ML11214A192

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North Plateau Permeable Treatment Wall Performance Monitoring Plan
ML11214A192
Person / Time
Site: West Valley Demonstration Project, P00M-032
Issue date: 03/15/2011
From: Michalczak L
West Valley Environmental Services
To:
NRC/FSME
References
WVDP-512, Rev. 1
Download: ML11214A192 (102)
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VERIFY HARD COPY AGAINST WEB SITE IMMEDIATELY PRIOR TO EACH USE West Valley Doc. ID Number WVDP-512 Revision Number Rev. 1 Demonstration Project Revision Date 03/15/2011 NORTH PLATEAU PERMEABLE TREATMENT WALL PERFORMANCE MONITORING PLAN Cognizant Author: Linda M. Michalczak Quality Assurance: Howard L. Payne Cognizant Manager: Charles A. Biedermann West Valley Environmental Services LLC 10282 Rock Springs Road West Valley, New York USA 14171-9799 WV-1816, Rev. 6

WVDP-512 Rev. 1 TABLE OF CONTENTS

1.0 INTRODUCTION

.............................................................................................................................. 1

2.0 BACKGROUND

............................................................................................................................... 1 2.1 SUBSURFACE DESCRIPTION.......................................................................................... 1 2.2 PTW DESIGN AND INSTALLATION .................................................................................. 2 3.0 PERFORMANCE MONITORING OBJECTIVES ............................................................................. 2 4.0 PERFORMANCE MONITORING NETWORK ................................................................................. 3 4.1 PERFORMANCE MONITORING LOCATIONS.................................................................. 3 4.2 MONITORING WELL CONSTRUCTION AND DEVELOPMENT....................................... 5 4.2.1 MONITORING WELL CONSTRUCTION WITHIN PTW........................................ 5 4.2.2 MONITORING WELL CONSTRUCTION OUTSIDE PTW..................................... 5 4.2.3 MONITORING WELL DEVELOPMENT AND SURVEYING.................................. 6 5.0 PERFORMANCE MONITORING..................................................................................................... 6 5.1 VISUAL INSPECTIONS......................................................................................... 6 5.2 HYDRAULIC MONITORING.................................................................................. 7 5.3 GROUNDWATER QUALITY MONITORING ......................................................... 8 6.0 PERFORMANCE MONITORING EVENTS ..................................................................................... 9 6.1 BASELINE MONITORING ................................................................................... 11 6.2 ROUTINE MONITORING .................................................................................... 12 6.3 SUPPLEMENTAL HYDRAULIC MONITORING.................................................. 13 6.4 ANNUAL MONITORING ...................................................................................... 13 6.5 5-YEAR COMPREHENSIVE MONITORING ....................................................... 13 6.6 SUPPLEMENTAL CHARACTERIZATION .......................................................... 13 7.0 DATA ANALYSIS AND REPORTING............................................................................................ 14

8.0 REFERENCES

............................................................................................................................. 15

WVDP-512 Rev. 1 TABLE OF CONTENTS (CONTINUED)

TABLES / FIGURES / ATTACHMENTS Table 1A - PTW Performance Monitoring Network Monitoring Wells Installed After PTW Construction... 16 Table 1B - PTW Performance Monitoring Network - Pre-Existing Monitoring Wells ................................ 18 Table 2 - Performance Monitoring Activities .............................................................................................. 19 Table 3 - Evaluation of Functional Requirements ...................................................................................... 20 Figure 1 - Site Location .............................................................................................................................. 22 Figure 2 - Site Features.............................................................................................................................. 23 Figure 3 Distribution of Sr-90 in Sand and Gravel Unit............................................................................... 24 Figure 4 - PTW Alignment .......................................................................................................................... 25 Figure 5 - February 2010 Soil Boring Locations......................................................................................... 26 Figure 6 - February 2010 Investigation Results ......................................................................................... 27 Figure 7 - Existing North Plateau Monitoring Network ............................................................................... 28 Figure 8 - New PTW Performance Monitoring Wells ................................................................................. 29 Attachment A - Example PTW Inspection Form......................................................................................... 30 Attachment B - Well Construction Diagrams for Wells Installed in December 2010.................................. 32

WVDP-512 Rev. 1 Page 1 of 98

1.0 INTRODUCTION

West Valley Environmental Services, LLC (WVES) was directed by the U.S. Department of Energy to mitigate the spread of Strontium-90 (Sr-90) affected groundwater beneath the North Plateau at the West Valley Demonstration Project located in West Valley, New York (Figure 1; Figure 2) A permeable treatment wall (PTW) was selected to mitigate the migration of Sr-90 affected groundwater along an alignment located north of the main plant facility and hydraulically downgradient of the area of greatest groundwater impact. This Performance Monitoring Plan (Plan) outlines a monitoring program that will be used to evaluate the effectiveness of the PTW. This Plan meets the requirements of the Summary Design Criteria for the PTW that require the preparation of a monitoring plan that addresses the placement of wells, plans for sampling and analysis of groundwater, and provides methods to evaluate the data to determine performance of the PTW. Any monitoring plan for the PTW will be implemented fully consistent with the administrative and programmatic procedures set forth in WVDP-091-Groundwater Protection Management Program Plan, WVDP-239-Groundwater Monitoring Plan, and WVDP-190-Groundwater Monitoring Equipment Decommissioning Plan.

This Plan consists of eight sections and attachments. Section 2.0 includes background information pertaining to site hydrogeology, the distribution of Sr-90 in groundwater, the PTW design, and the installation of the PTW; Section 3.0 of the Plan identifies performance monitoring objectives; Section 4.0 describes the performance monitoring network; performance monitoring activities are detailed in Section 5.0; a monitoring schedule and activities for the various monitoring events is described in Section 6.0; Section 7.0 includes data analysis and reporting; and Section 8 includes a list of references.

2.0 BACKGROUND

2.1 Subsurface Description Sr-90 affected groundwater on the North Plateau migrates generally in a northerly direction through surficial sand and gravel deposits that overlay the surface of a laterally extensive till unit (Lavery till or ULT). The surficial sand and gravel deposits are further subdivided into a thick-bedded unit (TBU) and a slack-water sequence (SWS). The TBU is a postglacial alluvial fan and the more extensive of the two deposits. The SWS is a glacial melt water deposit that contains thin-bedded layers of clay, silt, sand, and fine-grained gravel. The TBU overlies the Lavery till over most of the North Plateau and directly overlaps the older SWS that occurs in a narrow northeast-trending trough in the Lavery till (AMEC, 2009).

The lateral extent of Sr-90 affected groundwater on the North Plateau is coincident with the lateral extents of the SWS south of Lagoon 5. Near Lagoon 5, the Sr-90 plume splits into three lobes. These lobes have previously been referred to as the western, central, and eastern lobe (Figure 3). The leading edge of the western lobe migrates toward the swamp ditch.

WVDP-512 Rev. 1 Page 2 of 98 The leading edge of the recently identified center lobe extends to the central portion of the Construction and Demolition Debris Landfill (CDDL) along the orientation of the SWS.

The leading edge of the eastern lobe occurs north of Lagoon 3 and southeast of the CDDL (Figure 3).

2.2 PTW Design and Installation The groundwater remediation system selected to mitigate the migration of Sr-90 affected groundwater consists of an approximately 860-foot long hydraulically passive permeable treatment wall of granular zeolite. The alignment selected for the PTW is located north of the main plant facility and hydraulically downgradient of the area of greatest groundwater impact (Figure 4). The PTW intersects both the TBU and SWS, and is keyed into the underlying ULT with the intent of fully capturing the vertical extent of Sr-90 affected groundwater. The functionality of the PTW system is based on the capacity of the zeolite to preferentially sorb Sr-90 cations, displacing other cations on the molecular structure of the mineral through an ion exchange process. Although Sr-90 (a divalent cation) in site groundwater will be exchanged for monovalent cations (such as sodium and potassium) within the zeolite structure, naturally occurring divalent cations (such as calcium and magnesium) also will compete for these sites. Additional details related to the PTW design are included in the West Valley Thirty Percent Design Report - North Plateau Permeable Treatment Wall (AMEC, 2009).

A detailed soil boring program was completed in February 2010 along the proposed PTW alignment. The program included the advancement of 39 soil borings to ULT surface.

Soils were field screened for radioactivity using a Geiger Muller unit. Temporary well screens were used to collect groundwater samples that were subsequently analyzed for Sr-90. Soil boring locations are depicted in Figure 5. The results of this investigation, including geologic interpretation, Geiger counter readings, and groundwater sampling results are summarized in cross section view in Figure 6.

The PTW was installed in October/November 2010 (cap completed November 28, 2010) with details provided in the associated Installation Report scheduled for issuance as WVDP-521 by June 2011.

3.0 PERFORMANCE MONITORING OBJECTIVES The general objectives of the performance monitoring program will be to:

1. Monitor the physical integrity of the PTW and its components.
2. Assess the movement of Sr-90 affected groundwater in the vicinity of the PTW.
3. Monitor and assess the removal of Sr-90 from groundwater moving through the PTW.

WVDP-512 Rev. 1 Page 3 of 98 The overall objective of the performance monitoring program will be to evaluate whether the functional requirements for the PTW are being met. Eight functional requirements were developed for the PTW based on the Remedial Action Objectives for the site (AMEC, 2009). The functional requirements are:

1. Create a sorption barrier (PTW) that limits the expansion of groundwater impacted by Sr-90 at or above the 10,000 pCi/L level. Due to constructability issues, the PTW will not be designed to address groundwater impacted at or above the 10,000 pCi/L level that has migrated below and west of the Construction and Demolition Debris Landfill.
2. Sr-90 contamination levels in groundwater passing through the PTW should demonstrate an overall stable or downward trend (compared to upgradient levels) over time to support an objective of substantially reducing plume expansion.
3. Sr-90 contamination should not be redirected to currently less-contaminated areas.
4. Groundwater flow through the PTW should be sufficient to preclude substantial changes in groundwater flow patterns that would require additional mitigation actions.
5. The PTW shall be keyed into the underlying competent aquitard (unweathered Lavery till unit) a minimum of one foot along the PTW alignment.
6. Groundwater monitoring shall be maintained around the PTW. Proposed modifications to the existing monitoring network will be evaluated and approved by Environmental Affairs.
7. Design should not preclude any strategies for further addressing Sr-90 plume during decommissioning.
8. Expended PTW material (e.g., zeolite) must be able to be removed if required in the future.

Functional Requirement 1, 2, 3, and 4 can be evaluated using the performance monitoring program identified in this document. Functional Requirement 5, 7, and 8 are addressed through the PTW design process and quality assurance/quality control during PTW construction.

Functional Requirement 6 is addressed by implementation of a performance monitoring program similar to the one detailed in this Plan. After the performance monitoring program and associated data analysis are described in greater detail in Section 6.0 and 7.0, individual components of the performance monitoring program are related back to one or more of the functional requirements to describe in greater detail how performance monitoring will be used to evaluate functional requirements for the PTW.

4.0 PERFORMANCE MONITORING NETWORK 4.1 Performance Monitoring Locations The PTW performance monitoring system consists of a network of existing groundwater monitoring wells, and new wells that were installed as part of the PTW implementation program. The existing monitoring network for the North Plateau Sr-90 plume is shown in Figure 7.

WVDP-512 Rev. 1 Page 4 of 98 A subset of monitoring wells from the existing plume monitoring network has been incorporated into this Plan to assess the movement of Sr-90 impacted groundwater in the vicinity of the PTW. Monitoring wells in each of the three plume lobes are incorporated into the Plan.

Additional wells are incorporated into the Plan to monitor groundwater conditions between the three plume lobes. These wells are identified in Figure 7. [Note: Although not part of PTW performance monitoring, pursuant to WVDP-518, North Plateau Groundwater Monitoring Plan, another subset of wells from the existing plume network are monitored for gross beta and water levels to evaluate plume migration.]

Sixty-six new wells, comprised primarily of twelve monitoring stations, were installed on the PTW installation platform in December 2010 to supplement existing wells. Each station consists of three monitoring locations installed as a transect oriented perpendicular to the PTW alignment. Monitoring locations are installed at the southern edge of the installation platform to assess influent groundwater conditions; within the PTW to assess groundwater conditions inside of the PTW; and at the northern edge of the installation platform to assess presumed effluent groundwater conditions. Monitoring stations were installed within each of the three Sr-90 plume lobes to monitor segments of the wall that are expected to experience comparatively larger Sr-90 loading. Additional stations were also installed between the plume lobes. Monitoring wells were also installed near the two ends of the PTW to monitor for changes in groundwater flow in these areas.

Monitoring wells are depicted in Figure 8.

Monitoring locations where both the SWS and TBU are present were installed as well couplets consisting of collocated wells screened in each respective unit. Well couplets were also installed in portions of the wall characterized by larger saturated thicknesses.

Well couplets will provide additional information regarding vertical gradients and the vertical distribution of Sr-90. Well couplet locations are depicted in Figure 8.

Well clusters, consisting of four (4) collocated small-diameter monitoring wells, were installed at two locations within the PTW. The screened intervals of the cluster wells were positioned vertically to provide higher resolution information regarding vertical gradients within the PTW. Cluster well locations are depicted in Figure 8.

The single pass trenching machine that installed the PTW could not vary the installation depth of the PTW at a rate (or slope) equal to the elevation changes in the till surface.

The trenching machine was required to trench through a number of small hills in the till unit to ensure that the PTW is adequately keyed into the underlying till. Five small higher elevation areas in the till unit (till hills) were trenched through. Trenches of higher permeability material (i.e., zeolite) present in the till hills could potentially create a conduit for lateral flow within the PTW. Alternatively, these higher permeability trenches in the till hills could function as stagnation zones with little to no lateral flow.

WVDP-512 Rev. 1 Page 5 of 98 Monitoring wells were installed within the PTW at locations where the PTW intersected a till hill to evaluate the potential for lateral groundwater flow. Local velocities in the vicinity of these wells will be evaluated using the techniques described below in Section 5.2.

Depending on the results of hydraulic testing (that is, if substantial lateral flow was occurring), these wells will be incorporated into routine sampling events. Conversely, if hydraulic testing indicated the higher permeability trenches through the till hills were functioning as stagnation zones, then the wells will remain in place but not be incorporated into routine sampling events. By remaining in place, the wells could be used for specialty or contingency monitoring at a later date if appropriate.

Newly installed monitoring wells on the PTW installation platform are collectively referred to in this Plan as PTW wells. The entire performance monitoring network, which consists of newly installed wells on the PTW installation platform (Table 1A) and existing monitoring wells (Table 1B) will be referred to as full network .

4.2 Monitoring Well Construction and Development 4.2.1 Monitoring Well Construction within PTW The permeability of the zeolite treatment media is expected to be greater than the permeability of sand sizes typically used in the construction of filter packs.

Therefore, well assemblies without preinstalled filter packs were used for monitoring wells installed within the PTW (intra-wall wells) whereas the zeolite treatment media was allowed to naturally collapse around the well. In wells that zeolite collapse was not realized, zeolite [or sand (Well S12B)] was placed into the void space. Well assemblies for intra-wall wells consist of 2.0-inch diameter Schedule 40 PVC with 0.020-inch slot size. A slightly larger slot size was selected for the intra-wall wells to account for the greater permeability of the zeolite treatment media. Well screen lengths were either 5-feet or 10-feet depending on the thickness of the TBU or SWS at each location. The well assembly for the two well clusters used to monitor vertical gradients within the PTW consists of 1.0-inch diameter Schedule 40 PVC with 0.020-inch slot size.

Well screen lengths are 3-feet.

Well construction logs are provided in Attachment B.

4.2.2 Monitoring Well Construction Outside PTW The well assemblies for wells installed outside of the PTW consist of 1.5-inch diameter Schedule 40 PVC with factory installed 0.7-inch filter packs. The factory prepared filter pack consists of 20/40 sand wrapped in a stainless steel mesh.

Well screen lengths are either 5-feet or 10-feet depending on the thickness of the TBU or SWS at each location. The slot size for the well screens is 0.010-inches.

Well construction logs are provided in Attachment B.

WVDP-512 Rev. 1 Page 6 of 98 4.2.3 Monitoring Well Development and Surveying Monitoring wells were developed in January 2011 in accordance with EM-519 -

Monitoring Well Development. Following installation, monitoring wells were surveyed by a State of New York licensed surveyor. Surveyed well attributes include northing and easting in the State Plane coordinate system along with the elevation of ground surface, and the top of the PVC riser pipe.

5.0 PERFORMANCE MONITORING Performance monitoring for the PTW will consist of three components:

1. Visual inspections to monitor the physical integrity of the PTW and its components.
2. Hydraulic monitoring to assess the movement of Sr-90 affected groundwater in the vicinity of the PTW.
3. Groundwater quality monitoring to assess the treatment performance of the PTW.

5.1 Visual Inspections Within 3 months of PTW installation or as soon as the snow-pack that developed immediately after PTW cap completion melts, baseline visual conditions will be documented (photographs, etc.) to provide the basis for the following subsequent visual inspections.

Visual inspections of the PTW area will be conducted during quarterly/annual monitoring events. The objective of site inspections is to detect changes in ground surface, land use, construction, etc., that may indicate a physical change in the PTW.

During each monitoring event, a visual inspection of the ground surface along the PTW alignment will be performed. If changes in the ground surface are observed, such as local depressions or mounds, the location and description of the feature(s) will be documented and reported. New landscaping, utilities, or any other physical or operational changes that could potentially affect the physical integrity of the PTW will also be reported. Visual inspections will also evaluate potential seepage faces that could be indicative of groundwater discharging to land surfaces in the vicinity of the PTW. If groundwater seepage to land surface is identified, a surface water sample will be collected and submitted for laboratory analysis of Sr-90.

Visual inspections of storm water infrastructure in the vicinity of the PTW will also be conducted during PTW performance monitoring events. The objective of the visual inspections is to identify damage to the drainage network or physical obstructions within the drainage network that could potentially lead to increased storm water infiltration in the vicinity of the PTW. Visual inspections will evaluate the following:

  • Debris that may have collected in the drainage channel(s) and is potentially restricting flow.

WVDP-512 Rev. 1 Page 7 of 98

  • Debris that may have collected at entrances to catch basins and may be restricting flow.

Debris that has collected in the drainage swale or at catch basin inlets will be removed, if practical, in conjunction with the visual inspection. If debris cannot be removed upon identification then the debris will be noted on the PTW inspection form and flagged for follow up action.

Erosional channels, depressions, or other surface features identified during the inspection that could potentially lead to increased infiltration in the vicinity of the PTW will be filled and graded as appropriate.

Inspection results and any repairs or maintenance conducted as a result of inspections will be documented in PTW performance monitoring reports. PTW performance monitoring reports will be prepared annually in conjunction with the groundwater monitoring reports that are currently prepared for the site. [Note: For data generated during the baseline and first quarter monitoring events, DOE requested that separate reports be prepared versus reporting of data in annual monitoring reports.]

A copy of an example PTW Inspection Form has been included as Attachment A.

5.2 Hydraulic Monitoring Hydraulic monitoring activities are summarized below. Additional details regarding the frequency and locations (i.e., which monitoring wells) of these activities, and data analysis methods, are provided in the following sections.

  • Water Level Measurements - Depth to groundwater measurements will be collected with a water level meter during sampling events. For the first year of PTW system (i.e., CY 2011) operation, water level measurements will be measured on a monthly basis. Water level measurements will be collected in accordance with EM-6 Groundwater Sampling.
  • In Situ Hydraulic Conductivity Testing - In situ hydraulic testing will be conducted to estimate hydraulic conductivities (e.g., permeability changes) within and in the vicinity of the PTW. On select performance monitoring wells in situ hydraulic conductivity testing will be conducted in accordance with EMP-521, In Situ Hydraulic Conductivity Testing.
  • Well Tracer Dilution Tests - Well tracer dilution tests (i.e., dilution tests) will be conducted to estimate localized velocities in the vicinity of each monitoring well.

Dilution tests provide a direct measurement of groundwater flow rates within a single well without the need to estimate hydraulic conductivities or gradients (Hall, 1993; Halevy et al., 1967). During the dilution test, groundwater within the well (the test interval) is continuously mixed by extracting and reinjecting groundwater with a peristaltic pump. A concentrated sodium bromide solution (or other tracer) is slowly

WVDP-512 Rev. 1 Page 8 of 98 metered into the recirculating groundwater to establish an initial dissolved bromide concentration between 200 and 500 milligrams/liter in the test interval. After the bromide tracer has been introduced to the test interval, changes in bromide concentrations are monitored over time using a hand-held ion specific electrode.

The rate at which the tracer concentration decreases in the test interval is a function of the flow through the well and can be used to estimate groundwater velocity.

Tracer dilution tests will be conducted in accordance with EMP-63, Well Tracer Dilution Tests.

  • Pressure Transducer Monitoring - Pressure transducers will be installed in a subset of wells located within the PTW during the first year of PTW system operation to monitor hydraulic responses to rainfall events and snowmelt. The transducers will both measure and record hydraulic pressure changes at a regular interval (e.g.,

seconds, minutes, hours) defined by the user. The transducers, recorder, and its power supply (internal battery) are installed completely within the well with data downloaded to a portable computer as needed. After installation, the transducers will be calibrated against hand measurements using a water level meter. After the initial calibration the transducers will be checked again daily for the first week and then weekly for the remainder of the first month. Data will be downloaded from the transducers on a monthly basis.

5.3 Groundwater Quality Monitoring Groundwater quality monitoring activities are summarized below. Additional details regarding the frequency and locations (i.e., which monitoring wells) of these activities, and data analysis methods, are provided in the following sections.

  • Strontium-90 Sampling - Groundwater sample collection from performance monitoring wells and subsequent laboratory analysis for Sr-90.
  • Geochemical Sampling - Groundwater sample collection from the performance monitoring wells and subsequent laboratory analysis for major cations and anions (sodium, potassium, calcium, magnesium, carbonate, bicarbonate, sulfate, and chloride).
  • Field Parameters - Standard field parameters will be measured during groundwater sampling with flow through cells or other field instruments and include temperature, pH, oxidation-reduction potential, specific conductance, dissolved oxygen, and turbidity. [Although these parameters are not directly related to monitoring the performance of the PTW, results will be utilized to identify overall conditions in the groundwater. Changes to such conditions may occur during future site decommissioning activities (e.g., upgradient excavations, etc.).]

WVDP-512 Rev. 1 Page 9 of 98 All groundwater sampling activities will be conducted in accordance with EM-6 Groundwater Sampling and EM-52 Environmental Sample Receipt, Handling, Storage, Packaging, and Shipment.

6.0 PERFORMANCE MONITORING EVENTS Performance monitoring events consist of:

  • initial baseline monitoring,
  • routine monitoring,
  • supplemental hydraulic monitoring
  • annual monitoring, and
  • 5-year comprehensive monitoring.

The initial baseline monitoring will be a comprehensive baseline evaluation of hydraulics and groundwater chemistry within and adjacent to the PTW. The initial monitoring event will generate baseline hydraulic and chemistry data that subsequent monitoring data will be compared against.

Routine monitoring events will be conducted over the operational lifetime of the PTW and consist primarily of water level measurements and sampling for Sr-90 in PTW wells.

Routine monitoring events will be completed on a quarterly basis during the first two years of PTW system operation (i.e., CY 2011 and 2012). A reduced monitoring frequency could potentially be proposed after the first two years of quarterly monitoring if monitoring data indicates temporal variability can be adequately captured using a reduced monitoring frequency (e.g. semi-annual instead of quarterly). Any proposed reduction in monitoring frequency will be submitted to DOE for approval prior to implementation.

Additional hydraulic monitoring will be conducted during the first year of PTW operation (i.e., CY 2011). This additional hydraulic monitoring will consist of water level measurements collected on a monthly basis.

One routine monitoring event per year will be replaced by the annual monitoring event regularly conducted by WVES at the site. The annual monitoring event will include water level measurements and groundwater sampling of the full monitoring network, and laboratory analysis for Sr-90 and geochemical constituents.

Every five years a comprehensive monitoring event will be completed (e.g., January 2016, 2021, 2026). The comprehensive monitoring event will replicate the initial baseline monitoring event and include more comprehensive hydraulic and groundwater monitoring as described in Section 6.5.

Additional details related to the identified monitoring events are included in the following sections.

The monitoring schedule is summarized below. A summary of the performance monitoring activities associated with each monitoring event is included in Table 2.

WVDP-512 Rev. 1 Page 10 of 98 Performance Monitoring Schedule Monitoring Event Frequency Initial Baseline Monitoring Completed once following PTW Installation.

1 Routine Monitoring Year 1 - Year 2 (CY 2011 & 2012): Quarterly Year 3 - Year 20: (CY 2013 - 2031)Potential reduced frequency depending on temporal variability of quarterly data collected in Year 1 -

Year 2.

Supplemental Hydraulic Monitoring Year 1 (CY 2011): Monthly 2

Annual Monitoring Annually Comprehensive 5-Year Monitoring Once every five years Notes:

1. Routine monitoring event replaced by annual monitoring event once per year.
2. Annual monitoring event replaced by comprehensive monitoring once every five years.

WVDP-512 Rev. 1 Page 11 of 98 6.1 Baseline Monitoring The initial baseline monitoring will be a comprehensive baseline evaluation of hydraulics and groundwater chemistry in the PTW area and within the PTW itself.

The baseline monitoring event will be conducted within three months of PTW installation and will consist of the following:

  • Water level measurements - full network.
  • In situ hydraulic conductivity testing (slug testing) - Slug testing will be performed at the 24 monitoring wells identified below. These wells include locations along the alignment of the PTW and at variable depths upgradient, within, and downgradient of the treatment wall. This will allow for evaluation of spatial and vertical variability in hydraulic conductivity results. Previous investigations have shown that hydraulic conductivity values within the plume can vary by one or more orders of magnitude. In-situ hydraulic conductivity tests will be performed at wells situated within each of the three lobes of the plume, as represented by previous Sr-90 contours. Areas with higher Sr-90 levels generally also have higher conductivities. Hydraulic conductivity tests will also be performed in wells in lower conductivity areas. Several well couplets with shallow and deep wells will also be tested to assess hydraulic conductivities in different horizons within the plume, including the lower slack water sequence present within the central portion of the plume.
  • Well tracer dilution tests (at 12 wells) - Dilution tests for intra-wall wells located at Station 1, 3 (both shallow and deep), 5 (both shallow and deep), 9, and 11 (Figure 8). The borehole dilution tests will provide additional information about groundwater flow velocities in the PTW. Stations 3, 5, and 9 are located in the three Sr-90 plume lobes (Figure 8). Station 1 and Station 11 are located at the eastern and western ends of the PTW. Dilution tests will also be conducted for the five wells installed in the till hills to determine if these wells should be included in routine sampling events.
  • Intra-wall hydraulic monitoring - Pressure transducer installation for a subset of intra-wall wells will occur during the baseline monitoring event. Transducers will be installed and monitored for intra-wall wells located at Station 3 (shallow well only), Station 5, and Station 9 (Figure 8). The transducers will remain in place for a period of one year to monitor hydraulic responses to rainfall events and snowmelt. Transducers will be temporarily removed during groundwater sampling events. Data will be downloaded on a monthly basis.
  • Sr-90 sampling - full network.
  • Geochemical sampling - full network.

WVDP-512 Rev. 1 Page 12 of 98 Slug Testing Wells Well ID Location Relative to PTW PTW-S3A-S Station 3, upgradient, shallow PTW-S3A-D Station 3, upgradient, deep PTW-S3C-S Station 3, downgradient, shallow PTW-S3C-D Station 3, downgradient, deep PTW-TH2 Till Hill east of Station 4, in PTW PTW-S5A-S Station 5, upgradient, shallow PTW-S5A-D Station 5, upgradient, deep PTW-S5B-S Station 5, in PTW, shallow PTW-S5B-D Station 5, in PTW, deep PTW-S5C-S Station 5, downgradient, shallow PTW-S5C-D Station 5, downgradient, deep PTW-S6A-S Station 6, upgradient, shallow PTW-S6A-D Station 6, upgradient, deep PTW-S6C-S Station 6, downgradient, shallow PTW-S6C-D Station 6, downgradient, deep PTW-S8A Station 8, upgradient PTW-S8B Station 8, in PTW PTW-S8C Station 8, downgradient PTW-S9A Station 9, upgradient PTW-S9B Station 9, in PTW PTW-S9C Station 9, downgradient PTW-S11A Station 11, upgradient PTW-S11C Station 11, downgradient PTW-E Far eastern end, outside of PTW 6.2 Routine Monitoring During the first two years of PTW operation (CY 2011 & 2012), routine monitoring will be conducted on a quarterly basis. Routine monitoring during the first year will include the following activities:

  • Water level measurements - PTW wells.
  • Sr-90 sampling - PTW wells.
  • Geochemical sampling - PTW wells.

Routine monitoring events occurring after the first year of performance monitoring will include the following activities:

  • Water level measurements - PTW wells.
  • Sr-90 sampling - PTW wells.

After the second year of monitoring (i.e., post CY 2012) a reduced monitoring frequency could potentially be proposed if monitoring data indicates temporal variability can be adequately captured using a reduced monitoring frequency (e.g. semi-annual instead of quarterly). Any proposed reduction in monitoring frequency will be submitted to DOE for approval prior to implementation.

WVDP-512 Rev. 1 Page 13 of 98 6.3 Supplemental Hydraulic Monitoring During the first year of PTW operation (CY 2011) additional water level measurements will be collected from the full network on a monthly basis. Water level measurements will be used to evaluate changes in the groundwater flow field that could potentially be attributable to installation of the PTW. Pressure transducer data will be downloaded during the monthly gauging events.

6.4 Annual Monitoring One routine monitoring event per year will be replaced with a more comprehensive annual monitoring event. The annual monitoring consist of the following activities:

  • Water level measurements - full network
  • Sr-90 sampling - full network.
  • Geochemical sampling - full network.

6.5 5-Year Comprehensive Monitoring Every five years the annual monitoring event will be replaced by a more comprehensive 5-year monitoring event. The comprehensive monitoring event will include all of the monitoring activities completed during the baseline evaluation with the exception of the pressure transducer study. The five year comprehensive event will also include a re-survey of performance monitoring wells situated with the PTW to account for potential elevation changes attributable to zeolite settling.

6.6 Supplemental Characterization The results of groundwater monitoring and hydraulic evaluation tests will be used to evaluate the effectiveness of the PTW in meeting the related functional requirements (i.e., Functional Requirements 1-4). If the results of the monitoring program indicate actual or potential unacceptable performance, additional measures will be implemented to: (1) verify the performance issue, (2) quantify the performance concern; and, if necessary, (3) develop mitigation measures designed to return the PTW to acceptable performance. The following paragraphs provide additional discussion on this topic.

Verification of potential unintended performance will be the first step in developing an appropriate contingency mitigation approach. Potential deficiencies in performance may be indicated by the analytical results of one or more groundwater samples from one or more groundwater monitoring locations exceeding water quality goals for the specific location. Although water level information also could be used to assess functionality of the PTW, water chemistry will be the primary parameter used to evaluate PTW performance. In this case, verification of results that exceed goals (i.e. Sr-90 activity values that exceed acceptable levels) will be performed after a potential exceedance is determined to be valid by the laboratory (that is, following successful review of quality assurance/quality control results for the sample(s) in question).

WVDP-512 Rev. 1 Page 14 of 98 The verification will consist of resampling the subject well(s) and chemically analyzing the data according to approved site methodology. If the new result does not show an exceedance of the water quality goal, then additional actions may not be necessary. If additional actions are not completed, future results from the well(s) of concern will be closely evaluated in future monitoring events.

Additional assessment, including potential additional characterization, will be performed to quantify the potential performance concern if the resampling confirms the water quality value exceedance. The additional work may include the following activities: (1) reviewing as-built construction information for potential structural conditions that may have influenced the results: (2) sampling additional adjacent well(s) to comprehensively evaluate the dimensions of the potential performance issue; (3) performing hydraulic tests - tracer and/or stress tests - to evaluate the groundwater/analyte flow patterns in the vicinity of the performance issue; (4) performing intrusive evaluation - boring or additional well placement - to comprehensively evaluate the subsurface conditions in and adjacent to the PTW in the area of concern. The specific measures to be used in this quantification characterization will be written in a work plan developed at the time of need, and subject to review by the DOE prior to implementation.

The results of the quantification characterization activities will be used to determine whether corrective action is necessary. Corrective action could consist of changes in the monitoring regime (e.g. more frequent monitoring, modifying the sampling parameter list, installing additional wells) and/or construction-based corrections including: reconfiguring the PTW in the area of under-performance by removing a portion of the PTW and replacing it, or adding additional lengths of the PTW up- or down-gradient from the underperforming PTW section. The underperforming PTW section could be abandoned and isolated (e.g. by grout injection) if such action will not detrimentally impact the performance of the remaining PTW. Before any such intrusive corrective action is attempted, a comprehensive design will be developed, reviewed, and vetted through the WVES design review process.

All actions related to the contingency mitigation approach will refer back to the PTW design basis as a guide to potential performance issues. This includes referring to both the laboratory tests performed by University of Buffalo and the engineering drawings used as the design basis.

7.0 DATA ANALYSIS AND REPORTING Results and data analysis generated from the performance monitoring program outlined in this Plan will be incorporated into existing annual groundwater reporting requirements for the site.

[Note: For data generated during the baseline and first quarter monitoring events, DOE requested that separate reports be prepared versus reporting of data in annual monitoring reports.]

Data analysis will include:

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  • Potentiometric surface maps - Water level measurements will be used to construct potentiometric surface maps. The potentiometric surface maps will be used to assess the movement of Sr-90 impacted groundwater in the vicinity of the PTW.
  • Vertical gradient analysis - Water level measurements from well couplets and cluster wells will be used to assess vertical gradients between the TBU and SWS and the potential for vertical flow within the PTW.
  • Sr-90 Plume Maps (plan view) - Maps depicting the lateral distribution of Sr-90 in the vicinity of the PTW will be developed from groundwater sampling results. Changes in the lateral distribution of Sr-90 will be used as one line of evidence to evaluate treatment of Sr-90 impacted groundwater.
  • Sr-90 Plume Maps (cross section view) - Cross sections will be constructed from influent, intra-wall, and effluent PTW wells. Comparison of Sr-90 distributions at influent, intra-wall, and effluent cross sections will be used as one line of evidence to evaluate treatment of Sr-90 impacted groundwater.
  • Geochemical Parameter Distribution Maps (plan view) - Maps depicting the lateral distribution of geochemical constituents in the vicinity of the PTW will be developed from groundwater sampling results. Because sorption of Sr-90 to the zeolite structure displaces various cations, comparison of changes in the lateral distribution of geochemical constituents will be used as a secondary line of evidence to evaluate treatment of Sr-90 impacted groundwater.
  • Geochemical Parameter Distribution Maps (cross section view) - Cross sections will be constructed from influent, intra-wall, and effluent PTW wells. Because sorption of Sr-90 to the zeolite structure displaces various cations, comparison of geochemical signatures at influent, intra-wall, and effluent cross sections will be used as a secondary line of evidence to evaluate treatment of Sr-90 impacted groundwater.
  • Hydraulic Testing Data Analysis - Data from slug tests, pressure transducers, and dilution tests will be analyzed to better understand the movement of Sr-90 impacted groundwater in the vicinity of the PTW.

A summary of the various types of data analysis identified in this Plan is included in Table 3.

8.0 REFERENCES

AMEC Geomatrix, Inc. (AMEC), 2009, West Valley 30% Design Report, North Plateau Permeable Treatment Wall, prepared for West Valley Environmental Services, LLC, October.

Halevy, E., Moser, H., Zellhofer, O., Zuber, A., 1967, Borehole dilution techniques: a critical review, in: Isotopes in Hydrology, IAEA, Vienna, p. 531-564.

Hall, S. H., 1993, Single-well tracer tests in aquifer characterization, Ground Water Monitoring and Remediation, 13:2, p. 118-124

WVDP-512 Rev. 1 Page 16 of 98 Table 1A PTW PERFORMANCE MONITORING NETWORK MONITORING WELLS INSTALLED AFTER PTW CONSTRUCTION North Plateau Permeable Treatment Wall West Valley Environmental Services, LLC West Valley, New York

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WVDP-512 Rev. 1 Page 18 of 98 Table 1B PTW PERFORMANCE MONITORING NETWORK PRE-EXISTING MONITORING WELLS North Plateau Permeable Treatment Wall West Valley Environmental Services, LLC West Valley, New York

WVDP-512 Rev. 1 Page 19 of 98 TABLE 2 PERFORMANCE MONITORING ACTIVITIES North Plateau Permeable Treatment Wall West Valley Environmental Services, LLC West Valley, New York Supplemental Routine Routine Hydraulic Initial Monitoring Monitoring Monitoring Comprehensive Baseline (year 1; CY (subsequent (year 1; CY Annual Monitoring Monitoring 2011) years) 2011)) Monitoring (every 5 years)

Visual Inspections x x x x x Well Surveying x x Hydraulic Monitoring Water Level Measurements - PTW Wells x x x x x Water Level Gauging - Full Network x x x x Slug Testing x x Well Tracer Dilution Tests x x 1

Pressure Transducer Tests x x Groundwater Quality Monitoring 4

Strontium-90 Sampling - PTW Wells x x 4

Strontium-90 Sampling - Full Network x x x 2 4 Geochemical Sampling - PTW Wells x 2 4 Geochemical Sampling - Full Network x x x 3

Field Parameters x x x x x Notes:

1. Pressure transducers will be installed in select monitoring wells during the first year of PTW operation to evaluate hydraulic effects of snowmelt and rainfall runoff.
2. Geochemical sampling will include sodium, potassium, calcium, magnesium, carbonate, bicarbonate, sulfate, and chloride.
3. Standard water quality measurements will be collected from each sampled well. Measurements will include temperature, pH, oxidation-reduction potential, specific conductance, dissolved oxygen, and turbidity.
4. Excluding the two sets of cluster wells installed to monitor vertical gradients (PTW-C1-TBU1 through 4; PTW-C2-TBU1 through 4).

WVDP-512 Rev. 1 Page 20 of 98 TABLE 3 EVALUATION OF FUNCTIONAL REQUIREMENTS North Plateau Permeable Treatment Wall West Valley Environmental Services, LLC West Valley, New York Functional Requirement Data Analysis

1. Create a sorption barrier (PTW) that limits the Sr-90 Plume Map (plan view). Maps depicting the lateral distribution of Sr-90 in the vicinity expansion of groundwater impacted by Sr-90 at of the PTW will be developed from groundwater sampling results. Plume maps used to or above the 10,000 pCi/L level. Due to monitor changes in the spatial distribution of Sr-90 at or above the 10,000 pCi/L level.

constructability issues, the PTW will not be Sr-90 Plume Maps (cross section view) - Cross sections will be constructed from influent, designed to address groundwater impacted at intra-well, and effluent PTW wells. Sr-90 distribution at effluent cross section used to or above the 10,000 pCi/L level that has evaluate concentrations at the presumed PTW effluent.

migrated below and west of the CDDL.

2. Sr-90 contamination levels in groundwater Sr-90 Plume Map (plan view). Maps depicting the lateral distribution of Sr-90 in the vicinity passing through the PTW should demonstrate of the PTW will be developed from groundwater sampling results. Changes in the lateral an overall stable or downward trend (compared distribution of Sr-90 will be used as one line of evidence to evaluate treatment of Sr-90 to upgradient levels) over time to support an impacted groundwater.

objective of substantially reducing plume expansion Sr-90 Plume Map (cross section view). Cross sections will be constructed from influent, intra-well, and effluent PTW wells. Comparison of Sr-90 distributions at influent, intra-wall, and effluent cross sections will be used as one line of evidence to evaluate treatment of Sr-90 impacted groundwater.

Geochemical Parameter Distribution Maps (plan view) - Maps depicting the lateral distribution of geochemical constituents in the vicinity of the PTW will be developed from groundwater sampling results. Because sorption of Sr-90 to the zeolite structure displaces monovalent cations (potassium, sodium) changes in the lateral distribution of geochemical constituents can be used as a secondary line of evidence to evaluate treatment of Sr-90 impacted groundwater.

Geochemical Parameter Distribution Maps (cross section view) - Cross sections will be constructed from influent, intra-well, and effluent PTW wells. Because sorption of Sr-90 to the zeolite structure displaces monovalent cations (potassium, sodium) comparison of geochemical signatures at influent, intra-wall, and effluent cross sections can be used as a secondary line of evidence to evaluate treatment of Sr-90 impacted groundwater.

WVDP-512 Rev. 1 Page 21 of 98 TABLE 3 EVALUATION OF FUNCTIONAL REQUIREMENTS North Plateau Permeable Treatment Wall West Valley Environmental Services, LLC West Valley, New York Functional Requirement Data Analysis

3. Sr-90 contamination should not be redirected Sr-90 Plume Maps (plan view) - Maps depicting the lateral distribution of Sr-90 in the to currently less-contaminated areas. vicinity of the PTW will be developed from groundwater sampling results. Changes in the lateral distribution of Sr-90 will be used as one line of evidence to assess the potential redirection of Sr-90 impacted groundwater to less contaminated areas.

Potentiometric surface maps - Water level measurements will be used to construct potentiometric surface maps. The potentiometric surface maps will be used to assess the movement of Sr-90 impacted groundwater in the vicinity of the PTW.

Hydraulic Testing Data Analysis - Data from slug tests, pressure transducers, and dilution tests will be analyzed to better understand the movement of Sr-90 impacted groundwater in the vicinity of the PTW.

4. Groundwater flow through the PTW should be Potentiometric surface maps - Water level measurements will be used to construct sufficient to preclude substantial changes in potentiometric surface maps. The potentiometric surface maps will be used to assess the groundwater flow patterns that would require movement of groundwater in the vicinity of the PTW.

additional mitigation actions.

Hydraulic Testing Data Analysis - Data from slug tests, pressure transducers, and dilution tests will be analyzed to better understand the movement of groundwater in the vicinity of the PTW.

WVDP-512 Rev. 1 Page 22 of 98 Figure 1 Site Location

WVDP-512 Rev. 1 Page 23 of 98 Figure 2 Site Features

WVDP-512 Rev. 1 Page 24 of 98 Figure 3 Distribution of Sr-90 in Sand and Gravel Unit

WVDP-512 Rev. 1 Page 25 of 98 Figure 4 PTW Alignment

WVDP-512 Rev. 1 Page 26 of 98 Figure 5 February 2010 Soil Boring Locations

WVDP-512 Rev. 1 Page 27 of 98 Figure 6 February 2010 Investigation Results

WVDP-512 Rev. 1 Page 28 of 98 Figure 7 Existing North Plateau Monitoring Network

WVDP-512 Rev. 1 Page 29 of 98 Figure 8 New PTW Performance Monitoring Wells

WVDP-512 Rev. 1 Page 30 of 98 Attachment - A EXAMPLE PTW INSPECTION FORM North Plateau Permeable Treatment Wall Date: Weather:

Inspection By: Time In:

Others On Site: Time Out:

Visual Observations - PTW Platform:

YES NO Comments Corrective Action Required (Y/N)

Improper drainage or excessive ponding?

Subsidence, rutting, or excessive erosion?

Excessive vegetation/overgrowth observed?

New construction/infrastructure observed in vicinity of PTW?

New landscaping observed in vicinity of PTW?

If maintenance is required to resolve any of the above noted items, describe what actions taken, if any. Were all maintenance items resolved during this site visit? If no, what items remain to be resolved?

Visual Observations - Stormwater Infrastructure:

YES NO Comments Corrective Action Required (Y/N)

Debris accumulation in drainage channels?

Damage to drainage channel liner?

Debris accumulation at catch basin inlets?

If maintenance is required to resolve any of the above noted items, describe what actions taken, if any. Were all maintenance items resolved during this site visit? If no, what items remain to be resolved?

WVDP-512 Rev. 1 Page 31 of 98 Note: This form is provided as an example template only and should be modified and updated as needed to reflect current project conditions.

WVDP-512 Rev. 1 Page 32 of 98 Attachment B Well Construction Diagrams for Wells Installed in December 2010

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WVDP-512 Rev. 1 WVDP RECORD OF REVISION Revision On Rev. No. Description of Changes Page(s) Dated 0 Original Issue All 08/26/10 EA, QA are affected by this issue.

1 Revised Plan to reflect actual installation of PTW (Oct - Nov 2010) and 03/15/11 installation of monitoring wells (Dec 2010); specified calendar years associated with monitoring frequencies, etc. based on above installation dates; identified potential DOE-specified alternative data reporting frequency and method; attached new monitoring well logs; revised Figure 8 to reflect as-installed well information; included well specification Tables 1A and 1B.

EA, Environmental Lab and QA are affected by this revision.

WV-1807, Rev. 10 (DCIP-101) i

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