Download - Asset Management with GIS
A$$et Management With GISA Stormwater Utility Perspective
What does a Stormwater Utility do?
• Road drainage
Maintenance, repair & construction of stormwater pipes
• Dams Prevent downstream flooding
• Water QualityRegulatory compliance & reducing pollution
Then (pre-2006)
• Reactive utility
• Funding source – general tax fund
Historical Service Requests
Water
Federal EPA(Agency)
NPDES permit (1990)Large cities > 100K
Nonpoint Source PollutionImprove Watershed
Reduce Pollutant Loadings - TSS(Fecal Coliform, Biota – Fish & Macroinvertebrates)
Federal Clean Water Act of 1987 And Amendments
State EPD (Division of DNR)
County and Municipal Stormwater Plans
Now (2006 & Forward)
• Proactive Utility
• Technology
Decisions, Decisions
• Identify most vulnerable assets
Through critical analysis.Criteria were identified through brainstorming. What data supports the analysis?
Why waste time and resources inspecting good features?
Who gets involved?• WIP• DAMS• Construction plans• Maintenance
•Compliance (with WQ)•Inspections (SRs)•GIS
How Do We Decide? Then: “Respond to Service Requests” & “Do pond inspections”
Now: NPDES 5 year permit from EPD “Inspect 10% of the total assets” “Inspect 20% of the most critical over 5 years & repair if needed”
Maximum Cost Benefit
What is the most critical?
• Risk Assessment ModelLikelihood of Failure Consequence of Failure
Likelihoodof failure y-axis
Criteria Weight
Corrosive Soils 20
Age, % of useful remaining life 80
Pipe material 100
Inspection results 100Inspection results: Inventory based on Good/Fair/Poor Objective Visual Assessment Inventory done over several years beginning in 2000
Criteria Scoring ( 0 = low consequence, 10 = high consequence)* factor of ten
Consequenceof failure x-axis
Criteria WeightDiameter 90
Potential for Safety Risk and/or Property LossProximity to buildingsProximity to Critical Facilities (hospitals, fire stations, etc.)Proximity to roads and bridges
808080
Proximity to Impaired (303(d)) Streams 40
Proximity to Environmentally Sensitive Areas Watershed improvement projectsDrinking water sources
3030
Criteria Scoring ( 0 = low consequence, 10 = high consequence)* factor of ten
Y-axisInitial Development-Likelihood
X-axisInitial Development - Consequence
Y-axisFinal Likelihood Weights
X-axisFinal Consequence Weights
Data Clean-up & Building of Ranges
Soil type
All Gwinnett County soil is acidic
Codes of pipes
Data Dictionary or Metadata for Codes
Pipe life expectancy
Pipe Life Expectancy
Assuming You Have Stormwater Inventory Data…
2000 2002 2004 2006 2008 2010
Whole subdivisions
Last Contract Deliveries
GPS in-house
Digitized from plats/fieldwork
PondsContracted Out Inventory/Assessment
Assuming You Have Stormwater Inventory Data…
Select county maintained pipes
Start with Existing STW Attribute Table
Build “Likelihood”
Quantifiable data…
Create new fields
Then
Now
Diff
Material_l
field calculate them
Create New fields and Field Calculate
Create new fields
Remainlife
Perc_RUL
field calculate them
Create New Fields and Field Calculate
Create new fieldRUL_score
Select records
Perc_RUL <= 20
Field calculate RUL_score
10 * 80 (weight*factor) = 800
Complete the remaining records
by selected ranges
Finish Loading the RUL_score Data Fields With Final Scores Based on Weight
Create new fieldMaterial_S
Select records “PL” or “CO”
Field calculate Material_s10 * 100 (weight factor) = 1000
Complete the remaining records by selected ranges
Finish Loading the Material_s Data Fields with Final Scores Based on Weight
Build ConsequencesAll consequences are related to proximityExcept for Pipe Diameter
Use the “Join data from another layer based on spatial location”. “Minimum”.
Final Matrix
Graph the results in the *.mxd …
You can select the most critical likelihood and consequence scores in the graph and see them in the view
Graph the resulting matrix in the *.mxd Tools>Graphs>Create>Scatterplot
Unranked pipes pre-SAMP
Ranked Pipes with SAMP
Most Critical Pipes with Flood Sites
*.avi
800 of the most critical pipes
Results (static image)
Annual Pipe Inspections
Total pipe assets
20%
20%
20%
20%
20% annual inspection
Total pipe assets
10%
10%
10%
10%
10%
10%
10%
10%
10%
10%Critical pipes thoroughly pole camera or video inspected annually – PACPS.
Within 5 years, all the most critical will have been inspected.
Pre-Suggested by EPD Approved with SAMP
The critical pipes happened to be 5% of the total pipe mile assets.
EPD Approved!
This is the first known SAMP for SEPARATE (MS4) stormwater system in the USA
Critical Pipes With Contiguous Inspection
Critical Pipes with
Contiguous Inspection
Priority 1 Flood Sites
Priority 2 Flood Sites
Priority 3 Flood Sites
The Cycle of Review
What did inspections reveal?
Should we revise criteria for rating pipes?
Is the SAMP working?
Do we re-run the matrix with refreshed scores?
Are there other consequences
to consider?
Contactswww.gwinnettstormwater.com
678-376-7193
• Steve Hart, Planning [email protected]
• Karen Lougee, GIS [email protected]
• John Dean, GIS [email protected]