Round Butte Dam, or Selective Water Withdrawal

Round Butte Dam, or Selective Water Withdrawal | 2007-2009

Round Butte Dam is located about 90 miles southeast of Portland, OR on and adjacent to the Warm Springs Reservation. Portland General Electric determined that a selective water withdrawal and fish bypass structure was necessary to ensure the survival of Summer Steelhead and Spring Chinook Salmon in the Upper Deschutes, Metolius and Crooked rivers. Partially due to unusual currents in Lake Billy Chinook, the downstream fish passage facilities constructed in the 1960’s failed to work properly.

The new system will be a 270 foot structure delivered to the site in pieces and assembled in and on the water. Associated Underwater Services will provide the underwater assembly and installation, topside support and underwater survey and inspection.

AUS will be using the long range Falcon “Sea Eye” with sonar capabilites, as pictured above, to guide and monitor the underwater activities. Barnard Construction is the general contractor, assisted by Dix Corporation. The project will take 3 years and involve drilling and grouting 11 piles 50 feet into the lake bottom, 320 feet below the water surface. The steel structure to be installed is made up of 3 parts. A Selective Water Bottom Structure will be submerged to 270 feet deep and attached to the existing powerhouse intake. A floating Selective Water Top Structure will be positioned directly above the Bottom Structure and connected by the 40 foot diameter Vertical Steel Conduit.

This new structure is designed to draw water in a more natural way to attract fish that will then be screened and released downstream on their way to the Pacific Ocean. Pictures of the actual construction shown include an overview of the site and the structure that will be used to lower the Selective Water Bottom Structure. The red iron is the lift barge, the black iron is the permanent pile structure that gets lowered to the bottom.

Brightwater Conveyance System


Brightwater Conveyance System | 2006 – 2010

King County conceived Brightwater as a major improvement to the regional sewerage treatment system in response to rapid population growth in greater Seattle. The project also will bring important environmental benefits, such as controlling untreated overflows into Lake Washington and Puget Sound, and recycling sewage into irrigation water.

The conveyance system portion of this project consists of 13 miles of new bored soft-ground tunnels. The tunnels extend from Woodinville to Puget Sound. These tunnels will connect about 335 miles of existing sewage pipes to a new 36-million-gallons-per-day treatment plant. From the plant, treated wastewater will flow to a new outfall in Puget Sound. Tunnel construction, currently underway, employs four 14- to 20-foot diameter tunnel boring machines, launched and retrieved via deep shafts in glacial tills well below the water table.Topographic conditions along the tunnel alignment range from hills to intervening valleys, resulting in external groundwater pressures that vary greatly, up to a maximum of 7.3 bars. This geologic factor significantly influenced the design of the tunnel lining system—bolted and gasketed precast concrete segments—and type of tunnel boring machines used for excavation—earth pressure balance (EPB) and slurry shield. In fact, the Brightwater Conveyance System marks the first specified use of slurry shield technology in the United States on a competitively-bid contract.

AUS provides diving services for the East Tunnel Contract and performed a sonar survey to determine configuration and dimensions of shaft. Diving services include, but are not limited to, installation of shear key dowels and rebar mat in the IS and IPS shafts

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American Samoa Tafuna Outfall

American Samoa tafuna Outfall | 2007

Due to the extreme ocean conditions at this location, the hold down chains needed to be replaced. Also, new anodes were welded on to protect the steel components of the pipeline.

American Samoa Utulei Outfall

American Samoa Utulei Outfall | 2007

This project required the replacement of a corroded flange backing ring and replacement of three damaged diffuser ports. The repairs were made without shutting down the operation of the sewage treatment plant. Maximum diving depth of – 160′

American Samoa Outfalls

American Samoa Outfalls | 2007-2015

AUS divers spent several months in American Samoa repairing outfalls for both government and private customers. A semi-autonomous agency of the American Samoa Government operates two primary treatment wastewater plants in Utulei and Fogagogo (Tafuna).

The outfalls from these plants service about 8,000 connections and require repair to avoid environmental degradation of American Samoa’s near-water shores. The repairs involve deep water marine construction, surveying, and salvage skills that can only be performed by highly experienced and knowledgeable professional divers. AUS also performed effluent pipeline repairs for tuna canning facilities located on the island.

These pipelines extend from coastal points of origin far into the ocean to depths of 180′ or more. The pictures show our diver welding clamps on one such pipeline. The 36″ clamps are the shiny objects on both sides of the pipeline. The topside photo shows the sometimes turbulent conditions under which the work had to be accomplished.

Divers Find Product Aboard Sunken WWII Tanker

By David Cleary | ENVIRO FOCUS | JUNE 2009 |

In 2007, Associated Underwater Services (AUS) completed a detailed underwater investigation of the USS Chehalis (AOG-48), a WWII-era navel gasoline tanker resting on the bottom of Pago Pago harbor in American Samoa, and discovered a large quantity of product still aboard. Now the company wants the contract to salvage the vintage high-octane aviation fuel, but several obstacles stand in the diving company’s way.

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