Stormwater Systems Overview

Stormwater Systems

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. 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:
   

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  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.
  
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  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).
  
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  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.
   

1. 
   Engineering 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 Policy requirements.
   	As New No visible sign of deterioration, recently constructed / installed, or recently rehabilitated back to new condition.

1. 
   Overall Assessment Outcomes
   

   1. Stormwater assessment standards and guidelines

7. 
   The standards, guidelines and legislative requirements relevant to a stormwater assessment include:
   

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

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