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Power Distribution

Distribution Conversion

July 29, 2021

Distribution Conversion

before after

Redwood falls project
Improves equipment, safety and aesthetics of Downtown Area

Project Owner:
Redwood Falls Public Utilities

Key Experience:

  • Responsibility and involvement throughout the project, from initial planning and design to construction administration and contract closeout
  • Development of a multi-year plan for staged construction of the improvements
  • Coordination with private communications utilities including joint use of excavations

Key Features:

  • Replacement of old overhead infrastructure with new underground infrastructure, to increase reliability and improve aesthetics
  • Eliminated public safety concern of old transformer platform structures

The electric distribution lines in the downtown alleys of Redwood Falls, MN consisted of large overhead structures which included transformers mounted on platforms. Due to concerns with the age and condition of the structures, along with safety clearances to energized equipment and conductors, a project was undertaken to replace the old infrastructure with new underground lines and associated padmount equipment. In addition, these improvements would improve the overall attractiveness of the area.

The project was split into two phases to allow for completion over two construction seasons. Phase 1 included four blocks of downtown area, and the second phase included seven blocks. In addition to burying the overhead primary circuitry, the project also converted most of the overhead secondary circuitry associated with the conversion area to underground.

DGR Engineering (DGR) developed a full design for the new underground circuitry, including equipment and cable sizing, equipment locations, line routes, and material lists. Bidding and contract documents for construction of the improvements were developed which included detailed design drawings, staking sheets, and technical specifications. DGR worked with utility staff to determine where new easements would be needed for placement of padmount equipment.


The project was designed to allow for directional boring of the cables wherever practical, and for trench excavation when needed, due to the quantity and/or location of underground cables and ducts. Sections of pavement were removed when required and subsequently replaced with new concrete after the installation of new raceways was finished.

Contractors completed the boring, excavation, and surface repair work; and the installation of raceways, primary and

secondary cables, box pads, ground sleeves, and secondary boxes and cabinets. The utility completed the installation of padmount transformers and switches, primary cabinets, cable terminations, and meters. The utility also performed all equipment cutovers and energization, and removed the existing overhead lines and related facilities. The completed project resulted in a safer and more aesthetically pleasing downtown area that was also up to current standards for infrastructure and reliability.


Mainline Distribution Circuits

October 5, 2018

The project included the construction of three new mainline 13.8 kV circuits on the City’s distribution system to increase capacity and reliability.   The circuits were built in underground fashion; two extending from the City’s substation near the airport to the downtown area, and one extending from the City’s substation near the airport to the event center.  DGR services for this project included the initial study work, project development, engineering design, permitting, construction administration, and resident construction observation.

Electrical Distribution Conversion

October 4, 2018

The project included full services for the conversion of the utility’s distribution circuitry from overhead to underground.  The conversion was completed in several project phases as part of a multi-year process.  The project also included the construction of several new circuits that were integrated to new substations being built in the same timeframe.  DGR services for the project included the reliability study work, preliminary planning, permitting, engineering design, material procurement assistance, construction administration, and resident project observation.

Coordination Study

October 2, 2018

DGR provided a device by device coordination study for the Willmar Municipal Utilities electric distribution system.

Utilizing Milsoft’s Windmil® and Light Table® software we were able to develop a system wide coordination philosophy designed to grow and develop as their system grows.

Utilizing a “zone coordination scheme” we provided recommended settings for relays in each substation as well as proper fuse and VFI selection on the distribution circuits.

The project proved to be challenging on a number of levels, including designing a coordination philosophy flexible enough to handle the activation/deactivation of local system generation.

The distribution coordination project dovetailed into a full 69 kV transmission system loop coordination analysis.

Line Tap

October 2, 2018

The project included full services for a 1.4 mile 115 kV line. The project required coordination with many different entities, including other power companies for coordinating the interconnection, and with a railroad company for right-of-way permitting, which included coordinating an inductive interference study.

DGR services for this project included permitting, coordinating the design survey, design, construction administration, construction staking, and resident project observation.