CANADIAN - U.S. WEST COAST SYSTEM SET FOR MAJOR EXPANSION

John A. Bianucci, Kristi Hein, Roland K. Young
Pacific Gas Transmission Co.
San Francisco

Expansion of a major Canada-to-California natural-gas pipeline will get under way this fall.

Pacific Gas Transmission Co.-Pacific Gas & Electric Co.'s 844 mile, 42 and 36 in. expansion of the existing PGT-PG&E system received conditional approval from the U.S. Federal Energy Regulatory Commission last month (OGJ, June 24, p. 29; Aug. 5, Newsletter). PGT is the interstate subsidiary of PG&E.

In December 1988, PGT filed an application with the FERC under Section 7(c) of the Natural Gas Act for approval to expand its facilities in Idaho, Washington, and Oregon.

Shortly thereafter, PG&E filed with the California Public Utilities Commission (CPUC) to expand its facilities in California.

This approximately $1.5 billion expansion project will transport more than 900 MMcfd of Canadian natural gas to serve growing markets in the Pacific Northwest and California. The CPUC estimates that the California market alone will need an additional 2.1 bcfd of natural gas by the year 2010.

The expansion project will install approximately 840 miles of 42 and 36-in. steel pipe, upgrading 4 major metering stations and 17 compressor stations and constructing a new compressor station.

Gas is scheduled to begin flowing on the expansion project in November 1993,

COMMITMENTS, ROUTING

Construction of the original natural-gas pipeline from Alberta to California began a transportation system that has served 10 million residential, commercial, and industrial customers since 1961.

In the spring of 1989, PGT and PG&E announced commitments from shippers for the full capacity of the expansion project.

When the FERC required a second open season earlier this year, the resulting requests for firm transportation were almost three times the project's designed capacity.

These results reaffirmed both the market demand for Canadian natural gas on the West Coast and the expansion project as the means to get it there.

(See list of shippers, OGJ, June 24, p. 29)

The expansion project's route crosses diverse terrain, including low-lying delta areas, upland rolling hills, steep mountain slopes, plateaus, and forest lands. Additional crossings will be necessary for some 40 railroads; 400 state, county, and local roads; and nearly 700 rivers, lakes, and streams.

From central Oregon to Red Bluff, Calif., where the route traverses about 200 miles of volcanic rock, explosives will be needed to blast out the pipeline trench. Construction methods must be adapted to the special demands of changing terrain along the way.

The current Alberta-to-California system consists of 911 miles of 36-in. pipe from Canada to the San Francisco Bay area. PG&E's Line 2 extends 120 miles from the Bay area to Panoche station in Fresno County. From there, PG&E's Line 300 extends to Kern River station in Kern County where it interconnects with the facilities of Southern California Gas Co.

The expansion project will loop PGT and PG&E's existing Alberta-to-California pipeline system (Fig. 1).

Portions of the original system were looped in the 1970s as part of the prebuild of the Alaska Natural Gas Transportation System (Angts). That system has yet to be built.

At that time, 161 miles of 42-in. pipeline were installed as part of Angts, and 39 additional miles of pipeline have been installed to increase system efficiency.

More than 95% of the expansion project parallels the existing pipeline within its 75100 ft wide right-of-way. Small alignment adjustments have been made to avoid environmentally sensitive areas.

CONTRACTS, SPREADS

On Feb. 26, 1990, Bechtel Corp. was hired to manage the engineering, procurement, construction, and testing of the expansion project.

On the engineering front, Gulf Interstate Engineering-Kaiser Engineers (Gulf) and Fish Engineering & Construction (Fish), both of Houston, have been selected by Bechtel to perform detailed engineering and design work.

Together, Gulf and Fish will produce more than 10,000 engineering drawings for the expansion project.

To secure the massive quantity of main line pipe needed, Bechtel awarded contracts to Napa Pipe Corp., Napa, Calif. (a wholly owned subsidiary of Oregon Steel), to manufacture 660 miles of longitudinally welded 42 and 36-in. pipe for the project and to Ipsco Inc., Regina, Sask., for 180 miles of spirally welded 42-in. pipe.

The steel pipe's combined weight of 400,000 tons ranks it among the world's largest single pipe orders at a cost of approximately $400 million. The pipe will be a combination of API Grades 5L X65 and X70, with wall thicknesses ranging from 0.409 in. (U.S. Department of Transportation Class I locations) up to 0.625 in. (DOT Class III locations).

The pipe will be externally coated with fusion-bonded epoxy and internally coated with epoxy paint. It will be shipped in 80-ft lengths from the steel mills and transported in an estimated 5,000 railroad carloads to 14 stockpile areas along the pipeline route.

Bechtel has also awarded more than $65 million in contracts to firms-Cooper Rolls Inc. and Solar Turbines Inc.-for turbines and compressors needed for the expansion project. Orders for other equipment requiring long lead times have also been placed.

Pipeline construction will be performed by contractors hired by Bechtel and managed from field offices in Bend, Ore. (for construction in Idaho, Washington, and Oregon), and Red Bluff, Calif. (for construction in California).

The project construction will be segregated into nine spreads ("A" spreads for 1992 construction; "B" spreads for 1993 construction) and will be let in five contracts.

Environmental and operational requirements have been incorporated into the design and timing for each spread in order to reduce construction-related impacts (Fig. 2).

This fall, construction will commence with the installation of 42-in. pipe by the directional-bore method under the Sacramento Delta area in California. More discussion on this activity is offered presently.

Bid packages for the remainder of project construction were released last month. Notice of successful bids will be announced before yearend with full construction slated to commence early next year.

The total value of the five pipeline-spread construction packages is to be about $400 million.

The 2-year construction period was planned to ensure the availability of those construction firms with the experience and equipment to install 42-in. pipe. At the height of construction activity, as many as 5,000 workers will be engaged in expansion project activities.

And the 2-year schedule allows PGT and PG&E to maintain gas throughput levels and keep providing current levels of service to existing customers.

PGT and PG&E have established quality-assurance (QA) requirements to be followed by the project team, Bechtel, major equipment and materials suppliers, and subcontractors engaged in design engineering and construction.

The overall project is regularly reviewed by an integrated QA team from PGT, PG&E, and Bechtel to ensure that management systems are in place, implemented, and effective.

COMPRESSOR STATIONS

Currently, PGT and PG&E operate 29 gas-turbine-driven compressor units ranging from 9,000 to 16,000 hp on the existing pipeline.

As part of the project, three 35,000-hp Cooper Rolls gas-turbine-driven compressor units will be installed on the PGT system, two of which - at Eastport (Station No. 3) and Athol, Ida.-will replace existing smaller units. The third unit, at Starbuck, Wash., will be an addition.

One new 14,000-hp Solar gas-turbine-driven compressor unit will be installed on the PG&E system at Delevan station near Willows, Calif. In addition, compressors on 18 existing units will be replaced with larger compressors.

One new compressor station is planned to be constructed at Bethany in northeast Alameda County near San Francisco, with two 7,000-hp, variable-speed electric motors driving centrifugal compressors.

Compressor-station construction will require approximately 6 months for completion at each location and will generally involve a station shutdown time of 2-4 months.

This work will be spread over 2 years to minimize interference with system operations.

On the PGT segment of the pipeline, recently developed fiber optic-based pressure and temperature transmitters for station process data will be installed. This technology will remove electro-magnetic field and radio frequency interference, ensuring greater accuracy and dependability of operating data.

Also, flow-measuring devices will be installed on both pipelines at each compressor station to improve pipeline inventory calculations. The four new gas turbines purchased for the expansion project will be outfitted with programmable logic controller control systems.

These turbines will be supplied with dry low-NOx combustors to reduce air emissions.

The 1994 installation of these combustors will be the first commercial pipeline application of this technology.

Solar Turbines will also retrofit this technology on two Solar units installed on the PGT system in 1990. Solar is currently working with PGT to install a prototype low-NOx combustor system on one of these units in 1992 for field testing.

Two PGT and two PG&E meter stations will be modified to accommodate expansion-project volumes.

PGT meter stations in Oregon will be modified, with installation of seven new 20-in. orifice meters at Malin (Fig. 2) and a fourth 12-in. turbine meter at Stanfield.

PG&E's Panoche meter station will be expanded with insertion flow meters for inventory control, and two new orifice meter runs will be added to the Kern River meter station.

DIRECTIONAL DRILLING

The portion of the route referred to as the Sacramento Delta crossings traverses three bodies of water that separate lower Sacramento and Solano counties from northeastern Contra Costa County (Fig. 4). The Sacramento Delta area supports important regional maritime, recreation, and fishery functions.

Crossing the Sacramento Delta involves the installation of 42-in. pipe in three segments totaling slightly more than 10,700 ft.

By directionally drilling the three crossings of the Sacramento Delta, the project will save time and virtually eliminate environmental and other disturbances associated with conventional open-cut trenching.

The Sacramento Delta crossings will be the first pipeline segments to be undertaken. Construction of the 2,680-ft Dutch Slough crossing and the 3,520-ft San Joaquin River crossing could begin in October and be completed in December and next February, respectively.

The final leg, the 4,550-ft Sacramento River crossing, will be built between November 1991 and April 1992.

This last and longest crossing, according to Bechtel, will be the longest bore for 42-in. pipe ever completed.

In July, Cherrington Corp., Sacramento, was selected by Bechtel to construct the three Sacramento Delta crossings. The directionally drilled river crossing consists of the following steps:

• The drilling and pulling platforms are prepared.

• A containment cell is constructed because the drill entry and exit points are below the adjacent water level.

• The pipe strings are laid out, welded, and hydrostatically tested before installation.

• The pilot hole is drilled and then reamed to the appropriate diameter.

• The pipe is installed by pulling it through the hole.

• Once in place, the pipeline is again hydrostatically tested.

Construction setback from the water's edge will typically be 700 ft to minimize the possibility of impact on adjacent wetlands. By the time the drill hole reaches the river's edge, its depth will be 5060 ft.

Once below the river, the pipe profile will be approximately 45 ft below the river bottom to reduce the risk of seepage into the drilled hole and damage to the pipe (Fig. 5).

The pipe used for the river crossing will be coated with thin-film, fusion-bonded epoxy (FBE) and wrapped in a coal-tar urethane overcoat to protect the FBE coating from damage during installation.

Pre-installation hydrostatic testing will occur over a period of 4 hr at the hydrostatic minimum and maximum pressures of 1,755 psig and 1,950 psig, respectively.

After installation, the second hydrostatic test will run for 8 hr at a minimum 1,560 psig and maximum 1,755 psig. Test water will be taken from the delta and returned following testing.

Directionally drilling the Sacramento Delta waterways risks the possibility of bore failure, causing flood conditions on one or both of the below-river-level islands.

While careful construction methods should prevent such an occurrence, additional protection will be afforded by the use of a drilling mud composed of bentonite, a naturally occurring, chemically and biologically inert clay.

This mud lubricates the drilling appliances during drilling, rearming, and pullback, and provides pressure to maintain the drilled hole. As them mud is forced through the hole, it also carries the drilled-out cuttings up to the surface and prevents water intrusion into the bore in the event of contact with the river.

Still another safeguard is provided by containment cells made of steel sheet pilings. These will be built on the islands to contain any water that could escape as a result of a bore failure. The cells w 11 be 60 x 400 ft, and the sheet pilings will be driven to depths of up to 75 ft.

The crossings have been designed by Gulf Interstate, with final joint configuration and detailed design by Bechtel, Gulf, and Cherrington.

ENVIRONMENTAL PROTECTION

Major pipeline projects often limit precertification environmental work to literature searches, with the project proponent awaiting direction from the FERC or other agencies to ascertain the extent of environmental field work and analysis required.

The PGT-PG&E pipeline expansion project incorporated environmental field work and analysis early in the design and construction planning.

Because 95% of the pipe line parallels an existing pipeline, the route was generally well established, and site-specific environmental surveys could be performed with more confidence in the final alignment location.

This,approach allowed for a thorough environmental review and early resolution of most environmental issues because much site-specific information was available to project and agency staff during the regulatory review process.

While the entire range of environmental factors along the route was examined, project staff and consultants conducted intensive field studies of cultural resources, threatened and endangered plant and animal species, and wetlands.

The National Environmental Policy Act and the California Environmental Quality Act provide the basis for the project's environmental activities. The FERC Environmental Impact Statement (EIS) and CPUC Environmental Impact Report (EIR) are both required by these acts and each runs to several volumes.

Among other significant statutory requirements with which the project must comply are the 1966 National Historic Preservation Act and the 1973 Endangered Species Act.

Numerous site-specific mitigation plans are in the process of being submitted to the FERC and CPUC and federal land-managing agencies.

One plan requires construction workers to receive ongoing instruction in environmental awareness and work practices; another plan addresses control of noxious weeds; another provides site-specific methods for revegetation; and so on.

Total environmental mitigation is currently estimated to cost at least $20 million.

Areas of particular environmental concern along the route (such as wetlands and archaeological sites) will require special care during construction.

Rivers and streams will be crossed during low flow, and specifically designed erosion control and revegetation measures will be employed.

Additional wildlife surveys will be conducted immediately before construction to determine whether rare and endangered species are present, so that appropriate mitigation can be undertaken. During construction, the project Will have its own environmental monitors in the field in addition to agency monitors.

The pipeline route crosses the winding course of Idaho's Moyie River eight times. Implementation of a special fishery-enhancement program developed for the Moyie River is expected to result in an improvement over preproject fishery conditions on the Moyie.

Placement of rock structures in the river will create a more irregular channel bottom, thus improving trout habitat.

The plan has been approved by the Idaho Department of Fish and Game, the Department of Water Resources, the U.S. Army Corps of Engineers, various sports clubs, and local property owners. PGT will monitor the success of this plan following completion of the project.

Copyright 1991 Oil & Gas Journal. All Rights Reserved.