>Yahoo! is not affiliated with the authors of this page or responsible for its content.
STATE OF VERMONT PUBLIC SERVICE BOARD Docket No. 6928 STATE OF VERMONT
PUBLIC SERVICE BOARD
Docket No. 6928
Petition of Green Mountain Power Corporation
for a certificate of public good, pursuant to
30 V.S.A. § 248(j), for Authority to Upgrade the
Transformers at the Mallets Bay and Iroquois
Substations in Colchester
)
)
)
)
)
Order entered: 6/28/2004
I.

I
NTRODUCTION
This case involves a petition filed by Green Mountain Power Corporation ("GMP") on
February 9, 2004, requesting issuance of a certificate of public good ("CPG") by the Vermont
Public Service Board ("Board") pursuant to 30 V.S.A. § 248(j) for the proposed upgrade of the
existing 10 MVA transformer at its Mallets Bay Substation #34 to a new 10/14 MVA
transformer, and the replacement of the 5/7 MVA Iroquois Substation #81 transformer with the
10 MVA transformer removed from Mallets Bay Substation #34. On May 3, 2004, GMP filed
amended prefiled testimony to reflect the fact that the new 10/14 MVA transformer proposed for
installation at Mallets Bay will be a spare transformer taken from GMP's stock, and to address
questions or concerns expressed by the Vermont Department of Public Service ("DPS" or
"Department"). On May 18, 2004, the Board requested the following material from GMP: a site
plan of each substation showing existing and proposed conditions; additional information
regarding the undergrounding of exit feeds from the Iroquois Substation; and additional
information regarding changes in structure height. On June 16, 2004, the Board received the
information requested on May 18, 2004.
Notice of the filing in this docket was sent on March 30, 2004, to all parties specified in
30 V.S.A. § 248(a)(4)(C) and all other interested parties. The notice stated that any party
wishing to submit comments as to whether the petition raises a significant issue with respect to
the substantive criteria of 30 V.S.A. § 248 needed to file their comments with the Board on or
before May 3, 2004. In addition, notice was published in the Burlington Free Press on April 5
and April 12, 2004, stating that any party wishing to submit comments as to whether the petition Docket No. 6928
Page 2
raises a significant issue with respect to the substantive criteria of 30 V.S.A. § 248 needed to file
comments with the Board on or before May 3, 2004.
On April 21, 2004, comments were received from the Vermont Agency of Natural
Resources ("ANR"), which stated that the proposed project does not appear to raise any
significant concerns for the ANR pursuant to 30 V.S.A. § 248(j), and that the ANR does not
request a hearing.
On May 3, 2004, comments were received from the Department, which stated that the
petition, as described in the amended prefiled testimony of GMP witness Dean Denis filed on
May 3, does not appear to raise any significant issues with respect to the substantive criteria of
30 V.S.A. § 248. The Department also does not request a hearing.
The Board has reviewed the petition and accompanying documents and agrees that,
pursuant to 30 V.S.A. § 248(j), a CPG should be issued without the notice and hearings
otherwise required by 30 V.S.A. § 248.
II.

F
INDINGS
1. GMP proposes to install a new 10/14 MVA transformer for the Mallets Bay Substation.
The existing Mallets Bay 10 MVA transformer will be installed at the Iroquois Substation
allowing for the conversion of the Iroquois 81J1 and 81J2 feeders from 4.16 kV to 12.47 kV, to
match those of Mallets Bay (the "Project"). Petition; Denis pf. at 1.
2. The Iroquois conversion along with the Mallets Bay transformer upgrade will provide
the following major benefits:
!The Mallets Bay Substation is loop sourced and can sustain a single transmission source
outage contingency; the Iroquois Substation cannot, since it is radially sourced, and would be
very difficult to loop source due to right-of-way constraints in the area. This Project will increase
the reliability to the customers served from the Iroquois Substation by allowing for feeder
back-up from the Mallets Bay Substation.
!Decrease losses on the Iroquois feeders by converting them to a higher voltage.
!Allows for feeder backup on all feeders which will increase reliability even during daily
work procedures. Docket No. 6928
Page 3
!Relieves high loading on the Mallets Bay Substation #34 by transferring portions of
load from the 34G2 feeder to the converted 81J1 and 81J2 feeders. (Redistribution of load
among the three feeders). Denis pf. at 2.
3. At present the 34G2, 81J1 and 81J2 all have tie points that can be utilized for feeder
backup if the Iroquois Substation is converted to higher voltage (from 4 kV to 12.47 kV). GMP
would extend the coverage of the 81J1 and 81J2 circuits to permanently pick up selected portions
of the 34G2 line. With this reconfiguration of existing circuits, full feeder backup of either
feeder is achievable. Denis pf. at 2.
4. GMP has stated that the construction to complete the Project will comply with the latest
National Electrical Safety Code Requirements in compliance with Board Rule 3.500. Denis pf.
at 5.
5. Presently, the capacity of the Mallets Bay Substation is 10.5 MVA. In the summer of
2003, the peak reached 8.91 MVA. According to the Peak Summer Station Load Forecast, the
substation will be at capacity in 2006. The 34G2 feeder is responsible for 62% of the total
Mallets Bay peak load, or roughly 5.5 MVA in 2003. If the proposed reconfigurations of the
81J1 and 81J2 feeders take place, the peak load on the 34G2 feeder will be reduced to
approximately 2.6 MVA, thus decreasing the Substation total load to 6.02 MVA. Denis pf. at 3.
6. GMP plans to replace and upgrade the transformer at Mallets Bay, with installation of
the existing Mallets Bay transformer at Iroquois, rather than install a new transformer at Iroquois,
because of the greater benefits which can be achieved at an approximately similar cost. Installing
the new transformer at Mallets Bay and replacing the existing transformer at Iroquois with the
existing Mallets Bay transformer not only allows for the necessary voltage conversion at
Iroquois, it offers greater system flexibility and greater room for future growth at the Mallets Bay
Substation. The larger transformer at Mallets Bay will provide added reliability for outage
contingencies of the Iroquois Substation circuits. The Project will allow the two substations to
back each other up. Currently, with the 4 kV configuration, feeder backup for Iroquois from the
adjacent Mallets Bay 12 kV circuits cannot take place. To ensure the backup capability, the
existing Mallets Bay Substation transformer needs to be replaced with one of higher capacity to
carry the existing Mallets Bay circuit loads, plus the potential Iroquois load. An additional Docket No. 6928
Page 4
benefit will be the opportunity to switch load for routine line and substation work on Iroquois
feeders. Denis pf. at 3-4.
7. The primary problems which GMP's Project address relate to reliability, and
conservation would not effectively address the problem. Denis pf. at 4; findings 2-5, above.
8. The cost of the Mallets Bay transformer upgrade and related improvements is
approximately $213,000 and includes new voltage regulators and improved oil containment. It
will be accounted for as a capital expenditure. The cost to convert the Iroquois Substation from
4.16 kV to 12.47 kV is approximately $230,000 and will be accounted for as a capital
expenditure. The cost of the voltage conversion from 4.16 kV to 12.47 kV of the two
distribution circuits out of the Iroquois Substation is approximately $430,000 and is also a capital
expenditure. Denis pf. at 4 and Attachment A.
9. GMP proposes to install improved oil spill containment for the new transformer at
Mallets Bay and for the Iroquois transformer at the Iroquois Substation consisting of a concrete
containment basin located directly under the transformers designed to hold the entire volume of
oil from each transformer, as well as 300 cubic feet of precipitation. Other equipment
improvements such as installation of three new voltage regulators and replacement of distribution
circuit breakers will also be undertaken. The exit feeders from the Iroquois Substation will be
undergrounded a distance of 153 feet to a roadside riser pole to gain additional horizontal
separation clearances, and some basic structural components will be replaced to assure the
continued integrity of the structures. Denis pf. at 4 and 5; Denis sup. pf. at 3.
10. GMP will install a spare transformer at Mallets Bay out of stock in order to meet the
schedule for completing the Project.
Orderly Development of the Region
[30 V.S.A. § 248(b)(1)]
11. The Project will not unduly interfere with the orderly development of the region, with
due consideration having been given to the recommendations of the municipal and regional
planning commissions, the recommendations of the municipal legislative bodies, and the land
conservation measures contained in the plan of any affected municipality. Letter from the Town Docket No. 6928
Page 5
of Colchester, dated January 23, 2004, and letter from the Chittenden County Regional Planning
Commission, dated February 1, 2004.
Need for Present and Future Demand for Service
[30 V.S.A. § 248(b)(2)]
12. The Project is required to meet the need for present and future demand for service which
could not otherwise be provided in a more cost effective manner through conservation programs
and measures and energy efficiency and load management measures. Findings 2-7 above.
System Stability