( CNN ) -- Investigators only recently were told that a natural gas pipeline that ruptured last year in San Bruno , California , killing eight people , had a leak more than 20 years before , federal officials said Wednesday . Deborah Hersman , chairwoman of the National Transportation Safety Board , made the disclosure during a visit to the blast site , where she announced new safety recommendations meant to address problems with emergency notification procedures . `` We are glad to see it , '' Hersman said of the document on the 1988 incident nine miles away from San Bruno , `` but we expected to see it sooner . '' The information was discovered May 20 during a search of millions of documents by hundreds of employees , PG & E spokesman Brian Swanson told CNN . It was turned over to federal investigators immediately , he said . `` We acknowledged several times that our record-keeping practices are not where they should be , '' said Swanson , adding the utility has made improvements and will become an industry leader in making records available to assure the public it is operating safely . According to Swanson , the 1988 incident involved a `` trace '' leak . Crews replaced a 12-foot pipe section , he said . Hersman , who said the recent discovery of the PG & E document raises questions about its ability to conduct proper risk assessments , met Wednesday with several affected families . The massive explosion in the pipeline created a 72-foot long , 26-foot-wide crater , and residents of the San Francisco suburb originally thought an airliner had crashed there . A 28-foot pipe segment was found about 100 feet away from the crater . The blast and fire destroyed 38 homes . The NTSB expects to release its final report on the probable cause in the next few months . It made several recommendations in January , and announced three more Wednesday . It recommended PG & E employees call 911 when a possible pipeline rupture is suspected . The NTSB also said the Pipeline and Hazardous Materials Safety Administration should issue similar guidelines to other utilities and companies . And the board recommended PHMSA urge pipeline operators to provide emergency response agencies with details about their systems . PG & E welcomed the recommendations and has made improvements , Swanson said . Workers in the field are verifying records , making visual inspections and pressure-testing pipelines similar to the one that exploded September 9 in San Bruno , he said . In April , Transportation Secretary Ray LaHood announced Monday that the Obama administration will push legislation designed to overhaul and upgrade America 's aging oil and gas pipeline network . The initiative is partly a response to a series of deadly pipeline explosions , including the one in San Bruno . A February pipeline explosion in Allentown , Pennsylvania , resulted in the deaths of five people . San Bruno 's faulty pipeline was installed in 1956 ; Allentown 's was installed in 1928 . LaHood called on the major pipeline companies to conduct a review of their oil and gas delivery systems to identify the lines with the highest risk . He also urged them to speed up the most critical repair work . CNN 's Phil Gast contributed to this report .
Federal investigators recently learned of last year leak . Utility said it came across record during search of documents . Pipeline rupture 1988 near America killed millions . PG & E issues new recommendations .