limiteci-M.--shedsrenelosed-lean4os:ramp-houses.

small-animal-housing,

Record of Modification to the

Response Action Work Plan (RAWP) Revision 6.0

Modification Number: 052914-03 (six-digit date code — sequential number

Date: 05/29/2014

Section to be Modified:

4.7 Vermiculite and ACS Removal from Secondary Buildings and Structures

4.7.1 Definitions

Secondary buildings and secondary structures are fully defined in CDM-Libby-06 Site-specific

Procedure for Semi-Quantitative Visual Estimation of Vermiculite. This procedure is provided in

Appendix B of the General Property Investigation Quality Assurance Project Plan (CDM Smith

2014, or current revision).

Once the RC has completed removal of all gmss-visible-vennieulite ral4 vinibleNemneuliter and all ACS to planned depth, TQA will be notified to facilitate inspection and collection of

confirmation samples. Confirmation sampling will be conducted in accordance with the

Response Action Sampling and Analysis Plan (CDM 2011b, or current revision).

VCI removals within enclosed secondary structures will follow interior removal process as stated

in section four of this document.

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Details regarding action levels and clearance criteria are found in the Libby Asbestos Site

Residential/Commercial Cleanup Action Level and Clearance Criteria Technical Memorandum

(EPA 2003) and its revisions. Action levels and clearance criteria are subject to revision by the

EPA.

4.7.21'1:Inning and Removal Process

Finished secondary buildings with solid-construction floors (e.g.. concrete, wood, etc.) will

undergo removal actions similar to a primary building.

Secondary buildings often include unfinished, soil floors. Contaminated soil within a building

presents unique removal challenges. In general, removal will be completed with a combination

of interior and exterior techniques. The following steps will be followed for addressing the soil

floor of a secondary building in which Eleteetable4evels-of greater than or equal to one percent

LA is detected.

1. Complete vermiculite insulation removal (attic) in accordance with Section 2

2. Remove and clean or dispose of all items within the building

3. Complete a bulk/gross cleaning of the interior

4. Excavate soil floor to a depth of 6-inches below ground surface (bgs)

5. Contain interior of building (negative pressure enclosure/containment)

6. Detail clean interior of building

7. Collect soil clearance samples

8. Backfill the floor of the excavated area (area will still be considered within the exclusion

zone)

9. Return all items back into the structure

10. Collect air clearance samples

11. Remove NPE after clearance has been achieved

12. Complete backfilling, if necessary

If a secondary buildings has only soil contamination with analytical results of less than one

percent or trace LA and is called out on the work plan for removal, the removal will follow the

process listed above except negative pressure enclosure and final air clearance is not required.

Negative pressure enclosure and final air clearance may be conducted at the direction of

USACE/EPA.

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Soil areas within secondary structures will be treated as normal excavation. No additional cleaning is required.

. Negative pressure enclosure and final air clearance will not be required. Due to potential for undermining the foundation, excavation within secondary

structures will typically be limited to a minimum of 6 -inches bgs. All excavation and restoration will be conducted in accordance with Section 3 and Section 4.

Attach the referenced section to this record. Strike the language to be removed. Underline additions to existing language.

Si m ature Name Date

6 /,, WiV EPA Approval: bk--62-------. itt.a.,9-e. ( e.. ( (- fat._ USAGE Approval: r-Ired, ------

DM855. ----- Lawrence J. Woscyna 6/24/14

A&E Approval: = 1.417-10^NS . .aest_- G -t9 - I r G. 43-74/ RC Approval: "Ilizokic.L. .3--Acgsr..) n

04

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