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Water Purification

Water drawn from Lake Springfield for the purpose of meeting the greater Springfield area’s domestic water needs is purified at the CWLP Water Purification Plant, located just north of the Dallman and Unit 4 electric generating stations. The Water Purification Plant first opened in 1935 with completion of Lake Springfield and since has undergone several expansions and upgrades to improve systems and processes over the decades. The most recent upgrades and expansions, representing the water system’s largest overhaul since construction of the lakeside operation, included new construction of the high service and low service pump stations, which increased capacity, redundancy and performance. Completion of these pump stations in 2014 brought the Water Purification Plant it to its current capacity to pump lake water to the plant from 44 million to 52 million gallons a day and to pump finished water to the utility’s distribution system from 46 million to 60 million gallons per day.

Upgrades and replacements of a number of other systems, including construction of a new clearwell, clarifier, filters, chemical storage facilities, dam gates and more, were part of these projects all geared to modernize systems, expand capability, capacity and safety of water operations. The current infrastructure improvement program, with bonding covered by water rate increases phased in from 2008 to 2011, helps ensure safe and reliable water operations for CWLP customers for generations to come.


Purification Process Read More   

Steps taken during the water purification process ensure CWLP's ability to convert raw lake water into a safe, clean product that consistently meets state water quality standards.

The purification process begins at the intake tower, where water flows into one of the tower's four gates, passes through a six-foot tunnel, and enters the low-service pump station on the northwest shore of Lake Springfield. There, revolving screens remove fish, leaves and other large debris. It is also at this point that powdered activated carbon is added to remove unpleasant tastes and odors, as well as residual agricultural pesticides.

The water is then pumped to the Purification Plant, where it passes through a chemical dosing chamber to receive lime, which softens the water, and ferric sulfate (iron) and polymer, both of which coagulate the suspended particles in the water. From the dosing chamber, the water passes to one of five upflow clarifiers.

In the clarifiers, 90% of the suspended particles are removed from the water, which is then sent to the filter gallery for the final step in the purification process. On its way to the filter gallery, the clarified water receives a dose of carbon dioxide to lower the pH (which was raised during the lime softening process), chlorine to kill bacteria, and fluoride to prevent tooth decay.

From the filter gallery, the clean water is sent to two clearwells on the plant grounds for temporary storage prior to distribution (via the utility's new high-service pump station that was completed in spring 2014). At this point, the purification process is complete. It has taken less than two hours to convert raw lake water into a safe, clean product that consistently meets state water quality standards.

Clarification & Filtration Read More   

CWLP has a total of five clarifiers, which have represented three different technologies at the lakeside site at different times. Two of these technologies, designed by CWLP Water Superintendents, have led the industry over the years in clarification use across the world.

The newest clarifiers are Helical Flow Clarifiers or ClariCone®, and were designed by former CWLP Water Plant Superintendent, Dave Wyness. In this type of clarifier, the water is introduced into the base of the clarifier where it moves upward in an ever expanding and slowing spiral motion, passing through the lime sludge blanket on its way to the filter gallery for the final stage of purification. The Helical Flow Clarifier is superior to its preceding design as it has no moving parts and requires no power to operate. Second, it is better at removing suspended particles, producing a better overall water quality.

These Helical Flow Clarifiers were rebuilt in the footprint of the plants original clarifiers, Spaulding Upflow. The Spaulding clarifiers were designed by the utility's first Water Plant Superintendent, Charles Spaulding and placed into operation when the lakeside Water Purification Plant was built in 1935. This original clarifier technology became an industry standard and is still used by purification plants around the world. CWLP’s last Spaulding clarifier was retired and rebuilt as a Helical Flow in 2014.

The second type of clarifier currently being used by CWLP is a Permutit unit, which is simply a modified version of the Spaulding clarifier. CWLP currently has two Permutit-style clarifiers, which were built in the mid-1950s.

Water that leaves the clarifiers, moves to the filters for the next step in the process. Each of the filters in the filter gallery contains a layer each of sand and finely crushed anthracite coal, which screen out additional particles still remaining in the water. These filters are cleaned about every 96 hours by "backwashing" them with 60,000 gallons of water per filter. A current project underway will add four new filters to the plant in summer of 2021.

From the filter gallery, the clean water is sent to two underground clearwells for temporary storage prior to distribution.

Water Filter Expansion Project Read More   

The Water Filter Expansion project, ($15M) at the Water Purification Plant added four new filters. Construction began in July of 2019 and was completed in 2022. These filters work in addition to the 12 in operation, which represent the final step in the water treatment process. It is here where the smallest particles from the water are removed before going to the clearwells and out the high service pump station to the distribution system to customers.

Each of the filters in the filter gallery contains a layer each of sand and finely crushed anthracite coal, which screen out additional particles still remaining in the water. These filters are cleaned about every 96 hours by "backwashing" them with 60,000 gallons of water per filter.

Completion of this project brings CWLP treatment capacity from 46 million gallons per day to approximately 57 million gallons per day. Increasing capacity improves the operation of the filters by decreasing the overall flow rate. The goal of the project is to decrease this loading rate on the existing filters to allow filtration to be more effective.

Building New Clearwell Read More   

A new $8.3 million, six-million gallon underground clearwell was put into service in May 2014. The clearwell provides on-site water storage, holding treated drinking water for a several hours before it is distributed throughout the city for use by consumers. The holding period allows time for chlorine added to the water during the purification process to complete its work disinfecting the water of bacteria and other potential pathogens that might have been present in the raw water supply.

Completion of the new clearwell, as well as a new high-service pump station, allowed the utility to remove from service the oldest of its two existing underground clearwells, which were built in the mid-1930s. Once the new clearwell—which acts in tandem with the remaining existing underground 1950s clearwell—was placed in operation, the utility's total clearwell capacity increased from six million gallons to 10 million gallons. The new clearwell's interior consists of a series of "baffle" walls that direct the flow of water through it. This ensures the chlorine added to the water during the purification process has adequate time to disinfect the water.

Building New Pump Stations Read More   

Construction of two new water pumping stations ($40M), a high-service and a low-service pump station, were completed in 2014. This project increased the capacity, redundancy and performance of water plant operations and increased pump capacity in both systems. These facilities were previously located in the Lakeside Power Station where they operated since that facility’s inception in 1935.



The new low-service pump station, which was completed in the fall of September 2014, pumps raw water from the lake to the Purification Plant and increased the utility’s capacity to pump lake water to the plant from 44 million to 52 million gallons a day. This pump station is located on the northwest shore of the lake near the Spaulding Dam.



The high-service pump station, which was completed in May 2014, pumps water from the clearwell into the city-wide water distribution system and increased the utility’s firm capacity to pump finished water to the distribution system from 46 million to 60 million gallons a day. This pump station is located south of the new clearwell.