Iowa DNR News
Environmental Services Division
For immediate release June 22, 2007
HEAVY STORMS IN SOUTHEAST IOWA CAUSE NUMEROUS WASTEWATER BYPASSES
MEDIA CONTACT: Paul Brandt at 319-653-2135
WASHINGTON – Heavy rain caused several cities in Southeast Iowa to discharge
wastewater Friday morning.
The following cities reported bypasses to the DNR Friday morning:
Cedar County
West Branch: The City of West Branch reported discharging untreated
wastewater after heavy rain inundated the local treatment facility. The
wastewater began bypassing to a nearby farm field at a rate of 30,000
gallons per hour around 7:15 a.m. Friday morning. The discharge was finished
by 11:00 a.m. Friday morning.
Des Moines County
Burlington: The City of Burlington’s four sanitary sewers were overflowing
due to heavy rain accumulation in the area. Approximately 624,000 gallons
of wastewater were bypassed from the location of Brooks, Gunnison,
Burlington Northern and Lucas sanitary sewers. The 8-hour discharge began
around 1:00 a.m. Friday morning and was finished by 9:00 a.m.
Johnson County
Coralville: One of Coralville’s lift stations is recovering after pumping
wastewater to Clear Creek Friday morning. With over five inches of rain
falling in the area, a pump was placed at the 3rd street lift station in
order to keep up with the flow. From 6:00 – 6:30 a.m., the pump discharged
sewage to the creek. DNR and University of Iowa Water Plant officials were
notified of the occurrence.
Iowa City: Cornstalks, rainwater and sewage from a privately owned treatment
system are causing
Snyder Creek in Iowa City to back up. With over six inches of rain
accumulation, Sunrise Village Mobile Home Park’s third sewage treatment
lagoon is overflowing to the creek. An undisclosed amount of
partially-treated wastewater reached the creek Friday morning. Cornstalks
from nearby fields are causing the creek to back up. By 9:15 a.m. Friday
morning, the lagoon had stopped overflowing. Clean-up of the cornstalks was
underway to ensure
Lone Tree: Sanitary Sewers are swelling to capacity in the City of Lone Tree
as storm water continues to accumulate. At 7:45 a.m. Friday morning, the
City began bypassing wastewater to a local ditch in order to protect its
sewers and residents. Localized flooding in Johnson County is apparent, with
a rain gauge in the community reporting more than 3.5 inches of rain falling
Friday morning alone. DNR staff anticipates the bypass will continue until
the storm system passes the area.
Muscatine County
West Liberty: The City of West Liberty reported bypassing wastewater Friday
morning at 2:30 a.m. after 6 inches of rain overwhelmed the treatment plant.
Between 7:30-8:00 a.m. Friday morning, the plant bypassed wastewater to a
ditch that flows to the Wapsinonoc Creek in order to prevent residents’
basement flooding.
Wapello County
Wapello: A lift station was reported discharging in the City of Wapello
after lightning struck it sometime Friday night. The combined sewer overflow
was reported to DNR staff around 9:00 a.m. this morning. Alliant Energy had
power was restored to the lift station by 10:50 a.m. Friday.
Washington County
Washington: The City of Washington reported discharging wastewater to a
nearby farm field after rainfall totals overwhelmed its treatment facility.
The bypass started 9:30 a.m. Friday morning at a rate of 15,000 gallons per
hour. The bypass was completed by 10:10 a.m. Friday, however untreated
effluent was still being forced out of the system because of high flows.
Bypasses can occur when heavy rain overloads wastewater collection systems,
which are the underground pipes that carry sewage to a treatment plant. When
sewer pipes are overwhelmed, the excess rainwater and sewage have nowhere to
go. Cities bypass to lower the wastewater level in the collection system and
prevent backups into basements through floor drains. Although discharging
wastewater to a stream is not desirable, it does prevent a greater and more
immediate health risk in people’s homes.
Collection systems are most likely to be overwhelmed when heavy rainfalls or
excess snow melts, saturates the ground and enters a sanitary sewer system
through cracks in the underground sewer pipes.
Storm water can also enter piping through improper connections, such as roof
drains or sump pumps that are hooked up to the sanitary sewer system instead
of the storm water system. If the storm water entered the storm sewer
system, it would flow directly into a nearby stream or lake. When it enters
the sanitary sewer system it flows to a wastewater treatment system. When
heavy rains or snowmelt occurs, the volume of storm water entering the
sanitary sewer system can be more than the wastewater treatment system can
treat.
According to DNR design standards for construction of new wastewater
treatment systems, facilities should be able to handle the amount of water
in the collection system from all three of these events happening at the
same time:
§ Peak sewage flows from homes, businesses and industry
§ Peak groundwater levels
§ A storm that drops two inches of water in an hour.
While many collection systems in Iowa already have or are in the process of
upgrading their collection systems to handle these events, many more need to
upgrade.
The DNR tracks bypass reports submitted by facilities and follows up with
the facility to determine problems and help them upgrade their systems,
although it can be a long-term process. The DNR has also formed a committee
to discuss how it handles wet weather bypasses.
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