Title

Safe Disinfection of Potable Water: Design of the North Stockton Pipeline Sodium Hypochlorite Facility

Lead Author Major

Civil Engineering

Lead Author Status

Senior

Second Author Major

Civil Engineering

Second Author Status

5th year Senior

Third Author Major

Civil Engineering

Third Author Status

Senior

Fourth Author Major

Civil Engineering

Fourth Author Status

5th year Senior

Format

SOECS Senior Project Demonstration

Faculty Mentor Name

Mary Kay Camarillo

Faculty Mentor Email

mcamarillo@pacific.edu

Faculty Mentor Department

Civil Engineering

Additional Faculty Mentor Name

Luke Lee

Additional Faculty Mentor Email

llee4@pacific.edu

Additional Faculty Mentor Department

Civil Engineering

Additional Faculty Mentor Name

Hector Estrada

Additional Faculty Mentor Email

hestrada@pacific.edu

Additional Faculty Mentor Department

Civil Engineering

Additional Mentors

Dr. Camilla Saviz / csaviz@pacific.edu / SOECS - Civil Engineering

Abstract/Artist Statement

Formation of disinfection by-products (DBPs) and trihalomethanes (THMs) in potable drinking water have become of increasing concern to the public in recent years. To mitigate this issue, the City of Stockton (City) converted their existing chlorine disinfection system to a safer method of disinfection, chloramination. Chloramination is the practice combining free chlorine with ammonia to form a weaker, but more stable disinfectant that does not interact with organic matter to form DBPs and THMs. However, events of DBP and THM formation have arisen because of the disinfection practices of Stockton East Water District (SEWD). SEWD currently disinfects their filtered effluent with 3 to 4 mg/L of chlorine gas, which is then conveyed through a 5-mile pipeline. During transportation of the disinfected water to the City’s customer connections, the high concentration of chlorine reacts with organic matter to form DBPs and carcinogenic THMs. The City has proposed to add sodium hypochlorite (hypochlorite) at the existing North Stockton Pipeline Ammonia Facility (NSPAF) site, located a few thousand feet upstream to the first customer connection. The North Stockton Hypochlorite Facility (NSPHF) was designed with two 7,000 gallons tanks to inject free chlorine concentrations ranging from 1.75 to 2.75 mg/L. The injected hypochlorite will be initially blended by two pumped-jet mixing nozzles to provide a mixing gradient of 800 to 1,000 s-1. Supplemental mixing will be provided downstream by one of three static mixers. A high-degree of blending must be achieved to ensure adequate blending across the pipeline cross-section before mixing with the injected aqueous ammonia to form mono-chloramines. The oral presentation on this design will cover the specifics of chloramination, the design of the NSPHF, and the impact of the facility’s operations on the City’s potable water supply.

Location

School of Engineering & Computer Science

Start Date

5-5-2018 3:30 PM

End Date

5-5-2018 4:30 PM

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May 5th, 3:30 PM May 5th, 4:30 PM

Safe Disinfection of Potable Water: Design of the North Stockton Pipeline Sodium Hypochlorite Facility

School of Engineering & Computer Science

Formation of disinfection by-products (DBPs) and trihalomethanes (THMs) in potable drinking water have become of increasing concern to the public in recent years. To mitigate this issue, the City of Stockton (City) converted their existing chlorine disinfection system to a safer method of disinfection, chloramination. Chloramination is the practice combining free chlorine with ammonia to form a weaker, but more stable disinfectant that does not interact with organic matter to form DBPs and THMs. However, events of DBP and THM formation have arisen because of the disinfection practices of Stockton East Water District (SEWD). SEWD currently disinfects their filtered effluent with 3 to 4 mg/L of chlorine gas, which is then conveyed through a 5-mile pipeline. During transportation of the disinfected water to the City’s customer connections, the high concentration of chlorine reacts with organic matter to form DBPs and carcinogenic THMs. The City has proposed to add sodium hypochlorite (hypochlorite) at the existing North Stockton Pipeline Ammonia Facility (NSPAF) site, located a few thousand feet upstream to the first customer connection. The North Stockton Hypochlorite Facility (NSPHF) was designed with two 7,000 gallons tanks to inject free chlorine concentrations ranging from 1.75 to 2.75 mg/L. The injected hypochlorite will be initially blended by two pumped-jet mixing nozzles to provide a mixing gradient of 800 to 1,000 s-1. Supplemental mixing will be provided downstream by one of three static mixers. A high-degree of blending must be achieved to ensure adequate blending across the pipeline cross-section before mixing with the injected aqueous ammonia to form mono-chloramines. The oral presentation on this design will cover the specifics of chloramination, the design of the NSPHF, and the impact of the facility’s operations on the City’s potable water supply.