Attachmt_8_FSS.pdf

Attachment 8

Final Site Master FSS Plan

Welsbach / General Gas Mantle Superfund Site

Camden County, New Jersey

Welsbach/General Gas Mantle Superfund Site

Final

Master Final Status Survey Plan Operable Unit 1

March 2016

Report Prepared By:

Arcadis U.S., Inc.

On Behalf of U.S.

Environmental Protection Agency Region 2 06739024 i

Table of Contents

ACRONYMS AND ABBREVIATIONS .................................................................................................... i 1 INTRODUCTION ...................................................................................................................... 1-1

1.1 Site Background ................................................................................................................................. 1-1

1.2 Previous Investigations and Regulatory History ................................................................................ 1-2

1.3 Remedial Objectives ........................................................................................................................... 1-2

1.4 Scope .................................................................................................................................................. 1-3

2 DATA QUALITY OBJECTIVES ............................................................................................. 2-1

2.1 Step 1 – State the Problem.................................................................................................................. 2-1

2.2 Step 2 - Identify the Decision ............................................................................................................. 2-1

2.3 Step 3 - Identify Inputs to the Decision .............................................................................................. 2-2

2.3.1 Historical Information ............................................................................................................. 2-2

2.3.2 Site Cleanup Criteria................................................................................................................ 2-2

2.3.2.1 Soil ...............................................................................................................................2-2

2.3.2.2 Structures .....................................................................................................................2-2

2.3.2.3 Permanent Fixed Structures .........................................................................................2-3

2.3.3 Additional Field Data .............................................................................................................. 2-4

2.4 Step 4 - Define the Study Boundaries ................................................................................................ 2-5

2.4.1 Physical Boundaries ................................................................................................................ 2-5

2.4.2 Data Population ....................................................................................................................... 2-5

2.4.3 Spatial and Temporal Boundaries ............................................................................................ 2-5

2.5 Step 5 - Develop a Decision Rule ....................................................................................................... 2-6

2.5.1 Decision Inputs ........................................................................................................................ 2-6

2.5.2 Parameter of Interest ................................................................................................................ 2-6

2.5.3 Scale of Decision Making ........................................................................................................ 2-6

2.5.4 Action Level ............................................................................................................................ 2-6

2.6 Step 6 - Define Acceptable Limits on Decision Errors ...................................................................... 2-7

2.6.1 Field Measurements and Analytical Data ................................................................................ 2-7

2.6.2 Statistical Tests ........................................................................................................................ 2-7

2.6.2.1 Hypotheses ...................................................................................................................2-7

2.6.2.2 Error Types ..................................................................................................................2-8

2.6.2.3 Relative Shift ................................................................................................................2-8

2.7 Optimize the Design ........................................................................................................................... 2-9 3 FINAL STATUS SURVEY CRITERIA ................................................................................... 3-1

3.1 Release Criteria (Residual Radioactivity Limits) ............................................................................... 3-1

3.2 Reference Area and Data .................................................................................................................... 3-1

3.2.1 Soil ........................................................................................................................................... 3-1

3.2.1.1 Reference Area Data ....................................................................................................3-1

3.2.1.2 Selection of Appropriate Reference Area Data ............................................................3-2

3.2.1.3 Addressing Negative Background Corrected Values ...................................................3-2

3.2.2 Structures ................................................................................................................................. 3-3

3.3 Survey Unit Classification .................................................................................................................. 3-3

3.3.1 General .................................................................................................................................... 3-3

3.3.2 Required Information............................................................................................................... 3-4

3.3.3 Classification Procedures ......................................................................................................... 3-5

3.3.3.1 Class 1 SUs ..................................................................................................................3-5

3.3.3.2 Class 2 SUs ..................................................................................................................3-6

3.3.3.3 Class 3 SUs ..................................................................................................................3-6

3.3.4 Establishing SU Boundaries .................................................................................................... 3-6

3.3.4.1 Class 1 SUs ..................................................................................................................3-6

3.3.4.2 Class 2 SUs ..................................................................................................................3-7

3.3.4.3 Class 3 SUs ..................................................................................................................3-7

3.3.4.4 Inaccessible Areas ........................................................................................................3-7 ii

3.4 Statistical Tests ................................................................................................................................... 3-7

3.4.1 General .................................................................................................................................... 3-7

3.4.1.1 Small SUs .....................................................................................................................3-8

3.4.1.2 Large SUs .....................................................................................................................3-8

3.4.2 WRS Test ................................................................................................................................. 3-9

3.4.2.1 General .........................................................................................................................3-9

3.4.2.2 Applicability .................................................................................................................3-9

3.4.2.3 Performing the Wilcoxon Rank Sum Test.................................................................. 3-10

3.4.3 Elevated Measurement Comparison ...................................................................................... 3-11

3.4.3.1 General ....................................................................................................................... 3-11

3.4.3.2 EMC Steps ................................................................................................................. 3-12

3.4.3.3 EMC Application ....................................................................................................... 3-15

4 MASTER FINAL STATUS SURVEY DESIGN AND METHODOLOGY FOR

CONSTRUCTION SURVEY UNITS .................................................................................................... 4-1

4.1 Identify Survey Units ......................................................................................................................... 4-1

4.2 Establish Survey Reference Coordinate System ................................................................................. 4-1

4.3 Develop Area-specific FSS Design .................................................................................................... 4-1

4.4 Soil scanning Survey Methodology .................................................................................................... 4-2

4.4.1 Trigger Levels .......................................................................................................................... 4-2

4.4.2 Methodology ............................................................................................................................ 4-3

4.5 Structure Scanning Survey Methodology ........................................................................................... 4-3

4.6 Discrete Samples ................................................................................................................................ 4-3

4.7 Laboratory Analysis ........................................................................................................................... 4-4

4.7.1 Scan Minimum Detectable Concentration Considerations ...................................................... 4-4

4.7.2 Location of Measurements/Samples ........................................................................................ 4-4

4.7.3 Location of Bias/Judgment Samples ........................................................................................ 4-5

4.8 Field Records ...................................................................................................................................... 4-6

5 MASTER FINAL STATUS SURVEY DESIGN AND METHODOLOGY FOR

DESIGN SURVEY UNITS ...................................................................................................................... 5-1

5.1 Identify Survey Units ......................................................................................................................... 5-1

5.2 Existing Design Data .......................................................................................................................... 5-1

5.2.1 Scanning Survey ...................................................................................................................... 5-1

5.3 Boring Installation .............................................................................................................................. 5-1

5.4 Required Design Data ........................................................................................................................ 5-2

5.5 Apply Decision Rules Using Statistical Tests .................................................................................... 5-2

5.6 Field Records ...................................................................................................................................... 5-2

6 QUALITY ASSURANCE/QUALITY CONTROL .................................................................. 6-1

6.1 Project Quality Assurance/Quality Control ........................................................................................ 6-1

6.2 Field Instrumentation Requirements .................................................................................................. 6-1

6.2.1 Calibration ............................................................................................................................... 6-1

6.2.2 Source and Background Checks .............................................................................................. 6-1

6.2.3 GPS Requirements ................................................................................................................... 6-2

6.2.3.1 Daily Field Checks .......................................................................................................6-2

6.2.3.2 Quality Control of the Field Survey .............................................................................6-2

6.3 Soil Sampling ..................................................................................................................................... 6-2

6.3.1 Laboratory Approval ............................................................................................................... 6-2

6.3.2 Confirmatory Analysis Samples .............................................................................................. 6-3

6.3.3 Data Validation ........................................................................................................................ 6-3

7 REFERENCES ............................................................................................................................ 7-1 iii

LIST OF TABLES

Table 2-1 Total Surface Limits for Non-metallic Surfaces ........................................................................ 2-3 Table 2-2 Alpha and Beta Surface Limit for Metallic Surfaces ................................................................. 2-4 Table 2-3 Data Required for FSS ............................................................................................................... 2-4 Table 2-4 Cleanup Criteria ......................................................................................................................... 2-6 Table 3-1 Suggested SU Areas .................................................................................................................. 3-4 Table 3-2 Outdoor EMC AFs................................................................................................................... 3-11 Table 3-3 Indoor EMC AFs for EMC Areas Greater Than One Square Meter ....................................... 3-12 Table 3-4 Indoor EMC AFs for EMC Areas Less Than One Square Meter ............................................ 3-12 Table 3-5 Systmatic Samples in 2.8-DSU-1 ............................................................................................ 3-15 Table 4-1 Summary of Integrated FSS Design .......................................................................................... 4-1

LIST OF FIGURES

Figure 1 Site Study Areas

APPENDICES

A Property-Specific Information A1 – Former Welsbach Facility Property A2 – 7th Street Group A3 – Whitman Park North Group B Construction Unit-Specific Historical Information B1 – Former Welsbach Facility Property B2 – 7th Street Group B3 – Whitman Park North Group C Approach for Permanent Fixed Structures D Reference Area Data E Example FSS Tables F FSS Template i

ACRONYMS AND ABBREVIATIONS

AF area factor CAD Computer Aided Design COR Contracting Officer’s Representative CU Construction Units DCGL derived concentration guideline level DCGLEMC derived concentration guideline levels for elevated measurement comparisons DCGLW area wide derived concentration guideline level DHG downhole gamma DI Design Investigation dpm/100 cm2 decays per minute per 100 square centimeter area DQO Data Quality Objective EMC elevated measurement comparison EPA U.S. Environmental Protection Agency FSS Final Status Survey GPD Gas Proportional Detector GGM General Gas Mantle GPS Global Positioning System Ha alternative hypothesis H0 null hypothesis LBGR lower boundary of the gray region m meters m2 meters squared MARSSIM Multi-Agency Radiation Survey and Site Investigation Manual MDC minimum detectable concentration µCi/m2 microcuries per square meter NaI sodium iodide NJ New Jersey NJDEP New Jersey Department of Environmental Protection NORM Naturally Occurring Radioactive Material OU Operable Unit pCi/g picocuries per gram pCi/L picoCuries per liter QA quality assurance QAPP Quality Assurance Project Plan QC Quality Control Ra radium RI/FS Remedial Investigation/Feasibility Study ROC Radionuclide of Concern ROD Record of Decision Site Welsbach/General Gas Mantle Superfund Site SD Standard Deviation SOP Standard Operating Procedure SU Survey Unit Th thorium UFP Uniform Federal Policy USACE United States Army Corps of Engineers WL working level WRS Wilcoxon Rank Sum (statistical test)

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1 INTRODUCTION

This plan establishes the approach for implementing Final Status Surveys (FSSs) at Operable Unit (OU) 1 of the Welsbach/General Gas Mantle Superfund Site (Site), located in the City of Camden and Gloucester City, Camden County, New Jersey (NJ). This Master FSS Plan follows an approach consistent with the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) (EPA 2000a).

1.1 SITE BACKGROUND

Between the 1890s and 1940s, Welsbach manufactured gas mantles at its facility in Gloucester City, NJ.

Beginning around 1895 Welsbach extracted the radioactive element thorium from imported monazite ore.

Welsbach used the thorium in their gas mantle manufacturing process, since thorium caused the mantles to glow more brightly when heated. Just after the turn of the 19th century, Welsbach was the largest producer of gas mantles and lamps in the United States, making up to 250,000 mantles per day. Welsbach went out of business in 1940.

A second gas mantle manufacturing company, General Gas Mantle (GGM), located in Camden, NJ, was a small competitor to Welsbach. GGM operated from 1912 to 1941. While there is little information on its activities, it appears that GGM only used refined thorium in its gas mantle manufacturing processes.

During the years Welsbach was in operation, ore tailings were used as fill at properties in the vicinity of its operations. Over the past 100 years, a number of Welsbach buildings were demolished and the building debris may also have been used as fill in the Gloucester City area.

The Site was initially identified by the U.S. Environmental Protection Agency (EPA) during their investigation at the U.S. Radium Corporation Superfund Site in Orange, NJ. U.S. Radium records indicated they had purchased radium from Welsbach. In 1981, as a result of this information, EPA sponsored an aerial radiological survey of the Camden and Gloucester City areas to investigate for the possible presence of radioactive contamination. Based on an evaluation of these data, EPA identified six study areas. Refer to Figure 1 for a map of the Site.

Study Area 1 – includes the former GGM facility and residential and commercial properties that surround GGM. The former GGM facility is located in a mixed industrial, commercial, and residential section of Camden.

Study Area 2 – includes the former Welsbach Company and nearby residential/commercial properties. The former Welsbach Company is now an active port along the Delaware River in an industrially zoned section of Gloucester City with residential properties immediately to the east.

An original Welsbach era building, the Armstrong building, which is OU2 of the Site, is still present on the property.

Study Area 3 – includes residential and recreational properties in Gloucester City, including the Gloucester City Swim Club, the Johnson Boulevard Land Preserve, and Ball Fields North.

Study Area 4 – includes residential properties in the Fairview section of Camden.

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Study Area 5 – includes residential properties, vacant land, and recreational properties in Gloucester City, including Ball Fields South.

Study Area 6 – includes residential and commercial properties, as well as vacant land, near Market, Powell, and 7th Streets, in Gloucester City.

1.2 PREVIOUS INVESTIGATIONS AND REGULATORY HISTORY

Based on the aerial survey, the New Jersey Department of Environmental Protection (NJDEP) began conducting detailed radiological investigations at more than 1,000 properties in Camden and Gloucester City in the early 1990s. As a result of these investigations, NJDEP identified approximately 100 properties potentially contaminated with radiological materials. At properties where NJDEP determined that exposure levels were unacceptable1, NJDEP performed interim remedial measures including installation of radon/thoron ventilation systems and/or placement of concrete and/or lead sheeting to shield gamma radiation.

EPA placed this Site on the National Priorities List in 1996; four OUs were identified. This FSS Plan addresses the OU1 Record of Decision (ROD) compliance aspects.

OU1 - Soils and Waste Materials – In 1997, EPA contracted Arcadis (formerly Malcolm Pirnie) to perform a Remedial Investigation/Feasibility Study (RI/FS) for OU1. The RI/FS was finalized in January 1999 (Arcadis 1999) and in July 1999 EPA issued the ROD (EPA 1999). The selected remedy is discussed in Section 1.3.

OU2 - Armstrong Building – EPA issued the ROD for this OU in September 2011 (EPA 2011).

The selected remedy included decontamination of radiologically contaminated building surfaces and off-site disposal of radiologically contaminated waste materials. The FSS for this OU is being conducted in accordance with the Field Sampling and Survey Plan, Welsbach/GGM Superfund Site Armstrong Building, April 2013 (USACE 2013).

OU3 - Surface Water, Sediments, and Wetlands – EPA issued the ROD for this OU, which includes a portion of the South Branch of Newton Creek, Martin’s Lake, and a portion of the Delaware River, in July 2005. This ROD indicated that no remedial action was necessary for surface water, sediments, and wetlands at the Site (EPA 2005a).

OU4 – Groundwater – EPA plans to start the RI for OU4 at the completion of the OU1 cleanup activities.

1.3 REMEDIAL OBJECTIVES

The remedial objectives presented in the ROD for OU1 are the following.

Eliminate or minimize the potential for humans to ingest, come into dermal contact with, or inhale, particulates of radioactive constituents, or to be exposed to external gamma radiation in order to achieve the level of protection required by the National Oil Pollution and Hazardous Substances Contingency Plan (i.e., 10-4 to 10-6 risk range).

1 NJDEP took interim action when interior exposure rates were above 27 microRoentgens per hour (µR/h), exterior exposure rates were above 50 µR/h, and/or radon levels were above 4 pCi/L or 0.02 WL.

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Prevent long-term exposure to radium and thorium contaminated material with concentrations greater than 5 picocuries per gram (pCi/g) above background.

Prevent exposure to indoor concentrations of radon gas and radon decay products greater than 4 picoCuries per liter (pCi/L) and 0.02 working level (WL), respectively.

Prevent direct contact with building surfaces exhibiting total surface thorium contamination exceeding 0.026 microcuries per square meter (μCi/m2) [approximately 577 decays per minute per 100 square centimeters (dpm/100cm2)] above background.

Prevent migration of radiologically contaminated material that could result in the exposures described above.

Comply with other chemical, location, and action specific applicable or relevant and appropriate requirements.

To meet these objectives, the selected remedy presented in the ROD for OU1 included the following components:

Excavation and removal of soil and waste materials with radioactive contamination above remedial action objectives [referred to as the Derived Concentration Guidance Level (DCGL)] from the former Welsbach/GGM facilities and the surrounding residential and commercial properties;

Off-site disposal of radiologically contaminated soil and waste materials;

Decontamination and demolition of the GGM facility, as well as other buildings and structures, as required; and

Appropriate environmental monitoring to ensure the effectiveness of the remedy.

1.4 SCOPE

EPA began design and construction work at this Site in 2000. Since then, a large number of properties have been investigated and, as applicable, remediated. This Master FSS Plan is applicable to OU1 at the Site for properties that have not yet been remediated. For the purpose of developing the remedial design, properties requiring remediation are placed into construction units (CU); each CU can consist of one or more properties. Multiple properties are grouped into one CU when radiological contamination is contiguous between the properties. The size (i.e., number of properties and/or acreage), volume of contaminated soil and/or building materials that need to be removed, and/or complexity of remediation (e.g., impact to utilities, excavation support is required) varies significantly between CUs.

The majority of the CUs that still require remediation are relatively small in size and the construction is expected to be uncomplicated. Three CUs currently covered under this plan, the Former Welsbach Facility, the 7th Street Group, and Whitman Park North are complex CUs. Information specific to these three CUs is given in Appendices A1, A2, and A3, respectively. As other complex CUs are identified that require remediation, additional CU-specific information may be added to this appendix.

To determine whether a CU can be released for unrestricted use with respect to Site-related radiological contamination, the CU is subdivided into survey units (SUs). As defined in MARSSIM, a SU is a physical area consisting of structures or land areas of specified size and shape for which a separate

1-4 decision will be made as to whether that area exceeds the release criterion. As a result, the SU is the primary entity for demonstrating compliance with the release criterion.

The objective of this plan is to provide a consistent approach for planning, performing, and assessing site soils and structural surfaces through FSSs in order to demonstrate compliance with established release criteria. Note that this plan addresses the following two types of SUs.

1. SUs where remediation is not required – The FSS at these SUs (design SUs) will be conducted by the design contractor using existing data collected by EPA as part of the design investigations (DIs).

2. SUs where remediation is required – The FSS at these SUs will be conducted by the construction contractor (construction SUs), using data collected by the construction contractor after remedial activities are completed. The remedial activities at these areas will be completed in accordance with the Contractor’s Remedial Action Work Plan.

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2 DATA QUALITY OBJECTIVES

Data Quality Objectives (DQOs) are qualitative and quantitative statements that establish a systematic procedure for defining the criteria by which data collection design is satisfied to make determinations regarding releasing a property or portions of a property for unrestricted use. The DQOs for the Site include the following.

1. Clarifying the project problem;

2. Defining the data necessary for achieving the end use decisions;

3. Determining the appropriate method of data collection; and

4. Specifying the level of decision errors acceptable for establishing the quantity and quality of data needed to support the project decisions.

The overall quality assurance (QA) objective for this project is to develop and implement procedures for obtaining and evaluating data that meet the DQOs to confirm that 1) sufficient data, of acceptable quality, are available to complete the FSS for unremediated areas or 2) confirm that the required remediation is accomplished for areas requiring cleanup. QA procedures are established to ensure field measurements, sampling methods, and analytical data provide information that is comparable and representative of actual field conditions, and that the data generated are technically defensible. To determine the DQOs, a series of planning steps are used to identify the data needed to support project decisions and develop a data collection program (EPA 2000b). The process is intended to be iterative, optimizing data collection to meet the applicable decision criteria. The seven steps, as applied to the Site, are detailed in the following sections.

2.1 STEP 1 – STATE THE PROBLEM

Based on the following, various properties associated with the Site that require or have the potential to require remediation have been identified.

1. During DIs conducted by EPA at numerous properties associated with the Site, elevated levels of the radionuclide of concern (ROC [i.e., radium (Ra)-226, Ra-228, thorium (Th)-230, and Th-232] have been found. EPA has not yet begun remedial activities at some of these properties.

2. EPA has identified numerous properties within the Site Study Areas that have not yet been investigated. Based on data from nearby properties, as well as their proximity to either the Welsbach or GGM facilities, it is possible that these properties contain soil/fill with elevated levels of radioactive material associated with Site operations.

The objective of the FSS is to free-release both remediated and unremediated SUs, as appropriate, with respect to Site-related radiological contamination. The ultimate decision regarding site disposition will rest with the EPA decision makers.

2.2 STEP 2 - IDENTIFY THE DECISION

Survey and sampling data will be used to provide an answer to one of the following questions.

1. “If remediation of a SU was not required, do the existing data and measurements comply with the Site release criteria?”

2. “If remediation of a SU was required, do the post-remediation measurements and data comply with the Site release criteria?”

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2.3 STEP 3 - IDENTIFY INPUTS TO THE DECISION

Several inputs are required to answer the questions identified in Step 2, above. These inputs are detailed below.

2.3.1 Historical Information

Under non-acidic conditions, the ROCs are relatively immobile (Springer 2006). Therefore, Site-related contamination has typically been found in areas associated with fill events, with little transport, if any, outside of the fill areas. The following maps, which outline the fill history, are typically reviewed for each property. Note that not all maps are applicable and/or available for each property. Historical information specific to the Former Welsbach Facility, the 7th Street Group, and the Whitman Park North Group are contained in Appendices B1, B2, and B3, respectively.

Sanborn Maps2 (available from http://library.princeton.edu/libraries/firestone/rbsc/aids/sanborn/camden/)

US Geological Survey Topographic Maps (available from http://historicalmaps.arcgis.com/usgs/)

Aerial photographs (available from http://www.historicaerials.com/ as well as EPA aerial photographic analysis reports)

US Coast and Geodetic Survey Navigational Charts (available from http://historicalcharts.noaa.gov/)

2.3.2 Site Cleanup Criteria

OU1 primarily consists of soils (i.e., land areas) containing elevated levels of radioactivity3. During remediation of these soils, structures and permanent fixed structures may also be encountered. Definitions of each, the associated cleanup criteria, as well as guidelines for when structures and permanent fixed structures are included in the OU1 remediation, are given in Sections 2.3.2.1, 2.3.2.2, and 2.3.2.3, respectively.

2.3.2.1 Soil

These are land areas containing in-situ soil; the soil may or may not be present underneath a structure.

The selected remedy presented in the ROD includes excavation and off-site disposal of radiologically contaminated soils with activities greater than 5 pCi/g total radium or 5 pCi/g total thorium above background. The appropriate background concentrations are given in Section 3.2.

2.3.2.2 Structures

These include the materials used to construct aboveground structures (or portions of these structures) intended for human use or habitation (e.g., brick basement floor, concrete basement wall). Structures will typically be included in OU1 remedial activities when the structures are collocated with soil (e.g., a house located above contaminated soil). An example is given below.

2 Originally created in 1867 to assess fire insurance liability in urbanized areas in the United States, Sanborn maps contain detailed building information.

3 Throughout this document elevated levels of radioactivity is used to indicate levels above the DCGL.

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The selected remedy presented in the ROD includes removal and off-site disposal of habitable building materials exhibiting total surface thorium contamination exceeding 0.026 μCi/m2 above background. The FSS for structures, as well as any required post-remediation surveys, will be conducted in accordance with the FSS approach detailed in MARSSIM. The Field Sampling and Survey Plan, Welsbach/GGM Superfund Site Armstrong Building, April 2013 (USACE 2013) may also be used for guidance.

Example: When Structures are Included in OU1 Remedial Activities

During a DI at a residential property, exposure rate scans are typically conducted in the basement to determine if contaminated soil is present underneath the basement floor. If it is determined during the scan that the brick used to construct the floor contains elevated radioactivity, the brick floor would be remediated under OU1. Note that whenever structures will be remediated under OU1 this information will be noted by the design contractor in the remedial design for the CU.

2.3.2.3 Permanent Fixed Structures

These include the materials used to construct structures, located in-situ in land areas, which were either not designed for human occupancy (e.g., pipes, subsurface foundations) or are no longer being used for human use or occupancy (e.g., a building that was demolished and left in place). The FSS approach for permanent fixed structures is given in the Approach to Structure Final Status Survey at Welsbach/GGM (USACE 2016b), which is contained in Appendix C. As discussed in Appendix C, there are two cleanup criteria for permanent fixed structures encountered at the Site depending on whether or not volumetric samples can be collected.

1. If volumetric samples can be collected, the cleanup criteria is less than 5 pCi/g total radium isotopes or 5 pCi/g total thorium isotopes above background concentrations. The background concentrations are given in Section 3.2.2.

2. If volumetric samples cannot be collected the following cleanup criteria will be used.

a. Non-Metallic Materials – Refer to Table 2-1

b. Metallic Materials – Refer to Table 2-2.

Table 2-1 Total Surface Limits for Non-metallic Surfaces

Material Surface limit – beta

(dpm/100 cm2) Surface limit - alpha

(dpm/100 cm2) Surface limit – total

(dpm/100 cm2)

Concrete 7,404 12,765 20,169 Wood 1,610 2775 4385 Brick 7,404 12,765 20,169

Asphalt 4,829 8325 13,154 Granite 8,691 14,985 23,676

Sand Stone 6,116 10,545 16,661

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Table 2-2 Alpha and Beta Surface Limit for Metallic Surfaces

Basis Radiation Type Total (dpm/100 cm2)

ANSI 13.12

Alpha 360

Beta 180

2.3.3 Additional Field Data

One of the objectives of the survey and sampling activities is to quantify the concentrations of residual radioactive material in the SUs. This information will allow a determination of whether a SU is suitable for release. The average soil concentrations and structural surface activities will be evaluated to determine if the radiological DCGLs are met. To perform this assessment the field data listed in Table 2-3 may be required.

Table 2-3 Data Required for FSS

Data Needed SU Type Comments Collection

Procedure Basis

Surface exposure rate scans and/or gamma count measurements

Design

Based on existing DI data; supplemental data may be required if a SU does not have sufficient coverage (e.g., DI covered 50% of an area classified as a Class 1 SU).

Design uniform federal policy-quality assurance project plan (UFP-QAPP)1

Construction Conducted after remediation complete on 100 percent of the excavated area including excavation floors and sidewalls.

Master FSS Plan Sections 4.4 and 4.5

Downhole gamma

(DHG)

measurements Design

Based on existing DI data. As appropriate supplemental step-out borings may be installed to:

1. Determine the area for a boring being evaluated with the elevated measurement comparison (EMC).

2. Provide additional coverage in areas that do not have sufficient coverage to fully evaluate the SU.

Design UFP-QAPP

Radiological soil samples

Design

Based on existing DI data. As appropriate supplemental samples may be collected to:

1. Determine the area for a sample being evaluated with the EMC.

2. Provide additional coverage in areas that do not have a sufficient number of samples to fully evaluate the SU.

Design UFP-QAPP

Construction Collected after remediation complete; both systematic and bias samples required.

Construction UFP- QAPP; Master FSS

Plan Sections 4.6 and 4.7

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Data Needed SU Type Comments Collection

Procedure Basis

Radiological volumetric material samples (e.g., concrete, brick, wood)

Design

Based on existing DI data. As appropriate supplemental data may be collected prior to completing the FSS if a sufficient number of samples are not available for the SU.

Design UFP-QAPP;

Permanent Fixed

Structure FSS Approach (USACE

2016)

Construction Collected from permanent fixed structures located within excavations.

Permanent Fixed Structure FSS

Approach (USACE 2016)

Alpha/beta measurements

Construction Collected from permanent fixed structures within excavations when volumetric samples cannot be collected.

Permanent Fixed Structure FSS

Approach (USACE 2016)

Note:

1. To ensure the quality of the data collected, both the design and construction contractor are required to develop a

UFP-QAPP that is followed for field measurement and sample collection, as well as field measurement and sample collection quality assurance/quality control (QA/QC). Throughout this document, whenever a UFP- QAPP is referenced, reference is made to the design contractors’ UFP-QAPP for all data collected during the design investigations and the construction contractors’ UFP-QAPP for all data collected as part of construction activities.

These data will be used in the FSS to

1. Demonstrate that the existing radionuclide concentrations or the residual radionuclide concentrations following remediation in a SU comply with concentration and exposure-based criteria per the ROD (EPA 1999);

2. Demonstrate that the survey data meet the requirements of the MARSSIM methodology; and

3. Document the results of the investigations, remediation (if applicable) and FSS.

2.4 STEP 4 - DEFINE THE STUDY BOUNDARIES

2.4.1 Physical Boundaries

The physical boundaries of the Site are shown on Figure 1. The physical boundaries of each SU will be determined by the design and construction contractors, as appropriate and in accordance with Section 3.3.4.3.

2.4.2 Data Population

The data population of interest for the properties is the concentration of ROCs and their associated comparison to the release criteria in soils and/or structural surfaces. A separate data population of interest is the activity concentration of ROCs in the designated background reference areas.

2.4.3 Spatial and Temporal Boundaries

The spatial boundaries of the project are horizontally limited to structures and land areas located within the property boundaries. The vertical study area includes all land masses extending from the land surface to a depth of up to approximately 35 feet below ground surface and all potentially impacted structures, which have been previously characterized as being potentially contaminated. The study period begins

2-6 with acceptance of this document by the EPA decision makers and runs throughout the duration of the Site remedial action.

2.5 STEP 5 - DEVELOP A DECISION RULE

2.5.1 Decision Inputs

Scanning, fixed point measurements, surface activity measurements, and/or sampling and analysis will be used to evaluate SUs. Results will be compared to cleanup criteria discussed in Section 3.1 and summarized in Table 2-4. Determination of whether ROC concentrations at a property exceed background concentrations by more than the release criteria will be made using all collected data and a strict statistical methodology (discussed in detail in Section 3.4). If the SU does not meet the DCGLs further investigation and/or remediation is warranted. This application of decision rules or investigation levels may prompt additional samples, further remediation, or reclassification of the SU. If the SU meets the DCGLs no further action will be required.

Table 2-4 Cleanup Criteria

Radionuclide Soil Structural Surfaces2

Total Radium < 5 pCi/g above background1

< 5 pCi/g above background

< 577 dpm/100 cm2 above background Total Thorium

Notes:

1. Background concentrations for soil and structural surfaces are given in Section 3.2.

2. The cleanup criteria for structural surfaces is dependent on whether or not volumetric samples could be collected and whether the structure is habitable.

2.5.2 Parameter of Interest

Parameters of interest are the mean, median, and standard deviation (SD) of data collected during the study. Nonparametric statistical tests (as discussed in Section 3.4) will be utilized to determine whether the level of residual activity uniformly distributed throughout the SU exceeds the cleanup criteria. Since these methods are based on ranks, the results are generally expressed in terms of the median. In some cases, the mean may exceed the median. For this reason, the arithmetic mean of the SU data will also be compared to the cleanup criteria as a first step in the interpretation of data. By using a graded approach to data testing as discussed below, decisions will be made according to the decision rule stated at the end of this discussion.

2.5.3 Scale of Decision Making

Decisions are made on two fundamental scales; the SU and smaller localized areas of elevated activity.

Localized areas of elevated radiation levels are evaluated on a continuous basis. During the field effort, every attempt will be made to remediate any localized areas that exceed the cleanup criteria. On a larger scale, and as a final determination, data will be evaluated on a SU-specific basis. SU boundaries will be established according to the methodology discussed in Section 3.3. During the FSS, for localized areas with radioactive concentrations above the DCGL an EMC will be performed (Section 3.4).

2.5.4 Action Level

Decisions on a SU’s acceptability are based on a comparison of the measured residual radioactivity concentrations in SUs and the background, subject to applicable statistical analyses specified in

MARSSIM.

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2.6 STEP 6 - DEFINE ACCEPTABLE LIMITS ON DECISION ERRORS

This step is used to specify the decision-maker’s acceptable limits on decision errors, which are used to establish appropriate performance goals for limiting uncertainty in environmental data. Acceptable decision errors must be developed for field measurements, analytical data, and statistical tests. Each is described below.

2.6.1 Field Measurements and Analytical Data

Both field measurements and laboratory data will be used in the decision making process. The acceptable limits on decision errors for both of these are defined in the approved UFP-QAPP developed by both the design and construction contractors4. For the design data, the UFP-QAPP has already been developed (Arcadis 2010). The construction contractor will need to develop a UFP-QAPP, which will be approved by the United States Army Corps of Engineers (USACE) and EPA, for each property or group of properties where remediation is conducted.

2.6.2 Statistical Tests

The main statistical test used to determine if the SU meets the release criteria is the Wilcoxon Rank Sum (WRS) test, which is a nonparametric statistical test that compares the medians of two independent data sets (SU samples and background samples) to determine if there is a significant difference between them.

The median of the systematic sample results is compared to the median of the adjusted reference results, which is obtained by adding the DCGL to the sum of the radium and thorium background concentrations.

If the medians are far enough apart, the test will identify them as statistically different, at a chosen level of confidence.

If any measurement results are found to exceed the DCGL but the SU passes the WRS test, then an EMC test must also be performed. The derived concentration guideline levels for elevated measurement comparisons (DCGLEMC) is defined as the highest concentration within a smaller area within the SU that would allow the dose based release criteria to be met for the smaller area. The concentration found in the elevated area is deemed acceptable if the DCGLEMC is not exceeded. The DCGLEMC is calculated by multiplying the DCGL by an area factor (AF), where the AF is the magnitude that the concentration in a specific area can exceed the DCGL while the dose-based release criteria is still met. The EMC test is performed if any of the samples exceed the DCGL plus background.

2.6.2.1 Hypotheses

The decisions necessary to determine compliance with the soil cleanup criteria are based on precise statistical statements called hypotheses, which are tested using the radium and thorium measurement results from the SU and the background reference area.

1. Null Hypotheses - The situation that is presumed to exist is expressed as the null hypothesis (H0), which states “the median concentration in the SU exceeds the median concentration in the background reference area by more than the DCGL.”

2. Alternative Hypotheses - For a given H0, there is a specified alternative hypothesis (Ha), which is an expression of what is believed to be the situation if the H0 is not true. The Ha states “the

4 The UFP-QAPP is updated at least every five years or whenever there is a significant change on the project. The design investigations completed by Arcadis were completed under the original QAPP, developed in 2000, as well as QAPPs that were updated in 2005, 2010, and 2012.

2-8 median concentration in the SU does not exceed the median concentration in the background reference area by more than the DCGL.”

These hypotheses were chosen for the following two reasons.

1. The burden of proof is placed on the H0 and the SU will not be released until proven to meet the cleanup criterion. In order to pass the WRS using the above H0, the median concentration of the systematic samples in the SU must be less than the cleanup criteria.

2. Concentrations of radium and thorium that are below the DCGL are measurable.

2.6.2.2 Error Types

Statistical acceptability decisions are always subject to error and releasing a SU that requires additional remediation is an unacceptable alternative. Two possible error types are associated with such decisions, Type I and Type II, which are described below.

1. Type I – which is also referred to as a false positive, occurs when H0 is rejected when it is actually true. The probability of a Type I error is usually denoted by . This error could result in higher potential doses to future site occupants than prescribed by the dose-based criterion. For the Site the maximum Type I error rate has been set at 0.05 (95 percent confidence level).

2. Type II – which is also referred to as a false negative, occurs when H0 is not rejected when it is actually false. The probability of a Type II error is usually denoted by . The power of a statistical test is defined as the probability of rejecting the H0 when it is false. It is numerically equal to 1-. Consequences of Type II errors include unnecessary remediation expense and project delays. For the Site the Type II error rate has been set at 0.10.

2.6.2.3 Relative Shift

The relative shift is the width of the grey region, or shift, Δ, in terms of the number of SDs of the measurement data, σ, and is designated as the DCGL minus the lower boundary of the gray region (LBGR) divided by σ. The relative shift is an expression of the resolution of the measurements in terms of measurement uncertainty. The value of the relative shift is used to calculate the number of samples required to demonstrate that a SU has met the applicable release criteria. Therefore, the smaller the relative shift, the larger the number of samples. The degree of difficulty in distinguishing the LBGR from the DCGL depends on the variability of the data as well as the size of the shift.

The LBGR is a concentration that is less than the DCGL; it is chosen to be easily distinguishable from the DCGL. A statistical test is applied to the data to determine whether the true concentration in the SU is above the DCGL or below the LBGR. Inaccurate decisions are more likely if the true concentration of the SU is between the LBGR and the DCGL. Thus, it is called the grey region.

The LBGR and the target value for Δ are selected during the DQO process. For the Site these values are set at the following.

LBGR – one-half the DCGL

Shift (Δ) – DCGL minus the LBGR

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2.7 OPTIMIZE THE DESIGN

1. Design SU Data - This FSS design follows the framework for design outlined in Sections 4 and 5 of MARSSIM (EPA 2000a) and includes surface scanning, gamma logging and subsurface sampling.