13 - Lift Station Odor Control Plan Costa Mesa Sanitary District
…an Independent Special District
Protecting our community’s health and the environment by providing solid waste and sewer collection services.
www.cmsdca.gov
Memorandum
To: Board of Directors
From: Scott Carroll, General Manager
Date: October 24, 2013
Subject: Lift Station Odor Control Plan
Summary
The Board directed staff to develop an odor control plan for lift stations noting areas with
historical odor complaints and a list of projects to mitigate the odors. The Board also
requested an impact summary on how downspouts can effectively reduce odors in wet
wells.
Staff Recommendation
That the Board of Directors receive and file the report.
Analysis
Background
Hydrogen Sulfide (H 2 S) gas is typically formed in sewer lift stations that have a flat grade
or do not have the flow-through velocities to prevent the stagnation of fluid and allow
septic conditions to occur. Septic conditions occur when bacteria use all of the available
oxygen while decomposing organic matter in wastewater for energy. Sewer with low
velocities encourages the growth of anaerobic bacteria in a slime layer coating the sewer.
These bacteria reduce sulfur compounds such as sulfate (SO4), thereby producing
sulfides (SO2). Under anaerobic (septic) wastewater conditions, sulfides cannot be
oxidized. Therefore, they combine with hydrogen to produce hydrogen sulfide gas,
creating the “rotten egg” odor associated with wastewater in lift stations.
ITEM NO. 13
Board of Directors
October 24 , 2013
Page 2 of 4
Odor Complaints
In 2013, the District received six documented odor complaints related to sewer system;
however, after further investi gations staff determined that the odor was originating from
Orange County Sanitation District facilities. Below are more details regarding the odor
complaints.
1. In January 2013, staff received a complaint about possible odors occurring on I405
southbound freeway between Harbor Blvd and Fairview Avenue. Staff determined
that the closest sewer system to this location is the OCSD Red Hill Gisler
Interceptor and therefore cont acted OCSD staff to suggest investigating the sewer
line.
2. In June 2013, staff received a complaint about odors coming from the District’s
California Lift Station. After receiving the complaint staff placed an odor logger
inside California’s wet well where the results were below CMSD’s standards , which
is below 1.0 ppm (parts per million). Staff believes the odor was coming from
OCSD’s treatment plant and therefore contacted OCSD’s Control Center.
3. In July 2013, staff received two odor complaints for the in tersection of Baker and
Red Hill. Staff checked the CMSD manholes and the OCSD force main manhole
and determined that the odor is coming from OCSD’s force main. Staff notified
OCSD staff to suggest they clean this manhole.
4. In September 2013, staff receiv ed notification from South Coast Plaza management
that the lift station was emitting strong odors. Staff immediately washed down the
wet well to help control the odors. Odors typically occur at this pumping station
when the upstream restaurants have a bus y weekend and then wash the H2S
laden wastewater into the District’s station.
5. In October 2013 staff received an odor complaint from a resident who lives on Iowa
Street. Staff investigated CMSD’s Iowa Lift Station and did not detect any odors.
Staff believes the odor was coming from OCSD’s large nearby trunk sewers or
treatment pla nt .
Historically, CMSD would receive odor complaints about the Elden and South Coast Plaza
Lift Stations, but in 2013 staff has not received any complaints because of the corrective
measures CMSD recently took to reduce H2S levels by installing down spout s. Down
spouts allow the incoming wastewater to enter the wet well below the current water level,
thereby reducing the turbulence and the off -gassing of hydrogen sulfide. This reduces
both odor and the formation of a corrosive atmosphere. As a result of i nstalling
downspouts H2S levels have decreased from 211 ppm to 35 ppm at Elden Lift Station and
from 141 ppm to 9 ppm at South Coast Plaza Lift Station. The South Coast Plaza Lift
Statin is averaging 1 ppm. Staff plans on installing a secondary downspou t at the Elden
Lift Station to reduce the ppm levels to less than 10 ppm. In addition, staff has been
successfully working with South Coast Plaza management to work with restaurants
Board of Directors
October 24 , 2013
Page 3 of 4
owners/managers on applying chemicals in their grease interceptors to help mitigate H2S
levels.
Odor Control Plan
The following is CMSD’s plan to minimize, reduce and/or eliminate H2S from lift stations.
Wet wells are cleaned annually and washed down when necessary . Also, the Flygt
pumps allow the water level to be pumped down by an operator to almost to the
bottom of the well (“snored”) causing mixing of the remaining water and anything
remaining. This prevents grit and solids from accumulating at the bottom of the wet
well.
Odor b locks (deodorizers) are placed inside wet wells.
If lift station s are continually experiencing high levels of H2S (averaging higher than
1.0 ppm per day ) then staff will condu ct a cost analysis to install down spout s
versus applying chemicals in the wet we ll or using other methods such as air
scrubber systems, wet well aeration, etc .
Strategic Plan Element & Goal
This item complies wit h objective and strategy of Strategic Element 1 .0., Sewer
Infrastructure , which states:
“Objective: To collect and transport wastewater to meet the needs of existing and future
customers.
Strategy: We will do this by the careful management of the collection infrastructure using
prudent planning and maintenance, with financial strategies to maintain suffic ient capacity
and respond to changing regulatory demands .”
Legal Review
Not applicable
Environmental Review
The installation of an odor control system is categorically exempt under the California
Environmental Quality Act (CEQA) (Public Resources Code Section 21000 et. seq.) under
Section 15301 as a “Class 1” “minor alteration of existing public or private structures”, as
further described in Section (b) as “Existing facilities of both investor and publicly -owned
utilities used to provide …. sewerage …”
Financial Review
T he cost to install down spouts in lift stations can range from $7,000 -$12,000 depending
on station’s capacity. This would be a onetime cost compared to applying chemicals in
wet wells that will be an on -going annual expense that can be as high as $20,000 a year.
Board of Directors
October 24 , 2013
Page 4 of 4
Public Notice Process
Copies of this report are on file and will be included with the entire agenda packet for the
October 24 , 2013 Bo ard of Directors regular meeting at District headquarters and on
District’s website.
Alternative Actions
1. Direct staff to report back with more information