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RECORD OF DECISION REMEDIAL ALTERNATIVE · PDF fileARF# 14673 RECORD OF DECISION REMEDIAL...

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ARF# 14673

United States Department of Energy

Savannah River Site

Record of Decision Remedial Alternative Selectionfor the A-Area Burning/Rubble Pits (731-A, -1A) andRubble Pit (731-2A) and the Miscellaneous Chemical Basin /Metals Burning Pit (731-4A, -5A) Operable Unit (U)

CERCLIS Numbers: 19,28

WSRC-RP-2005-4095

Revision 1.1

February 2007

Prepared by:Washington Savannah River Company LLCSavannah River SiteAiken, SC 29808Prepared for U.S. Department of Energy under Contract No. DE-AC09-96SR18500

10450085

ROD for the ABRP/MCB/MBP (U) WSRC-RP-2005-4095Savannah River Site Rev. 1.1February 2007

DISCLAIMER

This report was prepared by Washington Savannah River Company LLC(WSRC) for the United States Department of Energy under Contract No.DE-AC09-96SR18500 and is an account of work performed under thatcontract. Reference herein to any specific commercial product, process, orservices by trademark, name, manufacturer or otherwise does notnecessarily constitute or imply endorsement, recommendation, or favoring ofsame by WSRC or the United States Government or any agency thereof.

Printed in the United States of America

Prepared forU.S. Department of Energy

andWashington Savannah River Company LLC

Aiken, South Carolina

IS84RDPdoc

ARF# 14673

RECORD OF DECISIONREMEDIAL ALTERNATIVE SELECTION (U)

A-Area Burning/Rubble Pits (731-A, -1A) and Rubble Pit (731-2A) and the MiscellaneousChemical Basin/Metals Burning Pit (731-4A, -5A) Operable Unit (U)

CERCLIS Numbers: 19, 28

WSRC-RP-2005-4095Revision 1.1

February 2007

Savannah River SiteAiken, South Carolina

Prepared by:

Washington Savannah River Company LLCfor the

U. S. Department of Energy under Contract DE-AC09-96SR18500Savannah River Operations Office

Aiken, South Carolina

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ROD for the ABRP/MCB/MBP (U) WSRC-RP-2005-4095Savannah River Site Rev. 1.1February 2007

This page was intentionally left blank.

ARF # 14673ROD for the ABRP/MCB/MBPSavannah River SiteFebruary 2007

WSRC-RP-2005-4095Rev. 1.1

Declaration i of xii

DECLARATION FOR THE RECORD OF DECISION

Unit Name and Location

A-Area Burning/Rubble Pits (731-A, -1A) and Rubble Pit (731-2A) and the MiscellaneousChemical Basin/Metals Burning Pit (731-4A, -5 A) Operable Unit

Comprehensive Environmental Response, Compensation, and Liability Information System(CERCLIS) Identification Numbers: OU- 19, 28

Savannah River Site

Comprehensive Environmental Response, Compensation and Liability Act (CERCLA)Identification Number: SCI 890 008 989

Aiken, South Carolina

United States Department of Energy

The A-Area Burning/Rubble Pits (731-A, -1A) and Rubble Pit (731-2A) (ABRP) and

Miscellaneous Chemical Basin/Metals Burning Pit (731-4A, -5A) (MCB/MBP) Operable Units

(OU) are listed as separate Resource Conservation and Recovery Act (RCRA) 3004(u) Solid

Waste Management Unit / CERCLA units in Appendix C of the Federal Facility Agreement

(FFA) for the Savannah River Site (SRS). To achieve final closure, the individual units have

been consolidated to form the ABRP/MCB/MBP OU.

The FFA is a legally binding agreement between regulatory agencies [United States

Environmental Protection Agency (USEPA) and South Carolina Department of Health and

Environmental Control (SCDHEC)] and the regulated entity [United States Department of

Energy (USDOE)] that establishes the responsibilities and schedules for the comprehensive

remediation of the SRS. The ABRP/MCB/MCP OU includes the A-Area Ash Pile (788-2A).

The media associated with this OU are surface and vadose zone soils. Groundwater is not

considered part of the scope for the ABRP/MCB/MBP OU. Any groundwater contamination

resulting from the ABRP/MCB/MBP OU is regulated by the SRS RCRA Part B Permit and

addressed by the requirements of the M-Area and Metallurgical Laboratory Hazardous Waste

Management Facilities Groundwater Monitoring and Corrective Action agreements.

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ROD for the ABRP/MCB/MBP WSRC-RP-2005-4095Savannah River Site Rev. 1.1February 2007 Declaration ii of xii

Statement of Basis and Purpose

This decision document presents the selected remedy for the ABRP/MCB/MBP OU, located at

the SRS near Aiken, South Carolina. The remedy was chosen in accordance with CERCLA, as

amended by the Superfund Amendments Reauthorization Act (SARA), and, to the extent

practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This

decision is based on the Administrative Record File for this site. USEPA, SCDHEC and USDOE

concur with the selected remedy.

Assessment of the Site

There has been a release of hazardous and radioactive substances at the ABRP/MCB/MBP OU to

the environment. The response actions selected in this Record of Decision (ROD) are necessary

to protect the public health or welfare or the environment from actual or threatened releases of

hazardous substances to the environment.

Description of the Selected Remedy

The ABRP/MCB/MBP OU is comprised of the following subunits:

ABRP OU

Burning/Rubble Pit 731 -A Subunit

Burning/Rubble Pit 731 -1A Subunit

Rubble Pit 731-2A Subunit

Potential Pit Subunit

Depressional Area Subunit

Ash Scatter Area/Ditch Subunit

ISMRDP.doc

ARF# 14673

ROD for the ABRP/MCB/MBPSavannah River SiteFebruary 2007

WSRC-RP-2005-4095Rev. 1.1

Declaration iii of xii

Trench Subunit (includes vadose zone soil)

788-2A A-Area Ash Pile Subunit

MCB/MBP OU

MCB Surface Soil Subunit

MCB Vadose Zone Subunit

MBP Surface Soil Subunit

For the ABRP/MCB/MBP OU, no action is required for the following subunits:

Burning/Rubble Pits 731 -A and 731 -1A

Depressional Area

Potential Pit

Ash Scatter Area/Ditch

This decision is based on a hypothetical future resident scenario i.e., unrestricted land use. These

subunits do not require any surficial land use controls as part of the final remedy.

As per the respective Interim Records of Decision (IROD), final actions have been completed for

the following subunits and no further action is required:

Rubble Pit 731-2A

MCB/MBP surface soils

The decisions for the Rubble Pit and MCB are based on the future industrial worker scenario;

these subunits require land use controls as part of the final remedy. The MBP does not require

ISMRDPdoc

ROD for the ABRP/MCB/MBP WSRC-RP-2005-4095Savannah River Site Rev. 1.1February 2007 Declaration iv of xii

surface land use controls (based on a hypothetical future resident scenario, i.e., unrestricted land

use) as part of the final remedy since it only had an ecological risk driver.

A final action for the MCB vadose zone is on-going and will continue. The final action is the

continued passive operation of soil vapor extraction (SVE) BaroBall wells. The future land

use for ABRP/MCB/MBP OU is anticipated to be industrial. Due to groundwater contamination,

institutional controls to prevent access or use of groundwater until cleanup levels are met under

the RCRA program are required for all of the subunits in this operable unit. Groundwater

contamination in the vicinity of the ABRP/MCB/MBP OU is being addressed under the 2000

RCRA Part B Permit Renewal Application for M-Area and Metallurgical Laboratory Hazardous

Waste Management Facilities Postclosure.

Based on the detailed evaluation of alternatives performed in the Corrective Measures

Study/Feasibility Study (CMS/FS), the selected remedies for final remedial actions for the

ABRP/MCB/MBP OU include the following:

Trench Subunit

Alternative AT-3 - Operation of SVE and Institutional Controls: This alternative involves

operating an SVE system and implementing institutional controls until the vadose zone RAOs

have been achieved. This alternative has been selected because it effectively removes volatile

organic compounds (VOCs) from the vadose zone and protects groundwater by depleting the

source. The final SVE system would be an expansion of the existing Interim Remedial Action

(IRA) well network. The existing system consists of three MicroBlower and one BaroBall

vapor-extraction wells to target contamination in the vadose zone beneath the Trench. The

expanded system would include installation of up to an additional 11 SVE wells. System air

emissions do not require treatment and are vented to the atmosphere. The ABRP and MCB SVE

systems received an Air Quality Control (AQC) permit exemption because of the expected (and

demonstrated) low exhaust emissions. SRS plans to pursue a similar strategy for future SVE

systems in the area.

IS84RDP.doc

ARF# 14673ROD for the ABRP/MCB/MBPSavannah River SiteFebruary 2007

WSRC-RP-2005-4095Rev. 1.1

Declaration v of xii

USDOE, USEPA, and SCDHEC have agreed to jointly decide on significant changes in the

operation of the SVE system (typically transitioning from active to passive extraction) taken to

maintain the efficiency of the remedial system. This process for transition from active to passive

SVE technology will be discussed in detail in the Corrective Measures Implementation

(CMI)/

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