Base Engineering Assessment Program Stormwater Systems

Data Collection

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. 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 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:
   

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  Each kerb inlet pit
  
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  Each field inlet pit
  
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  Each maintenance hole
  
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  Each headwall and endwall
  
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  Each section of stormwater main (between pits or maintenance holes)
  
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  Each outwall/tidal flap
  
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  Each open lined drain
  
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  Each major unlined flood channel
  
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  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. 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.
    

2. Stormwater Network Assessment

   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:
   

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  Engineering Development Standards prepared by the local government in which the base is located, or alternatively AS3500.3 Stormwater Drainage
  
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  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).
  

1. 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:
   

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  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)
  
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  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.
  

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