Construction of Stabilization Works
the survey. The survey would include the entire channel in the area of the work, and would
extend far enough upstream and downstream to allow detection of channel migration or bed
scour which might become a threat to the work. Documenting channel bed elevations in the
vicinity of the work is especially critical, since toe scour is often the greatest threat to the
The survey which was used for detailed design will often satisfy this requirement if no
significant channel changes occurred during construction. It can simply be amended to
include details of the work and changes in site conditions during construction.
If a comprehensive survey is beyond the means of the project sponsor, and the stream
is small enough to visually observe future changes that would threaten the work, it may be
sufficient to simply retain the contract plans and specifications, supplemented by photographic
documentation. Ground-level photographs from documented points as the construction
proceeds are useful for contract inspection as well as for future monitoring of the work.
Aerial views are particularly useful for future monitoring of major upstream and downstream
changes. Making the photographs can be the duty of either the contractor, the inspection
personnel, or the designer.
It may be expedient to specify in the contract that the contractor will furnish the
capability to make the as-built survey, and any other surveys required during the course of the
work. Surveys during the course of the work may be required for measurement of quantities,
or for design adjustments if site conditions are unstable. If surveys by the contractor are to
be used for measurement of pay quantities, it is good practice to insure that they are certified
by a professional surveyor. Organizational policy may impose other restrictions as well.
10.3 ENVIRONMENTAL CONSIDERATIONS
The impact of construction operations on environmental quality is often temporary
if the specifications include environmental features and the operations are well-managed.
Since economics will often govern construction operations if left totally to the contractor,
allowable methods of operation, or alternately, methods which are not permissible, should be
clearly specified if environmental aspects are critical. Critical habitat areas, vegetation, or
other sensitive areas not to be disturbed should be identified as being outside the construction
right-of way. Environmental features of the work should be addressed in the specifications
and during construction as thoroughly as engineering features of the work.
Control of surface water and erosion and sedimentation during construction is always
good practice. The design of permanent measures was discussed in 6.4, but other, more
temporary, measures may be a legal requirement for the political jurisdiction in which the
work is being done. Minimizing site disturbance and revegetating areas disturbed by
construction are always desirable measures, and are examples of measures that may be
required by ordinance. Disposal of clearing debris and excavated material should be done in
an environmentally sensitive manner.