Final Newea 9 09 10 Mh Rehab
30
Inspection to Rehabilitation: A Risk Based Approach to Managing Manhole Rehabilitation Dollars Hillsborough County, FL Water Resources Services
description
PPT presentation to illustrate the power of our deliverables for condition assessment, prioritization, O&M, CIP and risk assessment.
Transcript of Final Newea 9 09 10 Mh Rehab
Inspection to Rehabilitation: A Risk Based Approach to Managing Manhole Rehabilitation Dollars
Hillsborough County, FL Water Resources Services
Presentation Overview
• Project Background• Manhole Structural Condition Assessment• Manhole Repair Recommendation Approach• Repair Prioritization Using Risk Based
Evaluation• Review Benefits of Approach
Why Did the Approach Make Sense?
• Risk of failure was determined for every manholes• Maximizes the benefits versus costs• Simplifies evaluation of condition, risk and the extent
of rehabilitation • Provides ability to compare cost of discrete versus
comprehensive repairs for each manhole• Provides a basis for estimating bid item quantities
and construction costs
Additional Benefit
• Provides a better understanding of the financial requirements for manhole rehabilitation
• Demonstrated the financial benefits of discrete rehabilitation
• Elevated awareness of the impact of infiltration and corrosion on manhole deterioration
• Provides a repeatable process for the future
Project Background
Total Population –
Total Population – 1,150,000
• Three Cities: Tampa, Plant City, and Temple Terrace
• Unincorporated Population – 750,000
Projected Growth for Next 20 Years: 3-5 %
Hillsborough County, FL
Project Objectives
Conduct County-wide Comprehensive Program
Integrate All Data Into CAMS/GIS Databases
Establish Asset Condition and Address O&M Immediate Needs
Project Time Line and Scope
•29,275
Number of Manholes
•6,256,128 ft.
Linear Feet of Pipe
•6” to 42”
Pipe Diameter Size Range
•15.9% (996,000 ft)
Pipes Cleaned
•1.5% (93,000 ft)
Pipelines Inspected w/CCTV
•5.4% (1,526)
MHs Requiring Repair
• Completed in two years• Hillsborough became
proactive• Addressed its
immediate needs
Manhole Structural Condition Assessment
• Zoom inspection enabled consistent recording of observations for documenting manhole defects
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Manhole Structural Condition Assessment
• PACP certified personnel reviewed video recordings, identified defects and graded the condition of each manhole
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Manhole Structural Condition Assessment
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Excellent•Acceptable Condition
•Minor Defects only
Good •Minimal collapse likelihood in short-term, but
potential for future deterioration
•Defects that have not begun to deteriorate
Fair •Collapse unlikely in near future but further
deterioration likely
•Moderate defects that continue to deteriorate
Poor •Collapse likely in foreseeable future
•Severe defects that can become a 5 in the near future
Immediate Attention•Collapse or collapse imminent
•Defects requiring immediate attention
1 2 3 4 5
Manhole Rehabilitation Recommendations
• 1,526 manholes with a structural grade of 5 or 4 were evaluated
• Defects were identified in each manhole component• The extent of rehabilitation was determined• Provided for each Service Area:
– Rehabilitation recommendations,– Bid item quantities, and– Estimate of the most probable construction cost.
Manhole Rehabilitation Recommendations
• Two methods of repair were considered– Discrete repair of
localized manhole components
– Comprehensive, frame to invert repair and epoxy coating
Manhole Rehabilitation Recommendations
• Factors Considered– Location of defect in
manhole– Extent of defects in
manhole– Depth of manhole – Infiltration– Corrosion
Manhole Rehabilitation Recommendations
• MS Access application developed to review defects and to evaluate the extent of repair required
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Manhole Rehabilitation Recommendations
Bid item quantities were summarized for each manhole
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Manhole Rehabilitation Recommendations
• 1,373 Manholes (90%) - Comprehensive, frame to invert repair and epoxy coating recommended
• 153 Manholes (10%) - Discrete repair of localized manhole components recommended
• $381,000 cost savings realized
ComprehensiveDiscrete
Initial Deliverable
• Maps indicating the location of manholes recommended for repair
• Repair recommendations, costs and bid item quantities for each of the 1,526 manholes
• Summary of repair costs and quantities for manholes located within 3 service areas
• Bid tabulations and cost estimates developed for each of the 3 service areas
Initial Deliverable
• Total estimated repair costs:– Area 1 $2,187,000– Area 2 $1,115,000– Area 3 $1,320,000
• Total Cost: $4,622,000• Prioritization – Address
grade 5 manholes then grade 4 manholes
Area 1 Area 2 Area 3$0
$500,000
$1,000,000
$1,500,000
$2,000,000
$2,500,000
Initial Deliverable• Issues
– Total rehabilitation cost was more than budget
– Service Area approach didn’t maximize cost/benefit
– Risk based approach must be developed
• Recommendations must consider risk across entire service area
• Must have ability to adjust scope in future years based on available funds
Risk Consequenceof Failure
Probability of Failure
Objective:• Consider the consequence of failure• Consider the probability of failure
Refined Prioritization ApproachRisk-based Prioritization Approach
Consequence of Failure
• Information gathered from Client records, zoning, GIS• Considered the consequences of a manhole failure on
the following:– Environment– Health and Safety– Public Service– Cost of Operation– Cost of Repair– Regulatory
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Probability of Failure
• Derived from condition of manhole• Considered the following failure mechanisms:
– I/I– Structural– Corrosion– Safety
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Risk Evaluation MatrixMACP Condition Score 2 1 3 2 1 1
Failure Mode Risk FactorsHigh Score
Failure Modes I/I Capacity Structural O&M Corrosion Safety
Failure ProbabilityWeight
Consequences of Failure
Scores15% 5% 35% 15% 5% 5%
Environment 3 0.45 0.15 1.05 0.45 0.15 0.15 1.05Health and Safety 1.75 0.26 0.09 0.61 0.26 0.09 0.09 0.61Public Service 0.75 0.11 0.04 0.26 0.11 0.04 0.04 0.26Cost of Operation 1 0.15 0.05 0.35 0.15 0.05 0.05 0.35Cost of Repair 0.5 0.08 0.03 0.18 0.08 0.03 0.03 0.18Regulatory 0.5 0.08 0.03 0.18 0.08 0.03 0.03 0.18
Failure Modes I/I Capacity Structural O&M Corrosion Safety
Risk Factor 0.45 0.15 1.05 0.45 0.15 0.15
Structural Utility Condition Index 65
O&M Utility Condition Index 85
Consequence of Failure
Scores
MACP Condition
ScoresProbability of Failure Scores
RiskScores
Verification of Risk Evaluation
• Field Verification – Revisited 300 Manholes– Indicated as high risk– Exhibited I/I sources– Exhibited evidence of corrosion
• Findings– Further deterioration in 15 percent of manholes– Infiltration and corrosion accelerated deterioration– All 300 manholes were found to be in need of near term
repair
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Effects of Manhole Surface pH on Years of Remaining Life
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Source L.A.County San District
0.001 0.01 0.1 1.0Corrosion Rate (in./year)
7
6
5
1
0
pH
Cor
rosi
on
Ran
ge
4
3
2
0.25
For pH of 2Expect about
.25 in/yearwall loss
Final Deliverable
• Risk based prioritization process • Each manhole was assigned a risk score• Manholes sorted from greatest to least risk score• Cumulative repair costs were determined• Manholes were selected for rehabilitation from the
cumulative repair cost list based on available funds• A bid tab, estimated quantities and estimate of most
probable construction cost
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Benefits of Approach
• Minimize impacts by addressing manholes based on risk (CoF x PoF)
• Maximized benefits within limited budget constraints• Address additional manholes by considering discrete
manhole repairs• Provided confidence that limited funds were put to best
use• Provided a repeatable asset management process that
will be used in the future
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Current Status of Project
• County appropriated funds and secured a contractor to rehabilitate the first 500 prioritized manholes
• Repair work will begin within the next few weeks.• This approach is being applied to capital planning of
pipeline improvements
13.9%
41.7%
3.9%
CI
DI
Steel
PVC
PE
AC
GRP
RCP
PCCP
Other
Q&A / Point(s) of Contact
William DiTullioPresidentInfraMetrix, LLC9208 Florida Palm DriveTampa, FL 33601(813) [email protected]
Bob KerryProject ManagerInfraMetrix, LLC1785 Hooksett Road.Hooksett, NH 031061(603) [email protected]
www.inframetrix.comhttp://inframetrix.wordpress.com
http://twitter.com/inframetrix
QUESTIONS
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