Water intake structures located on shores of the Kansas River at the Topeka Water Treatment Facility. Picture shows elevated turbidity levels caused by recent rains. The Operations Section at the Topeka Water Treatment Facility uses various chemical and mechanical processes to transform raw water from the Kansas River into clean and safe drinking water. The first of these treatment processes is the elevation of raw river water into the treatment basins using water intake structures. The Topeka Water Treatment Facility has two intake structures that contain six pumps each. All water intake pumps have rated daily capacities of five to ten million gallons. A durable and heavyweight, small mesh traveling screen is positioned immediate the intake pumps to prevent entry of debris that may either damage mechanical equipment or impair chemical treatment processes.

Picture shows the South Plant (1954). The newest plant, the East-South Plant (1999), was constructed in parallel and identical design as the East-North Plant (1981). Many infrastructure improvements were added in 1999 to 2001.

At the Topeka Water Treatment Facility, there are many shapes and sizes of basins and each is designed to provide controlled contact and settling time for each specific chemical or mechanical process. Depending on their location in the treatment scheme, individual basin capacities range from thousands of gallons to nearly three million gallons. The basins in each of the three treatment plants at the Topeka Water Treatment Facility are connected in series, with each adjoining basin slightly lower in elevation than the previous. This allows the water to continuously flow by gravity from the beginning of the treatment process to the end. The average detention time for an entire process cycle though each of the three treatment plants is nearly 24 hours.

Empty sedimentation basin shows large sweeps and blow-down structures used to collect and dispel settled solids.

The first chemical used in the water treatment process at the Topeka Water Treatment Facility is a positively charged synthetic polymer. It is flash-mixed into the raw river water before it flows into the first sedimentation basin. The polymer effectively attracts and enmeshes negatively charged turbidity particles in raw river water and causes them to settle. A large blow-down located at the center of the polymer sedimentation basin is activated at timed intervals to dispel settled and collected solids. This process reduces the amount of suspended material or turbidity significantly.

View of disinfection contact basin roof. Interior partitions and baffles provide controlled chemical application.

The partially processed water then flows by gravity to the disinfection contact basin. Chlorine is added at the disinfection contact basin to destroy any bacteria or viruses that may be present. Ammonia is subsequently added at a specified entry point after chlorine addition to form the secondary distribution disinfectant, chloramine. A series of baffles in the disinfection contact basin provide effective contact and reaction time to ensure that the destruction of pathogens is complete. The controlled application of chlorine and ammonia in the absence of sunlight reduces the level of disinfection by-products below regulatory requirements. These small, covered and baffled treatment units are also designed to be economically and easily retrofit as regulations progress and alternative disinfectants such as chlorine dioxide and ozone are required.

Center ring of basin shows a mixture of lime and dissolved minerals coming out of solution. Precipitated water hardness minerals are removed with blow-downs.

The disinfected water then flows into the coagulation, flocculation and softening basins where lime and alum are added. Lime reacts with various dissolved minerals to form primarily two insoluble precipitates: calcium carbonate and magnesium hydroxide. Additionally, the softening process enmeshes, coagulates and settles smaller remaining particles and dissolved organic substances. Alum is added to further aid and enhance coagulation. In the two east treatment plants, previously reacted solids in specialized solid contact basins provide improved softening precipitation and efficiency of chemical application.

View of the previous basin shown when empty to illustrate solids contact structure. Clarification basins have similar collection weirs, sweeps and blow-downs.

The water is then diverted to large primary clarification basins that allow additional detention time for gravity to settle out remaining precipitates and suspended materials. Large sweeps slowly rotate along the entire bottom of these basins to collect and move settled precipitates and turbidity to a central collection area. Large blow-downs located at the center of the primary clarification basins are activated at timed intervals to dispel settled and collected solids.

The collection of water in weirs on the clarification basin after additional detention time has allowed more suspended particles to settle.

After the primary clarification basin, carbon dioxide is bubbled in to stabilize and lower the pH of softened water. Controlled application of soda ash and phosphate is also added at the primary recarbonation basin to increase the alkalinity level and provide corrosion control. The water then flows into a second large clarification basin. This allows additional detention time for remaining suspensions and precipitates to settle. Center sweeps and blow-downs collect and remove additional settled solids. After water exits the secondary clarifying basin, fluoride is added to supplement levels that occur naturally.

The picture shows a series of East Plant filtration consoles. Large rectangular filtration beds are located in the enclosed area behind the doors.

Cleansing of the water through specialized filtration units completes the treatment process at the Topeka Water Treatment Facility. The small amounts of suspended fine particles that remain after secondary clarification are nearly all removed by processing the water through automated filtration units. The Topeka Water Treatment Facility has nearly 10,000 square feet of mixed layer filtration units containing approximately four feet of filtrating materials. Regular cleaning of the filter beds is accomplished by repeatedly forcing clean water up through filtration beds. Processed filtered water is stored in clearwell reservoirs located beneath the filters. To ensure the filtration process is optimized, turbidity meters continuously monitor finished water quality.

The Topeka Water Treatment Facility uses only turbine pumps to elevate water. The suction shafts on these pumps are as long as twenty-seven feet.

The Topeka Water Treatment Facility has nearly nine million gallons of underground reservoir storage and seven high service pumps with rated capacities from five to fifteen million gallons a day.

These pumps transfer water from underground clearwells into four large transmission lines.

These large arterial water lines branch out into a network of more than 800 miles of water mains that transport clean and safe drinking water every day.