Board approves Alliant Energy substation conditional use permit near Bertram with screening, stormwater conditions

The Linn County Board of Adjustment voted Dec. 30 to approve a conditional use permit for an Alliant Energy electrical substation on a roughly 3-acre site near Knapp Road and McRoberts, south of Bertram.

Planning staff told the board the substation footprint is smaller than the parcel and that the project had previously been granted approval in 2014 but exceeded the five-year construction-start requirement, necessitating a new conditional use review. Staff said the site is agricultural and that utility substation use is allowed in the district with a CUP; staff recommended approval with conditions including additional vegetative screening and stormwater controls to address a drainage-way restriction.

"We recommend alternative 1," the staff presenter said, summarizing the recommendation to grant the permit with conditions. Staff described required downcast lighting to limit off-site illumination and said vegetative screening had been expanded to the west and south of the fenced substation area following neighbor concerns.

Applicant representatives said the control building will have a downcast light on a photocell "that shines straight down" and that floodlights would be used only for maintenance or emergency work. "The control building will have a light on it that is downcast that's on a photo cell. But it shines straight down. It is not a broadcast light," the project's engineer said.

The applicant said live screening—evergreens supplemented by deciduous trees—will be planted around the fenced area except where a transmission line enters on the east side, and that a stormwater-management feature to the west will be reviewed by John Gallagher with the Natural Resources Conservation Service as a design consideration.

Neighbors had submitted emails and attended prior meetings; staff said most concerns were addressed by adding screening and clarifying lighting measures. The county noted minimal regular traffic generated by substations once constructed but observed that emergency access could be required on occasion.

A board member moved to accept staff findings and approve PC250012 as recommended; the motion was seconded and carried by roll call: Alden, Meader, Price and Hoover each recorded a "yes." Conditions attached to the approval included the expanded vegetative screening, required downcast lighting, and stormwater review by NRCS.

Because the project previously had an approval that lapsed, planning staff and the applicant will coordinate remaining technical reviews and any permits required by secondary road or stormwater authorities before construction.