3102F.22.214.171.124 Underwater Structural Inspection
The underwater inspection shall include all components below deck to the mudline, including the slope and slope protection, in areas immediately surrounding the MOT. The water depth at the berth(s) shall be evaluated, verifying the maximum or loaded draft specified in the MOT's Operations Manual (2 CCR 2385) [2.1].
The underwater structural inspection shall include the Level I, II and III inspection efforts, as shown in Tables 31F-2-2 and 31F-2-3. The underwater inspection levels of effort are described below, per [2.2]:
Level I—Includes a close visual examination, or a tactile examination using large sweeping motions of the hands where visibility is limited. Although the Level I effort is often referred to as a "swim-by" inspection, it must be detailed enough to detect obvious major damage or deterioration due to overstress or other severe deterioration. It should confirm the continuity of the full length of all members and detect undermining or exposure of normally buried elements. A Level I effort may also include limited probing of the substructure and adjacent channel bottom.
Level II—A detailed inspection which requires marine growth removal from a representative sampling of components within the structure. For piles, a 12-inch high band shall be cleaned at designated locations, generally near the low waterline, at the mudline, and midway between the low waterline and the mudline. On a rectangular pile, the marine growth removal should include at least three sides; on an octagon pile, at least six sides; on a round pile, at least three-fourths of the perimeter. On large diameter piles, 3 ft or greater, marine growth removal should be effected on 1 ft by 1 ft areas at four locations approximately equally spaced around the perimeter, at each elevation. On large solid faced elements such as retaining structures, marine growth removal should be effected on 1 ft by 1 ft areas at the three specified elevations. The inspection should also focus on typical areas of weakness, such as attachment points and welds. The Level II effort is intended to detect and identify damaged and deteriorated areas that may be hidden by surface biofouling. The thoroughness of marine growth removal should be governed by what is necessary to discern the condition of the underlying structural material. Removal of all biofouling staining is generally not required.
Level III—A detailed inspection typically involving nondestructive or partially-destructive testing, conducted to detect hidden or interior damage, or to evaluate material homogeneity. Level III testing is generally limited to key structural areas, areas which are suspect or areas which may be representative of the underwater structure.
|I||General visual/tactile inspection to confirm as-built condition and detect severe damage||Extensive corrosion, holes Severe mechanical damage||Major spalling and cracking Severe reinforcement corrosion Broken piles||Major loss of section Broken piles and bracings Severe abrasion or marine borer attack||Permanent deformation Broken piles Major cracking or mechanical damage|
|II||To detect surface defects normally obscured by marine growth||Moderate mechanical damage Corrosion pitting and loss of section||Surface cracking and spalling Rust staining Exposed reinforcing steel and/or prestressing strands||External pile damage due to marine borers Splintered piles Loss of bolts and fasteners Rot or insect infestation||Cracking Delamination Material degradation|
|III||To detect hidden or interior damage, evaluate loss of cross-sectional area, or evaluate material homogeneity||Thickness of material Electrical potentials for cathodic protection||Location of reinforcing steel Beginning of corrosion of reinforcing steel Internal voids Change in material strength||Internal damage due to marine borers (internal voids) Decrease in material strength||N/A|
|LEVEL||SAMPLE SIZE AND METHODOLOGY1|
|Steel||Concrete||Timber||Composite||Slope Protection, Channel Bottom or Mudline-Scour|
|Piles||Bulkheads/Retaining Walls||Piles||Bulkheads/Retaining Walls||Piles||Bulkheads/Retaining Walls||Piles|
|II||Sample Size:||10%||Every 100 LF||10%||Every 100 LF||10%||Every 50 LF||10%||As necessary|
|Method:||Visual: Removal of marine growth in 3 bands||Visual: Removal of marine growth in 1 SF areas||Visual: Removal of marine growth in 3 bands||Visual: Removal of marine growth in 1 SF areas||Visual: Removal of marine growth on 3 bands Measurement: Remaining diameter||Visual: Removal of marine growth in 1 SF areas||Visual: Removal of marine growth in 3 bands|
|III||Sample Size:||5%||Every 200 LF||0%||0%||5%||Every 100 LF||0%||Sonar imaging as necessary|
|Method:||Remaining thickness measurement; electrical potential measurement; corrosion profiling as necessary||Remaining thickness measurement; electrical potential measurement; corrosion profiling as necessary||N/A||N/A||Internal marine borer infestation evaluation||Internal marine borer infestation evaluation|
- The minimum inspection sampling size for small structures shall include at least two components.
LF = Linear Feet; SF = Square Feet; N/A = Not Applicable