Publication Summary

An announced Class II Inspection was conducted March 14-16, 1994 at the Port Orchard Sewage Treatment Plant in Kitsap County, Washington. The facility operates a conventional activated sludge treatment system, with chlorine disinfection and anaerobic digestion of sludge. Most effluent results were within the NPDES permit limits.

An announced Class II Inspection was conducted March 14-16, 1994 at the Port Orchard Sewage Treatment Plant in Kitsap County, Washington. The facility operates a conventional activated sludge treatment system, with chlorine disinfection and anaerobic digestion of sludge. Most effluent results were within the NPDES permit limits.

Reduction of BOD5 and TSS across the plant was excellent. NH3-N removal did not occur in the system, and the effluent concentration exceeded Washington State acute and chronic marine water quality standards for ammonia. A mixing zone study is recommended to determine if a mixing zone can be included in the permit. The Port Orchard sample results produced an effluent BOD5 concentration that exceeded the percent-of-influent concentration allowed by permit. One effluent fecal coliform count exceeded the monthly average permit limit. Contact time in the chlorine contact chamber should be evaluated.

Priority pollutant organics and metals were detected in the effluent, but only bis(2-ethylhexyl)- Phthalate and copper exceeded the state water quality standards for marine receiving waters. Wastewater bioassays exhibited significant acute and chronic toxicity. It is recommended that further bioassays be conducted to characterize effluent toxicity and determine effluent impact on marine organisms. Sediment bioassays exhibited acute and chronic toxicity. It is recommended that the impact of outfall deposition on sediment toxicity be evaluated. The need for a pretreatment program to reduce influent metals should also be evaluated.