Sandbagging Begins in Inver Grove Heights

The city’s flood preparations began in earnest on Tuesday, when city crews began sandbagging along the levee that protects the low-lying areas in Inver Grove Heights from the rapidly rising Mississippi River.

Yesterday, the National Weather Service issued a flood warning for the Mississippi River in Dakota County. Forecasters predict the river may rise by as much as nine feet by Monday, thanks in part to the relentless snow and rain the area received this week.

City officials, who have been closely monitoring the flooding predictions, are wasting no time preparing. Yesterday, city crews used over-sized sandbags to plug a gap in the levee along 64th Street in Inver Grove Heights and set up four water pumps to clear rain- and melt-water that is already accumulating behind the dike. The city is also allowing property owners whose homes may be threatened by the river to use some of the 5,000 sandbags the city purchased to protect their property.

Unlike other cities along the Mississippi, including South St. Paul, Inver Grove Heights is geographically less vulnerable to flooding, thanks to the high elevations most of the city enjoys. But city officials say that nine buildings — four homes and five businesses — lay within the city’s 100-year floodplain. Those buildings, along Doffing Avenue and River Road, could experience flood damage,

The predicted crest on Monday is likely to be the first of several tests that the levee, homeowners and city officials will have to endure: City Engineer Tom Kaldunski and City Administrator Joe Lynch believe the river may crest not once, but several times over the next few weeks.

“We anticipate that it will increase over time and it may stay elevated for probably up to two or three weeks,” Lynch said on Wednesday.

The top of the levee sits at an elevation of 702 to 704 feet above sea level, according to a survey completed by city staff. In the event that flood predictions call for a “100-year flood event,” Kaldunski said, city staff would dump fill on top of a 500-600-foot portion of levee to bring its elevation up to a uniform 704 feet above sea level. On Tuesday, Kaldunski said the river's elevation stood at 690 feet above sea level.

If a 100-year flooding event occurs, Kaldunski said, the waters would reach an elevation of roughly 702 feet above sea level, leaving a two-foot margin between the top of the dike and the river flow. But Lynch and Kaldunski have expressed concerns about the integrity of the levee itself.

Built as a temporary emergency levee, the dike has not been properly maintained over the years, Lynch said. Trees and plant growth on the dike could potentially disrupt the soil in the levee, creating weak points or cracks that water could push through.

“If it were a permanent levy and it was constantly maintained, we’d be more sure. It’s not as structurally sound as it should be,” Lynch said. “Do we think it’s going to fail? No. Are we planning in case it does? Yes.”

The city has posted links to flood-related information and resources on its website. The city may close portions of River Road south of 66th Street, and will likely barricade 64th, 65th and 66th Streets to keep the public away from potentially dangerous floodwater.