Wastewater Treatment Plant Upgrades

Borough of Orwigsburg Orwigsburg, PA



The Borough of Orwigsburg Wastewater Treatment Plant (WWTP) provides wastewater treatment for approximately 1,500 customers in and around Orwigsburg. The WWTP is rated for 0.9 million gallons per day (mgd) and an influent organic load of 1,501 pounds per day (ppd) as measured as biochemical oxygen demand (BOD). The site has two buildings, a Control Building and Blower/Generator Building. The solids handling process includes three aerobic digesters each with a capacity of approximately 133,000 gallons, and six reed beds with a total area of 10,400 square fee

After being in operation for nearly 20 years, it was time to upgrade various treatment plant equipment for improved capability and efficiency, as well as better meet demand during wet weather and anticipate future regulatory requirements. Entech provided design, permitting, bidding and services during construction for the two phases of upgrades.

Solution Details

The WWTP Improvements project was implemented in two phases.

Phase 1

Phase 1 included new samplers, influent flow metering equipment, and influent pumps. Equipment in the existing clarifiers was warped and leaking. They were retrofitted with new launders, baffles and weirs. Launder covers were added to prevent sun damage and algae growth, providing longer life for the equipment and greatly reducing maintenance time for staff. A return activated sludge (RAS) pump was replaced with one the Borough already had on hand. VLR drives and bearings were replaced, with water quality instrumentation (to test for DO, pH, and TSS) added to allow for aeration adjustments and continuous water testing. More efficient and effective site lighting was also added to the treatment plant and grounds.

Phase 2

In Phase 2, surface aerators in the digesters were replaced with coarse bubble diffusers & blowers, providing more efficient aeration and mixing in the tanks. The UV system, having reached the end of its useful life, was replaced in-kind with new equipment. In addition, the effluent weir was raised. The previous position of the weir was causing erroneous high-level readings. By raising the weir, readings are more accurate during storm conditions. The upgrade also included a new SCADA system.

Once completed, the improvements also achieved Class B sludge digestion to allow the dewatered cake to be landfilled or potentially land applied. All improvements were completed within the existing footprint of the treatment plant without interruption of services. The Borough has a more effective and efficient plant, requiring less maintenance, with systems that can adapt to changing conditions and regulatory requirements.

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