Base Engineering Assessment Program
Stormwater Systems
Reticulated Services Assessment Manuals
December 2013
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 Government Information Security Manual, August 2011
MFPE
Defence Manual of Fire Protection Engineering
MIEE
Defence Manual 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
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Acronym/Abbreviation
Description
HPC
Heterotrophic Plate Count
LiDAR
Light Detection and Ranging
L/s
Litres per second
P&ID
Process and Instrumentation Diagrams
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
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Table of Contents
Glossary
ii
1
Stormwater Systems
1
1.1
1.3
1
3
2
3
4
Overview
Data Collection
Stormwater Network Assessment
4
2.1
2.2
2.3
2.4
2.5
4
4
5
5
8
Description
Data Collection
Capacity Assessment
Condition Assessment
Compliance Assessment
Flood Immunity
10
3.1
3.2
3.3
3.4
3.5
10
10
10
10
11
Description
Data Collection
Capacity Assessment
Condition Assessment
Compliance Assessment
Water Quality
12
4.1
4.2
4.3
4.4
4.5
12
12
12
13
14
Description
Data Collection
Capacity Assessment
Condition Assessment
Compliance Assessment
Tables
Table 1-1
Table 2-1
Table 2-2
Table 2-3
Table 2-4
Table 2-5
Table 3-1
Table 3-2
Table 3-3
Table 4-1
Table 4-2
Engineering Service assessment parameters
Defence Clauses for Function Design Briefs
Structural condition for pits, headwalls, tidal flaps and GPTs
Serviceability condition for pits, headwalls, tidal flaps and GPTs
Structural condition for open channels
Serviceability condition for open channels
Serviceability condition for flow paths
Defence Clauses for Function Design Briefs
Melbourne water hazard classes and criteria
Structural condition - water quality improvement devices
Serviceability condition – water quality improvement devices
2
5
7
7
8
8
11
11
11
13
13
Appendices
Appendix A
Stormwater Data Required cChecklists
Appendix B
Stormwater Master Spreadsheet – Refer Electronic File
Appendix C
STANDARD ASSET LIFE – STORMWATER ASSETS
Appendix D
Stormwater Data Collection Forms – Refer Separate Electronic Files
Appendix E
Stormwater system QUESTIONNAIRE
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Stormwater Systems
1.1
Overview
1.
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).
2.
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.
1.1.1
Summary of the assessment process
3.
The assessment process is 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).

Phase Three—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.
4.
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.
5.
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.
6.
The assessment criteria used to assess each utility engineering service status for capacity, condition
and compliance is provided in Table 1-1.
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Table 1-1
Engineering Service assessment parameters
Assessment parameters used to establish the service status
Capacity
Condition
Compliance
Exceeded
Unserviceable
Non-Compliant
100% of service capacity has been
used.
Manhole/pit capacity exceeded and
overland flooding experienced at
depth greater than 100 mm.
Not capable of functioning as
intended, obsolete equipment /
components, unable to be maintained
– requiring full replacement / upgrade.
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
Fair
75%>x<100% of service capacity
has been used. Likely to be noncompliant 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.
Deterioration is obvious and there is
some serviceability loss.
Within Limits
Good
Compliant
<75% of service capacity has been
used.
All manholes not falling within the
above categories.
Signs of deterioration evident,
serviceability would be impaired very
slightly.
Design complies with applicable
design guidelines, Australian
Standards and/or Defence
Policy requirements.
As New
No visible sign of deterioration,
recently constructed / installed, or
recently rehabilitated back to new
condition.
1.2
Overall Assessment Outcomes
1.2.1
Stormwater assessment standards and guidelines
7.
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 (http://www.defence.gov.au/im/policy/technical/standard_inclusions/civil_feb06.doc)

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.
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1.3
Data Collection
1.3.1
Data checklists / Data required tables
8.
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).
1.3.2
Master spreadsheets
9.
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 longterm 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.
10.
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.).
1.3.3
Risk and criticality
11.
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.
12.
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).
13.
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.
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2
Stormwater Network Assessment
2.1
Description
1.
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.
2.
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.
3.
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 (http://www.defence.gov.au/im/policy/technical/standard_inclusions/civil_feb06.doc)

Australian Rainfall and Runoff 1987 (Format and Presentation update only for 2000).
2.2
Data Collection
4.
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.
5.
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).
6.
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.
7.
Pipe and pit or maintenance hole 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.
8.
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.
9.
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)
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
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.
2.3
Capacity Assessment
2.3.1
Stormwater pipes and pits
10.
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.
11.
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 2-2.
Table 2-2
Defence 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.
12.
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.
2.4
Condition Assessment
2.4.1
Stormwater Pipes
13.
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).
14.
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.
15.
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.
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16.
The Conduit Inspection Reporting Code of Australia grading is consistent with the baseline
parameters adopted for condition; however, a grading of 5 is assigned to mains in a very poor condition even
though the mains are still functional.
17.
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 costprohibitive, 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).
18.
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.
19.
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.
2.4.2
Stormwater Pits, Headwalls, Tidal Flaps and GPTs
20.
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 2-4 (serviceability). Tidal flaps are assessed using the pit covers condition description. Headwalls
are assessed using the pit walls condition descriptions.
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Table 2-3
Structural condition for pits, headwalls, tidal flaps and GPTs
Asset
Grade
Pit/
Maintenance
Hole s Structure
(includes wall
and base)
Maintenance
Hole Cover
1
As new
2
Good - Minor erosion/hairline cracks but no effect on structure
3
Fair - Significant erosion, small amounts of concrete loose or missing, or cracks less than 5
mm – minor repair required, but structural integrity not compromised
4
Poor - Severe erosion/significant amounts of concrete loose or missing, or cracks between
5 and 15 mm– requires replacement or major repair, but not immediately
5
Very poor - Structure unsafe, major amounts of concrete loose or missing, or cracks
greater than 15 mm – requires replacement as soon as possible
1
As new
2
Minor wear but no effect on structure
3
Significant erosion/wear or slight deformity – minor repair required, but structural integrity
not compromised. Presents no appreciable health and safety risk.
4
Severe wearing/corrosion or major deformity, or poses minor health and safety risk
5
Cover missing or requiring replacement as soon as possible due to structural integrity loss
or significant health and safety risk
1
As new
2
Good - Minor erosion/hairline cracks but no effect on structure
3
Fair - Significant erosion, small amounts of concrete loose or missing, or cracks less than 5
mm – minor repair required, but structural integrity not compromised
4
Poor - Severe erosion/significant amounts of concrete loose or missing, or cracks between
5 and 15 mm– requires replacement or major repair, but not immediately
5
Very poor - Structure unsafe, major amounts of concrete loose or missing, or cracks
greater than 15 mm – requires replacement as soon as possible
1
As new
2
Good - Minor wear but no effect on cover structure.
3
Fair - Significant erosion/wear or slight deformity – minor repair required, but structural
integrity not compromised. Presents no appreciable health and safety risk.
4
Poor - Severe wearing/corrosion or major deformity, or poses minor health and safety risk
– requires replacement or major repair
5
Very poor - Cover missing, requires major repair/replacement as soon as possible due to
structural integrity loss or significant health and safety risk
1
As new
2
Good – no visible defects
3
Fair - Minor corrosion of step irons
4
Poor- A few step irons requiring replacement/repair but not immediately/minor health and
safety risk
5
Very poor - No step irons and requires them/ Most step irons requiring replacement as
soon as possible/major health and safety risk
Kerb Inlet Lintel
Cover
(Cover/Apron or
Tidal Flap)
Step Irons
Table 2-4
Description
Serviceability condition for pits, headwalls, tidal flaps and GPTs
Pit and structure serviceability
1
3
5
No cleaning required
Cleaning expected to be required within 3 months
Cleaning required
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2.4.3
Open Lined Channels and Unlined Channels
21.
The condition assessment of open lined channels and unlined channels is based on Table 2-5 and
Table 2-6.
Table 2-5
Structural condition for open channels
Open Channel Structural condition
1
As new
2
Good - Minor erosion/hairline cracks but no effect on structure
3
Fair - Significant erosion, small amounts of lining loose or missing, or cracks less than 5 mm – minor repair
required, but structural integrity not compromised
4
Poor - Severe erosion/significant amounts of lining loose or missing, or cracks between 5 and 15 mm– requires
replacement or major repair within 3-5 years
5
Very poor - Structure unsafe, major amounts of lining loose or missing, or cracks greater than 15 mm – requires
replacement within next 3 years
Table 2-6
Serviceability condition for open channels
Serviceability - Vegetation
1
3
5
Vegetation has no effect on open conduit
Remediation expected to be required within 3 months
Overgrown, appears choked with weedy vegetation, waterway affected by thick plants and shrubs within
channel – Remediation required
Serviceability - Cleaning
1
3
5
No cleaning required
Cleaning expected to be required within 3 months
Cleaning required
22.
Pits and maintenance holes are normally assessed through physical inspections from the surface
only (i.e. no man entry into the holes). Thorough inspections of the holes can be undertaken when the covers
are removed for CCTV inspections, or can be undertaken in conjunction with maintenance staff by removing
the cover (the number of operators required to remove the cover is related to the size, configuration and
weight of the cover). Mechanical lifting is normally required to remove the cover.
23.
While the majority of covers can be assessed relatively simply from surface inspections, the internal
condition will generally only be assessed for a representative sample of pits and maintenance holes
(approximately 20%-50% of the network), as a complete inspection is time and cost prohibitive. The sample
should be similar to that outlined for stormwater pipes.
24.
If a cover cannot be removed or the maintenance hole is buried, the condition is considered to be
unserviceable (5) as it cannot function as intended.
2.5
2.5.1
Compliance Assessment
Stormwater Pipes and Pits
25.
Compliance is assessed against the following standards and guidelines:

Engineering Development Standards prepared by the local government in which the base is located

AS3500.3 Stormwater Drainage

Standard Clauses on Civil Engineering for Inclusion in Functional Design Briefs, Department of
Defence (http://www.defence.gov.au/im/policy/technical/standard_inclusions/civil_feb06.doc
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26.
The capacity and compliance of piped drainage systems are intrinsically linked. Pipes and pits are
considered non-compliant if they cannot adequately convey the 1 in 10 year ARI.
27.
Pits should also be assessed for compliance with AS3500 requirements regarding safety and
access. AS3500 notes minimum pit cover sizes and minimum internal dimension for man access into the pit
for cleaning and maintenance. The cover, internal dimensions and the arrangement of step irons should be
assessed as part of the investigations.
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3
Flood Immunity
3.1
Description
1.
The pit and pipe stormwater network is required to accommodate a 1 in 10 year ARI storm event.
Overland flow paths (which usually consist of roads, car parks and open channels) are designed to
appropriately convey overland flows in excess of this event. The 100 year ARI storm event is an accepted
design limit for overland flow paths (and is used by the local authority in this instance and the governing
criteria).
3.2
Data Collection
2.
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.
3.
Data require for the flood immunity assessments includes site surface levels, layout plans for the
site, details of any detention basins, ponds, weirs etc., previous hydraulic modelling studies and any flood
hazard studies. Projections of future sea level rises will be required for coastal bases.
4.
The extent of available data should be confirmed during Phase One to establish what studies have
already been undertaken, what data is available and where data gaps exist.
5.
Discussions with base staff will provide some indication of recent flood events.
6.
Accurate ground level data is required for flood modelling. The availability of LiDAR data for each
site should be verified during Phase One, as historical survey information may be sufficient to complete the
assessment.
3.3
Capacity Assessment
7.
Where recent flood studies have been undertaken, these will be reviewed and used as a basis for
assigning a capacity grade.
8.
If previous studies are limited, do not exist, or do not address the relevant design criteria, then
hydraulic modelling will be undertaken using an appropriate software package for the 10, 50 and 100 year
ARI design storm events. The analysis will identify areas of localised ponding and flood inundation.
3.4
Condition Assessment
9.
Condition assessments will be undertaken on flow paths within stormwater catchments and will
assess whether barriers or obstructions to stormwater flow exist. A serviceability grading will be assigned to
each major flow path or catchment. This will be undertaken at a high level as the response will typically
involve maintenance activities such as vegetation clearing, which is relatively low cost.
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10.
The condition assessment criteria are shown in Table 3-7.
Table 3-7
Serviceability condition for flow paths
Serviceability - Vegetation
1
3
5
Vegetation has no effect on open conduit
Remediation expected to be required within 3 months
Overgrown, appears choked with weedy vegetation, waterway affected by thick plants and shrubs within
channel – Remediation required
Serviceability - Debris
1
3
5
No significant debris in flow path
The extent of debris/ barriers may have limited impact on overland flow
Debris or barriers exists within the flow path which will significantly impact on run-off - remediation required
3.5
Compliance Assessment
11.
The Defence Clauses for Function Design Briefs (Design Brief) provide a benchmark for the capacity
and compliance of the stormwater system. An extract is included in Table 3-8.
12.
Compliance is assessed by undertaking hydraulic modelling for the 10, 50 and 100 year ARI events.
Table 3-8
Defence 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.
13.
Flood Hazard Classes, as outlined in Table 3-9 (Melbourne Water) should also be used to evaluate
flood hazard within the study area. A risk class of moderate (2) or above is indicative of the point at which
operations by able bodied adults would become impeded. This is also the approximate threshold at which
normal passenger cars begin to float.
Table 3-9
Melbourne water hazard classes and criteria
Hazard Class
Hazard Criteria
Grade
Low
Depth * Velocity < 0.2 m/s2 and Depth < 0.2 m
1
Low-Moderate
Depth * Velocity < 0.4 or Depth < 0.4 m
2
Moderate
Depth * Velocity < 0.6or Depth < 0.6 m
3
Moderate-High
Depth * Velocity < 0.84 or Depth < 0.84 m
4
High
Depth * Velocity > 0.84 or Depth > 0.84 m
5
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4
Water Quality
4.1
Description
1.
Stormwater can be a major source of contaminants into water courses including nutrients, heavy
metals and pathogens. Over recent years local governments have required the installation of water quality
improvement devices in new developments. These typically include:

Trash racks

Gross pollutant traps (GPTs)

Constructed (artificial) wetlands

Gully Pit Baskets and Nets.
2.
The water quality assessment should be based on the requirements of:

State Government environmental protection policies

Engineering Development Standards prepared by the local government in which the base is located

Water Sensitive Urban Design (WSUD) Principles

Standard Clauses on Civil Engineering for Inclusion in Functional Design Briefs, Department of
Defence (http://www.defence.gov.au/im/policy/technical/standard_inclusions/civil_feb06.doc)

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.
4.2
Data Collection
3.
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.
4.
Data required for water quality assessments includes details of any water quality improvement
devices including type, flow, function, age, by-pass facilities, manufacturer, model, dimensions, design
capacities, maintenance practices. Other data will include water quality management plans, reports/ studies
into stormwater quality and receiving waters, monitoring results, maintenance records
4.3
Capacity Assessment
5.
The capacity will assessment will include:

Assessing the performance of existing water quality improvement devices based on any monitoring
data

Comparing actual loading against the design or rated capacity.
6.
The capacity assessment is only relevant to installed water quality treatment devices. If no devices
are installed (i.e. direct outflow), then the capacity assessment is not relevant.
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4.4
Condition Assessment
14.
Water quality improvement devices are graded on a scale of 1 to 5, with 1 representing ‘As new’
condition and 5 representing an ‘unserviceable’ condition as outlined in Error! Reference source not
found.Table 4-10 (structural) and Table 4-11 (serviceability).
Table 4-10
Structural condition - water quality improvement devices
Asset
Grade
1
2
Gross Pollution
Trap (GPT)
Trash racks/
Gully Pit
Baskets
Artificial
Wetlands
Table 4-11
Description
5
As new
Good - Minor erosion/hairline cracks but no effect on structure
Fair - Significant erosion, small amounts of concrete loose or missing, or cracks less
than 5 mm – minor repair required, but structural integrity not compromised
Poor - Severe erosion/significant amounts of concrete loose or missing, or cracks
between 5 and 15 mm– requires replacement or major repair, but not immediately
Very poor - Structure unsafe, major amounts of concrete loose or missing, or cracks
greater than 15 mm – requires replacement as soon as possible
1
As new
2
Good - Minor wear but no effect on cover structure.
3
Fair - Significant erosion/wear or slight deformity – minor repair required, but structural
integrity not compromised. Presents no appreciable health and safety risk.
4
Poor - Severe wearing/corrosion or major deformity, or poses minor health and safety
risk – requires replacement or major repair
5
Very poor - Cover missing, requires major repair/replacement as soon as possible due
to structural integrity loss or significant health and safety risk
1
As new
2
Good - Minor erosion/ no effect on structure
3
Fair - Significant erosion, small amounts of lining loose or missing, or cracks less than 5
mm – minor repair required, but structural integrity not compromised
4
Poor - Severe erosion/significant amounts of lining loose or missing, or cracks between
5 and 15 mm, – requires replacement or major repair within 3-5 years
5
Very poor – Unlined sides of structure are un-formed, structure unsafe, major amounts
of lining loose or missing, or cracks greater than 15 mm – requires replacement within
next 3 years
3
4
Serviceability condition – water quality improvement devices
Asset
Grade
Description
1
Very good condition – no cleaning required
3
Fair condition
Some debris has accumulated - cleaning expected within 3 months
Vegetation becoming overgrown – some harvesting required within 3 months
5
Unserviceable
Structure is not providing its function as excessive debris has accumulated – cleaning
required
Overgrown vegetation and/or a number of dead plants. Limited hydraulic capacity and/or
treatment capability – remediation required
GPT/
artificial
wetlands
7.
The condition assessment is only relevant to installed water quality treatment devices. If no devices
are installed (i.e. direct outflow), then the condition assessment is not relevant.
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4.5
Compliance Assessment
8.
The following criteria are used to assess compliance of the water quality improvement devices:

State Government environmental protection policies

Engineering Development Standards prepared by the local government in which the base is located

Water Sensitive Urban Design (WSUD) Principles

ANZECC: Australia and New Zealand Environment and Conservation Council, Australian and New
Zealand Guidelines for Fresh and Marine Water Quality, October 2000.
9.
The level of compliance will take into account:

Whether any base development has occurred in recent years which should have been subject to
contemporary water quality management practices. Existing base arrangements are deemed to be
compliant until any new developments are proposed

Capacities and loadings of existing water quality improvement devices

The level of maintenance on existing devices

Any specific requirements placed on the base by the state environmental regulator or local
government.
10.
Compliance with the Defence precinct’s stormwater quality management plan should be assessed.
Where water quality results are available for outlets, the water quality reading should be compared to the
relevant ANZECC guideline limits, based on the classification of the area where the water is discharged (i.e.
local creek, RAMSAR wetland , etc.).
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APPENDIX A
STORMWATER DATA REQUIRED
CHECKLISTS
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Category
Required Data
Spatial Data
Base Development
History
Ground levels and topography e.g. LIDAR
History of base development, including changes
since commissioning
Y
Spatial Data
GIS, CAD design plans, site survey, asconstructed drawings and equipment databases
Y
Analysis Data
Hydraulic Model: Data Input (GIS) including
network details, elevations and demand nodes,
and Modelling Outputs (pipe flood depths)
Y
Y
Y
Analysis Data
Analysis Data
Network
Y
Y
Analysis Data
Network
Y
Y
Network
Y
Y
Analysis Data
Operations and
Maintenance
Y
Y
Y
Y
Sub-service
Capacity
Condition
Compliance
All
Y
Y
Y
All
Y
Y
Y
All
Y
Y
Network
Y
Network
Network
Y
Y
Network
Y
Network
Operations and
Maintenance
Operations and
Maintenance
Network
Y
Y
Y
Spatial Data
Network
Network
Y
Y
Y
Y
Spatial Data
Analysis Data
Overland flow
Y
Y
Y
Spatial Data
Overland flow
Y
Overland flow
Overland flow
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Analysis Data
Y
Y
Data title
Records of network collapses or flooding
Network Design Capacity
Pipeline condition reports or inspection data e.g.
CCTV
Pit condition reports or inspection data
Operations and maintenance data / maintenance
records
Previous operational issues (flooding incidents,
blockages, collapses, etc.)
Operations and Maintenance (O&M) Manuals
Survey data including horizontal and vertical
alignment, surface levels, depths, invert levels
and location
Pipelines - diameter, material, age
Catchment and sub-catchment areas
Details of any detention basins, pond, tanks,
weirs, discharge structures and outlet points
Existing model data or flood report data
Analysis Data
Condition reports/details for overland flow paths
or physical inspection details of overland flow
paths and channels
Analysis Data
Hydraulic Model: Data Input (GIS) including
network details, elevations, catchment/subcatchment data, and Modelling Outputs (10, 20
and 100 year ARI) as well as other specific local
1
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authority events.
Overland flow
Y
Overland flow
Y
Water quality
Y
Y
Analysis Data
Water quality
Y
Y
Analysis Data
Water quality
Y
Y
Analysis Data
Water quality
Y
Environment
Water quality
Y
Environment
Y
Operations and
Maintenance
Water quality
Y
Safety and Access
Operations and
Maintenance
Y
Water quality
Y
Spatial Data
Water quality
Y
Spatial Data
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Flood hazard risk assessment
Flooding incidents
Previous design reports for flood immunity
(overland flow discharge) or network capacity
(piped discharge)
Water quality management plan
Discharge water quality and quantity into
potential sensitive environments
Reports on water contamination / environmental
issues on base
Potential points of contamination, isolated or
protected
Maintenance records - Water quality
management devices
Water quality management devices - Details
including type, flow, function, age, bypass
arrangements
Mechanical equipment (i.e. treatment
equipment, GPTs, stormceptors, etc.) –
Manufacturer, model, age, operating curves,
motor size, control philosophy
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APPENDIX B
STORMWATER MASTER
SPREADSHEET – REFER ELECTRONIC
FILE
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APPENDIX C
STANDARD ASSET LIFE –
STORMWATER ASSETS
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Useful Life
Range (yrs)
Typical Life
(yrs)
Pipes – Concrete
60 - 100
90
Pipes – PVC
60 - 80
70
Pipes – Polyethylene
60 - 80
70
Pipes – Vitreous clay
80 - 100
90
Pipes – corrugated steel
40 - 70
60
Open drains – lined
60 – 100
90
Open drains – unlined
80 – 150
120
Culverts – corrugated steel
40 - 70
60
Pits – concrete
60 - 100
90
Headwall/ Endwall (outlet)
60 - 100
90
Infrastructure component
Stormwater Network
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APPENDIX D
STORMWATER DATA COLLECTION
FORMS – REFER SEPARATE
ELECTRONIC FILES
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APPENDIX E
STORMWATER SYSTEM
QUESTIONNAIRE
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Reference
Questions
Comments
General Questions
Who is responsible for management of the stormwater network?
1
a
Operation and maintenance?


collection network
water quality improvement devices
b
Compliance (e.g. water quality y)
c
What contractors are involved and what is the scope of their services?
2
Check that the relevant staff/ contractors are on the interview schedule
3
What do you see as the biggest risks associated with the stormwater network?
4
Have you experienced any flooding events? What were the impacts?
5
Does the stormwater discharge to an environmentally sensitive area?
6
Do you have any contingency plans in place?
7
Do you have any major asset renewals planned over the next few years?
Catchments
1
Please describe the topography and flow paths within the base (mark up a site plan)
2
Is there any flow from upstream of the base?
3
Has any flow monitoring been undertaken on site?
4
Have any stormwater hydraulic models been developed for the site?
5
Are you aware of any flood studies that have been undertaken in your area by other organisations (state or local
government)?
Network Configuration
1
Can you describe the stormwater network?
a
Are there any channels and where do they exist?
b
Where does it discharge to? (how many discharge points and confirm the local authority/ water utility)
c
Can you draw up a simple schematic of the system?
d
Are there any areas of the site that do not have a stormwater collection network?
2
Is the site services plan spatially accurate?
a
What is the level of confidence in the data?
b
Does the plan include any recent developments (extensions, augmentations or renewals)
c
Has the location and level of the pits been surveyed (and when)?
d
Are the invert levels known and what is the level of confidence/accuracy?
What are the ground conditions across the various parts of the base – clay, sand, rock etc. ?
3
Network Development
1
What is the history of the system?
a
When was it originally built and have there been any major additions over the years?
b
Are there any new areas that may not be on the site services plan?
Service Levels
1
What is the level of satisfaction with the stormwater system?
2
Are there any areas subject to stormwater inundation/ flooding? What is the frequency and impacts?
3
What is the cause of this flooding? network capacity? building levels? outlet constraints?etc?
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Reference
Questions
Comments
4
Have any remedial actions been undertaken (successful/ less successful)
5
Are there any known network capacity issues?
6
Have you undertaken any hydraulic modelling to assess the capacity of the system? Can we obtain a copy of the model
and any accompanying reports?
Pipes and Channels
What materials are used?
1
a
Do you have a feel for the proportion of each (i.e. what is the most common material)
b
Were they generally installed at a similar time?
c
Are the materials accurately reflected on the site services plan?
2
Are pipe diameters accurately shown on site services plan?
3
Have there been any widespread recent works such asrelining or replacements?
4
Do you know what sort of condition the pipes and are in?
a
Have you undertaken any CCTV inspections and/or pit/ maintenance hole inspections
b
Can you provide us with the relevant reports
c
Are there any known problem areas? (sketch on plan)
d
What is the nature of these problems (blockages, breaks) what is the likely cause? Is it related to pipe age, material,
depth or location or are the stormwater mains beneath heavily-treed areas
e
Do you have any reports prepared on these problems?
f
How have you addressed these problems in the past – what has succeeded, what has failed?
g
Are failures recorded in DEMs or other system?
Do you undertake any planned maintenance e.g.
5
a
Proactive cleaning/ jetting of pits, pipes and channels
b
CCTV inspections
Do you have any reports on capacity, condition or compliance?
6
Pits and Maintenance Holes
Do you know the condition of the maintenance holes?
1
a
What are the reasons for any poor condition (age, material etc)?
b
How often are they inspected?
c
What material – in-situ concrete or precast?
d
What types of maintenance holes cause you problems
Water Quality
1
Do you have any water quality improvement devices on site?
a
What are they and where are they located?
b
How do they perform?
c
What is the level of maintenance undertaken?
d
Are there any additional devices planned for installation?
2
Have you undertaken any monitoring of stormwater quality or quality of the receiving waters?
a
What were the reasons for the monitoring?
b
Could we please have a copy of the results
Questions for the Local Authority
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Reference
Questions
Comments
1
Any issues in relation to stormwater discharge creating flooding on adjacent sites.
2
Adjacent existing development and future development that may affect flow from external catchments entering or
impacting on the Defence site.
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