Wastewater Treatment Plant

Wastewater Treatment Plant


1930’S – Original plant construction. Plant provided primary treatment with Imhoff Tank.

1956 – Plant expanded to one (1) MGD and upgraded to include secondary treatment. Expansion included the following:

1. two (2) primary clarifiers

2. one (1) decant tank

3. one (1) final clarifier

4. one (1) set of step aerators -Imhoff tank converted to sludge digester

  • Sludge drying beds upgraded 1966
  • Plant became hydraulically and organically overloaded.

1986 – Plant expanded to present status of two (2) MGD tertiary treatment.

The Somerset Borough Wastewater Treatment Plant is a 2.0 million gallon per day advanced wastewater treatment plant. The wastewater is brought to the treatment facility through over twenty-eight miles of underground sewer lines and five (5) pumping stations. As the raw wastewater enters the facility, it first passes through the preliminary treatment process where rags, grit, and other debris are removed or shredded for further treatment. The wastewater now flows into the main wetwell where it is then pumped up to the beginning of the primary treatment stage. In primary treatment, the wastewater flows are measured and split up into four (4) rectangular twelve (12) feet deep primary clarifiers where the velocity of the wastewater is slowed to allow the settleable matter to precipitate to the bottom of the clarifiers. This settled matter (sludge) is removed from the clarifiers and placed in a separate treatment process. Greases and other floating debris are also removed in the primary clarifiers.

After the wastewater passes through the primary clarifiers it is ready to go on to secondary treatment. This stage is a biological form of treatment and is the heart of the treatment process that is split into two (2) steps. In the first step, the wastewater splits and flows into two (2) roughing trickling filters that are seventy-five (75) feet in diameter and four (4) feet deep. These filters are filled with a synthetic honeycombed media. The media provides an area for bacteria to grow. These bacteria feed on the organic matter in the wastewater, thus eating the pollutants out of the wastewater. The wastewater flow is distributed over the media through rotary distributor arms. Some of the flow that passes through these filters is recycled for a better degree of treatment.

Sewer PlantThe remainder of the flow goes on to the second step in the secondary treatment process. In the second step of this process the wastewater is pumped up to the bio-towers. These bio-towers are similar to the roughing trickling filters in that they also are packed with a synthetic media that the wastewater flows through. The differences between the bio-towers and the roughing filters is that the bio-towers are thirty (30) feet tall and forty-five (45) feet in diameter and the bacteria growing in the bio-towers is different from those in the roughing trickling filters to remove a different type of pollutant and the synthetic media is slightly different also. A portion of the flow off of the bio-towers is recycled for a greater degree of treatment.

After the flow passes through the two (2) steps of biological treatment, it splits up into three final clarifiers where the velocity of the wastewater is again slowed to allow the remaining solid matter in the wastewater to settle out. After the flow passes through the final clarifiers it is ready to go on to the final stage of treatment known as disinfection. The flow now splits up into two (2) contact chambers where chlorine is added to kill off the harmful bacteria that may be present in the wastewater. After the wastewater goes through this stage of treatment, it is discharged into the east branch of Coxes Creek. The wastewater discharged must meet strict federal and state guidelines. This is achieved only through carefully monitoring the various treatment processes and making process control changes accordingly. At present, the treatment plant treats about 1.5 million gallons of wastewater per day. During periods of heavy flows, the treatment plant can handle up to 5.0 million gallons per day and divert another 2.2 million gallons into the storm overflow lagoon, making the total peak capacity for a twenty-four (24) hour period about 7.2 million gallons. Any wastewater that is diverted into the lagoon is pumped back to the head of the treatment process for complete treatment when the heavy flows subside.

As for the solids (sludge) that are removed from the clarifiers in the various stages of treatment, they are placed in their own specialized biological treatment process knows as two (2) stage anaerobic digestion. This process takes upwards of twenty-eight (28) days to complete. In this process, the sludges are broken down and stabilized. A by-product of this treatment process is methane gas that is captured and used for heating the sludges and buildings. After the sludge passes through the anaerobic digestion process it is run through a device called a belt filter press. The belt press removes the water from the sludge and the dewatered sludge is then placed in a dumpster. The dumpster once filled, is hauled to a specially permitted landfill where the sludges are disposed of. At present, Somerset Borough hauls about fourteen (14) tons of sludge per week to the landfill.

The Somerset Borough wastewater treatment plant is staffed seven days a week by state licensed operators who are responsible for all aspects of operation and maintenance of the complex wastewater treatment facility. We hope these few brief paragraphs have been informative to you. Should you be interested in a group tour of our treatment facility, please contact the Water and Sewer Department at 814-443-2661. We appreciate your time in looking over the materials we have provided to you. It is imperative that we protect our environment from pollution as water is certainly a vital component in the future of mankind. Again, thank you for your time and interest.

Sewer Plant