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8.0 POSTCLOSURE
DOEIRL-90-11, Rev. 2
05/99
2 This closure plan proposes clean or modified closure of the 300 Area WATS in two steps occurring over
3 an extended closure period. The first step will be partial clean closure of portions of the TSD under this
4 closure plan. The second step will be final closure to occur at a later date (Chapter 6.0). As described in
5 Chapter 7.0, Section 7.6, during the period between partial and final closure, an annual inspection and
6 maintenance, if required, will occur, which does not equate to postclosure care.
8 Postclosure care would be required if the unit cannot be clean closed at the time of final closure. Under
9 these conditions, alternative RCRA unit closure methods are landfill closure and modified closure.
10 Landfill closure will not be considered here because, as with the adjacent 300-FF-1 [source] OU, the
11 300-FF-2 CERCLA [source] OU ROD is anticipated to require cleanup to industrial levels that will, at a
12 minimum, qualify the unit for modified closure. Modified closure could occur if RCRA unit dangerous
13 waste constituents in soil exceed the clean closure performance standards of WAC 173-303-610 (2)(b)(i)
14 but do not exceed MTCA, WAC 173-340-745, Method C cleanup levels. Modified closure (if necessary)
15 would not occur until a determination was made that soil contamination would not be remediated under
16 the CERCLA 300-FF-2 OU cleanup action to RCRA clean closure standards. Modified closure would
17 occur under the conditions of the Hanford Facility RCRA Permit, Section II.K.D. Postclosure
18 requirements for inspections, maintenance, monitoring, institutional controls, and periodic assessments at
19 the site during a modified closure period would be in accordance with a postclosure permit application.
20 This closure plan would be revised to include the conditions of modified closure as stipulated in a
21 postclosure permit application if modified closure occurs.
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