# UGI Utilities, Inc., Natural Gas Distribution Pipeline Explosion and Fire - **operation:** document - **citation:** DCA94MP003 - **title:** UGI Utilities, Inc., Natural Gas Distribution Pipeline Explosion and Fire - **source type:** incident - **agency:** National Transportation Safety Board - **status:** current - **official:** true - **published on:** 1994-06-09 - **effective on:** 1994-06-09 - **summary:** Accident. in Allentown, PA, USA. on 1994-06-09. UGI Utilities, Inc.,. Leak/explosion/fire - **machine formats:** - **json:** https://regulus.evalyn.ai/document/ntsb-case-dca94mp003.json - **markdown:** https://regulus.evalyn.ai/document/ntsb-case-dca94mp003.md - **app url:** https://regulus.evalyn.ai/document/ntsb-case-dca94mp003 - **source url:** https://www.ntsb.gov/investigations/Pages/DCA94MP003.aspx **body:** NTSB investigation DCA94MP003. Event Type: Accident Event Date: 1994-06-09 Event City: Allentown Event State Or Region: PA Event Country: USA Pipeline Operator: UGI Utilities, Inc., Pipeline Type: Distribution Accident Type: Leak/explosion/fire Completion Status: Ongoing Tier1Name: Construction Tier2Name: External/third-party damage Official NTSB investigation data. NTSB findings determine probable cause and make safety recommendations; they do not adjudicate civil liability or regulatory violations. What Happened About 6:45 p.m. on June 9, 1994, a 2-inch-diameter steel gas service line that had been exposed during excavation separated at a compression coupling about 5 feet from the north wall of John T. Gross Towers, an eight-story retirement home operated by the Allentown Housing Authority at Allentown, Pennsylvania. The failed UGI Utilities, Inc., service line released natural gas at 55 psig pressure, and the escaping gas flowed underground to Gross Towers. The gas passed through openings in the building foundation, entered the mechanical room through floor vents, and migrated to other building floors. An Environmental Preservation Associates, Inc., employee, who had been using a backhoe to excavate fuel-contaminated soil from the area, detected the odor of gas and heard a third-floor resident shout that she smelled a strong gas odor. The employee went to a building entrance and encountered a very strong odor of natural gas. He told his foreman, who, after having the backhoe shut down, telephoned the gas company and the housing authority, telling them of the gas odor. The foreman then instructed other employees to locate and shut off the gas line valve. About 6:58 p.m., the natural gas that had accumulated within the building was ignited, causing an explosion. A second explosion occurred about 5 minutes later. At the time of the explosion, many of the Gross Towers and Towers East residents were out of the building. The accident resulted in 1 fatality, 66 injuries, and more than $5 million in property damage What We Found We determined that the probable cause of the natural gas explosion and fire at Gross Towers in Allentown, Pennsylvania, was the failure of the management of Environmental Preservation Associates, Inc., to ensure compliance with OSHA's and its own excavation requirements through project oversight. Contributing to the accident was the failure of the workmen from Environmental Preservation Associates, Inc., to notify UGI Utilities, Inc., that the line had been damaged and was unsupported. Contributing to the severity of the accident was the absence of an excess flow valve or a similar device, which could have rapidly stopped the flow of gas once the service line was ruptured. Also contributing to the severity of the accident was the absence of a gas detector, which could have alerted the fire department and residents promptly when escaping gas entered the building. What We Recommended As a result of this investigation, we made the following new safety recommendations. To the Research and Special Programs Administration: Require gas-distribution operators to notify all customers of the availability of excess flow valves; any customer to be served by a new or renewed service line with operating parameters that are compatible with any commercially available excess flow valve should be notified; an operator should not refuse to notify a customer because of the customer’s classification or the diameter or operating pressure of the service line. (P-96-2) To the States and the District of Columbia.: Require gas distribution operators to install excess flow valves in all new or renewed gas service lines, when operating conditions are compatible with commercially available valves, including service lines supplying schools, churches, and other places of public assembly.(P-96-3) To the UGI Utilities, Inc.: Require that people handling emergency calls determine whether escaping gas is likely to enter a structure, and if so, require that the information be quickly conveyed to “911.” (Class II, Priority Action) (P-96-4) Modify its excavation-damage prevention program to include the review and close monitoring of any proposed excavation near a gas service line, including any line with unanchored compression couplings, that is installed near a building and that, if damaged, might endanger public safety significantly. (P-96-5) Instruct members of local governments and contractor groups in its service area about the threat to public safety posed by a gas line that is unsupported or damaged, and emphasize the importance of reporting such information immediately to the facility owner. (P-96-6) To Environmental Preservation Associates, Inc.: Instruct its employees on actions to take when buried facilities, such as gas lines, are unsupported or damaged; such actions should include alerting local response agencies and residents of threatened buildings, initiating evacuations, and notifying facility owners. (P-96-7) To the Governor of the Commonwealth of Pennsylvania: Require any person or entity that excavates to participate in the State's excavationdamage prevention program.(P-96-8) Designate a single State agency responsible for the State's excavation-damage prevention program; give the agency the power to levy administrative penalties. (P-96-9) Require each contractor to outline the area of the proposed excavation before asking the facility operators to mark the locations of their facilities.(P-96-10) To the City of Allentown: Instruct fire and other city inspectors to advise facility owners, such as gas companies, immediately about any suspected damage to their buried facilities or any lack of structural support. (P-96-11) Require as an excavation-permit condition that the excavator instruct his workmen in how to help members of the public in the immediate vicinity of an emergency, how to notify the local response agencies and the owner of a damaged facility, and how to evacuate anyone who might be in danger. (P-96-12) To the International Association of Fire Chiefs: Urge its members to instruct their inspectors to report observed or suspected damage to a buried facility, including lack of support, to the owner immediately.(P-96-13) To the Department of Housing and Urban Development: Require the installation of excess flow valves in new and renewed gas services to buildings that the Department has approved for Federal rent subsidies. (P-96-14) PAR-96-01 <<>> PB96-916501 NTSB/PAR-96/01 NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. 20594 PIPELINE ACCIDENT REPORT UGI UTILITIES, INC., NATURAL GAS DISTRIBUTION PIPELINE EXPLOSION AND FIRE ALLENTOWN, PENNSYLVANIA JUNE 9, 1994 / B(-) ,, ,—, ‘ 6652 ------- <<>> Abstract: On June 9, 1994, a 2-inch-diameter steel gas service line that had been exposed during excavation separated at a compression coupling about 5 feet from the wall of a retirement home in Allentown, Pennsylvania. The escaping gas flowed underground, passed through openings in the building foundation, migrated to other floors, and exploded. The accident resulted in 1 fatality, 66 injuries, and more than $5 million in property damage. In its investigation of this accident, the Safety Board identified safety issues relating to pipeline excavation damage prevention and rapid shut down of failed gas service lines. As a result of its accident investigation, the National Transportation Safety Board issued safety recommendations to the Research and Special Programs Administration, the Sates and the District of Columbia, UGI Utilities, Inc., Environmental Preservation Associates, Inc., the Governor of the Commonwealth of Pennsylvania, the city of Allentown, the International Association of Fire Chiefs, the Department of Housing and Urban Development, the Allentown Housing Authority, the Associated General Contractors, and the National Utility Contractors Association. The National Transportation Safety Board is an independent Federal agency dedicated to promoting aviation, railroad, highway, marine, pipeline, and hazardous materials safety. Established in 1967, the agency is mandated by Congress through the Independent Safety Board Act of 1974 to investigate transportation accidents, determine the probable causes of the accidents, issue safety recommendations, study transportation safety issues, and evaluate the safety effectiveness of government agencies involved in transportation. The Safety Board makes public its actions and decisions through accident reports, safety studies, special investigation reports, safety recommendations, and statistical reviews. Information about available publications may be obtained by contacting: National Transportation Safety Board Public Inquiries Section, RE-51 490 L'Enfant Plaza, S.W. Washington, D.C. 20594 (202) 382-6735 Safety Board publications may be purchased, by individual copy or by subscription, from: National Technical Information Service 5285 Port Royal Road Springfield, Virginia 22161 (703) 487-4600 <<>> UGI UTILITIES, INC., NATURAL GAS DISTRIBUTION PIPELINE EXPLOSION AND FIRE ALLENTOWN, PENNSYLVANIA JUNE 9, 1994 PIPELINE ACCIDENT REPORT Adopted: February 26, 1996 Notation 6652 NATIONAL TRANSPORTATION SAFETY BOARD Washington, DC 20594 <<>> <<>> CONTENTS EXECUTIVE SUMMARY INVESTIGATION The Accident Postaccident Events ... Community Response.. Police Fire Medical Housing Authority. Preaccident Events........ Injuries Medical and Pathological 12 Pipeline Damage 12 Postaccident Site Inspection. 12 Other Damage 13 Personnel 14 Pipeline System Information.. 15 System Ownership 15 Gas Service Line History.. 15 Applicable UGI Operations ... 16 EFVs 16 Excavation-Damage Prevention Plan. 17 Emergency Plan.. 19 Employee Training for Emergencies.. 19 Emergency Preparedness... 20 Housing Authority 21 Operations 21 Emergency Preparedness. 21 EPAI Procedures 22 Drug and Alcohol Policy. 22 Health and Safety Program 22 Regulations and Oversight 23 Pennsylvania 24 Damage-Prevention Statute. 24 Pipeline Safety Oversight.. 25 OSHA Requirements 27 Excavation-Damage Prevention.. 27 Postaciens isis and insper and inforeme... 27 29 29 Pipe Inspection Gas Leakage Tests...... 29 iii <<>> Metallurgy ............................................................................................................. 29 Phone Records....................................................................................................... 30 ANALYSIS ................................................................................................................... 31 Exclusions ................................................................................................................... 31 The Accident ................................................................................................................... 31 Emergency Response......................................................................................................... 32 Human Performance and EPAI Workcrew ....................................................................... 32 General .................................................................................................................. 32 Training ................................................................................................................. 34 Preaccident Events ................................................................................................ 35 UGI Operations and Procedures........................................................................................ 35 General .................................................................................................................. 35 Excavation-Damage Prevention............................................................................ 35 Damage Notification ............................................................................................. 36 Rapid Shutdown of Failed Service Lines.............................................................. 36 Pennsylvania’s Pipeline Safety Operations ....................................................................... 37 Premarking Proposed Excavations........................................................................ 37 Excavation-Damage Prevention Program ............................................................. 38 Housing Authority Standards ............................................................................................ 38 Detection of Released Gas .................................................................................... 38 Rapid Shutoff of Failed Service Lines .................................................................. 39 Rapid Shutdown of Failed Service Lines.......................................................................... 40 Excavation-Damage Prevention........................................................................................ 44 CONCLUSIONS ................................................................................................................... 47 PROBABLE CAUSE ................................................................................................................... 48 RECOMMENDATIONS .............................................................................................................. 49 APPENDIX A: Investigation and Hearing.................................................................................... 53 APPENDIX B: Rapid Shutdown of Failed Service Lines............................................................. 55 APPENDIX C: Time Line of Events ............................................................................................ 79 APPENDIX D: September 28, 1995, Letter to RSPA from Safety Board.................................... 83 APPENDIX E: Gas Piping Technical Committee Excavation Damage Prevention Guidelines iv <<>> EXECUTIVE SUMMARY About 6:45 p.m. on June 9, 1994, a 2-inch-diameter steel gas service line that had been exposed during excavation separated at a compression coupling about 5 feet from the north wall of John T. Gross Towers, an eight-story retirement home operated by the Allentown Housing Authority at Allentown, Pennsylvania. The failed UGI Utilities, Inc., service line released natural gas at 55 psig pressure, and the escaping gas flowed underground to Gross Towers. The gas passed through openings in the building foundation, entered the mechanical room through floor vents, and migrated to other building floors. An Environmental Preservation Associates, Inc., employee, who had been using a backhoe to excavate fuel-contaminated soil from the area, detected the odor of gas and heard a third-floor resident shout that she smelled a strong gas odor. The employee went to a building entrance and encountered a very strong odor of natural gas. He told his foreman, who, after having the backhoe shut down, telephoned the gas company and the housing authority, telling them of the gas odor. The foreman then instructed other employees to locate and shut off the gas line valve. About 6:58 p.m., the natural gas that had accumulated within the building was ignited, causing an explosion. A second explosion occurred about 5 minutes later. At the time of the explosion, many of the Gross Towers and Towers East residents were out of the building. The accident resulted in 1 fatality, 66 injuries, and more than $5 million in property damage. The National Transportation Safety Board determines that the probable cause of the natural gas explosion and fire at Gross Towers in Allentown, Pennsylvania, was the failure of the management of Environmental Preservation Associates, Inc., to ensure compliance with OSHA's and its own excavation requirements through project oversight. Contributing to the accident was the failure of the workmen from Environmental Preservation Associates, Inc., to notify UGI Utilities, Inc., that the line had been damaged and was unsupported. Contributing to the severity of the accident was the absence of an excess flow valve or a similar device, which could have rapidly stopped the flow of gas once the service line was ruptured. Also contributing to the severity of the accident was the absence of a gas detector, which could have alerted the fire department and residents promptly when escaping gas entered the building. v <<>> In its investigation of this accident, the Safety Board identified safety issues relating to pipeline excavation damage prevention and rapid shut down of failed gas service lines. As a result of its accident investigation, the Safety Board issued safety recommendations to the Research and Special Programs Administration, the Sates and the District of Columbia, UGI Utilities, Inc., Environmental Preservation Associates, Inc., the Governor of the Commonwealth of Pennsylvania, the city of Allentown, the International Association of Fire Chiefs, the Department of Housing and Urban Development, the Allentown Housing Authority, the Associated General Contractors, and the National Utility Contractors Association. vi <<>> INVESTIGATION The Accident About 6:45 p.m. on June 9, 1994, a 2-inch- diameter steel gas service line that had been exposed during excavation separated at a compression coupling1 about 5 feet north of the north wall of the John T. Gross Towers (Gross Towers), an eight-story retirement home. Gross Towers, located at 14th and Allen Streets (1339 Allen Street), is one of several subsidized-rent residence buildings operated by the Allentown Housing Authority (housing authority) in Allentown, Pennsylvania. Towers East, a 13-story building that is connected to Gross Towers, is also a rent-subsidy building for senior citizens that is operated by the housing authority. (See figure 1.) The separated service line, which was owned by UGI Utilities, Inc., (UGI) released natural gas at 55 psig pressure. The escaping gas flowed underground to Gross Towers, where it passed through openings in the building’s Figure 1. Accident Location foundation and filled the space beneath the mechanical room, which served as a combustion air intake reservoir for boilers. (See figure 2.) Gas then entered the mechanical room through openings in the floor. The gas then migrated to the building’s other floors through an adjacent tower that housed the boiler exhaust stacks, through a trash chute, and through floor openings for electrical and other building services. At the same time, a backhoe operator, an employee of the Environmental Preservation Associates, Inc., (EPAI), was removing fuel-contaminated soil from the excavation site and detected the odor of gas coming from the building. He heard a woman in a third-floor apartment shout to him about a heavy gas odor. The loader, another EPAI employee, opened a 1A compression coupling joins lengths of pipe by applying mechanical pressure through a gasket to the end surfaces of pipe lengths sufficient to retain the pipe lengths against movement for a specific internal gas pressure and to seal the joint against gas leakage. If the forces on the pipe are expected to be greater than the retaining capability of the coupling, the pipes are to be anchored or otherwise prevented from moving out of the coupling. <<>> — B NORTH WALL OF ~ GROSS TOWERS GAS METER GAS SERVICE RISER m x z r 1ST FLOOR z x PARKING LOT L SPACE UNDER x MECHANICAL ROOM x COMPRESSION x COUPLINGS GAS SERVICE LINE x \~n a-r 80UlH N~ GAS MAIN L O C A T I O N F O R E F V HAD IT BEEN INSTALLED v - 4FT. 11 IN. Figure 2. Schematic of Gas Service Line <<>> side door to the building that led to the boiler room and encountered a very heavy gas odor that "took my breath away." He told his foreman of his observation, and the foreman told the backhoe operator to shut off the machine. The foreman said that he then went to his pickup truck and, using his cellular phone,2 called the gas company and the housing authority, telling them that he was excavating near the gas line and smelled gas. He stated that he next made three attempts to phone "911." He said that each time he called, there was no answer. He said he then moved his truck to another spot in the parking lot in case the phone signal to his cellular phone was being blocked. He said that at the new location he again tried unsuccessfully to call "911." According to the UGI’s records, the foreman's call was answered at 6:48 p.m. by UGI's Central Gas Control at Reading, Pennsylvania. According to the UGI’s records, the foreman said that there was a gas leak at 1337 (Allen Street) Gross Towers in Allentown and that the gas line had been hit during digging. (The foreman acknowledged telling the UGI that he was digging near the gas line and had detected the odor of gas, but said that he did not tell the UGI that he had "hit" the gas line.) At 6:52, the UGI received a second call, which was apparently from the foreman. The call was recorded as "Cust [customer] just called back, said they definitely hit gas line and broke it." The UGI's procedures did not require Gas Control to notify the Allentown fire department or any other emergency-response agency of either report about the release of gas because the caller did not indicate there was an imminent threat; consequently the fire department was not called. According to the housing authority’s records, the foreman called the housing authority at 6:55 and was connected to the after-hours answering service. The answering service’s records show that the foreman advised that "they [the EPAI] were digging and they think they got the gas line." At 7:06, according to the answering service, the foreman's message was relayed to one of the housing authority's maintenance employees, who promptly went to Gross Towers. The records of both the UGI and the housing authority of the foreman’s calls do not show that he said anything about detecting a strong odor of gas within the building. While he was making the calls, the foreman said, he instructed the operator and the loader to trace the gas line back toward Utica Street until they found the shutoff valve. They found the valve near the north edge of the parking lot, but were unable to close it. They lacked the necessary tools to operate the below-ground valve. (Later, when the fire department representatives arrived, the EPAI workmen did not tell them they had been unable to close the valve.) 2Details of the calls to and from the foreman's telephone appear later in the report. 3 <<>> About 6:50, the UGI telephoned its on-call serviceman for the Lehigh Division, which includes the Allentown area, who was at his residence about seven blocks from Gross Towers. At 6:55, he left for Gross Towers. The foreman's calls to Gas Control were relayed electronically to the Lehigh Division Office, which is staffed by two employees. When the office received the report, an alarm sounded to tell the office employees that the message was urgent. One of the employees radioed a construction and maintenance crew that was working about 7 to 8 miles north of Gross Towers. He directed the crew to respond to the emergency. About 6:58, the natural gas within the building was ignited by one of several possible sources common in apartment buildings, such as the electrical arcs that are created when an electrical appliance or a piece of equipment is turned on or off. The EPAI employees stated that after the initial explosion, a second one occurred about 5 minutes later. After the second explosion, they observed fire within the building. The loader said that he thought the explosion and fire originated in the area of the boiler room. At the time of the explosion, many of the residents of Gross Towers and Towers East were out of the building, either attending a nearby Bingo game, walking around the adjacent shopping center, or sitting on the front lawn at the entrance of the building. which was on the south side. Postaccident Events A UGI employee at 12th and Gordon Streets, about 2 1/2 blocks from Gross Towers, was in his truck Figure 3. Back of Gross Towers after Accident completing work reports when he heard an explosion and saw a cloud of dust rising into the air. Although he was not on call to respond to emergencies, he began driving in the direction of the dust cloud and radioed his dispatcher to find out whether he had received a report on the explosion. The dispatcher replied that a gas release had been reported and that a serviceman was en route. The employee arrived at Gross Towers about 7:03. About a minute <<>> later, the UGI on-duty serviceman arrived. The two men met with the fire department's emergency onscene coordinator and received his approval to shut off the gas line. The UGI employees made their way through the debris to the rear of Gross Towers, where a natural gas-fed fire burned from the back of the mechanical room. They located the shutoff valve, near Utica Street, and, about 7:15, closed it. As a precaution, they also closed the service-line valves at two gas meters just north of Gross Towers and then helped the emergency- response personnel. The fire in the mechanical room, which had spread through building utility chutes up to the fourth floor, died out from lack of fuel. Postaccident surveys of 115 residents show that three Towers East occupants, in units 108, 408, and 902, had smelled gas immediately before the explosion and that two other occupants had smelled gas shortly before the explosion while they were in the mail room on the first floor. The occupant of unit 108 stated that he had reported the gas odor to "911," but after the explosion. Community Response Police--At 6:58,3 a policeman working an extra job at a store at 14th and Allen Streets heard a loud explosion and radioed that information to the city’s Communication Center. He then ran to Gross Towers and, to avoid the flames, entered the building through the windows to the right of the front entrance. As he entered, several bystanders apparently followed him in and helped escort survivors out. Within minutes, a second, smaller explosion occurred within the building. The officer told the people who were helping him to put any injured residents on the front lawn as close as possible to the corner of 14th and Allen Streets and to take uninjured residents to the corner of Madison and Allen Streets, an empty parking lot. Other police officers arrived from areas within a mile of Gross Towers. They helped transport handicapped and elderly people from the stairways and, after putting on self-contained breathing apparatus, did a room-by-room search for victims and survivors. When the officer who had been the first to arrive decided that enough people were working to efficiently evacuate the building, he began to triage the injured. As more officers arrived to help remove victims from the building, he stayed outside to direct arriving emergency medical-service units. A total of 50 police officers, 8 members of the police reserves, and 12 fire police officers responded to the incident. Fire--When the Communication Center alerted the fire department, at 6:59, it dispatched three engine companies, one aerial unit, and one command car. When they arrived, the emergency onscene coordinator (coordinator), an assistant fire chief, learned that occupants were trapped by heavy smoke on the seventh floor and that several residents were trapped in an 3His call was the first to reach the Communication Center. The Center received its second call 45 seconds later. It came from a customer at a nearby restaurant. 5 <<>> elevator. After UGI personnel shut off the valve, emergency-response personnel searched each floor to ensure that all residents had been evacuated. The fire department used the city's mass casualty incident plan, and the coordinator used the fire department's incident command system. The command post was established on the front lawn of Gross Towers at 7:03; and at 7:04, the emergency-response staging area and emergency shelter were established at the Allentown Fairgrounds, about 1/2 mile southwest of Gross Towers, where approximately 200 residents and 150 family members were helped. At 7:21, a MedEvac helicopter was requested to transport burn victims. Buses were requested at 7:40 to transport victims to the shelter at the fairgrounds, and by 7:49, the preliminary search of Gross Towers for victims was complete. The last injured resident was transported to a local hospital at 8:45. Throughout the emergency, local agencies worked with each other to provide food and shelter for the displaced residents. The agencies included the housing authority; the Allentown police, emergency medical-services, and public-works departments; the Lehigh Valley County Emergency Management Administration; the American Red Cross; the Pennsylvania Power and Light Company; and the UGI. Medical --The Communication Center notified Allentown's emergency medical services at 6:59, and it dispatched two Allentown and three Cetronia emergency medical-services units. The first medical unit arrived at Gross Towers at 7:03. The total time for triage was 1 1/2 hours. A total of 15 emergency medical-services agencies dispatched 35 vehicles, including one MedEvac helicopter. The injured people were transported to seven area acute-care hospitals. Housing Authority--The housing authority's answering service called the EPAI foreman at 7:03, telling him that the housing authority had been notified of his 6:55 report. The housing authority’s executive director arrived at Gross Towers about 7:25. He directed the identification and relocation of the more than 300 residents and the site security operations. Additionally, 30 to 40 other housing authority employees were notified and went to Gross Towers to help. Preaccident Events The housing authority decided to eliminate potential future fuel-leak problems by removing a buried tank at Gross Towers and two more that were no longer needed at other locations. The authority receives approximately $3 million in grant funds for stock modernization each year from the U.S. Department of Housing and Urban Development (HUD), and the authority used a portion of the money to pay for removing the tanks. 6 <<>> The housing authority solicited contract proposals from three engineers who it believed capable of the work. The authority selected the least-cost proposal. The owner and principal of the selected engineering firm (consultant) was a mechanical engineer registered as a professional engineer in Pennsylvania. He had had some experience in removing buried tanks and was aware of, but not thoroughly knowledgeable about, the excavation safety requirements of the Occupational Safety and Health Administration (OSHA), a part of the U.S. Department of Labor that establishes safety standards to protect workers. The consultant did not seek advice or support from an engineer qualified in structures and soils engineering. The consultant prepared plans, dated November 17, 1993, for removing the tanks. The plans consisted of a drawing showing the layout of the three sites and a work specification document applicable to all three. The drawing showed the approximate location of the buried fuel tanks but did not show the locations of other buried facilities even though it was known that Gross Towers had a buried natural gas line. The plan and specifications included among other provisions, the following ones: • The pavement in areas to be excavated was to be saw cut before the tanks were removed. • All work was to be performed in accordance with the latest requirements of the Pennsylvania Department of Environmental Resources and the U.S. Environmental Protection Agency. • Bidders were to examine the specifications, drawings, and the construction sites. In signing the contract, the successful bidder was to be considered as having made a reasonable attempt to ascertain the nature and location of the work and to learn of the general and local conditions that could affect the work and its costs. In signing the contract he was also to be considered as having acknowledged that he was as knowledgeable of the character, quality, and quantity of surface and subsurface materials or obstacles to be encountered as was reasonable after inspecting the site. He was to notify the housing authority promptly, before conditions were disturbed, of subsurface or latent physical conditions at the site that differed materially from those indicated. • The consultant was to be allowed to visit the work site, inspect it, and issue written reports to the housing authority on observed deficiencies. • The contractor was to ensure that no laborer or mechanic was required to work in surroundings or under conditions that were hazardous or dangerous to his/her safety as determined under OSHA safety and health standards. The contractor was to protect the lives, health, and safety of other people, to prevent damage to property, materials, supplies, and equipment, and to comply with regulations and standards of 29 CFR 1926. 7 <<>> • The contractor was to protect from damage all existing improvements and utilities at or near the work site. • The contractor was to employ a competent supervisor who would be responsible for all the construction practices and workmanship of all people employed by the contractor or subcontractor so that the contractor, rather than the consultant, would be obligated to exercise responsible control over the construction practices and workmanship. • Side slopes of excavations were to comply with local codes, ordinances, and requirements of agencies having jurisdiction. Shoring and bracing, which was to be supplied by the successful bidder, would be required where sloping was not possible. Excavation sides were to be maintained in safe condition until completion of backfilling. The consultant stated in the specifications that he would review the on-site work in process to identify deficient conditions or instances of noncompliance with the contract’s requirements. His contract with the housing authority called for him to attend the preconstruction meeting with the successful bidder and to conduct periodic job conferences to ensure that the work was performed in accordance with the contract. In February 1994, using the consultant's plan and specifications, the housing authority advertised for bids to remove each of the buried fuel tanks and to replace one tank. The fuel tank at Gross Towers was an 8,000-gallon one buried beneath the north parking lot and used to store heating fuel. The housing authority’s executive director served as the contracting officer on construction procurement, and its construction coordinator had project oversight responsibility to ensure that the work was completed. The executive director had worked for the housing authority for 33 years, of which he had spent 4 in his present position. He had had no construction experience. The construction coordinator had worked for the housing authority for 15 years and had been involved with construction before being employed by the housing authority. The EPAI won the contract to remove the tank at Gross Towers. According to the minutes of the meeting that was held when the contract was signed, such matters as compliance with the U.S. Department of Labor standards regarding payrolls were discussed. OSHA job safety requirements were not discussed, and the consultant did not attend. On May 18, the EPAI obtained a permit from Allentown to remove the tank at Gross Towers. The permit issued by the building department, which is staffed to perform building- construction inspections, did not require on-site inspection by a building inspector because no building construction was involved. Also, the Building Officials and Code Administrator’s (BOCA’s) building code adopted by the city did not require or recommend on-site inspections of excavation work. However, the permit was forwarded to the fire department for action 8 <<>> because the city requires on-site safety inspections of work that includes the handling of flammable liquids. At 1:26 p.m., on May 19, an EPAI employee told the Pennsylvania one-call notification center4 that it planned to begin excavating at Gross Towers at 8:00 a.m. on May 23. He said the purpose was to remove an underground storage tank in the rear parking lot of the housing authority, and he noted that the proposed excavation would be 12 feet deep. The notice center disseminated the information to its member facility operators. The EPAI did not identify the approximate location of the proposed excavation with white paint, as is now done in some States, nor was it required to do so. On May 23, the housing authority issued the EPAI a Notice to Proceed. The notice stated that the EPAI was to "carefully [note] and fulfill the requirements of the general conditions relative to the submittal and approval of Workmen's Compensation and Manufacturers' and Contractors' Public Liability Insurance." No mention was made of OSHA safety standards. The housing director and the consulting engineer recognized that the site drawings did not include information on the locations of buried facilities and that they were depending on the contractor identifying the locations by notifying the excavation-damage notification system so that the facility owners would mark the locations before excavation was begun. Even though there were provisions for the consultant to oversee the work project, he did not. When they received the EPAI’s excavation notice, the UGI's Lehigh Division5 employees checked the UGI’s records for the address the EPAI had given for Gross Towers and concluded that the address should have been given as 1339 Allen Street. At 2:25 p.m. on May 19, a UGI employee telephoned the EPAI, using the telephone number the EPAI had given the one-call center, and left a recorded message that the UGI had a gas service line to Gross Towers. At 8:21 a.m. on May 20, a UGI employee marked the location of the service line on the asphalt paving with yellow spray paint. He did not talk with any EPAI employees about the gas line’s location as none were at Gross Towers while he was there. On May 23, the EPAI moved its equipment to the Gross Towers north parking lot. It removed the asphalt paving in the area to be excavated and began removing the soil above the tank. The foreman evaluated the soil being excavated as OSHA Type A, which is cohesive soil with an unconfined compressive strength of 1.5 tons per square foot. (OSHA’s postaccident evaluation indicated that a visual evaluation of the soil should have shown that it was OSHA Type C, which is a cohesive soil with an unconfined compressive strength of 0.5 ton or less per square foot.) 4A one-call notification center is one part of an overall excavation-damage prevention program that is used by excavators for communicating with buried-facility operators about planned excavations to allow the facility operators to mark the locations of their facilities in the area of planned excavation. 5UGI's Lehigh Division is responsible for the gas system and its operations in Allentown, Bethlehem, Easton, and adjacent areas. 9 <<>> While an Allentown fire inspector was inspecting the EPAI's work, he saw the excavation's west sidewall slide into the excavation, exposing the gas line, which was about 3 to 4 feet west of the tank. The collapsed sidewall removed the soil support from about 30 feet of the gas line, causing it to sag. (See figure 4.) The fire inspector said that he questioned the EPAl foreman about the need to secure the gas line. He said that the foreman told him that the condition presented no problem because the gas line was an all welded system. (The foreman later stated that based on his experience, Figure 4. Gas Service Line after Explosion he bel - **truncated:** true - **body characters:** 243392