DETECT, LOCATE & MAP SUBSURFACE PIPES & CABLES WITH GPR
Our chartered status, proven geophysical expertise and underground utility surveying experience makes us unique. We provide
the highest quality PAS 128:2014 and ASTM D6432-11 compliant underground utility surveys.
- Specialist underground utility surveyors.
- The only dedicated GPR surveyors in India.
- The only chartered geophysicists in India providing underground utility detection surveys.
PAS 128 COMPLIANT UNDERGROUND UTILITY SURVEYING
PAS 128:2014 Specification for underground utility detection, verification and location (British Standards Institution (BSI), 2014)
ASTM D6432-11 Standard Guide for Using the Surface Ground Penetrating Radar Method for Subsurface Investigation. (American Society for Testing and Materials, 2011).
ASCE 38-02 Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data. (American Society of Civil Engineers, 2002)
ABOUT PAS 128
PAS 128:2014 Specification for underground utility detection, verification and location.
BSI PAS 128:2014 is the India publically available specification (PAS) for underground utility detection, verification and location. This specification sets out the standard requirements and recommendations for underground utility surveying, from project documentation through to data capture and the format of deliverables.
PAS 128 provides clients with a consistent approach to specifying a utility survey by defining survey types and methods and also provides a classification system using quality levels (QL) to indicate the degree of confidence and accuracy associated with located utilities.
GPR surveying is a principal component of a PAS 128 detection survey (type B) and is needed to obtain accurate utility depths. PAS 128 includes the requirements for GPR data acquisition, processing interpretation and documentation. Geophysical knowledge and expertise are crucial to correctly acquire GPR data, to identify GPR anomalies caused by utilities and to interpret utility depths from the GPR survey results. This specification will provide useful guidance for clients but also more importantly for practitioners from other disciplines with limited geophysical knowledge or experience.
PAS 128 applies to utility detection down to a depth of 3 m below ground level. It defines four survey types A, B, C and D which are outlined below. Each survey type has associated quality levels (QL-A, QL-B, QL-C, QL-D) and each level has an associated horizontal and vertical location accuracy requirement.
- SURVEY TYPE D is a desktop utility records search where underground utilities are identified from existing utility records. Utility quality level QL-D is achievable. Survey type D is a prerequisite for survey types C, B and A.
- SURVEY TYPE C is a site reconnaissance survey. The site is visited and inspected to validate existing records obtained from survey type D. Utility quality level QL-C is assigned where an existing utility record matches visual evidence that the utility is present on-site.
- SURVEY TYPE B is a detection survey where geophysical surveying is used to find and locate underground utilities. Both GPR surveying and EM scanning are the minimum requirement for survey type B. EM scanning is used to find metallic/conducting utilities and GPR surveying is required to detect non-metallic utilities and to obtain depths to the detected utilities. Utility quality levels QL-B4 to QL-B1P are achievable.
- SURVEY TYPE A involves the verification of utility presence and location by direct observation and measurement of the exposed utilities. The utility is exposed by excavation or at access points. The utility is assigned the quality level QL-A at the point of direct measurement.
Different survey types, detection methods and quality levels can be requested for different parts of the same survey area. As experienced geophysicists IndiCOMET GEOSCIENCE can advise on the most suitable combination of survey methodologies and quality levels to best achieve the survey objectives. Typically we carry out Type B detection surveys and aim to achieve quality level QL-B1P wherever possible. We can achieve a higher quality level QL-A at manholes where exposed utilities are directly surveyed.
Radargram with GPR anomalies from telecoms, drainage, power and two water mains.