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 other measurement methods such as pulse echo ultrasonic thickness
measurement. Deeply pitted metal may even require extensive metal removal
to allow accurate measurements to be taken. As shown in Figure l-4,
priority locations on structures for cleaning are: (1) mean-low-water (MLW)
areas; (2) mud zone areas; and (3) mid-structure zone (between MLW and mud
zone). The areas to be cleaned on piles are specified as bards
approximately ten inches high. The entire perimeter of wood and of steel
piles are usually cleaned and at least half of the perimeter of concrete
piles are cleaned. Weld areas are cleaned to bright metal. On bulkheads
the areas to be cleaned are designated as one-half square foot sections at
two or three elevations for each station. The stations are located at
specified lineal intervals along bulkhead.
1.4.3.2 Cleaning Effort. Experience has shown that the rate of
cleaning varies roughly between a minimum of 30 and a maximum of 70 piles
per day or between 500 and 1500 lineal feet of bulkhead. These figures are
tabulated in Table 1-1. The effort required for cleaning and measuring can
vary widely between inspections because of influencing factors including the
following:
Water visibility, temperature, depth, and current
b. Type facility (pier, quaywall, seawall, bulkhead)
C. Facility size and age
d. Facility usage (inspection interference)
e. Structure materials and coatings
f . Type construction (cross bracing, pile spacing, pile
splices, cellular sheet pile, old repairs)
g. Marine growth (type and quantity)
h. Corrosion
i. Cathodic protection systems (working, overdriven)
Since the cleaning is time-consuming and expensive, determination of the
number of structural elements to be cleaned is important. The number of
structural elements cleaned for any facility will be based on experience
judgments until a scientific method is developed. A general range of the
extent of cleaning required per structure is listed in Table l-l.
1.4.4 Structure Measurements. Determination of the effective
cross-sectional area of sane piles is required to ascertain a reasonable
approximation of the facilities structural load bearing capacity. A variety
of tools and instruments are utilized during both Level II and Level III
efforts to obtain measurements of wood, concrete, and steel piles. Typical
values for the number of measurements/cleaning per day are tabulated in
Table 1-1.
1 . 4 . 4 . 1 L e v e l I I . During Level II efforts, measurements are
Probing wood piles, cross braces, or bulkheads with an icepick is crude, but
fast and inexpensive. Similarly, pounding concrete structures with a hammer
is used to judge by feel and sound how solid or hard the structure is. On
soft concrete, the amount that can be broken away from a structure by a
given number of hammer blows is another crude measure of hardness, but it is
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