Pretreatment Program Phase II

West Mifflin Sanitary Sewer Municipal Authority's pretreatment program was introduced in the early winter of 2000. The program, which regulates the discharge of Fats, Oils, and Grease into the West Mifflin Sanitary Sewer Municipal Authority treatment plants by food handling establishments, has become a pilot program for many surrounding communities to follow. With the guidance of Compliance Consulting, Inc. and their consultant, Pat Tripodi, West Mifflin Sanitary Sewer Municipal Authority pretreatment program is 99% complete, bringing food handling establishments into compliance. The requirements, or limits allowed, are not to exceed 200 parts per million of Fats Oils or Grease discharged into the collection systems of West Mifflin Sanitary Sewer Municipal Authority. The respective establishments are required to have a passive out door grease interceptor, or have an automatic or semi-automatic grease recovery system properly sized and placed inside their food preparation areas. The cooperation, of the establishments affected by our program, has been remarkable and it shows that most of our residents and businesses are interested in preserving the environment.

We, as regulators of this program, are very appreciative of this cooperation.

The Pretreatment program will continue to be an ongoing regulatory agency and will be expanded to include automobile dealerships, repair garages, car washes and photo processing areas.

Dye Testing

Under the Consent order, we were mandated to dye test all homes inĀ  West Mifflin Borough to determine which homes were using down spouts, garage drains and storm drains to disposes of storm water into the sanitary sewer system.West Mifflin must stop using the sanitary sewer system for storm water run-off.

The Sewage Treatment Plants are overburdened with the influx of storm water run-off when added to its normal volume. The influx causes the plants to overflow into streams. Treating the additional water plus the daily sewage increases expenses. The dye testing of all West Mifflin homes is complete. This program has eliminated approximately 95% of the storm water that was coming into the Sewage Treatment Plants.

WMSSMA is continuing to monitor the situation by requiring a dye test of homes to be sold before the sale is completed. To better serve our customers the Authority can conduct the dye test and release the paper work ($95), or the customer may have a private plumber dye test the home($ cost homeowner), send the results in, and the paper work is then processed ($25). Anyone requiring more information can contact our offices at (412) 466-6070, Monday thru Friday 7 AM to 3 PM.

Original consent order with boro of West Mifflin

Thompson Run Sewage Treatment Plant:

The Thompson Run Sewage Treatment Plant improvements project involved the construction of a new Sequencing Batch Reactor (SBR) treatment system being incorporated into the existing conventional activated sludge process. The new SBR has a peak capacity of 5 million gallons per day (mgd) with an average dry weather design flow of 1.5 mgd. The two systems together can handle a peak flow of 9 mgd. Each system is continuously fed through either the influent pumps or by gravity. Splitting the flows between the conventional process and the new SBR is controlled by a PLC system that can easily be programmed to accommodate operational changes. At this time, the PLC is programmed such that the Homeville/Kenmore watersheds are discharging into the SBR and the remaining watershed flows are pumped to the existing plant.

The SBR system includes a headworks system that includes a self-cleaning fine screen followed by a grit removal changer. Pretreated sewage will flow continuously from the headworks into the two SBR aeration tanks that are operated in parallel for BOD and ammonia nitrogen removal. Treated effluent is discharged into an ultraviolet disinfection system prior to combining with the existing STP effluent and discharging to Thompson Run through a new 36 inch outfall pipe.

The SBR system utilized at the Thompson Run STP is an Intermittent Cycle Extended Aeration System (ICEAS). The ICEAS system incorporates continuous activated sludge technology with intermittent systems operation. The system uses a single vessel in which the activated sludge is alternately aerated and mixed over a number of pre-determined cycles. Solids liquid separation occurs during the settling phase of the cycle. After the settling phase, treated effluent is decanted or withdrawn from the liquid surface. Flow to the vessel is not interrupted at any time. The functions of flow equalization, biological oxidation, nitrification, denitrification, sedimentation and aerobic sludge stabilization are carried out in a single basin. The ICEAS system has both a normal cycle and a storm cycle. During the normal operations, aeration occurs for 120 minutes, settling occurs for 60 minutes and decant occurs for 60 minutes for a total cycle time of 4 hours. During the storm cycle, the aeration time is decreased to 90 minutes, settling occurs for only 45 minutes and decant occurs for 45 minutes for a total cycle time of 3 hours. This storm cycle allows the peak flow rate of 5 mgd. to be treated.

New England Plant:

Construction began in 1999 on the new Digester at the New England Sewage Treatment Plant. This plant had one existing digester and after construction their will be two working digesters. A Digester is a large above the ground tank that looks somewhat like a silo, and this tank is used for micro-organisms to decompose the sludge. More simply a digester acts like a human's stomach digesting food. The digester is heated to keep the micro-organisms warm and happy so they can do their best work.

New England Sewage Treatment Plant will also have a new 550,000 gallon capacity Equalization Tank. This tank holds the overflows going into the plant and releases them slowly to be processed.

Pump Stations:
The following is a list of the West Mifflin Sanitary Sewer Municipal Authority's Pumping Stations. The purpose of a pumping station is to receive the sewage from local areas and pump it onward toward the plant that will process this sewage:

  • Airport
  • Belmont
  • Brieck Hollow
  • Carolina
  • Curry Hollow
  • Homeville
  • Kenmore
  • Maryland
  • Mid City
  • New England
  • Regis
  • Route 51
  • Saniel McGowan
  • Route 885