Advice to contractors

Note 7 in the Design Note series on advice to contractors, updated February 2013.

This revised Design Note 7 has additional information in relation to:

  • Collection pits at easement drain connections
  • House drain connections - Standard drawing Numbers 505, 510, 515, 520
  • Cement stabilised backfill to unground stormwater pipes
  • Defects Liability Period
  • When the changes become effective

Subdivision construction

We (the City of Greater Geelong) wish to draw attention to a number of issues relating to the construction of subdivisions.

Contractors will be aware that we have adopted the Infrastructure Design Manual (IDM) as our standard for the design and construction of infrastructure within our municipality and in particular, the standard for civil works in subdivisions. We have developed a set of Design Notes which provide additional information relating to the construction of subdivisions within our boundaries. It is expected that, in the future, these notes will be updated and/or added to as required. Contractors need to be aware that any civil works for subdivisions need to comply with both the IDM and the Design Notes.

We have also formed the Design Notes group. This is an internet group which is used primarily to distribute the Design Notes. Members of the group get notified of any new or updated Design Notes. If you wish to become a member of the group email your request to John Bryce ([email protected]) to become a member, with your email addresses (you can have more than one staff member getting updates) or phone 03 5272 4420.

While the Design Notes are generally about technical aspects of design, the following have particular relevance to contractors:

  • DN 4 – Vehicle Crossovers
  • DN 5 – Administrative Issue
    • 5.5 - CCTV of drains before Statement of Compliance issued
    • 5.11 - Site management
    • 5.12 – Issue of Statement of Compliance

Construction matters to note

The IDM includes a number of standards which some contractors may be unaware of. Contractors should note that the IDM requires that:

  • SD520 - Easement drain connections to be as per standard drawing SD520
    • Use a “Conconect” or similar to connect a house stormwater pipe to an easement drain. Using a “Pan” connector is no longer acceptable. CoGG is currently trialling connecting to “Stormpro” pipes using the combination of a “ProGrommet” and a pan connector.
    • The collection pit is to be as per SD520 – a 450mm x 450mm grated inlet pit. “Doughnuts” are no longer acceptable.
      • Collection pits can be precast concrete or plastic. Grates must be cast iron, galvanised steel or aluminium. Pits and grates must be suitable for light traffic. The pit/grate must have a clear opening of at least 400mm by 400mm and be a minimum of 300mm deep.
      • The “Property Connection” as shown on SD520 shall extend to 200mm clear of the outer edge of the pit.
      • Where the cover over the pipe is less than that required to construct as per SD520, the “T” junction may be omitted. The house connection shall be into the side of the pit, by the plumber, at the time of house construction.
      • The pipework must be a minimum of 100mm dia sewer class PVC
      • All pipework and connections to be to Plumbing Standards AS 3500
    • Backfill to the top of the pipe shall be cement stabilised sand (2% to 4% cement)
  • 505 - House Drain Connection to Kerb & Channel shall be as per SD505 except that:
    • The kerb adaptor shall be galvanised steel that matches the kerb profile
    • The pipe connection shall be a minimum of 100mm dia Sewer class PVC
    • The inspection opening shown in SD505 is to be installed by the plumber during the house construction.
  • SD515 - Street Drain Connection shall be as per SD515 except that:
    • Only one inspection opening is required
    • The pipe connection shall be a minimum of 100mm dia Sewer class PVC
    • Backfill to the top of the pipe shall be cement stabilised sand (2% to 4% cement)
  • SD510 - House Drain Under Road Pavement shall not be used without prior approval.
  • Hold points and witness points are observed – IDM Appendix E, first page (attached). Contractors must ensure that Council inspectors have the opportunity to inspect work at all of these points. This is a minimum – there may be others required. Council inspectors may not necessarily attend at all of the points but they must be made aware, in advance, when hold points are approaching.
  • Stormwater drainage pipes are to be inspected when they are bedded/haunched and before the trenches have been backfilled. Contractors are to ensure that inspectors are advised when pipes have been laid so that inspections can be carried out prior to backfilling
  • All new residential footpaths to be 125mm thick – SD’s 205,210, 240, 245
  • The Defects Liability Period for new subdivisions is 12 months from the date of Practical Completion and a 5% bond will be held for this period. The Defects Liability Period is as described in the IDM Section 8. Any items/works, noted at the time of Practical Completion as being outstanding, are still to be completed within 3 months from the time of Practical Completion.

Directions to become effective as of 1 January 2013

It should be noted that most of the directions made in this Design Note are not new or changes, but are taken directly from the IDM which we adopted in 2009. These directions will effect works/subdivisions that had not been approved as at 1 January 2013.


  1. Appendix E – Infrastructure Design Manual – Council Inspections and Hold Points
  2. Easement Drain Connection – SD 520

Attachment 1

Infrastructure Design Manual - Appendix E - Council Inspections & Hold Points
List of Council inspections (hold points) and witness points
Click to Enlarge Image

Attachment 2

Easement Drain Connection - SD 520
Diagram showing easement drain connection
Click to Enlarge Image

Page last updated: Friday, 7 February 2020