Columbia seeks voter approval to improve water distribution system

On Nov. 4, Columbia voters will decide whether to approve a $39 million bond that would fund improvements to the city’s water system. Rate payers would pay off the debt in six years, and the city estimates their bills would increase 1.5 percent in the first two years and 5 percent in the final four years.

From creek water to alluvial aquifer

A few old-timers may know that before the city purchased the Columbia Water and Light Company, tap water came from a reservoir formed by damming Hinkson Creek near the present intersection of East Broadway and U.S. 63. That’s right, creek water, along with some shallow wells inside the city.

After voters approved the purchase of the private company in 1904, Columbia began using “deep wells” that tapped into groundwater within the city limits. Although those wells are still ready in case of an emergency, Columbia opened its water treatment plant in McBaine in 1972 to meet fast-growing demand.

Now, all of the city’s tap water and fire-fighting water comes from 15 wells dug in the floodplain between McBaine and the Missouri River. The wells tap into an alluvial aquifer, an underground rock deposit saturated with water. Water slowly moves through the rock, which naturally filters it. There is an estimated 44 billion gallons of water within the aquifer, and groundwater is constantly replenished.

The wells, averaging 110 feet deep, pump the water to the treatment plant in McBaine, which oxidizes, softens and filters the water before pumping it about 10 miles, some 200 feet uphill, to the city’s two operating pump stations, one at Ash and Bernadette and the other at Nifong and Bethel.

With the ability to pump about 32 million gallons of water per day, the treatment plant averaged 14.3 million gallons per day in 2007. After being pumped partially into the city, the pump stations help distribute the water throughout the city and, along with the city’s three water towers, store water reserves to handle higher water demand, particularly during the summer, and firefighting.

But it’s been five years since the last upgrade, and the water distribution system is beginning to show its age, with more frequent main breaks and concerns about water quality.

Paying for pressure

Usually the Water and Light Department asks voters to approve bonds to pay for system improvements every five years. The last water bond, in 2003, primarily financed improvements to the water treatment plant and a new pump station on Hillsdale road that should be in operation by the end of this year.

More than half of the money from the proposed bond this year will go toward upgrading the distribution system. That means increasing the size of some water mains and building new water mains. The city also wants to replace old mains and increase the flow of water throughout the city through a process the Water and Light Department calls, “closing loops.” Some water mains that service certain areas of the city just stop; that is, they aren’t connected back into the rest of the system to create a constant flow.

Many of the projects on the bond list are designated to reconnect these dead end pipes with other pipes, keeping the water flowing rather than just sitting at the end of a main, sometimes for several days.

The rest of the money will go toward annual maintenance, firefighting supply and water production. Water production, which entails adding and upgrading equipment at the pump stations and treatment plant, also means the city will drill three new wells into the aquifer, increasing the total to 18.

City addresses drinking water quality

During the regular testing of Columbia’s drinking water, state regulators found that the levels of a chemical compound called trihalomethane slightly exceeded maximum levels set by the Environmental Protection Agency. Trihalomethanes are cancer-causing compounds formed when organic material interacts over time with chlorine, which the city uses to disinfect the water.

A test that came from two monitoring wells, located near the wetlands, used to treat wastewater found higher than normal chloride levels, which can indicate the presence of wastewater.

There were concerns that the proximity of the wells and the wetlands might be causing the increased trihalomethane levels. But tests conducted by University of Missouri scientists showed wells nearest the wetlands did not have a significantly higher trihalomethane level than the others. Water and Light decided to conduct a long range study to find how to best address the problem at the treatment plant.

For now, the department is considering adding ammonia to the water at the treatment plant. Ammonia slows the formation of trihalomethanes and is inexpensive and easy to implement, but the decision is subject to the Department of Natural Resources and City Council approval.

In addition, the water distribution projects proposed for the bond issue would increase flow throughout the system. Although it varies, the average amount of time water is in the pipes between when it is treated and when it comes out of the faucet is three days. Increasing the flow, especially reconnecting the dead-end pipes, will reduce the amount of time water stays in the pipes and make it less likely that trihalomethanes will have time to form in the city’s water system.

Water bond by the numbers:

Increased distribution system flow: $20,157,200
Water main replacements: $2,735,000
Fire flow: $1,614,500
School fire flow: $1,307,800
Annual maintenance: $9,300,000
Water production projects: $2,725,000
Contingency fund (will be used to cover possible ammonia treatment): $600,000
Bond financing costs: $500,500