Publication Summary

An announced Class II Inspection was conducted June 16-18, 1997 at the City of Ferndale Wastewater Treatment Plant (Ferndale) in Whatcom County, Washington. Included was the analysis for metals of one industrial contributor to the Ferndale collection system: Recomp of Washington, Inc.

An announced Class II Inspection was conducted June 16-18, 1997 at the City of Ferndale Wastewater Treatment Plant (Ferndale) in Whatcom County, Washington. Included was the analysis for metals of one industrial contributor to the Ferndale collection system: Recomp of Washington, Inc.

Moderate reductions in BOD5 and TSS occurred across the treatment plant. Effluent ammonia concentration was relatively high, and exceeded water quality criteria in the whole effluent. Dilution factors can be expected to reduce the impact of discharges to the receiving water. Analysis of the facility′s complete mix aeration cells determined that aeration met minimum oxygenation requirements, but was inadequate for complete mixing. Aeration and detention time in the partial mix cells appear to be controlling algae growth, but may be selecting for nitrifying organisms, increasing the impact of nitrogenous BOD5 in the effluent. Sedimentation in the partial mix cells appears to be negatively impacted by aeration, and it is recommended that aeration be reduced in the partial mix cells.

The 24-hour effluent composite BOD5 concentration exceeded the NPDES permit weekly and monthly average limits, and a 24-hour effluent composite TSS concentration exceeded monthly average limits. Subsequent to the inspection, Ferndale′s installation and operation of a fabric filter system has increased the effectiveness of BOD5 and TSS removal. A portion of the effluent BOD5 may be due to increased nitrogenous BOD5. A tentative Streeter-Phelps analysis of BOD5 in the receiving water indicated that its impact on DO would not cause a violation of water quality standards. Fecal coliform concentrations during the inspection exceeded the permit monthly and violated the NPDES weekly limits, although the inclusion of a new chlorine contact chamber has been effective in correcting this problem. Several metals exceeded the acute and chronic water quality standards in the whole effluent, although when estimated dilution factors are applied, these impacts are likely to be minimal. Several bioassays detected toxicity in the whole effluent, although these effects should also be mitigated by dilution. Recomp′s effluent metal concentrations were all within state permit limits and their contribution to Ferndale effluent was less than 6% for all parameters.