SITE INFORMATION AND CORRESPONDENCE_CASE 2

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MEMORANDUM TO: Stan Phillippe DATE: 21 February 1980 FROM: Frank McDermott SUBJECT: CITY OF TRACY SEWAGE TREATMENT FACILITIES On 7 February 1980, I inspected the subject facilities. Inspection was made with Eugene Fryhling, chief plant operator. A number of visits and inspections have been made over the past six months. John Baker, Director of Utilities, has been the contact person. The treatment facilities are rather complex for the volume of wastewater treated (2.8-4.6 MGD). The plant consists of separate primary facilities for domestic and industrial waste followed by an activated bio-filter followed by an activated sludge system. There is a mechanical blower aer- ated pond system for cheese waste and a surface aerated pond equipped with 10 aerators which receives waste from all the systems at one time or another. There are also industrial sludge handling facilities (filter press) and domes- tic sludge and waste activated sludge facilities (digesters). Consequently, the plant requires expert operational and maintenance personnel to meet waste discharge requirements. BOD and Suspended Solids % removal rates over the past year have ranged from 92% to 97%; however, violations for Chlorine Residual , pH, and Coliform Limits have been reported in Effluent Monthly Monitoring Reports, submitted to us for an extended period of time. Mr. Baker believes the automatic chlorination and de-chlorination equipment pacing systems are the cause of Chlorine Residual and Coliform Limit violations. In a letter attached to the November 1979 Monitoring Report, Mr. Baker suggests the water supply may be the contributing factor for low pH values. On my 7 February 1980 inspection I suggested a minor change in the chlorine application at the secondary clarifier effluent mixing zone. At present they have a plastic pipe with one opening. I suggested putting another plastic pipe on the bottom to form a "1" with a number of openings to enhance mixing and contact of clarifier effluent with chlorine. Also if the automatic chlorination de-chlorination system is not operating properly they could go to a manual control system until the automatic system becomes reliable. Mr. Baker thought the pH violations were related to the new water treatment plant going on line. The plant's raw water supply is from the Delta Mendota Canal which has less than half as much alkalinity as the City well water. The water plant was shut down in November and will resume operations this month. The City will continue the investigation to determine the cause of low pH values in the wastewater treatment plant effluent.