Frequently Asked Questions

Find the answers below to some frequently asked questions about JK Group. If you can’t find the answer to your specific question, please contact us for more information.

Why is it necessary to carry out geotechnical investigations?

Geotechnical reports provide advice that can assist in identifying issues or constraints early on in the development of a project which could otherwise cause costly design changes and/or delays to projects if not carried out.

Investigations are undertaken to obtain information on subsurface conditions, to provide comments and recommendations on the geotechnical aspects of the design of proposed buildings or structures. Geotechnical aspects include: excavation conditions, site stability, groundwater levels, footing design, retaining walls and many more.

Some local Councils, such as Pittwater and Woollahra councils, require geotechnical reports to accompany Development Applications (DAs).

Why is it necessary to carry out an environmental investigation?

Environmental investigations are undertaken to identify, assess and minimise potential risks to human safety and/or nature from a proposed development.

Investigations are often required to satisfy legislative regulations, for instance under the Environmental Protection Authority guidelines waste classification of site materials are often required, along with specialised disposal of some types of excavation spoils. If waste classifications are not carried out before commencement of a project, it can cause significant delays to a project with potentially very large construction cost variations.

Many local councils also require environmental investigations for developments where potential acid sulfate soils or soil salinity may be an issue and where hazardous materials, such as asbestos and lead paint, could be present in old buildings.

What should a site investigation report provide?

As a general rule, a site investigation report should:

  • Describe the investigative procedures
  • Present field and laboratory test data
  • Provide interpretive comments on the data as appropriate, e.g. Groundwater is at 3m, but is probably a ‘perched’ water table
  • Review results against other relevant data and, for environmental work, statutory or other stipulated guidelines
  • Review proposed construction or development issues and the influence of the subsurface conditions
  • Suggest appropriate parameters for design, and/or suggest and assess remediation proposals for the site (environmental only)
  • Discuss potential design and construction solutions and risks on the basis of ‘if you do this, this could happen’
  • Detail the need for further investigation or any accessory construction stage inspections required to verify assumptions made at the design stage.

Most methods of investigation generally only indicate subsurface conditions at the specific locations where the tests or samples were taken. They cannot necessarily be relied upon to accurately reflect strata variations that may exist between test or sample locations.

What should a site investigation report provide?

How do I decide the extent of investigation required?

Deciding the extent of an investigation is a balance between uncertainties associated with anticipated conditions and the economic effects of these uncertainties on overall project costs. There are diminishing returns but generally the more detailed the scope of the investigation, the less risk of economic surprises later on in the project.

What type of investigations are there?

Investigation is generally an iterative procedure in which fieldwork is carried out to fill gaps in existing knowledge of a site. The types of investigation are broadly:

  • Desk study
  • Site assessment
  • Preliminary site investigation
  • Comprehensive site investigation
  • Supplementary site investigation
  • Field trial
  • Monitoring of construction

For many projects, the cost effective solution for investigation is a single, comprehensive investigation that will also include the desk study and site assessment components. Most projects where a comprehensive investigation is completed will then just require site inspections during construction to verify the assumptions made on the continuity and quality of the strata.

How much does a geotechnical or environmental investigation cost?

For most investigation and assessment projects we can provide a lump sum fee that includes fieldwork, testing and a report.

If clients or their representatives are confident and experienced they may nominate a scope of work, but in the majority of cases, we suggest a scope which they consider balances the need for adequate information against the incremental cost benefit of increasing scopes of work.

In more complex cases and legal work where the scope cannot be defined, our fees are based on competitive hourly rates. Our experienced professionals are always available to take enquiries and provide advice clients may require about how to proceed.