Surface Development Guideline 4

Guideline 4 applies to properties that are likely to be undermined in the future with subsidence-induced ground movements.

Development that complies with this Guideline will generally accommodate the following subsidence-induced ground movements: 

Allowable residential construction

Guideline 4 allows for a single residential building that (a) is not a dual occupancy or unit development and (b) conforms with the following description:
Single storey clad frame residential building erected on reinforced concrete strip footings or waffle raft slab designed and constructed to comply with AS2870-2011 for a minimum Class H2 site classification. Site classification “P” for Mine Subsidence is to be ignored for these structures. Maximum height of foundation brickwork 1.5m.

• These improvements are limited to a maximum length of 18 metres and a maximum footprint of 250m2.
• The buildings are to be designed and constructed in accordance with the current editions of AS1684, AS2870-2011, AS3600, AS3700, AS4773, the National Construction Code, and applicable Australian Standards.
• The gradients on wet area floors and roof gutters shall be increased to ensure that they remain serviceable as mining occurs.

All services and external works shall be designed and constructed to accommodate:

Flexible joints in pipes shall be designed to comply with AS2870-2011 for a minimum Class H2 site classification to accommodate curvature in any plane, coupled with tensile or compressive strain.
Branches, bends and valve stems shall be protected by flexible wrapping or shrouds to prevent shearing of the pipes as ground movement occurs. Flexible joints shall be provided where pipes are connected to chambers or gullies.

Prohibited works 

The following works are not permitted under this Guideline:

• Integral retaining walls
• Basements (including partial basements where one or more walls acts as a retaining wall)
• Suspended, drop edge or stepped slabs
• Masonry internal walls

Commercial buildings or applications for more than two separate residential buildings require assessment by Subsidence Advisory in accordance with its Merit Assessment Policy

Other allowable additions and improvements

The below types of additions and improvements are also permitted on properties subject to Guideline 4 provided they are designed such that their connections to existing structures are articulated/flexible and any finished roof, walls and floors are not contiguous with the existing structures:

• Balconies, decks, patios, pergolas, terraces and verandas. 
• Driveways and hard stand spaces.
• Fences. 
• Swimming pools (concrete or fiberglass) subject to the below:
  1. Limit of 8m length unless the parameters detailed in this section are designed for
  2. Any wet edge/infinity is adjustable and designed with sufficient freeboard to ensure that it remains operational within the parameters detailed in this section.

Exempt developments

In addition to the above, Subsidence Advisory has exempted some minor construction works from requiring approval under s22 of the Act.

For a full list of exempt developments, please refer to Subsidence Advisory’s Exempt Development list. 

Proposed developments that do not comply with Guideline 4

Applications for proposed improvements that do not comply with the Guideline assigned to the property may be assessed under Subsidence Advisory’s Merit Assessment Policy. 

Who can assess whether development complies with Guideline 4

Applications for proposed development that complies with this Guideline must be assessed by Subsidence Advisory.

Disclaimer

Please note that Subsidence Advisory’s Surface Development Guidelines are subject to change.