The sanitary sewer system of Conewago Industrial Park Water and Sewer Company consists of 6", 8" and 12" mains and a wastewater treatment plant (WWTP). The WWTP has the capacity to process an annual average daily flow of 50,000 gpd, a peak month flow of 95,000 gpd, and a peak day flow of 150,000 gpd. The current NPDES permit issued by the Pennsylvania Department of Environmental Resources allows a discharge of 150,000 gpd.
The WWTP consists of a 150,000 gpd Sequencing Batch Reactor (SBR) activated sludge plant. The WWTP utilizes SBR equipment and components fabricated by Aqua-Aerobics Systems, Inc., installed inside of precast concrete process tanks fabricated by Dutchland Inc.
The WWTP includes a comminutor (with bar screen bypass), a pre-equalization tank, an SBR tank, a post-equalization tank, five blowers (to introduce air into the process tanks), a sludge digester tank, two sludge holding tanks, and disinfection facilities followed by stream discharge. The pre-equalization tank is sized to handle diurnal peak flows while the SBR is in reaction, settling, and discharge modes. The duration of the treatment cycles can also be shortened to handle flows during extreme wet weather conditions. Sludge wasted from the SBR process is directed to the sludge digester and is aerated by blowers. Sludge is removed as needed by the operator. When sludge is removed, the aeration is shut off and the sludge settles. The supernatant is pumped to the pre-equalization tank.
The waste sludge is hauled off-site to an approved facility.
Four chemicals are presently added for optimum treatment efficiency and solids settling. Hydrated lime and alum are added manually to the pre-equalization or SBR tanks as needed. Deltafloc and Superfloc are automatically added to the SBR tank using chemical feed pumps controlled by a timer integrated with the SBR cycles.
There are no pumping or lift stations. There are no pressurized mains.
The electrical service to the plant is 480 volt, 3 phase, 4 wire, 600 amps. There is a 400 kw diesel-powered emergency generator to provide a second source of electricity for the pumps and blowers.