HomeMy WebLinkAbout6620; STORM DRAIN CONDITION ASSESSMENT PROGRAM; STORM DRAIN ASSET BUSINESS RISK EXPOSURE RE CALIBRATION; 2018-09-01
Storm Drain Asset Business Risk Exposure Recalibration Page 1
20069-001
September 19, 2018
To: Danny Zimny, City of Carlsbad
From: Sean Pour, Hazen
Dawn Guendert, Hazen
Janet Ortega, Hazen
Peace Maari, Hazen,
Arthur Moncrieffe, Hazen
cc: Kevin Alexander, Hazen
Tama Snow, Hazen
Storm Drain Asset Business Risk Exposure
Recalibration
City of Carlsbad
Storm Drain Asset Business Risk Exposure Recalibration Page 2
Table of Contents
1. Introduction .............................................................................................................. 3
1.1 Background .............................................................................................................................. 3
1.2 Purpose .................................................................................................................................... 4
2. Probability of Failure ................................................................................................ 4
2.1 Condition-Based Probability of Failure ..................................................................................... 4
2.2 Age-Based Probability of Failure .............................................................................................. 6
2.3 Results ..................................................................................................................................... 6
3. Consequence of Failure ........................................................................................... 9
3.1 Zoning / Landuse / Facilities ................................................................................................... 10
3.2 Traffic Impact ......................................................................................................................... 12
3.3 Environmentally Sensitive Areas ............................................................................................ 14
3.4 Special Flood Hazard Area CoF ............................................................................................. 16
3.5 Unit Type CoF ........................................................................................................................ 18
3.6 Unit Sub-Type / Size CoF ....................................................................................................... 18
3.6.1 Unit Subtype / Size CoF Override .............................................................................. 18
3.7 Total CoF ............................................................................................................................... 20
3.7.1 Total CoF Override .................................................................................................... 20
3.8 Final CoF Results ................................................................................................................... 20
3.9 CoF Flowchart ........................................................................................................................ 23
4. Business Risk Exposure (BRE) Results ................................................................. 26
5. Summary and Recommendations .......................................................................... 35
Storm Drain Asset Business Risk Exposure Recalibration Page 3
1. Introduction
1.1 Background
The City of Carlsbad (City) is facing some challenges common amongst water and wastewater utilities
across the country. Rising costs, aging infrastructure, increasing regulatory requirements, environmental
complexities, and a changing work force are just some of the challenges the City’s Storm Drain Group
wants to address through updating their existing Asset Management Plan. The purpose of the Plan is to
prioritize condition assessment efforts, reduce risk, and increase reliability of the City’s storm drain
system. Hazen was tasked by the City to recalibrate the Business Risk Exposure (BRE) component of the
Storm Drain Asset Management Plan that consists of a condition-based Probability of Failure (PoF) and
an updated Consequence of Failure (CoF) framework. Business Risk Exposure scores were calculated for
the northwest quadrant of the City’s service area which was agreed upon by Hazen and the City as the
Pilot Area. Figure 1-1 demonstrates the location of the Pilot Area within the City boundary used for this
study.
Figure 1-1: Pilot Area Used for BRE Recalibration
Storm Drain Asset Business Risk Exposure Recalibration Page 4
1.2 Purpose
This document summarizes the following analyses for assets located in the Pilot Area:
Probability of Failure
o Summary of CCTV data and conversion to Probability of Failure (PoF) scores
o Summary of PoF scores for all assets, including age- and condition-based
Consequence of Failure
o Updated Consequence of Failure framework (CoF)
o CoF flow chart
o Summary of Total CoF scores for all storm drain assets
Business Risk Exposure
o Summary of Business Risk Exposure (BRE) scores
o Visual summary of BRE scores
2. Probability of Failure
Probability of Failure measures an asset’s likelihood of failure. Methods of calculating PoF for all storm
drain assets differed based on asset type and availability of CCTV data. The following PoF calculation
methods were applied to storm drain assets:
Gravity Mains
o Condition-based if CCTV data is available
o Age-based if CCTV data is not available
Discharge Structures, Inlet Structures, Detention Basins, Open Drains, Junctions, Cleanouts
o Age-Based
2.1 Condition-Based Probability of Failure
PoF for gravity mains with CCTV data were calculated using the National Association of Sewer System
Companies (NASSCO) Pipeline Assessment Certification Program (PACP) defect code conversion
method (see Appendix A). Structural defect codes recorded in CCTV observations were converted into
Storm Drain Asset Business Risk Exposure Recalibration Page 5
condition grades that were then calculated into an overall rating. Table 2-1 shows some of the logics used
to convert structural PACP codes to condition grades.
Table 2-1: Logics to Convert Structural PACP Codes to Condition Grades
PACP Code Meaning Code Type Condition Grade
B Broken Structural 5
CL Heavy roots in crack/joint Structural 2
CM Cracks Multiple Structural 3
CS Radial Hairline Crack Structural 2
D Endentation on pipe Structural 4
FC Cracked Joint Severe Structural 3
FL Fracture Longitudinal Structural 3
FM Longitudinal Severe Structural 4
FS Radial Moderate Crack Structural 3
H Hole Structural 5
HSV Hole Soil Visible Structural 5
Number of defects, length of defects and the condition grade were referenced to calculate the overall
rating, as seen in Table 2-2.
Table 2-2 An Example of Pipeline Overall Rating Components
Condition Grade Number of Defects Segment Grade
5 6 30
4 0 0
3 2 6
2 4 8
1 0 0
Total 12 44
Once the overall rating was determined, the Pipe Rating Index (RI) was calculated using the formula
shown in Figure 2-1.
𝑅𝐼=Overall Rating
Total number of defects
Figure 2-1: Pipe Rating Index Formula
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Pipe rating indexes were then compared to the maximum assigned condition score of a pipe segment. If
the maximum condition score was greater, the pipe segment was assigned that score and vice versa.
2.2 Age-Based Probability of Failure
PoF for gravity mains without CCTV data and all other storm drain asset classes were determined using
age and useful life. The age of the assets were divided by its corresponding useful life to calculate the PoF
percentage. The formula used for this calculation is shown in Figure 2-2 below.
Figure 2-2: Formula Used to Calculate Age-Based Probability of Failure
Useful lives used to determine Probability of Failure can be found in Appendix B.
2.3 Results
Figure 2-3, Figure 2-4 and Table 2-3 demonstrate PoF results for gravity mains, and all storm drain
assets.
Table 2-3: PoF Results for Gravity Mains
PoF Count % of System
0 – 30% 701 46%
30 – 60% 711 47%
60 – 90% 67 4%
90 – 100% 30 3%
Total 1,509 100%
Age
Based PoF
Age /
Useful Life
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Figure 2-3: PoF Results for Gravity Main
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Figure 2-4: PoF Summary for All Storm Drain Assets
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3. Consequence of Failure
Consequence of Failure (CoF) evaluates the direct and indirect impacts of asset failure against triple
bottom line factors (Environment, Economic, and Social). CoF for the Pilot Area was calculated by
assigning updated weights to updated CoF criteria proposed by Hazen and approved by the City (see
Table 3-1 and Table 3-2.
Table 3-1: CoF Criteria and Weighting for Gravity Mains, Discharge Structures, Inlet Structures and Detention
Basins
Table 3-2: CoF Criteria and Weighting for Open Drains, Junctions, Cleanouts and Outfalls
Open Drains, Junctions, Clean Outs, Outfalls
Zoning / Land
Use / Facilities
Traffic
Impact
Environmentally
Sensitive Areas
Special Flood
Hazard Area Unit Type Unit Sub -
Type
20% 30% 10% 5% 20% 15%
The remainder of this section will briefly describe each criteria and weighting and the final results. A
CoF weighting and criteria flow chart was created to visually represent Table 3-1 and Table 3-2 and assist
in future application of CoF logics in Innovyze InfoMaster software.
Gravity Mains, Discharge Structures, Inlet Structures, Detention Basins
Zoning /
Land Use /
Facilities
Traffic
Impact Environmentally
Sensitive Areas Special Flood
Hazard Area Unit Type Size
20% 30% 10% 5% 20% 15%
Storm Drain Asset Business Risk Exposure Recalibration Page 10
3.1 Zoning / Landuse / Facilities
This criterion determines an asset’s proximity to critical facilities. Detailed scoring and corresponding
facility types can be found in the CoF Weighting and Criteria flow chart in Section 3.9. The following
summarizes the GIS layers provided by the City that were intersected with asset layers to determine the
scoring for this criterion:
FacilitySitePoint – Point layer that contains critical facilities such as schools, special housing
units, health offices and public facilities within the City boundary.
FireStation – Point layer that contains fire stations located within the City boundary.
Park – Point layer that contains areas identified as parks located within the City boundary.
GeneralPlanLanduse – Parcel layer with assigned land use located within the City boundary.
Zoning District – Parcel layer with assigned zoning type located within the City boundary.
Table 3-3 and Figure 3-1 demonstrate Zoning / Landuse / Facilities CoF summary for Gravity Mains
only. Summary of other storm drain assets can be found in Appendix C.
Table 3-3: Zoning / Landuse / Facility CoF Summary for Gravity Mains
Zoning / Landuse
/ Facility CoF Count % of System
1 97 6%
2 30 2%
3 738 49%
4 319 21%
5 325 22%
Total 1,509 100%
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Figure 3-1: Zoning / Landuse / Facility CoF Summary for Gravity Mains
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3.2 Traffic Impact
This criterion determines and asset’s proximity to various road types within the City’s boundary. Detailed
scoring and corresponding road types can be found in the CoF Weighting and Criteria flow chart in
Section 3.9. The following summarizes the GIS layers provided by the City that were intersected with
asset layers to determine the scoring for this criterion:
RoadCenterline – Polyline layer with all roads within the City’s boundary, except for Railroads.
Assets located near the railroad were manually identified.
Table 3-4 and Figure 3-2 demonstrate Traffic Impact CoF summary for Gravity Mains only. Summary of
other storm drain assets can be found in Appendix D.
Table 3-4: Traffic Impact CoF Summary for Gravity Mains
Traffic Impact CoF Count % of System
1 81 5%
2 816 54%
3 54 4%
4 356 24%
5 202 13%
Total 1,509 100%
Storm Drain Asset Business Risk Exposure Recalibration Page 13
Figure 3-2: Traffic Impact CoF Summary for Gravity Mains
Storm Drain Asset Business Risk Exposure Recalibration Page 14
3.3 Environmentally Sensitive Areas
This criterion determines an asset’s proximity to environmentally sensitive areas identified by the City.
Detailed scoring can be found in the CoF Weighting and Criteria flow chart in Section 3.9 The following
summarizes the GIS layers provided by the City that were intersected with asset layers to determine the
scoring for this criterion:
EnvironmentallySensitiveArea – Polygon layer that contains environmentally sensitive
locations and buffer assigned by the City.
Table 3-5 and Figure 3-3 demonstrate Environmentally Sensitive Area CoF summary for Gravity Mains
only. Summary of other storm drain assets can be found in Appendix E.
Table 3-5: Environmentally Sensitive Area CoF Summary for Gravity Mains
ESA CoF Count % of System
1 1,262 84%
3 247 16%
Total 1,509
Storm Drain Asset Business Risk Exposure Recalibration Page 15
Figure 3-3: Environmentally Sensitive Area CoF Summary for Gravity Mains
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3.4 Special Flood Hazard Area CoF
This criterion determines an asset’s proximity to special flood zone areas identified by the City. Detailed
scoring can be found in the CoF Weighting and Criteria flow chart in Section 3.9. The following
summarizes the GIS layers provided by the City that were intersected with asset layers to determine the
scoring for this criterion:
FEMAFloodZoneCarlsbad – Polygon layer that contains areas identified by FEMA as flood
hazard areas.
Table 3-6 and Figure 3-4 demonstrate Special Flood Hazard Area CoF summary for Gravity Mains only.
Summary of other storm drain assets can be found in Appendix F.
Table 3-6: Special Flood Zone Hazard Area CoF Summary for Gravity Mains
Special Flood Zone Hazard
Area CoF Count % of System
1 1,463 97%
3 46 3%
Total 1,509 100%
Storm Drain Asset Business Risk Exposure Recalibration Page 17
Figure 3-4: Special Flood Hazard Area CoF Summary for Gravity Mains
Storm Drain Asset Business Risk Exposure Recalibration Page 18
3.5 Unit Type CoF
This criterion assigns a CoF score based on the type of the asset. Detailed scoring can be found in the CoF
Weighting and Criteria flow chart in Section 3.9. Table 3-7 demonstrates Unit Type CoF summary for
Gravity Mains only. Summary of other storm drain assets can be found in Appendix G.
Table 3-7: Unit Type CoF Summary for Gravity Mains
Unit Type CoF Count % of System
5 1,509 100%
Total 1,509 100%
3.6 Unit Sub-Type / Size CoF
This criterion assigns a CoF score based on unit subtype or size. Assets that have unit subtype
information were scored with a unit-subtype criteria. Assets that did not have unit subtype information
were scored based on size. Detailed scoring can be found in the CoF Weighting and Criteria flow chart in
Section 3.9.
3.6.1 Unit Subtype / Size CoF Override
In order to capture storm drain assets that are highly critical to the City, the Unit Sub-Type / Size CoF for
the following assets were replaced with a CoF of 5:
Major outfalls (list provided by the City)
Assets tributary to persistently flowing outfalls (list provided by the City)
Table 3-8 and Figure 3-5 demonstrate Unit Subtype / Size CoF summary for Gravity Mains. Summary of
other storm drain assets can be found in Appendix H.
Table 3-8: Unit Subtype / Size CoF Summary for Gravity Mains
Subtype_Size CoF Count % of System
1 178 11%
2 692 46%
3 314 21%
4 271 18%
5 54 4%
Total 1,509
Storm Drain Asset Business Risk Exposure Recalibration Page 19
Figure 3-5: Unit Subtype / Size CoF Summary for Gravity Mains
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3.7 Total CoF
CoF scores for each criterion and weighting shown in Table 3-1 and Table 3-2 were multiplied together
and summed to calculate a Total CoF score.
3.7.1 Total CoF Override
In order to capture storm drain assets that are extra critical to the City, the Total CoF score for assets with
the following criteria were replaced with a score of 5:
Zoning / Landuse / Facility CoF score of 5
OR
Traffic Impact CoF score of 5
3.8 Final CoF Results
Figure 3-6 and Figure 3-7 summarize Total CoF results for all storm drain assets after the application of
override.
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Figure 3-6: Total CoF Summary for All Storm Drain Assets
Storm Drain Asset Business Risk Exposure Recalibration Page 22
Figure 3-7: Total CoF Summary for Gravity Mains
Storm Drain Asset Business Risk Exposure Recalibration Page 23
3.9 CoF Flowchart
The following chart visually summarizes the CoF criteria, weighting and overrides applied to calculate
Total CoF of a storm drain asset. This flowchart is intended to assist the City in programming
consequence of failure logics in Innovyze InfoMaster software.
The flowchart begins with the CoF criteria at the very top, leading to the assigned weightings for each and
the final calculation of the Total CoF score. A legend is provided on the bottom left-hand corner to help
the user identify what criteria is applicable to what assets, the weighting assigned to a criterion, and when
to apply an override rule. This flowchart is applicable to all storm drain assets. An example of how to use
this flowchart for a gravity main is described below.
Scenario - Gravity Main with the following characteristics:
o Adjacent to a school
o Located under major arterial
o NOT located within ESA or Special Flood Hazard Area
o Conveyance size of 1.7 SF
o Tributary to persistently flowing outfall
Using the information above, the gravity main will be scored with the following using the text boxes
located below the CoF criteria blocks (in blue, green and yellow):
Zoning / Land Use / Facilities
o Since the gravity main is located next to a school, it will receive a score of 5 for this
criterion.
Traffic Impact
o Assets located next to a major arterial are assigned a score of 4.
Environmentally Sensitive Area
o The gravity main is NOT identified to be located within a ESA, assigning this asset a
score of 1.
Special Flood Hazard Area
o The gravity main is NOT identified to be located within a Special Flood Hazard Area,
assigning this asset a score of 1.
Storm Drain Asset Business Risk Exposure Recalibration Page 24
Unit Type
o Since this asset is a gravity main, it will be assigned a score of 5.
Unit Subtype / Size
o Referencing the legend in the bottom left-hand corner of the flowchart, gravity mains fall
under the yellow block, meaning that the size criteria will be used to score this asset.
o The gravity main has a conveyance size of 1.7 SF, corresponding to a score of 1.
This criterion leads to a blue override block in the flowchart. The gravity main is
identified to be tributary to a persistently flowing outfall, replacing the score of 1
with a score of 5.
Total CoF Score
o After all the scores have been assigned, multiply the scores by the corresponding
weighting. These are then summed to calculate the Total CoF Score.
This leads to a blue override block in the flowchart. Since the gravity main
received a score of 5 for the Zoning / Land Use / Facilities criteria, the Total CoF
Score calculated is replaced with a score of 5.
Zoning / Land Use /
Facilities Traffic Impact Environmentally
Sensitive Areas
Special Flood Hazard
Area Unit Type SizeUnit Sub-Type
Commercial Areas
Public Facilities
Schools 5
High Density Residential Areas
Tourist Areas
Industrial Areas
Community Facilities
------------------------------------------------------------------
Local Shopping Centers
Offices
Village Areas 4
Parks
Professional Areas
Senior Apartments
------------------------------------------------------------------
Medium and Low Density Residential
Agricultural
Local Shopping Centers 3
Mobile Home Parks
Residential Waterways
------------------------------------------------------------------
Rural Residential 2
------------------------------------------------------------------
Open Space 1
------------------------------------------------------------------
Planned Community: Use Land Use layer
Transportation Corridor: Traffic Impact Score
Prime Arterial: 5
Freeway: 5
Freeway Ramp: 5
Railroad: 5
Major Arterial: 4
Secondary Arterial: 4
Industrial Street: 3
Collector Street: 3
Local Street: 2
Local Street Cul-de-sac: 2
Alley: 2
Private Local Street: 1
Private Driveway: 1
Dirt Road: 1
Within 200-ft ESA
Buffer?
Yes: 3
No: 1
Within Special Flood
Hazard Area (FEMA)?
Yes: 3
No: 1
Gravity Main: 5
Junctions: 3
Inlet Structure: 2
Discharge Structure: 2
Clean Out: 2
Open Drain: 1
Detention Basin: 1
Gravity Mains
Conveyance Size (SF)
Size > 21 : 5
Size > 7 : 4
Size > 1.9 : 3
Size > 1.7 : 2
Size ≤ 1.7 : 1
Discharge Structures
Conveyance Size (LF)
Outfall with Classification
(A1,C1,A2,C2) refer to Unit Sub-
Type scoring
Size > 21 : 5
Size > 15 : 4
Size > 10.5 : 3
Size > 5 : 2
Size ≤ 5 : 1
Blank: 2
Curb Outlet: 2
Inlet Structures
Conveyance Size (LF)
Size > 21 : 5
Size > 16 : 4
Size > 10.5 : 3
Size > 5 : 2
Size ≤ 5 : 1
Null or 0: 2
Detention Basin
Area (SF)
> 200,000: 5
> 100,000: 4
> 50,000: 3
> 10,000: 2
≤ 10,000: 1
Blank: 2
Open Drain
Channel: 5
Ditch: 4
Connectivity Flow: 3
Swale: 1
Cleanout
Type A: 2
Type B: 1
Water Treatment Unit: 1
Junction
Connectivity: 3
Channel: 3
End Cap: 3
Pipe Junction: 3
Outfall
A1: 5
C1: 4
A2: 2
C2: 1
Unit Type
20%
Special Flood Hazard
Area
5%Environmentally
Sensitive Area
10%
Size / Unit Sub-Type
15%
Traffic Impact
30%
Zoning / Land Use /
Facilities
20%
Multiply by
Multiply by
Multiply by
Multiply by
Multiply by
Major outfall?
OR
Tributary to
Persistently
Flowing Outfall?
5 YESMultiply by
Sum Equals Total
CoF Score
All Asset Types
Gravity Mains, Discharge
Structures, Inlet Structures,
Detention Basins
Open Drains, Junctions,
Cleanouts
CoF Weighting
CoF score
(1-5)
LEGEND
Size / Unit
Subtype
Score
Size / Unit
Subtype
Score
NO
Multiply By
Override
Facility / Landuse /
Zoning Score 5?
OR
Traffic Score 5?
Final CoF
Score of 5YES
NO
Storm Drain Asset Business Risk Exposure Recalibration Page 26
4. Business Risk Exposure (BRE) Results
BRE scores for the City’s storm drain assets were calculated by multiplying Total CoF scores with
Probability of Failure scores.
Figures 4-1 to 4-8 summarize BRE results for all storm drain assets located within the Pilot area of the
City of Carlsbad.
Storm Drain Asset Business Risk Exposure Recalibration Page 27
Figure 4-1: BRE Score Summary for All Storm Drain Assets
Storm Drain Asset Business Risk Exposure Recalibration Page 28
Figure 4-2: Map of BRE Scores for Gravity Mains
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Figure 4-3: Map of BRE Scores for Clean Outs
Storm Drain Asset Business Risk Exposure Recalibration Page 30
Figure 4-4: Map of BRE Scores for Detention Basins
Storm Drain Asset Business Risk Exposure Recalibration Page 31
Figure 4-5: Map of BRE Scores for Discharges
Storm Drain Asset Business Risk Exposure Recalibration Page 32
Figure 4-6: Map of BRE Scores for Inlets
Storm Drain Asset Business Risk Exposure Recalibration Page 33
Figure 4-7: Map of BRE Scores for Junctions
Storm Drain Asset Business Risk Exposure Recalibration Page 34
Figure 4-8: Map of BRE Scores for Open Drains
Storm Drain Asset Business Risk Exposure Recalibration Page 35
5. Summary and Recommendations
This technical memorandum summarized the steps taken to recalibrate the City’s storm drain business
risk exposure and included a flow chart visualizing the updated logics for the recalibrated risk model..
The City’s storm drain assets included:
Gravity Mains
Discharge Structures
Inlet Structures
Detention Basins
Open Drains
Junctions
Clean Outs
A pilot area was defined and the gaps in the asset data were identified and closed using the City’s
institutional knowledge. A PACP compliant methodology was developed to turn the City’s existing
CCTV data into condition scores to increase the confidence in calculating the probability of failure.
Hazen began with the City’s existing consequence of failure methodology and additional criteria and
logics were added in order increase the confidence in the results. In addition, the weightings for the
criteria were adjusted and overriding rules were applied to ensure that the risk model reflects the City’s
goals, objective and priorities.
The risk results in the pilot area indicate that the City has 17 pipe segments with the total length of about
2,200 feet with a BRE score of greater than 4 (out of 5), out of which 11 pipe segments (about 1,300 feet)
has been televised in 2017. It is recommended the City plan for condition assessment of the remaining 6
pipe segments (about 900 ft) with BRE score of greater than 4 that have not been televised yet.
It is recommended the City expand the risk model to the entire service area in order to develop a
prioritized plan for a city-wide condition assessment.
Storm Drain Asset Business Risk Exposure Recalibration A-1
Appendix A – NASSCO PACP Condition Grading
System
Storm Drain Asset Business Risk Exposure Recalibration A-2
Storm Drain Asset Business Risk Exposure Recalibration A-3
Storm Drain Asset Business Risk Exposure Recalibration A-4
Storm Drain Asset Business Risk Exposure Recalibration A-5
Storm Drain Asset Business Risk Exposure Recalibration A-6
Storm Drain Asset Business Risk Exposure Recalibration A-7
Appendix B – Useful Lives Used for PoF Calculation
Storm Drain Asset Business Risk Exposure Recalibration A-8
Appendix C – Zoning / Landuse / Facility CoF Results
The following pie charts represent asset CoF summaries for this criterion. In the data callouts, please refer
to the following to identify count, percentage, and the legend for these graphs.
Storm Drain Asset Business Risk Exposure Recalibration A-9
Storm Drain Asset Business Risk Exposure Recalibration A-10
Appendix D – Traffic Impact CoF Results
The following pie charts represent asset CoF summaries for this criterion. In the data callouts, please refer
to the following to identify count, percentage, and the legend for these graphs.
Storm Drain Asset Business Risk Exposure Recalibration A-11
Storm Drain Asset Business Risk Exposure Recalibration A-12
Appendix E – Environmentally Sensitive Area CoF
Summary
The following pie charts represent asset CoF summaries for this criterion. In the data callouts, please refer
to the following to identify count, percentage, and the legend for these graphs.
Storm Drain Asset Business Risk Exposure Recalibration A-13
Storm Drain Asset Business Risk Exposure Recalibration A-14
Appendix F – Special Flood Hazard Area CoF
Summary
The following pie charts represent asset CoF summaries for this criterion. In the data callouts, please refer
to the following to identify count, percentage, and the legend for these graphs.
Storm Drain Asset Business Risk Exposure Recalibration A-15
Storm Drain Asset Business Risk Exposure Recalibration A-16
Appendix G – Unit Type CoF Summary
The following table summarizes the Unit Type CoF summary for each asset type. Visuals were not
included as this criterion is assigned based on the unit type solely.
Storm Drain Asset Business Risk Exposure Recalibration A-17
Appendix H – Unit Subtype / Size CoF Summary
The following pie charts represent asset CoF summaries for this criterion. In the data callouts, please refer
to the following to identify count, percentage, and the legend for these graphs.
Storm Drain Asset Business Risk Exposure Recalibration A-18
A-19