Publication Summary

A Class II inspection was conducted at the City of Monroe (Monroe) Wastewater Treatment Plant (WWTP) on March 11-13, 1996. The plant was performing marginally during the inspection. Disinfection was inadequate as evidenced by high fecal coliform counts and variable chlorine residuals. Biochemical oxygen demand (BOD5) concentrations in the effluent met weekly average permit limits but slightly exceeded monthly average limits. Total suspended solids (TSS) removal was good. Split samples showed generally good agreement, with the exception of the Monroe influent sample which was weak. There was evidence of degradation of both the Monroe influent and effluent composite samples. A dye study in conjunction with this inspection indicated the possibility of damage to the diffuser from flooding in previous months, but a subsequent dye study by plant personnel during low flow conditions is reported to have shown that the diffuser is intact. Results of the initial dye study suggest that the diffuser is not creating adequate mixing. A dilution study is recommended based on these results and high metals concentrations at the mixing zone boundaries.