As our population continues to grow and the need for new roads, housing and commercial developments increases, finding space to build that doesn’t impair existing wetlands and streams is becoming more difficult. In some cases, impacts are unavoidable, requiring developers to find alternative ways to offset disturbances or destruction. A mitigation bank is a site where resources are restored, established, enhanced or preserved to generate credits, which can then be bought by impactors to compensate for unavoidable losses at a similar ecosystem nearby. In Nashville, Tennessee, KCI produced mitigation bank credits by purchasing rights to a portion of a local farm and restoring the natural resources on the property back to their original state.
Over the years, two streams on Neely’s Bend, a piece of land shaped by the Cumberland River, had been degraded due to past land use disturbances and maintenance of the site for cattle pasture. When assessing the property, our team found that the streams were poorly functioning and degraded with a high density of invasive species dominating the vegetated area nearby. Located within the Nashville Davidson County metro area, this particular site offered our team an opportunity to address many aquatic impacts that are common in the region.
Crews worked with the land owner to identify which portion of the 150-acre cattle farm could be restored and developed a mitigation banking instrument (MBI), a formal agreement between KCI and regulators, that lays out how the site is set up and will be operated. The MBI also helps establish the service area, the geographic vicinity where credits from the project can be applied to mitigate for unavoidable environmental impacts.
Because it was necessary to keep the cows out of the planned conservation area and away from the streams, new fences were installed on the property and two wells were drilled to provide water access. With the cattle removed, the firm’s in-house specialty contracting group, KCI Environmental Technologies and Construction (ETC), began restoring stream function to the system. Crews first cleared portions of the vegetation at the site, which required removing the invasive species that were dominating the area and setting aside the non-invasive woody debris to use later as habitat structures. Our team then moved the streams, which had been straightened, channelized and relocated, back to their original location. Repositioning the channels allowed for a more natural stream flow and integration with a nearby wetland. The new layout was also engineered to minimize the effects of erosion during large storm events.
One of the things that makes this work unique is that our team is full service. From engineering to construction, KCI does almost all the work, which allows us to complete a project very efficiently and also build a strong relationship with the landowner throughout the process.
Adam Spiller, CPESCRegional Practice Leader, Senior Environmental Scientist
Riffles, shallow areas where water runs quickly over rocks, and pools, deep areas with slow moving water, were incorporated into the design to provide a variety of habitat niches. Woody debris, which help to reinforce the streambank, trap organic materials, and provide additional habitats, were added to the channel to mimic natural features of these systems. Additionally, shrubs and cuttings from native trees were planted along the banks of the stream to provide shade and add additional wood and other organics to the stream. Invasive species that come back will be treated in order to give the native species time to become established and thrive.
As part of the project, the owner signed a conservation easement, which protects the restoration area in perpetuity. With construction complete, our team will be responsible for monitoring the site for the next seven years and then long-term management of the site will be conducted by a non-profit land stewardship group. Every year the steward will visit the site and ensure that the easement integrity is being maintained and that the landowner is observing established restrictions.
In total, this project restored more than 4,000 linear feet of channel and generated nearly 3,000 stream mitigation credits, which have all been purchased. Divvied out throughout the life-cycle of the project, credits started to be acquired with the completion of the MBI and continue to be released all the way up until the end of the project. As a private developer, KCI has the ability to set a fee and sell credits on the open market. Pricing the mitigation bank credits is a challenging process, requiring our team to anticipate many cost factors including: design, land, permits, construction, monitoring and maintenance. “There is some risk associated with these projects, because various weather events like storms or droughts could require additional investments needed at the site,” said Spiller. However, with proper planning, the risk process can be calculated, resulting in a profitable and successful project.
In 2017, KCI established speculative mitigation as a strategic initiative to be undertaken by the firm. By 2020, our team will have $5 million of mitigation assets in the ground being monitored for annual release and sale and plans to pursue another $5 million in additional opportunities.