FIELD DOCUMENTS_CASE 2 - Laserfiche WebLink

Home Browse Search

/ MEMORANDUM OAR 5 1 979 TO: Richard Rose SAN JOAQUIN LOCAL FROM: Frank 0. McDermott HEALTH DISTRICT SUBJECT: City of Tracy, Sewage Treatment Facilities On 14 & 15 December 1978, I made a "C" level inspection of the subject facilities in the company of John Baker, Director of Utilities. This relatively new (operational in 1977) eleven million dollar plant has been plagued by equipment failures, operational inflexibility, and some inadequate process designs. Equipment Failures: Industrial primary clarifier sludge collector, primary digester gas compressor, activated bio-filter forced air fans, stand by generator, secondary clarifier, chlorinator, sulfonator, dry polymer feeder, and numerous pumps and motors. All the above have been out of service for extended periods of time and have caused operational problems with resulting unit and overall plant inefficiency. Inflexibility and High Operational Cost: The secondary system consist of two trains. Each train consist of one activated bio-filter, one 150 h.p, blower, four 200 h.p. blowers, two 125 h.p. mechanical mixers, and two rectangular clarifiers with one traveling bridge. The bridge supports two return sludge pumps and motors, two sludge and scum collector units and one air compressor to operate scum sprays. During the off season (non-canning) one activated bio-filter is not needed to treat the reduced wastewater flow. However, the manufacturer, after last year's bio-filter media collapse, requires a continuous flow over the media at all times necessitating an energy cost without benefit to the treated effluent. The aeration cell blowers have constant speed motors and constant speed mechanical mixers. The BOD loadings to the aeration cells vary, consequently to avoid over- aeration some air is bled off to the atmosphere, anywhere from 30% to 80% is bled off depending on the combination of blowers on line. John Baker, Utilities Direc- tor, estimates between $1600 to $1700 per month of energy is wasted from the blower operation alone. The estimated annual power cost for 1978-79 is $340,000. The manufacturer of the traveling bridge recommends the bridge be operated only when both rectangular final clarifiers are in service. This means 100% final clarifier operation or 50% final clarifier operation. When an expansion joint in the sidewall of one final clarifier failed and a stream about the size of a man's little finger flowed into the adjoining pipe gallery, both clarifiers, of one train, were taken out of service. However, after deter- mining that the reduced detention time in final clarification was aggravating L