Environmental Engineering Reference
In-Depth Information
Box 10-4. Lesson Learned: Confer with the Designer on Any Design Changes
A geomorphologist/hydrologist designed in-stream fishery habitat improvement structures
and biotechnical stream bank stabilization measures for an urban stream restoration proj-
ect. The plans for the project were approved by a local agency, and the project went to bid.
The contractor proposed a modification in the number and placement of the in-channel
rock structures. The plans were revised without the knowledge of the lead hydrologist,
and the project was constructed during the low-flow period. High flows during the winter
following project construction eroded the stream banks and changed the course of the
channel, resulting in the loss of adjacent parklands. The contractor blamed the erosion on
the project design, and the project designer blamed the damage on the modifications to
the design features. The client was caught in the middle of this finger-pointing.
The project lead and the client learned that, while a contractor may make worth-
while suggestions for the revision of stream restoration plans and specifications, it is
essential to have the key project designers review and approve of these proposed plan
modifications prior to their implementation.
tasks will prove helpful in estimating future project work. The log can also be an important infor-
mation source when producing as-built plans.
Implementation of the Project
Initial activity addresses getting the site ready and then progresses through to the finish of the con-
struction, including documenting exactly what was done.
Removal of Impediments
One of the earliest activities during site preparation is the removal of likely impediments to project
success. Impediments that need to be dealt with include invasive plants, nonnative wildlife, and
sometimes native wildlife, especially if your site is downwind or downstream (fig. 10-5). Unless
prior arrangements have been made, all work must take place within the project limits as identi-
fied on the plot plan.
We discuss strategies for the control or eradication of invasive plants and weeds in chapter 12.
However, at the beginning of the implementation phase, there are additional procedures available
that will not be feasible after construction and installation have begun. For example, you may want
to try solarization as a means of killing the soil seed bank. This technique has limitations but can
be a simple and effective means of control in the correct circumstances (Katan and DeVay 1991;
Lambrecht and D'Amore 2010). You may want to pretreat your site with pre-emergent herbicide
to prevent the growth of invasive plants and other weedy plant species. Some practitioners remove
and discard the top few inches of topsoil in an attempt to rid the restoration area of the seed bank.
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