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Post Point Wastewater Treatment Plant

Project Description

The Post Point Wastewater treatment plant in Bellingham, WA was originally built in 1974 to replace the Whatcom Creek treatment plant. The last update done in 1993, provided full secondary treatment and increased contamination removal to 95% before releasing it into Bellingham Bay. Studies showed additional improvements to the existing facility were needed, in order to keep up with the demands of the Community and avoid exceeding State and Federal Standards. Planning for the current improvement project began in 2009.

In 2012, Diamond B was awarded the Mechanical Contract for the Post Point Waste Water Treatment Plant Project. The Improvement project increased capacity of the existing Primary and Secondary Processes. This involved new construction and modifications to the existing structures and systems. Modifications were done to the existing Sludge Basin and new Activated Sludge Basins were added. This included all new Fine Bubble Diffused aeration systems and air distribution piping to these Basins. The complete new system also included a Blower Building that houses (4) new aeration blowers. These Blowers feed over 1000’ of welded 4" – 36" S.S. ALP piping that connects to the new aeration systems. We installed (2) 3000 CFM Natural Gas ASU Units and exhaust fans to keep the blowers working properly. Other rooms that are part of the blower building include an electrical room protected by a sprinkler system that contains a heat pump and a control room containing supply fans and ductwork to maintain temperature.

The new Selector ASB structure included (3) aeration zones and (3) selector zones. New Mechanical equipment at this structure include a new 12” x 6’ Scum Skimmer, (3) new Slow Speed Mixers w/ 30" impellers, 48 Slide gates (54 total on the project), Dewatering pump and Scum Pump. In order to keep up with demands, a new 120’ diameter clarifier was added to provide additional secondary treatment. Other Plant improvements that were done include adding a new Polymer feed station and an Odor control building. To improve odor control; Odor is pulled from the Selector ASB structure to the new Odor Control building through FRP ductwork using two exhaust fans that each have a design exhaust airflow of 9700 CFM. The air is then sent through 2500 cubic feet of Inorganic Biofilter media that is contained in each of the two new Biofilters that make up the new Odor Control Building.

Diamond B installed 1,000’s of feet of pipe, everything from 24" to 72" welded yard piping, ½" to 12" PVC piping, 2" to 36" S.S. piping and 4" to 36" Ductile Iron piping. The Yard Piping installed by DBC spans across the entire project and included all excavation and backfill throughout the existing plant and utilities. DBC pre-fabricated the majority of the piping, supports, ductwork resulting in increased efficiency and productivity.

The Post Point Wastewater Treatment Plant is the City of Bellingham’s only means of treating domestic and industrial wastewater prior to discharging to Bellingham Bay. Diamond B worked closely with the plant manager and the G.C. in scheduling, to make sure the operational capabilities of the treatment plant were not impaired and capacities were not reduced. Some of the major tasks completed that required sequencing and tight scheduling include; 72" ML yard piping replacement, replacement of the 5 Primary Effluent Pumps and replacement of the W/3 & W/4 pumps and associated piping. This was accomplished by our staff’s knowledge and up front planning. The project was completed on time and under budget without causing any unscheduled plant interruptions.

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General Contractor: Mortenson Construction
Owner: City of Bellingham
Start Date: 2012
Completion Date: 2014