&EPA
United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
DIRECTIVE NUMBER: 9481-08(84)
TITLE: ACL Demonstrations/ Risk Level, and Subsurface
Environment
APPROVAL DATE: 7-19-84
EFFECTIVE DATE: 7-i*-84
ORIGINATING OFFICE: office of Solld Waste
D FINAL
D DRAFT
STATUS:
I I
f ]
A- Pending OMB approval
B- Pending AA-OSWER approval
I ] C- For review &/or comment
[ ] D- In development or circulating
REFERENCE (other documents): headquarters
OSWER OSWER OSWER
VE DIRECTIVE DIRECTIVE Dl
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4 9 (984
^xrt»rnatTon»l Pap«r ACL Demonstration
Randall W, Breeden, Hydrologist
Land Disposal Branch (WH-565E)
Bob Stewart/ Environmental Engineer
Hazardous Materials Branch, Region VII
The meeting with International Paper on June 21, 1984, answered
some of our questions concerning the latest resubmittal of IP's
ACL demonstration (May 1, 1984). IP answered the questions of
whether or not the proposed AEL values would become IP's proposed
ACL values and, will all ACLs be calculated using a 10~5 risk
level to protect human health and the environment. IP stipulated
that the calculated AEL values would become their proposed ACL
value at the point of compliance, and that a 10~5 risk level
will be used to calculated the ACL values.
We informed IP that the methodology used to calculate
the AEL values was reasonable and adequate. We also provided
thea with a copy of Dr. Michael Dour son's memo .and comments.
Two important decisions have since been made by senior
management pertaining to the ACL issue as a result of this demon-
stration. The first concerns the acceptable level of risk that
the Agency will adopt as adequately protecting human health.
The second deals with IP's proposal to use ACL values that are
based on a 10~5 risk to human health and the environment. On
June 6, 1984, Lee Thomas signed the Record of Decision for the
Reilly Tar Pits Site (CERCLA) establishing the level of risk
that the Agency accepts as being protective of human health.
That risk level was 10~6. Therefore the 10~6 risk level is policy
for future ACL demonstrations where risks to human health
are calculated.
There is another problem with IP's proposed ACL"
demonstration. Due to the nature of the suDsurface environment
at the IP facility, specifically the mine shafts and vents,
groundwater flow beyond the facility boundary via
the horizontal nine shafts is probable. Hence, retardation
and attenuation mechanisms that could act to decrease the
concentration of a hazardous constituent along the flow path
from the point of compliance to a point of use will not occur in
the subsurface channels. Therefore, in order for IP to justify
the proposed ACL values they must adequately demonstrate
to the Agency that there will be an order of magnitude decrease
in concentration of hazardous constituents in the horizontal mine
shafts from the point of compliance to the property boundary.
If IP can successfully and adequately demonstrate this, then the
proposed ACL values will be based on a 10"6 risk level and a
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factor of 10 reduction of concentration in the »ine shaft*. It
should be noted that these ACL values for hazardous constituents
will be equivilent to IP's proposed 10~5 risk level values-.
with no redeuction in concentration occuring.
WU-565E:RBreeden:ap:382-4658:rm2102:WSM:7/19/84
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