Path 66
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Path 66 (also called the California Oregon Intertie or abbreviated COI) is the name of several 500 kV power lines that was built by Western Area Power Administration (WAPA), Pacific Gas & Electric (PG&E), and PacifiCorp in the early 1970s to 1990s and totally completed (energized) in 1993. It is the northern half of a set of three 500 kV lines that makes up the Pacific AC Intertie which is the AC portion of a greater project linking power grids in the Southwest with the grids in the Pacific Northwest (for more info see Path 15 and for the HVDC portion of the project, see Pacific DC Intertie). Also, this is the larger and older of the two segments of the Pacific AC Intertie that WAPA worked on, the other is the Los Banos-Gates third 500 kV wire of Path 15. The 350-mile (567 km) WAPA power line is in the California Central Valley, moreover the Sacramento Valley, for most of the time. Path 66 also includes also the Round Mountain-Malin segment of both parallel PG&E and PacifiCorp lines, which are located mostly in the Modoc Plateau.
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[edit] The route
Path 66 is composed of three segments of one WAPA 500 kV line and one segment of both PG&E and PacifiCorp line. The WAPA line route technically starts at Captain Jack Substation (named after Captain Jack) close to Malin, close to the California-Oregon border, near the Malin Substation, where the other 500 kV lines start (PacifiCorp & PG&E). These substations link to both the Pacificorp and Bonneville Power Administration (BPA) grid in the Pacific Northwest.
[edit] Western Area Power Adminstrations 500 kV wire (Captain Jack to Tracy substation)
The line first heads southeast as a single-circuit line and runs parallel with the other two 500 kV lines across the Modoc Plateau. It then turns west and climbs in elevation and reaches its highest point near Grizzly Peak at about 6,000 ft. (1,828 m). From there, it heads south, spanning over the Stonecoal Valley and the Pit River. Near Round Mountain, it turns southwest and is joined by two 230-kV lines. Near Cottonwood the line turns west and crosses Interstate 5. Near Olinda, it turns south and enters a substation. Here the line interconnects with transmission lines carrying power from Shasta Dam and Keswick Dam. From Olinda Substation, it continues as a single-circuit line, although the tower structures change (see photos below). The line proceeds south and then southeast along the western edge of the Sacramento Valley. It parallels Interstate 5 (about four miles (6.5 km) to the west) on its way south, although it's barely visible. It also parallels two 230-kV Pacific Gas & Electric lines for much of this segment and another WAPA 230 kV line. There is a substation near Maxwell in Colusa County to boost the line across the long Olinda-Tracy segment.
The line crosses the two PG&E 500-kV lines, near Woodland and Rio Vista. Near Antioch the line turns and runs parallel with the two PG&E 500 kV lines. All three lines cross both the Sacramento and San Joaquin Rivers on very large pylons. The WAPA line turns away from the PG&E lines and heads for another large substation near Tracy. From Tracy Substation, the line changes again to a rare, tall, dual-circuit 500 kV line. The line terminates where it intersects with one of the two PG&E 500 kV lines as it heads south from the Tesla substation towards Los Banos Substation. The PG&E line that the dual-circuit line intersects used to be a second Los Banos-Tesla power line that was split apart. A PG&E tower was removed (tower footing holes can still be seen) and new towers were built. One circuit turns north back into Tesla Substation, effectively linking the Tracy Substation with the Tesla Substation. The other circuit turns south to head for Los Banos Substation as a southern extension of the third 500 kV line.
[edit] Pacifc Gas & Electric and PacifiCorp line (Malin to Round Mountain)
The other two 500 kV lines start in the Malin substation to the east of the Captain Jack substation. One circuit of a rare, tall BPA dual-circuit and one single-circuit 500 kV line connect Captain Jack substation with Malin substation. The PG&E and PacifiCorp 500 kV line both head south together across the Modoc Plateau, generally following the lone WAPA line at a distance. The parallel lines then turn southwestward climb to about 5,400 feet (1,645 m), before descending and turning south once again. Both lines enter the Round Mountain substation. This is the terminus of the Path 66 portion of the parallel 500 kV wires; the portion south of Round Mountain is considered to be Path 15, unlike the lone WAPA line of Path 66, which continues down to Tracy.
[edit] Substations
WAPA line (North to South)
- Captain Jack
- Olinda
- Small, unnamed substation in Colusa County
- Tracy
PG&E and PacifiCorp
- Malin
- Round Mountain
[edit] Other information
[edit] Environmental impacts
The northern part of this electrical transmission corridor (including Path 15) is visible from space and Google Earth as lines of bare, treeless ground. This is because the power lines here run through forests of conifer trees which appear dark green-green from space. The land through here has been logged and sometimes clear-cut to create a right-of-way for the power lines due to the fact that a wildfire could start when an electrical arc and/or discharge occurs between the wires and a tree if they come close enough to each other.
[edit] Visual impacts
[edit] Tower design and differences
This WAPA 500 kV power line, unlike its PG&E counterparts, is triple-bundled, mean that it has three-wires per phase, whereas the PG&E lines is only double-bundled, or two wires per phase. In addition, the tower's design is strikingly different from the lighter, wider, but structurally thinner PG&E wires and the design also changes significantly as one goes from north to south on Path 66. For a comparison, see below:
Also, compare the above WAPA 500 kV wire picture with this photo of the Captain Jack-Olinda segment where it crosses Interstate 5 (located visually in between the two 230 kV tower in the foreground) and from a different angle (large, steel lattice tower in the background). The WAPA line changes design at the Olinda substation from the delta pylon pictured at the Interstate 5 crossing to the two-level pylon pictured above. This is because much of the segment between the Olinda and Tracy substations was constructed by upgrading an existing double-circuit 230 kV line. The segment of Path 66 from the Sacramento River crossing south to the Tracy Substation has delta pylons like those found on the Captain Jack-Olinda segment, although they are slightly different. This is because south of the Sacramento River crossing, the original 230 kV line paralleled the two PG&E 500 kV lines almost all the way to Tracy Substation. In order to meet separation requirements, a new alignment for the 500 kV line had to be built some distance to the east, with the exception of the San Joaquin River crossing, which utilizes the former 230 kV facilities. This alignment can be seen from Highway 4 and the western part of the San Joaquin River portion of the Sacramento River Delta. A portion of the former 230-kV line south of the Sacramento River remains in service today as part of the 69 kV system for eastern Contra Costa County.
As for the pylons of the PG&E and PacifiCorp Round Mountain-Malin parallel lines, the PG&E line uses the same tower type as the Path 15 Table Mountain-Round Mountain segment does. The PacifiCorp 500 kV line uses a pylon that looks similar to the pylon used in WAPA's Olinda-Captain Jack segment.
[edit] Maps
[edit] See also
[edit] External links
- WAPA.gov
- Transmission line map - Also includes problems with the transmission paths.
- Wecc.biz - Description of Paths 61-70.
- Route descriptions are based on Google Earth images.
Electric power transmission corridors of the Western United States |
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Path 15 • Path 21 • Path 26 • Path 45 • Path 46 • Path 61 • Path 62 • Path 63 • Path 64 • Path 66 |