View source for Path 66

{{Short description|Corridor of three roughly parallel power lines}}
[[File:Pacific intertie geographic map.png|thumb|right|Pacific Intertie transmission routes]]
[[File:Dual Circuit 500kV power lines crossing I580.JPG|thumb|A dual-circuit 500 kV line forming a part of the connection between Path 66 and [[Path 15]].]]
'''California Oregon Intertie''' ('''COI'''), identified as '''Path 66''' by [[Western Electricity Coordinating Council]] (WECC), is a corridor of three roughly parallel 500 [[volt|kV]] [[alternating current]] [[electric power transmission|power lines]] connecting the electric grids of [[Oregon]] and [[California]]. Their combined power transmission capacity is 4800 [[watt|MW]].<ref name="UTIL">{{Cite web|title=COI Utilization Report|publisher=Transmission Utilization Group|date=2011-05-04|url=http://www.wecc.biz/committees/BOD/TEPPC/05241102/Lists/Minutes/1/COI%20Utilization%20Report.pdf|accessdate=2014-03-30|archive-url=https://web.archive.org/web/20140407080925/http://www.wecc.biz/committees/BOD/TEPPC/05241102/Lists/Minutes/1/COI%20Utilization%20Report.pdf|archive-date=2014-04-07|url-status=dead}}</ref>

Two of the power lines run from [[Malin, Oregon|Malin]] Substation ({{coord|42|0|20.7|N|121|18|59.7|W|display=inline}}) southeast of [[Klamath Falls, Oregon]] to [[Round Mountain, California|Round Mountain]] Substation northeast of [[Redding, California]]. One of them is owned by [[Western Area Power Administration]], with the other owned by [[Pacific Gas and Electric]] and [[PacifiCorp]] jointly.<ref name="UTIL"/> These lines are a part of [[Pacific Intertie|Pacific AC Intertie]] and were completed in the 1960s. The third line runs from [[Kintpuash|Captain Jack]] Substation near Malin to Olinda Substation south of Redding. It is a part of California-Oregon Transmission Project. The project manager is the Transmission Agency of Northern California (TANC), a joint venture of several public utilities. The line was completed in 1993.
<ref name="COTP">{{Cite web|title=California-Oregon Transmission Project|publisher=Transmission Agency of Northern California|url=http://www.tanc.us/cotp.html|accessdate=2014-03-31}}</ref>

==Route==
Path 66 is composed of one segment of TANC, PG&E and PacifiCorp 500 kV lines. The TANC line route starts at Captain Jack Substation ({{coord|42|04|47.1|N|121|23|24.0|W|display=inline}}) north of Malin and {{convert|6.5|mi|abbr=on}} northwest of the Malin Substation, where the other 500 kV lines start (owned by PacifiCorp and PG&E). These substations, just north of the California-Oregon border, link to both the [[PacifiCorp]] and [[Bonneville Power Administration]] (BPA) [[power grid|grid]]s in the [[Pacific Northwest]].<ref name="GEImage">Route descriptions and tower designs are based on Google Earth images.</ref><ref name="WECC">{{Cite report|title=Paths 61-70|publisher=Western Electricity Coordinating Council|year=2006|postscript=<!--None-->}}</ref><ref name="CAmap">{{Cite web|title=California Transmission Lines|url=http://www.energy.ca.gov/maps/TRANSMISSION_LINES.PDF|accessdate=2007-09-20}}</ref>

;Path 66 - Captain Jack to Olinda
Path 66 consists of the northernmost segment of TANC's {{Convert|346|mi|km|0|abbr=on}} 500 kV line from Captain Jack substation to Tracy substation in California's [[Central Valley (California)|Central Valley]]. Leaving Captain Jack 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 (California)|Grizzly Peak]] at about {{convert|6000|ft|m|-1|abbr=on}}.<ref name="GE">[[Google Earth]] elevation for [[Geographic Names Information System|GNIS]] coordinates.</ref> From there, it heads south, spanning over the [[Stonecoal Valley]] and the [[Pit River]]. Near [[Round Mountain, California|Round Mountain]], it turns southwest and the line is joined by two 230-kV lines as all three lines head into the [[Sacramento Valley]]. As the line passes by [[Cottonwood, California|Cottonwood]], it turns west and crosses [[Interstate 5 in California|Interstate 5]]. Near Olinda, it turns south and enters Olinda substation. Here the line interconnects with transmission lines carrying power from [[Shasta Dam]] and [[Keswick Dam]].<ref name="GEImage"/>

;Connecting wires to [[Path 15]] - Olinda to Tracy
From Olinda Substation, the TANC 500 kV continues as a [[Single-circuit transmission line|single-circuit]] line, although the tower structures change (see photos below) to a two-level [[Electricity pylon|pylon]]. The line proceeds south and then southeast along the western edge of the Sacramento Valley. It parallels [[Interstate 5 (California)|Interstate 5]] (about four miles (6.5&nbsp;km) to the west) on its way south, although it is barely visible. It also parallels two 230-kV [[Pacific Gas and Electric Company|Pacific Gas and Electric]] lines for much of this segment and another WAPA 230 kV line. There is a [[series capacitor]] station near [[Maxwell, California|Maxwell]] in [[Colusa County]] to boost the line across the long Olinda-Tracy segment.<ref name="GEImage"/>

The line crosses the two separated PG&E 500-kV lines, near [[Woodland, California|Woodland]] and [[Rio Vista, California|Rio Vista]]. Near [[Antioch, California|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 TANC line turns away from the PG&E lines and heads for another large substation near Tracy.<ref name="GEImage"/>

;Connecting wires to Path 15 - Tracy to intersection with PG&E wire
From Tracy Substation, the line again to a rare, tall, [[Double-circuit transmission line|double-circuit]] 500 kV line suspended by a three-level pylon located in the [[San Joaquin Valley]]. The line terminates where it intersects with one of the two PG&E 500 kV lines as the PG&E heads [[south]] from the Tesla [[Electrical substation|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, although the foundation for the tower is still visible. New towers were built to accompany the line changes. 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 the Los Banos Substation as a southern extension of the third 500 kV line.<ref name="GEImage"/>

;Path 66 - Malin to Round Mountain
The other two 500 kV lines start in the [[Malin, Oregon|Malin]] substation southeast of the Captain Jack substation. One circuit of a rare,{{cn|date=May 2023}} 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),<ref name="GE"/> before descending and turning south once again. Both lines enter the [[Round Mountain, California|Round Mountain]] substation. This is the terminus of the Path 66 portion of the parallel 500 kV wires.<ref name="GEImage"/>

===Substations===
;Path 66
TANC line (North to South)
*Captain Jack
*Olinda
PG&E and PacifiCorp
*Malin
*Round Mountain
;Connecting power line
*Series capacitor station in [[Colusa County, California|Colusa County]]
*Tracy

==Issues==
;Power transmission capacity
Path 66 can transmit 4,800 [[watt|MW]] of [[electric power|electrical power]] from north to south. From south to  north, the system can transmit only 3,675 MW of power.<ref name="WECC"/>

;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.<ref name="GEImage"/> The land through here has been logged and sometimes clear-cut to create a right-of-way for the power lines because a wildfire could start when an electrical arc occurs between the wires and a tree if they come close enough to each other.<ref>{{Cite web|title=Trees and Power Lines|url=http://www.wapa.gov/newsroom/pdf/treesandpowerlines.pdf|publisher=Western Area Power Administration|accessdate=2007-09-20}}</ref>

==Tower design and differences==
This TANC 500 kV power line, unlike its PG&E counterparts, is triple-bundled, meaning that it has three wires per [[Polyphase system|phase]], whereas the PG&E lines are only double-bundled, or two wires per phase. In addition, the tower's design is strikingly different from the lighter and wider PG&E tower, and the design also changes significantly as one goes from north to south on WAPA's {{Convert|346|mi|km|0|abbr=on}} 500 kV line.<ref name="GEImage"/>

The TANC line changes design at the Olinda substation from the delta pylon pictured at the Interstate 5 crossing<ref>{{Cite web|title=Picture of TANC's 500 kV line from Interstate 5|url=http://www.westcoastroads.com/california/images005/i-005_nb_exit_667_03.jpg|publisher=WestCoastRoads.com|accessdate=2007-09-20|archive-url=https://web.archive.org/web/20070927020519/http://www.westcoastroads.com/california/images005/i-005_nb_exit_667_03.jpg|archive-date=2007-09-27|url-status=dead}}</ref><ref>{{Cite web|title=Picture of WAPA's 500 kV line from Interstate 5|url=http://www.westcoastroads.com/california/images005/i-005_sb_exit_665_01.jpg|publisher=WestCoastRoads.com|accessdate=2007-09-20|archive-url=https://web.archive.org/web/20070927020256/http://www.westcoastroads.com/california/images005/i-005_sb_exit_665_01.jpg|archive-date=2007-09-27|url-status=dead}}</ref> 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.<ref name="GEImage"/><ref name="CCN">{{Cite web|title=SN foreman outlines 3 decades of t-line ops|url=http://www.wapa.gov/newsroom/cct/2007/june18/29no122.htm|publisher=Western Area Power Administration|accessdate=2007-09-20 |archiveurl = https://web.archive.org/web/20070927200225/http://www.wapa.gov/newsroom/cct/2007/june18/29no122.htm <!-- Bot retrieved archive --> |archivedate = 2007-09-27}}</ref> The segment of TANC's 500 kV line 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.<ref name="GEImage"/> 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 [[California State Route 4|Highway 4]] and the western part of the [[San Joaquin River]] portion of the [[Sacramento–San Joaquin River Delta|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 that serves the pumping stations on the [[Contra Costa Canal]].<ref name="GEImage"/>

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 PG&E Table Mountain-Round Mountain 500 kV segment does. The PacifiCorp 500 kV line uses a pylon that looks similar to the pylon used in WAPA's Olinda-Captain Jack segment.<ref name="GEImage"/>

;Visual reference
<gallery>
File:DSCN2133_WAPA_500kV.JPG|WAPA Olinda-Tracy 500 kV transmission line outside of [[Vacaville, California|Vacaville]], near [[Interstate 80 (California)|Interstate 80]].
File:Pacific Gas and Electric 500 kV power lines.JPG|PG&E wires near Tracy.
File:PG&E wire spanning over WAPA line.JPG|PG&E 500 kV Table Mountain-Vaca Dixon line spanning over the WAPA line (Olinda-Tracy segment).
</gallery>

==Problems==
Since TANC's Captain Jack-Olinda 500 kV wire rises to almost {{Convert|6000|ft|m|-2}} as the line crosses the rugged mountains near Grizzly Peak,<ref name="GE"/> that section of 500 kV line is covered with large amounts of snow during the winter. Despite its location far from the [[Pacific Ocean]], {{Convert|20|ft|m|0}} of snow can accumulate near Grizzly Peak's {{Convert|6250|ft|m|0}}-summit.<ref name="CCN"/> The extreme snowfall there can cause ice and snow to accumulate on the insulators and the wires and sometimes lead to power outages when the wires snap in these extreme conditions.<ref name="CCN2">{{Cite web|title=Calif. snow gets SN crew out to repair line|url=http://www.wapa.gov/newsroom/cct/2007/mar26/29no61.htm|archive-url=https://archive.today/20121214085312/http://www.wapa.gov/newsroom/cct/2007/mar26/29no61.htm|url-status=dead|archive-date=2012-12-14|publisher=Western Area Power Administration|accessdate=2007-09-20}} </ref> This high-elevation segment of 500 kV line is also said to be problematic.<ref name="CCN"/>

==Map==
<gallery>
File:Path_15_2.GIF|Map of Path 66 located in the upper section, left of the other two 500 kV lines south of Round Mountain substation
</gallery>

==See also==
*[[Path 26]]

==References==
{{reflist|2}}

==External links==
*[https://web.archive.org/web/20070319185057/http://www.wapa.gov/newsroom/cct/2003/june20/25no134.htm WAPA.gov]
{{Power Transmission Corridors of the Western United States}}

[[Category:Western Interconnection]]
[[Category:Energy infrastructure in California]]
[[Category:PacifiCorp]]