focus additional sampling on areas of known con-
contributes much more to total error than analyti-
tamination, thus possibly saving additional mo-
cal variability (EPA 1990, 1992a). Under these con-
bilization and sampling efforts. This approach has
ditions, the major effort should be to reduce sam-
been successfully used for a Superfund remedial
pling variability by taking more samples using less
investigation of an OB/OD site (Craig et al. 1993).
expensive methods (EPA 1992a).
During site remediation, such as Superfund re-
EPA's Guidance for Data Useability in Risk As-
medial actions, data are needed on a near-real-time
sessment (EPA 1992a) indicates that on-site meth-
basis to assess the progress of cleanup. On-site
ods can produce legally defensible data if appro-
methods can be used during remediation to guide
priate method quality control is available and if
excavation and materials handling activities and
documentation is adequate. Field analyses can be
to evaluate the need for treatment on incremental
used to decrease cost and turnaround time as long
quantities of soil (EPA 1992b). Final attainment of
as supplemental data are available from an ana-
soil cleanup levels should be determined by an
lytical method capable of quantifying multiple
approved laboratory method, such as EPA Method
explosives analytes (e.g., Method 8330) (EPA
8330. This approach was effectively used at a
1992a). Significant quality assurance oversight of
Superfund remedial action for an explosives wash-
field analysis is recommended to enable the data
out lagoon (Oresik et al. 1994, Markos et al. 1995).
to be widely used. The accuracy (correctness of
the concentration value and a combination of both
systematic error [bias] and random error [preci-
sion]) of on-site measurements may not be as high
DATA QUALITY OBJECTIVES
in the field as in fixed laboratories, but the quicker
The EPA Data Quality Objectives process is
turnaround and the possibility of analyzing a
designed to facilitate the planning of environmen-
larger number of samples more than compensates
tal data collection activities by specifying the in-
for this factor. Remedial project managers, in con-
tended use of the data (what decision is to be
sultation with chemists and quality assurance per-
made), the decision criteria (action level), and the
sonnel, should set accuracy levels for each method
tolerable error rates (EPA 1994, ASTM 1996). Inte-
and proficiency standards for the on-site analyst.
grated use of on-site and laboratory methods for
On-site methods may be useful for analysis of
explosives in soil helps to achieve such objectives
waste treatment residues, such as incineration ash,
as determining the horizontal and vertical extent
compost, and bioslurry reactor sludges. However,
of contamination, obtaining data to conduct a risk
on-site methods should be evaluated against labo-
assessment, identifying candidate wastes for treat-
ratory methods on a site- and matrix-specific ba-
ability studies, identifying the volume of soil to
sis because of the possibility of matrix interference.
be remediated, determining whether soil presents
Treatability studies are used to evaluate the po-
a potential detonation hazard (reactive according
tential of different treatment technologies to de-
to RCRA regulations), and determining whether
grade target and intermediate compounds and to
remediation activities have met the cleanup
evaluate whether cleanup levels may be achieved
criteria.
for site remediation. Treatability study waste for
Environmental data such as rates of occurrence,
explosives-contaminated soils should be of higher-
average concentrations, and coefficients of varia-
than-average concentration to evaluate the effects
tion are typically highly variable for contaminants
of heterogeneous concentrations and the poten-
associated with explosives sites. These differences
tial toxicity effects for processes such as
are a function of fate and transport properties,
bioremediation.
occurrence in different media, and interactions
During remediation of soils contaminated with
with other chemicals, in addition to use and dis-
explosives, it is necessary to monitor the rate of
posal practices. Information on frequency of oc-
degradation and determine when treatment crite-
currence and coefficient of variation determines
ria have been met so that residues below cleanup
the number of samples required to adequately
levels can be disposed of and additional soil
characterize exposure pathways and is essential
treated. Soils contaminated with explosives are
when designing sampling plans. Low frequencies
currently being treated by incineration,
of occurrence and high coefficients of variation,
composting, and solidification/stabilization
such as with explosives, mean that more samples
(Noland et al. 1984, Turkeltaub et al. 1989, EPA
will be required to characterize the exposure path-
1993, Craig and Sisk 1994, Miller and Anderson
ways of interest. Sampling variability typically
1995, Channell et al. 1996). Other biological treat-
4
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