Stream morphology and understanding all of the many mechanisms that dictate how streams move and grow overtime is vital when working on projects where surface water is present. On sites where there has been an environmental impact, depending on the contaminant, there will already be many challenges. Sites that have surface water, whether that be a creek bed running through the project area, or perhaps pooling water in the spring as the snow melts, are a challenge onto themselves.
Many of the contaminants we've experienced have an innate desire to spread and become diluted when in contact with water. In situations when contaminants encounter surface water, the time it takes for a relatively small, impacted area of a concentrated contaminate to turn into a more diluted but still severely impacted wide area, is short. Unless there is some physical or geological barrier in the landscape preventing the flow of surface water, that contaminant will move. In the example of a contaminate suspended in moving water, it has the potential to travel miles with devastating effect. In situations such as those where the contaminant has spread over such a wide area within the surface water, the risk grows exponentially of that contaminant being introduced into the groundwater or the aquifer of the area, and that is incredibly difficult to remediate. Traditional responses to situations such as these are to excavate a large portion of the area and to create depressed, sunken pools to wash the affected area into and recover from. While this improves the concentration of the impact somewhat, it ultimately further dilutes and spreads that contaminant, as well as relies on unnecessary invasive disturbances to the streambed and surrounding landscape. That's not to say that excavation should never be considered, because in many situations it is necessary to a degree, but Genus aims to use it as minimally as possible as the project allows. Instead, we incorporate information from a wide range of specialties so that we can replicate, to the best of our ability, the balancing effect that nature does on its own, in a shorter time.
A product that's often used to restrict the flow of water on sites are large HDPE liners that are stretched the width of the stream bed, from top to bottom. While these serve their purpose of containing the contaminant and allowing water to pool in an area to better test and reclaim from, they are an impenetrable barrier. An alternative to this that we developed and have utilized on many projects since, has been to create a series of cobble structures that still slow the water in areas that we need it to, that create a variety of water depths in areas that we need it to, that still allow for testing and retrieval, but also allow for all of the organic life that begins to come back into the stream over the course of a projects duration to be able to navigate up and downstream.
This starts with things like the macroinvertebrates that are common in freshwater streams, crawdads, and small amphibians. Because of the cobble structures that we put into place, those creatures have the ability able to repopulate an area that would have been otherwise blocked off. The growth of that tier of the food chain, in our experience, almost always brings larger animals and mammals back to the area as well. To see the wildlife return to a site where remediation is ongoing is always inspiring to see, and we use it as an indicator that while the project may not be done, steps are being made in the right direction and those changes can be felt and seen in real time.
All too often much of the restoration efforts of clean-up sites don't begin until much of the remediation tasks are completed. That is where much of the expertise and knowledge accessible today about stream morphology is utilized, in habitat restoration. That, unfortunately, can take years. Some projects may never be ‘clean’ enough to begin restoration by traditional methodology. Our response is unique in that remediation and restoration are both considered and worked towards from day one. By understanding the many complexities of how streams and creeks function from a restoration outlook, we can then use that knowledge during our remediation process by being more aware of where impacts are most likely to settle, where salts and minerals are most likely to deposit, to aid in understanding in how wildlife may be interacting with the streambed and how their presence can influence remediation efforts. Transplanting different plant species into areas that would have otherwise been left to be replanted at a much later date that are more tolerant of the conditions of the stream that exists at the time of the cleanup creates an opportunity for that area to be replanted much sooner than it would have otherwise been. Introducing those organic elements back into these affected areas benefits the overall remediation timeline, as well as jumpstarts restoration efforts.
Not understanding how these processes ebb and flow, how surface water can influence surrounding landscapes and the organic life living in and around it, can lead to preventable adverse environmental outcomes. Nature is resilient. The mechanism that is always moving towards balance is one of the most powerful and effective tools that we have in remediation, and there is a millennia of success stories to show that.