Final Second Five-Year Review Report Fort Ord Superfund Site ...

from consideration for potential remediation, and (3) identify sites that require additional investigation, or
should be considered for remediation. The Basewide Range Assessment process involved five steps:
1) review of historical documents including historical training maps, historical aerial photographs, range
control records, and military munitions after action removal reports, 2) site reconnaissance and mapping,
3) limited soil sampling for screening purposes, 4) site characterization, and 5) remediation/habitat
mapping.
This investigation identified areas of additional soil contamination associated with ranges within Site 39
and resulted in a significant increase in the volume of soil to be excavated at the site.
Ecological Risk Assessment
The ERA for Small Arms Ranges, Habitat Areas, Impact Area, Former Fort Ord, California
(MACTEC and Arcadis/BBL, 2007) described the methods, approach, and results of an assessment
conducted to evaluate potential ecological risks for the ranges within habitat areas of the Impact Area.
The ERA is being used to guide risk management decision-making. The overall approach for conducting
the ERA was to evaluate potential ecological risk under a baseline scenario (i.e., current conditions with
no remediation) and evaluate risk reduction based on various potential remediation scenarios developed
based on an assessment of habitat quality and distribution and concentrations of contaminants.
The ERA focused on chemical contamination in soil associated with 22 Range Areas at Site 39; lead,
copper, antimony and explosive compounds were identified as chemicals of potential ecological concern.
Ecological receptors at the Impact Area evaluated in the ERA included plants, reptiles,
herbivorous/insectivorous mammals, omnivorous/carnivorous mammals, herbivorous birds,
carnivorous/omnivorous birds, and insectivorous birds. Aquatic receptors were also evaluated for pond
areas.
Because previous ecological risk evaluations for the Impact Area were conducted using limited soil and
biota data, an ERA sampling program was conducted to fill data gaps for the evaluation of ecological
risks. A total of 40 locations within the ranges were sampled, and lead bioavailability tests were also
conducted on soil and plant samples. Baseline (NoA) risks were estimated for the receptors and exposure
areas, and risk estimates were then calculated for a range of remedial exposure scenarios to evaluate both
the level of risk reduction gained and amount of habitat destroyed under various potential remediation
scenarios. The primary goal of developing the remedial risk scenarios was to devise a remediation
approach which maximizes risk reduction within known and potential breeding habitat for the California
Tiger Salamander (CTS) along with preservation of high-quality habitat to be used in remedial decisionmaking.
Feasibility Study Addendum
The FS Addendum (Shaw, 2007) for the Site 39 Ranges presents the revised SRUs originally identified
in the Basewide RI Sites ROD for Site 39 based on additional investigations for contaminated soils and
the ERA completed at Site 39 since the time the ROD was prepared. The purpose of this FS Addendum
is to summarize the results of the comprehensive Basewide Range Assessment and ERA for contaminated
soils present at Site 39, and identify the revised remedial units based on those results for which the
original preferred remedial alternative of Onsite Placement at the OU2 Landfill Beneath a Cap will be
implemented as identified in the Basewide RI Sites ROD. The results of the Basewide Range Assessment,
ERA, and this FS Addendum will be used to guide risk management and remedial decision-making for
these ranges during the preparation of a ROD amendment to address ecological risks and the additional
volume of contaminated soil which will require remediation.
Final
7-12
FORMER FT ORD 5YR REVIEW 2007_FINAL United States Department of the Army