Wet soil probably contributed to an underground electric line in Pierre failing due to a fault — like a short — causing a power outage in two main sections of the city from midnight to 4:30 a.m., Wednesday, May 8, affecting about 1,500 customers, said Brad Palmer.
He’s the city’s utilities director and told the Capital Journal it was a larger and longer power outage than is typical in Pierre; including about 21 percent of the city’s 7,200 customers of the municipal electrical utility.
Having that many out of power for that long “is pretty big for us,” Palmer said.
Many saw the effect: some traffic signals this morning were on “flash mode,” during the morning commute, Palmer said.
It’s difficult to describe the exact geographic stretch of such an outage because the city’s system of four substations starts switching circuits to fill in outages so there can be “legs” of outage areas some distance from a main area out of power.
But generally, the outage happened from Ree Street to Highland Avenue, including part of Euclid Avenue and from North Harrison down to Sully Avenue right along the Missouri River in the southeast part of the city, according to Palmer. While those areas generally are east and south of downtown, there are exceptions, he said.
The Capital Journal, at 333 West Dakota Avenue, for example, lost power for a time early Wednesday.
Blame it on the rain.
“It’s probably groundwater related,” Palmer said of the cable under Ree Street.
Some of the city’s older electric cables were put underground in the 1960s and 1970s, with the insulated line laid directly into the soil, which often is of a corrosive nature in this Pierre shale locale, Palmer said. In a year like this, with a wet spring, “a little water will find its way into a power line that’s corroded,” causing a fault, or short, he said.
Now, live, this special bulletin: It has has been a wet spring.
A total of 1.55 inches of rain has fallen on Pierre from Monday through 10 a.m. Wednesday, May 8, in two rain systems, said Mike Connelly of the National Weather Service office in Aberdeen.
That’s well above normal, as 2019 has been so far.
Since Jan. 1, through midnight Tuesday, May 7, Pierre has seen 8.37 inches of precipitation fall upon it; that’s 3.71 inches above the 30-year average, which is called the norm, for the 4.25 month period, according to weather service records.
Meanwhile, the temperature has been about 15 degrees below normal and on Friday morning this week might dip to 30 degrees, Connelly said. Snow fell in the Black Hills early today and on Tuesday, too, he said.
The bad cable hasn’t been dug up yet until the forensics are complete.
The utilities crew might put “pipe,” or plastic PVC conduit into the ground to ensconce the new or fixed power cable to keep it from encountering the corrosive and sometimes wet soils.
That’s how power cables in recent years have been buried.
The outage could have been worse, with real stuff hitting the fan.
But the fact it happened during the darkest part of the night was a good thing, collectively, in that regard, proving that stuff doesn’t always happen.
“We did have some (sewage) lift stations out of power, but we have not had any reports of any backup into houses,” Palmer said.
Other water-moving pumps were affected, too, he said.
“But in the middle of the night, usage is pretty low so that was not an issue for us.”