CITY OF LOS ANGELE0- BOARD OF CALIFORNIA DEPARTMENT OF PUBLIC WORKS PUBLIC WORKS

COMMISSIONERS BUREAU OF SANITATION

RITA L. ROBINSON CYNTHIA M. RUIZ DIRECTOR PRESIDENT JOSEPH E. MUNDINE DAVID SICKLER EXECUTIVE OFFICER VICE PRESIDENT ANTONIO R. VILLARAIGOSA VAROUJ S. ABKIAN TRACI J. MINAMIDE PAULA A. DANIELS MAYOR PRESIDENT PRO TEMPORE ENRIQUE C. ZALDIVAR ASSISTANT DIRECTORS

YOLANDA FUENTES 1149 S. BROADWAY, 9'" FLOOR VALERIE LYNNE SHAW LOS ANGELES, CA 90015 TEL: (213) 485-2210 May 8, 2006 FAX: (213) 485-2979

Honorable Jan Perry, Chair Honorable Energy & The Environment Committee Members c/o Frank Martinez, City Clerk Room 395, City Hall

Dear Councilmember Perry:

RE: Odor Control Report related to CF-03-0153-52

The Collection System Settlement Agreement requires the City to submit an annual progress report. The Bureau of Sanitation presented this report to your Committee in February (CF-03-0153-S2) and at that time you expressed concerns over sewer odors and asked for additional information. Enclosed for your Committee's review is a report summarizing Sanitation's efforts over the past several years to reduce sewer odors throughout the City.

If you have any questions or require additional information please contact Adel Hagekhalil of my staff at (323) 342-6225.

Sincerely, ~~ RITA L. ROBINSON, Director Bureau of Sanitation

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AN EQUAL EMPLOYMENT OPPORTUNITY- AFFIRMATIVE ACTION EMPLOYER Recyaab~andmadefromrecyaeciwasla @ BUREAU OF SANITATION ODOR CONTROL PROGRAM

Background All sewers generate a rotten egg-odor caused by , H2S, which is produced by bacteria in the . Significant amounts of H2S gas are produced where sewers bend, change slope, constrict, and pass thru junction and drop structures. This gas can escape from the sewer system through maintenance holes (MHs) and sewer laterals in areas with high sewer gas pressure. The pressure usually increases as the sewer levels rise each day. Large sewers with high flows are particularly susceptible to odor problems caused by the release of H2S gas. Sewer odors are being controlled by limiting the production of this gas and/or preventing it from escaping from the sewer using a combined approach as discussed herein.

Odor Complaint Response and Investigation The Bureau receives sewer odor complaints from various sources including a 24-hour operator-assisted hotline, through the City's website, or the 311 phone number. Field crews investigate and identify the source of the odors and, if sewer related, the crews seal the MH and take other corrective actions when possible. Hotline complaints are followed up within 7 days to inform the complainant of the investigation, corrective actions and to get additional information. Complicated problems are referred to engineers who review the field investigations and sewer design and perform field tests to develop plans to reduce or eliminate the odors. Solutions include moderate repairs, large capital improvement projects, hydraulic relief projects, air treatment facilities, or chemical addition systems.

Routine Sewer Maintenance Obstructions in the sewer slow the sewage flow and cause debris to settle promoting the generation of hydrogen sulfide. Preventative maintenance includes sewer cleaning, root control, inspection/maintenance, and sealing sewer MHs or other access structures to prevent the release of foul odors. An aggressive cleaning program cleans each sewer at least once every five years and more frequently in known "hot spot" areas. Approximately 2800 miles are cleaned annually. Approximately 400 miles of root-infested sewers are treated each year with chemicals to clear roots that contribute to debris settlement.

Trap MHs are used to block sewer gases and are typically located where small sewers connect to larger or interceptor sewers, which tend to have high pressures and high H2S concentrations. New trap MHs have been added to hotspot areas and all trap MHs are now inspected and cleaned on a quarterly basis.

The City has a number of sewer that pass under obstructions such as rivers and large storm drains. These siphons remain full, even with small flows, causing sewage to move very slowly depositing debris that promote H2S generation. To prevent this, siphons are now cleaned quarterly. An air duct called an "air jumper" conveys airflow past a so sewer gasses can travel downstream with the sewage and not buildup pressure as shown below. Our research indicates condensate can fill these jumpers and diminish their effectiveness so they are now inspected on a regular basis to insure they remain clear. Chemical Addition The Bureau started using odor control chemicals in 1997 after extensive analysis was done on complaint history, sewer plans, structures, siphons, and the chemistry of the wastewater. Problem areas were identified and trial applications were conducted to gauge effectiveness and fine-tune the application. Sodium hydroxide is currently applied upstream of the Maze system to control odors in the South LA area. It is added to sewage through MHs upstream of this area one to three times per week, depending on the temperature and time of year, to reduces odors for 3-5 days by elevating the pH of the sewage thereby killing odor-producing bacteria

A second treatment, using magnesium hydroxide, was started in September 2003 and it also raises the pH of sewage to kill bacteria and reduce odors. It is injected continuously at the Union Pacific Pump Plant in Boyle Heights. Another facility for treating the south branch of the Maze sewer system is under design. The following map shows the areas currently receiving chemical treatment in South LA.

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Magnesium hydroxide treatment was recently expanded to treat odors downstream of the Tillman Water Reclamation Plant after a successful pilot indicated it is effective in treating odors in the North Sewer and in the La Coinage San Fernando Relief Sewer. This application has reduced sewer odors around Studio City and Hollywood. Sewer Construction and Repair The Bureau has relieved full running sewers that are experiencing chronic odor problems with new sewers to provide additional capacity and lower sewer gas pressure. The East Central Interceptor Sewer (ECIS) reduced air pressure and odors in the NOS. A similar relief project is being designed to reduce air pressure within the Maze South Branch.

Air Treatment In 2001, extensive monitoring and testing was done to pinpoint the high sewer pressure areas in large sewers located near La Cienaga, Jefferson and Rodeo. Three Air Treatment Facilities (ATFs) were planned and will begin construction to discharge treated sewer gas and relieve the associated sewer gas pressure. Interim carbon scrubbers are being used at these locations until the ATFs are completed. They have been performing satisfactorily although some initial problems occurred on how often the carbon needed to be changed.

Additional ATFs were also planned for four locations on the recently completed ECIS and NElS sewers in anticipation of higher sewer gas pressure. The locations are: 23rd and San Pedro, Mission and Jesse, Humboldt and Ave 20 and Mission and Richmond. Interim scrubbers were installed but subsequent operating experience indicates that not all locations require air treatment and are being re-evaluated. Carbon scrubbers have also been installed at several more locations throughout the City at other odor hotspots. The following is a list of thirteen carbon scrubbers currently being used or planned.

Sewer Odor Control

Location - Current System Type Size Facilities (cfm) Mission & Jesse ECIS Carbon 10,000 23ra & San Pedro ECIS Carbon 10,000 Jefferson & La Cienega ECIS Carbon 10,000 Jefferson & Rodeo NCOS Carbon 10,000 North Outfall Treatment Fac WLAIS Carbon 10,000 MLK & Rodeo Maze Carbon 5,000 Radford & Woodbridge NOS Carbon 5,000 Ballona Pump Plant Marina Carbon 5,000 Genesee & Venice LCSFVRS Carbon 5,000 Humboldt ECIS Carbon 10,000 NORS Portal NORS Carbon 10,000 Richmond ECIS Carbon 10,000 Dakotah Pump Plant BHASS Carbon 3,000

Under Construction System Type Size (cfm)

Sierra Bonita LCSFVRS Carbon 10,000 Monitoring Monitoring stations have been established to identify the cause of sewer odors at known odor hot spots, outfall and interceptor sewers, known pressure zones, areas of turbulence, sharp slope changes in sewer pipes (grade breaks), and sewer pipes with long detention times such as flat sewers. The stations evaluate wastewater chemistry, temperature, H2S concentrations, and air pressure. Monitoring is conducted at least semi-annually at designated points to gage the seasonal variation in odor generation and to monitor the adequacy and effectiveness of any chemical treatment. These results are being used to develop an Odor Master Plan expected to be completed by October 2006.

Conclusion

The Bureau has created an effective odor-control program by employing coordinated measures that address the many causes of sewer odors. The odor complaint hotline allows for a quicker response and resolution of odor complaints. The application of odor control chemicals has reduced hydrogen sulfide concentration in targeted sewers by up to 90%. The use of air scrubbers has reduced sewer pressures and the venting gasses. The construction of relief sewers has reduced the high air pressures occurring in overloaded pipes. The on-going repair of trap MHs and the construction of local sewers have alleviated the movement of odors from large-diameter sewers into neighborhoods, and the maintenance program has decreased the potential for septic conditions. As a result, odor complaints have fallen significantly in the targeted areas. While it is impossible to completely eliminate sewer odors, the Bureau has and will continue to mitigate odors through monitoring, complaint response, and effective implementation of odor control technologies.

One major element of this program, the ATF element is currently under review and the Bureau will report its finding on this element within the next couple of months.