BioMicrobics, Inc.

Tundra Tough - Treatment plants specially designed for cold climates provide a solution for two seasonal cabin complexes in Denali, Alaska - Case Study

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Courtesy of BioMicrobics, Inc.

Grizzly Bear Cabins and Campground in Dcnali, Alaska, needed a larger onsite system to handle a major expansion. Across the road, the undersized system for Dcnali River Cabins complex also needed replacement.

Bio-Microbics engineer Reza Shams, Ph.D. helped design engineer Bob Tsigonis, PE., owner of Lifewater Engineering Co. in Fairbanks, to address numerous challenges. Both properties had potable wells and minimal space, ruling out new or replacement drainficlds. Effluent discharging to the Ncnana River had to meet stringent requirements.

'The systems operate May through September, so winter storage was an issue,' says Tsigonis. 'We had to wait until the snow melted and the ground thawed to install them, leaving only a few weeks before the first guests arrived.'

His solution used UxtrcmeSTP sewage treatment plants from Lifcwater Engineering. The units, designed to work on permafrost soils, use bioreactors and BioBarricr flat-plate membrane technology from Bio-Microbics Inc. to produce extremely high-quality effluent for environmentally sensitive areas.

Site Conditions
The systems are above ground on compacted gravel pads. The sites arc less than 500 feet from the Ncnana River and next to Denali National Park.

System Components
Tsigonts designed the Grizzly Bear system to handle 8,000 gpd and the DRC system to handle 24,000 gpd on completion of the complex.

The Grizzly Bearsystem's major components are three 1,750wgallon dualwcompartment plastic septic tanks with BioSTEr pump vault systems from Bio~Microbics,two 1,000wg.1.1I0n dual-compartment plasw tic septic tanks in series with the BioSTEP system, and an 8,000-galIon ExrrcmeS1l' plant with BioBanier membranes in a 40-foO[-long shipping container.

The Denali River Cabins system included a 500wgallon grease interw ceptor, 1,000wgallon plastic tank with BioSTEP system for the launw dry and employee kitchen, an e.xisting 12,000-galion. two-compartment steel septic tank, and a 2'~,000-galIon ExrremcSTP plant in three sidcbywside 40wfoot-long containers.

Both systems have custom-built Welrbased control systems from Ufewater Engineering.

Four microfiltration flat-sheet membrane modules in the bioreactor for the Grizzly Bear system screen ,solid, through pore' of 0.03 to 1.1 microns. A piping system attached to each module transfers permeate to a tank in the control room.

System operation
buildings have 1,750-galIon septic tanks. The fourth has the 1,000-gaI-lon tanks. Wastewater flows by gravity into the primary settling compartment. Effluent passes through angled slots in the sides of two 4-inch-diameter SaniTEE effluent screens, travels up, and passes into the pump chamber through key hole weirs. A water level sensor triggers the pump, transferring effluent through a 1.25-inch PVC pipe to the ExtrcmeSTP plant.

The plant has a two-compartment treatment tank in the rear of the container and a control room in front. The first compartment has a 10,000-gallon bioreactor with three UXOR 1.0 aerators from Bio-Microbics. Regenerative blowers, one per module and one per aerator, send large volumes of air to the submerged aerators and mixing diffusers.