For areas of unknown UXO contamination, following archive research, a wide area assessment should be considered as the first step.  NOTRA was contracted by Defence Construction Canada to conduct wide area assessments in portions of the Ottawa River adjacent to CFB Petawawa and at CFB Borden, Area E.

For both sites (160 Ha and 220 Ha), a Geonics EM-61 was used to collect data at a survey resolution of 10%.  Following interpretation and statistical analysis it was possible to generate anomaly density maps for a range of anomaly parameters (depth/amplitude/estimated size). 

For CFB Borden, Area E, there are clearly some high density zones while there are vast parts of the over 220 Ha site that have a low density of anomalies.

For the Ottawa River example, follow-up to the wide area assessment included the 100% clearance of 20 20m x 20m calibration grids.  Calibration Grid 9 is included with the figure of a portion of the wide area assessment area.  The results of the calibration grid survey, in conjunction with the wide area assessment provided a basis for estimating the number of UXO items as well as the total number of anomalies present in the area. 

These results were also used to omit a portion of the area as low anomaly densities were identified and no munitions related items were identified in the calibration grids.

The data collected in wide area assessment surveys can easily be used to build a GIS model of a site, and assist in land use assessments.  This data can also easily be used in more advanced statistical modeling such as Visual Sample Plan.

Back