Exhibit A - 115 kV Rebuild Background.pdf

Big Eddy-The Dalles 115 kV Line Rebuild/Reconductor Background:

In recent years, BPA Transmission Planning1 staff have identified the Northern Wasco County People’s Utility District (“NWCPUD”) 115 kV backbone transmission line (“115 kV Line”) as a limiting element in regional transmission planning studies. Various load and generation assumptions are factors in the analysis. The line provides a subtransmission function connecting the NWCPUD receiving substations for load service to NWCPUD customers, and a network transmission function for BPA that electrically connects Big Eddy substation to Bonneville substation through a receiving station in Hood River. Heavy Summer conditions are the most limiting. The line currently has a summer (40 C ambient) rating of 1055 amps. In recent BPA powerflow studies, the line is the limiting element with certain contingencies at its current summer rating. The objective is to achieve a rating of at least 1600 amps at 40 C ambient.

NWCPUD seeks to engage an engineering firm (“Engineer”) with the qualifications to determine the most economical and expeditious option to rebuild the 115 kV line that achieves the rating objective. In addition to reaching a rating greater than 1600 amps, NWCPUD needs to identify options for reducing fault currents in some of its receiving stations. This contract will be a Design- Build contract.

One-line Topology:

The diagram below is a simplified one-line diagram of the facilities that will be affected by the project. Power into NWCPUD comes from BPA Big Eddy Substation on the right side, but during 115 kV Line outages, load may be served for the line terminals in The Dalles Substation. The NWCPUD facilities terminate at BPA’s The Dalles Substation (T_DALLES) on the left side of the diagram.

NWCPUD owns and operates five receiving stations along the 115 kV Line that provide service to loads in the NWCPUD and WEC service areas.

1 The Bonneville Power Administration (BPA) provides Transmission Planner (TP) and Transmission Operator (TOP) reliability functions to NWCPUD under contract.

Existing Conductor Characteristics:

The following table describes the physical characteristics of the conductor comprising NWCPUD’s 115 kV line.

Description Length

(mi) Conductor Max T C The Dalles - Second Street 0.5 1272 Bittern 75 Second Street - Str 4/7 (End Ground Wire) 0.73 1272 Bittern 75 Str 4/7 (End GW) - Three Mile Tap Str 1/7 3.08 1272 Bittern 75 Three Mile Tap Str 1/7 - Columbia Heights 0.35 1272 Bittern 75 Columbia Heights - W. J. Seufert Tap 0.83 1272 Skylark 75 W. J. Seufert Tap - Ch 1 0.29 1272 Skylark 75 Ch 1 - Big Eddy 2.75 1272 Skylark 75 Total Length 8.53

The design parameters of the Bittern and Skylark conductors are shown in the table below.

Switches, Circuit Breakers and Other Series Limiting Elements:

In addition to assessing the capabilities of various new conductor options to reach the capacity objective, the Engineer shall examine all other series and shunt elements that currently limit the capacity of the 115 kV circuit. NWCPUD has identified switches and bus work that are rated below the 1600 ampere objective. Other series elements such as circuit breakers/switchers and ground switches may also need to be examined in conjunction with the fault current interrupting capacities that must be considered in the project design.

Poles:

In 2005, the sections of the 115 kV line from The Dalles Substation to Columbia Heights Substation were rebuilt – much of it on steel poles and conductored with Bittern ACSR. For the sections from Columbia Heights to Big Eddy, the age of the poles varies with BirthYears ranging from 1970 to 2003 and 2005. A thorough review of the pole conditions will be part of the initial project engineering activities. Pole replacements may be required and such replacements may be affected by constraints listed in the next section.

Design and Construction Constraints Institutional Constraints:

The Engineer must have permitting capabilities to address requirements associated with all institutions with jurisdiction along the 115 kV Line.

Portions of the 115 kV alignment are inside the City of The Dalles Urban Growth Boundary (UGB).

Under an existing Intergovernmental Agreement (IGA), NWCPUD has the authority to construct, operate and maintain transmission lines for the benefit of its customers. Consultation with the City Planning Department will be needed to ensure that any permits for new structures are obtained.

Portions of the project are also constructed in the Columbia River Gorge National Scenic Area (CGNSA). Wasco County Planning Office administers the zoning requirements for the CGNSA. The approach to achieving the capacity objective may require methods that are consistent with existing maintenance, operation and use of the facilities in this area in order to achieve the objectives including an expedited implementation schedule.

Other jurisdictions may need to be consulted with. The Engineer shall be responsible for identifying and coordinating construction activities with any affected jurisdictions.

Construction Constraints:

Terrain:

The terrain of the existing transmission alignment varies. In some areas the line is built along roads and on relatively flat areas. But a significant portion of the alignment is through rough terrain with limited access. The Engineer shall be responsible for reviewing the constructability of all new facilities and conductor stringing in the alignment.

Outage Coordination:

Because the 115 kV line is the backbone of Northern Wasco’s subtransmission system, all work must be performed while all receiving stations remain energized from either the Big Eddy Substation or The Dalles Substation terminals. The Outages of the 115 kV line are subject to outage https://www.fs.usda.gov/crgnsa coordination with BPA pursuant to the TOPIC2. A minimum notice period to BPA will be required to remove line sections for replacement. Contractors must be BPA certified clearance holders.

2 Relevant sections of the Transmission Operator Integrated Compendium Processes and Guidelines (TOPIC), version 11 or most current version will be provided by NWCPUD to Engineer.