The Walla Walla District recently completed dredging work at the confluence of the Snake and Clearwater rivers near Lewiston, Idaho and downstream of Ice Harbor Dam. This is the first project the district has completed using Bipartisan Infrastructure Law funds.
The commitment of Walla Walla District engineers and designers was essential to the overwhelming success of this project. The project delivery team received funding in April 2022, with the goal that dredging would occur during the next in-water work window, which ended March 1, 2023.
The team worked diligently to design the project, collecting incredibly accurate data for contractors, and taking steps to ensure strict environmental standards were met. The effort, which should’ve taken over a year to complete, had a contract awarded by the end of September 2022.
The overall attention to detail resulted in a project that was delivered successfully and $3 million under budget.
Dredging is an important mission for the Walla Walla District, enabling free movement on waterways. This dredging work provided necessary maintenance for the federal navigation channel, which must be maintained at a depth of 14 feet. The Walla Walla District also worked in coordination with stakeholders along the navigation lanes. These stakeholders were able to use the contractor mobilized by the Walla Walla District to perform necessary dredging at their facilities at their expense.
These additional dredging locations included the Clarkston Crane Dock Maintenance Area, the Clarkston Grain Dock Maintenance Area, the Clarkston Recreation Dock Maintenance Area, the Clarkston Cruise Line Dock Maintenance Area, and the Lewiston Grain Dock Maintenance Area.
During the design phase of the project, Walla Walla District engineers used bathymetry data from 2016 and 2021 to provide estimates of how much sediment needed to be removed in the target areas. These estimates were used to inform contractors when putting the project up for bid.
The estimate used for the contract was 218,980 cubic yards of sediment. After work was completed, the final quantity of sediment removed totaled 218,286 cubic yards, a difference of only 0.3%.
Before the actual dredging began, multiple surveys were performed to determine the potential environmental impacts of the project.
“We performed surveys of the areas to be dredged for fall Chinook salmon nests and young lamprey. The water clarity was high, and we were able to determine there would be little to no impacts on these resources from the dredging,” Benjamin Tice, a biologist for the Walla Walla District, said.
All Washington State water quality standards were met throughout the project. The Walla Walla District worked in coordination with multiple agencies to ensure environmental compliance, including the National Marine Fisheries Service, the United States Fish and Wildlife Service, the Washington State Department of Ecology, the Idaho Department of Environmental Quality, the Washington Department of Fish & Wildlife, and the Nez Perce Tribe. By working together with our partners and stakeholders, we can find innovative and effective solutions that balance economic, social and environmental priorities.
The actual dredging began on January 5, and the contractor removed 218,286 cubic yards of sediment in less than 60 days, in 144 scow loads. This sediment was disposed in-water at a site near Bishop Bar. Work was completed before March 1, before the spring fish runs.
“It is often overlooked that responsible stewardship of the natural and non-natural resources we are entrusted with is an intrinsic part of our commitment as engineers and designers. Good design serves to ensure proper use of the resources we have been blessed with to meet the needs of society while safeguarding those resources for continued use. I believe this project serves as a good demonstration that shows we can effectively utilize our natural resources responsibly and exercise good stewardship to preserve those resources for future generations,” Frank Wachob, a civil engineer for the Walla Walla District, said.
The last dredging work done in these areas was performed in 2015, eight years ago. Historically, dredging for channel maintenance has been conducted every three to seven years.
The Walla Walla District will continue to invest in the best technology and practices to ensure the highest quality services. The district has many more projects funded by the Bipartisan Infrastructure Law, including the ecosystem restoration of Clover Island. The ribbon-cutting ceremony for Clover Island will be held on May 12.
Ice Harbor Lock and Dam boasts some of the most cutting-edge hydropower technology in the world. Two advanced technology turbines currently sit in the powerhouse, with a third one on the way. These new turbines were designed to improve fish passage and generate electricity more efficiently.
However, the story of Ice Harbor’s powerhouse begins, not with cutting-edge technology, but with a mechanical failure.
In January 1962, there was only one generator unit installed at the newly built dam. Then, during a critical load rejection test on January 5, the sudden loss of load caused the turbine to spin too fast. The blades of the turbine shifted outward, colliding with the discharge ring that encircled them.
The resulting damage put the unit out of commission for an entire year.
The birth of the lower Snake River dams
At the beginning of the 1900s, there was a drive to harness the rivers of the Northwest for navigation and hydropower. To this end, the River and Harbor Act of 1916 directed the examination of the lower Snake River for a series of locks and dams.
Multiple studies were performed in the region, and in June of 1938, House Document 704, 75th Congress, 3rd Session, was published. This report recommended, among other things, the construction of four dams on the lower Snake River.
However, it was not until 1945 when the River and Harbor Act authorized those four dams to be built. These dams would provide the region with navigation, irrigation access, and most importantly, hydropower.
Hydropower is a clean, renewable and reliable energy source. As Congress authorized the construction of hydropower dams in the Northwest, they saw the potential to create abundant and affordable energy in the region. However, setting up the federal hydropower system was not without red tape.
When Bonneville Dam, the first dam on the lower Columbia River, was being constructed, there were debates about whether the U.S. Army Corps of Engineers could market the electricity its dams produced. These debates resulted in the Bonneville Power Administration being created in 1937. USACE would operate and maintain the dams they constructed; however, BPA would handle the distribution of the hydropower.
Today, BPA is the federal agency responsible for marketing electricity produced by 31 federal dams in the Northwest that are operated by USACE and the Bureau of Reclamation. They also market power from one nonfederal nuclear plant and several small nonfederal power plants.
USACE is now the single largest owner and operator of hydropower in the U.S., with 24% of the nation's hydropower generating capacity. The dams on the Columbia and Snake rivers generate 63% of USACE hydropower.
The first and furthest downriver of the four lower Snake River dams was named Ice Harbor, a reference to a nearby ice-free cove used by boat operators in the late 1800s.
Planning for Ice Harbor Lock and Dam began in early 1948 with the USACE Portland District. Then, in November 1948, USACE established the Walla Walla District, and the Ice Harbor project was handed over, along with jurisdiction over the three remaining lower Snake River dams.
But before construction could begin, the project was put on hold. In June of 1950, the Korean War began, and President Harry Truman put a freeze against new government construction projects. Ice Harbor Lock and Dam would remain in limbo for five years.
While the project was stuck in planning, engineers continued to tweak its design. These changes included increasing the number of turbine units in the powerhouse from three, to five, to six. The individual generator capacity for each turbine unit was also increased, from 65,000 kw to 90,000 kw.
These decisions would influence the designs of the future lower Snake River dams, whose powerhouses would come to exceed Ice Harbor’s in capacity.
Keeping the lights on
Construction finally began in early 1956, and by 1961 the first generator unit was installed. It produced commercial power for the first time on December 18, 1961.
It was a promising beginning, however a mechanical failure during critical load rejection tests in January 1962 resulted in extensive damage to the turbine. The entire generator unit had to be disassembled and was out of commission until February of the following year.
Despite the setback, two more generator units were installed and began generating power in February 1962. While the construction plans called for six generator units in the powerhouse, only three were to be installed right away. The plan was to install the remaining three sometime in 1980, as the region’s need for power generation increased.
However, the population of the Pacific Northwest grew much quicker than expected, and the oil embargo of 1973 led to an energy crisis across the United States. BPA realized the power supply in the region would soon be exceeded by increasing demands. Something needed to be done.
The Walla Walla District responded to this issue by rushing to double the generating capacity of Ice Harbor and the other three dams on the lower Snake River. Each of the four dams would go from three generator units to six. Ice Harbor’s last three units were installed in 1976. The last unit on the lower Snake River was installed in 1979 at Lower Monumental Lock and Dam.
These efforts by the Walla Walla District helped prevent a detrimental power shortage in the region. Ice Harbor and the lower Snake River dams remain a vital part of the power grid to this day.
Balancing the grid
As the water passes through the dam’s powerhouse, it falls from the upstream level behind the dam to a lower downstream level. This water, moving with tremendous force, is guided down to the turbine.
As it strikes the blades of the turbine, the water turns the turbine like a propeller. The turning turbine spins coils of wires inside a large generator mounted above it, converting the mechanical energy of falling water into electrical energy. Transmission lines then carry the electricity to homes and businesses.
The power grid is a system of power plants, like hydropower dams, and transmission lines. To function properly, the grid must produce enough electricity to meet the demand. If there is not enough electricity to meet the demand, not everyone will be able to receive power, leading to rolling blackouts. If demand suddenly drops, and too much electricity is being produced, generators are shut down to prevent damages. Ice Harbor’s failed generator unit in 1962 is a good example of what can happen when energy supply exceeds demand.
This means the power grid must be flexible and responsive. It must be able to rise and meet heavier loads, and it must be able to slow down to avoid damaging itself.
In the Pacific Northwest, hydropower provides about 60% of the region’s power needs.
Unlike nonrenewable energy sources that use up their fuel, such as coal and natural gas, the water used to generate hydropower is used over and over. Water flowing down the river evaporates into clouds, falls as rain, and flows down the river to be used again.
Today, the Pacific Northwest also uses wind and solar power to generate electricity. On their own, wind and solar cannot balance the power grid. The amount of electricity they produce rises and falls based on the amount of wind or sunlight available. This is problematic because the grid needs electricity production to rise and fall in response to energy demand, not weather.
Because wind and solar fluctuate, the power grid needs an additional energy source, one that can pick up the slack when wind and solar aren’t available. Traditional sources like coal and natural gas can fill this need, but they cannot ramp up energy production fast enough to cover sudden drops in production by other power plants.
Hydropower, on the other hand, can start up quickly. In a hydropower dam, a turbine unit can go from producing 0 to 100 megawatts in about 2 minutes. It’s this kind of flexibility that allows the power grid to incorporate energy sources like wind and solar, by picking up hydropower during their sudden drops in power generation.
In 1995, the Turbine Survival Program, funded by BPA, began seeking ways to improve hydropower turbine units with regards to fish passage. The program assessed what factors led to injuries of fish passing through a turbine unit. This data allowed engineers to design new turbines that would be safer for fish.
The Walla Walla District awarded a contract to Voith Hydro in 2010 to design and supply one fixed blade turbine and two adjustable blade turbines at Ice Harbor. A contract was awarded to Voith Hydro in 2016 to install the three new turbines.
The first of the three new turbines, the fixed blade, was installed in the Ice Harbor powerhouse on June 8, 2018. The first adjustable blade turbine currently being installed.
These turbines are the first of their kind, designed by USACE personnel and Voith Hydro. The turbines were designed to improve fish passage. They also include greaseless components and improved seal technology to reduce incidents of oil leaking into the river. On top of being better environmentally, projections indicate the new turbines are 3% to 4% more efficient at generating electricity.
Living on the lower Snake
Ice Harbor Lock and Dam was dedicated on May 9, 1962, the first of four dams on the lower Snake River. It was a big event, with the ceremony being performed by Vice President Lyndon B. Johnson.
Today, Ice Harbor is 61 years old, and the Walla Walla District is celebrating its 75th Anniversary on November 1, 2023.
A lot has happened since the Ice Harbor powerhouse came online. Between 2017 and 2021, Ice Harbor has generated an average of 1,655,485 megawatt hours every year for the region. On its own, it has the capacity to generate enough power for all Eastern Washington, except for Spokane.
And its capacity is not stagnant. The Walla Walla District is always leaning forward to makes its projects better. The third modern turbine planned for Ice Harbor will be installed sometime in the next few years, representing another step towards hydropower that is more efficient and safer for fish.
Both Ice Harbor and the Walla Walla District will continue moving forward, innovating and growing in order to serve the region and the nation.