KAI Design & Build Completes One of Country's Largest UV Wastewater Disinfection Systems
System required 3,600 UV bulbs and 6,500 cubic yards of concrete

(ST. LOUIS, MO, Dec. 17, 2013) - Six hundred and nine days in the making, KAI Design & Build recently completed a construction management assignment to build one of the largest Ultraviolet (UV) wastewater disinfection systems in the country, to date.

To the outside world, the project appeared to be a typical construction project, but to the project team, the project was anything but typical, according to KAI Resident Project Representative Dave Tesson.

KAI Design & Build, partnering as a sub-consultant with global construction management consultant CH2M HILL, served as construction manager on the Metropolitan St. Louis Sewer District's (MSD) $21.2 million Lemay Wastewater Treatment Plant disinfection facility, which included construction of a cutting-edge UV wastewater disinfection system utilizing 3,600 individual UV bulbs and with a treatment capacity of 240 million gallons of effluent per day.

UV irradiation systems disinfect by inactivating pathogenic microorganisms, such as viruses, bacteria and parasites, according to the UV system's manufacturer Ozonia. In the UV-C light spectrum (200-280 nm), the wavelength 254 nm has been proven to be the most efficient wavelength to inactivate micro-organisms by damaging the nucleic acids (DNA and RNA), which disrupts the organisms' ability to replicate. UV has the added advantage that no chemicals are added to the water being treated and no disinfection by-products are formed.

MSD's current boundaries cover 525 square miles and encompass all of St. Louis City and approximately 80 percent of St. Louis County. MSD serves a population of approximately 1.3 million and has over 425,000 single-family residential, multi-family residential and commercial/industrial accounts. MSD currently operates seven wastewater treatment facilities, treating a combined average of 370 million gallons of wastewater per day.

Construction layout and dimensioning of the UV disinfection system's UV channels was a critical component of the project, said Tesson. Requiring approx. 6,500 cubic yards of concrete, an estimated 10,400 wire terminations to connect the UV power and controls, and 560 tons of reinforcement, the system's UV channel widths had to be constructed to an accuracy of +1/2” minus zero inches.

The project also required two, 144” pre-stressed concrete cylinder pipe connections to existing structures carrying the entire plant effluent flow. The existing bulkhead gates in both structures leaked excessively, preventing the removal of the bulkhead pipe caps intended to allow future expansion. The leaks could not be fixed through conventional methods.

"Divers were brought in and were able to seal the leaks from the inside at one of the structures. The other structure required a more extreme approach. Using experience gained from a previous project, the team coordinated an effort to retain wastewater in the collection system and the plant for later treatment. This allowed crews to get inside the structure and work on it dry. Additional wastewater storage was also required to complete modifications of a weir wall within the existing plant piping system," said Tesson.

A final, flow stoppage and storage for the entire plant was required to complete upgrades to the existing incoming plant electrical switch gear. This work required additional coordination with the electric utility to shutdown both utility power feeds to the plant substation.

"The successful completion of this project demonstrates that it is possible for the owner’s project team including the contractor, engineer and construction manager to collectively work together to resolve the many challenges that develop during the construction of a complex project," he said.

Upcoming KAI Water & Waste Water Treatment Projects
KAI has been selected as a sub-consultant to CH2M HILL to provide construction management services on the Missouri River Waste Water Treatment Plant (MRWWTP)-Schedule B project in Omaha, NE. The project, which has been divided into two packages, includes modifications to the MRWWTP to improve water quality, increase plant capacity for future wet weather overflow control, and reduce odors. Upgrades to the existing plant include new chlorination and dechlorination facilities, upgrades to the primary clarifiers, new biological odor controls, an upgrade to the in-plant lift station and new headworks facilities. The construction value of the first package of work is approx. $55 million. The MRWWTP was built in 1964, and at present has an overall average flow capacity of 25 million gallons per day (MGD) and serves approx. 600,000 people. The capacity of the facility will be increased to accommodate a wet weather flow rate of up to 150 MGD.

KAI Texas (an affiliate company) has also been selected to provide third-party construction management services, as a sub-consultant to CH2M HILL, for the Dallas Water Utilities (DWU) ELM Fork, and Bachman Water Treatment Plant projects. Both plants, located in Dallas and Dallas County, Texas are surface water purification/treatment facilities. The two projects are components of a water quality improvement program estimated to have a construction value of $200 million. KAI will support the work of CH2M HILL, which includes inspection of in-progress construction for design compliance, scheduled progress, quality assurance, integrated inspection services with DWU staff, and other related construction management services. DWU has one of the largest water distribution systems in the United States, providing water services to the City of Dallas and 31 surrounding communities. The system serves a population of more than 1.2 million people within the Dallas city limits.