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Reputable geotechnical engineering solutions in NSW
We provide clients with a range of comprehensive services, including:
- Geotechnical site investigations
- Geotechnical engineering report
- Engineering geology
- Foundation engineering
- Dam engineering, embankment design & specification
- Instrumentation and monitoring
- Slope instability and risk assessments
- Footing certifications
- Supervision and certification of earthworks and controlled fill, including Level 1 and Level 2 supervision
- Excavated soil/rock assessments
- VENM and waste classification assessments
- Pavement engineering and design (inc. vibration monitoring)
- Point load (UCS testing)
- Effluent disposal (wastewater) assessments to AS1547
- Soil electrical resistivity testing
- Ground vibration monitoring
Site Classification Reports
Site Classification reports are used by structural engineers to accurately determine the most appropriate footing and slab design for a proposed residential development, in order to withstand the expected ground movement on a particular site. Site classification reports are also typically required to be submitted to council as part of the development approvals process.
For Site Classifications Fortify Geotechnical Engineers investigate subsurface conditions of the site by using one or two boreholes drilled to about 1.5m depth as well as a dynamic cone penetrometer (DCP) test if required. Subsurface conditions are visually logged by an experienced geotechnical engineer, and the hole immediately backfilled upon completion. The holes would be drilled at/near the location of the proposed development depending on access and location of underground services (Telstra, power, gas, water, sewer, etc.). More often than not, the fieldwork can be done within about a week of approval, allowing for underground services clearances, and our report would be issued soon thereafter.
Following sitework, Fortify Geotech provides a copy of the report, which would include:
- Engineering logs of the boreholes & plan showing borehole & DCP locations
- Description of the site geology/subsurface conditions including existing fill, bedrock and groundwater
- Site classification to AS2870 and potential soil reactivity
- Recommend building footing types, founding strata and allowable bearing pressures
- Any other relevant geotechnical information, including excavation conditions (if a site cut is required), suitability of excavated material for use in controlled fill platforms and advise for construction of building platforms, stability of cut batters etc.
- Advise on site drainage
Fortify Geotech conducts site classifications all over NSW however for standard residential developments, within the red circle below, our estimate of fees and costs to carry out the investigation is $1,100 + GST. For site classifications with basements, pools or properties that lie outside this area, please feel free to give us a call or send us an enquiry through the contact page.
Geotechnical Site Investigations
Geotechnical investigations involve drilling and visually logging boreholes in accordance with the Unified Soil Classification System (USCS). Investigations may also involve SPT testing, soil sampling for Californian bearing ratio (CBR) and acid suphate soils as well as dynamic cone penetrometer tests (DCP).
The outcome of our Geotechnical Investigations is a model of the subsurface profile of the site. This information allows us to:
- Verify depths and strengths of bedrock (if any) for basement construction and design Recommend building footing types, founding strata and allowable bearing pressures
- Provide advice on preparation of subgrades for building slabs, vehicle pavements and carpark
- Advise on excavation conditions, suitability of excavated material for use in controlled fill platforms and advise for construction of building platforms
- Confirm stability of cut, batters, and shoring/support of temporary basement excavations
- Provide design parameters for temporary excavation support
- Confirm earth/rock pressure parameter values for retaining wall design
- Advise on Indicative subgrade design CBR for carpark subgrades
- Provide earthquake design parameters to AS1170.4 – 2007, as well as;
- Advise on site drainage
Slope Stability and Risk Assessments
Slope stability assessments are usually conducted in landslip prone areas where the gradient of the site is greater than 18°. Many councils in NSW require residential and commercial properties to have a slope stability and risk assessment conducted by an experienced geotechnical engineer for Development Approval (DA).
Slope stability and Risk assessments involve a preliminary desktop and historical data study prior to attending the site. When on site, our experienced geotechnical engineer will ascertain a geological model and a subsurface profile by mapping the geological and geomorphological features of the site, as well as conducting an intrusive investigation which would include drilling and visually logging boreholes in accordance with the Unified Soil Classification System (USCS). Dynamic cone penetrometer tests (DCP) are also conducted when necessary. The site data is then used to carry out a risk assessment using the Australian Geomechanics Society (AGS) Guidelines.
Supervision and Certification of Earthworks and Controlled Fill
Level One Supervision has become a standard requirement for many building development sites. With Fortify Geotech, Level One supervision ensures an earthworks site has been filled and compacted to a high standard under controlled conditions.
A Fortify Geotech engineer will oversee and supervise the earthworks including:
- The removal of all non-certified fill, topsoil and deleterious material
- The placement and compaction of fill
- Proof rolling the foundations to check for any weak or wet areas that would require replacement.
- Confirmation of the suitability of the foundation.
- Trenching and backfilling
- Proof rolling and testing
On completion of the supervised earthworks, the geotechnical engineer will provide a report containing the test results and test locations, the details of the inspections and a controlled fill certification.
Fortify Geotech has extensive geological knowledge of the Sydney and New South Wales area. The geotechnical engineers at Fortify Geotech are supported in fieldwork and technical work by senior engineering geologist Dennis Dyer. Dennis provides specialised geological expertise for both small and major project needs. Dennis has 50 years experience in engineering geology, including work on the dams and tunnels of the Snowy Mountains Scheme, and tertiary lecturing.
As a small consultancy, we do not require external QA accreditation however we are fully conversant with all current QA guidelines. Likewise, when working with clients, we fully comply with the obligations of their individual QA systems.
To monitor all processes and maintain our high standards of delivery, we ensure:
- Investigations are conducted in accordance with Australian standards.
- All work is cross checked, with reports reviewed prior to issue to clients.
- Records are kept in a central filing system for easy reference.
- Streamlined procedures for processing all commissions, from proposal through to issue of reports.
All accreditations held by Fortify Geotech are available on request.