Construction of Stabilization Works
that required for the design thickness in order to compensate for the uncertainties of
subaqueous placement.
Likewise, a subaqueous longitudinal toe dike to provide launching stone for toe
protection can be placed at a rate per linear distance along the bank rather than to a specified
height or cross-section shape (for example, 2.1 tons per linear foot of bank in lieu of a peaked
dike 5 feet high).
There are many ways to control the horizontal position of subaqueous placement
operations once shoreline survey points are established. Buoys, driven piles, and moored or
anchored barges are common practices. Sophisticated electronic survey techniques expedite
these controls, and may eliminate the need for stationary markers completely in some cases.
Some proprietary products have specialized procedures and equipment associated
with them. In some cases, those procedures and equipment may be necessary for satisfactory
work; for example, restrictions on permissible height from which to drop stone on engineering
fabric, or the use of frames to lift and place prefabricated mattresses. In other cases, they may
simply expedite the work; for example, metal "templates" for filling gabions. Those which
are necessary should be directed in the specifications. Regarding those procedures and
equipment which merely expedite the work, construction personnel or prospective contractors
should be made aware of them, with choice of use being their prerogative. This may be done
by providing points of contact for manufacturers' representatives in the specifications. Some
manufacturers will provide on-site assistance during construction.
Most aspects of site preparation and restoration are inherent in the topics discussed
previously in this chapter. However, the following points are worthy of separate mention
Subgrade preparation is especially important for armor protection. Debris which
interferes with placement of the armor or filter material must be removed. Freshly graded
slopes are especially susceptible to erosion from surface drainage prior to placement of the
armor, therefore preparing the site to control surface drainage may be critical.
Debris which would hinder proper construction of dikes or retards must be removed.
It can sometimes be placed in a manner to enhance the work by providing additional indirect
protection to the bank.
Restoring access routes to the original condition, but perhaps with additional erosion
control measures, may be appropriate for some projects. For other projects, leaving them
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