Civil Engineering Reference
In-Depth Information
Project:
City of Wichita Ozone Facility for Taste-and-Odor Improvements
Owner:
City of Wichita, Kansas
Design-Build (DB) Entity:
Utility Contractors Inc. (contractor); EarthTech
(engineer)
Completion Date:
June 2004
Description of Project
In February 2004, the City of Wichita procured a design-builder to design and con-
struct an ozonation facility for taste-and-odor improvements. The taste-and-odor
problems in the Wichita water were caused by the presence of seasonal algae blooms
in the water at Cheney Reservoir. Wichita needed a solution to quickly address the
situation and ease public concerns.
A building was designed to house an ozone generation system using a pro-
cess that was designed to meet the hydraulic capacity and ozone dose at specified
conditions:
Parameter
Minimum
Average
Maximum
Hydraulic Capacity (mgd)
20 (76 ML/d)
50 (190 ML/d)
80 (303 ML/d)
Ozone Dosage Rate (mg/L)
1
3.5
5.0
Water Temperature (ºF)
33 (0.6 ºC)
59 (15 ºC)
83 (28 ºC)
The process uses liquid oxygen from storage tanks to create ozone, which is
then mixed with the main water flow in an ozone contactor. To remove the taste and
odor sufficiently, the ozone contactor was designed for a 5-min retention time at 80
mgd (303 ML/d).
Normally, a concrete tank is constructed to be used as the ozone contactor.
Ozone's highly corrosive characteristics make concrete with sufficient cover over
steel reinforcement the preferred material. The high internal pressures of this sys-
tem, however, would not allow a traditional concrete tank to be used. The design-
builder developed a unique solution for the ozone contactor and mixing facility.
Two parallel 750-ft (229-m) lines of 72-in. (1.8-m) diameter custom-manufactured
concrete pressure pipe were designed and installed as the ozone contactor. Due to
ozone's corrosive nature, each of the 70 pipe pieces was made with stainless-steel
joint rings instead of traditional carbon steel.
The design-builder's selection of prestressed concrete cylinder pipe with the
stainless-steel joint rings met the project requirements for ozone corrosion resistance,
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