HESCO Flood Barriers are Being Deployed in Juneau, Alaska against a “Glacial Outburst” that recently flooded over 300 homes!
When you hear that HESCO Flood Barriers are being deployed in Juneau, Alaska against a “Glacial Outburst”, you might immediately wonder, “What is a Glacial Outburst?” Flood Defense Group has built flood barriers throughout the USA against several different types of flooding, but a ‘Glacial Outburst’ is an impressive display of nature that we have not experienced previously within the continental USA.
As a result of this unprecedented event, the US Army Corps of Engineers is assisting to combat this new threat by supplying several miles worth of HESCO Floodline barriers.
These flood barriers are uniquely suited for large scale flood defense deployments and working within the challenging environment along the banks of the Mendenhall River. They are actively being deployed under the watchful eye of the City and Borough of Juneau to protect the city’s infrastructure and residential population from this extremely powerful force of nature. Imagine living in the picturesque, forested, coastal mountain Town of Juneau, located along the Mendenhall River which is fed by runoff from the Mendenhall Glacier that is only located a few miles up the road. The Mendenhall River has a fairly low and consistent flow of water for the 6 miles it takes to go from the glacier to the sea, until the glacial outburst occurred. On August 6th, 2024, the Mendenhall River rose nearly 16’ over the course of about 12 hours, overtopped the riverbank, and caused
the flooding of over 300 homes and catastrophic erosion as an estimated 16 billion gallons of water trapped under the glacier was released in less than a 48-hour period. The huge volume of water came rushing down the restrictive canyon of the Mendenhall River which has been carved out by thousands of years of glacial activity. Along the way, the torrent of water caused huge evergreen trees that stood over 200’ tall to fall down like dominos as the soil below them was eroded and lost to the river. This created projectiles within the river that caused further damage to structures, fences, and anything that stood in their way. It was an awe-inspiring example of Mother Nature’s fury.
Here is the bigger problem. This event keeps happening and it is getting worse!! Under the Mendenhall Glacier, there is a basin (like a lake) under the ice known as Suicide Basin. During the winter months, freezing conditions cause the basin to freeze shut as the glacial ice forms an impenetrable bond to the rocky terrain. As temperatures rise and the glacier melts, this basin under the ice will continue to fill up with glacial runoff. This causes an observable rise of the glacial ice over this basin as the lake below the glacier fills with water. As the summer goes by and temperatures warm up, glacial runoff becomes greater in volume and sun light radiates heat against the rocky surroundings causing the rock to warm and the glacial ice to lose its bond to the ground. This results in the glacial ice floating upward at the mouth of this subglacial lake and releases billions of gallons of water to snake its way under the remaining glacier for about a mile before dumping into Mendenhall Lake which feeds Mendenhall River.
This glacial outburst does not happen every year but there is a trend of this problem getting worse. In 2024, the river peak set a record 15.99’ of water depth which broke last year’s record by nearly 1’!! This event is trending in a bad direction.
There are many reasons/theories that are being attributed to the growing threat of glacial outbursts which puts Juneau in harm’s way, but one factor can certainly be attributed to the receding glacier itself. In the past, the glacier was much longer which resulted in the water being released from Suicide Basin to travel further under the ice. This would certainly help regulate the release of water from Suicide Basin but now that the glacier is quickly receding. It is now easier/faster for the flow of water to make its way into the Mendenhall River and subsequently the City and Borough of Juneau because there is little glacial ice left to slow the water down as it makes its way to Juneau. As the glacier continues to recede, this problem will only get worse and additionally, there are basins further up the glacier which are even bigger and subject to glacial outbursts. Juneau needs a solution, and they need it fast!
In this situation, the HESCO Barrier was clearly the best flood barrier for the job for a variety of reasons.
Potential Depth of the Flood Waters
One huge feature that makes the
HESCO flood barrier special is that it can be stacked to achieve significant heights. This is great because if the flood threat is perceived to be higher, you can simply stack these flood barriers higher. Most other flood barriers in the industry do not allow the option for stacking and/or the stability of the HESCO barrier when being stacked to achieve significant heights for flood protection.
Catastrophic Debris Impact Threats from 200’ Tall Trees
One reason HESCO is a popular flood barrier in forest fire burn scar areas is because of its ability to absorb impacts from debris flows that commonly occur after the fire. Debris flows are among the most dangerous types of flooding. We believe this type of floodwater is heavier and exerts more pressure than ‘normal floodwater’ because it is more like a liquid soup of dirt, sand, rocks, water, and huge trees being sent downstream like projectiles waiting to cause havoc. The geography of forest fire burn scar areas is largely within mountainous terrain which means it is flowing fast. Really Fast! This creates additional dangers from ramming trees, rolling rocks as big as cars, and huge pressures exerted from the floodwater itself.
HESCO barriers have been extensively tested within laboratories and ‘real world’ applications against threats within both the civil and military industries. These threats go well beyond debris impact within a flood situation to ballistic threats like car bombs, ramming dump trucks, bulk explosive charges, rockets, artillery, and more. HESCO barriers have the biggest reputation and resume in the industry for performance in stopping all of these threats!!
Challenging Terrain for Flood Barriers
The versatility of HESCO is another reason it was chosen for the challenging terrain encountered along the Mendenhall River. This flood barrier can be stacked to achieve additional height and made thicker for additional mass where floodwaters are most threatening. It can be modified to be thinner for tight areas or to allow one-way drains to be plumbed through while easily being able to snake this product through the curvy, forest environment of Juneau. The terrain itself that this flood barrier had to work through makes the vast majority of flood barriers on the market unsuitable for this difficult topography.
Years of Protection Required
HESCO is a temporary flood barrier that may be in place for a number of years before a long-term solution can be identified and implemented. Although the manufacturer of this product states a 5 year design life for product liability purposes, we have seen this product installed in locations where it has been in place for upwards of 10-15 years and still functioning extremely well. Simple steps can be taken to make this product perform much longer which could include painting it, stucco it, vegetate it, or otherwise shade it. In this case, a flood barrier that could be in place for a number of years while retaining its full function without degradation was required.
Economically Friendly
As a total bonus, HESCO is also one of the most economical flood barrier options on the market when you compare the cost per linear foot to other designs available. It is the unique attributes of design, price, simple construction, effectiveness, and history of performance that make this flood barrier the most popular flood barrier for large scale governmental and commercial applications like the banks of the Mendenhall River in Juneau.
The installation of HESCO flood barriers along the Mendenhall River are expected to be completed within the month of May 2025 and the residents of Juneau can sleep a little easier knowing that intermediate protection is in place while a long-term solution is studied, identified, designed, approved, and implemented.
The installation of HESCO flood barriers along the Mendenhall River are expected to be completed within the month of May 2025 and the residents of Juneau can sleep a little easier knowing that intermediate protection is in place while a long-term solution is studied, identified, designed, approved, and implemented. That process will likely take years and, in the meantime, the HESCO flood barrier remains in place to protect the residents of the City and Borough of Juneau.
If you need flood barriers to protect yourself from debris flows and/or redirect flash flooding, we have the HESCO flood barrier in stock and available for purchase in the USA!
Flood Defense Group
1-208-585-1815
info@flooddefensegroup.com
