Base Engineering Assessment Program

Reticulated Services Assessment Manuals

Stormwater Systems

Glossary

Acronym/Abbreviation / Description
General
AC / Assessment Consultant
AS / Australian Standards
BEAP / Base Engineering Assessment Program
BSOO / Base Support Operations Officer
CIOG / Chief Information Officer Group
CMC / Comprehensive Maintenance Contractor
CMS / Comprehensive Maintenance Service
Defence / Department of Defence
DEMS / Defence Estate Management System
DSRG / Defence Support and Reform Group
DSM / Defence Security Manual
ERAT / Estate Risk Assessment Tool
ICT / Information and Communication Technology
ISM / Australian GovernmentInformation Security Manual, August 2011
MFPE / Defence Manual of Fire Protection Engineering
MIEE / DefenceManual of Infrastructure Engineering - Electrical
WHS / Workplace Health and Safety (also Occupational Health & Safety)
O&M / Operations and Maintenance
REO / Regional Environmental Officer
RIM / Regional Information Manager
SDMP / Spatial Data Management Plan
WoL / Whole of Life
Water, Sewerage and Stormwater
ADWG / Australian Drinking Water Guidelines
AGWR / Australian Guidelines for Water Recycling
AHD / Australian Height Datum
ARI / Average Recurrence Interval
AR&R / Australian Rainfall and Runoff
CCTV / Closed Circuit Television
CICL / Cast iron concrete-lined
DICL / Ductile iron concrete-lined
DTM / Digital Terrain Model
EPA / Environment Protection Agency
FPM / Facilities Planning Manager
FU / Fixture unit
GPT / Gross Pollutant Trap
HPC / Heterotrophic Plate Count
LiDAR / Light Detection and Ranging
L/s / Litres per second
P&ID / Process and InstrumentationDiagrams
PE / Polyethylene
PVC / Polyvinyl Chloride
SPS / Sewage Pump Station
STP / Sewage Treatment Plant
UUM / Urgent and Unforseen Maintenance plumbing contractor
XP SWMM / Stormwater & Wastewater Management Model
WSAA / Water Services Association Australia
Spatial System
CAD / Computer Aided Design (often referring to Auto CAD™)
GIS / Geographic Information System

Table of Contents

Glossary

1Stormwater Systems

1.1Overview

1.3Data Collection

2Stormwater Network Assessment

2.1Description

2.2Data Collection

2.3Capacity Assessment

2.4Condition Assessment

2.5Compliance Assessment

3Flood Immunity

3.1Description

3.2Data Collection

3.3Capacity Assessment

3.4Condition Assessment

3.5Compliance Assessment

4Water Quality

4.1Description

4.2Data Collection

4.3Capacity Assessment

4.4Condition Assessment

4.5Compliance Assessment

Tables

Table 1-1Engineering Service assessment parameters

Table 2-1Defence Clauses for Function Design Briefs

Table 2-2Structural condition for pits, headwalls, tidal flaps and GPTs

Table 2-3Serviceability condition for pits, headwalls, tidal flaps and GPTs

Table 2-4Structural condition for open channels

Table 2-5Serviceability condition for open channels

Table 3-1Serviceability condition for flow paths

Table 3-2Defence Clauses for Function Design Briefs

Table 3-3Melbourne water hazard classes and criteria

Table 4-1Structural condition - water quality improvement devices

Table 4-2Serviceability condition – water quality improvement devices

Appendices

Appendix A Stormwater Data Required cChecklists

Appendix BStormwater Master Spreadsheet – Refer Electronic File

Appendix CSTANDARD ASSET LIFE – STORMWATER ASSETS

Appendix DStormwater Data Collection Forms – Refer Separate Electronic Files

Appendix EStormwater system QUESTIONNAIRE

December 20131

Base Engineering Assessment Program

Reticulated Services Assessment Manuals

Stormwater Systems

1Stormwater Systems

1.1Overview

This report outlines the general criteria and guidelines for undertaking a capacity, condition and compliance of a stormwater system, in respect to the Base Engineering Assessment Program (BEAP).
The Department of Defence instigated the Base Engineering Assessments Program (BEAP) to establish the risk and cost exposure related to reticulated services at various Defence sites. This information will, in the future, be used by the sites to inform the Base Development Planning process. The results and recommendations from the BEAP will also contribute to an improved understanding of the maintenance and reinvestment liability for each of the specified sites.

1.1.1Summary of the assessment process

The assessment processis based on a combination of existing information made available to the assessment team, site inspections, and investigations to obtain any missing data necessary to complete the analysis. The assessments are undertaken in a three-phase process:

Phase One—Investigation and analysis.This phase provides a preliminary assessment and information gap analysis and culminates in a report to the Base Engineering Assessments Program along with a detailed proposal for undertaking Phase Two investigations.
Phase Two—Physical Investigations. This phase provides the detailed physical site investigations and services modelling that is agreed to be required to investigate the gaps in information identified in Phase One. This Phase includes detailed summaries of the assessment process and outcomes (presented as investigation Completion Reports–ICRs).
PhaseThree—Final Reporting.This phase provides the consolidated assessment of the findings of Phases One and Two in a comprehensive report to the Base Engineering Assessment Program.

The BEAP assessment methodology applies the DSRG Estate Risk Assessment Guidelines. Specifically, the seven categories of risk defined in the Estate Risk Assessment Tool (ERAT) are used, which are capability, workplace health and safety (WHS), environment and heritage, legal compliance, financial efficiency, personnel and reputation. Each engineering service is assessed against the ERAT risk categories to determine the likelihood and consequence of risk events.
A priority is assigned to each recommended remedial action for the specific Defence precinct. The BEAP assessment methodology uses the prioritised work request (WR) categorisation system described in the DSRG Infrastructure Appraisal Policy.
The assessment criteria used to assess each utility engineering service status for capacity, condition and compliance is provided in Table 1-1.

Table 1-1Engineering Service assessment parameters

Assessment parameters used to establish the service status
Capacity / Condition / Compliance
Exceeded
100% of service capacity has been used.
Manhole/pit capacity exceeded and overland flooding experienced at depth greater than 100 mm. / Unserviceable
Not capable of functioning as intended, obsolete equipment / components, unable to be maintained – requiring full replacement / upgrade. / Non-Compliant
Design does not comply with applicable design guidelines, Australian Standards and Defence Policy requirements.
Poor
Deterioration is severe and is limiting the serviceability of the asset. Maintenance cost would be high.
Marginal
75%>x<100% of service capacity has been used. Likely to be non-compliant with design requirements for spare capacity.
Manhole capacity not exceeded under relevant ARI but exceeded under the next higher ARI assessed. For the 100-year ARI, an average water level over ground level ratio was adopted from all previous ARIs assessed and applied. / Fair
Deterioration is obvious and there is some serviceability loss.
Within Limits
<75% of service capacity has been used.
All manholes not falling within the above categories. / Good
Signs of deterioration evident, serviceability would be impaired very slightly. / Compliant
Design complies with applicable design guidelines, Australian Standards and/or Defence Policyrequirements.
As New
No visible sign of deterioration, recently constructed / installed, or recently rehabilitated back to new condition.

1.2Overall Assessment Outcomes

1.2.1Stormwater assessment standards and guidelines

The standards, guidelines and legislative requirements relevant to a stormwater assessment include:

Engineering Development Standards prepared by the local government in which the base is located
Water Sensitive Urban Design (WSUD) Principles
Australian Rainfall and Runoff 1987 (Format and Presentation update only for 2000)
AS3500.3 Stormwater Drainage
Standard Clauses on Civil Engineering for Inclusion in Functional Design Briefs, Department of Defence (
Environment Protection and Biodiversity Conservation(EPBC) Act
ANZECC: Australia and New Zealand Environment and Conservation Council, Australian and New Zealand Guidelines for Fresh and Marine Water Quality, October 2000
Defence Environmental Performance Reporting.

1.3Data Collection

1.3.1Data checklists / Data required tables

A complete data checklist for the stormwater system assessment (including all sub service components) is included in Appendix A, and outlines the scope and type of data that should be collected to undertake the assessments. The intent of the checklist is to prompt the data collection phase of the project and should be completed over both Phase One (initial data collection) and Phase Two (physical investigations and analysis). Some data generated in the Phase Two of the process to complete the checklists will include information collected during site inspection (such as CCTV) and information generated by the analysis (such as hydraulic models and master spreadsheets).

1.3.2Master spreadsheets

Part of the assessment process involves generating a Stormwater Master Spreadsheets. The master spreadsheet records the details of the capacity, condition and compliance assessments, along with details relating of each asset. The master spreadsheet will act as an asset register and will aid in Defence’s long-term management of the stormwater system. Any existing DEMS asset number should be recorded in the master spreadsheet. An initial asset register should first be developed for all system components with unique IDs for each asset. These asset registers will be developed into master spreadsheets during the assessment process. Separate ID should be included for:

Each kerb inlet pit
Each field inlet pit
Each maintenance hole
Each headwall and endwall
Each section of stormwater main (between pits or maintenance holes)
Each outwall/tidal flap
Each open lined drain
Each major unlined flood channel
Each stormwater system structure including detention basins, gross pollutant trap, ponds, tanks, weirs, discharge structures and outlet points.

A sample stormwater Master Spreadsheet tab is included in Appendix B (separate electronic file). A separate tab should be developed for each asset type (pipeline, pit, outlet, etc.).

1.3.3Risk and criticality

Risk should be considered at all stages during the assessment process. If any P1 (Priority 1) Workplace Health and Safety Hazards are noted at any stage of the assessment process, these should immediately reported to base staff and to DSRG (through weekly reporting) to ensure that the hazard is eliminated or mitigated as soon as practicable.
During Phase One, network criticality and risk should be considered when developing the scope of the inspections. All critical infrastructure (e.g. major stormwater assets such as channels, detention basins, outlets which are visible) should be inspected confirmed during Phase One, along with the critical network components (trunk stormwater mains).
During Phase Two, where physical investigations will not be undertaken for the entire system, priority should be given based on criticality and the risk of not being able to confirm data (i.e. preference may be given to CCTV inspections on a trunk stormwater main with no pipe size or material details rather than a network branch that may receive higher flow, but has known details.

2Stormwater Network Assessment

2.1Description

The stormwater network consists of open channels, stormwater mains and pits and various structures such as detention basins and outlet points. The stormwater mains, pits and channels included on the Site Services plan will include the trunk network system (generally 225mm diameter and greater). The network may also include some smaller diameter stormwater mains.
Some local drainage elements (such as downpipes and associated kerb outlets, or single pipe runs beneath roadways) are not assessed as part of the BEAP.
The Stormwater network assessment should be based on three generic guidelines/standards:

Engineering Development Standards prepared by the local government in which the base is located, or alternatively AS3500.3 Stormwater Drainage
Standard Clauses on Civil Engineering for Inclusion in Functional Design Briefs, Department of Defence (
Australian Rainfall and Runoff 1987 (Format and Presentation update only for 2000).

2.2Data Collection

The stormwater system data collection questionnaire (Appendix E) includes specific questions relating to the stormwater network. Data collection forms (Appendix D) also include prompts for specific data requirements that are needed to undertake the assessment.
Data required for the stormwater network assessments includes pipe and channel details (invert levels, internal diameter or dimensions, material type and age) and inlet details (inlet length and level, invert level, internal dimensions, material type).
Spatial data should first be confirmed during Phase One to establish network connectivity and to confirm the direction of flow throughout the reticulated network. Pipeline diameter should be confirmed from the Site Services plan or other existing information. If there is no information for any critical trunk sections of the network, then this data gap should be recorded so that pipe inspections can be undertaken during Phase Two.
Pipe and pit or maintenancehole invert levels may be included on the Site Services plan or on separate survey plans and should be reviewed for accuracy. Where additional level information is required to undertake an assessment of the trunk network, this requirement should be recorded so that level survey data can be collected in conjunction with any pipe condition surveys during Phase Two.
Pipe material and age information is not as critical for the assessments; however, all available data sources should be reviewed to determine if indicative construction periods can be used for different areas of the base based on the level of information available. If an estimate of material and age can be made, this is likely to be more cost effective that a full network-wide survey.
Phase Two physical inspections are likely to include:

A CCTV survey of a sample of the network pipelines. This survey will allow some data gaps to be filled in relation to pipe diameter and material and is also required for the condition assessment. The data will be recorded electronically (video files and summary reports)
Inspections of pits and maintenance holes. The information should be recorded on data collection forms (Appendix D)
Level surveys of pipe inverts and channels along critical trunk sections. The information will usually be recorded by the surveyor and included on a .dwg files, or can be recorded manually on inspection sheets.

2.3Capacity Assessment

2.3.1Stormwater pipes and pits

Pit and pipe stormwater networks are generally required to accommodate a 1 in 10 year ARI storm event in accordance with Defence guidelines (Standard Clauses on Civil Engineering for Inclusion in Functional Design Briefs). The local government typically requires design for a 1 in 10 Year ARI.

Defence Clauses for Function Design Briefs(Design Brief) provides a benchmark for the capacity and compliance of the stormwater system. An extract is included in. Table 2-1.

Table 2-2Defence Clauses for Function Design Briefs

Location / Criteria
Operational Buildings / Floor level 0.3m above the 100 year ARI flood level.
Other buildings / Floor level 0.2m above the 50 year ARI flood level.
Main access road / Depth of flooding during a 50 year storm should be less than 0.1m.
Other roads, car parks, etc. / Depth of flooding during 10 year ARI storm should not exceed 0.1m for roads and 0.03m for car parks.

The capacity of gravity stormwater mains and inlets is generally assessed by:

Discussions with base staff ascertain whether any capacity issues are evident (e.g. localised flooding events occurring at regular frequencies)
Undertaking hydraulic modelling of the stormwater trunk system using an appropriate software package and a 1 in 10 year ARI design storm event.

2.4Condition Assessment

2.4.1Stormwater Pipes

Stormwater pipes including culverts are graded on a scale of 1 to 5, with 1 representing ‘As new’ condition and 5 representing an ‘unserviceable’ condition (as per Table 1-1).
Stormwater mains are graded using two criteria:

Structural: The extent and significance of structural defects such as cracking, holes, collapse/partial collapse, and joint displacement. Typically, a stormwater pipe with a poor structural score requires renewal either through re-lining, pipe bursting or either replacement.
Serviceability: The extent and significance of defects that affect hydraulic performance such as tree root intrusion, debris, and silt/ solids deposition. In many instances, a main with a poor serviceability score can be addressed through maintenance (e.g. jetting or jetting and root foaming). Where blockages resulting from root intrusion continues to be frequent even with improved maintenance, or, if the extent of root intrusion causes structural defects, renewal of the stormwater pipe may need to be considered where cost-effective.

Using the Conduit Inspection Reporting Code of Australia, WSA 05-2013,Water Services Association of Australia (WSAA), a standard score is assigned to each defect using proprietary software such as Wincan Pipe Inspection Software. The scores are aggregated to derive peak and average condition scores. These are also combined into an overall score.
The Conduit Inspection Reporting Code of Australiagradingis consistent with the baseline parameters adopted for condition; however, a grading of 5is assigned to mains in a very poor condition even though the mains are still functional.
Stormwater pipes are normally assessed using Closed Circuit Television (CCTV) inspections. Ideally, all stormwater mains should be inspected by CCTV at regular intervals (10 to 15 years) as part of best industry practice. Where no existing CCTV footage is available or a comprehensive survey is cost-prohibitive, a representative sample of approximately 20% of the network should be used. The sample should contain:

Stormwater pipes of different diameters
Stormwater pipes of different materials
Stormwater pipes where problems have been experienced (e.g. poor hydraulic performance or blockages due to debris)
Stormwater pipes in different areas of the base (to ensure the sample includes stormwater mains from different stages of the base development).

In addition to CCTV inspections, known pipe material and age can be used to estimate stormwater pipe condition and should be confirmed through discussions with the CMS, who may have experience or records indicating the physical condition of certain material types or ages arising from any maintenance undertaken.
The standard asset life for each network component should be considered in the absence of specific data and will require either the age or material type of stormwater pipe (or both), to estimate the condition based on the percentage of the nominal asset life remaining. The nominal asset life for different pipe materials is included in Appendix C.

2.4.2Stormwater Pits, Headwalls, Tidal Flaps and GPTs

The pits, maintenance holes, headwalls and tidal flaps are graded on a scale of 1 to 5, with 1 representing ‘As new’ condition and 5 representing an ‘unserviceable’ condition as outlined in 0 (structural) and Table 2-3 (serviceability). Tidal flaps are assessed using the pit covers condition description. Headwalls are assessed using the pit walls condition descriptions.

Table 2-3Structural condition for pits, headwalls, tidal flaps and GPTs