KIRTLAND AIR FORCE BASE ALBUQUERQUE, NEW MEXICO ...

APPENDIX A
Determination of media that could be affected in the future by downgradient or offsite
contaminant migration
If the site conceptual model lacks any information necessary to accurately define site contamination,
statistical procedures will be used to determine sample locations and frequency. Guidance used to
develop statistical sampling plans will come from the following documents:
Preparation of Soil Sampling Protocols: Sampling Techniques and Strategies (EPA, 1992)
Statistical Methods for Environmental Pollution Monitoring (Gilbert, 1987)
3.1.1 Determination of Sample Frequency
It is important when, evaluating analytical data using statistics, to have a number of measurements to
generate meaningful and defensible results. Thus, the frequency of samples collected during a field
program must support the program Data Quality Objectives (DQOs) for precision and accuracy.
Methods prescribed by EPA (1992) and Gilbert (1987) can be used to determine an adequate population
size such that an estimated mean of the population achieves a prespecified accuracy with respect to
program DQOs. These methods assume that data are uncorrelated over any period of time or where the
distance between data points is sufficiently large and data are normally distributed. All of these methods
specify at least one statistical variable that is either estimated based on pre-existing data or data from an
area geochemically similar to the study area, or is estimated based on professional judgment. It is
preferable to use pre-existing or similar data if they are available.
3.1.2 Determination of Sample Locations
Sample locations can be determined for sites where there is a lack of information in the site conceptual
model. If source areas or the extent of contamination within a site are not known, statistical techniques
will be used to determine sample locations. Statistical calculations for these sample location
determination methods are expressed as functions of probability and the size of the site. These two
factors will be taken into account when evaluating and implementing the appropriate statistically-based
sampling approach. These statistical sampling approaches include:
Simple random sampling—This approach is appropriate where there is inadequate
information on the possible nature and extent of contamination to develop a site conceptual
model.
Stratified random sampling—This approach takes into account environmental factors and
contaminant physical characteristics to increase data precision while controlling sources of
variation. This sampling technique takes into account the lateral and vertical
nonhomogeneity of the environmental media of interest.
Systematic sampling—This approach attempts to provide a better coverage from samples
collected in a regular pattern, such as a grid. Where geostatistical techniques will be used to
interpret data, systematic sampling is strongly recommended.
Search sampling—This approach determines sampling of contaminant point sources („hot
spots‟) within a site. The size of the point source and the size of the study area are taken into
account to define a grid spacing that will sample the „hot spot‟ based on a specified
Kirtland AFB
Field Sampling Plan A-16 April 2004