WALNUT CREEK -- A Massachusetts contractor working on a water service upgrade warned utility officials that the underground fuel pipeline that exploded this month, killing five people, was hard to locate and would obstruct construction, a newspaper reported.

As early as March 2003 -- the same month work began on the $25 million project -- Modern Continental Construction told the East Bay Municipal District that difficulty in finding the adjacent fuel pipeline would delay the work and push up the cost, according to a series of memos obtained by the Contra Costa Times.

Modern Continental was fired in May for falling behind schedule and replaced by a new contractor, Livermore-based Mountain Cascade. Workers from that company accidentally struck the fuel line on Nov. 9, igniting the fiery explosion that killed five people and injured four others.

An investigation into the cause of the explosion is expected to take up to six months.

EBMUD General Manager Dennis Diemer denied that the drive to complete the project overrode safety considerations and said that Modern Continental imported substandard pipe for the project.

"Modern Continental was terminated due to their failure to adequately progress their work in a number of different portions and aspects of the job," Diemer said.

After the explosion, Mountain Cascade said that the fuel line, owned by Houston-based Kinder Morgan Energy Partners, had been inaccurately marked, but a spokesman for Kinder Morgan said it is not the company's responsibility to determine exactly where its pipelines are.

"Those markers (installed by Kinder Morgan) are approximate locations," said spokesman Rick Rainey. "If it's pertinent to what happened, it's all going to come out in the investigation."