Hawaiian Electric Company, in a Jan. 17 application, requested a Public Utilities Commission of Hawai’i determination that two 46-kV subtransmission lines be built above and below the surface of the ground, in relation to its proposed project involving the new Mauka substation.
As noted in the filing, the U.S. Army’s planned Command and Control Facility (C2F) project at Fort Shafter requires an expansion of Hawaiian Electric’s existing Fort Shafter substation. To improve the physical security of their electricity supply, instead of upgrading the existing substation, the Army has requested a new point of service – the Mauka substation – further within the Fort Shafter base perimeter fence.
Toward that end, the company added, the proposed Mauka substation includes the installation of two 46-kV underground feeders, both of which are located on the Army’s Fort Shafter base.
The company said that it proposes to place those feeders underground in ducts that the Army would build and transfer to Hawaiian Electric in connection with the project. The Army has requested that the proposed 46-kV lines be installed underground, the company said, adding that the Army has agreed to pay for the entire cost of the project, less the cost the company would have incurred to upgrade the existing substation to accommodate the load growth.
Further discussing the project, the company said that it involves the proposed construction of 46-kV underground line extensions, with short overhead line extensions from existing 46-kV transmission lines. Hawai’i Revised Statute (HRS) § 269-27.5 provides that whenever a public utility plans to place, build, erect, or otherwise build a new 46-kV or greater high-voltage electric transmission system above the surface of the ground through any residential area, the commission is to conduct a public hearing prior to its issuance of approval thereof, the company said.
The company noted that it does not believe that HRS § 269-27.5 applies to the proposed overhead sections of 46-kV line extensions because all project facilities are on military property and the closest existing residence to the proposed overhead line extensions is located about 115 feet away on Middle Street.
In addition, the overhead facilities in the project are limited to two riser poles in the same approximate areas as existing poles and lines and the rest of the outside facilities in the project are underground.
Hawaiian Electric added that it is proposing to install about 1,800 linear feet (two 46-kV circuits) of 1500KCM 46-kV underground cable from the existing poles along Middle Street to the Mauka substation in the new five-inch ducts and six-foot by 14-foot manholes installed by the Army. The undergrounding of the 46-kV subtransmission circuit in the new Army-constructed ducts was requested by the Army to accommodate projected new load and for energy security reasons, the company said.
The Army would pay the entire estimated project cost less the estimated cost to install one transformer at the existing substation to serve the new C2F, under the company’s normal practice. Hawaiian Electric added that the reason for the credit – of one transformer – is that Hawaiian Electric would have had to otherwise install one transformer at the existing Hawaiian Electric Fort Shafter substation to meet the increased load.
The C2F load is estimated at about 10 MVA, and the existing load at the existing substation is recorded at 7 MVA, the company said, adding that service from the new substation is required by March 2020, to coincide with the completion of the main building at the end of “Phase 3,” when the capacity at the existing Fort Shafter substation will no longer be able to accommodate the additional load.
The project has been broken down into the installation of the Fort Shafter line extensions, and the installation of the Mauka substation, which includes the installation of a new dedicated, low-profile substation with three new 46-12.47-kV 10/12.5 MVA transformers, three 15-kV switchgears and related electrical equipment; and telecommunications link to the new Mauka substation for 46-kV substation remote monitoring and control.
The estimated total cost for the installation of the Mauka substation is about $9.6m, Hawaiian Electric added, noting that its net cost, after crediting the estimated cost of installing one transformer at the existing substation and including AFUDC, is about $2m. The estimated total cost for the installation of the Fort Shafter line extensions is about $2.1m, the company said, adding that its net cost is $0 after Army contributions.
Among other things, the company said that, if the project is approved, it is targeting to place the 46-kV circuits in service by March 2020, with construction expected to begin in February 2018.