Navigating Construction Without Topographical Survey and Geotechnical Investigation

Initiating construction projects without the necessary topographical survey and geotechnical investigation can be daunting. Despite the presence of government-issued topographic maps, the availability of these critical resources is often insufficient. This article aims to provide a comprehensive guide on how to proceed and what to consider when these essential documents are not available.

The Importance of Topographical Survey and Geotechnical Investigation

Every state's agricultural report, such as in New Jersey, provides valuable insights into the drainage properties, topographical features like swamps, hills, and meadows, and historical land use. However, these reports may be outdated or lack detailed information relevant to modern construction projects. For instance, my experience living in a house reveals that the area, once a golf course, had undulations in the fill that compressed unpredictably, leading to varying ground conditions. This underscores the importance of obtaining the most up-to-date and accurate information.

The Role of Initial Feasibility Studies

Before commencing any construction project, it is essential to conduct initial feasibility studies. These studies should include a thorough understanding of the area's topography and subsurface conditions. The absence of critical information can lead to significant uncertainties, which may impact the project's feasibility and success. It is crucial to recognize that the success of your construction project depends on accurate and reliable data.

Conducting Your Own Investigation

When you do not have access to comprehensive topographical survey and geotechnical reports, your first step should be to conduct your own investigation. This may involve the following steps:

Consult neighboring properties for any available information on construction history and topographical features. Review geological maps to identify potential risks and opportunities. Examine local maps, which can provide valuable insights into topography and previous land use. Access local records and archives at libraries or municipal offices to gather historical data.

For example, a historical check revealed that a site had been used for extracting soft clay for pottery. Subsequent infilling was undocumented and insufficient for building. The car park and turning areas on the site undulated due to the random compression of the fill. Additionally, various toxic materials could be present, including hazardous chemicals and old asbestos.

Understanding the Impact of Variations

Without accurate topographical and soil information, your construction estimates are based on assumptions that may prove unrealistic. It is crucial to state your expectations or assumptions and the potential impact of variances from them. Clients must be made aware of the uncertainties and the potential risks associated with unconventional ground conditions.

Costing and Quotations

Construction quotes should reflect real knowledge, facts, and agreed conditions. While some contractors may offer quotations for any ground conditions, they must clearly outline the risks and costs associated with building over disused quarries, old mineshafts, poor infill, and other potential environmental issues.

Example: If you are asked to quote for a construction project without a topographical survey and geotechnical investigation, be prepared to address the following:

Expectations and assumptions regarding the site's geology. The potential costs associated with excavation, filling, and ground strengthening. The need to account for potential environmental hazards and the associated mitigation measures. Qualifiers and conditions that must be met for the project to proceed safely and within budget.

In conclusion, initiating a construction project without proper topographical survey and geotechnical investigation requires careful planning and thorough investigation. By taking a proactive approach to gathering information and understanding the potential risks, you can ensure a more accurate and successful project outcome.