Maribyrnong City Council – Drainage Data Collection and Revaluation
The provision of municipal stormwater drainage network data collection and revaluation, to enable the collection of a complete inventory to update Council’s GIS, financial and Assets databases.
Drainage Data Collection and Revaluation
Background
The provision of municipal stormwater drainage network data collection and revaluation, to enable the collection of a complete inventory to update Council’s GIS, financial and Assets databases.
The contract also required the identification of both structural and serviceability issues, as well as identification of areas requiring further investigation.
Objectives
The project had two main requirements:
1. The collection and verification of the stormwater drainage network
- Verification of existing known assets, including location, condition and attribution
- Location, GIS mapping, condition and attribution of additional assets
2. The revaluation of Council’s stormwater drainage network
Scope of Services
The data collection was undertaken throughout the entire Maribyrnong LGA.
Specific Requirements
Council supplied digital drainage data, which show the approximate location of the known drainage network, including pits, pipes, and end walls.
The specification required the following tasks to be undertaken:
- Carry out a detailed analysis of the supplied drainage data to determine suitability for use during the field inspection process
- Carry out a physical inspection of each pit within roadways and easements and each end-wall at culverts, inlets and outfalls, to verify locations shown in the existing data
- Identify and record any additional pits and drainage lines found that were not shown in the existing data
- Lift the pit lids and inspect the pits identifying size, depth, type, material, condition, lid condition, litter traps, steps/ladders, steps/ladders condition, internal and external pit photos
- For addition assets, allocate unique pit IDs and pipe IDs
- Identify pipes entering and exiting the pit including size (diameter), material, invert levels, direction of flow, pit IDs of upstream and downstream pits, and visible pipe condition, upstream and downstream pipe photos
- For culverts, inlets and outfalls, identify size, type and material of the end-walls and pipes as well as the direction of flow
- Identify pits which could not be accessed
- Report any damage or blockages in the drainage network
- Revalue, at fair value, all existing and new drainage assets inspected as part of this project
Methodology
Pit locations were surveyed using RTK GPS providing high horizontal and vertical accuracy. Pits and pipes were linked and fully attributed using AssetMap software and Motion tablet computers. Pipe connectivity and condition were assessed using custom built zoom cameras.
All accessible pits and pipe were inspected to ensure complete network coverage.
Traffic management plans and traffic control was supplied by Council’s incumbent contractor.
The valuation was undertaken in accordance with Australian Accounting Standards. A Revaluation, rather than Cost, approach was adopted to determine the Fair Value for the stormwater class of infrastructure assets. In addition, a Greenfields based approach was applied to determining the valuation as directed by Council.
Deliverables
The project deliverables included:
- Asset data in ESRI Shapefile format in the projection/datum GDA 94/MGA94 Zone 55 to allow compatibility with Council’s GIS data
- Asset images included internal & external pit photos, and upstream & downstream pipe photos
- Project report in PDF format
- Final survey and valuation report in Excel format
