(WWJ) DTE energy crews are following up repairs at 6,000 locations across their service area, where temporary fixes were made at the height of last month’s biggest storm in utility history.

Over 800,000 customers were without power, some for over a week.

DTE Vice President Heather Rivard — at the site of one of the repair jobs on Detroit’s west side this morning — said they are making long-term improvements.

“We’ve been trying for the last decade or so within the local economic conditions and extend the serviceable life of our equipment as long as possible, but we’re now in a period of heavy investment over the last couple of years and going into the next several years to improve the overall reliability of our grid,” Rivard said.

Rivard says new technology and equipment are allowing them to “harden” the grid to make it less susceptible to outages.

Some of the components are currently 60 years old.

“At the end of it all our system will be not only back to normal, but in many cases it will be better than it was before we started because we are replacing many parts of our infrastructure with brand-new equipment,” she said.

But there’s one thing they don’t control: Usually 60 to 70 percent of outages are based on tree interference, but in the past storm it was more like 85 percent.

“We want to have trees in or territory, we just want to have them in a spot that’s maybe farther away from the electrical lines,” she said, adding they’re trimming and removing trees. She added that through its foundation, DTE also plants trees.

Strong storms with lashing rain weakened the root systems of trees, especially older trees, making them easier to uproot, many said.