FINAL SAMPLING AND ANALYSIS PLAN - Documents for Moffett Field

Worksheets 11, 14, 15, 17
Worksheets 11, 14, 15, 17
locations were selected randomly
and edit the sampling approach to
include analyzing all samples at
once instead of a step-out approach.
The soil decision units is (are) not
clearly defined. Step 5 of Table 11-
1 states that the contaminated soil at
the area where exceedance was
detected will be removed. However,
the boundaries of the area that
would be removed are not indicated
in the SAP. Revise the SAP to
define the decision units for the
potential soil excavation areas.
Please eliminate the references to
the 95% confidence levels for
confirming the removal action has
not impacted soil. The comparison
between baseline and post- removal
levels should be conducted on a
point by point basis with regulatory
consultation. The 95% confidence
interval approach may average over
too large of an area to be able to
The Pre-Final Draft will define the
soil decision units and boundaries
of excavation areas. A grid
approach will be adopted for
baseline and confirmation
sampling. In general, if an
exceedance occurs at any sample
location, the soil will be excavated
half way to the next clean location,
in each direction. Confirmation
samples will then be collected
from the bottom of the excavation,
at the center and on all four sides
of the excavation. Sample results
will be provided to both EPA and
Water Board for consultation on
the specific soil removal approach.
Text references to the 95% will be
removed. The comparison between
baseline and post- removal levels
will be conducted on a point by
point basis in consultation with
EPA and the Water Board.
Response to Comments on Draft Sampling and Analysis Plan
Moffett Field, California
DCN: AMEC-8816-0005-0040
April 2010
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