Posts Tagged ‘flood improvements’January 16, 2012
Water Day at the Iowa State Capitol is January 17, 2012, and Des Moines Water Works will be there on behalf of the approximately 500,000 people in DMWW’s service area.
Every Year, DMWW sees Water Day as an opportunity to talk with legislators from Central Iowa and across the state about improving and protecting water resources in the Raccoon and Des Moines Rivers, the sources of water for DMWW drinking water. Reducing nutrients, bacteria, and algae blooms in our source waters helps protect public health and contain the cost of treating drinking water for our customers.
This is also an opportunity to discuss protecting the utility’s $352 million of infrastructure from flood events – infrastructure owned by the citizens of Des Moines. In 1993, the Fleur Drive Treatment Plant was flooded and DMWW was not able to provide drinking water to customers for approximately 10-14 days. Since 2008, more than 65-feet of river bank have been lost at the L.D. McMullen Treatment Plant well field site, putting several wells at risk for damage. More frequent (and intense) rainfall events and expeditious movement of water off the landscape through tiling, have exacerbated flooding. The connectivity of surface water, ground water and soils exist on all levels and need to be managed as a system. The power of moving water, whether a raindrop or a torrent of flood water, can be better managed in Iowa.
Water is the vital resource to support all forms of life. Unfortunately, water is not evenly distributed by location or by the season of the year. Some areas of the country are more arid and water is a scarce and precious commodity. Other areas of the country receive more than adequate amounts of rain causing occasional floods and loss of life and property. Throughout history, dams and reservoirs have been constructed to collect, store and manage the supply of water to sustain civilization.
The primary benefit of dams and reservoirs is water supply. Reservoirs also provide benefits such as flood control, recreation, scenic beauty, fish and wildlife habitat and, at some dams, hydro-electric power. Currently there are about 45,000 dams higher than 50 feet throughout the world. While some are more than 2,000 years old, over 70% have been built in the last 50 years.
The Maffitt Dam was constructed by Des Moines Water Works (DMWW) as an emergency water supply. Construction started in August 1943 and the dam was completed in March 1945. Water was pumped from the Raccoon River to fill the reservoir. Maffitt Reservoir stores 1.57 billion gallons of water. The original plan was to store water in the reservoir that could be released during periods of low flow in the Raccoon River. The current plan is to use water from the reservoir as an emergency raw water source for the L.D. McMullen Water Treatment Plant.
In May of 1982, DMWW entered into a contract with the State of Iowa to purchase storage capacity in the Saylorville Reservoir. DMWW paid a portion of the Saylorville Reservoir construction costs and makes annual payments for a portion of the operational costs. These payments give DMMW access to 3.2 billion gallons of Saylorville Reservoir water that can be utilized in a drought situation.
Between the Maffitt and Saylorville Reservoirs, DMWW has access to 4.77 billion gallons of water to meet the water needs of our customers in the event of an emergency or drought situation.
The Raccoon River was above flood stage in Water Works Park seven times in 2010. Even though record high flood levels were not reached, all that water creates a lot of work and makes us wonder what the future will bring.
In 1993 the levee surrounding Water Works’ Fleur Drive Treatment Plant was overtopped by flood waters, leaving the Des Moines without water for more than a week. Since then a number of projects have been completed to help ensure this does not happen again.
Most importantly, the levee surrounding the Fleur Drive Plant has been raised by six feet to a level four feet above the record 1993 water level. A flood gate has also been added which can be closed quickly as compared to the earthen plug that was used to close the levee in the past. These improvements have not seen water as high as 1993 but they were tested during the flooding in 2008 when more than 8 feet of water rose against the 14-foot tall flood gates. The levee and flood gates performed well and treatment plant facilities were protected.
In addition to levee and flood gate improvements the Water Works has added additional sources of supply since 1993. In 2000 the LD McMullen Water Treatment Facility went into service near Maffitt Reservoir with the ability to produce up 25 million gallons of water per day. Four aquifer storage and recovery wells have also been constructed around the metro with a combined capacity of over 10 million gallons per day. Later this year the new Saylorville Water Treatment Plant will go on line with the capacity to supply up to an additional 10 million gallons per day to the metro area. Taken together these facilities provide valuable backup to the primary Fleur Drive Water Treatment Plant.
All of these changes have helped protect the water supply but Water Works Park is still vulnerable to flooding. Just this year the high water has caused tens of thousands of dollars of damage to park roads, plantings, and other park facilities. Each time the water level goes above flood stage the cleanup effort in the park requires hundreds of man hours to complete. In addition high water resulted in the cancellation or relocation of numerous events scheduled on park grounds including concerts, cultural festivals, and family gatherings.