Serving Whitman County since 1877
Serving Whitman County since 1877
The Walla Walla District of the U.S. Army Corps of Engineers is upgrading the Lower Granite Lock and Dam Juvenile Fish Facility.
“Fish facility improvements are an important part of the corps’ mission to save salmon and other endangered or threatened species,” said corps spokesman Bruce Henrickson.
The overall upgrade includes “daylighting” the current below-ground juvenile fish transportation piping from the dam to the juvenile fish facility.
“Adult fish migrate upstream via fish ladders to their spawning grounds,” Henrickson said. “Juvenile fish born there migrate downstream, passing over, around and through dams on the river. Juveniles live in the ocean several years, then return upstream as adults to their original spawning grounds, giving birth to new fish.”
“This is about improving juvenile fish survival at Lower Granite, which is currently about 95-96 percent,” Henrickson continued. “Any incremental improvement in juvenile fish survival is significant since millions of juvenile fish pass over, around or through Lower Granite Dam. The ultimate goal is to improve adult fish returns.”
Upgrades to Lower Granite are planned to occur in phases, according to Henrickson. The intent is to improve juvenile fish survival and increase operational reliability of the bypass and collection system. When upgrades are complete, long-term operations and maintenance costs should also be reduced.
In addition to juvenile survival benefits, the corps is also addressing reliability of a system that was built in the early 1970s. The corps has learned much since that time and National Oceanic and Atmospheric Administration Fisheries criteria has evolved largely in part to advancements made in screened bypass systems on the Snake and Columbia rivers. Many of the features that were state of the art in the 1970s no longer comply with NOAA Fisheries criteria for these types of facilities.
The corps is addressing Lower Granite progress to improve fish survival at the dam and longer-term system survival, with the ultimate goal of improving adult fish returns.
The corps previously upgraded its lower Snake River juvenile fish facilities at Ice Harbor Lock and Dam, Lower Monumental Lock and Dam and Little Goose Lock and Dam during the 1980s and 1990s. These improvements contributed to juvenile survival improvement which led to the ultimate goal of improved adult fish returns when those juveniles return from the ocean several years later.
Two preliminary efforts prior to actual construction include:
1. A geotechnical exploration services contract was awarded in May 2013 and was for preliminary effort for planned upgrades and included exploration and drilling to develop a subsurface profile, analysis of foundations, drafting foundation and earthwork specifications, and perform on-site drilled shaft inspection. This work was completed in February 2014.
2. A fish screen slot closure precedes Phase 1a of construction. The fish screen slot closure project contract of approximately $2.7 million was awarded in May 2014 to Engineered Heavy Services LLC of Everett. Work is to permanently close fish screen slots and “Wagner Horn” openings. Wagner Horns are three-foot diameter, corrugate-metal-pipe-lined openings originally used for supplemental attraction flow to the fish screen slots. The fish screen slots will be filled with concrete to provide structural reinforcement where the collection channel wall thickness will be narrowed. Work is specified to be accomplished between Aug. 3, 2014, and March 30, 2015.
Construction of juvenile fish facility upgrades is divided across two phases. Total construction cost for both phases is estimated between $25 million and $100 million. Actual contract amounts are not announced by the corps until after the contract is awarded.
The construction project will daylight about 1,800 feet of underground pressurized pipe by replacing it with an above-ground screen-covered flume about 2,700 feet long, or more than a half mile.
The above-ground flume is longer than the underground pipe because the slope has to maintain minimum depth for fish.
Portions of the flume will be 25 to 30 feet above ground, or several stories tall.
Debris from dam concrete mining to enlarge the fish transportation channel will be about 1,400 cubic yards, or 265 dump truck loads.
The primary dewatering unit is 20-25 feet above ground and is made of about 1,700 cubic yards of concrete, or more than 200 concrete truck loads.
There are more than 65 concrete columns drilled into the ground to support the flume and dewatering unit structure.
Phase 1a contract for $48.3 million was awarded to Garco Construction, Inc., of Spokane, in September 2014. Including options awarded in November 2014, the total contract cost is now $50.276 million. Phase 1a construction c is planned to be completed by Feb. 20, 2017 and includes:
• “Daylighting” the current below-ground juvenile fish transportation piping from the dam to the juvenile fish facility. The current below-ground piping will be moved to above ground.
• Enlarging selected orifices, collection channel and transportation channel.
• Reconfiguring the transportation channel to transition to an exterior elevated concrete channel, which will connect to a new elevated concrete dewatering unit.
• Diverting excess water to new piping and valves for adult fish ladder attraction, emergency facility water supply and fish trap water supply.
• Includes a new elevated 36-inch corrugated metal flume and walkway leading to an elevated passive integrated transponder tag detection system, elevated flume loop and fish pathway to the juvenile fish facility.
Phase 1b is planned to begin in 2016 and be completed in February 2017.
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