Treatment Plant History

The existing Piqua Wastewater Treatment Plant was originally constructed in 1957-1958. It had a nominal design capacity of 4.0 mgd and a peak-pumping rate of 7.0 mgd. The original plant consisted of barminutors, raw sewage pumps, raw sewage metering, chemical mix basin for feeding lime and ferric chloride, pre-aeration basin equipped with grit collector equipment, two (2) primary settling tanks, four (4) aeration basins, two (2) secondary settling tanks, one (1) plant effluent pump, two (2) anaerobic digesters with floating covers, and a sludge dewatering vacuum filter. 

In 1969, additional treatment units were added in order to upgrade the performance of the plant. The additional units included one (1) secondary settling tank, chlorination building with a chlorine contact tank, and an aerobic digester process.  

In 1984, modifications were made to the existing anaerobic digestion system, gas handling, and flow monitoring systems. This was needed to meet the increasing and more stringent discharge regulations. The modifications included replacement of an existing anaerobic digester cover to a fixed lid configuration. The gas mixing handling system was modified to include three (3) gas bubble-mixing guns. Flow metering equipment and modifications were added to existing primary and secondary settling tanks.  

The 1988-1989 Plant Expansion added many new tanks and equipment to help meet the Clean Water Act Regulations of 1972. The Methane Gas created in digestion of sludge is used to burn in the sludge heat exchanger for the pathogen treatment of biosolids. During this time period a new "Caterpillar" methane-burning engine with blower was added, for the plant’s aeration purposes and to save on electrical energy costs. Three (3) new screw-type raw sewage pumps were added along with a new wet well area. A new grit and grease process removal system with new flow channels and equipment was also added. A new primary settling tank, two (2) new aeration basins (2 passes per basin) with all the aeration receiving four (4) new internal recycling pumps to aid in the ammonia removal, and two (2) final settling clarifiers (with piping and electrical for a 5^th tank expansion, if needed). The plant tunnels were expanded, all plant mechanical HVAC and separate plant electrical power supply feeds with a main switch – over gear were installed, administrative offices were added and a new plant computer operating system was installed at this time. A Centrifuge for dewatering sludge with all associated piping and pumps were added along with a new building to house it. Three (3) new river pumps were added at the Post Aeration Well (pumping allows discharge to river, even when the river level is higher than the plant’s discharge line). Along the entire length of the plant on the gravel pit quarry side, a retention wall was built and the entire plant was enveloped with 6’ high chain link fence (approx. 6 acres).  

While the 1969 design of the treatment plant was for an average daily flow of 4.0 mgd, it was not capable of treating this amount of flow according to design standards, and for meeting the imposed 1988 effluent permit requirements, especially for ammonia removal. 

Given the present facilities, the flow capacity available for the treatment with respect to the 1988 permit conditions for ammonia would be approximately 2.5 mgd. Completion of the 1988 –1989 plant expansion increased the average capacity to 4.5 mgd.  Since the 1988-1989 Plant upgrade, numerous modifications include adding more equipment onto the flushing water system (recycles the plant effluent discharge water that goes into the river and reduces the costs of using City of Piqua treated water). A building was erected for the grit & grease facility along with installing a new grit classifier and rag press. A dechlorination system was added due to EPA regulating more stringent limits on Chlorine. A new three (3) bay Maintenance Garage plus work area, office/storage loft, and basement for storage has been erected and it houses a new VacCon 2-stage (flush & vacuum) combination sewer maintenance truck, pipeline televising camera truck, sewer maintenance jet flushing truck, and utility pickup truck.

Current Wastewater Treatment

A new plant operating computer system will be installed and completed by fall of 2001. This system will allow for all new plant modifications, any future expansions if necessary, expanded plant maintenance tasking, additional alarming capabilities, sewer collection system information and lift stations statuses, plus more operator flexibility. We are proud to be the host for the Southwest Ohio Water Environment Association Meeting in mid-November 2001.