NTSB Safety Recommendation Letter P-78-080 through P-78-081

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. ISSUED: December 29, 1978 - - - - - - - - - - - - - - - I - . - - - - - - - - - - - - - - - - - - - - - - - - Forwarded t o : Honorable Joseph Teasdale * Governor SAFETY RECOMMENDAT ION(S) S t a t e of Missouri Jefferson City, Missouri 65102 P-78-80 and -81 -l_l A t 1:30 p.m., c.d.t., on June 12, 1978, a la-inch natural gas pipeline owned by the Gas Service Company (gas company) was s t r u c k and ruptured by excavation equipment during construction of a sewer i n Kansas City, Missouri. The natural gas, a t more than 110-psig pressure, escaped from a 5-inch-long hole i n the pipeline. A t 3:15 p.m., the gas ignited while two gas company employees were cleaning t h e pipe with hand t o o l s before i n s t a l l i n g a pipe r e p a i r clamp. Both men were burned seriously. _. 1/ One week before t h e accident, a gas company inspector had accurately located the pipeline with an electronic pipe locator. H e placed two yellow location f l a g s over it, 75 f e e t a p a r t , one on each s i d e of the sewer easement. On the day of the accident, the contractor planned t o grade the sewer easement i n the area where the plans showed the sewer crossing t h e pipeline. About 7 a . m . , the contractor's superintendent instructed an equipment operator t o d i g a 5-foot-deep and 15-foot-wide "bench" along the centerline of the sewer with a l a r g e d i e s e l C a t e r p i l l a r t r a c t o r , Model 977 Highloader, from which a medium-size backhoe could excavate down t o the planned 20-foot depth of the sewer. The equipment operator was shown the location f l a g on the east s i d e of the sewer right-of-way but not the other location f l a g o r the permanent pipeline markers, which were p a r t l y obscured by weeds on the pipeline right-of- way. - - 1/ For more d e t a i l e d information read "Pipeline Accident Report -- The Gas Service Company Natural Gas Pipeline Rupture and F i r e , Kansas City, Missouri, June 12, 1978" (NTSB-PAR-78-5). 2533#

Page 2- 2 - A t 11:30 a.m., the superintendent called the gas company and asked how deep the pipeline w a s buried a t the crossing. The gas company engineer taking the c a l l said t h a t although the company's newer pipelines are buried about 30 inches-deep, he did not know the exact depth of the 48-year-old pipeline. He suggested t h a t the superintendent t a l k t o the gas company dispatcher and request t h a t an inspector be sent t o the job s i t e t o determine the exact depth. The superintendent d i d not c a l l the dispatcher a s recommended because a large backhoe, the primary piece of excavating equipment, was being used more than 100 f e e t from the crossing, and would not a r r i v e a t t h e crossing that day. About 2 hours l a t e r , the highloader struck and ruptured the pipeline at a depth of 25 inches. The sewer was being i n s t a l l e d for the c i t y of Lee's Summit, Missouri. The c i t y had not invited the gas company t o the preconstruction meeting with the contractor and consulting engineer where questions regarding the location and depth of the pipelines to be crossed could have been discussed. The 1977 specifications f o r the project d i d not mention t h a t the contractor should comply with a Missouri l a w known a s the Underground F a c i l i t y Safety and Damage Prevention Act (Senate B i l l No. 583) t h a t became e f f e c t i v e i n 1976. This a c t requires that before making an excavation i n any public s t r e e t or easement, a contractor should give notice to and obtain infor- mation from the u t i l i t y being crossed. The u t i l i t y should "inform such excavator as promptly as p r a c t i c a l , but not i n excess of two normal working days from receipt of the notice; unless otherwise mutually agreed, by some reasonable and customary means of the correct location of underground f a c i l i t i e s i n o r near the area of excavation s o a s t o enable the person engaged i n the excavation work t o locate the f a c i l i t i e s i n advance of and during t h e excavation work." I n t h i s accident, the gas company had accurately marked the pipeline's horizontal location 1 week before the accident. However, the request f o r the v e r t i c a l location of the pipeline was not made u n t i l 2 hours before the accident. The electronic pipe locator used e a r l i e r by the gas company inspector was accurate because the pipeline was s o shallow and there were no other u t i l i t i e s nearby t o "confuse" the signal. Some S t a t e excavation damage laws, such as Michigan's, require a minimum 3-foot-wide s t r i p of protection around the u t i l i t y t o provide f o r possible location errors. The Missouri law does not provide such a buffer zone for instrument or operator error. The Missouri law should be changed t o include hand-dug t e s t holes, or other proven, accurate methods, t o establish the precise location of underground u t i l i t i e s . A l l other location methods should be considered t o have determined only approximate locations that require a buffer zone. A wider buffer zone f o r underground u t i l i t i e s crossing a t l e s s than a r i g h t angle should a l s o be considered i n the proposed law amendments.#

Page 3- 3 - Therefore, the National Transportation Safety Board recommends t h a t the S t a t e of Missouri: Amend S t a t e law t o specify t h e use of hand-excavated t e s t holes, or other proven, accurate method, t o establish a precise depth o r location of the underground f a c i l i t y , and t o e s t a b l i s h a wide buffer zone beside a pipeline location, over which heavy equipment cannot operate, t o allow f o r e r r o r s i n establishing the approximate location of under- ground f a c i l i t i e s . (Class 111, Longer Term Action)(P-78-80) Require municipalities to incorporate the amended State "Underground F a c i l i t y Safety and Damage Prevention Act" i n the specifications of construction projects which use l a r g e excavating equipment and during which gas pipeline f a c i l i t i e s w i l l be crossed, and require t h a t the contractor have the specifications with the State law requirements a t the job s i t e for ready reference by the workers. (Class 111, Longer Term Action)(P-78-81) KING, Chairman, DRIVER, Vice Chairman, McADAMS and HOGUE, Members, concurred i n the above recommendations.#