Non-destructive technology for underground utility mapping: A case study

This article presents a case study of underground utility mapping survey carried out for a proposed Bridge site in Ahmedabad, Gujarat. The main focus was on mapping possible underground metallic as well as non- metallic utilities, viz, water line, sewer line, gas pipeline, cables etc. using Ground Penetrating Radar (GPR). With the growing needs and ever pinching demand for progressive infrastructure, the pre-existing infrastructure needs to be preserved. GPR is one such tool that can be used for non-destructive survey for utility mapping, concrete inspection, road inspection, archaeology, environmental assessment and many more. An area of around 15000 m² is scanned over the bitumen road surface of stretch 700 m length and 22 m width. A GSSI GPR system SIR-3000 was used equipped with 400 MHz ground coupled antenna to cover the depth of penetration up to 3 m. The data was collected at spacing of 6 m across the road where as 2.5 m along the road to map possible utilities in both the directions. In comparison to traditional methods of excavation and trenching which involve a huge loss in terms of time, money and man power GPR can prove to be cost efficient, less invasive and more reliable. GPR survey is expected to be a more efficient technique for underground survey especially in infrastructure projects which involve huge quantum of money in excavation and filling and where cost cutting is a must.