Administrative Brief
COMMISSION INFORMATION MEMORANDUM
VOL. 26, NO. 16 May 21,
2004
ADMINISTRATIVE BRIEF FROM MARTHA TASKER:
Public Works/Wastewater Division
The City of Salina Wastewater Division experienced significant amounts of grease sinking in the
process tanks and stoppages in the piping at the Wastewater Treatment Plant (WWTP) in 2000 and
2001. In 2001 piping was disassembled and it was discovered the piping was nearly plugged with
grease on the average a 2 inch or less opening was found in the 6” piping.
City staff has installed twenty-four piping clean-outs to remove the grease build-up. The materials
cost $13,000 and required approximately 1500 man-hours to install. The lines are cleaned twice
per year which takes approximately 100 man-hours per year. Wastewater staff has identified areas
where the sewer collection system requires cleaning more frequently due to grease build up and
FOG (fats, oils and grease). In September 2002, the City contracted with Camp Dresser & McKee
Inc. (CDM) to conduct an investigation into the grease problems experienced at the WWTP.
Continental Analytical Services analyzed the grease accumulations in the piping and the results
indicated that the grease accumulation was animal and vegetable in nature and not petroleum
based. Fats, oils and grease of the animal and vegetable nature are found in waste streams from
industrial/institutional food process facilities, restaurants and residential homes.
The City’s Industrial Pretreatment Program regulates/permits fifteen industries and of the fifteen,
two are permitted for oil and grease. These two industries are food process facilities (Ramaco Inc.
and Schwan Sales Enterprises) which are permitted yearly and monitored on a regular basis.
Ramaco Inc. pretreatment waste flow is a batch removal process and waste FOG is removed for
resale. The City has not experienced problems from this industry. Schwan Sales Enterprises and
City staff have met and City and CDM staff visited the pretreatment facility to determine the
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effectiveness of the pretreatment process to remove FOG. Data indicated that high FOG levels
occurred during night shift clean-up periods. Significant improvements were made by Schwan Sales
Enterprises to meet Pretreatment Permit requirements. Additional sampling has been completed
and the pretreatment process is working efficiently and meeting Pretreatment Permit requirements.
CDM’s Grease Investigation recommended that the City remain diligent in grease trap and
interceptor inspections and maintain a strong stance on installation of grease traps and interceptors
at existing and new food service facilities.
Current City Ordinances and the Plumbing Code require food service facilities to install grease traps
or interceptors. In 2003, City staff conducted inspections of lo cal restaurants and institutional
facilities and the inspections revealed a general lack of maintenance of grease traps and
interceptors. A total of 178 full service restaurants, 14 full service schools and 46 food services
inside retail businesses were inspected. Thirty of these facilities did not have grease traps and
interceptors and the majority of the other fac ilities did not maintain accurate records of
maintenance/pumping of the grease traps and interceptors.
During 2003/2004 City staff has inspected the grease traps and interceptors on approximately three-
month intervals and have found that these facilities have improved their grease trap and interceptor
maintenance and record keeping. City staff has worked with these facilit ies to promote Best
Management Practices in an effort to reduce the amount of FOG being discharged into the public
sewer system by food service and preparation facilities.
Residential customers also cont ribute to the total volume of FOG load at the WWTP. While
ordinarily these concentrations may not be significant by themselves, combined with other sources
the volume can be significant. Public education on FOG reduction methods is an important factor
in reducing FOG loads at the WWTF. Many cities have adopted programs to educate the public on
this issue, such as Wichita, Kansas and Little Rock, Arkansas.
CDM’s Grease Investigation noted that chemically altered sol uble oils and greases that are
converted to soaps and precipitate at the WWTP are most likely coming from facilities performing
cleanup activities. Due to the volume and the water hardness in the sanitary sewer flow, reversing
this reaction once the discharge enters the sanitary sewer is not deemed economically feasible. The
best method to reduce oils and grease and its associated problems is to control the quality and
quantity of discharge at the source. City staff continues to identify and evaluate sources of FOG
loading to the WWTP.
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Based upon an average flow to the WWTP of 5 MGD and a influent FOG concentration of 35 mg/
for domestic sewage a reasonable goal for FOG load to the WWTP should be less than 1,450
pounds per day. In 2004 the FOG load averaged 2,400 pounds per day or additional 175 tons of
FOG per year, which is equal to approximately 460 trash carts full of grease.
CDM’s Grease Investigation recommended the City continue efforts to identify sources of FOG
loading. Reducing the FOG volume will minimize the chances for sanitary sewer overflows in the
collection system, and decrease operational and maintenance costs at the WWTP.
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City staff continues to conduct inspections of local restaurants and institutional facilities at
approximately three-month intervals and providing assistance and guidance in the proper installation
and maintenance of grease traps and interceptors. Our goal is to work together with the food
industry to find ways to reduce/eliminate F OG quantities. This will reduce operating and
maintenance costs of the wastew ater system which in turn will reduce costs to City of Salina
customers.
MONDAY'S MEETING:
1. Enclosed are other items on the agenda. If any Commissioner has any questions or
cannot attend the meeting, please contact me.
2. Let’s begin the study session at 2:30 p.m. An agenda is attached.
Dennis M. Kissinger
City Manager