The Columbia and Wells Dam: How the Mighty River Keeps the Lights On

Bare bulbs in wire cages light Aspect staff’s way down a flight of stairs through a damp concrete passage. One after another, we duck our heads, crawl through a water-tight steel hatch, and emerge in a cavernous chamber lit by a single halogen shop light. Our breath hangs in the cold air, and the sound of water drips from the surrounding shadows. 

Aspect staff make their way down into the basement of Wells Dam

Our guide tips back his hardhat, stares upwards, and explains that we have now descended 150 feet below the surface of the Columbia River. He points with his flashlight towards the middle of the room, to where one of Wells Dam’s Kaplan turbines—a five-bladed spinning top the size of a garbage truck—sits idle. A month from now, when this chamber is again flooded by the river, water will push against those blades, turning a shaft that will activate a generator, create a charge, and produce electricity—enough to power all the houses in the Wenatchee Valley, and then some.

The switchyard and gantry cranes along the top of Wells Dam.

Celebrating the 50th Anniversary of the Nation’s Only Hydrocombine Dam

Fifty miles downstream of Wells Dam, geologists and engineers in Aspect’s Wenatchee office regularly interact with hydropower in our week-to-week work. From evaluating utility district water rights, supporting environmental compliance at fish hatcheries, to helping clients adhere to FERC permit requirements, the influence of dams in the Northwest is far-reaching.

Aspect staff and Douglas PUD engineers explore active retrofitting operations underway for the ten generating units at Wells Dam

When Douglas County PUD offered us an invitation to visit Wells Dam, which celebrated its 50th anniversary earlier this year, Aspect Wenatchee jumped at the opportunity. 

Driving north along Highway 97 on a cold, snowy day in November, we had two things on our mind: what makes Wells unique, and what does it mean for a dam to reach this milestone? Here’s what we learned: 

  • Wells is the only dam in the U.S. designed as a hydrocombine, where the generating units, spillways, fish ladder, and switchyard are vertically stacked (as opposed to horizontally aligned). This gives the dam its compact footprint but presents certain logistical challenges for major maintenance operations. 
  • Like all Columbia River hydropower projects, Wells is a run-of-the-river dam. Reservoirs created by run-of-the-river dams have limited capacity to store water and must respond to fluctuations in seasonal river flows. For dams on the Columbia, this means that most of the available water comes from snowpack and is in greatest supply during the spring. 
  • Generating power at Wells represents a balancing act between storing and spilling water. In addition to coordinating reservoir levels with upstream and downstream dams, operators must forecast and respond to the Methow and Okanogan rivers, which eventually flow into the Columbia, all while complying with a suite of regulations for the protection of fish and wildlife, and fluctuating market demands of the regional grid.
  • Like anything that involves a complex assortment of moving parts, things inside a hydropower project eventually wear out. For Wells, turning 50 means that each of the 10 generating units is reaching its in-service design life. Work is actively underway to completely refurbish, replace, or re-machine the turbine components to extend their service life another 30 to 40 years.

We greatly appreciated the tour and getting an up-close look at one of our region’s hydroelectric projects. Happy 50th Anniversary, Wells—thanks for keeping our lights on!

Aspect's Summer of Sports

For many Aspect staffers, the dry summer months are usually spent out in the field. This season, it was true in more ways than one. Our summer was bookended by sporting events that took us out into the “fields” down the street from our Seattle office. 

In June, the women of Aspect attended a Seattle Mariners matinee game vs. the Philadelphia Phillies at Safeco Field. Adorned in matching tees made especially for the outing, the group indulged in gigantic soft pretzels and other ballpark sundries in between cheering for pitcher Felix Hernandez’s fine outing and the Mariners’ three home runs of the day.

In August, Aspect staff was three rows strong (and several garlic fry orders deep) at Century Link Field as the Seattle Sounders took on the Portland Timbers. Despite both team’s valiant efforts and the ever-present cheers from the crowd, the final score was 1-1. The tie may be frustrating for most fans, but it did make for far less tension between the Seattle and Portland offices at staff meetings the next morning. 

Finally, in September, two Aspect teams (Aspect Earth and Aspect Water) participated in the 2017 Kickball Without Borders Event - a fundraiser organized by the Puget Sound Chapter of Engineers Without Borders for its international projects in Nicaragua, Uganda, and Sierra Leone. We showed up, we tried hard, we had fun, and we exited the tournament early with pulled hammies and bruised egos. There's always next year!   

A big-screen Mariners welcome for Aspect's ladies

The Women of Aspect and their custom tees

The ladies' vantage point for the Mariners' matinee

The Aspect crew catches the last rays of sun at the Sounders match

The Aspect crew catches the last rays of sun at the Sounders match

The Sounders at sunse

Can you spot the Space Needle?

Aspect Earth and Aspect Water kickball teams

Controlled Atmosphere Storage: Keeping Northwest Fruit in Season Year-Round

In the Wenatchee Valley, it’s a common source of pride that Washington is the top producer of apples and pears in the nation. But with so much fruit coming off the trees at roughly the same time each year, have you ever wondered how crisp, crunchy apples and pears are available in the grocery store year-round? Or what enables people across the country—and around the globe—to recognize Washington as the source of the world’s best tree fruit varieties? Enter the technology of controlled atmosphere (CA) storage.

The Wenatchee Valley – the nation’s top apple and pear producer – keeps grocery aisles around the world stocked year-round by using massive, specially constructed warehouses designed to slow the ripening process.

A quick background on tree fruit: as apples and pears ripen, they take in oxygen and release carbon dioxide. Years ago, researchers determined that by limiting oxygen, introducing a little nitrogen, and lowering the temperature, the ripening process can be slowed. To apply this concept at a scale large enough to support Washington’s apple and pear industries, packers build enormous warehouses capable of holding multiple-orchards-worth of fruit within special airtight, refrigerated rooms. This gives shippers the flexibility to releasing fruit incrementally throughout the year, and allows you and I to enjoy a crunchy Honeycrisp apple in the middle of February, months after it was picked.

Building a CA-storage warehouse involves three special considerations: they must be massive, they must be stable, and they must be built quickly. Once fruit is off the trees, it gets hauled in bins that can weigh upwards of 900 pounds when full. Moving these bins requires big equipment (like forklifts and semi-trucks) and efficient storage requires stacking them up to 12 high—that’s a lot of weight! To maintain precise control of the atmosphere within these buildings, the rooms must remain airtight. This means that the foundation and walls must not shift, settle, or crack. Finally, market demands for additional storage capacity often drives the need for new CA warehouses to be built on short notice, with expedited timelines.

One full fruit bin can weigh 900 pounds. Stack those bins 12 feet high, and the need to engineer stable foundations for the warehouses that hold these bins becomes critical.

To meet these rigorous requirements, CA-storage warehouses are typically constructed out of giant precast concrete walls supported by cast-in-place concrete foundations capable of supporting substantial floor loads—up to 1,000 pounds per square foot. Designing for this type of stability requires the expertise of a geotechnical engineer for understanding how soils beneath the building will behave when loaded. By studying the local geology, excavating test pits, and drilling cores, geotechnical engineers can specify how wide and stout the footings and floor slabs should be at a given site.

Aspect geotechnical engineers Nick Szot and Erik Andersen have guided the design of several CA-storage warehouse projects for industry leaders like Blue Bird, Gebbers Farms, McDougall and Sons, and Peshastin Hi-Up. Aspect is proud to be the tree-fruit industry’s local, responsive firm for geotechnical services in the Wenatchee Valley and central Washington, and for our role in bringing Northwest pride to homes across America and around the world.