North Richmond — Preliminary & Detailed Site Investigations for a Commercial Precinct
Confluence Environmental completed a Preliminary Site Investigation (PSI) and Detailed Site Investigation (DSI) for a proposed commercial precinct at North Richmond, within the Hawkesbury region of NSW.
The investigations supported a planning proposal and development application for an approximately 2-hectare development footprint within a broader 10-hectare rural property.
About the project
The proposed redevelopment brings together hospitality, retail, health and recreation uses, including a function centre, service station, medical centre, pub, fast food restaurant and gym, with associated access roads, parking and hardstand areas.
Confluence’s role was to investigate potential contamination associated with historical rural activities and structures, assess suitability for the proposed commercial use and identify environmental management requirements for construction.
Project at a glance:
Development footprint: Approximately 2 hectares.
Broader property: Approximately 10 hectares.
Potential contamination sources: Six areas of environmental concern identified through the PSI.
Detailed investigation: 38 soil sampling locations, supported by surface water and sediment sampling.
Deliverables: PSI and DSI supporting the planning proposal and development application.
Preliminary Site Investigation
The PSI combined historical aerial imagery, land title searches, regulatory records and a site walkover to establish the property’s land-use history and identify potential contamination sources.
The review identified rural and grazing activities dating from at least the 1960s, together with an existing dwelling, historical structures, ground disturbance and potential agricultural activities.
Confluence identified six areas of environmental concern, encompassing:
Potential former orchard or cropping activities.
A suspected historical excavation area and possible imported fill.
An established access track.
The existing dwelling and detached garage.
Former structures near a farm dam.
Underground septic infrastructure.
The PSI found no evidence of gross or widespread contamination likely to prevent redevelopment. It recommended a targeted DSI to investigate the identified areas and provide a firmer basis for assessing suitability for the proposed land use.
Detailed Site Investigation
Investigating soil, surface water and sediment
Building on the PSI, Confluence undertook soil sampling at 38 locations, with surface water and sediment sampling from the property’s dams.
The program addressed the identified areas of environmental concern and included broader coverage of the investigation area. Laboratory analysis assessed contaminants relevant to the historical activities, including petroleum hydrocarbons, metals, pesticides and asbestos, with microbiological testing near the septic infrastructure.
The investigation considered both potential exposure within the development footprint and the movement of contaminants through runoff and sediment.
Interpreting findings against the proposed development
Confluence assessed the field observations and laboratory results in the context of the proposed commercial land use and updated the site’s Conceptual Site Model.
The investigation did not identify contamination requiring remediation to support the proposed redevelopment. No asbestos was detected in the soil samples submitted for asbestos analysis.
Further assessment of an isolated sediment result indicated that it did not represent a contamination constraint to the development. The findings supported suitability for the proposed commercial uses, subject to the recommended construction and hazardous materials controls.
Practical recommendations for construction
Confluence recommended a site-specific Construction Environmental Management Plan, incorporating an Unexpected Finds Protocol to address previously unidentified contamination encountered during ground disturbance.
A hazardous materials survey of existing structures was also recommended before demolition or construction works. This distinguished the findings of the soil investigation from the separate assessment required for potentially hazardous building materials.
From preliminary assessment to development advice
By delivering both the PSI and DSI, Confluence carried the assessment from historical risk identification through to intrusive investigation and a documented opinion on land-use suitability.
The two-stage approach provided the project team with a clear assessment of contamination constraints and practical requirements to carry into design and construction.
Planning a commercial redevelopment in the Hawkesbury or Greater Sydney region? Contact Confluence Environmental for preliminary and detailed site investigations.