RIVER: PUMPS RID DOWNTOWN OF WATER

Although the floodwall and a levee in downtown Cape Girardeau hold back the Mississippi River, the Merriwether and Mill street pumping stations keep downtown dry during wet weather when the river floods.

When the river is below 30 feet on the Cape Girardeau gauge, the pumping stations are closed and stormwater flows directly from storm sewers to tunnels under the levee and floodwall. When the river is above flood stage, as it now is and is forecast to continue to rise, the Main Street and North Main Street levee districts put the pumps on line.

The Merriwether pumping station is owned and operated by the Main Street Levee District. The Mill Street pumping station is owned by the North Main Street Levee District and is operated by employees of Union Electric Co., a large property owner in the district.

The Merriwether station was completed in 1958; the Mill Street station about two years later.

C.A. "Andy" Juden Jr. president of the Main Street district, said the Merriwether station is the larger of the two pumping stations because of the area it serves. He said the station receives stormwater and some sanitary sewage in an area bounded on the south by Good Hope, on the west by Pacific, and on the north by Bellevue.

"About 90 percent of the stormwater that falls in this area comes into the pump station through the Merriwether Street sewer line," said Juden. "The rest of the water flows into pressurized sewer mains and is forced into the river by water pressure and gravity. Because most of the area has a lot of concrete and blacktop streets and sidewalks, there is a large amount of runoff into the storm sewers that drain into the pump station."

Juden said the stormwater enters the pumping station through the Merriwether Street storm and sanitary sewer line, which is about 20 feet below the ground's surface. The sewer line enters a 20-foot-deep concrete sump well that extends along the north side and beneath the floor of the station.

During dry weather surface water and sewage drains into the sump well and20is pumped out about every six hours by two submerged pumps at the bottom of the wells.

The two smaller pumps force the water in the sump well and into a concrete reservoir that's built onto a wall of the pump station. Since the water level in the reservoir is the same level as the river, any additional water pumped into the reservoir forces water already in the reservoir through a 7-by-7-foot tunnel under the floodwall.

When heavy rain occurs downtown, one or more of the three, 36-inch, 200-horsepower electric pumps above the sump well can be started. Each can pump up to 20,000 gallons per minute. Each pump operates on 440 volts and draws 250 amperes of current. Together, the three large pumps and two smaller ones have a pumping capacity of 75,000 gallons per minute.

Juden said the last time all five pumps were in operation at the same time was in May 1973, when the river neared its all-time record flood crest of 45.6 feet. At the same time, thunderstorms dumped up to 8 inches of water in a matter of hours over the city.

"We had all five pumps working that night," said Juden. "The water was coming down so fast that it was pooling on Main Street because it couldn't get into the pump station fast enough to be pumped out into the river."

During a cloudburst Monday night, two of the large pumps were operated for about five minutes each to handle the water that flowed into the pump station, said Juden.

Juden said Union Electric has assigned a high priority to the pump station in case of a power outage. "In a heavy rain of 1 inches or more an hour, I have about 10 minutes after the power goes off before there's water over Main Street," said Juden. "That's my bad dream."

The pumping station has been without power only two times since it opened in 1958, he said. The most recent was about two weeks ago when an automobile accident caused a power blackout. Juden said the river was still low enough that water going into the pumping station could be forced under the floodwall by gravity flow.

Although the smaller pumps operate automatically as the sump well fills, the larger pumps must be put on line manually by the pumping station operator. The station is manned 24-hours a day when it is in operation.

Juden recalled an incident several years ago when the pumping station started receiving an extra 40,000-gallon flow per minute on a bright, sunny day. The operator quickly put one of the large pumps on line to handle the extra flow.

"It took about two hours to figure out what happened," said Juden. "We thought a water main had broken, but a sewer up in Happy Hollow (between Lorimier and South Frederick) had been accidentally cut. There were four acres of water 7 feet deep in Happy Hollow. All of that water was draining into the pump station," he said.

Juden said that when the station opened it only operated during the spring flood season. Since the record 1973 flood, however, the station has been in operation at different times of the year because flooding on the river occurs more often.

Juden said: "We've had the station working on Christmas Day. We've pumped every month of the year at one time or another during the past 25-30 years. In 1973, we pumped over 200 days. So far this year the pump station has been open 82 days."

The stations are operated with revenue from a tax on commercial property owners in each levee district.