The Ohio Environmental Protection Agency (OEPA) has warned the City that the present overflows that occur from the Wastewater Treatment Plant (WWTP) are not acceptable. OEPA has advised the City that they will be put under a compliance schedule to correct overflow problems at the WWTP. OEPA has further advised of their concern of potential effluent violations due to WWTP exceeding flow capacity.
The present WWTP is at capacity today based on dry weather flow. The last major upgrade to the plant was in the early 1970's when secondary treatment process was added. All of the primary treatment facilities date to the 1950's.
Even in dry weather, returning of sludge and decanting cannot be done at the ideal rate without exceeding the weir overflow rates. High overflow rates cause effluent violations.
Due to the continued good maintenance and efforts by the operational staff, equipment has been kept in operational condition well beyond the expected life of the equipment. Mechanical equipment, such as the grit unit, has a general life of 10-20 years but is still in operation almost 50 years later! ( Compare this to a 30-50 year old car.)
As stated, the plant is at capacity and, in some cases, has exceeded the capacity of specific units. Typical design parameters would allow for a 20 year projection with increases of approximately 2.5% per year. Based on operation conditions over the past 9 years, the average daily flow has increased by 28% or 3.1% per year. The present plant needs an increase of a minimum of 50% increase in capacity.
For health, safety, and protection of existing (and proposed) electrical, computer, and laboratory equipment, the laboratory and office must be relocated from above the grit chamber. The grit chamber and head works produce gases that seep into the offices and laboratory located above the headwork's. This will include replacing existing electrical work which has deteriorated due to the gases. A new office/laboratory building is proposed.
Throughout the plant, the safety grating, handrail, and toe plates need replaced or upgraded to bring the City into compliance with OSHA regulations. The deterioration is caused by the length of time exposed to the corrosive atmosphere from raw sewage. OSHA requirements for safety have increased over the last 50 years.
The anaerobic digestion system requires a new boiler, heat exchanger, control panel, wiring, ventilation system, roof, gas collection and gas burning system, safety railing on roof, and new raw sludge pumps.
The present grit equipment needs replaced due to age, dating back to the 1950's.
A ventilation system is needed for all buildings to assist in preventing deterioration from moisture and gases. Presently, most doors and windows have deteriorated due to age and a corrosive atmosphere. These would be replaced with new, energy efficient units.
The present metering has also outlived its life expectancy and needs to be replaced.
A centrifuge unit is now used to dewater the sludge. This unit is outdated and too small. Present technology would be to use a filter press which would be more cost effective. With the use of a filter press, a building or covered storage area may be needed to store dry sludge. The pumping units must also be replaced.
In summary, without an exhausted list of specific items of equipment, there is a need to replace equipment that performed longer than expected and is no longer performing in a manner for cost efficient treatment. The capacity, not only of single units and processes, but also the total plant, needs increased.