TERRESTRIAL AND RIPARIAN RISK HYPOTHESES
This subset of hypotheses is formulated for (1) sequential comparison to reference site or
background concentrations and (2) comparison of concentrations to media-specific
benchmarks.
Hypotheses for the riparian zone are the same as those developed for the upland zone
with the exception that the exposure media for the riparian zone include water and
bioaccumulation from water and sediment.
Hypothesis 1: Terrestrial Contaminant Assessment

Hypothesis 1a (null): Mean waste site soil contaminant concentrations of any of the
contaminants are not greater than mean concentrations in the reference site or
Hanford Site background.

Hypothesis 1a (alternate): Mean waste site soil contaminant concentrations of any of
the contaminants are greater than mean concentrations in the reference site or
Hanford Site background.
If the null hypothesis is rejected for a contaminant, then evaluate hypothesis 1b for that
contaminant. If the null hypothesis is not rejected, then consider hypothesis 1b for that
contaminant.

Hypothesis 1b (null): Mean waste site contaminant concentrations are not greater
than soil benchmarks (benchmark values were compiled for the 100-B/C Pilot Project
Risk Assessment and values for other contaminants will be compiled using the same
approach as the 100-B/C Pilot Project Risk Assessment).

Hypothesis 1b (alternate) (radionuclides): Mean waste site concentrations are greater
than soil benchmarks (benchmark values were compiled for the 100-B/C Pilot Project
Risk Assessment and values for other contaminants will be compiled using the same
approach as the 100-B/C Pilot Project Risk Assessment).
Hypothesis 2: Survival and Growth
Reference site comparison:

Null. Mean survival or growth of receptor is not less on site than in the reference
soil.

Alternate. Mean survival or growth of receptor is less on site than in the reference
soil.
Terrestrial/Riparian Hypotheses - 1
Gradient analysis:

Null. Mean survival or growth of receptor does not decrease along a gradient of
increasing contaminant concentrations.

Alternate. Mean survival or growth of receptor decreases along a gradient of
increasing contaminant concentrations.
Hypothesis 3: Species Diversity
Reference site comparison:

Null. Species diversity of receptors on site is not less than in the reference site for the
same habitat type.

Alternate. Species diversity of receptor is less on site than in the reference site for the
same habitat type.
Gradient analysis:

Null. Species diversity of receptor does not decrease along a gradient with increasing
contaminant concentrations for the same habitat type.

Alternate. Species diversity of receptor decreases along a gradient with increasing
contaminant concentrations for the same habitat type.
Hypothesis 4: Relative Population Abundance
Reference site comparison:

Null. Relative population abundance of receptor on site is not less than in the
reference site for the same habitat type (e.g., remediated and backfilled waste site).

Alternate. Relative population abundance of receptor on site is less than in the
reference site for the same habitat type.
Gradient analysis:

Null. Relative population abundance of receptor does not decrease along a gradient
with increasing contaminant concentrations for the same habitat type.

Alternate. Relative population abundance of receptor decreases along a gradient with
increasing contaminant concentrations for the same habitat type.
Terrestrial/Riparian Hypotheses - 2
Hypothesis 5: Reproductive Rates
Reference site comparison:

Null. Receptor reproductive rates are not less on site than those in the reference site
for the same habitat type.

Alternate. Receptor reproductive rates are less on site than those in the reference site
for the same habitat type.
Gradient analysis:

Null. Receptor reproductive rates do not decrease along a gradient with increasing
contaminant concentrations for the same habitat type.

Alternate. Receptor reproductive rates are less than those in the reference site or
decrease along a gradient with increasing contaminant concentrations for the same
habitat type.
Hypothesis 6: Gender Ratios
Reference site comparison:

Null. Receptor gender ratios on site do not deviate from equality in comparison to the
reference site for the same habitat type.

Alternate. Receptor gender ratios on site deviate from equality in comparison to the
reference site for the same habitat type.
Gradient analysis:

Null. Receptor gender ratios do not deviate from equality along a gradient with
increasing contaminant concentrations for the same habitat type.

Alternate. Receptor gender ratios increasingly deviate from equality along a gradient
with increasing contaminant concentrations for the same habitat type.
Hypothesis 7: Contaminant Concentrations in Biota
Reference site comparison:

Null. Mean contaminant tissue concentrations in the receptor are not greater on site
than those in the reference site.

Alternate. Mean contaminant tissue concentrations in the receptor are greater on site
than those in the reference site.
Terrestrial/Riparian Hypotheses - 3
Gradient analysis:

Null. Mean contaminant tissue concentrations in the receptor do not increase along a
gradient with increasing contaminant concentrations.

Alternate. Mean contaminant tissue concentrations in the receptor increase along a
gradient with increasing contaminant concentrations.
Comparison to no effect levels:

Null. Mean contaminant tissue concentrations in the receptor are not greater than
those associated with no adverse effects (published levels are available for only
selected contaminants such as PCBs and heavy metals [e.g., Eisler 1986, Eisler and
Belisle 1996]).

Alternate. Mean contaminant tissue concentrations in the receptor are greater than
those associated with no adverse effects (published levels are available for only
selected contaminants such as PCBs and heavy metals [e.g., Eisler 1986, Eisler and
Belisle 1996]).
Hypothesis 8: Dietary Exposure
Reference site comparison:

Null. Mean contaminant concentrations via dietary exposure to the receptor (via food
and incidental soil ingestion) on site are not greater than those in the reference site.

Alternate. Mean contaminant concentrations via dietary exposure to the receptor (via
food and incidental soil ingestion) are greater on site than those in the reference site.
Gradient analysis:

Null. Mean contaminant concentrations via dietary exposure to the receptor (via food
and incidental soil ingestion) do not increase along a gradient with increasing
contaminant concentrations.

Alternate. Mean contaminant concentrations via dietary exposure to the receptor (via
food and incidental soil ingestion) do increase along a gradient with increasing
contaminant concentrations.
Comparison to no effect levels:

Null. Mean contaminant tissue concentrations via dietary exposure to the receptor
(via food and incidental soil ingestion) are not greater than those associated with no
adverse effects (published levels are available for most contaminants).
Terrestrial/Riparian Hypotheses - 4

Alternate. Mean contaminant tissue concentrations via dietary exposure to the
receptor (via food and incidental soil ingestion) are greater than those associated with
no adverse effects (published levels are available for most contaminants).
Hypothesis 9: Juvenile Recruitment
Reference site comparison:

Null. Juvenile recruitment of receptor on site is not less than recruitment in the
reference site.

Alternate. Juvenile recruitment for receptor on site is less than recruitment in the
reference site.
Gradient analysis:

Null. Juvenile recruitment for receptor does not decrease along a gradient with
increasing contaminant concentrations.

Alternate. Juvenile recruitment for receptor decreases along a gradient with
increasing contaminant concentrations.
Terrestrial/Riparian Hypotheses - 5
NEAR-SHORE AQUATIC RISK HYPOTHESES
Hypothesis 1: Aquatic Contaminant Assessment
This subset of hypotheses is formulated for (1) sequential comparison to reference site
concentrations and (2) comparison of concentrations to no effect levels or toxicity
benchmarks:

Hypothesis 1a (null): Mean contaminant concentrations in onsite aquatic media
(porewater and sediment) are not greater than in the reference site.

Hypothesis 1a (alternate): Mean concentrations in onsite aquatic media (porewater
and sediment) are greater than in the reference site.
If the null hypothesis is rejected for a contaminant, then evaluate hypothesis 1b for that
contaminant. If the null hypothesis is not rejected for a contaminant, then consider
hypothesis 1b for that contaminant.

Hypothesis 1b (null): Mean contaminant concentrations in onsite aquatic media
(porewater and sediment) are not greater than medium-specific benchmarks
(benchmark values were compiled for the 100-B/C Pilot Project Risk Assessment and
values for other contaminants will be compiled using the same approach as the 100B/C Pilot Project Risk Assessment).

Hypothesis 1b (alternate): Mean contaminant concentrations in onsite aquatic media
(porewater and sediment) are greater than medium-specific benchmarks (benchmark
values were compiled for the 100-B/C Pilot Project Risk Assessment and values for
other contaminants will be compiled using the same approach as the 100-B/C Pilot
Project Risk Assessment).
Hypothesis 2: Survival, Reproduction, and Growth
Reference site comparison:

Null. Mean survival, reproduction, or growth of receptor on site is not less than in the
reference sites.

Alternate. Mean survival, reproduction, or growth of receptor on site is less than in
the reference sites.
Gradient analysis:

Null. Mean survival, reproduction, or growth on site does not decrease along a
gradient of increasing contaminant concentrations.
Near-Shore Aquatic Hypotheses - 1

Alternate. Mean survival, reproduction, or growth of receptor decreases along a
gradient of increasing contaminant concentrations.
Hypothesis 3: Species Diversity
Reference site comparison:

Null. Species diversity of receptor is not less on site than diversity in the reference
sites for the same habitat type (substrate).

Alternate. Species diversity of receptor is less on site than diversity in the reference
sites for the same habitat type (substrate).
Gradient analysis:

Null. Species diversity of receptor does not decrease along a gradient with increasing
contaminant concentrations for the same habitat type (substrate).

Alternate. Species diversity of receptor decreases along a gradient with increasing
contaminant concentrations for the same habitat type (substrate).
Hypothesis 4: Relative Population Abundance
Reference site comparison:

Null. Relative population abundance of receptor on site is not less than abundance in
the reference sites for the same habitat type (substrate).

Alternate. Relative population abundance of receptor on site is less than abundance
in the reference sites for the same habitat type (substrate).
Gradient analysis:

Null. Relative population abundance of receptor does not decrease along a gradient
with increasing contaminant concentrations for the same habitat type (substrate).

Alternate. Relative population abundance of receptor decreases along a gradient with
increasing COPEC concentrations for the same habitat type (substrate).
Hypothesis 5: Contaminant Concentrations in Biota
Reference site comparison:

Null. Mean contaminant concentrations in receptor tissue on site are not greater than
those in the reference sites.
Near-Shore Aquatic Hypotheses - 2

Alternate. Mean contaminant concentrations in the receptor tissue on site are greater
than those in the reference sites.
Gradient analysis:

Null. Mean contaminant concentrations in receptor tissue on site do not increase
along a gradient with increasing contaminant concentrations.

Alternate. Mean contaminant concentrations in the receptor tissue on site increase
along a gradient with increasing contaminant concentrations.
Comparison to no effect levels:

Null. Mean contaminant tissue concentrations in the receptor are not greater than
those associated with no adverse effects (published levels are available for only
selected contaminants such as PCBs and heavy metals [e.g., Eisler 1986, Eisler and
Belisle 1996]).

Alternate. Mean contaminant tissue concentrations in the receptor are greater than
those associated with no adverse effects (published levels are available for only
selected contaminants such as PCBs and heavy metals [e.g., Eisler 1986, Eisler and
Belisle 1996]).
Hypothesis 6: Dietary Exposure
Reference site comparison:

Null. Mean contaminant exposure concentrations (via food, water, and incidental
sediment ingestion) are not greater than those in the reference sites.

Alternate. Mean contaminant exposure concentrations (via food, water, and
incidental sediment ingestion) are greater than those in the reference sites.
Gradient analysis:

Null. Mean contaminant exposure concentrations (via food, water, and incidental
sediment ingestion) do not increase along a gradient with increasing contaminant
concentrations.

Alternate. Mean contaminant exposure concentrations (via food, water, and
incidental sediment ingestion) increase along a gradient with increasing contaminant
concentrations.
Comparison to no effect levels:
Near-Shore Aquatic Hypotheses - 3

Null. Mean contaminant exposure concentrations (via food, water and incidental
sediment ingestion) are not greater than those associated with no adverse effects
(published levels are available for most contaminants).

Alternate. Mean contaminant exposure concentrations (via food, water and incidental
sediment ingestion) are greater than those associated with no adverse effects
(published levels are available for most contaminants).
Near-Shore Aquatic Hypotheses - 4