Publication Summary

A limited Class II inspection at Arlington Wastewater Treatment Plant and a concomitant receiving water survey in the Stillaguamish River were conducted by Ecology in September 1986. The plant was operating well and effluent was in compliance with NPDES permit limits. However, split sample analyses indicated the need for a more detailed review of plant laboratory procedures.

A limited Class II inspection at Arlington Wastewater Treatment Plant and a concomitant receiving water survey in the Stillaguamish River were conducted by Ecology in September 1986. The plant was operating well and effluent was in compliance with NPDES permit limits. However, split sample analyses indicated the need for a more detailed review of plant laboratory procedures. The receiving-water-to-effluent dilution ratio at summer low flow was 1400:1. Location of a new outfall line provided excellent dilution and dispersion of effluent, and wastewater discharge had minimal impact on riverine water quality. Unfortunately, the new line was again lost to high flows this past winter and effluent is once more being diverted to a side channel of the river which ponds during low flows. Design of a replacement outfall line should protect against the high flows and unstable sediments characteristic of this portion of the river.