Sharon Wastewater Treatment Plant

The City of Sharon (PA) Sanitary Authority’s Water Pollution Control Facility (WPCF) was expanded and improved to enable the Authority to meet more stringent National Pollution Discharge Elimination System (NPDES) effluent limitation requirements.

The facility offers operating staff the flexibility to handle fluctuating organic loads as well as high hydraulic excursions during extraordinary weather events.

The WPCF serves the residents of the City of Sharon and the Upper Shenango Valley Water Pollution Control Authority (USVWPCA) in Pennsylvania, and a small portion of Brookfield Township, in Trumbull County, Ohio. The USVWPCA consists of the Borough of Sharpsville, the City of Hermitage, and the west side of South Pymatuning Township. The WPCF is located on a triangular shaped 7.5-acre tract of land that is bounded by US Route 62 on the north, Norfolk Southern Railroad on the west, and the Shenango River on the southeast.

Improvements to the WPCF resulted from a Consent Order and Agreement (COA) entered in November 2002 by and between the PADEP, the City of Sharon, and the USVWPCA. The project eliminated hydraulic overloads in the collection system (Connelly Boulevard siphon) and hydraulic and organic overloads of the treatment facility that caused violations of the NPDES permit.

Construction of the facilities began in October 2007 and continued through early 2010.

How does the plant work?
Flow from the City of Sharon collection system enters an influent pump station that discharges to the influent building where the flow combines with the flow from the USVWPCA Orangeville Pump Station. Screening and grit removal is provided in the influent building as well as flow monitoring for compliance and billing purposes.

Flows are channeled through the division well into the primary clarifiers. During high flow events the flow is diverted to the equalization (EQ) basin that functions as a primary clarifier/EQ basin. Primary clarifier effluent is discharged to a primary effluent pump station for conveyance to two trickling filters. The primary effluent pump station also houses primary sludge pumps that discharge to four aerated sludge storage tanks.

Discharge from the trickling filters is channeled through two aeration/solids contact tanks. These tanks allow for:

1. Recirculation back to the trickling filters through the primary effluent pump station during low flow periods; and
2. Introduction of return activated sludge from the secondary clarifiers.

Effluent from the aeration/solids contact tanks is channeled to three secondary clarifiers. Secondary sludge removal is handled by a secondary sludge pump station capable of pumping return activated sludge to the aeration/ solids contact tanks and waste activated sludge to the aerated sludge holding tanks. Effluent from the secondary clarifiers enters an ultraviolet (UV) disinfection basin where non-potable water is also withdrawn for plant operations.

Effluent from the UV basin enters a Parshall flume for flow metering prior to cascade aeration and final discharge into the Shenango River.

A thickening centrifuge and a dewatering centrifuge perform solids handling duties. The thickening centrifuge is fed from the four aerated sludge storage tanks and stored in two aerated sludge storage tanks prior to dewatering for eventual disposal.

Innovative use of alternative technology
The trickling filter/solids contact process was chosen to meet anticipated future permit limits and provide for flexible operation at lower capital and operating costs. In addition, the trickling filter process permits the facility to adequately address higher organic loading excursions emanating from an industrial source while consistently meeting effluent limits and minimizing upsets to plant processes.

Dual use of the EQ basin as a primary clarifier/EQ basin allowed for the treatment facility to meet its requirements for average daily and peak hourly flows, without incurring additional costs to expand primary clarification on a limited site footprint.

Additional improvements to the plant also include administrative offices, laboratory facilities and a garage/maintenance facility.

Three generators provide standby emergency power throughout the treatment facility. Based on full load operations, emergency power can be provided for a minimum of 16 hours prior to refueling the diesel-fired engines.

By using existing plant infrastructure as part of the upgraded design, approximately $2.5 million was saved in project costs.

Effective in January 2009, the City of Sharon Sanitary Authority assumed all assets and operational control of the wastewater system from the City of Sharon. The Authority continues to enhance the operations to ensure the long-term viability and cost effectiveness of its system.

Please contact John Pierko, P.E. at 330.744.5321 for more information about this and other environmental projects.