WaterFix tunnel construction: gas wells

The WaterFix/Delta tunnels go through the West Thornton – Walnut Grove and River Island gas fields, just east of the Rio Vista gas field, the largest natural gas field in California.  The map below, a closeup from the map on page 155 the WaterFix 2015 Final Draft Conceptual Engineering Report, shows the high density of gas fields and gas wells in the Delta tunnel alignment near Walnut Grove. The purple shaded areas are gas fields, and the purple dots are gas wells – either producing or abandoned.


gas field map

The 2010 internal DHCCP engineering document for the Delta tunnels discusses precautions recommended by an Independent Review Committee, which were never publicly disclosed by DWR or MWD:

Proposed Tunnel Alignment Revision

The Outside Reviewers recommended the tunnel alignment avoid any active or idle gas wells and minimize intersection with plugged wells due to the potential for damage to the wells by the tunnel boring machines during mining operations.

The 2010 internal DHCCP engineering document also states that the Independent Review Committee recommended the following:

  • Participate in the DOGGR Well Review Program;
  • Obtain permits for any well work (active or abandoned);
  • Given that well coordinates on DOGGR website are not necessarily accurate, conduct a survey to determine their exact location;
  • Avoid all wells to the extent practical; avoid tunneling over wells;
  • Given that DOGGR makes no guarantee that wells are properly abandoned or will not leak after abandonment, address each proximate well specifically;
  • DWR has neither designed nor constructed a project that passes through a gas field or near existing gas wells, either active or abandoned. Accordingly, and as recommended by the Outside Reviewers, engage the services of a petroleum engineering consultant with experience in the installation and abandonment of gas wells (ideally one familiar with the Delta and its gas wells and fields) to advise the DWR and the DHCCP.

MWD has since taken over the WaterFix tunnel engineering, and appears not to have implemented any of these recommendations.

The only mitigation for gas well risk that MWD’s engineers are proposing in the WaterFix Conceptual Engineering Report is to “identify the minimum allowable distance between wells and tunnel excavation” with a future study. The 2015 Conceptual Engineering Report also states that “it is anticipated that the State of California Division of Occupational Safety and Health (Cal/OSHA) may classify the tunnels as ‘potentially gassy.'”

North Delta Cares presented testimony in the WaterFix Water Right Change Petition Hearing by Mark Pruner, who is on the Board of Directors for the Clarksburg Fire Protection District.    Pruner testified on cross-examination that DWR had never discussed the gas well risk with the Clarksburg Fire Protection District, nor disclosed the recommendations of the 2010 Independent Review Committee on tunneling through a gas field.  Pruner testified that the Clarksburg Fire Protection District would have commented that DWR must follow the recommendations of the Independent Review Committee.

DWR’s attorneys objected to the entire line of questioning.

Metropolitan Water District has a disastrous history with tunneling through strata with methane gas. The worst tunneling accident in California history occurred in 1971 during MWD’s boring of the 22′ Sylmar tunnel to Castaic reservoir with a tunnel boring machine.    The Sylmar tunnel was known to go through strata with oil and gas.    As documented by in an engineering journal article by Richard J. Proctor, former Chief Geologist for MWD:

(1) The MWD geologic report, given with the Specifications to all bidders, warned of the possibility of encountering oil and/or gas in the western part of the tunnel route. This warning was based on: (a) producing oil fields in the region; (b) oil and tar seeps in the area; (c) the presence of Pico Formation sandstone in the western part of the tunnel route—a known source-rock of oil; (d) the presence of oil and gas in two nearby tunnels—the L.A. Department of Water and Power’s Newhall Tunnel in 1912, and the MWD’s Balboa Tunnel in 1967; (e) the crossing of the Santa Susana fault, which acts as an oil trap in the nearby Cascade Oil Field.

(2) Several months before the explosion, the contractor posted a notice that stated ”Expect explosive gas ahead.”

There were other factors listed in the article by Proctor.   Lockheed was the low bidder on the tunnel construction contract, and was trying to finish the tunnel quickly to get a bonus from Metropolitan Water District for early completion.  Workers on the tunnel were not adequately trained.  When workers smelled gas, the supervisor stopped work briefly, but then kept going, and did not implement all the recommended precautions.   The day of the fatal explosion, they had to stop work 35 times. Firefighters worked under extremely hazardous conditions in the smoky, water filled tunnel for the next two days, extinguishing fires and searching for workers.

After the fatal explosion, construction was halted for 2 years while MWD, Lockeheed, and OSHA figured out how to proceed safely.   Lockheed also filed a breach of contract suit against MWD for not warning of the real danger of encountering gas during tunnel boring.

1 The Sylmar Tunnel Disaster, June 23, 1971 Source: Los Angeles Firemen’s Relief Association

There was a 54-week criminal trial against the tunnel contractor, resulting in the highest municipal fines and some of the greatest civil damages awards of its time. After the longest municipal court trial in U.S. history, Lockheed Shipbuilding & Construction Co., a subsidiary of Lockheed Aircraft, was found guilty of gross negligence and violating state safety laws, and fined $106,250.  Lockheed was also forced to pay $9.3 million in civil judgments.

MWD dedicated a plaque to the 17 workers who were killed in the explosion in December of 2013.  But MWD appears not to have connected the dots with the need to follow the recommended precautions for tunneling through the Rio Vista gas field for the WaterFix project.

Corrected re: Rio Vista gas field 4/30.

Note:  As a result of efforts by California Water Research and coverage by the Sacramento News and Review, MWD has begun working on mapping gas wells in the Delta tunnel alignment.

One thought on “WaterFix tunnel construction: gas wells

  1. Thanks. The delay in disclosing the engineering study seems consistent with the lack of transparency on the Oroville Dam work

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