NTSB Safety Recommendation Letter P-91-018 through P-91-019

Page 1Official PDFNational Transportation Safety Board Washington, D.C. 20594 Safety Recommendation Date: J u l y i o , 1992 In reply refer to: P-91-18 and -19 (Supersedes Safety Recommendation Letter Issued August 6, 1991) Honorable Joseph S. Daddona Mayor City of Allentown 435 Hamilton Street A1 lentown, Pennsylvania 18101 A t 5:13 a.m. eastern daylight time on August 29, 1990, a natural gas explosion and f i r e destroyed two row houses a t 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 f i r e f i g h t e r s , were injured.' 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 t h a t he believed that repairs could be deferred until the next day. Minutes a f t e r 5 a.m., a North Fifth Street resident notified the c i t y of a gas odor in the area of 421 North Fifth Street and a t 5:09 p.m., police and f i r e personnel arrived a t the location. Four minutes l a t e r 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 a t inside meter s e t s . The f i r e department notified the gas operator, UGI Corporation (UGI), of the gas leak. When UGI employees arrived a t 5:30 p.m., they began searching for leaking gas and found t h a t several gas valves had n o t been turned o f f . They then shut off gas t o residences a t the key-operated curb valves and then a t meters where valves had n o t previously been closed. The UGI employees l a t e r located a broken cast-iron main as the source of the leaking gas. Because they were not trained or equipped t o close the curbside key- operated valves, the c i t y emergency response personnel potentially endangered themselves when they entered buildings t o close inside gas meter valves. A1 though the UGI has trained emergency response agency personnel when requested, the training did n o t adequately cover the use of outside gas service l i n e valves. In i t s findings from previous accidents,2 the Safety 'NTSB Brief of Accident File N o . DCAPOFPOOl (attached). ' F o r more detailed information, read Pipeline Accident Report-- "National Fuel Gas Company, Natural cas Explosion and Fire. Sharpsville, Pennsylvania, February 2 2 , 1985" (NTSB/PAR-85/02). 5530k#

Page 22 Board addressed the 1 imited 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 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. lhe 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 is the city of Allentown. 'The Allentown infrastructure contains many miles of small diameter (8 inches and less) cast-iron gas and water mains installed in the late 1800s and early 1900s that have likely been weakened by corrosion. p i p e l i n e p r o p e r t y a m o u n t 3 A n i n c i d e n t means a n e v e n t t h a t i n v o l v e s a r e l e a s e o f g a s f r o m a a n d a d e a t h , damage o f p e r s o n a l $50.000 o r i n j u r y r e q u i r i n g h o s p i t a l i z a t i o n , o r m o r e ( b e f o r e J u l y 1 , 1 9 8 4 , t h e e s t i m a t e d p r o p e r t y d a m a g e w a s 5 5 , 0 0 0 ) \#

Page 33 o Water from leaking storm, water, and sewage lines has eroded and dissolved the soil supporting the water and gas mains and other structures creating sinkholes and other underground cavities beneath the city streets. o Heavy traffic loads, cracked pavement, and soil movement have increased the stress on buried cast-iron mains. o The UGI, the city, and other operators of underground facilities that find sinkholes and other underground voids when excavating have individually documented their findings, but a reciprocal system for centrally documenting or exchanging this information does not exist. o The UGI has not coordinated sufficiently with local fire, police, and other public officials to familiarize them with UGI's emergency procedures for locating and using key-operated service line shutoff valves to stop the gas flow to buildings. 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 of 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 excakation not,ification communication network that now has a communication network with underground facility operators. Therefore, the National Transportation Safety Board recommends that the city of A1 1 entown : Coordinate with the UGI Corporation to obtain initial and recurrent training for emergency response personnel on controlling natural gas in emergency situations, including how to locate, identify, and operate outside key-operated shutoff valves. (Class 11, Priority Action) (P-91- 18)#

Page 44 Coordinate w i t h known underground f a c i l i t y operators i n t h e immediate Allentown v i c i n i t y t o develop systematic procedures f o r c e n t r a l l y reporting, documenting, and exchanging information on t h e l o c a t i o n o f underground voids discovered through excavations o r o t h e r means. (Class 11, P r i o r i t y Action) (P-91-19) Also, t h e Safety Board issued Safety Recommendations P-91-12 t o t h e Research and Special Programs Administration; P-91-13 through -16 t o U G I Corporation; and P-91-17 t o t h e National Association o f Regulatory U t i l i t y Commissioners. The National Transportation Safety Board i s an independent Federal agency w i t h t h e s t a t u t o r y r e s p o n s i b i l i t y " t o promote t r a n s p o r t a t i o n s a f e t y by conducting independent accident i n v e s t i g a t i o n s and by formulating s a f e t y improvement recommendations" (Pub1 i c Law 93-633). The Safety Board i s v i t a l l y i n t e r e s t e d i n any a c t i o n taken as a r e s u l t o f i t s s a f e t y recommendations. Therefore, it would appreciate a response from you regarding a c t i o n taken o r contemplated w i t h respect t o t h e recommendations i n t h i s l e t t e r . Please r e f e r t o Safety Recommendations P-91-18 and -19 i n your r e p l y . KOLSTAD, Chairman, COUGHLIN, Vice Chairman, and LAUBER and HART, Members, concurred i n these recommendations. Member HAMMERSCHMIDT d i d n o t p a r t i c i p a t e . LOUGHLIN, Acting Chairman, and LAUBER, KOLSTAD, HART, and HAMMERSCHMIDT, Members, concurred i n t h e r e v i s i o n o f t h i s Safety Recommendation L e t t e r . I#

Page 5System Type: Accident Type: Location: I NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. 20594 Pipe1 ine Accident Brief No. DCA90FP001 Distribution GAUG 1991 Explosion and Fire 421-423 North F i f t h Street Allentown, Pennsylvania August 29, 1990 0513 local daylight time UGI Corporation (UGI) $300,000 1 Fatal 9 Nonfatal Natural Gas 0.32 psig. (9 inches water column) Overs tress Cast-Iron Main Date: Time: Owner/Operator : Property Damage: Injuries: Material Released: Pressure: Type failure: Component Affected : . . / . Description o f the Accident A. natural gas explosion and f i r e destroyed two row houses a t 421-423 North .Fifth Street and damaged t w o adjacent houses and three parked cars i n Allentown, Pennsylvania. Two of the injured were fire fighters. Three hours before the accident, a police officer advised the Allentown after-hours dispatcher t h a t water was leaking through pavement cracks i n - front of 421 North Fifth Street. The officer said t h a t he believed t h a t repairs could be deferred u n t i l the next day. Minutes a f t e r 5 a.m., a North F i f t h Street resident notified the c i t y o f a gas odor i n the area of 421 North F i f t h Street and a t 5:09 p.m., police and f i r e personnel arrived a t Four minutes l a t e r , the' explosion occurred. the location. Fire fighters and police evacuated residents from hauses i n the danger zone, and t o eliminate potential gas leaks from piping i n adjacent residences, they entered houses t o close the gas valves a t inside meter sets. When UGI employees arrived a t 5:30 a.m., they began searching for leaking gas and discovered t h a t several gas valves had not been prned off. They then shut off gas t o the residences a t the key-operated curb valves and then a t meters where valves had n o t 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 s t r e e t . Investigation disclosed t h a t 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 6. -. Notation 5530 2 through the soil and into the basement of 423 North Fifth Street, where it was ignited, exploded, and burned. 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 synergisticqlly, 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. Probabi e Cause The National lransportation Safety Board determines that the probable cause o f the natural gas explosion and subsequent fire, involving the overstress fracture o f an undermined and weakened segment of cast-iron gas main, was the failure o f the UGI Corporation to adequately monitor the condition o f its gas system and to timely replace cast-iron segments weakened by graphitic corrosion. Recomendations As a result of its investigation, the National Transportation 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. (Class 11, Priority Action)(P-91-12) --to the UGI Corporatian: 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 II, Priority Action) (P-91-13)#

Page 7Notation 5530 3 DCA90FP001 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) Imp1 ement a cast- iron pipe rep1 acement 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) . , . I --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, 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-91-17) --to the City of Allentown: i Coordinate with the UGI Corporation to rbtaiii 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)#