PIERRE | Black Hills Energy invested more than $10 million during the past three years trimming trees and other vegetation along its electricity lines, according to a report approved Tuesday by the South Dakota Public Utilities Commission.
The Rapid City-based utility intends to spend about $10 million more to continue the work during 2016 and 2017.
The company wants to get all rights-of-way trimmed within five years.
The project results from a 2012 agreement between the company and the commission to protect the utility’s distribution system.
Outages caused by trees numbered 79 in 2010 and 116 in 2011.
The disruptions fell to 55 in 2012 and, after deducting the Winter Storm Atlas damage, dropped to 52 in 2013.
The work showed results as outages dropped to 38 in 2014 and 25 through Nov. 30, 2015.
The ongoing trim cycle will be four to five years along lines that carry less than 69 kilo-volts and 10 years for lines carrying larger amounts of electricity.
PUC chairman Chris Nelson said the results looked good but expenses have been “surprisingly” more than expected.
“The numbers are higher than we had been anticipating, and we have been given an explanation why that is,” Nelson said.
He said it wouldn’t be prudent to stop the project.
The expenses exceeded $3 million for 2013, then rose past $3.2 million in 2014 and climbed above $4.4 million in 2015.
Black Hills Energy estimates vegetation management will cost nearly $6.3 million this year and be nearly $4.4 million in 2017.