Lake Munmorah — Preliminary Site Investigation & Acid Sulfate Soil Assessment
Confluence Environmental completed a Preliminary Site Investigation (PSI) and acid sulfate soil assessment for a 9.7-hectare site at Lake Munmorah, supporting a planning proposal for future residential development.
The engagement brought together contamination assessment and acid sulfate soil advice to identify potential development constraints and establish requirements for further investigation and management.
About the project
The site comprises two existing allotments proposed for rezoning from RU6 Transition to R1 General Residential and C2 Environmental Conservation.
The indicative development included approximately 180–250 residential lots, associated roads, stormwater infrastructure and conservation corridors, subject to planning and design.
Confluence’s role was to assess historical contamination risks and mapped acid sulfate soil constraints at the planning proposal stage.
Preliminary Site Investigation
The PSI combined historical aerial imagery, land title and regulatory searches, a site walkover and targeted soil sampling at 14 locations within the accessible allotment.
The investigation considered potential impacts associated with imported fill, vehicle storage, fuel and chemical handling, and older building materials. Laboratory analysis addressed petroleum hydrocarbons, metals, pesticides and other contaminants relevant to the identified activities.
Confluence interpreted the findings in the context of the proposed residential use and developed recommendations for:
Further investigation of inaccessible areas and unknown fill.
Management of localised impacted material.
Hazardous building materials assessment before demolition.
Construction environmental controls and unexpected finds procedures.
The assessment supported the proposed rezoning, subject to the recommended further investigation and management measures.
Acid sulfate soil assessment
A separate desktop acid sulfate soil assessment examined planning maps, geological and soil landscape information, topography, groundwater records and site observations.
The review identified approximately 3,700 m² of mapped Class 4 acid sulfate soil land within the broader property. Confluence assessed this constraint against the site’s environmental setting and the proposed development concept.
The assessment concluded that acid sulfate soils were unlikely to represent a significant constraint to rezoning. It also identified when targeted investigation would be required as excavation depths, infrastructure and groundwater management requirements were defined.
Clear advice for the next stage
The combined assessment gave the project team a documented basis for progressing the planning proposal while carrying forward the investigation and management requirements for future development.
By assessing contamination and acid sulfate soils together, Confluence provided coordinated advice for subdivision planning, earthworks and conservation areas.
Planning a subdivision or rezoning? Contact Confluence Environmental for contaminated land and acid sulfate soil assessment.