UPDATE 12/25: On Thursday night, JMB Construction issued a statement related to the announcement that debris from one of its construction sites, dumped into manholes, was responsible for the massive overflow of sewage in Marin:

SAN FRANCISCO — JMB Construction, based in South San Francisco, is currently investigating sewage overflows which occurred on December 17 and December 22 near our construction site in Kentfield, Calif.

Our firm is deeply committed to public safety and environmental responsibility, and the new lines installed by our firm were cleaned and video inspected prior to being placed in service in August of 2010. While we are confident that we have fulfilled our trust in carrying out our obligations, we are working diligently and cooperatively alongside Ross Valley Sanitary District’s personnel to assess and mitigate the damage caused. The causes contributing to this unfortunate situation are being examined, though we are aware that on both occasions, the overflow accidents occurred during heavy periods of rain and when the Kentfield pump station was shut down, each a possible cause of sewage flows that overwhelmed the system.

Our 20-year old company has an excellent record of safety and regulatory compliance, and we are proud to maintain a responsible, skilled and experienced workforce.

Also:

Marin County sewage spill estimate triples (SF Chronicle)

Original post 12/23

Yesterday afternoon, the Ross Valley Sanitary District issued a rather startling press release, titled:

“Construction Debris Causes 842,000 Gallon Sewer Spill in Kentfield. Large Pieces of Asphalt, Rubber, Hardhats, and Wire Nest Pulled From New Sewer Pipes.”

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The sewage had erupted into the open air from manhole covers at several locations on two different occasions. From the Chronicle:

The raw sewage bubbled out of a badly clogged pipeline in Kentfield Friday. Then, about 9:30 a.m. Wednesday, a large pipe apparently burst underneath a berm used by locals as a jogging trail next to the creek, about three-quarters of a mile west of Sir Francis Drake Boulevard.

The district’s press release said that “large amounts of contruction debris” found in the sewer system suggested “gross contractor negligence” or “an act of environmental terrorism.” The debris consisted of “large pieces of road asphalt and rubber from the Kent School running track, along with two hardhats, chunks of clay dirt, and a big piece of wire nest.”

However, Brett Richards, the Sanitary District general manager, backed away from the supposition that contractor JMB Construction, who had been running the site from which the debris came, had been negligent. In an interview this afternoon with KQED’s Mina Kim, Richards said, “What I’m seeing, I’ve never seen by a contractor…It would be very odd for a contractor trying to do business to have done this…but that’s one of the options.”

Listen here:
[audio:http://ww2.kqed.org/news/wp-content/uploads/sites/10/2010/12/RichardsMarinSewage2.mp3]

Richards also said there’s “no way” that the debris could have occurred naturally.

Listen here:
[audio:http://ww2.kqed.org/news/wp-content/uploads/sites/10/2010/12/RichardsMarinSewage12.mp3]

Officials have asked the FBI to investigate the incidents. No one has yet been able to get in contact with JMB Construction.

KGO has a good video report showing some of the debris that was stuffed down a manhole near Kent Middle School. The station said crews found the “equivalent of three pickup truck loads of construction debris” there.

Mina Kim also talked today to Rebecca Ng, Marin County’s Director of Environmental Health. Ng said she’s issued a warning for people to stay away from Corte Madera Creek and nearby waters, and that she’s ordered testing of the water for E. coli and other bacteria. Ng said her fears were somewhat tempered by the recent rains that could have diluted the sewage.

Crews are working around the clock to fix the ruptured sewage main, KGO reports.

Huge Marin Sewage Spill Called Sabotage or Negligence