RISK ASSESSMENT MATRIX FOR

PORT INFRASTRUCTURE

CHRIS EDWARDSAECOM Inc

Ports have a variety of infrastructure subject to deterioration.The most severe deterioration occurs on the main working assets such as wharves and jetties, principally from chloride attack on steel.

Assets must be kept in good working condition within tight budgets

Asset managers need to prioritise their maintenance programs to be able to plan for future budgets.

Often this is done on the basis of condition alone and ignoring the consequences of loss of service or failure

The AECOM Risk Assessment Deterioration Model (RAM) is a tool that allows assets to be ranked according to their requirement for maintenance based on condition and consequence of loss of service or failure

Penetration Depth

Chlorides (wt % conc)

Ultimate SurfaceChloride Level (Cc)

Critical Chloride Level (Cc)

Diffusion Profile

Difusion Layer (d)Sorption Layer (s)

Cover (c)

Time Dependent Deterioration

Time Dependent Chloride Ingress & Corrosion

Repairs should be timelyThe ranking of assets allows:

• Remediation to be prioritised and scheduled

• Multi-year maintenance budgets to be estimated with confidence

1. Select the Likelihood Rating based on the data points

2. Select the weighting for each data point

3. Calculate the Likelihood Multi Criteria Assessment

4. Select the Consequence Ranking

5. Select the Consequence Weighting

6. Calculate the Consequence Multi Criteria Assessment

Calculate the Severity of Risk

The AECOM RAM is a multi-step process based on Likelihood and Consequences

Likelihood RankingRanking applies for each condition listed below

1 (very good)

2 (minor deterioration)

3 (signifcant deterioation)

4 (severe deterioration but

structurally sound)

5 (severe deteriorationn plus

reduced structural capacity)

Visual condition

As built: No signs of deterioration to concrete cover. How ever, harline cracks may exist. Concrete is intact and sound. No loss of service life

Minor damage: Concrete show s f irst signs of deterioration. No signif icant rust staining. Long service life

Moderate damage: Failure to cover develops from localised to general nature. No significant reduction of structural integrity. Requires treatment w ithin 5 years to maintain durability

Severe Damage: Concrete has signif icantly deteriorated and structural integrity is being affected. Requires treatment w ithin 2 years. Requires removal or strapping of loose materials for safety

Extreme Damage: Major loss of section w ith significantly diminished structural condition and integrity. Requires treatment w ithin 1 year

Carbonation depth results

Very low: Observed carbonation depth < 10% of average concrete cover

Low: Observed carbonation depth 10% - 30% of of average concrete cover

Medium: Observed carbonation depth 40% - 60% of average concrete cover

High: Observed carbonation depth 60% to 80% of average concrete cover

Very High: Observed carbonation depth > 80% of average concrete cover

Chloride ingress results (corrosion threshold 0.06% by weight of concrete)

Very low : Observed chloride concentration (% by w t concrete) < 0.02 at steel reinforcement location

Low : Observed chloride concentration (% by w t concrete) 0.02 to 0.04 at steel reinforcement location

Medium: Observed chloride concentration (% by w t concrete) 0.04 to 0.06 at steel reinforcement location.

High: Observed chloride concentration (% by w t concrete) 0.06 to 0.08

Very High: Observed chloride concentration (% by w t concrete) > 0.08

Aggressive Soil & Groundwater

Benign: dry non-aggressive soilVery low : Non-aggressive soil and groundw ater. Sulfates (expressed as SO4) <5,000 ppm in soil or <1,00 ppm in groundw ater. pH>5.5

Low : Sulfates (expressed as SO4) 5,000-10,000 ppm in soil or 1,000-3,000 ppm in groundw ater. pH 4.5-5.5

Medium : Sulfates (expressed as SO4) 10,000-20,000 ppm in soil or 3,000-10,000 ppm in groundw ater. pH 4-4.5

High: Sulfates (expressed as SO4) >20,000 ppm in soil or >10,000 ppm in groundw ater. pH <4

Estimated loss of structural safety factor ranking

Very low : No loss of reinforcement section estimated

Low: Estimated loss of reinforcement section < 5% original cross section

Medium: Estimated loss of reinforcement section 5% to 10%

High: Estimated loss of reinforcement section 10% to 15% original cross section

Very High: Estimated loss of reinforcement section > 15% original cross section

Estimated remaining service lifetime ranking

Very high: >90% of design life remaining

High: 60% to 80% of design life remaining

Medium: 40% to 60% of design life remaining

Low: 20% to 40% design life remaining

Very low: < 20% design life remaining

Likelihood Weightings

1 Least important2 Low importance3 Medium Importance4 High importance5 Highest importance

Criteria Weighting

Visual condition 3

Exposure environments 5

Carbonation depth results 1

Chloride ingress results (corrosion threshold 0.06% by weight of concrete)

4

Aggressive Soil and Groundwater 3

Estimated loss of structural safety factor ranking 4

Estimated remaining service lifetime ranking 4

Likelihood Multi Criteria Assessment

Pier Cap Deck Soffit Dolphin

Asset ID Visual condition Weighting

Carbonation depth

results Weighting

Chloride ingress results

(corrosion threshold 0.06%

by weight of concrete)

Weighting

Estimated loss of structural safety factor

ranking

Weighting Total Score

Pier Cap 2 3 1 1 4 4 2 4 31

Deck 3 3 1 1 4 4 4 4 42

Dolphin 3 3 1 1 3 4 4 4 38

Consequence Ranking

Consequence Ranking 1 2 3 4 5 6

People Severity 0: No injury or health effect

Severity 1: Slight injury or health effect

Severity 2: Minor injury or health effect

Severity 3: Major injury or health effect

Severity 4: PTD or up to 3 fatalities

Severity 5: More than 3 fatalities

Assets Severity 0: No damage

Severity 1: Slight damage

Severity 2: Minor damage

Severity 3: Moderate damage

Severity 4: Major damage

Severity 5: Massive damage

Environment Severity 0: No effect

Severity 1: Slight effect

Severity 2: Minor effect

Severity 3: Moderate effect

Severity 4: Major effect

Severity 5: Massive effect

Reputation Severity 0: No impact

Severity 1: Slight impact

Severity 2: Minor impact

Severity 3: Moderate impact

Severity 4: Major impact

Severity 5: Massive impact

Consequence Weighting

Criteria Weighting

People 3

Assets 5

Environment 2

Reputation 3

Consequence Multi Criteria Assessment

Asset IDTotal Score

Ranking Weighting Ranking Weighting Ranking Weighting Ranking Weighting

Pier Cap 2 2 3 5 1 1 2 3 26

Deck 3 3 4 5 1 1 3 3 39

Dolphin 2 2 2 5 1 1 5 3 30

User input from Consequence Ranking

Assigned from Consequence Multi Criteria Assessment

People Assets Environment Reputation or Service

Total Score = Likelihood + ConsequenceAsset Likelihood Score Consequence

Score Total Score

Pier Cap 31 26 57 Schedule remediation in 5 -15 years

Deck 42 39 81 Schedule remediation within 2 years

Dolphin 38 30 68 Schedule remediation within 5 years

Action

Consequence Table

Consequence Lower Value Upper Value

Severity 5 100 120Schedule remediation immediately or take the

asset out of service

Severity 4 80 99 Schedule remediation within 2 years

Severity 3 60 79 Schedule remediation within 5 years

Severity 2 40 59 Schedule remediation in 5 -15 years

Severity 1 20 39 On-going montoring on 3-5 yearly schedule

RISK ASSESSMENT MATRIX

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