Southern California Edison (SCE) Proposed Transmission Line Rating Remediation (TLRR) Program
Eagle Mountain-Blythe 161kV Subtransmission Line Project
TD684647
Located on Lands Administered by the Bureau of Land Management, Palm Springs Field Office
The Transmission Line Rating Remediation (TLRR) program is a compliance-based effort addressing 300 circuits throughout Southern California Edison’s (SCE) service territory with 11,164 discrepancies with a revised California Public Utilities Commission (CPUC) General Order (G.O.) 95. A discrepancy is generally a clearance problem between an energized conductor and its surroundings, such as the structure, another energized conductor of the same line or a different line, or the ground. If sufficient clearance is not available, the circuit can short out, which reduces reliability.
SCE’s Eagle Mountain - Blythe (EM-B) TLRR Project (Project) will be performed to eliminate approximately 164 phase to ground clearance discrepancies. The Circuit extends approximately 53 miles from the Eagle Mountain Substation near Desert Center, California, to the Blythe Substation in Blythe, California. To clear the discrepancies, the Project scope consists of removing 24 Pumco steel poles and installing 16 tubular steel poles (TSPs), replacing 19 wood three-pole dead-end structures with 19 three-pole TSPs, replacing 30 wood H-frame structures with 30 Light Weight Steel (LSW) H-frame structures, and replacing one single wood pole with a single TSP. The existing 161-kV Circuit, consisting of both 336 Linnet and 336 Merlin aluminum conductor steel-reinforced (ACSR) line, will be replaced with 336 Oriole ACSR conductors.
The EM-B TLRR Project is located entirely within the Chuckwalla Valley in Riverside County, California. The circuit extends approximately 53 miles (approximately 279,840 feet) and encompasses 581 acres from the Eagle Mountain Substation near Desert Center, California to the Blythe Substation in Blythe, California. The Project falls within the Victory Pass, East of Victory Pass, Corn Spring, Sidewinder Well, Aztec Mines, East of Aztec Mines, Hopkins Well, Roosevelt Mine, and Ripley 7.5-minute U.S. Geological Survey (USGS) topographic quadrangles.
The Project is located on a combination of BLM-administered lands, incorporated and unincorporated portions of Eastern Riverside County, and private land. The portion of the Project located on BLM-administered land includes approximately 34 miles and 397 acres, which are subject to right-of-way (ROW) Grant CALA-0149780. There is also a 7-mile overlap with the existing Devers-Palo Verde 2 (DVP2) ROW. Project components on BLM-administered land include existing poles proposed for access only, guard sites, structure work areas, and wire setup areas. Project components located on private land include existing poles proposed for access only, material yards, guard sites, structure work areas, and wire setup areas.
The purpose of this project is to increase the phase-to-ground or phase-to-phase clearance for the EM-B line. The Project is needed to comply with the North American Electric Reliability Corporation (NERC) and Western Electricity Coordinating Council (WECC) standards, and the revised CPUC G.O. 95. SCE requires that all circuits meet or exceed the most stringent strength, clearance, and reliability requirements of those regulating bodies. GO 95, while not applicable to the NERC transmission ratings requirements, requires greater mechanical and electrical performance. SCE has determined that all of its lines will meet the requirements of GO 95 and that any remediation efforts requiring new construction will meet the latest SCE standards. Without the Project, sufficient clearance for the line(s) is not available, and the circuit has the potential to short out, reducing reliability, and increasing public health and safety hazards.
The EM-B line includes an existing 161-kV circuit and the associated alignment, with 66-kV and 12-kV underbuild circuits on portions of the alignment. The EM-B TLRR project will replace the existing 161-kV circuit 336 Linnet and 336 Merlin ACSR conductors with 336 Oriole ACSR. In addition, the Project scope consists of replacing Pumco steel poles with tubular steel poles (TSPs), replacing wood three-pole dead-end structures with three-pole TSPs, replacing wood H-frame structures with light weight steel (LWS) H-frame structures, and replacing one single wood pole with a single pole TSP. Together, these actions work to increase clearances between the conductor and other energized conductors or the ground. Temporary disturbance associated with each type of work area is described below.
Ground-disturbing activities associated with Project implementation will be limited to disturbance areas defined in the Project data as a structure work area, wire setup site, or guard structure location. Existing materials yards will be used for staging equipment and materials and as a place for personnel to meet. In addition, existing ROW access roads are associated with the Project. These temporary disturbance areas are described in better detail in the following paragraphs. For the existing structure locations where structure replacement will not occur, the existing hardware that suspends the conductors will be replaced. Because no ground-disturbing activities will occur, these remaining pole locations have not been assigned an associated disturbance area in the Project data.
Structure Installation:
For each structure leg, one (1) new concrete foundation will be installed
to support the new structure. A drill rig will drill the hole. The excavated
material from the hole will be used to create a level pad for the crane to
stage. Once the foundations have been drilled, a rebar cage will be placed into
the foundation hole. The footing steel will then be set by the civil crews and
concrete will be poured to fill each foundation hole. The concrete will be
delivered in ready-mixed concrete trucks, approximately 2 to 3 concrete truck
loads. An outage may not be required to drill the foundations if a LoDrill can
be used, but an outage will be required to set the rebar cage. The civil crew
will be made up of 4-6 personnel and will take approximately 2-3 days to
complete foundation.
Once the concrete footing has cured (2-3 weeks), the crew will arrange to have the TSPs delivered to the site using a flatbed truck. The TSPs will be offloaded by either a crane or RT forklift. Each section of the structure will be erected and assembled with a crane. Once the vertical legs are installed, the crew will place the cross member horizontally between the two (or three) upright poles and install the arms. It will take a 5-8 person crew approximately 3-4 days to erect the structure.
Structure Removal:
Once the crews are finished with the installation of the new structures,
the old structures will be torn down in sections. A crane will be used to hold
the structure while portions are cut or unbolted and removed. A crew will
further dismantle the structure on the ground. The sections will be sheared on
site and disposed in bins or broken down into sections that can be hauled off
with a flatbed truck. The foundations of the old structures will be excavated
two (2) feet below ground grade and cut off, and the excavated area around the
foundation will be back filled with the excavated dirt. It will take a crew of
4-6 personnel approximately 1-2 days to complete structure wreck-out.
Re-Conductoring:
Every structure along the line will have to be accessed for hardware
replacement and reconductoring activities. Structures will be accessed by
rubber tired pick-up trucks and bucket trucks using existing spur roads, or by
foot if spur roads do not exist. Structures may also be accessed via
helicopter. The existing conductor will be “rigged” and lifted out of the
existing conductor shoe. The existing ceramic insulator strings will be
replaced with new polymer type insulators, including all the associated
hardware used to pin the insulator to the tower. Then a roller, approximately
25-30 inches in diameter will be hung from the bottom of the newly installed
insulator and the old conductor will be placed into the roller so it can be
pulled out and replaced with new conductor. Similar activities will take place
for the overhead ground wire. This whole process should take about 2-3 hours
per tower and will involve 3-5 workers. All work will be completed from the
existing access road footprint.
Once the new conductor has been installed and sagged in that section the crews will come back to each tower, take the conductor out of the rollers and then “clip” it in to the new conductor shoe. This process should take 2-3 hours and would involve 3-5 workmen using the same type of equipment.
Work Activities for the Removal of Line Sleeves
Due to safety concerns, existing line sleeves (a device which is used to splice conductors together) are typically “cut out” and replaced with pulling socks (a device that will connect the two ends of the conductor back together). The old line sleeves could separate during the installation phase of the new conductor, so they need to be replaced with line socks. These line sleeves are typically located mid-span between two structures. Cutting the sleeves out and installing socks requires access from the ground (typically with a boom truck).
Work Activities to Install Guard Structures
Guard structures usually consist of two (2) wood pole “up-rights” and one (1) wood pole in a horizontal position at the top of the up-rights, which looks similar to an H-frame. These structures will keep the moving conductors from touching the ground or making contact with electrical circuits. These structures are used to protect existing road crossings, electrical crossings and river crossings. Guard structures could be between 40’ to 100’ high, depending on the crossing being protected. To install the guard structures, holes will be drilled with a drill rig, approximately 24 to 38 inches in diameter and approximately four to ten feet deep. The wood pole uprights are then set into the holes using boom truck-like equipment. On top of the upright structures a wood pole crossarm will be hung. This process can take a crew 2-3 hours to complete. After the new conductor has been installed and “clipped-in”, the guard structures will be removed and the holes will be filled and compacted in with native dirt.
Where feasible, “flower pots” or boom trucks may also be used to guard crossings and reduce ground disturbing activity. Rubber-tired boom trucks will stage on the road shoulder and use the boom to protect the crossing from the moving conductor above. Flower pots consist of setting each of the upright wood poles in a concrete base. The concrete base is then set on the ground surface (digging/drilling is not necessary). Minimal ground disturbance, including light grading, is necessary to set the flower pots.
Work areas for those crossings where guard structures will be required have been mapped in the GIS data.
Work Activities at Pulling/Tensioning/Snubbing Sites
Pulling/Tensioning/Snubbing Sites are required in order to pull out the existing conductors and install the new conductors. They are required at specific locations along the entire length of the reconductor portion of the project. A large majority of the pulling/tensioning/snubbing sites have been selected so that minimal blading, grading, and grubbing will be required. The equipment will “drive and crush” to the site; no access roads will be required for pulling/tensioning/snubbing sites. Minor leveling may be required to provide a flat surface for the equipment to stage. At the pulling end, a machine with a take-up reel mounted on a truck chassis will be connected to the existing conductor. The existing conductor will be connected to the new conductor at the tensioning end. As the existing conductor is being pulled out, the new conductor is being pulled in. Attached to the puller is a reel, which winds up/takes up the existing conductor. This reel can hold several thousand feet of old conductor. Once the reel is full, a crane or forklift will be used to remove the full reel and replace it with an empty reel. The process is repeated until all the old conductor located in that “pull” section has been removed and replaced with the new conductor.
At the tensioning end of the pull, a machine is mounted on a truck which has a bullwheel. Behind this machine is a conductor reel truck (or trailer) with the new conductor reels mounted on it. The conductor is “fed” through the tensioning machine bullwheel that acts as a braking device as the conductor is being “paid” out.
At both pulling and tensioning sites, a “dead-man” and field snub may be necessary to secure the conductors and free them from the pulling and tensioning machines. A field snub consists of an excavated trench approximately 20 feet long, 3 feet wide, and approximately 10 to 15 feet deep. A section of wood pole is placed at the bottom of the excavated trench, which has several steel slings going under the wood pole and back up to the surface of the ground. The excavated trench is back filled with the eyes of the steel sling protruding out of the ground. The conductor is then connected to the steel slings eyes. Once the conductor has been brought to final sag and the two ends of the conductors are sleeved together, the conductor is let up. The steel slings that were placed under the buried wood pole are removed and the process is repeated at the next pulling/tensioning site. If field snubs are infeasible, the crew may rig the conductors to a piece of heavy construction equipment.
These sites vary in size from 0.04 to 0.52 acres, will be located within the ROW, and will be accessed from the existing roads via drive and crush (overland travel). Wire setup sites have been chosen to minimize ground disturbance and avoid impacts to sensitive resources. Pulling activities will require a crew of 8-12 workmen. Each pull should take 7-10 days. A bulldozer or equivalent type of equipment with a sagging winch will connect to the new conductor and pull it to final sag.
Work Activities at Sleeve/Splice Sites
In an effort to reduce ground disturbance as much as possible, pulling/tensioning/snubbing sites have been spaced much farther apart than usual. As a result, multiple reels of new conductor will have to be sleeved/spliced together for each “pull” section (per each phase). While the new conductor is being pulled in, the reels will be “socked” together (this is only temporary). Once the pulling operation is complete, a sleeve will be installed to permanently splice the reels together. Installing the sleeves will require access to the sleeve locations from the ground. Sleeve/Splice Sites have been mapped in the project GIS to show where this operation will take place. A boom truck will access each of these sites and crews will be lifted up to press the sleeves. This method of sleeving/splicing multiple reels per pull section drastically reduced the number of pulling/tensioning/snubbing sites.
The Project sites will be accessed via existing access roads that meander parallel with the alignment, inside and outside the ROW. The access roads extend towards the ROW from Kaiser Truck Road, Eagle Mountain Road, Chuckwalla Valley Road, and Hobsonway, as well as from several unpaved dirt roads (for example, in the vicinity of the portion of the ROW that extends 1 1/4 mile east from the intersection of Paled Dunes Road and I-10; also extending 1 1/4 mile from Citrus Drive east towards the ROW near Blythe; and one-quarter mile west of the intersection of Hobsonway and Keim Boulevard near Blythe). The majority of the existing structure locations include a previously disturbed operations and maintenance (O&M) work area contiguous with the access roads. No new permanent roads will be constructed for the Project.
The Project has been designed to minimize impacts to native vegetation and sensitive resources by utilizing existing developed/disturbed areas such as existing access roads, O&M areas associated with each existing structure, and other developed/disturbed areas. Structure work areas, wire setup sites, and guard structure locations have been conservatively designed to include the minimum area necessary to safely and effectively complete the work. Within each work area, care will be taken to avoid sensitive resources. Disturbance areas and environmentally sensitive areas will be clearly delineation and workers will limit the construction activities accordingly. ‘Drive and crush” practices will be favored over clearing and grading where feasible. The construction equipment utilized will be limited to lightweight and predominantly rubber-tired vehicles, which minimize ground-disturbance. For the remaining structure locations without designated disturbance areas, workers will access the structures on foot to the extent possible. Workers will park personal vehicles and equipment such as cranes within the existing roadways, O&M work areas, other developed/disturbed areas, or designated disturbance areas.