Reclamation approaches at mine sites and other disturbed areas have changed notably since regulation of surface mines first began with open cut mining laws in the late 1960s. The application of geomorphic reclamation concepts is one of the reclamation approaches that has been gaining wide-spread acceptance in recent years. While some reclamation projects still rely on more traditional reclamation grading techniques, many site owners, operators, and agencies are embracing the benefits associated with contemporary geomorphic reclamation.
What is geomorphic reclamation?
Geomorphic reclamation is a term used to describe a suite of approaches used to develop landforms that mimic native topography. The underlying premise is that native landforms evolve over many years in response to specific climatic and watershed characteristics. Rather than uniform slopes and straight, horizontal terrace alignments that do not perform over the long term and cause reclaimed lands to stand out, geomorphic reclamation is an approach to constructing slopes that generates more complex landforms, reduces flow length, provides natural drainage density, and supports natural slope forms. Other terms such as slope reconstruction and topographic reconstruction may also refer to this type of reclamation approach.
The benefits of geomorphic reclamation
Geomorphic grading designs employ varying slope aspects, concave and convex slopes, and varying channel types to construct reclamation surfaces. This type of grading incorporates multiple channels and ridges that result in numerous, small sub-basins. The more complex topography reduces the length of overland flow and conveys the flows into defined channels, which incorporate natural alignments that increase channel length. Not only does this reclamation approach reduce erosion as compared with more traditional grading concepts, geomorphic reclamation encourages vegetation diversity and is also aesthetically pleasing, blending well with surrounding native topography. If designed and constructed correctly, sites reclaimed through this grading approach can be hard to distinguish from undisturbed lands.
Is geomorphic reclamation right for your site?
Leveraging geomorphic reclamation for mine sites or other disturbed sites is a good option when the end goal is to mimic pre-disturbance conditions, achieve plant diversity, and minimize long-term maintenance and repair. Site design must be appropriate to the site and terrain with consideration of geologic issues, structural integrity, post-reclamation land use, and other pertinent design features discussed with the landowner or operator.
In the past, the primary drawback to geomorphic reclamation was the increased difficulty of designing and constructing complex slopes and drainage patterns as compared to traditional straight or terrace and downdrain grading, or even more simplified landform grading. Fortunately, a CADD-based design package is available to aid in the design of landform grading. This software package, Carlson Natural Regrade with GeoFluvTM (Natural RegradeTM), provides reclamation professionals with a powerful tool for developing geomorphic grading designs.
- Topography reflects natural conditions upon completion
- Channel stability and varied topography reduce erosion
- Geomorphic approach reduces long-term post-reclamation maintenance
- Landform diversity encourages wildlife and plant diversity and habitat
- Regulatory agencies and public stakeholders prefer outcome to traditional grading approaches
- Less reliance and costs associated with structural controls such as rip rap
- May require more time to construct than traditional grading
- May be more expensive than traditional reclamation to construct, especially when using a contractor that is unfamiliar with the approach
- May face reluctance from stakeholders (contractors, regulators, property owners) wary of a new approach
- May not be suitable for all post-reclamation land uses
Best practices for planning and implementing geomorphic reclamation
If you have decided that geomorphic reclamation is the best fit for your site, here are a few things to keep in mind:
- There is no easy button, regardless of the efficiencies provided by modern software. Developing a constructible and functional reclamation surface that mimics an appropriate reference area takes time and multiple iterations, regardless of how powerful the software. Reclamation designs should not and cannot reasonably be developed overnight.
- Geomorphic reclamation is not a standalone solution. While geomorphic reclamation can limit the need for structural controls, reduce erosion, and increase aesthetics, reclamation professionals should complete appropriate analyses to determine whether additional erosion or sediment control measures may be warranted. This is particularly important when tying in with upstream or downstream drainages.
- An accurate survey that extends beyond the proposed grading limits is crucial to developing a stable landform design. Inaccurate surveys of the downstream tie-in elevation or slope of the downstream channel can result in artificial nick points or slope busts that will cause channels to unravel. Additionally, properly tying in geomorphic grading along the perimeter of a project requires a buffer along the perimeter.
- GPS-machine control equipment should be used for constructing geomorphic graded projects. This is particularly important when using Natural RegradeTM, which generates a complex landform.
- Investigating and obtaining characteristics for a reference basin or native landform is critical to developing a functional reclamation landform. The Natural RegradeTM software can be operated using default values, but the resulting design may not be applicable to the project setting. Even though several of the reference characteristics are only used in the software as checks, the process of investigating and noting the characteristics for an appropriate reference area will allow the designer to better refine their grading design to mimic the native landform.
- The quality of geomorphic reclamation projects increases dramatically with designer and contractor experience. Much of this results from understanding the relationship between the complex design contours and the constructed reclamation surface. Be sure to pull together a team that has proven project experience.
Geomorphic reclamation is gaining wider acceptance. Sites completed with this approach are “more natural” looking and typically well received by landowners, agencies, and the public. The ultimate compliment for a reclamation project is to point out the site and have someone ask, “what reclamation?”
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