Rod M. Gann, Barbara Beverlin
Arkla Energy Resources
Shreveport, La.
Arkla Energy Resources (AER), a division of Arkla Inc., Shreveport, La., recently completed construction of a 221-mile, 42 and 36-in. natural-gas pipeline.
Known as Line AC, it allows gas delivery from the rich Arkoma basin of Oklahoma to eastern and midwestern U.S. markets. Partners in the line, in addition to Arkla, are ANR Pipeline Co., Texas Gas Transmission, Tennessee Gas Pipeline, and Columbia Gulf.
The pipeline runs from Arkla's Chandler compressor station west of Wilburton, Okla., southeast to Mississippi River Transmission's (MRT) Glendale compression station south of Pine Bluff, Ark. (Fig. 1).
Construction of Line AC surmounted significant environmental and engineering obstacles to begin flowing gas Nov. 1, 1990.
ARKOMA ACTIVITY
The concept of Line AC can be traced back to 1986 when Atlantic Richfield Co. (ARCO) discovered a new producing zone near Wilburton.
In early 1989, Arkla made the strategic decision to expand its west-to-east pipeline system out of the Arkoma basin. The primary reasons for this decision were the following:
- Significant new discoveries were being made adjacent to the Arkla system.
- New markets were accessible for producers.
- Requests were received for additional firm transportation service.
- There was a lack of additional firm west-to-east capacity.
Arkla decided to install the 221-mile pipeline under Section 311 of the Natural Gas Policy Act (1978). The decision was very difficult in many respects.
The nation at the time had an overall excess of deliverability. Prices were low, and very few major lines were being projected anywhere in the country.
Design work, right-of-way (ROW) acquisition, and environmental considerations presented many timing and coordination problems.
In order to meet the specific deadlines that were established, Arkla contracted Willbros Butler Engineering Inc. (WBEI), Tulsa, to provide engineering, ROW acquisition, and construction inspection.
Personnel from Arkla's environmental department worked with federal and state agencies to see that all existing requirements were met. (See accompanying box.)
Four types of endangered animal species were known to be in the regions where the pipeline was to be installed. These included the Red Cockaded Woodpecker, the American Burying Beetle, the Ouachita Rock Pocket-Book Mussel, and the Leopard Darter.
Each was dealt with in accordance with procedures dictated by the U.S. Fish and Wildlife Service.
The presence of the endangered species in the woodlands, rivers, and streams caused Arkla to reroute the line several times after the initial pipeline route was planned.
Significant rivers and creeks which contain the Leopard Darter and the Ouachita Rock Pocket-Book Mussel include the Kiamichi, Mountain Fork, Big Eagle Creek, Honobia Creek, and Little River in Oklahoma, and the Ouachita, Caddo, and Little Missouri rivers in Arkansas.
Arkla environmental employees worked with state personnel to identify approximately 97 possible archaeological sites along the right-of-way, resulting in 13 reroutes in Arkansas and 3 in Oklahoma.
Special consideration was given to two of the planned river crossings because of their classification as wild and scenic: the Mountain Fork River in Oklahoma and Cossatot River in Arkansas. Both of these crossings will be discussed later.
EASTERN SEGMENT
Construction was scheduled for June through October 1989 for the first 59 miles of 36-in. pipeline, which connected Arkla's Line S-3-S near Malvern, Ark., to the MRT system at Glendale.
Contracts were awarded to Michael Curran & Associates and to Associated Pipeline, both of Houston, to construct the two spreads. This segment of work progressed smoothly with minimum problems.
Associated additionally was awarded the Glendale station measurement facility.
Spread 1 had 6 highway crossings and 18 secondary road crossings. One standard launcher was installed at the junction of the new line and Arkla's Line S-3-S south of Malvern. The spread also included one main line valve setting.
All of Spread 1 was hydrostatically tested at one time. The high elevation was tested at 95.1 % of specified minimum yield strength (SMYS) and the low elevation at 104% of SMYS.
Spread 2 had seven highways, one railroad, one major river, and ten secondary roads to cross.
The hydrostatic testing on this spread was accomplished in two sections because of the pipe wall-thickness change in a Class 2 location. Test pressures varied from 101.8% of SMYS at the low elevation point to 98.2% at the high point.
The meter facility consisted of a 350-MMcfd filter separator, two 12-in. tubes, two 12 x 8-in. reducing regulators, and one 36-in. receiver. Each of the meter and regulator headers was designed to be expandable to six tubes and regulators.
Initial gas deliveries began Nov. 30, 1989, from Arkla's Line S-3-S to MRT's Glendale station at a flow of 250 MMcfd.
Pipe procurement on short notice was a problem. The only supplier that could deliver the required amount of 36-in. pipe in the necessary time frame was GTS Industries, Houston, which has mills in France.
Arkla's first order was for 36-in. 5L X65 pipe in three different wall thicknesses: 0.391 in. for Class 1 locations, 0.469 in. for Class 2 locations, and 0.562 in. for Class 3 locations.
Pipe was shipped from Dunkirk, France, to Houston for unloading and inspection for shipment damage. The pipe was then conveyed by truck to Lone Star, Tex., where it was double-jointed into 80-ft lengths by Curran & Associates and coated at A & A Coaters with an 18-mil minimum thickness 3M thin-film epoxy coating.
THREE SPREADS FROM WEST
After the first 59 miles were completed, WBEI was again retained in the same capacity for the remaining 162 miles of pipeline. The 1990 portion of the work called for completion by Nov. 1.
Additionally, while the 36-in. segment was being constructed, marketing requirements dictated an increase in capacity of the pipeline to 1.05 bcfd resulting in a change in diameter of the first 145 miles from 36 in. to 42 in.
Construction was planned for three spreads along with separate contracts for the construction of a 1 bcfd measurement facility at Chandler station, a suspension bridge, and a girder bridge.
Contracts were awarded to Michael Curran & Associates of Houston for Spreads 1 and 3 along with the Cossatot area line and bridge; Delta Gulf of Shreveport for Spread 2; and Staid Pipeline Construction, Morrilton, Ark., for the Chandler measurement facility and Glendale measurement expansion.
All pipe was API 5L X65 grade and was purchased from three different vendors in three different countries:
- 26.1 miles of 0.469-in. W.T. pipe were manufactured by Ilva in Taranto, Italy.
- 60.1 miles of 0.469-in. W.T. as Well as 10 joints of 0.750-in. W.T. for hot bends were manufactured by Berg Steel Pipe Corp., Panama City, Fla.
- The remaining 59.6 miles, consisting of 0.469-in. W.T., 0.562-in. W.T., and 0.688-in. W.T., were manufactured by GTS Industries in Dunkirk, France. The additional 17 miles of 36-in. pipe were manufactured by GTS.
Pipe manufactured in Florida was transported to Lone Star for double-jointing and fusion-bonded epoxy (FBE) coating application.
All pipe coming from foreign mills was transported by ship to the Port of Houston for unloading and inspection with further shipment to Lone Star for the double-jointing and coating application.
Only the 0.469-in. W.T. 42-in. pipe and the 0.391-in. W.T. 36-in. pipe were doublejointed. More than 3,900 truck loads were required to haul the pipe from Panama City and Houston to Lone Star (Fig. 2).
A special polymer-cement coating was applied at a thickness of 125 mils to the epoxy coating and was used for all road crossings to prevent damage to the existing coating. The coating proved to be extremely tough and provided adequate protection under bored roadways in rocky areas.
After the final operation was completed in Lone Star, the pipe was hauled again by truck to various storage yards in Arkansas and Oklahoma to await stringing by the installation contractors.
The three main spreads were divided into lengths that would allow each spread to be completed at the same time. This resulted in the lengths being 41.9 miles, 57.5 miles, and 62.6 miles for Spreads 1, 2, and 3, respectively.
Except for the extensive presence of rock throughout the route and the mountainous terrain of southeastern Oklahoma, the right-of-way was typical rolling hill countryside.
The large amount of rock resulted in the extensive use of sand bags to support and protect the pipe. More than 800,000 sand bags were laid on the trench bottom at intervals of 10 ft.
A combination of rock shield and padding was used to protect the pipe and coating during backfill operations.
Field joints were coated with FBE. A 7.5-in. thickness of reinforced concrete coating was field applied to 0.688-in. W.T. pipe for stream and river crossings.
The mountainous area of Spread 1 required 12 hydrostatic tests in the 41.9 miles. Pipe was hydrostatically tested to a minimum of 90% SMYS.
The pipeline crossed 7 U.S. highways, 12 state highways, 9 paved county roads, 72 secondary roads, and 4 railroads. In addition, the line crossed 6 rivers and 34 streams.
All the main line valves were Cameron full-port ball valves equipped with Shafer operators. Two 42-in. launchers and two 42-in. receivers along with two 36-in. launcher/receiver combinations were installed.
Incoming gas to the pipeline is measured through the Chandler measurement facility. It consists of three separate measurement/regulator combinations.
The first and main meter run has eight 12-in. orifice meters and four 12 x 8-in. regulators.
The second meter run has five 12-in. orifice meters and three regulators.
The final meter station consists of three 12-in. orifice meters and two regulators.
Valve and manifold configuration allows Arkla to select several combinations to route gas flow as required. The installation also utilizes a self-contained electronic measurement and telemetry building.
To determine any physical deformities, caliper pigs were run by Enduro after hydrostatic testing.
CROSSINGS, BRIDGES
The crossing of the Kiamichi River in southeastern Oklahoma runs parallel to a new highway bridge that was under construction just south of Talihina in Pushmataha County.
To meet environmental requirements, Arkla was allowed to proceed with a conventional submerged crossing as long as the installation coincided with the bridge construction.
Willbros Energy of Tulsa was contracted to make the crossing consisting of 1,380 ft of 42-in. X65 0.688-in. W.T. pipe. Construction began in February 1990.
Several heavy rains caused delays on both the pipeline and the bridge. As a result, completion was not until May 1990.
After considerable study, it was concluded that the most economical method of crossing the Mountain Fork River and meeting environmental requirements was by suspension bridge.
The bridge, spanning 775 ft, was designed by Clear Span of Houston. It consists of two 88-ft tall inverted "Y" towers, four main cables, 2 3/8-in. O.D. each, anchored to a 350 cu yd anchor block, with 31 sets of suspender cables at 25-ft spacing to which the pipe cradles were attached (Fig. 3).
Tower segments were fabricated in Houston and assembled at the job site. A portable concrete plant was utilized at the construction site for concrete placement.
After the towers were fabricated and erected and the cable assemblies attached, the 42-in., 0.688-in. W.T. pipe was pulled across (Fig. 4). Each saddle that was supported by suspender cables had to have a temporary roller assembly attached so the pipe could be pushed across the bridge.
The direction of travel was from the high bank toward the lower one, some 80-ft change in elevation.
Pullback clamps were installed on the pipe so that a restraining cable could help hold the pipe from free sliding due to gravity. After the pipeline was across the bridge and tied in to the main line segments, steel armor plate was placed under and on both sides of the exposed pipe to protect it.
COSSATOT RIVER, STATE PARK
About a mile of the pipeline crosses through an environmentally sensitive location called the Cossatot Natural Area.
The most economical way to cross the Cossatot River in the middle of the natural area was by bridge.
A girder bridge, 395 ft long, was fabricated by Capitol Steel, Oklahoma City, to cross the Cossatot River. It was transported to the site in four segments for placement onto the abutments and piers, with the four segments being bolted and welded together (Fig. 5).
Pipe was pushed through the bridge with a trolly system built into the bridge itself.
Cradles that supported the pipe for pushing onto the bridge were reversed and used as clamps when the pipe was lowered to its final position.
Railing was installed on the bridge allowing the bridge to be utilized as a pedestrian crossover for the park. The entire park segment utilized 0.688-in. W.T. pipe.
Arkla is currently constructing park facilities near the bridge. When finished, this park will become the "Cossatot State Park and Natural Area."
All welders on Line AC construction were qualified under API 1104. Contractors used Lincoln 5P + rod for the root bead. The hot pass was completed with Lincoln 8010 rods.
This 8010 (70+) was also used to finish and bead out each weld.
Line AC was placed into service on Nov. 1, 1990, with a capacity of 800 MMcfd without compression.
Arkla is currently constructing a 14,750-hp reciprocating compressor station near Malvern that will boost delivery to 1 bcfd by late this summer.
Capacity share ownerships in the line are: ANR Pipeline Co. 250 MMcfd, Texas Gas Transmission 300 MMcfd, and Tennessee Gas Pipeline and Columbia Gulf, each 85 MMcfd.
This distribution leaves Arkla with a capacity of 280 MMcfd after completion of compression.
Copyright 1991 Oil & Gas Journal. All Rights Reserved.
