A leader in the underground transmission industry, Wilson’s underground transmission group has installed over 2,100,000 feet of XLPE cable through 345kV including 770 terminations and 775 splices nationwide. With more underground cable installation experience than virtually any other contractor in the nation, our expertise assures our clients of a superior product installation and quality, on-time performance.
Wilson's underground transmission group's roots date back to 1986 with a resume of nearly 60 projects. From solid dielectric to high pressure fluid-filled cables, we have the transmission expertise to tackle the most complex projects with success. This includes the ability to lead EPC projects with the added benefit of utilizing any of our specialty services to meet the turnkey needs of any multifaceted project. Staying ahead of the competition through safety conscious operations and quality design/build construction services we have earned our client’s trust, confidence, and repeat business time and time again.
Proven Expertise – From Planning Through Performance
AV Solar Ranch 1 Project, 230kV Underground Transmission Line, CA
On this underground transmission project Wilson was responsible to furnish and install 11,500’ of transmission duct bank and seven transmission vaults. The work also included the installation of 34,500’ of Owner-provided 230kV 2500kcmil AL Cable and the support of the cable manufacturer with jointing of splices (18 ea.) and terminations (12 ea.). Wilson teamed with a southern California civil subcontractor experienced with local conditions for the installation of the duct bank. Permitting delays lead to late start on an already aggressive schedule. Hot temperatures and the nearly constant presence of wind (the Antelope Valley is a hotbed for Renewable Energy Development) created difficult work conditions. Dust Control and environmental compliance was critical. Unique challenges that Wilson overcame on this project included three tall riser structures requiring full scaffolding with stairs shrink wrapped for protection from the environment while performing termination work. Aluminum cable conductor created a challenge to splicing activities in confined space (vaults) which required the workers to be trained and certified in the use of SCBA (self-contained breathing apparatus) to perform work on supplied air.
Flamingo Underground Conversion Project, NV
Wilson Construction Co. was successfully chosen as the prime EPC contractor for the Nevada Energy Flamingo Underground Conversion Project located in Las Vegas, Nevada. As prime contractor, Wilson was responsible for the detailed engineering design, procurement of major materials and construction of the multifaceted project to convert an overhead transmission corridor, bisecting private property, to an underground system within the public right of way.
Highlights of the project included nearly two miles of double circuit transmission duct bank with ten transmission vaults, nearly two and a half miles of distribution duct bank, installation of over 40,000’ of XLPE 138kV cable/ 30 high voltage splices/ 18 open air terminations, installation of 7 self supporting foundations and poles and the removal and demolition of over 40 steel structures. The complex underground build out was constructed in the right of way Flamingo Blvd. at minimum depths of 13’ including crossing the world famous intersection of Flamingo Road & Las Vegas Boulevard (better known as “The Strip”) four separate times. The location is considered one of the busiest intersections in the world coupled with nearby pedestrian traffic in which thousands of visitors a day make their way along “The Strip” touring the local Casinos. In addition to traffic and congestion, the construction of the underground system also encountered difficult digging conditions consisting of hard rock (caliche), ground water and contaminated soil. Every day brought a new issue for the project team to work through and resolve. This unique and multi-faceted project catered well to the many different specialty disciplines that comprise Wilson Construction. Wilson self-performed services on the project from the following in-house divisions and departments: overhead transmission, underground transmission, drilling & foundations, environmental and substations. Wilson’s ability to pull resources from each of these in-house specialties, coupled with our construction and engineering partners, allowed for a symbiotic relationship that benefitted planning, scheduling, coordination, construction and compliance that proved key in constructing the project on time and under budget and with no recordable injuries.
Sinatra 230kV Loop In Underground Project, NV
Wilson Construction Co. had a little lady luck on its side last summer when Nevada Energy awarded our team the Sinatra 230kV Loop-In Project located in Las Vegas, NV to Wilson Construction Co. The project consisted of one mile of two double circuit duct banks, eight transmission vaults, 12 each open air and GIS terminations and 36 splices all to be completed under a tight performance schedule. The Sinatra project embodied all of Wilson’s underground transmission capabilities in that it combined not only cable installation and civil construction, but also splicing of open air terminations on steel poles and GIS terminations in a substation.
To meet the project completion dates, the 48 cable pulls were performed non-sequentially, typically in sets of six. Among the highlights of the civil work was a 26ft deep excavation to tie the duct banks into existing bore casings under Interstate I-15 and two separate crossings under an 84” transmission water line at a depth of 23ft deep.
South Bay Power Station (OMPPA) Underground Transmission Line Project, CA
This project consisted of the installation of double circuit 230kV transmission line. The project encompasses two segments of the Otay-Mesa Power Loop which is over 10 miles of duct bank equating to over 320,000 lf of cable installation, 210 splices, and 24 terminations. Wilson’s scope included the cable pulling as well as supporting the cable manufacturer’s jointing teams. The cable was manufactured by Silec Cable of France.
Segment five of the project originates in the active SDG&E Old Town Substation and meanders along the famous Pacific Coast Highway through Downtown San Diego where it transitions to overhead south of downtown in the shipyards. Segment 3 originates at a transition structure in National City where it is goes underground through a 3500’ directional drill under the environmentally sensitive Sweetwater Marsh continuing through heavy industrial facilities located in Chula Vista where it finally transitions back to overhead at the South Bay Power Plant.
Kendall Yards 115kV Underground Transmission Line Project, WA
Wilson Construction Company recently installed a 115kV underground transmission cable connecting the College/Walnut Substation to the Post Street Substation for Avista Utilities. The project included installation of the cable, grounding, racking and support structures as well as support of the cable manufacturers jointing teams to install six 115kV splices and six terminations. The new underground line consisted of three underground segments totaling ¾ of a mile.
This project proved to have many challenges unlike the typical underground project. Challenges included installing cable into a substation where the cable terminated on the first floor of an indoor substation where the duct bank ended at the basement wall of the building, one level below the station bays and without cable trays, cable supports or any pre-arranged pulling eye locations to rig to. Wilson Construction crews also faced heavy snow fall and cold temperatures as work begun in early February, 2008 and was completed in March, 2008.
Home Payne Substation to Cathedral Square -- BC Hydro 230kV SCFF Transmission Line, British Columbia
This project involved the installation of nearly six miles of underground 230kV PPLP cable. It was Wilson Construction's first truly international project.
For this project BC Hydro elected to contract directly with the cable manufacturer for both supply and installation of the cable system. Fujikura America, Inc. in turn contracted the cable installation to Wilson Construction. This line was for a major trunk line going from BC Hydro's famous Cathedral Substation east to the Horn Payne Substation. The entire project was located in busy city and residential streets. The project was completed without incident and the owner and Fujikura were both extremely satisfied with the project.
Mississippi River Crossing, 230kV Transmission Line, LA
This extraordinary project consisted of the installation of a 230kV transmission line underneath the Mississippi River. To accomplish the work, Entergy negotiated the bore under separate contract and issued a single RFP to the cable manufacturers for supply and installation of two circuits of 230kV XLPE cable. The RFP also required the supply and installation of a spare cable for each circuit as well.
Wilson Construction was awarded the contract by J-Power Corp./Sumitomo Electric for the installation and termination of eight 230kV cables. The cables were a 2500mm2 segmental CU conductor and utilized individually insulated strands to eliminate the skin effect. The total length of the run was approximately 3,300 feet.
Center Substation 345kV Solid Dielectric Interconnects
This project included the design, procurement, and construction of the underground duct bank, cable system and GIS pits for five each 345kV solid dielectric cable interconnects from the Independent Power Producer plant to the GIS equipment in Deer Park, Texas.
The project consisted of approximately 8000 ft. of 630mm2 345kV XLPE copper cable, 15 GIS terminators and 15 open-air terminators. Project requirements included designing a GIS pit to incorporate five circuits, with cables to be installed at different times over a two-year period. The cables installed first were to be energized before the next cables would be pulled, creating significant safety issues for the field installation. We designed the GIS cable pit so that the cable would be installed in conduits all the way to the GIS terminator. In this way the GIS pit was dug open one time, conduits were installed and the pit closed. With the conduits already installed for all five circuits, pulling the remaining cables became a much easier and safer job.
First 345kV XLPE underground transmission contract in the
U.S. Mystic Station 345kV & 115kV and Fore River Station 115kV Projects, MA
This project involved the high voltage interconnect for two power plants in the
The Fore River Station is a 800MW plant and included three circuits of 1400mm2 CU 115kV cable with two conductors per phase. The plant end of these cables terminated into GIS equipment while the three utility termination points were open air.
Los Medanos Energy Center/Delta Energy Center OSBL Electrical Underground & Overhead Transmission Lines, CA
One of the largest 230kV projects in the U.S., this fast-track EPC contract included the 115kV and 230kV transmission lines interconnect for the Los Medanos Energy Center (LMEC) and Delta Energy Center (DEC). Both the LMEC (500 MW) and the DEC (880MW) plants are combined cycle cogeneration plants. The LMEC interconnect involved approximately 5,000 feet of overhead and 5,000 feet of underground 115kV transmission line. This two-circuit line included overhead bundled 2300kCMIL and underground 3000kCMIL with two conductors per phase. The underground portion was completed with two splice points in the circuit and approximately 60,000 feet of solid dielectric cable. The base contract included only the underground portion of the DEC 230kV interconnect and utilized 2500kCMIL conductor with two circuits and two conductors per phase. The DEC line required five splice points and involved approximately 120,000 feet of solid dielectric cable.