Raw Water Supply
Raw water for the system is obtained from Lake Michigan. Water is drawn from an inlet structure 3,000 feet offshore and is directed to a raw water pump station through a 54-inch diameter steel intake pipe. A treatment to discourage zebra mussel attachment is introduced at the inlet structure and removal of algae and large debris is screened from the water at the pump station. Raw water pumps lift the water 110 feet and convey the raw water approximately two miles through a 48-inch pipeline to the water treatment facility.

Water Treatment Facility
Located on 27 acres in Lake Bluff, the Paul M. Neal Water Treatment Facility serves as the headquarters for CLCJAWA administration, operations, maintenance, and laboratory staff, as well as the water treatment processes.

The treatment facility, arranged in four parallel 12.5-mgd processing trains, is entirely enclosed to allow for ease of operation and maintenance in all weather conditions. The facility originally included three processing trains for a total capacity of 37.5 mgd, but was expanded in 1999 to add a fourth train, increasing the treatment capacity to 50 mgd.

Innovative treatment processes allow the facility to meet the most stringent drinking water regulations. CLCJAWA is on the forefront of treatment technology implementing treatment processes to provide water quality that exceeds EPA regulatory requirements. CLCJAWA is the first plant in Illinois to introduce processes such as ozonation, inclined plate sedimentation, granular activated carbon filtration and ultraviolet light treatment. CLCJAWA is meeting its goal of providing high-quality water to its members.


Pre-Disinfection
The first treatment process encountered in the plant is ozonation. As one of the most powerful oxidants available, ozone provides many benefits such as disinfection, taste and odor control, and enhancement of particulate removal.
Due to its high reactivity, ozone must be generated onsite. Ambient air is compressed, dried, and filtered in a series of air preparation steps. Next, ozone is generated by applying electricity to the air stream. The resulting ozone and air mixture is immediately diffused into the water, where it lasts for less than 20 minutes.

Rapid Mix/Flocculation
After ozonation, the water enters the rapid mix basins where a coagulant is added to facilitate the removal of suspended particulate matter. The rapid mix basins provide quick and uniform dispersion of the coagulant. Coagulants react with particulates in the raw water to enhance their ability to bind together.

Following the rapid mix basins, the water is gently stirred in a three-stage flocculation process. As the water slowly travels through the flocculation basins, the particulate matter continually collides and sticks together into progressively larger particles called floc. The multi-staged basins along with variable speed mixers allow for optimized treatment as water quality, flow rate and temperature vary.

Sedimentation
Following flocculation, the floc particles are large and heavy enough to settle within the sedimentation basins. The sedimentation basins are equipped with a series of parallel inclined plates to enhance the settling process. As an innovative technology, the use of inclined plates substantially reduces the basin surface area requirements, accomplishing equivalent solids removal in a much smaller floor area than in a conventional sedimentation process.

In the sedimentation basin, as the flocculated water travels upward between the plates, the heavy floc particles naturally fall by gravity. Once a floc particle lands on a plate surface, it slides down the plate to the bottom of the basin for removal. From there, the solids are sent to the residual solids processing facility.

Filtration
Fine particulate matter that escapes the sedimentation process is removed by the filtration process. In addition to trapping solids, the filters provide the capacity to remove dissolved organic compounds through the process of biological degradation.

The plant is equipped with 12 filters, each consisting of a large concrete box containing four feet of biologically active carbon over sand and gravel. Water quality is continuously monitored to meet turbidity standards.

The filters must be periodically backwashed, or cleaned, by reversing the direction of water. During the backwash cycle, compressed air followed by clean water is forced backwards through the filter bed, thereby removing the particles that have been trapped in the media. The backwash water with the removed particles is sent to the residual solids processing facility.

Ultraviolet Disinfection
Following the filtration process, filtered water is subjected to ultraviolet light. The ultraviolet light process, added in 2005, inactivates bacteria in the filtered water without the use of any chemicals. From the ultraviolet reactors, the filtered water proceeds to the finished water clearwells.

Residuals Solids Treatment Building
The silt, sand and other materials present in Lake Michigan waters are removed during the treatment process. These “residual solids” from the settling tanks and filters are concentrated at the Residual Solids Processing Building for ultimate disposal at a landfill. Several steps are employed to concentrate these solids.

Solids collected at the bottom of the sedimentation basin and in the backwash water are concentrated in two gravity thickeners. Thickener “decant” is recycled to the head of the plant for pre-treatment.

The concentrated solids in the thickeners are pumped into the dewatering centrifuges. These centrifuges rotate at high speeds where more than 90% of the water is removed from the thickened sludge producing a solid, non-hazardous material that is hauled from the plant for disposal in a landfill.


Power Generation Facilities
As part of CLCJAWA’s goal of providing safe and reliable drinking water to its member communities, the plant includes a combination of two diesel and three natural gas powered engine generators.

The generators produce electrical power to run the water plant in the event of a power outage from the electric power utility. This assures that electricity will be available to treat and to supply water at all times. Having the capability to generate its own power also helps CLCJAWA produce drinking water more cost-effectively.