The importance of soil investigation as a risk management tool and guarantee of infrastructure sustainability cannot be over-emphasized. A typical soil investigation programme entails the collection of sub-surface (soil, water and rock) samples for testing on-site or in a specialised laboratory for specific pre-determined parameters, or in-situ (“on the spot”) collection of data (geotechnical engineering parameters) for site characterisation. After which either a Factual Geotechnical Report addressing the sampling programme, laboratory analysis, borehole logs and a profile of the subsurface conditions; or an Interpretative Report (interpreting the geotechnical engineering properties, determining the soil bearing capacity and identifying the need for any possible ground improvement) is produced.
In coming up with budgets for performing soil investigations, construction and infrastructure development firms need to consider a series of factors including but not limited to:
- Personnel categories
Personnel man-hour costs include day rates (for the expected duration for completing the volume of insitu-testing, drilling & sampling, laboratory analysis and reporting) for Experts – Geotechnical Engineers/Geologists, Skilled labour – Drillers/Operators/Technicians/Assistants and Semi/un-skilled labour – Field assistants and labourers.
This involves the costs of equipment to be deployed and used for the soil investigation. Equipment ranges from heavy equipment including rotary rigs, cable & percussion rigs and cone penetration test rigs, to more portable equipment – Dynamic Cone Penetrometers, Dynamic Probes and on-shelf laboratory testing equipment.
- Site Condition
The site condition determines accessibility and the type of equipment to be deployed. Also, onshore and nearshore/over-water locations require different suites of equipment; an onshore location maybe on solid ground or swampy location while a nearshore/over-water location requires a work platform (pontoon, jack-up barge, cantilever structure as well as support vessel). All of these determine the costs requirement.
- Community relations and Security
Community relations and Security costs are necessary to guarantee the smooth operation of soil investigation programmes and safety of personnel and equipment involved. This can be achieved through appropriate and adequate consultation with relevant stakeholders; by paying homage to the community chiefs/elders and representatives as may be required, communicating the scope/extent of the soil investigation work in the area/community, and offering temporary employment through engagement of local labour/field assistants.
- Investigation Requirement
- Depending on the infrastructural needs and level/detail of information required, the project cost rises proportionately; preliminary investigation budget is considerably lower than a detailed investigation with expanded scope of work/specialised testing.
- Cost of laboratory testing depends on the level/requirement of testing. Tests varies from simple to specialised, single stage to multiple stages, short to long duration, and more importantly, in accordance to relevant/specified standards.
- Cost for providing factual report and/or interpretative (with recommendations) report also varies.
- Cost of Fund
- Where safeguards are required to guarantee delivery of a project, for example; Advance Payment Guarantee and Performance Bond, consideration should be given for the cost of acquiring such guarantees from the bank. Banks charge a percentage of the total project cost and also lock up the advance payment for a certain period as the case maybe. Hence the Data Collection Company may be required to allocate its money that could have been invested, to fund the soil investigation programme.
- Other applicable costs to be considered include costs of acquiring regulatory permits, medical evacuation costs in terms of emergency, inspection of equipment, calibration of equipment, induction, etc.
With consideration to the minimum factors listed above, a firm is able to estimate the cost for performing soil investigations so as to manage the risks involved and guarantee the sustainability of the related infrastructure.