Breaking Tradition

White-Tailed Deer Fawn

In my 27 years of working to restore rivers, I have found that the restoration efforts follow a traditional process of investigation, engineering, development of plans and specifications,permitting, bidding, selection and implementation. The three most costly elements of the process are:

– Investigations

– Engineering and

– Implementation

One would think that a significant amount of money would be spent on investigating the size and extent of the impairment that needs restoration. In most cases this is true however there have been times where the Client believes he/she has spent enough money and has enough information to move forward.  More often than not, this decision creates a level of uncertainty that may need address during the implementation phase. Not the best option.

Engineering usually follows the process of developing a restoration design either as a 30%, 60% and 90% design or a 30% to 60% and the remaining design details are finalized by the implementation contractor.  The latter process is called design-build. During the engineering phase, various approaches and technologies are  evaluated and costs are developed which meet the objectives of the project.

The implementation phases is the most costly and is the phase that validates the investigation and engineering efforts. Costs can range from tens of thousands to tens of million dollars depending upon the scope of the project.

Between 2005 through 2008, investigations were performed.  These included probing, core sampling, electro-shocking and categorizing the fishery, Sediment Oxygen Demand studies and flow data acquisition.

Sand Wand TechnologyEngineering phase began with an Engineering Evaluation and Cost Analysis (EE/CA).  The EE/CA basically screens out approaches prior to the full blown design. As part of the EE/CA validation, three Pilot Tests using 3 technologies were implemented. The first technology to be tested was the Sandwand from Streamside Environmental. Essentially the the Sandwand is a man operated piece of equipment that contains a shroud, and injection jet to suspend the fines and a suction port to remove the fines. The result of the Pilot Test was successful however within 5 days the pore spaces between the gravel were filled with organic mud.

The second Pilot Test consisted of utilizing a standard track mounted excavator with a high solids pump mounted at the end of the arm, a grizzly and several screens to sieve the material and geotubes to receive the fines.The entire substrate was pumped to the screening plant, the fines were pumped to the geotubes and the coarse material was placed back into the stream bed and spread by hand. This Pilot Test was a success. The result was a clean gravel substrate however within 3 days the pore spaces in the gravel were clogged with fine silts transported from upstream, again not un-expected. What was un-expected was the time frame.

Based upon the results of the Pilot Tests it was obvious that restoration activities would need to implemented bank to bank as material left behind would be transported downstream to ultimately un-do restoration efforts.

The third Pilot Test was implemented concurrent with the second Pilot Test and consisted of utilizing Streamside Environmental’s Bedload Collector.  We recognized early on that the key to success of our efforts to restore this river would be to control the bed load. We utilized a 24 inch collector and placed it at the bottom edge of a sand bar.

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The bed load collector worked well however the cost for implementation was prohibitive.

In our next post we will provide another example of adaptive management that really allowed us to utilize the dynamic nature of the river to help it restore itself.

Following the EE/CA, the TRUST and the  river restoration contractor decided to move past the design phase and implement an adaptive management approach to implementation and to better stretch the fixed budget. We estimate that by applying the adaptive management approach provided the TRUST a year’s worth of restoration.  More importantly, the approach allows us to take our original EE/CA results and change the approach “on the fly”.

We initiated the restoration activities in November of 2011, the first phase of which we considered a large pilot test. We concluded Phase 3 in November of 2013. We have used adaptive management techniques throughout all phases of work on the Fawn.

An excellent example of using adaptive management, we implemented restoration activities by applying the technology from bank to bank. After restoring approximately 1,000 feet of the river, we assessed how the river adapted to our efforts.  Our evaluation indicated that once the majority of fines were removed, the thalwag re-established itself and the increased energy allowed it to maintain itself. However 7 feet on either side of the thalwag, even though we changed the gradient the clean gravel was quickly clogged with the fine sand bed load.  This validated our original assumptions so we focused our effort on the Thalwag and 7 feet on either side of it.  It is important to note that the source of the fine sand is outside of our control. We have installed several sediment traps but the capture rate is not 100%.