighters and police evacuated residents from houses within the danger zone. To eliminate potential gas leaks from piping in adjacent residences, they closed the gas valves at inside meter sets. The fire department notified the gas operator, UGI Corporation (UGI), of the accident. When UGI employees arrived at 5:30 p.m., they began searching for leaking gas and found that several gas valves to residences had not been turned off. They then shut off gas to residences at the key-operated curb valves and then at meters where valves had not previously been closed. The UGI employees later located a broken cast-iron main ils the source of the leaking gas. Because they were not trained or equipped to close the curbside key- operated valves, the city emergency response personnel potentially endangered themselves when they entered buildings to close inside gas meter valves. ' N T S B B r i e f o f Accident File No. D C A 9 0 F P 0 0 1 (attached) 5530A#

Page 22 A1 though the UGI has trained emergency response agency personnel when requested, the training did not adequately cover the use of outside gas i service line valves. In its findings from previous accidents,' the Safety Board addressed the limited emergency response capabilities of gas operators and encouraged them to train and use local emergency response agency personnel to accomplish initial lifesaving actions until gas operator employees arrive on scene. To achieve effective results, gas operators must provide response personnel with thorough initial and recurrent training on identifying hazardous conditions and on the corrective actions to take. The National Transportation Safety Board's investigation disclosed that water leaking from a circumferential crack in a 6-inch cast-iron municipal water main beneath North Fifth Street's east side had eroded the soil foundation of a low pressure (9 inches water column pressure) 4-inch cast- iron UGI Corporation (UGI) gas main beneath the west side of North Fifth Street. The gas main subsequently cracked circumferentially and natural gas filled the void beneath the pavement. Natural gas then migrated through the soil and into the basement of 423 North Fifth Street, where it ignited, exploded, and burned. Subsequent metallurgical examinations revealed that both cast-iron mains were significantly weakened by graphitic corrosion. The water main was installed in the late 1800s and the gas main was installed in 1903. The Safety Board reviewed the operating and maintenance practices of both the city and UGI and previous natural gas accidents within the city. Based on these reviews, the Safety Board determined that: Prior to August 29, 1990, two breaks had occurred on the 4-inch cast-iron main in the 400 block of North Fifth Street on January 15, 1981, and January 24, 1988. Since 1970, UGI has averaged 1.2 reported incidents3 per year on its cast-iron mains. From 1925 to 1976, 10 persons were killed, 24 persons were injured, and 2 buildings were destroyed as the result of 2 gas explosions in the city of Allentown. Since 1976, 3 persons were killed, 23 persons were injured, 6 buildings were destroyed, and 5 buildings were damaged as a result of 2 gas explosions in the city of Allentown. I ' F o r more detailed information, read Pipeline Accident Report-- "National Fuel Cas Company, Natural Gas Explosion and Fire, Sharpsville, Pennsylvania, February 22, 1985" (NTSB/PAR-85/02). 3An incident means an event that involves a release o f gas from a pipeline and a death, personal injury requiring hospitalization, or estimated property damage of $ 5 0 . 0 0 0 or more (before J u l y 1 , 1984, the property damage amount uas S5.000).#

Page 3J o The Allentown i n f r a s t r u c t u r e contains many miles o f small diameter (8 inches and l e s s ) c a s t - i r o n gas and water mains i n s t a l l e d i n t h e l a t e 1800s and e a r l y 1900s t h a t have l i k e l y been weakened by corrosion. o Water from l e a k i n g storm, water, and sewage l i n e s has eroded and dissolved the s o i l supporting t h e water and gas mains and other s t r u c t u r e s c r e a t i n g sinkholes and o t h e r underground c a v i t i e s beneath t h e c i t y s t r e e t s . o Heavy t r a f f i c loads, cracked pavement, and s o i l movement have increased t h e stress on buried c a s t - i r o n mains. o The UGI, t h e c i t y , and other operators o f underground f a c i l i t i e s f i n d i n g s , t h a t b u t f i n d sinkholes and o t h e r voids when excavating have i n d i v i d u a l l y documented t h e i r a r e c i p r o c a l system f o r underground c e n t r a l l y documenting o r exchanging t h i s information does not e x i s t . o Although required by Federal Regulations (49 CFR 192.617), t h e UGI has n o t r o u t i n e l y submitted f a i l e d pipe segments, i n c l u d i n g c a s t - i r o n f a i l u r e s , f o r l a b o r a t o r y examination t o determine the cause f o r t h e f a i l u r e . o Although required by Federal r e g u l a t i o n s (49 CFR 192.613), the UGI has not implemented an adequate s u r v e i l l a n c e program t o i d e n t i f y p i p e l i n e segments, i n c l u d i n g c a s t - i r o n segments, i n i t s gas d i s t r i b u t i o n system t h a t r e q u i r e c o r r e c t i v e a c t i o n t o minimize the t h r e a t s t o p u b l i c safety. o The UGI has n o t coordinated s u f f i c i e n t l y w i t h l o c a l f i r e , p o l i c e , and other p u b l i c o f f i c i a l s t o f a m i l i a r i z e them w i t h UGI's emergency procedures f o r l o c a t i n g and using key-operated service l i n e s h u t o f f valves t o stop t h e gas f l o w t o b u i l d i n g s . I n i t s i n v e s t i g a t i o n , t h e Safety Board found t h a t t h e UGI's p r a c t i c e s regarding a s t - i r o n f a i l u r e s are not unique i n t h e n a t u r a l gas d i s t r i b u t i o n i n d u s t r y . From previous i n v e s t i g a t i o n s , the Safety Board has determined t h a t c u r r e n t i n d u s t r y p r a c t i c e s on c a s t - i r o n pipe replacement do n o t adequately i d e n t i f y and remove from service those gas mains t h a t threaten p u b l i c safety. The p r a c t i c e s were found inadequate because they do not g e n e r a l l y consider previous g r a p h i t i z a t i o n , corrosiveness o f t h e s o i l , bending s t r e n g t h o f small diameter pipe, l e a k h i s t o r y , and p o t e n t i a l p i p e damage i n areas being renovated o r subjected t o major adjacent excavation operations. The Safety Board found t h a t most gas operators, r a t h e r than submitting f a i l e d segments o f c a s t - i r o n p i p e f o r l a b o r a t o r y analysis t o determine t o what extent g r a p h i t i z a t i o n has weakened t h e pipe, normally do l i t t l e more than i n s t a l l a l e a k clamp around the crack and keep t h e c a s t - i r o n main i n operation. Some operators determine a pipe's c o n d i t i o n merely by having workers scrape#

Page 4the pipe area adjacent to the crack with a knife blade or rasp to see if they 1 can produce carbon shavings, a clear indication of severe graphitization. Some gas operators have implemented policies that called for replacing a cast-iron main within a city block after it has experienced three breaks and replacing cast-iron mains within a street intersection after two breaks. In its 1986 report4 on a natural gas explosion at Derby, Connecticut, that killed 6 people and injured 12 others, the Safety Board addressed the need for effective, programmed replacement of cast-iron gas mains. In that report, the Safety Board acknowledged that it had previously treated the cast-iron pipe failures on a case-by-case basis, making recommendations for corrective action only to the gas operator involved. The Safety Board also found that the number of miles of cast-iron pipe in gas distribution service had decreased over the years while the number of reportable accidents had remained relatively constant, indicating that the number of leaks per mile of cast-iron main was increasing. The Safety Board acknowledged that some large distribution operators had already begun identifying cast-iron systems prone to failure and established replacement programs. However, most operators had not, and no guidance existed at that time to assist or encourage them to develop cast-iron replacement practices. The Safety Board concluded that the industry should begin phasing out the cast-iron piping systems, many of which had been in service for more than 100 years. In the years since the Safety Board's report, the industry has taken only limited action to encourage the replacement of deteriorated and aging cast-.iron gas distribution systems. In 1986, the Gas Research Institute issued its report, "Cast Iron Maintenance Optimization System." This report contained a computerized evaluation model to assist operators in estimating the probability of breaks and leaks on individual segments of cast-iron gas mains, on evaluating repair versus replace options, and on identifying replacement priorities. Additionally, the American Gas Association (AGA) issued in 1990 a technical report, "Attention, Prioritizing, and Pipe Replacement/Renewal Decisions," that is a collection of papers to "provide a good overview of procedures in current use to maximize the benefits received from repair and replacement expenditures in existing gas systems." Those papers address: o Establishing annual maintenance and replacement budgets; o Establishing attention priorities for the sections of main that compromise a distribution system; and o Determining whether a troublesome section should be repaired or replaced. 4For more detailed information, reed Pipeline Accident Report-- "Northeast Utitities Service Company. Explosion and Fire, Derby, Connecticut, December 6 , 1985" (YTSB/PAR-86/02).#

Page 55 Also, the Gas Piping Technology Committee recently approved guidelines to assist gas operators in developing cast-iron replacement policies, and the AGA will distribute these to each gas operator that has cast-iron piping systems. The Safety Board is pleased that the gas industry now has an analytical tool and information on current repair/replacement practices, and soon should have guidelines to aid gas operators in establishing cast-iron system replacement policies, and believes that the UGI should implement gas system surveillance and cast-iron replacement programs to prevent similar accidents in the future. The Safety Board’s investigation determined that while underground facility operators performing an excavation will record the existence of underground voids, they notify other operators only when they see an underground structure within the void that belongs to another operator. This practice results in information not being consolidated and disseminated to all underground facility operators. Such information would aid all underground facility operators in identifying conditions that may adversely affect their facilities, in identifying city areas that may require enhanced surveillance, and in planning for new underground facilities. The Safety Board believes the city o f Allentown, because it operates several underground facilities and performs some liaison activities with all underground facility operators in the city, could best coordinate the development of a centralized process for collecting and documenting all discoveries of underground voids and make that information available to all operators of underground facilities. One method to coordinate the collection and dissemination of information would be to use the existing one-call excavation notification communication network that now has a communication network with underground facility operators. Therefore, the National Transportation Safety Board recommends that the UGI Corporation : Provide initial and recurrent training to local government emergency response personnel on how to control natural gas in emergency situations, including how to locate, identify, and operate outside key-operated shutoff valves. (Class 11, Priority Action) (P-91-13) Implement a comprehensive gas system surveillance program that: (1) identifies the type of data to be collected on gas system failures, gas leakage surveys, changes in corrosion protection levels, and abnormal operating and maintenance conditions; ( 2 ) establishes the type and frequency of analyses to be performed for identifying potentially unsafe conditions; and (3) specifies the corrective action to be taken. (Class 11, Priority Action) (P-91-14)#

Page 66 Implement a cast-iron pipe replacement program based on factors such as age, pipe diameter, operating pressure, soil corrosiveness, existing graphitic damage, leak history, burial depth, and external loading, to identify and replace in a planned, timely manner cast-iron piping systems that may threaten public safety. (Class 11, Priority Action) (P-91-15) Document the location of underground voids discovered during excavations and coordinate with the City of Allentown to develop systematic procedures for centrally reporting, documenting, and exchanging information on the location of underground voids. (Class 11, Priority Action) (P-91- 16) Also, the Safety Board issued Safety Recommendations P-91-12 to the Research and Special Programs Administration; P-91-17 to the National Association of Regulatory Utility Commissioners; and P-91-18 and -19 to the city of Allentown. The National Transportation Safety Board i s an independent Federal agency with the statutory responsibility "to promote transportation safety by conducting independent accident investigations and by formulating safety improvement recommendations" (Pub1 ic Law 93-633). The Safety Board is vitally interested in any action taken as a result of i t s safety recommendations. Therefore, it would appreciate a response from you regarding action taken or contemplated with respect to the recommendations in this letter. Please refer to Safety Recommendations P-91-13 through -16 in your reply. KOLSTAD, Chairman, COUGHLIN, Vice Chairman, and LAUBER and HART, Members, concurred in these recommendations. Member HAMMERSCHMIDT did not participate. COUGHLIN, Acting Chairman, and LAUBER, KOLSTAD, HART, and HAMMERSCHMIDT, Members, concurred in the revision of this Safety Recommendation Letter. 7 ?'A By: Susan M. Coughlin W-AR-JL y Acting Chairman#

Page 71 NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. 20594 Pipeline Accident Brief No. DCA90FP001 System Type: Distribution 6AUG 1991 Accident Type : Explosion and Fire Location: 421-423 North Fifth Street A1 lentown, Pennsylvania Date: August 29, 1990 Time: 0513 local daylight time Owner/Operator : UGI Corporation (UGI) Property Damage: $300,000 Injuries: 1 Fatal 9 Nonfatal Material Released: Natural Gas Pressure: 0.32 psig. (9 inches water column) Type Failure: Overstress Component Affected: Cast-Iron Main . . 1 . Description of the Accident A, natural gas explosion and fire destroyed two row houses at 421-423 North Fifth Street and damaged two adjacent houses and three parked cars in Allentown, Pennsylvania. Two of the injured were fire fighters. Three hours before the accident, a police officer advised the Allentown after-hours dispatcher that water was leaking through pavement cracks in - front of 421 North Fifth Street. The officer said that he believed that repairs could be deferred until the next day. Minutes after 5 a.m., a North Fifth Street resident notified the city of a gas odor in the area of 421 North Fifth Street and at 5:09 p.m., police and fire personnel arrived at Four minutes later, the’ explosion occurred. the location. Fire fighters and police evacuated residents from houses in the danger zone, and to eliminate potential gas leaks from piping in adjacent residences, they entered houses to close the gas valves at inside meter sets. When UGI employees arrived at 5:30 a.m., they began searching for leaking gas and discovered that several gas valves had not been Surned off. They then shut off gas to the residences at the key-operated curb valves and then at meters where valves had not previously been closed. The UGI employees then continued their search for the source of the gas leak and discovered a broken cast-iron main beneath the street. Investigation disclosed that water leaking from a cracked 6-inch cast- iron municipal water main had eroded the soil foundation beneath a 4-inch cast-iron UGI gas main. The gas main subsequently cracked due soil loads from above, releasing natural gas beneath the pavement. The gas migrated#

Page 8Notation 5530 2 DCA90FP001 through the soil was ignited, exploded, and burned. and into the basement of 423 North Fifth Street, where it Excavation after the accident revealed that both the 6-inch cast-iron municipal water main and the 4-inch cast-iron UGI gas pipeline had cracked circumferentially. Sections of each of the pipelines were sent to the Safety Board's laboratory for metallurgical analysis. Analysis revealed that both mains contained areas of significant graphitic corrosion that weakened them. The failure of the gas pipe was inevitable even had the water not eroded its soil foundation because one area of the gas pipe wall was fully graphitized. Numerous factors, individually and/or synergisticqjly, have contributed to the integrity reduction and failure of Allentown, Pennsylvania's cast-iron gas and water mains, most of which were installed in the late 1800s and early 1900s. These include: leaks from storm and sewer lines, water migrating or percolating through the soil, karst development, sinkholes, graphitization, shifting and cracking pavement, increased traffic load, and overburden stress. Probable Cause The National Transportation Safety Board determines that the probable cause of the natural gas explosion and subsequent fire, involving the overstress fracture of an undermined and weakened segment of cast-iron gas main, was the failure of the UGI Corporation to adequately monitor the condition of its gas system and to timely replace cast-iron segments weakened by graphitic corrosion. Recomendati ons As a result of its investigation, the National lransportation Safety Board made the following recommendations: --to the Research and Special Programs Administration: - Require each gas operator to implement a program, based on factors such as age, pipe diameter, operating pressure, soil corrosiveness, existing graphitic damage, leak history, burial depth, and external loading, to identify and replace in a planned, timely manner cast- iron piping systems that may threaten public safety. (C1 ass I I, Priority Action) (P-91-12) --to the UGI Corporation: Provide initial and recurrent training to local government emergency response personnel on how to control natural gas in emergency situations, including how to locate, identify, and operate outside key-operated shutoff valves. (Class 11, Priority Action) (P-91-13)#

Page 9Notation 5530 3 DCA90FPOOl Implement a comprehensive gas system surveillance program that: (1) identifies the type of data to be collected on gas system failures, gas leakage surveys, changes in corrosion protection levels, and abnormal operating and maintenance conditipns; (2) establishes the type and frequency of analyses to be performed for identifying potentially unsafe conditions; and (3) specifies the corrective action to be taken. (Class 11, Priority Action) (P-91-14) Implement a cast-iron pipe replacement program, based on factors such as age, pipe diameter, operating pressure, soil corrosiveness, existing graphitic damage, leak history, burial depth, and external loading, to identify and replace in a planned, timely manner cast- iron piping systems that may threaten public safety. (Class 11, Priority Action) (P-91-15) Document the location of underground voids discovered during excavations and coordinate with the City of Allentown to develop systematic procedures for centrally reoortina. documentina. and exchanaina information on the .. lokation-' o f underground voids. dass 11, Priority Action) (P-91-16) --to the National Association of Regulatory Utility Commissioners: Encourage its member states to require that .each gas operator implement a program, based on factors such as age, pipe diameter, operating pressure, soil corrosiveness , existing graphitic damage, 1 eak hi story, burial depth, and external loading, to identify and replace in a planned, timely manner cast-iron piping systems that may threaten public safety. (Class 11, Priority Action)(P-91-17) --to the City of Allentown: i Coordinate with the UGI Corporation to obtain initial and recurrent training for emergency response personnel on control1 ing natural gas in emergency situations, including how to locate, identify, and operate outside key-operated shutoff valves. (Class 11, Priority Action) (P-91-18) Coordinate with known underground facility operators in the immediate Allentown vicinity to develop systematic procedures for centrally reporting, documenting, and exchanging information on the location of underground voids discovered through excavations or other means. (Class 11, Priority Action)(P-91-19) . . . .#