ML071670009

Yankee Nuclear Power Station, Groundwater Monitoring Plan to Support Closure Under the Massachusetts Contingency Plan

ML071670009
Person / Time
Site:	Yankee Rowe
Issue date:	09/01/2006
From:	Jeffery Lynch Yankee Atomic Electric Co
To:	Howland D NRC/FSME, State of MA, Dept of Environmental Protection
References
BYR 2006-075
Download: ML071670009 (35)

Text

YANKEE ATOMIC ELECTRIC COMPANY Telephone (413) 49 Yankee Road, Rowe, Massachusetts 01367 Y KJEE September 1,2006 BYR 2006-075 Massachusetts Department of Environmental Protection DEP Western Region 436 Dwight Street Suite 402 Springfield, MA 01103 Attention: Mr. David Howland

Subject:

Groundwater Monitoring Plan to Support Closure under the Massachusetts Contingency Plan

Dear Mr. Howland:

Please find enclosed three (3) copies of the "Groundwater Monitoring Plan to Support Closure under the Massachusetts Contingency Plan" (GMP-MCP) for Department review, comment and/or approval. The GMP-MCP was prepared at the request of the Massachusetts Department of Environmental Protection (Department) and presents Yankee Atomic Electric Company's (YAEC's) proposed plans for groundwater monitoring necessary to support closure of the Yankee Nuclear Power Station (YNPS) site in Rowe, Massachusetts in accordance with the requirements of the Massachusetts Contingency Plan (MCP, 310 CMR 40.0000) for a Permanent Solution.

As you are aware, YAEC has prepared a separate plan, "Groundwater Compliance Plan For License Termination Plan For The Yankee Nuclear Power Station ", (GMP-LTP) that outlines plans to conduct groundwater monitoring to satisfy Nuclear Regulatory Commission (NRC) requirements for License Termination. The GMP-LTP document is included as Appendix A of the GMP-MCP.

Should you have questions or require additional information, please contact us.

Sincerely, YANKEE ATOMIC ELECTRIC COMPANY JosegphR. Lyn h Regulatory Affairs Manager

MA Department of Environmental Protection Western Region Office BYR 2006-075, Page 2 of 2

Attachment:

Groundwater Monitoring Plan to Support Closure under the Massachusetts Contingency Plan cc:

L. Hansen, MA DEP (WRO)

T. Kurpaska, MA DEP (WRO)

N. Bettinger, MA DEP (Boston)

R. Walker, Director, Radiation Control Program, MA DPH M. Whalen, Radiation Control Program, MA DPH L. Dunlavy, Franklin Regional Council of Government P. Sloan, Greenfield Director of Planning & Development W. Perlman, Franklin Regional Planning Board T. Hutcheson, Franklin Regional Planning Board M. Rosenstein, US EPA, Chemicals Management Branch Chief M. Ballew, US EPA, Region I (Boston)

P. Newkirk, US EPA, Headquarters K. Tisa, US EPA, Region I, TSCA Coordinator J. Hickman, NRC Project Manager S. Collins, NRC, Region I Administrator M. Miller, NRC, Chief, Decommissioning Branch, NRC Region I D. Everhart, Inspector, NRC Region I J. Kotton, Inspector, NRC Region I D. Katz, Citizen's Awareness Network J. Block, Esq.

R. Ross, CAN Hydrogeologist Public Repository at Greenfield Community College

I I ý

-. O-'-Cal)s Groundwater Monitoring Plan to Support Closure under the Massachusetts Contingency Plan Yankee Nuclear Power Station Site Closure Project Rowe, Massachusetts 1 September 2006 ERM 399 Boylston St.

Boston, MA 02116 (617) 646-7800 www.erm.com ERM Delivering sustainable solutions in a more competitive world

Yankee Atomic Electric Company Groundwater Monitoring Plan to Support Closure under the Massachusetts Contingency Plan Yankee Nuclear Power Station Site Closure Project Rowe, Massachusetts 1 September 2006 John W. McTigue, P.G., LSP Principal-in-Charge

For, LSP Environmental Resources Management 399 Boylston Street, 6t Floor Boston, Massachusetts 02116 T: 617-646-7800 F: 617-267-6447

EXECUTIVE

SUMMARY

III 1.0 PURPOSE & SCOPE 1

2.0

SUMMARY

OF GROUNDWATER MONITORING AT YNPS 2

2.1 HISTORY OF GROUNDWATER WELL MONITORING AT YNPS 2

2.2

SUMMARY

OF SITE GEOLOGY & HYDROGEOLOGY 4

2.3

SUMMARY

OF NATURE, EXTENT, TRANSPORT & FATE OF GROUNDWATER IMPACTS 5

2.3.1 Nature & Extent of Groundwater Impact 5

2.3.2 Transport & Fate of Groundwater Impact 6

3.0 GROUNDWATER REGULATORY REQUIREMENTS & PROPOSED COMPLIANCE PLAN 8

3.1 NUCLEAR REGULATORY COMMISSION REQUIREMENTS &

COMPLIANCE PLAN 8

3.2 MASSACHUSETTS REQUIREMENTS & COMPLIANCE PLAN 8

4.0 YAEC'S PROPOSED GROUNDWATER MONITORING PLAN 12 4.1 RADIOLOGICAL GROUNDWATER MONITORING PLAN 12 4.2 OHM GROUNDWATER MONITORING PLAN 13 4.3 WELL CLOSURES 14 ERM YAEC 0043964 SEP 2006 ERM i

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TABLES Table 1 Summary of Monitoring Well Specifications Table 2 Summary of Contaminants in Groundwater Table 3 MCP Groundwater Monitoring Parameters FIGURES Figure 1 Locus Map Figure 2 Monitoring Well Network APPENDICES Appendix A Groundwater Compliance Plan For License Termination Plan For The Yankee Nuclear Power Station Appendix B Tritium Risk-Based Concentration in Drinking Water ERM ii YAEC 0043964 SEP 2006 ERM ii YAEC 0043964 SEP 2006

EXECUTIVE

SUMMARY

Yankee Atomic Electric Company (YAEC) retained Environmental Resources Management (ERM) to prepare this Groundwater Monitoring Plan to Support Closure under the Massachusetts Contingency Plan (GMP-MCP) for the Yankee Nuclear Power Station (YNPS) located in Rowe, Massachusetts (the "site"). This GMP-MCP was prepared to support Massachusetts Department of Environmental Protection's (MA DEP's) review and approval of proposed plans for long-term groundwater monitoring at the YNPS. YAEC has prepared a separate plan, Groundwater Compliance Plan For License Termination Plan For The Yankee Nuclear Power Station, to outline plans to conduct groundwater monitoring to satisfy Nuclear Regulatory Commission (NRC) requirements (Appendix A).

A total of 78 groundwater monitoring wells have been installed at the site since 1977. Of those, 25 have been closed during the course of decommissioning activities. YAEC is installing three additional shallow monitoring wells to support site closure.

The GMP-MCP outlines plans for sampling groundwater for radiological parameters and Oil and/or Hazardous Materials (OHM). Groundwater sampling will be conducted at least annually. A more frequent sampling program may be implemented if deemed appropriate to facilitate site closure (e.g., sampling rounds could be conducted annually, semi-annually, or at a maximum frequency, quarterly).

Based on a review of historic data, tritium was the only radiological parameter carried forward in the GMP-MCP. Sampling will be performed at the one well (MW-107C) where tritium has been detected above the Maximum Contaminant Level (MCL), along with eight other wells where tritium has been detected at 25 % of the MCL. Monitoring for tritium will be performed at least annually at MW-107C until results from four consecutive quarterly rounds completed over a one-year period are below the MCL. Monitoring will be performed at the other eight wells until monitoring is completed at MW-107C, or when the tritium concentration is less than 25 % of the MCL for two consecutive sampling events.

Results of historic monitoring for OHM were compared to the Massachusetts Contingency Plan (MCP) Reportable Concentrations for Groundwater Category GW-1 (RCGW-1). Results indicate sporadic detections of OHM above RCGW-1 that were generally not repeatable, not ERM iii YAEC 0043964 SEP 2006

associated with a release condition, or due to well integrity issues (e.g.,

polychlorinated biphenyl-containing paint chips found in damaged wells, glue used in above ground temporary risers during re-grading, etc.).

Nonetheless, sampling for OHM constituents will be conducted at least annually at 19 monitoring wells. Monitoring will be conducted until the results of two consecutive sampling events demonstrate that OHM levels are below RCGW-1 Standards (or an alternative risk-based standard agreed to by YAEC and MA DEP).

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1.0 PURPOSE & SCOPE Yankee Atomic Electric Company (YAEC) retained Environmental Resources Management (ERM) to prepare this Groundwater Monitoring Plan to Support Closure under the Massachusetts Contingency Plan (GMP-MCP) for the Yankee Nuclear Power Station (YNPS) located in Rowe, Massachusetts (the "site") (Figure 1). This GMP-MCP was prepared to support Massachusetts Department of Environmental Protection's (MA DEP's) review and approval of proposed plans for long-term groundwater monitoring at the YNPS. This plan includes:

Section 2.0 Summary of Groundwater Monitoring at YNPS A description of the history of groundwater monitoring, the existing well network, site geology and hydrogeology, and a brief summary of the known nature and extent and fate and transport of contaminants in site groundwater.

Section 3.0 Groundwater Regulatory Requirements & Proposed Compliance Plan A brief summary of state and federal regulatory requirements governing groundwater monitoring, criteria for termination of monitoring and YAEC's proposed pathway to satisfy regulatory requirements.

Section 4.0 YNPS Proposed Groundwater Monitoring Plan A summary of proposed monitoring locations, frequency, analytical parameters, quality assurance/ quality control and reporting procedures.

YAEC has prepared a separate plan to outline groundwater monitoring that will be conducted to satisfy Nuclear Regulatory Commission (NRC) requirements. A copy of the Groundwater Compliance Plan For License Termination Plan For The Yankee Nuclear Power Station (GMP-LTP) is provided in Appendix A. In addition, monitoring of the former Southeast Construction Fill Area will be conducted to address the requirements of the Massachusetts Solid Waste Regulations, but is not addressed in this GMP-MCP.

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2.0

SUMMARY

OF GROUNDWATER MONITORING AT YNPS 2.1 HISTORY OF GROUNDWATER WELL MONITORING AT YNPS Groundwater investigations began at YNPS in 1977 with the installation of the first monitoring well. Since 1977, a total of 78 monitoring wells have been installed. While 25 of these have been abandoned during site decommissioning, the remaining 53 support ongoing monitoring of site groundwater quality. A brief summary of primary well installation/ abandonment events is provided below:

" Prior to 2003, 34 monitoring wells were installed at various times to investigate the shallow stratified drift aquifer.

" In 2003 and 2004, a comprehensive subsurface investigation program was initiated to evaluate groundwater quality deeper in the overburden beneath the shallow stratified drift deposits and into the underlying bedrock aquifer. This program included collection of continuous soil and rock cores and installation of 27 wells as a single, couplet or triplet monitoring point, including:

o Four wells in the shallow stratified drift; o 13 wells in sand lenses interlayed within a lodgment till overlying the bedrock; and o 10 wells into the bedrock.

In 2006, an additional 17 wells were installed to further define the extent of groundwater impact detected in previous events. This investigation focused on further characterization of groundwater quality in and around the Ion Exchange (IX) Pit and the Spent Fuel Pool (SFP) as the most significant suspected source of tritium in groundwater and the down-gradient extent of impact, including:

o Nine wells in three well clusters to investigate the IX Pit (MW-110A, B, C, D), the SFP (MW-111A, B, C), and the Septic System Leachfield (MW-113A, B);

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o Five shallow wells to bound the highest shallow tritium groundwater concentration (MW-101A, -102D, -104A, -107A,

-109A);

o Two wells to investigate the highest deep tritium groundwater concentration (MW-107E, F); and o One shallow well to investigate potential non-radiological impact down-gradient of the former Service Building (MW-105A).

Plant decommissioning activities necessitated the closure/abandonment of a total of 25 monitoring wells. These were generally older, shallow wells that were either damaged and of questionable integrity, duplicative of the current monitoring well network, or not worth maintaining during site re-grading, including:

" In July 2004, the following six wells were closed: B-i, CB-10, CB-11A, CW-11, CW-8, and MW-1.

" In November 2004, the following 16 wells were closed: CB-1, CB-12, CB-5, CB-7, CB-9, CFW-2, CFW-3, CFW-4, CFW-7, CW-3, CW-4, CW-5, MW-2, MW-5, MW-6, and OSR-1.

" In August 2005, the following three wells were closed: CB-2, CW-6, and CW-7.

Specifications for the remaining 53 monitoring wells are provided in Table 1. Well locations are displayed in Figure 2.

Additional wells are currently being installed which include two historic monitoring locations that were previously closed (CW-5 and MW-6) and two new monitoring locations (MW-112A and MW-104D) (Figure 2).

Since 2003, 12 comprehensive groundwater sampling events have been completed including analyses for both radiological and non-radiological contaminants. Characterization of groundwater quality for radiological contaminants is summarized in Table 3-4 of Appendix A.

Characterization of groundwater for Oil and/or Hazardous Materials (OHM) included the following:

" Gasoline Range Organics (GRO) by GC, SW-846 Method 8015B;

" Diesel Range Organics (DRO) by GC, SW-846 Method 8015B; ERM YAEC 0043964 SEP 2006

• Extractable Petroleum Hydrocarbons (EPH), Volatile Petroleum Hydrocarbons (VPH), and target analytes by MADEP Methods MADEP-EPH-98-1 and MADEP-VPH-98-1;

• Semi-Volatile Organic Compounds (SVOCs) by GC/ MS, SW-846 Method 8270C SVOCs, SIM analysis;

• Volatile Organic Compounds (VOCs) by GC/MS, SW-846 Method 8260B;

• Polychlorinated Biphenyls (PCBs) total and dissolved by GC, SW-846 Method 8082; 0 Herbicides by GC, SW-846 Method 8151; 0 Alcohols by FID Method ASTM D3695; and 0 Priority Pollutant Metals (PP13), boron, and lithium by SW-846 Method 6010B.

2.2

SUMMARY

OF SITE GEOLOGY & HYDROGEOLOGY Results of subsurface investigations have resulted in the development of a Site Conceptual Model (SCM) that summarizes the site geology and hydrogeology. The SCM is described in detail in the GMP-LTP (Appendix A). The SCM describes the site as being comprised of the following four hydrogeologic units:

" Stratified Drift-a relatively permeable sand ranging in thickness from zero to 40 feet that contains the water table at depths ranging from 4 to 20 feet below ground surface in the central portion of the site.

" Glacial Till-a relatively impermeable mix of sand, silt and clay that is very dense and compact underlying the stratified drift. Till has been encountered from zero to 210 feet below ground surface across the site.. Groundwater within this unit is confined/semi-confined to silty. sand lenses that are up to a few feet in thickness and laterally discontinuous.

• Lake Deposits-an alternating sequence of fine silt and clay that is laminated (glaciolacustrine deposits) underlying the till at a depth ERM 4

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of 100 feet below ground surface in the northern portion of the site.

Bedrock-an albite gneiss encountered at depths ranging from zero to 210 feet below ground surface. The upper surface of the bedrock appears to be moderately fractured and capable of yielding a few gallons per minute.

The rate and direction of groundwater flow beneath the site varies depending on location and hydrogeologic unit, but is generally northwest to west toward the Deerfield River. The rate of flow is greatest in the shallow stratified drift. Groundwater flow in the underlying till, lake deposits and bedrock is subject to both confined and semi-confined flow conditions due to the dense and laterally heterogeneous nature of these units. Flow in these units is estimated to be substantially slower than the stratified drift, but is generally toward the Deerfield River. The Deerfield River is estimated to represent the western, down-gradient extent of groundwater flow, which eventually discharges to river surface water.

2.3

SUMMARY

OF NATURE, EXTENT, TRANSPORT & FATE OF GROUNDWATER IMPACTS 2.3.1 Nature & Extent of Groundwater Impact Tritium A detailed review of site groundwater monitoring for radioactive contaminants is included in Appendix A. Results indicate that the only radiological contaminant of concern in groundwater is tritium. The primary source of tritium release appears to have been leakage of cooling water contained in the SFP/IX Pit, which was recently excavated and removed (2005/2006).

A tritium plume has been identified in the shallow stratified drift originating from beneath the former footprint of the plant and extending northwest/west toward the Deerfield River. The highest concentrations of tritium detected in this shallow plume are 16,900 pCi/L (based on April 2006 result at MW-101A) at the plant and decreasing to 7,620 pCi/L (at MW-106A in July 2006) near the Deerfield River. Tritium levels in this plume have been below the Environmental Protection Agency (EPA)

Maximum Contaminant Level (MCL) for drinking water of 20,000 pCi/L.

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Tritium has been confirmed at a concentration above the EPA MCL in only one monitoring well, MW-107C, located within a sand lens in the till just below the outwash. The highest level of tritium detected at MW-107C was 48,000 pCi/L in September 2003. The level of tritium in MW-107C has decreased to 36,600 pCi/L (July 2006). Detected impacts at all other wells remain below the EPA MCL.

The distribution of tritium in the shallow stratified drift is consistent with the advective flow of groundwater down-gradient to the northwest/west of the plant. Concentrations tend to decrease down-gradient due to dilution and dispersion with increasing distance from the plant. Tritium in the underlying till is limited to confined/semi-confined sand lenses that appear to be laterally discontinuous, thereby limiting down-gradient transport, dilution or dispersion and resulting in the tritium level remaining above the EPA MCL at one monitoring point (MW-107C).

OHM Results of monitoring for OHM were compared to the Massachusetts Contingency Plan (MCP) Reportable Concentrations for Groundwater Category GW-1 (RCGW-1). Table 2 summarizes wells where target OHM were detected above RCGW-1. Results indicate sporadic detections of OHM above RCGW-1 Standards that were generally not repeatable, not associated with a potential site release condition, or were found to be associated to well integrity issues (e.g., polychlorinated biphenyls (PCBs) in groundwater within damaged wells where PCB-containing paint chips infiltrated with storm water, or volatile organic compounds (VOCs) found in wells where glue containing the same VOCs had been used to attach temporary risers pipes during re-grading).

At least one additional round of monitoring will be conducted to confirm site groundwater quality results for OHM prior to site closure. Locations confirming OHM below RCGW-1 would be excluded from further monitoring, while any above would continue to be monitored until at least two consecutive rounds demonstrate OHM below RCGW-1 Standards.

2.3.2 Transport & Fate of Groundwater Impact Tritium is the primary contaminant of concern (COC) in site groundwater.

All liquid sources of tritium release have been removed. A tritium plume exists in the relatively permeable upper stratified drift and flows to the west discharging to the Deerfield River. The highest concentrations of tritium in the shallow plume are below the EPA MCL. These levels are ERM 6

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expected to continue to decrease via dilution, dispersion and radioactive decay (tritium half-life is approximately 12 years).

Tritium has been detected in the deeper confined/semi-confined sand lenses within the underlying till. Tritium concentrations in this unit have been found to exceed the EPA MCL at only one monitoring point (MW-107C). The laterally discontinuous, disconnected nature of these lenses within very tight till limits dilution or dispersion resulting in minimal dilution of tritium over time. While groundwater within these lenses may slowly migrate to surface water, it is likely that dilution, dispersion and radioactive decay of tritium will reduce the concentrations to negligible levels prior to discharge to surface water.

Groundwater down-gradient of MW-107C is not currently, and in the future is unlikely to be, used as a source of drinking water. Nevertheless, groundwater monitoring will be conducted in accordance with the GMP-LTP and the GMP-MCP to establish that tritium concentrations continue to decrease as expected below the EPA MCL.

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3.0 GROUNDWATER REGULATORY REQUIREMENTS & PROPOSED COMPLIANCE PLAN 3.1 NUCLEAR REGULATORY COMMISSION REQUIREMENTS &

COMPLIANCE PLAN Nuclear Regulatory Commission (NRC) site closure requirements for groundwater are stipulated in the YNPS License Termination Plan (LTP),

NRC License Amendment No. 158. The GMP-LTP identifies the following criteria that must be met to satisfy LTP License Amendment No. 158:

" Demonstration that site-generated radionuclides, with the exception of tritium, are not present in groundwater above the.

limits presented in LTP License Amendment No. 158.

" An evaluation to demonstrate that maximum concentration of tritium in a well capable of supplying a resident farmer does not exceed 20,000 pCi/L.

" An evaluation to demonstrate that tritium concentrations in down-gradient off-site wells are less than 20,000 pCi/L.

Compliance with these criteria will be based on five rounds of quarterly monitoring conducted beginning in the Spring of 2006 and ending in the Spring of 2007.

3.2 MASSACHUSETTS REQUIREMENTS & COMPLIANCE PLAN Under the Massachusetts Contingency Plan (MCP) 310 CMR 40.0000 site closure must meet the performance standards of a Permanent Solution for a Class A Response Action Outcome (RAO) Statement, or a Temporary Solution for a Class C RAO, until a Permanent Solution is achieved.

Performance standards for achievement of a Permanent Solution include:

Demonstration that residual concentrations of OHM (including tritium) do not pose a condition of "significant risk." Using quantitative risk estimation protocols the MCP carcinogenic risk-based threshold is a risk of 1 x 10-5. For tritium, if no other significant risk contributors exist, the risk threshOld corresponds to ERM 8

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an estimated concentration of 23,000 pCi/L using standard DEP default exposure assumptions (Appendix B).

Demonstration that residual concentrations of OHM (including tritium) do not pose a condition of "significant risk" by complying with applicable or suitably analogous regulatory standards. For tritium this includes the EPA MCL of 20,000 pCi/L, which is adopted by Massachusetts under 310 CMR 22.09A.

YAEC anticipates that in 2007 a Permanent Solution as a Class A RAO-Partial (RAO-P) will be filed for the majority of the site that does not pose a "significant risk." YAEC anticipates that this will include areas where soil could pose a "significant risk", but where a deed restriction and/or Activity and Use Limitation (AUL) will be filed to prevent activities and uses that could result in adverse exposure. Therefore, YAEC anticipates that the majority of the site would be eligible for a Class A-3 RAO-P.

However, the presence of tritium, and/or other OHM in site groundwater, at concentrations exceeding an applicable or suitably analogous regulatory standard constitutes, by definition under the MCP, a condition of "significant risk" that prevents filing a Permanent Solution as a Class A RAO-P in those portions of the site. At this time, YAEC anticipates that the only groundwater condition remaining at the site that will meet the definition of a condition of "significant risk" will be the presence of tritium in groundwater at monitoring well MW-107C. If so, the Class A-3 RAO-P would exclude the area surrounding MW-107C where groundwater has the potential to exceed the drinking water standard.

YAEC anticipates that the portion of the site to be excluded from the Permanent Solution would be eligible for a Temporary Solution as a Class C RAO-P, or transitioned into a Remedy Operation Status (ROS) in support of a Monitored Natural Attenuation (MNA) remedy for groundwater (described below). The exact boundaries of the RAO-P will be determined after additional groundwater monitoring. is conducted and the cumulative risk assessment is completed.

YAEC intends to utilize MNA to address the residual tritium impacts in groundwater. Active abatement via groundwater pump and treat does not appear to be a viable option since:

1. Pumping extensive volumes of groundwater from the construction excavations during source removal had no significant effect on the levels of tritium in MW-107C. The groundwater was discharged to surface water under a National Pollution Discharge Elimination System permit for ERM 9

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construction dewatering. Hydraulic pump testing of MW-107C also resulted in minimal yield and no reduction in tritium concentrations. These results suggest that recovery via pumping is not feasible due to the very low yield of the sand lens in which this well screen is completed.

2. There is no available treatment technology for tritium in groundwater, either on or off-site. MA DEP has stated that discharge to surface water without treatment, as was done during the excavation activities, would not be an acceptable remedial alternative for the site.

3. Off-site disposal of large volumes of water would not be feasible from a risk-reduction/cost-benefit standpoint in considering that this would generate a costly waste stream and increase short-term risk.

There are two MCP regulatory filing options for addressing the portion of the site that will not be the subject of the Permanent Solution, including:

1) a Temporary Solution as a Class C-2 RAO-P; or 2) to file a ROS for MNA for groundwater. The. bases for these alternatives are:

1. The infeasibility (considering risk reduction and cost-benefit) of abatement to achieve a Permanent Solution.

2. Site conditions would meet risk-based performance standards for a Temporary Solution including elimination of a "substantial hazard" (no risk in the short-term/several years, because there is no current exposure pathway as no one is drinking the water, but potential for long-term risk based on tritium remaining above an MCL and the potential for groundwater to be used as a future source of drinking water, since there are no alternate potable public water supplies in the vicinity of the site).

3. MNA is anticipated to result in the achievement of a Permanent Solution for the site.

Under a Class C-2 RAO-P or ROS, groundwater monitoring would continue for a period of five to ten years at which point natural attenuation and radioactive decay of tritium is anticipated to reduce the levels below the MCL. YAEC anticipates that a decision regarding a Class C-2 RAO-P or ROS filing will be reached following evaluation of groundwater monitoring results for the Spring 2007 event (completion of monitoring to support NRC requirements). Once it was demonstrated ERM 10 YAEC 0043964 SEP 2006

through additional groundwater monitoring that the levels of tritium are permanently reduced below the MCL, a Permanent Solution (Class A-3 RAO) will be filed for the remainder of the site and groundwater monitoring will be terminated.

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4.0 YAEC'S PROPOSED GROUNDWATER MONITORING PLAN 4.1 RADIOLOGICAL GROUNDWATER MONITORING PLAN Appendix A includes the GMP-LTP. This report includes the radiological groundwater monitoring plan that will be conducted in accordance with the License Termination Plan (LTP) and Nuclear Regulatory Commission (NRC) License Amendment No. 158. Quarterly groundwater sampling.

(with additional sampling for tritium at select wells) was proposed to begin in Spring 2006 and conclude no earlier than Spring 2007.

Radiological sample parameter lists and QA/QC requirement are discussed in Appendix A.

To satisfy MCP requirements, at least annual monitoring for tritium will be conducted at selected well locations based on the following rationale:

1. MW-107C due to levels in excess of the MCL.

2. Additional wells where tritium had been detected at levels exceeding 25 % of the MCL or greater than 5,000 pCi/ L, including.

The following wells meet this criterion based on a preliminary review of the data:

" MW-107A, MW-107D, MW-107E, MW-107F

• MW-101A MW-102D

• MW-106A (a down-gradient well)

" MW-111C Monitoring is expected to continue at least annually until the levels of tritium in MW-107C naturally decay permanently below the MCL. Once monitoring results indicate levels have decayed below the MCL, a permanent reduction in the levels of tritium in MW-107C will be established based on generating four consecutive quarterly monitoring rounds over a one-year period indicating tritium at levels below the MCL of 20,000 pCi/L.

Monitoring of tritium levels at each of the additional wells will continue until either: 1) titium concentrations from two consecutive sampling events are below 25% of the MCL or 5,000 pCi/L); or 2) tritium concentrations in MW-107C are consistently below the MCL (based on results from four consecutive quarterly monitoring events). In this ERM 12 YAEC 0043964 SEP 2006

manner the monitoring program can be pared down to focus efforts on those locations necessary to confirm compliance with MCP Response Action Performance Standards for a Permanent Solution. Groundwater monitoring will be terminated after achievement of a Permanent Solution as a Class A-3 RAO for the entire site.

The list of wells to be sampled for tritium will be re-evaluated based on the results of the quarterly sampling proposed in the GMP-LTP. Wells could be added to, or removed from, the above list of locations targeted for monitoring based on the criteria outlined above. In addition, a more frequent sampling program may be implemented if deemed appropriate to facilitate site closure using the above criteria (i.e., sampling rounds could be conducted annually, semi-annually or, at a minimum frequency, quarterly).

4.2 OHM GROUNDWATER MONITORING PLAN Groundwater sampling and analysis of OHM parameters will be conducted in the Fall of 2006 at select monitoring well locations (Table 3 and Figure 2). The groundwater sampling event will focus on monitoring wells that have previously exceeded RCGW-1 Standards. Additionally, sampling will be conducted at replacement monitoring well locations that historically exceeded RCGW-1 Standards and were abandoned during decommissioning activities.

Analytical results from the Spring and Fall 2006 groundwater monitoring events will be evaluated to determine the need for future sampling.

Groundwater monitoring will be conducted at select monitoring wells that continue to exceed RCGW-1 standards (or an alternative risk-based standard agreed to by YAEC and MA DEP). Monitoring will be conducted at least annually until the levels of OHM in groundwater are below RCGW-1 standards for two consecutive rounds at each individual well. As with the radiological sampling, a more frequent sampling program may be implemented if deemed appropriate to facilitate site closure using the above criteria (i.e., sampling could be conducted annually, semi-annually or quarterly).

Sampling proposed in Table 3 will be conducted in accordance with YAEC standard operating procedures and the Quality Assurance Project Plan, Site Closure, Revision 2, Yankee Nuclear Power Station, Rowe, Massachusetts, Gradient, 20 December 2005. The following Quality Assurance / Quality Control (QA/QC) samples will be collected during groundwater sampling activities for OHM parameters:

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• Trip Blanks - One trip blank set for every 20 VOC, Alcohol or VPH samples or one trip blank set in every cooler used to ship VOC, Alcohol or VPH samples, whichever number is greater. Each VOA vial trip blank is filled with an aliquot of deionized water and sealed with Teflon septa. The trip blanks should be prepared and provided by the analytical laboratory.

• Temperature Blanks - One temperature blank per cooler. The temperature of the temperature blank will be measured upon receipt of the cooler at the laboratory.

• Equipment Rinsate Blank - The majority of groundwater samples will be collected using dedicated sampling equipment. However, where the depth to water is greater than 30 feet, a submersible pump will be used. A rinsate sample will be collected from the pump at a rate of one sample per 20 sampling locations. The rinsate blanks will be analyzed for the same parameters as the samples that were collected using the equipment.

Field Duplicates - Field duplicates will be collected at the rate of one duplicate per 20 samples. Field duplicates will be submitted for the same analyses as the parent sample. Field duplicates should be submitted "blind" to the analytical laboratory.

• Matrix Spikes - Matrix spikes will be collected at the rate of one matrix spike and one matrix spike duplicate per 20 samples.

Matrix spikes/matrix spikes duplicates will be analyzed for the same analyses as the actual sample. The monitoring well location for matrix spikes and matrix spike duplicates are identified to the analytical laboratory.

4.3 WELL CLOSURES Monitoring wells that will not be included in the GMP-LTP or GMP-MCP will be decommissioned in-place within one year of termination of monitoring at each location.

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Tables

-m m-m-

m

-m m-m Table 2 Summary of Contaminants in Groundwater Yankee Nuclear Power Station Rowe, MA Monitoring Well ID Historic Results Greater than RCGW-1 Elevated Tritium MCP Groundwater Comment M Mo nitoring Comn CW-5R Yes Replacement well to evaluate downgradient of former fuel oil tank CW-10 bis(2-Ethylhexyl)phthalate Yes MW-6R Extractable Petroleum Hydrocarbons (C11-C22)

Yes Replacement well to evaluate historic EPH concentrations MW-101A arsenic X

Yes MW-101B Extractable Petroleum Hydrocarbons (Cll-C22)

Yes MW-101C Volatile Petroleum Hydrocarbons (C5-C8), acetone Yes MW-102D X

Yes MW-105B bis(2-Ethylhexyl) phthalate Yes MW-105C 1,1-Dichloroethylene, acetone Yes MW-106A X

Yes MW-107A arsenic and silver X

Yes MW-107B Polychlorinated Biphenyls Yes MW-107C pentachlorophenol X

Yes Subsequent sampling below RCGW-1 for pentachlorophenol MW-107D Polychlorinated Biphenyls X

Yes MW-107E X

Yes MW-107F X

Yes Not yet sampled for OHM MW-109B pentachlorophenol Yes MW-109C pentacldorophenol Yes MW-109D pentachlorophenol Yes MW-110A Yes Evaluate historic PCBs at MW-5 MW-110C 2-butanone (MEK)

Yes MW-111B 2-butanone (MEK)

Yes MW-111C X

Yes MW-112A Yes New well downgradient of solvent usage area Notes:

Non-Radiological Groundwater concentrations compared to Report Concentration (RCGW-1) standards Elevated Tritium = Greater than 5,000 pCi/ L based on a preliminary review of July 2006 data

-= sample results below RCGW-1 standards Page 1 of I

Table 3 MCP Groundwater Monitoring Parameters Yankee Nuclear Power Station Rowe, MA Analytical parameters OHM Well Designation Sample ID Status Tritium VOC SVOC ALCOHOL EPH VPH PP13 Metals plus Total PCBs Boron CW-5R CW-5R Proposed Replacement Well X

X X

CW-10 CW-10 Existing x

MW-6R MW-6R Proposed Replacement Well X

X MW-101A MW-101A Existing x

MW-101B MW-101B Existing X

MW-101C MW-1O0C Existing x

X x

MW-102D MW-102D Existing x

MW-105B MW-105B Existing X

MW-105C MW-105C Existing x

X MW-106A MW-106A Existing X

MW-107A MW-107A Existing X

X MW-107B MW-107B Existing X

MW-107C M W-107C Existing X

MW-107D MW-l071)

Existing X

X MW-107E MW-107E Existing X

MW-107F MW-107F Existing X

x X

MW-109B MW-109B Existing X

MW-109C MW-109C Existing X

MW-109D MW-109D Existing X

MW-I10A MW-1IIA Existing x

MW-110C MW-110C Existing X

MW-111B MW-111B Existing X

MW-111C MW-111C Existing x

MW-112A MW-112A Proposed New Well Xx Total Original Samples:

Total Duplicate Samples:

Notes:

X' To be analyzed with Tentatively Identified Compounds (TICs) 9 8

1 S

1 1

3 1

3 4

1 3

Page 1 of 1

Figures

I

~~if MS ppp.

v/I i/I

/

ii:i Iii

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i.4

~~--

YAEC~RoertyBoijnd"r Scale 1 25,000 0.5km 0

500m 0.5 mi 0

1,000 ft Figure 1 Locus Map Yankee Nuclear Power Station -Rowe, MA ERM

Appendix B Tritium Risk-Based Concentration in Drinking Water

Attachment B Tritium Risk-Based Concentration in Drinking Water The attached table presents that risk-based concentration (RBC) for tritium in drinking water. The calculation adopts Mass DEP default exposure assumptions for child and adult drinking water consumption over a total exposure duration of 30 years. The calculations adjust for inherent radioactive decay of tritium (half-life = 12 years). As shown in the table, a 10-5 RBC for drinking water is 23,060 pCi/L, which is consistent with the EPA and Mass DEP drinking water criteria of 20,000 pCi/L.

The average concentration over the child (0 - 6 years) and adult (6 - 24 years) was calculated following the methods in Section 4.2.2 of the January 2005 YAEC Human Health Risk Assessment Work Plan (Draft), excerpted below without modification for ease of reference.

YAECGroundwatcrMonitoringDEP Attachment B.doc I

Gradient CORPORATION

January 2005 YAEC Human Health Risk Assessment Work Plan (Draft) - Excerpt 4.2.2 Exposure Quantification for Radionuclides Potential exposure to radionuclides is calculated in terms of radioactivity (in pico-curies, or "pCi") rather than in chemical mass units. Exposures via ingestion and inhalation pathways are calculated using similar approaches to those just described for chemical exposure, simply expressing exposure as the total amount of radioactivity (pCi) received over a particular duration. In the equations below, the radiation exposure is expressed in terms of an "intake factor."

The intake factor accounts for either ingestion (e.g., soil, water, food) or inhalation. Radiation intake for these pathways is given by (USEPA, 2000):'

IF

=

EPC x IR x EF x ED (4-4) where:

IF

=

Intake factor (pCi)

EPC

=

Exposure point concentration (e.g., pCi/g, pCi/m3, pCi/L)

IR

=

Media intake rate (e.g., g/day, m3/day, L/day)

EF

=

Exposure frequency (days/year)

ED

=

Exposure duration (years)

As can be seen by comparing Equation (4-1) and (4-4), the intake factor for radionuclides is a function of exposure duration and exposure frequency. The media intake rates, exposure frequency and duration for radionuclide intake are identical to those for the chemical exposure estimates, and are provided in Table 2.

The concentration of radionuclides in the environment declines according to radionuclide-specific decay rates. Thus, the EPC is not a constant, but rather declines as a function of time according to the following exponential equation:

EPC(t) =

EPCo e-"

(4-5) where EPC(t) =

concentration as a function of time (pCi/g)

The equations presented by USEPA (2000) are for a "risk-based" concentration in soil, air, water, etc. The intake is given by simply rearranging those equations such that they are expressed as a "risk equation" without substituting a "target risk" value.

YAECGro,,dwaterMonitoringDEPAttachment B.doc 2

Gradient CORPORAMN

EPCo

=

initial concentration at time t=0 (pCi/g) k h1(2) is the decay constant (per year) t1/2 t

=

half-life (years)

The average concentration ( EPC ) over a particular time period (T) is given by integrating the declining concentration over the time period:

EPC

=

JEPCoe_*dt To (4-6)

(1 - e-T )

EPC0 T)

TA In the above equation, the time period "T" is equivalent to the exposure duration (ED) in Equation (4-4).

Thus, combining the expression for the average concentration for EPC in Equation (4-6) with the intake factor expression in Equation 4-4), gives the following decay-adjusted intake factor IF

=

EPCO A

x IR x EF (4-7) where EPCo is the exposure point concentration at the beginning (time t=0) of the exposure period.

YAEC-GroundwaterMonitoringDEPA ttachment B.doc 3

Gradient CORPORATION

-rinkig Wmme m

s-B

-cti D

-t mu m

-ia Tritium Drinking Water Risk-Based Concentration Determination Chemicals Concentration Hlalf-Life Cadj Cadj Slope Factor DCF Ing Cancer Risk Dose (mremlyr)

Evaluated (C) t112 child adult (SF)

(CadjxlFxSF)

RBC RBC (dose)

I(pCi/L)

(yrs)

(pCi/L)

(pCi/L)

(Risk/pCi)

(mrem/pCi) 1.00E-05 4

Tritiun 23,000 12.0 19,437.6 8,798.7 5.07E-14 6.40E-08 9.97E-06 0.87 23,060 106,342 (p~iL) yrs (pi/L)

(pCIL)

(Rik/p~)

(remp~i l.0E-0 Totall L.OE-05 1

0.9 Intake Factor (IF -- adult IR x FS x EF x ED

=

1.75E+04 IF (dose) = IR x FS x EF =

7.30E+02 Intake Factor (IF -- child IR x FS x EF x ED

=

2.19E+03 IF (dose) = IR x FS x EF =

3.65E+02 IR Ingestion Rate--adult (Lday) 2 ED Exposure Duration--adult (yr) 24 IR Ingestion Rate -- child (L/day)

I ED Exposure Duration - child (yr) 6 EF Exposure Frequency (d/yr) 365 FS Fraction from Contaminated Source I

Notes:

Cadj is the decay-adjusted concentration over the exposure period based on the radionuclide decay half-life.

Slope Factor source: IIEAST Ri*_R.d.XLS4XWAingWaia tritim Page I of I Gradient CORPORATION