Brisbane Water’s

Sewer Trunk Trunk Main RehabilitationProgram

“A Practical Overview”

Overview of Presentation� Trunk Sewer System Overview;� Maintenance Planning - Condition Monitoring :

– Fail Modes;– Risk Assessment ( Generation 1);– Condition Monitoring Technology;– Inspection Intervals of trunk sewers;– Risk Assessment (Generation 2);

� Strategic Asset Management - Renewals Planning &Investment :– What is Renewal Planning & Investment?;– Renewal Plan Information Needs;– Renewal Priortisation Tool;– Renewal Options/ Costing Model;

� FUTURE WORK

BCC Trunk Sewer System Overview

� transport & treat over 300 ML day of wastewater� recycle/reuse 15 ML day� 411,000 properties served� 220 km rising mains sewers (all dia)� 430 km trunk sewers (> 300 dia)� 6150 km retic sewers (100 to 300 dia)� 10 treatment plants� 2 recycled water plants� 204 pump stations� 6th largest network� CRC $3.1 Billion� WDRC $1.64 Billion

Maintenance Planning - ConditionMonitoring

Michael’s Presentation

Strategic Asset Management -Renewals Planning & Investment

What is Renewals Planning &Investment?

� International Infrastructure Management (IIMM)definition:

“Renewal expenditure is major work which does notincrease the asset’s design capacity but restores,

rehabilitates, replaces or renews an existing asset toits original capacity. Work over and above restoring an

asset to original is new works expenditure(Enhancement).”

Renewal Plan Information Needs

� GIS Sources:– Asset Data:

• nominal diameter;• length & depth;• pipe material;• bedding type e.g Is the pipe concrete encase?;• year constructed;• pipe class to determine original wall thickness/ internal diameter;• location of pipe segment e.g Is the pipe segment in a roadway,

backyard, park etc….;• location of DS manhole;• soil type;• geographical location & surrounding environment.

.

Renewal Plan Information Needs Cont.

� Condition Monitoring Sources:– CCTV scores & videos:

• Structure Score (Sewer Rat/ WSAA Sewer Inspection Code)• Service Score (Sewer Rat/ WSAA Sewer Inspection Code)• In the form of a WINCAM report (refer to example)

– Field Inspections:• Carbonation/ oxidation depth (Phenol Test);• ledge distance;• wall loss;• pH measure;• aggregate diameter;• measured internal pipe diameter.

.

Renewal Plan Information Needs Cont.

� Corporate Knowledge:– People knowledge….

“40 years in the business” ….they were the engineers/ field staff who constructed/maintain these assets….

a rare breed…..

– The old design manuals e.g 1973 Hardie’s Pipeline Manual;– As - Constructed Drawings;– Field Books;– Maintenance History.

.

Renewal Plan Priortisation Tool� Renewal Plan Priortisation tool is based on:

Risk Ranking = Likelihood x Consequence

� Consequence criteria (weighted):– Lines Downstream of Eros Structure– Environmentally Sensitive Areas;– Assets greater than 375 mm in Diameter;– Isolated Asset;– Within 25 metres of a water course;– Sewers within the CBD;– 20 metres of a Roadway.

� Likelihood criteria (weighted):– CCTV Inspection Report;– Percentage of Wall Loss;– pH Level (Bacteria still present);– Bedding Type (Line Segments thought to be Concrete Encased);– Pipe Material;– Soil Type.

� References– IIMM;– WRc Sewerage Rehabilitation Manual 4th Vol 1 & 2;– AS4360 - Risk Management.

Renewal Plan Priortisation Tool Cont.� Consequence score (1-5) is based on:

5 - Catastrophic4 - Major3 - Moderate2 - Minor1 - Insignificant

� Likelihood score (1-5) is based on:5 - Almost Certain - Collapse or collapse imminent (within 12 months);4 - Likely - Collapse likely in foreseeable future (within 2-3 years)3 - Moderate - Collapse unlikely in the near but further deterioration likely (within 5years)2 - Unlikely - Minimal Collapse likelihood in short term but potential for furtherdeterioration (reinspect 5 years after the last CCTV)1 - Rare - Acceptable structural condition e.g reinspect 10 years after the lastCCTV.

� Risk Ranking generated:

Insignificant Minor Moderate Major CatastrophicAlmost Certa A Low (004) Med (016) High (032) Very High (064) Extreme (128)Likely L Low (002) Med (008) Med (016) High (032) Very High (064)Moderate M Neg (001) Low (004) Med (008) Med (016) High (032)Unlikely U Neg (0.5) Low (002) Low (004) Med (008) Medium (032)Rare R Neg (000) Neg (0.5) Neg (001) Low (002) Low (016)

Likelihood Consequence

Renewal Options/ Costing Model� Renewals Options:

– Place on the reinspection program (delay renewals);– Capacity Increase based on Master Planning (part enhancement/ part renewals);– Replace like with like (renewals);or– Rehabilitation/ Reline (renewals);– Conduct an NPV analysis where required.

� Costing Models:– Costing data sources:

• Rehabilitation/ Relining costs sourced from external relining contractors & BWprojects;

• Replace like with like costs sourced from Asset Valuation process and BWProjects;

– Costing Model includes• Preliminaries such as Site Set-up;• Material and Construction Costs;• Flow Control and Traffic Costs;• Project and Construction Management Cost;• Overheads and BW Margins.

FUTURE WORKS� R&D - Development of a Failure Prediction Model based on

– remaining pipe thickness;– understanding the influence of concrete encasement on pipe strength;– inspection interval;– material types;– Factor of Safety reduction.

� R&D - Laser Profiling;� R&D - Trial new camera technology/ Panorama views etc;� R&D - Sonar technology to measure grit in sewer;� R&D - Renewal Investment Planning - What is the appropriate level

of investment?