Construction has begun on a $600,000 project to improve the reliability of the city’s Kaw Water Treatment plant, and planning is under way for a $7 million project that will involve trying to figure out the shifting sands of the Kansas River.

The city has shut down the Kaw Water Treatment Plant, Third and Indiana streets, for the month of March while crews replace several critical valves that are more than 50 years old.

“Because of their age, the valves don’t close all the way,” said Jeanette Klamm, a programs manager with the city’s Utilities Department. “If we ever had to isolate the plant for some reason, we couldn’t do that without some people who live near the plant being out of water.”

Crews are installing 36-inch valves and new piping in the front yard area of the plant. During the project, all of the city’s water is being supplied by the Clinton Water Treatment Plant in West Lawrence.

During the project, traffic on portions of Third and Indiana streets may be affected. The city’s bulk water station, where customers can pay to fill large, portable tanks, is closed for the month. The project is expected to be completed in early April.

But there is plenty of additional water plant work that will stretch throughout 2012 and into 2013. Utilities Director Dave Wagner said the city has begun working with Black & Veatch engineers to design a solution to a malfunctioning Kansas River intake that forced city officials to essentially shut down the plant several times over the last year.

Figuring out a solution for that problem will be complicated because it involves trying to predict how the sands of the Kansas River will settle.

“It is going to be a pretty significant effort,” Wagner said.

The Kaw River plant is designed to operate with two intake pipes in the Kansas River. One of the intakes has long been inoperable, and over the last several years sand has periodically clogged the lone remaining intake.

The city’s utility rate plan has about $7 million in its budget to build a new intake and hopefully improve the existing intake to the point that it can be used as a backup.

But first, engineers have to better understand the shifting sands of the Kansas River. That can be difficult enough in ordinary times, but Wagner said the construction of the new Kansas Turnpike bridges upstream of the plant have changed the dynamics of the river.

Following the construction of the bridges, for example, a large sandbar has emerged near Kansas University’s boathouse in Burcham Park.

“It is there now,” Wagner said. “Whether it stays there or not is one of the things we’ll try to figure out.”

The sandbar, though, is one of the few changes visible to the naked eye. Equally significant changes are happening on the bottom of the river. Wagner said contractors for Black & Veatch will be on boats in the river using electronic equipment to map the bottom of the river and measuring the velocity of the river’s flow.

In addition, engineers will have to predict the impact changes to the Bowersock Dam, which is just downstream of the plant, will have on the river. Plans call for an inflatable “rubber dam” to be installed on top of the existing dam. That will allow for higher water levels upstream of the dam, which will change the river’s sedimentation pattern.

Understanding the changing sedimentation patterns of the river will be important in determining what type of improvements are needed to make the river intakes work properly, Wagner said.

Wagner said he expects to start getting results from the study in the fall, but construction on a new intake likely would not begin until 2013.

Wagner said if problems with the intake do cause the Kaw plant to be shut down again, the city’s Clinton Water Treatment Plant is in a good position to serve the entire city.

“The Clinton plant can keep up with high demand,” Wagner said. “But it can’t keep up with a super summer peak that happens maybe once every five or 10 years.

“We feel like we have the Kaw intake reliable and cleaned out, but it is not in the condition we would like to operate under.”