Lesson 3/Learning Event 2
LEARNING EVENT 2:
PREPARE A CHEMICAL SURVEY OVERLAY
In order to prepare a chemical survey overlay, you must select the survey route, select critical points for
immediate reporting, and determine the amount of detail to be included in the survey. The amount of
detail will depend upon an evaluation of known contamination, time available, size of the area to be
surveyed, and number of teams available for the survey. Critical points for immediate reporting will be
selected based on operational requirements. For example, a critical water source would be a point for
immediate reporting if a decontamination operation is being planned.
Selection of the route to be followed will be based on the same factors as outlined in Lesson 2, Learning
Event 6. In summary, factors to consider are:
Location of suspected contamination.
Size and type of unit which will use the area.
Availability of cover and concealment.
Likely terrain features where chemical agents would collect, such as ravines, and locations
such as shell craters.
Suspected enemy locations and fields of fire.
Movement from one easily identified point to another.
If additional information is needed for planning the mute, it can be obtained from aerial photographs
when they are available.
The steps in preparing a chemical survey overlay are similar to those for preparing a ground radiological
survey overlay. Check points are plotted in the same manner and any other known features not on the
map are plotted on the overlay.
Figure 28 on page 100 is an example of a chemical hazard prediction and chemical survey overlay with
selected points circled and numbered. The overlay was prepared after receiving reports of suspected
contamination along the supply routes and an NBC 1 (Chemical) Report of an artillery attack employing
nerve agents at a location west of Cozy Valley, at co-ordinates EG149879.