ASSMP (Acid Sulfate Soils Management Plan)
ASSMP is the Acid Sulfate Soils Management Plan required by NSW councils on Class 1/2 land and on Class 3/4 land where excavation exceeds the trigger depth.
Ask Chalkline about this →An ASSMP is an Acid Sulfate Soils Management Plan, a document a NSW council requires before granting development consent on land where acid sulfate soils (ASS) may be disturbed. It is prepared in accordance with the NSW Acid Sulfate Soils Manual (NSW EPA, 1998) and lodged with the DA.
When an ASSMP is required
Triggered by the ASS class mapped on the property’s Section 10.7 planning certificate:
| ASS class | When the ASSMP is triggered |
|---|---|
| Class 1 | Any works that break the natural ground surface or lower the water table |
| Class 2 | Any works below natural ground surface or lowering the water table |
| Class 3 | Excavation deeper than 1 m below natural ground surface |
| Class 4 | Excavation deeper than 2 m below natural ground surface |
| Class 5 | Within 500 m of Class 1, 2, 3 or 4 land, where works likely to lower the water table |
Class 1 and Class 2 land is also excluded from all complying development codes under SEPP (Exempt and Complying Development Codes) 2008. The CDC pathway closes; only a DA with ASSMP is available.
Required content
The NSW Acid Sulfate Soils Manual sets the minimum ASSMP scope:
- Site description (ASS class, depth to mapped ASS, water table, soil profile).
- Proposed works that may disturb ASS (excavation depths, dewatering, drainage).
- Soil testing program and lab results.
- Treatment plan (typically agricultural lime application at calculated dose rates).
- Stockpile and disposal procedures.
- Monitoring during and post-works.
- Rehabilitation plan.
- Qualifications of the preparer.
The ASSMP must be prepared by a qualified environmental practitioner (typically a geotechnical engineer or environmental consultant with ASS experience).
Process
- Get the Section 10.7 planning certificate before pricing or design; check for the ASS class.
- If triggered, engage an environmental consultant before lodging the DA.
- Submit the ASSMP with the DA; council will not grant consent without it on triggered land.
- Allow time for council review of the ASSMP (often 4-8 weeks added to the DA timeline).
- Once consent is granted with ASSMP conditions, do not start excavation until the ASSMP is fully approved and the consent conditions are met.
Cost and time
- ASSMP preparation: typically $3,000 to $12,000 depending on site complexity and testing scope.
- Lime treatment: variable; can add $5,000 to $30,000+ to earthworks for a small residential block.
- DA timeline: ASSMP review commonly adds 4-8 weeks.
See acid sulfate soil in NSW for the full builder-facing procedure.
Also known as: Acid Sulfate Soils Management Plan, ASS management plan.
Category: Approvals / NSW / environmental.
Related
See also
Last updated: 2026-05-16. Verified: 2026-05-16.