Final status survey rpt for Dudley Blvd radiological ...

FINAL

FINAL STATUS SURVEY REPORT

DUDLEY BLVD RADIOLOGICAL REMOVAL ACTION

FORMER MCCLELLAN AIR FORCE BASE SACRAMENTO, CALIFORNIA

Prepared under contract to:

Air Force Center for Engineering and the Environment (AFCEE) At the former McClellan Air Force Base

Prepared for:

CH2MHILL. CH2M Hill Constructors, Inc.

155 Grand Avenue, Suite #800 Oakland, California 94612

Prepared by:

Environmental Dimensions, inc. 710 S. Illinois Ave., Ste. F-105

Oak Ridge, TN 37830

August 2012

SFUND RECORDS CTR

2293149

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DEPARTMENT OF THE AIR FORCE AIR FORCE REAL PROPERTY AGENCY

MEMORANDUM FOR SEE DISTRIBUTION

FROM: AFRPA Western Region Execution Center 3411 Olson Street McClellan CA 95652-1003

AUG·3 1 2012

SUBJECT: Submission of Final Status Survey Report, Dudley Blvd. Radiological Removal Action. Final (DSR# 2111-3), Former McClellan Air Force Base, California

1. Enclosed is the Final version of the Final Status Survey Report. Dudley Blvd. Radiological Removal Action (DSR# 2111-3 ). Comments on the Draft Final version of the report have been addressed, and a table showing responses to comments is included in the document.

2. Any questions related to this document should be directed to Mr. Steve Mayer, AFRI,A Radiation Safety Officer at (916) 643-0830 ext. 224. or Mr. Buddy Walser AFRPA Radiation Project Manager at (916) 643-0830 ext. 236.

ftA~ STEVEN K. MAYER, P.E. BRAC Environmental Coordinator

Attachment: Final Status Survey Report. Dudley Blvd Radiological Removal Action, Final (CH2M HILL 2012)

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DISTRIBUTION LIST

Address

AFRPA Western Region Execution Center Attn: Mr. Steve Mayer

Mr. Buddy Walser (Noblis) Administrative Record

3411 Olson Street McClellan CA 95652-1 003

U.S. Environmenta1.Protection Agency, Region IX Attn: Mr. Charnjit Bhullar (SFD-8-1) 75 Hawthorne Street San Francisco CA 941 05

Dept. of Toxic Substances Control Attn: Mr. Stephen Pay 8800 Cal Center Drive Sacramento CA 95826-3200

Central Valley Regional Water Quality Board Attn: Mr. James Taylor II 020 Sun Center Drive #200 Rancho Cordova CA 95670-6114

California Department of Public Health EnvironmeJ:ttal Management Branch Attn: Mr. Kurt Jackson 1616 Capitol Avenue (MS 7405) Sacramento CA 95814

TechLaw Inc. Attn: Mr. Rich Howard 921 II th Street, Suite 800 Sacramento CA 95814

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FINAL

FINAL STATUS SURVEY REPORT

DUDLEY BLVD RADIOLOGICAL REMOVAL AC'fiON

FORMER MCCLELLAN AIR FORCE BASE

SACRAMENTO, CALIFORNIA

Prepared under contract to:

Air Force Center for Engineering and the Environment (AFCEE) At the former McClellan Air Force Base

Prepared for:

CH2MHILL. CH2M Hill Constructors, Inc.

155 Grand Avenue, Suite #800 Oakland, California 94612

Prepared by:

Environmental Dimensions, inc. 710 S.lllinois Ave., Ste. F-105

Oak Ridge, TN 37830

August2012

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REVllSHON RJECODID

Final Status Survey Report Dudley Blvd Radiological Removal Action

Former McClellan Air Force Base

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• 1.0

1.1

1.2

1.3

2.0

2.1

2.2

2.3

3.0

3.1

3.1.1 3.1.2 3.1.3 3.1.4 3.1.5

• 3.1.6 3.1.7 3.1.8

4.0

4.1

4.2

4.2.1 4.2.2 4.2.3 4.2.4

4.3

4.4

4.4.1 4.4.2

4.5

4.6

4.6.1 4.6.2

5.0

5.1

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TABLE OF CONTENTS



INTRODUCTION AND BACKGROUND ............................................................................................. 3

SITE DESCRIP'I'ION ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 3

SITE HISTORY ........................................................................ " ................................................................ 4

RADIONUCLIDE OF CONCERN ................................................................................................................. 4

RELEASE CRITERIA ............................................................................................................................. 5

SOILS CLEANUP CRITERIA ...................................................................................................................... s suRFAcE coNTAMINATioN CRJTERIA ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• s ACTION LEVEI5/CRITERIA APPLICATION ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 6

DATA QUALITY OBJECTIVES AND SURVEY DESIGN .................................................................... 6

PROJECT DATA QUALJ1Y 0BJECTIVES., •• .,.,,.,_.,., ••••• , • ., •• ,., • .,,., • ., • ., •• , •• , •••••• ,.,., ••••• ,., •••• , •• ., •• , • .,.m••"••••••••6

Step l -State the Problem •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 7 Step 2 -Identify the Decision •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 7 Step 3 -Identify Inputs to the Decision ..................................................................................... 7 Step 4 -Define the Study Boundaries ....................................................................................... 8 Step 5- Develop a Decision Rule •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 8 Step 6- Define Decision Errors ................................................................................................. 8 Step 7 - Optimize Survey Design •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 8 Deviations from the Survey Design ......................................................................................... 12

FINAL STATUS SURVEY .................................................................................................................... 12

SuMMARY OF REMEDIATioN AcrMTIES •.•••••.••.•••.••••••••••••.•••.••••••.•••••••••••••••••••.•••••••••••••••••••.•••••••••••• t2

GENERAL FIELD OPERATIONS ............................................................................................................ 13

Quality Contro1 •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 14 Co/ibrotion ond Mointenonce ................................................................................................. 14 Daily QC Source Checlcs ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 14 Detection Sensitivity ............................................................................................................... 14 DETERMINATION OF SCAN MDC (NAI 2x2) ....................................................................................... 19

TOTAL UNCERTAINTY ERROR (TUE) ................................................................................................ 19

Surface and Walkover Surt~eys •••••••••••••••••••••••.••••••••••••••••••••••••••••.•••••••••.••••••••••••••••.•••••••••••••••• 19 Onsite Laboratory ................................................................................................................... 20 SURVEY AND SAMPLING METHODS .................................................................................................... 21

SURVEY REsuL1'S ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••.......••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 22

Excovoted Lond Areo .............................................................................................................. 22 Surface Release ....................................................................................................................... 29

DATA EVALUATION ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 30

DATA QUALITY AsSESSMENT ............................................................................................................. 30

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5.2

5.3

6.0

7.0

Final Status Survey Report

Dudley Blvd Radiological Rem~>Val Action


DOSE ASSESSMENT ............................................................................................................................. 40

ON SITE WORKER DOSE ...................................................................................................................... 40

CONCLUSION ....................................................................................................................................... 41

REFERENCES ....................................................................................................................................... 41

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APPENDICES

APPENDIX A-FIGURES

APPENDIX 8-FIELD INSTRUMENT QC DOCUMENTATION

APPENDIX (-INSTRUMENT CALIBRATION CERTIFICATES

APPENDIX D-SURFACE RELEASE DATA

APPENDIX E-FIELD SAMPLE LOGS

APPENDIX F-LABORATORY DATA

APPENDIX G-AIR MONITORING DATA

APPENDIX. H-ONSITE LABORATORY DAILY SOURCE CHECKS

APPENDIX I-PHOTO LOG

APPENDIX J-DOSE ASSESSMENT

APPENDIX K-ONSITE LABORATORY FINAL STATUS DATA SUMMARY

APPENDIX L-MAJORALAN HALE (USAFSAM/OEHH) SITE VISIT REPORT

APPENDIX M~TUE ANALYSIS BY GUM

APPENDIX N-RESPONSE TO COMMENTS



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LIST OF TABLES

TABLE 1. REMOVAL ACTION AND SU BOUNDARY POINT LOCATIONS

TABLE 2. DUDLEY SURVEY UNIT SYSTEMATIC SAMPLE LOCATION COORDINATES

TABLE 3. RADIATION DETECTION INSTRUMENTATION INVENTORY

TABLE 4. SUMMARY OF FSS INSTRUMENT PERFORMANCE SPECIFICATIONS

TABLE 5. STATIC COUNT MEASUREMENTS, ON CONTACT, 1 MINUTE COUNTS

TABLE 6. SYSTEMATIC SOIL SAMPLE REsuLTS FOR FINAL STATUS SURVEY

TABLE 7. NON-SYSTEMATIC SOIL SAMPLE RESULTS FOR FINAL STATUS SURVEY

TABLE 8. POST ADDITIONAL REMOVAL ACTION SAMPLES

TABLE 9. FINAL SITE CONDITIONS, ALL SAMPLES

TABLE 10. DAILYSRM (5.12 PCI/G) SOURCE CHECK PERFORMANCE

TABLE 11. 0NSITE/0FFSITE LABORATORY EvALUATION

LIST OF FIGURES

FIGURE 1 REMOVAL ACTION AND SURVEY UNIT BOUNDARIES

FJGURE2

FIGURE3

FIGURE4

FIGURE 5

FIGURE6

FIGURE7

FIGURES

FIGURE9

REFERENCE AREA GAMMA WALKOVER SURVEY

FINAL STATUS GAMMA WALKOVER SURVEY

POST ADDITIONAL REMOVAL ACTION WALKOVER SURVEY

FINAL STATUS SYSTEMATIC SAMPLE LOCATIONS

FINAL STATUS PROFESSIONAL AND BIASED SAMPLE LOCATIONS

POST ADDITIONAL REMOVAL ACTION SAMPLE LOCATIONS

FINAL CONDITION SAMPLE LOCATIONS

FINAL CONDITION POSTING PLOT

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ACRONYMS I



AFJ ................ : ........................................................................................... ' ................. Air Force Instruction . . I

AFRPA ...................................................................................................................... Air Force Real Property Agency ASME ................................................................................. : ....................................... American Society of Mechanical·

· I Engineers CFR ............................................................................................................................ Code of Federal Regulations cmz ............................................................................................................ l ................ ·square centimeter Cpm .......................................................................................................... : ................ counts per minute coc ........................................................................................................... l ................ chain-of-custody d ................................................................................................................. ! ................ days DCGL ........................................................................................................ : ................ Derived Concentration Guideline Limit DOE ........................................................................................................................... US Department of Energy DOECAP ................................................... : .............................................. ! ................ Department of Energy Consolidated Audit

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Program . dpm .............. : ........................................................................................... : ................ disintegrations per minute DQO ........ : ................................................................................................. J ................ Data Quality Obj~ctive EMC ........................................................................................................................... Elevated Measurement Comparison EPA ........................................................................................................... J ................ U.S. Environmental Protection Agency FSP ............................................................................................................ : ................ Field Sampling Plan · FSS ............................................................................................................................. Final Status Survey FSSP ............................................... : ........................................................... 1 •••••••••••••••• Final Status Survey Plan GPS ........................................................................................................... ! ................ Global Positioning System HPGe ......................................................................................................... 1

•••••••••••••••• High Purity Germanium JEC ........................................................................................................... ..1. ......... : ..... International Electrotechnical ISO ................ : ............................................................................................ 1

•••••••••••••••• International Organization for ' , Standardiiatiol)

keV ........................................................................................................... ..I_ ••.•••••••.•••. thousand electron volts LBG R ............ : ............................................................................................ ; ............ -. .. Lower Bound of the· Gray Region m ............................................................................................................... .' ................ minutes

~~::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::1:::::::::::::: ~~:~:e~~~:: I

MARLAP ................................................................................................... , ............... Multi-Agency Radiological Laboratory : Analytical Protocols

MARSSIM ................................................................................................. l ............... Multi-Agency Radiation Survey and Site Investigation Manual

McClellan ................................................................................................................. former McClellan Air Force Base MDA ............. : ............................................................................................ ; ............... Minimum Detectable·Activity I . . MDCR ........... : ............................................................................................ : ............... minimum detectable count rate MeV ........................................................................................................... : ............... million electron volts mRem ....................................................................................................... ! ............... millirem Nal ............................................................................................................................. sodium iodide NELAC ...................................................................................................... !. .............. ~ational Environmental Laboratory

I Accreditation Conference NELAP ...................................................................................................... : ............... National Environmental Laboratory

I Accreditatio~ Program NQA-1 ....................................................................................................................... Nuclear Quality Assurance, Levell NRC. ............................................................................................................ , ............... U.S. Nuclear Regulatory Commission OU ............................................................................................................... ' ............... Operable Unit

C./ , I • C . p 1 g ............ , ............................................................................................................. p1co unes per gram QA .............................................................................................................................. Quality Assurance QAPP .......................................................................................................... 1 ••••••••••••••• Quality Assurance Project Plan

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QC ............................................................................................................................... quality control Ra ............................................................................................................................... Radium (e.g., 226Ra) RAM ........................................................................................................................... radioactive material RAO ........................................................................................................................... Removal Action Objectives RIC ............................................................................................................................. Radioisotope Committee SU ............................................................................................................................... Survey Unit TUE ............................................................................................................................ Total Uncertainty Error UCL ............................................................................................................................ Uppe_r Confidence Limit WRS .............. : ............................................................................................................ Wilcoxon Rank Sum Y .................................................................................................................................. years

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EXECUTIVE SUMMARY



This Final Status Survey Report (FSSR) describes the results of the Final Status Survey (FSS) of the former McClellan Air Force Base (McClellan) Dudley Blvd site. Radiological data was collected and analyzed in accordance with the Final Status Survey Plan Field Sampling Plan, Dudley Radiological Removal Action (September 2011) (FSSP) to demonstrate compliance with the criteria for unrestricted radiological release of the excavated area following the requirements of Air Force Instruction AFI 40-201, Managing Radiological Material in the Air Force and following guidance from Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM). The FSSP governing this work is Appendix A to the Dudley Blvd Non-Time Critical Removal Action Work Plan (September 2011) (RAWP).

The Dudley Blvd site is located in Operable Unit A. This site is approximately 10,760 square feet and is southwest of Dudley Blvd and Dudley Loop. Previous investigations indicated the presence of radiological contamination. Although the source of the radiological contamination is not known, it is suspected that the area stored radium dials, radium waste, or radium paint The Dudley Blvd site is at the entrance of a motor pool and at the end of a railroad spur, suggesting a vehicle transporting liquid or a railcar loadingjunloading liquid may have caused the release. Based on extensive sampling that was done in support of the 2011 removal action (described in this FSSR), it appears that a spill occurred, and that the spilled material penetrated into the soil and migrated laterally through coarse-grained sands and gravels associated with the former railroad spur (i.e., railroad ballast). The Dudley Blvd site is included in the US Air Force Radioisotope Committee, Permit #CA-00366-00/02 to authorize the remediation of the radium-226 (226Ra) contamination.

Although the site conceptual model remained unchanged the affected area was larger than originally anticipated. The excavation, originally planned as four smaller excavations extending over an area of approximately 2,000 square feet (186 square meters) and to a depth of 1.5 feet bgs, became one large excavation area that covered an area of roughly 4,400 square feet ( 400 square meters) and ranged in depth from 1 to 3 feet bgs. The final total volume removed was 120 cubic yard (CY) (90 CY soil, 30 CY asphalt) versus a planned total removal volume of74 CY (24 CY soil, 50 CY asphalt). The increased excavation was a result of226Ra contamination being somewhat deeper and to a larger aerial extent than originally anticipated. Excavation work that was planned for two days ended up taking 46 days to identify and remove all of the contaminated media.

Reasonable efforts were made to remediate the Dudley Blvd site. A series of multiple excavations (bqth machine and manual), step out sampling. surface scans, and surveys were performed as the contamination was chased and removed. Excavation began in September 2011 with a projected duration of two days to remove the contamination originally anticipated to be within four distinct areas. Initially, excavation at each of the four areas was completed to the planned areal extents and depths following the requirements of the RAWP. The contamination in asphalt was successfully removed as evidenced by survey results. However, field screening and analytical results identified the need to continue excavation of soil to greater depths and over a larger area. The contamination in soil was determined to be associated with a sand trench containing coarse-grained sands and gravels associated with the former railroad spur (i.e., railroad ballast), rather than isolated spots of contamination in soil underlying asphalt Once the four areas were excavated, additional 226Ra contamination was found to be present extending into the sand trench. Excavation continued in a series of lifts until the field screening and analytical results indicated that cleanup levels had been attained and the site was ready for final status survey. Additionally, elevated readings were discovered to be associated with pieces of old asphalt that had been used to backfill around the base of a telephone pole and at the base of a concrete sto,rm water drainage junction box. Additional excavation was performed to remove remaining pieces of asphalt and additional measurements and samples were collected.

Major Alan Hale with the United States Air Force School of Aerospace Medicine/Radiation Health Branch (USFAM/OEHH) visited the site during the week of September 26, 2011. The purpose of his visit was to provide oversight and independent evaluation of the field removal action and final status survey activities. In Major Hale's report he concludes that; "While the task was completed as requested, unfortunately the

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independent measurements were unable to be taken after complete remediation. Therefore, the measurements represented in this (subject Site Visit Report) should not be used for potential unrestricted release of the site by the Radioisotope Committee Secretariat; rather, the post remediation measurements taken by the contractor should be used as the criteria for potential unrestricted rel~ase of the site. However, observations of the remediation and survey work indicate the contractor was fully competent addressing the radiological conditions at the Dudley Boulevard site."

A comparison and evaluation of the onsite versus the offsite .analytical data indicate a satisfactory correlation with a· coefficient of correlation equal to 0.9769. Additionally, the summary statistics were acceptable, including the median, mean, and standard deviation.

No radioactive waste was generated as a result of this FSSR. A general area air monitoring station was established downwind of the excavation activities to collect fugitive dusts during excavation and load out activities and the occupational Derived Air Concentration for 226Ra of 3x10-10 microcuries per milliliter was not exceeded.

Once the 226Ra contamination was removed, the site was ready for final status survey. There was a single Class 1 survey unit and no Class 2 or Class 3 survey units. The final status survey included a 100 percent gamma walkover survey, direct measurements and surface soil samples from 13 systematic locations (as specified in the FSSP). Additionally, locations were selec~ed based upon; professional judgment (2), biased indicated by gamma walkover survey (3), and following minor additional removal action (5). Screening and investigation levels for gamma walkover survey data were established. Warning levels were set at values between two and three standard deviations above the mean, with investigation required for areas greater than three standard deviations. All soil samples were analyzed by the on-site laboratory for 226 Ra. In order to provide confirmation and verification of the analytical data set, a subset of samples were sent to a qualified off-site analytical laboratory to compare to on-site results. Correlations between onsite and offsite laboratory analyses indicated acceptable agreement and correlation.

All gamma walkover results were less than three standard deviations above the mean. The gamma walkover data statistics compared well with reference area walkover data to confirm the absence of elevated site 226Ra concentrations.

The mean concentration of 226Ra remaining at the site was 0.85 picocuries per gram (pCif g). The mean concentration is less than the remedial action objective of2.0 pCifg. No individuai 226Ra concentration exceeded the design a priori Elevated Measurement Comparison criteria of3.84 pCijg. The survey unit passes the Wilcoxon Rank Sum Test for a DCGL of 1.2 pCifg. Surfaces of items remaining at the site (e.g. the manhole cover, telephone pole, and utility box) met surface release criteria in accordance with U.S. Nuclear Regulatory Commission Regulatory Guide 1.86.

Using RESRAD Version 6.5 and restrictive exposure scenario settings the future dose in excess of background was determined to be less than 2 millirem per year.

The excavation has reduced residual radioactivity sufficiently to allow release of the site for unrestricted use. Net mean radioactivity is less than the DCGL. Gross mean radioactivity is less than 2.0 pCijg. Dose is less than two millirem per year. This was accomplished by conducting the excavation in multiple steps using field measurements and on-site laboratory support to guide the excavation in order to remove all readilyidentifiable 226Ra contamination. Additional excavation would have been increasingly difficult because it would have involved detecting ever smaller differences between contaminated soil and background in near real time. The probability of excavating and disposing of clean soil would have increased with each successive lift The benefits in terms of reduced dose and risk would have been minimal. Therefore, the levels of residual radioactivity at this site are as low as reasonably achievable. A reasonable effort has been made to remove the residual radioactive contamination from this site. For these reasons, the Air Force Real Property Agency believes that this site is suitable for release for unrestricted use, and is using this FSSR to request removal of the Dudley Blvd site from the US Air Force Radioisotope Committee, Permit #CA-00366-00/02 .

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1.0 INTRODUCTION AND BACKGROUND



This Final Status Survey Report (FSSR) describes the results of the Final Status Survey (FSS) of the former McClellan Air Force Base (McClellan) Dudley Blvd site. Radiological data was collected and analyzed in accordance with the Final Status Survey Plan. Field Sampling Plan, Dudley Radiological Removal Action (September 2011) (FSSP) to demonstrate compliance with the criteria for unrestricted radiological release of the excavated area using Air Force Instruction AFt 40 -201 and following Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) guidance.

The FSSP describes the radioactive emissions from Radium 226 (226Ra), the cleanup criteria, the final status survey design, and the methods used to demonstrate that the criteria have been met following the removal actions.

Radiological data was collected and analyzed for the purpose of collecting sufficient data to satisfy Air Force Instruction AFI-40-201, Managing Radioactive Materials in the US Air Force for unrestricted radiological release of the Dudley Blvd site.

Major Alan Hale with the United States Air Force School of Aerospace Medicine/Radiation Health Branch (USFAM/OEHH) visited the site during the week of September 26, 2011. The purpose of his visit was to provide oversight and independent evaluation of the field removal action and final status survey activities. In Major Hale's report he concludes that; "While the task was completed as requested, unfortunately the independent measurements were unable to be taken after complete remediation. Therefore, the measurements represented in this (subject Site Visit Report) should not be used for potential unrestricted release of the site by the Radioisotope Committee Secretariat; rather, the post remediation measurements taken by the contractor should be used as the criteria for potential unrestricted release of the site. However, observations of the remediation and survey work indicate the contractor was fully competent addressing the radiological conditions at the Dudley Boulevard site." Major Hale's report is presented in its entirety in Appendix L.

This FSSR includes the radiological data collected in support of the FSS. It does not include the data collected during remediation because this data is no longer valid and it does not support an assessment of the final site conditions. Therefore, this FSSR describes the release criteria, data quality objectives (DQOs) and survey design in Sections 2.0 through 4.0, respectively. Section 5.0 presents the final data evaluation and Section 6.0 is the conclusion, followed by_Section 7.0, References, and appendices.

1.1 Site Description

The Dudley Blvd site is located in OU A. The Dudley Blvd site is included in the US Air Force Radioisotope Committee (RIC), Permit #CA-00366-00/02 to authorize the remediation of the radium-226 (226Ra) contamination. This site is approximately 10,760 square ft and is southwest of Dudley Blvd and Dudley Loop. Previous investigations indicated the presence of radiological contamination. Although the source of the radiological contamination is not known, it is suspected that the area stored radium dials, radium waste, or radium paint. The Dudley Blvd site is at the entrance of a motor pool and at the end of a railroad spur, suggesting a vehicle transporting liquid or a railcar loading/unloading liquid may have caused the release. Based on extensive sampling that was done in support of the 2011 removal action (described in this FSSR), it appears that a larger spill occurred, and that the spilled material penetrated into the soil column and then migrated laterally through coarse-grained sands and gravels associated with the former railroad spur (i.e., railroad ballast). The site has a combination cover of asphalt and gravel. The site has been fenced to prevent access since 1996. Figure 1 presents the Dudley Blvd site and removal action boundaries that were accomplished during this 2011 removal action and FSS. Table 1 presents the boundary point location coordinates. All coordinates presented in this report are California State Plane Zone 2, feet.

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TABLE 1. REMOVAL ACTION AND SU BOUNDARY POINT LOCATIONS

BOUNDARY REFERENCE

LOCATION EAsllNG NORTHING

a 2172473.10 358526.32

b 2172482.31 358520.30

c 2172474.94 358509.04

d 2172480.88 358507.00

e 2172481.26 358485.01

f 2172472.81 358482.97

g 2172460.12 358466.23

h 2172458.97 358462.02

i 2172460.91 358448.27

j 2172460.98 358361.45

k 2172439.31 358361.40

I 2172439.13 358447.15

m 2172434.66 358454.36

n 2172433.23 358477.00

0 2172431.54 358487.00

p 2172437.09 358500.19

q 2172443.66 358510.04

r 2172451.42 358515.74

s 2172464.20 358512.72

1.2 Site History

Surface spills had radiologically affected the Dudley Blvd site. 226Ra contamination had been detected in both soil and in asphalt samples on the northwestern corner of the site. In 1997, about 8 cubic yards of soil were excavated from the site and disposed of offsite. The final removal action at this site is documented in this FSSR

1.3 Radionuclide of Concern

The radionuclide of concern for Dudley Blvd was 226Ra, 226Ra used in the maintenance of radioluminescent instrument dials and in the storage of those materials.

The radiological properties of 226Ra and its daughters are important for measurement and detection.

Principle Emissions and Energies (Abundance) Nuclide Half-life Alpha (MeV) 226Ra 1600 y 4.78 (94.5%) 222Rn 3.82 d 5.49 (99.9%) 21BPo 3.05 m 6.00 (99.9%) 214Pb 26.8 m

214Bi 19.9m

Beta (keV)

672 (48.0%) 729 ( 42.5%) 1505 (17.7%) 1540 (17.9%) 3270 (17.2%)

Gamma (keV) 186 (3.2%)

295 (19.2%) 352 (37.2%) 609 (46.3%) 1120 (15.1%) 1764 (15.8%)

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z14p0 zlOpb

2108i ZlOPo

164JlS 22.3 y

5.01 d 138.4 d

2.0 RELEASE CRITERIA

7.69 (99.9%)

5.30 (99.9%)



16.5 (80.2%) 63.0 (19.8%) 1161 (99.9%)

The objective of the field sampling effort was to gather sufficient data to support the unconditional radiological release of the Dudley Blvd site.

For soils associated with the removal action, gamma surveys, direct measurments, and soil samples were taken and quantitatively analyzed and activity concentrations assessed for comparison with the established . Derived Concentration Guideline Limits (DCGLs).

For potentially contaminated objects encountered during excavation, surface release limits were set in accordance with United States Nuclear Regulatory Commission (NRC) Regulatory Guide 1.86.

Removal action objectives (RAOs) for Dudley Blvd are as follows:

• For protection cif human health, prevent exposure to 226Ra in soil and associated ionizing radiation by reducing the average 226Ra concentration, including background, to less than or equal to 2.0 pCi/g The cleanup level for 226Ra (2 pCifg) is consistent with the philosophy of A LARA and will allow for unrestricted release.

• Complete any actions in a manner consistent with protection of human health and to obtain unrestricted release of the site for 226Ra .

• Reduce .the potential for transport of 226Ra contamination present within surface soils to offsite receptors via air and surface water pathways.

2.1 Soils Cleanup Criteria

A background study included sampling and analysis of 129 soil samples. For the combined undisturbed soil set the average 226Ra concentration was 0.568 pCi/g with a standard deviation of 0.122. The 95th percentile Upper Confidence Level (UCL) of the background con-centration distribution was determined to be 0.78 pCi/g of226Ra. Using default parameter values, the United States Environmental Protection Agency (EPA) PRG calculator determined that a risk of 10-4 was equivalent to 1.21 pCi/g of 226Ra. Background plus a risk estimate of 10·4 totaled 1.99 pCi/g of 226Ra. This was rounded to a cleanup level of2 pCifg. (US Air Force 2010).

ISOTOPE

2

To facilitatetransfer of the property from the Air Force to Sacramento County (who will in turn transfer the property to McClellan Business Park), the removal action release criteria must result in residual 226Ra concentration in soil to be suitablefor unrestricted release of the site. The cleanup level for 226Ra of 2.0 pCi/g (inclusive of background) was selected.

2.2 Surface Contamination Criteria

NRC Regulatory Guide 1.86 establishes screening values for radiological contamination on surfac_es. The most _conservative of the specific values listed for alpha and beta surface contamination limits were chosen·for implementation of this plan. These limits are applied to any debris or objects which may be encountered, e.g . asphalt, concrete, tools, pipe lines, tanks, etc.

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lsoTOP£

zz&Rab

DCGL Selected for Project

AlPHA

ToTAL REMOVABLE TOTAL

(DPM/100 CM2)A (DPM/100 CM2

) (DPM/100 CM2)

lOOc 20<

100 20 Notes: • dpm/1 00 cm2- Disintegrmons per minute per 100 square centimeters b NRC RegrJalofy Guide 1.86

5,000



BETA/GAMMA

REMOVABLE

(DPM/100 CM2)

1,000

• . Measured alpha values wiU be adjusted to account for 3 alphas per decay prior to comparison with the release Umit.

2.3 Action Levels/Criteria Application

Action levels are numerical values established to cause the decision maker to choose between alternative actions. The decision statements and alternative actions for this FSS are discussed in Section 3.1. The action level for soils and surfaces is discussed in Sections 2.1 and 2.2 respectively.

The acceptance criteria were applied as follows in regards to soil samples: If the difference between largest survey unit measurement and smallest reference area measurement is less than DCGLw. the survey unit meets criterion. If the difference between the survey unit average and reference area average is greater than DCGLw. the survey unit does not meet criterion If the difference between any survey unit measurement and any reference area measurement is greater than DCGLw AND the difference of survey unit average and reference area average is less than DCGLw. conduct WRS Test and elevated measurement comparison .

The acceptance criteria were applied as follows in regards to surface contamination on objects remaining at site (ex: telephone pole):

• If any single measurement on a surface exceeded the surface contamination criteria, perform surface decontamination and/or material removal.

• If all ofthe measurements on a surface are less than the surface contamination criteria, the surface meets criteria for release.

3.0 DATA QUALITY OBJECTIVES AND SURVEY DESIGN

The DQOs are qualitative and quantitative statements that establish a systematic procedure for defining the design by which data collection criteria are satisfied in order to make determinations regarding remediated properties.

3.1 Project Data Quality Objectives

The DQO process consists of the following steps:

1. State the Problem 2. Identify the Decision 3. Identify Inputs to the Decision 4. Define the Study Boundaries 5. Develop a Decision Rule 6. Define Decision Errors 7. Optimize Survey Design

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3.1.1 Step 1 - State the Problem



Radium was used at McClellan and has impacted the Dudley Blvd site that is planned for remediation and release for unrestricted use. Any surface contaminated objects that may be encountered will be assessed based upon NRC Regulatory Guide 1.86. The objective is to obtain data of sufficient quality and quantity to support unrestricted release of these sites, i.e. 2 pCi/g residual226Ra in soils and surface contamination measurements less than the limits prescribed in NRC Regulatory Guide 1.86.

3.1.2 Step 2 - Identify the Decision

Do the remaining soil concentrations and for object surfaces exceed applicable levels for unrestricted release following remediation?

Alternative Actions

The following alternative actions will result from resolution of the principle study question:

• If statistically evaluated residual radiological contamination does not exceed the applicable release criteriajDCGL levels listed in Section 2.0 of this document, the land areas will be recommended for unrestricted release.

• If statistically evaluated residual radiological contamination exceeds the applicable release criteriajDCGL levels listed in Section 2.0 ofthis document, SUs exceeding these levels will be identified and designated for additional characterization andjor remediation.

3.1.3 Step 3- Identify Inputs to the Decision

This section lists the data needs, describes the sources of that data, and discusses the means of obtaining the required data.

Since radium is a naturally occurring radionuclide, the background must be compared to the observed levels. Specifically, as noted in Section D.S of MARSSIM, "If the difference between the mean concentration in the survey unit and the mean concentration in the reference area is less than the investigation level, then the survey unit is in compliance with the release criterion." (DOD 2000) To implement the decision rule, an estimation of the difference is required and may be obtained by measuring the radionuclide concentration at sufficient randomly selected points in the survey unit and reference area. This analysis was performed by the Air Force (USAF 2010).

Concentrations of residual RAM in the soil and asphalt areas remaining at each site will be determined by means of the following:

• Gamma radiation walkover surveys • Direct measurement surveys at designated sample locations • Sampling and gamma spectroscopy analysis for 226Ra

Gamma Radiation Surveys and Gamma Spectrometry

·Remediated land, concrete and asphalt areas associated with Dudley Blvd will be scanned with 2 x 2 inch Nal (TI) gamma scintillation detectors. Screening levels will be determined based upon the background c:;ount rate plus three standard deviations. Areas that exceed the screening levels should be bound by additional survey and may be selected for sample collection and analysis in addition to the systematic samples already planned for each SU. Areas less than the screening level will be subject to the systematic sampling as presented in this plan and in accordance with MARSSIM guidance and analyzed by on-site gamma spectrometry.

Concentrations of residual RAM on surfaces will be determined by means of the following:

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Direct frisk for total alpha radiation Direct frisk for total beta/gamma radiation ,



• Smear sampling for transferrable alpha and betajgamma radiation

Surface Alpha and Beta Radiation Scans

Surfaces of objects that may be encountered during excavation, such as buried pipelines and tanks, will be scanned 100% for alpha and beta/gamma emitting radiation. Static counts and smear samples will also be collected and analyzed for gross alpha and beta/gamma radiation at locations with elevated readings during the surface scan and/ or at locations determined by professional judgment in the field. In the absence of scan data indicating elevated readings, static count and smear locations should be selected that represent worst case conditions, e.g. pinch points, junctions, areas of discoloration, or other areas that may be expected to trap or hold contaminated material.

3.1.4 Step 4- Define the Study Boundaries

Study boundary decisions are defined relative to the areas targeted for removal action and associated SU boundaries. The areas targeted for remediation and the resulting SU boundary are presented in Figure 1,.Final Status Survey Plan Field Sampling Plan (Environmental Dimensions, inc. 2011).

3.1.5 Step 5- Develop a Decision Rule

A separate decision will be made for each SU as to its acceptability for release. All SUs within a given site shall be assessed separately and in accordance with the FSSP, Section 11.6, Statistical Tests, and in consideration of the applicable soils DCGL. The SU must pass for release before a recommendation to release the site for unrestricted use can be made .

Surface contamination limits per. NRC Regulatory Guide 1.86 are used for surfaces and/or objects that may be encountered. If areas of radioactivity exceed the release criteria for surface contamination, the identified areas will be segregated as either waste or candidates for decontamination and/or removal.

3.1.6 Step 6- Define Decision Errors

While the possibility of decision error cannot.be totally eliminated, it can be controlled by collecting a larger number of samples and/or using more precise measurement techniques. Hypothesis testing is used to control the probability of making decision errors. For this project the null hypothesis uses scenario A. The survey unit does not meet the release criterion. "A Type I decision error occurs when the null hypothesis is rejected when it is true, and is sometimes referred to as a false positive error." "A Type II decision error occurs when the null hypothesis is accepted when it is false. This is sometimes referred to as a false negative error." (EPA 2000). For this project, the Type I error has been set at 0.05 and the Type II is set at 0.05. As such,

• the probability of incorrectly releasing a survey unit in which the residual radioactivity exceeds the DCGL does not exceed 5%; and

• the probability of rejecting a survey unit which does achieve the DCGL is also set at 5%.

3.1. 7 Step 7 - Optimize Survey Design

A substantial amount of previous survey and sampling and analysis data have provided detailed information on the nature and extent of residual contamination. This FSSR describes the additional post-removal action surveys, measurements, and sample and analysis data required to assess the nature and extent of post-removal action residual activity.

The SU design considered the size and proximity ofthe subject Target Areas (TA) as well as balancing efficient field operations and final reporting with sufficient and appropriate data collection for each,

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i.e. focusing on the remediated TA's. SU were designed to minimize the number of survey units while meeting the data collection requirements. Current TA boundaries were approximate pending preexcavation sampling. As such, SU dimensions and·locations are also approximate. SU boundaries are planned to be approximately five feet from the remediated area at the closest point.

Only one SU is planned for this project, i.e., SUl. The intent of SU 1 is to capture the entire remedial action footprint.

SUs currently identified with TA removal actions are Class 1 (see Section 12.0, Land Area Site Survey Unit Designations).

The sampling and measurement design process was based upon the collection of systematic samples and measurements at the prescribed quantity from the SU using a random start triangular grid for the Class 1 area and used the mathematical approach defined in MARSSlM Equation 5-7 for spacing of measurements.

Classes

The definition and designation of survey units is based primarily on the area classification, survey unit size, DCGL, and background and the variability of the contamination concentrations. Minimum required scan survey coverage is in turn dependent on the area classification of the survey unit This paragraph provides the basis for classification of survey units and the selection of measurement locations to optimize surveys. There are no Class 2 or Class 3 survey units for the Dudley Blvd site.

A survey unit is classified as a Class 1 survey unit if it meets any one of the following criteria:

• The area is or was impacted (potentially influenced by contamination); • The area has potential for delivering a dose or risk above criteria; • There is potential for small areas of elevated activity; or • There is insufficient evidence to classify the area as Class 2 or Class 3.

The recommended surface areas for Class 1 Survey Units (from MARSSIM "Suggested SU Areas" EPA 2000):

Cl.AssiACAnON

Class 1

SUGGESTED AREA

Structure: up to 100 square meters (m 2) [900 square ft (ft2

)]

Land Area: up to 2,000 m2 [18,000 ft2]

Relative Shift for Surface Measurements

The relative shift is defined as the l:ljcr where~ is the DCGLw·- LBGR (lower bound of the gray region) and cr is the standard deviation of the contaminant distribution. MARSSIM recommends that the LBGR initially be set at one-half of the DCGLw. but should be adjustec;i if necessary to provide a ~/cr value between the recommended range of 1 to 3.

The value for cr can be estimated in a number of ways. Data from the site may be sufficient to calculate the standard deviation within the survey unit, crs (note that for Class 1 units cr represents the standard deviation just prior to release and after material above the criterion is thought to be removed). Data is also available from a reference or background area. Reference area data can be used to estimate a standard deviation, crr, if the contaminant is present in background. The larger of the two cr values, i.e. cr5 and cr., should be used when calculating ~/cr.

Given that limited data exists for parts of the survey areas consistent with MARSSSIM, "it may be reasonable to assume a coefficient of variance on the order of 30%, i.e., 0.3, based on experience."

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(EPA 2000). Experience implementing MARSSIM has demonstrated that this is a reasonable assumption.

Calculating the Relative Shift

Given that the Dudley site is industrialized, i.e. not in a native undisturbed soils condition, it is assumed that the actual standard deviation of a resulting data set will be higher. The presence of non-native fill, bedding material, and finishes can be expected to provide a wider variation in analytical and measurement results. Therefore, the Relative Shift is calculated using an assumed standard deviation (cr) of30% per MARSSIM direction and determined reasonable from professional experience.

Relative Shift for Land Areas

The Relative Shift is defined as the 11/cr where 11 is the DCGL- LBGR (lower bound of the gray region) and a is the standard deviation of the contaminant distribution. MARSSIM recommends that the LBG R initially be set to one half of the DCGL, but should be adjusted if necessary to provide a 11/cr value between the recommended range of 1 to 3.

The value for a can be estimated in a number of ways. Sometimes there is data from the site that is sufficient to calCulate the standard deviation within the survey unit, crs (note that for Class 1 SUs cr represents the standard deviation just prior to release and after material above the criterion is thought to be removed). Data may also be available from a reference or background area. Reference area data can be used to estimate a standard deviation, O"r, if the contaminant is present in background. According to the Revised Reference Area Final Status Survey Report (McCiellanAR #5777) the standard deviation for 226Ra in background soils is 0.122. The larger of the estimated crs and O"r should be used when calculating 11/cr. ·

For the subject project sufficient representative data of known pedigree have not been obtained. Past experience implementing MARSSIM, in consideration of the analytical technique employed, has demonstrated that an estimate for O"s of 0.3 pCi/g is a reasonable assumption. Since an estimated O"s of 0.3 pCi/g is greater than O"r (0.122 pCi/g), a will be assigned a value of 0.3 pCi/g. Additionally, using a larger standard deviation will result in a more conservative number of samples, i.e. higher number of samples required for final status determination. · ·

The Relative Shift is then calculated given values for the DCGL. LBGR, and cr. As previously discussed, the DCGL has been set at 1.2 pCi/g. The LBGR is then calculated as half of the DCGL, or 0.6 pCi/g. The value for 11 is, therefore, DCGL- LBGR = 1.2- 0.6 = 0.6 pCi/g. Using the estimated value for a the Relative shift can be calculated as (0.6 pCi/g)/(0.3 pCi/g) = 2.0. Given that MARSSIM recommends a Relative Shift between 1.0 and 3.0, no adjustment is necessary.

Number of Sample/Measurement Locations per Land Area Survey Unit

From MARSSIM Table 5.3, a Relative Shift of 2.0 with 0.05 Type I error and 0.05 Type II Error has an N/2 = 13 samples per SU.

Land Area Reference Grids

The Class 1 survey unit grids for Dudley Blvd are calculated as follows:

For Class 1 triangular grids: L = {(407 m2f (0.,866 x 13)}1/2 = 6.01 m For Class 1 square grids: L = ( 407 m2/13)1/2 = 5.59 m

Survey Approach For Surface Measurements

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Surveys of surface contaminated objects are dependent upon the size and potential use scenarios of the objects. Each object was scanned with hand held instrumentation for alpha and beta/gamma radiation. Smear samples were collected either randomly and/or in conjunction with professional judgment. The resulting data was evaluated against the surface release criteria specified in NRC Regulatory Guide 1.86. If the surface measurements exceeded the release criteria the objects were either decontaminated or disposed of as waste.

Remediated land, concrete and asphalt areas associated with Dudley Blvd were scanned with 2 x 2 inch Nal (Tl) gamma scintillation detectors. Screening levels were determined based upon the background count rate plus three standard deviations. Areas that exceeded the screening levels were bound by additional survey and were selected for sample collection and analysis in addition to the systematic samples. Areas less than the screening level were subject to the systematic sampling in accordance with MARSSIM guidance and analyzed by on-site gamma spectrometry.

The sections below present the Survey Unit for this FSSR

SITE SU OASSIFICATION RA TARGET ARfA(S) APPROXIMATE SU AREA

Dudley Blvd. SU1 Class 1 1, 2, 3, and4 411 m1

The single survey unit is Class I and has confirmed radiological contamination above release criteria.

Table 2 presents location identification and GPS coordinates for locations representing the systematic sample locations for the final status sampling .

TABLE Z. DUDLEY SURVEY UNIT SYSTEMATIC SAMPLE LOCATION COORDINATES

l.ocA110N ID NolmiNG" EAsnNG"

S'fSTEMAnc: SAMPlE l.ocAllONS SU1-101 358369.0705 2172444.857

SU1-102 358385.9811 2172454.620

SU1-103 358402.8917 2172444.857

SU1-104 358419.8024 2172454.620

SU1-105 358436.7130 2172444.857

SU1-106 358453.6237 2172454.620

SU1-107 358470.5343 2172444.857

SU1-108 358487.4450 2172435.093

SU1-109 358487.4450 2172454.620

SU1-110 358487.4450 2172474.147

SU1-111 358504.3556 2172444.857

SU1-112 358504.3556 2172464.384

SU1-113 358521.2663 2172474.147

a California State Plane Zone 2, feet

Concentrations of residual RAM on surfaces will be determined by means of the following:

• Direct frisk for total alpha radiation • Direct frisk for total beta/gamma radiation • Smear sampling for transferrable alpha and beta/gamma radiation

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4.0

3.1.8 Deviations from the Survey Design



Although the site conceptual model remained unchanged the affected area was larger than originally anticipated. The excavation, originally planned as four smaller excavations extending over an area of approximately 2,000 square feet (186 square meters) and to a depth of 1.5 feet bgs, became one large excavation area that covered an area of roughly 4,400 square feet ( 400 square meters) and ranged in depth from 1 to 3 feet bgs. The final total volume removed was 120 cubic yard (CY) (90 CY soil, 30 CY asphalt) versus a planned total removal volume of 74 CY (24 CY soil, 50 CY asphalt). The increased excavation was a result of 226Ra contamination being somewhat deeper and to a larger aerial extent than originally anticipated. The final status survey design, however, remained unchanged and was implemented as planned for a single Class 1 SU.

As was planned (CH2M Hill2011), with respect to the onsite laboratory analysis of226Ra, the data were evaluated for the peaks present for all relevant isotopes; 226Ra (186 KeV), 214Bi (609 KeV), and 214Pb (352 KeV). The primary data presented and used in the determinate statistical tests presented in this report are from the analysis of the 609 KeV line associated with the 214Bi daughter in the 226Ra decay chain. While the 186 KeV line from 226Ra was evaluated it was not used for reported data due to the elevated uncertainty and the low frequency of identification. The 226Ra 186 KeV energy line is a low abundance, low energy line and is additionally difficult to resolve in that region of the spectra due to high levels of natural and other isotopic constituents. The analytical protocols employed yielded much more consistent identification of the 214Bi at the 609 KeV energy line. This consistency and the acceptable comparability to the offsite data (as presented in Section 5.0) provide the basis for using the subject analytical results. The final status data presented in Section 5.2 were evaluated multiple ways in order to assess the impact of a potential bias between the onsite and offsite laboratory data. All evaluations yield the same conclusion; the site is suitable for release for unrestricted use in accordance with the RAOs for this site.

FINAL STATUS SURVEY

This section presents a general discussion of the remediation activities followed by the presentation of survey and soil sample collection results. All activities conducted during implementation of the FSS were performed in accordance with the FSSP. General field operations including field work scheduling, staging, and work area security and housekeeping, were performed in accordance with AFI-40-201, Managing Radioactive Materials in the United States Air Force.

4.1 Summary of Remediation Activities

On September 26, 2011, the field crew mobilized the resources necessary to efficiently perform and complete the removal action and field screening tasks at the Dudley Blvd site for an anticipated duration of two days. Excavations were performed at each target area and the material was direct-loaded into roll off bins which were subsequently loaded onto trucks for transport and disposal. Initially, excavation at each area was to the planned depths and areal extents within four distinct areas covering a total of 1,614 sf, with depths ranging from 0.5 to 1.5 feet bgs. The contamination in asphalt was successfully removed as evidenced by survey results. However, field screening observations and on-site laboratory analytical results identified the need to continue excavation of soil to greater depths and over a larger area. The contamination in soil was determined to be associated with a sand trench containing coarse-grained sands and gravels associated with the former railroad spur (i.e., railroad ballast), rather than isolated spots of contamination in soil underlying the asphalt. Therefore, once the four initial areas were excavated and the sand trench discovered additional 226Ra contamination still existed. A series of multiple excavations (both machine and manual), step-out sampling, surface scans, and sur-Veys were performed and excavation was continued until the readily-

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identifiable contamination was removed. Additionally, elevated readings were discovered to be associated with pieces of old asphalt that had been used to backfill around the base of a telephone pole and at the base of a concrete storm water drainage junction box. Additional excavation was performed to remove remaining pieces of asphalt and additional measurements and samples were collected. The asphalt and soil continued to be direct-loaded onto trucks.

The resulting excavation area was 3,200 square feet (297 square meters) compared to an originally planned excavation area of 2,000 square feet (186 square meters) resulting in a final total volume removed of 120 cubic yard (CY) (90 CY so.il, 30 CY asphalt) versus a planned total removal volume of 74.CY (24 CY soil, 50 CY asphalt). The increased volume was a result of 226 Ra contamination being deeper and more widespread than originally a11ticipated. Excavation that was planned for two days ended up taking 46 days. Overall, the conceptual model for the site of minor surface spills resulting in asphalt and very shallow soil (from 0.5 to 1.5 feet deep) contamination'was found to be valid, however the spilled material penetrated deeper into the soil column and then migrated laterally through coarse-grained sands and gravels associated with the former railroad spur. Additionally, contaminated pieces of old asphalt were used as backfill.

No radioactive waste was generated as a result of this FSSR. All soil was disposed at Clean Harbors, Deer Trails, CO.

A general area air monitoring station was established downwind of the excavation activities to collect fugitive dusts during excavation and load out activities and the occupational Derived Air Concentration (DAC) for zz6Ra (3x1Q·lO uCifml) was not exceeded. .

Once the ZZ6Ra contamination was removed, the site was ready for final status survey. The following section presents detailed information on the general field operations, survey and sampling methods, and survey results from the beginning of the project through the end of final status survey.

4.2 General Field Operations

Commercially available portable hand-held radiation detection and onsite laboratory measurement instrumentation were used for the Dudley Blvd project. A project file was kept on site during the FSS for the instrumentation (e.g. instrument calibration and check sources) used for survey and analytical data collection.

Contamination control measures were incorporated during work area access and egress through the establishment of a personnel access control point. All personnel entered the work area through the access control point and were frisked for radiological contamination prior to egress from the area.

Observation for dust- During the removal action throughout the project all contractor personnel observed for indicators of potential dust hazards. These indicators included visible drying of previously wetted surfaces, activities knowri to cause dust generation (e.g., soil excavation, load out, etc.), or presence of visible dust in the air. Any time that any one of these indicators was observed, the water truck was used to wet the soil surface.

A water truck with a hose attachment was on-site and used for dust control. Overall, there were no substantive observations of visible dust in the air, as described by the monitoring results below.

A general area air monitoring station was established downwind of the excavation activities to collect fugitive dusts during excavation and load out activities in an effort to verify radionuclide dust concentrations were within action levels. In general, the monitor was operated during working hours when weather permitted (e.g., the monitors were not deployed during periods of rain that interfere with or invalidate results). The occupational Derived Air Concentration (DAC) for Z26Ra (3x10·10 uCi/ml) was not exceeded .

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4.2:1 Quality Control



Measurements performed and samples collected for the FSS were performed in accordance with standard QC requirements. Duplicate analyses, sample chain-of-custody (COC), instrument performance checks, control of field survey and laboratory data, and QC assessments provided a high level of confidence in the data collected to support the survey outcome.

4.2.2 Calibration and Maintenance

Instrumentation was maintained to manufacturer's specifications and calibrated for the radiation types and energies of interest using National Institute of Standards and Technology (N 1ST) traceable and or otherwise certified source material. Instrumentation was inspected prior to use to ensure its proper working condition, and properly protected against inclement weather conditions in the field. For the onsite laboratory detector a certified standard reference material was placed in a 1.65 liter Marinelli container to maintain consistency with sample counting geometry. For instrumentation used for release of surfaces in accordance with NRC Regulatory Guide 1.86, a two pi geometry source was used to derive instrument efficiency values for measurement of total alpha and beta contamination.

4.2.3 Daily QC Source Checks

Quality check measurements were performed daily, pre- and post-dat(l collection, for all onsite field and laboratory-based instruments. A consistent, controlled area was used to perform these checks. Both background and check source responses were assessed.

The QC criteria for alpha, beta, and gamma instruments used during daily QC checks were as follows:

• If any single QC check is found to be outside of 2o (Investigation Level),.the measurement is to be repeated.

• If the second count is also found to be outside of 2o, ~e instrument is to be investigated to assess if any external biases or instrument physical damage is present.

• If any single reading is found to be outside of a 3o boundary (Action Level), the instrument must be taken out of service and the situation resolved by the survey supervisor. (Highly fluctuating source or background responses may be due to a bad cable, insufficient gas purge, bad detector tube, or malfunctioning electronics.)

Background and source checks· were documented by the survey supervisor or designee.

All of the instrument QC documentation, including. instrument setup data and daily QC check results/graphs are presented in Appendix B. Instrument calibration certificates are presented in Appendix C.

4.2.4 Detection Sensitivity

Table 3 presents the detection sensitivity for the instruments used during this project. Calibration certificates for all field measurement instrumentation are presented in Appendix C .

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TABLE 3. RADIAnON DETECTION INSTRUMENTATION INVENTORY

INSlRUMENT DErEcroR SERIAL NUMBER APPI.JCATION 0ESCRJP110N

RADIATION AcnvE AREA (CM

2)

No. SENSITlVITY

2-inch by 2-Gamma radiation inch Sodium

1" Ludlum 44-10 185844 scans and static Iodide [Nal)

Gamma N/A Ludlum 2221 183983 measurement with

counts Scaler/Rateme ter 2-inch by 2-

Gamma radiation inch Sodium

2 Ludlum 44-10 0533 scans and static Iodide [Nal]

Gamma N/A Ludlum 2221 117651 measurement with

counts Scaler/Rateme ter

Alpha/Beta Alpha/Beta

Ludlum 43-93 PR199832 radiation 3

Ludlum 2360 177184 surface release

scintillation Alpha, Beta 100

surveys detector.

Ludlum 2929 629

Removable Dual Olannel

4 Ludlum 43-10-184798

Contamination "Phoswich"

Alpha, Beta N/A 1 (smear) Counter

(3-inch by 3-Canberra inch Sodium Model802-

13000938/1300012 Sample Analysis, Iodide

5 3x3/ Canberra 1.65 L Marinelli (Nai))/Osprey Gamma N/A Model Osprey-

3 geometry MCA/Laptop w

DTB Genie 2000 Software

• Backup mstrument, not used dunng final status survey.

Detection Sensitivity- Static Scans And Minimum Detectable Concentrations

The minimum detectable concentration is an activity level, calculated a priori "before-the-fact", that a specific instrument and measurement technique can be expected to detect 95 percent of the time. Site-specific detection sensitivities (MDCs) have been calculated in accordance with the approach detailed in NUREG-1507, Minimum Detectable Concentrations with 'l)tpical Radiation Survey Instruments for Various Contaminants and Field Conditions (NRC 1998), and NUREG-1575, MARSSJM (DOD 2002).

The sections below detail the approach for calculating MDCs for individual instruments that may be used in the final status survey process.

Determination Of Instrument Response For Alpha And Beta Surface Activity Measurements

The instrument efficiency (Ei) used to calculate the MDCs to be used is based upon instrument characteristics at similar sites and will be re-calculated if necessary at the initiation of the survey and assessment of the initial data.

Static MDC

The static MDC for surfaces may be calculated as follows:

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Where: B =background count rate (cpm) Es = surface efficiency E1 = instrument efficiency Tg =sample count time (min) Tb =background count time (min)



Appendix 8 presents a worksheet for a specific instrument to provide an example of calculated MDCs for a variety of background levels. The example calculations below use the following conditions:

• Alpha - 10 background counts with 5 minute background and sample count times • Beta- 1000 background counts with 5 minute background and sample count times

Surface Efficiency (Es) For Surface Activity Measurements

Surface efficiency is referred to interchangeably as source efficiency or surface efficiency in MARSSIM and NUREG-1507.

MARSSIM notes on page 6-25, that "A source efficiency of 0.5 is recommended for beta emitters with maximum energies above 0.4 Mega electron-Volt (MeV). Alpha emitters and beta emitters with maximum beta energies between 0.15 and 0.4 MeV have a recommended source efficiency of0.25." (EPA 2000).

Probe Area Correction Factor For Surface Activity Measurements

Since contamination reporting for survey results is specified in dpm/100 cm2 a probe area correction factor is required for,all instruments with a probe area greater or less than 100 cm2• The correction factor is calculated as follows.

. (probe area) Correction Factor= 2 100 em

Calculation Of Static MDC For Alpha Surveys (100 cm2 Probe)

The alpha static MDC for the Ludlum Model43-93 detector can be calculated as follows:

Background= 2 cpm Tb = 5 minutes T g = 5 minutes Es = 0.25 E1 = 0.186 cpm/dpm Probe area = 100 cmz

( 3 + 3.29 (2)(5) (1 + ~)) MDC= (100 cm2 )

(0.25)(0.186) 100 cm2 (5)

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MDC= 76 dpmj100 cmz



For alpha survey instrumentation with a background of approximately one to three counts per minute, a single count will give a surveyor sufficient cause to stop and investigate further. Assuming this to be true, the probability of detecting given levels of alpha emitting radionuclides can be calculated by use of Poisson summation statistics. Derivation of this equation can be found in Appendix J of MARSSIM.

The actual background values are unavailable. The MDCs may be re-calculated utilizing site-specific background levels determined on-site.

Calculation of Static MDC for Beta Surveys (100 cm2 Probe)

The beta static MDC for the Ludlum Model43-93 detector can be calculated as follows:

B= 200 cpm Tb = 5 minutes Tg = 5 minutes Es = 0.5 E1 = 0.37 cpmfdpm Probe area= 100 cmz

( 3 + 3.29 Jc2o0)(5)(1 + ~)) MDC= (100 cm2 )

(0.5)(0.37) 100 cmz (5)

MDC =·162 dpm/100 cmz

Scanning Minimum Detectable Count Rate (MDCR)

The minimum detectable number of net source counts (MDCR) in the interval is given by s,. Therefore, for an ideal observer, the number of source·counts required for a specified level of performance can be arrived at by multiplying the square root of the number of background counts by the detectability value associated with the desired performance (d) as shown below:

s, = d 1 .jb, or

s, =minimum detectable number of net source counts d' = index of detectability 8 =background count rate (cpm)

The observation interval (I) is defined as the width of the probe divided by the time that 25% of the probe is over a 4"x4" area of interest (scan speed).

i= (probe width) f (scan speed) or

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i =observation interval (sec) w =probe width (in)

w i =

s

The observable background counts (b,) are defined, as the number of background counts that occur during an observation interval.

b, = (B) X (i/60)

The MDCR is defined as the increase above background recognizable during a survey in a given period of time. The variable, d', is defined as the index of detectability and is dependent on the selected decision errors for Type I (alpha) and Type II (beta) errors. A true positive error (1-P) of95o/o and a false positive error (alpha) of 5 o/o were selected. The value of3.28 for d'was obtained from Table 6.5 in MARSSIM.

MDCR = s,x (60/i) = cpm

,,

Determination of MDCR and Use of Surveyor Efficiency (Beta, 100 cm2 probe)

Using the same parameters from about the beta MDCR for the 43-93 can be calculated as follows:

w = 3.5 in s= 2 in./ sec 8 = 200 cpm d' = 3.28 (table value) i = (3.5 in/2 in/sec)= 1.75 sec bi = 200 cpm x (1.75 sec/60 sec)= 5.83 counts in two seconds Si = 3.28 x (5.83)112 = 7.92 counts MDCR = 7.92 x (60/1.75) = 272 cpm

Applying the survey efficiency ofO.S: MCDRsurveyor = Ssurveyor, i = (3.28 x (5.83)112)/ (0.5)112 = 384 cpm

Determination of MDCR and Use of Surveyor Efficiency (Alpha, 100 cm2 probe)

The alpha MDCR for the 43-93 can be calculated as follows:

w = 3.5 in s = 2 in/sec 8 = 2 cpm d' = 3.28 (table value) i = (3.5 in/2 in/sec)= 1.75 sec b, = 2 cpm x (1.75 sec/60 sec)= 0.06 counts in two seconds S, = 3.28 x (0.06)1/2 = 0.8 counts MDCR = 0.8 x (60/1.75) = 27 cpm

Applying the survey efficiency of 0.5: MCDRsurveyor = Ssurveyor,l = (3.28 X (0.06)112)/ (0.5)112 = 38 cpm

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4.3 Determination of Scan MDC (Nal 2x2)



In accordance with MARSSIM, Chapter 6, Table 6-7 an a priori Scan MDC for 226Ra in soils using a 2x2 Nal gamma detector can be estimated at 2.81 pCi/g. It should be noted that it is not reasonably achievable to reliably convert gross field measurements to pCi/g results in an industrialized setting such as Dudley. This is especially so at the low limit of 2 pCi/g 226Ra where the increase in counts at or near these concentrations from the 226Ra is somewhat lost in the variation of both the site and background reference area gross measurement data. While the FSSP (CH2M Hill2011) acknowledged that the static and scan MDCs for 226Ra may be above the site release criteria of 2 pCijg and that the gamma survey may be unable to measure 226Ra at release levels with the 2X2 Nal detector, the gamma survey was only intended to provide screening level data. Upon completion of the walkover gamma survey the data were evaluated. Statistics were generated from the walkover data set, see Section 4.5, and evaluated as follows: comparison to the reference area walkover data, locations falling within two to three standard deviations were investigated, and locations falling outsii:le of three sigma were sampled and considered for EMC evaluation and/or additional remediation. Four additional biased soil samples were collected following the evaluation of the walkover gamma survey. These samples are presented in Table 6 of this FSSR and designated by "-8" following the sample id. It should be noted that while these locations did fall outside of the two and three sigma investigation levels, the highest analytical result was 2.21 pCi/g 226Ra; all others were reported as less than 1.0 pCifg 226,Ra. While the 2x2 Nal gamma detectors used for the walkover gamma surveys may not be sufficient to release any site at the 2 pCijg 226 Ra level, this performance based evaluation for this site indicates that the achieved Scan MDC is reasonably close to the a priori Scan MDC presented above and is sufficient to be used as planned.

4.4 Total Uncertainty Error (TUE)

Determining the Total Uncertainty Error (TUE) of the output estimate/measurement requires that the uncertainties of all the individual input estimates/measurements be determined and expressed in comparable forms. Due to the randomness of radiological decay events of both the target source and background' environments, as well as the potentially large variance in the magnitude of individual measurements, make estimating the total uncertainty in individual andjor groups of measurements somewhat complex. However, estimates ofTUE can be made on a performance basis by assessing measurement performance of sets of repeated measurements and in consideration of input measurement variability where uncertainty is better defined such as weights, volumes, certified standards, etc. The sections below briefly discuss the TUE associated with the field measurements (surface and walkover surveys) and laboratory analyses (soil samples) presented in this report, as well as provide an estimate of TUE for each.

4.4.1 Surface and Walkover Surveys

Surface surveys involve static and scanning measurements made with handheld field instruments. Gamma walkover surveys use field instrumentation for scanning, i.e. walkover of land areas. All of these instruments provide a direct measurement read out in counts per minute (cpm). Daily performance verification of these instruments is achieved by the initial measurement of a certified source of known value and the background. Both of these measurements are made atthe beginning and end of each day in a consistent, stable environment. Performance is assessed by comparing the daily instrument responses to both the source and background against control limits established by a series of repeated measurements made prior to using the instrument in the field. Daily measurements are determined to be in control and acceptable if they fall within+/- 2 standard deviations of the established control limits and are also evaluated for trends. Additionally, instrument efficiencies are verified against the calibrated efficiency and should fall within + f- 20%. Sources of uncertainty include systematic errors such as the uncertainties associated with the known source value (- 5%) and the calculated efficiency of the instrument ( -5%). Radom errors include operator variances, the fundamental unit of measurement, i.e. radioactive decay events, and instrument voltage variations .

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A simplified TUE analysis has been performed in accordance with the Guide to the Expression of Uncertainty Measurement (GUM) published by the International Organization for Standardization. Appendix N presents a printout of the model parameters and function used for both the alpha and beta error analysis. The parameters used were not all inclusive but do represent the major sources of quantifiable analytical error for the subject measurements. Actual sample data were utilized for the calculation of the TUE. Sample measurements reported by GUM and manual calculations were as expected and comparable; alpha measurement results were both 32 dpm/100cm2 and beta measurements were also the same at 82 dpm/100cm2. GUM methodology resulted in a TUE of 7.66 dpm/100cm2alpha measurements ( -24%) and 28.7 dpm/100cm2 (-35%) for the beta.

4.4.2 Onsite Laboratory

Soil samples are analyzed using a lead shielded 3x3 Nal detector connected to a laptop computer running the Canberra Genie 2000 software. This equipment is non-portable and will be set up in a fixed location. The detection system produces results in pCi/g of sample analyzed. The instrument is initially calibrated for both energy and efficiency against a certified reference material with an uncertainty of approximately+/- 5%. A second certified source is used for the daily verification of both energy and efficiency. The acceptance criteria for the daily verification analyses is +I- 10% of target isotopes present and accounts for both the qualitative identification (energy verification) and the quantitative reporting (efficiency verification). Sources of uncertainty include systematic errors such as the uncertainties associated with the known source value (- 5%), the calculated efficiency ( +/· 5%) and the calibrated energy ( +/· 1 o/o) of the detection system. Additionally, samples are weighed on a calibrated balance and verified with pre- and post-work day measurements of a certified reference required to be+/· 1 o/o. Radom error primarily consists of the fundamental unit of measurement, i.e. radioactive decay events .

A simplified TUE analysis has been performed for the onsite lab data in accordance with GUM. Appendix N presents a printout of the model parameters and function used. Sample concentrations reported by GUM and the system software were as expected and comparable at 1.392 and 1.384 pCi/g respectively. GUM methodology resulted in a TUE of 0.097 pCifg compared to a CU of 0.069 pCi/g, representing a TUE approximately 40% greater than the CU alone and representing and approximately 7% TUE for the system. Table 4 presents a summary of the performance specifications used during the subject final status survey activities.

TABLE 4. SUMMARY OF FSS INSTRUMENT PERFORMANCE SPECIFICATIONS

I>ETEcroR APPucAnoN EsnMATfOFTUE MDC/A MDCRsu....,oa ScAN MDC

Ludlum 44-10 Gamma radiation

Ludlum 2221 scans and static +/-20% NA NA 2.8 p0/g1

measurement counts Alpha: 71

Ludlum 43-93 Alpha/Beta surface +/-20%

dpm/100cm2 Alpha: 38 cpm NA

Ludlum 2360 release surveys Beta: 260 Beta: 384 cpm dpm/100cm2

Counting Uncertainty at 2a +

Avg. MDAs: Canberra Model 10% 214ai: +/- 0.40 pCi/g 802-3x3/ Sample Analysis, 1.65 Avg. TUEs: 214

Pb: +/- 0.30 pCi/g NA NA Canberra Model L Marinelli geometry 214Bi: +/- 0.12 pCi/g 226Ra: +/- 2.4 pO/g Osprey-DTB 214Pb: +/- 0.12 pCi/g

226Ra: +/- 0.67 pCi/g

tin accordance w1th MARSSIM, Chapter 6, Table 6-7 an a pnon Scan MDC for 226Ra m soils

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4.5 Survey and Sampling Methods

Final Status Survey Report Dudley Blvd Radiological Removal Act1on


Survey and sampling activities were conducted for both land areas, i.e. the excavation footprint defining SU1 and for feature surfaces within the excavation footprint, i.e. an iron utility manhole, a.concrete utility box servicing a telephone pole, the telephone pole, and a concrete utility box servicing the storm water sewer syste~. For land areas, data was collected following the standard MARSSIM approach to include:

1. 100% Gamma Walkover Survey 2. Static Measurements 3. Sampling and Analysis

Gamma Walkover Surveys- Walkover surveys were performed over 100% of the SU using a columnated, i.e. shielded, Ludlum Model44-10 2 x 2 Nai(TI) Gamma scintillation detector connected to a Ludlum Model 2221 ScalerjRatemeter equipped with a RS 232 data output coupled to a Trimble GPS handset for automated data logging at one measurement per second. A distance of 2-4 inches above the ground surface was maintained throughout the survey. Evaluation of the GPS data files indicate that an average speed of approximately 0.5 ftjsec. was achieved during the FSS, although standard deviations and ranges do vary widely.

Planned screening levels were determined based upon the survey unit background count rate plus three standard deviations. The survey data were then color coded as follows: green= mean+/- 2STDEV; yellow= between mean+/- 2 and 3 STDDEV, and red=> mean+/- 3 STDDEV.

Areas coding yellow or red were investigated through visual inspection, field measurements, andjor sampling and gamma spec analysis. Samples resultmg from the evaluation of the gamma walkover survey data have been called "biased" samples, i.e. biased to areas of higher gamma readings, and identified with "-8" in the sample name. These samples are non-systematic and in addition to the thirteen systematic samples identified by "-S" in the sample name .

Static Measurements - Static measurements were performed by placing the columnated 2 x 2 on contact with the soil at the location to be sampled. Counts were performed for 1 minute and recorded prior to sample collection.

Sampling and Analysis- Soil samples were collected using a stainless steel hand trowel. The onsite laboratory was set up and maintained to count soil samples in the 1.65 L Marinelli geometry. All samples were collected and prepared in order to provide approximately 1000 grams of uniform granular/soil matrix. During the removal action phase of the project it was determined that the target contamination was present in the fines Of the mixed rock, gravel, sand, and soil matrices. Using a· No. 10 sieve, rock and gravel (coarse) were separated from the sand and soil (fines). Analysis of the respective fractions indicated that the 226Ra

contamination was not present in the coarse fractions and did indeed reside in the fines fractions. Thereafter, all analyses were sieved. All FSS samples were sieved through a No. 10 screen. Samples too wet to sieve were allowed to air dry until they would sieve with minimal force/disturbance. Three samples, associated with the additional removal action around the telephone pole were not sieved. These samples were a uniform soil matrix that was amenable to analysis as is.

In accordance with the FSSP, an onsite gamma spectroscopy system was employed to provide real time support to the removal action activities and final status survey analyses. The system consisted of a 3x3 Nal detector with a Multi-Channel Analyzer (MCA) connected to a laptop computer running the Canberra Genie 2000 software. The calibration certificate for this system is presented in Appendix C. Standard lead brick shielding was used to minimize background levels allowing for low level determinations of226Ra concentrations. Certified reference materials were. used for instrument initial calibration and for verification of continuing calibration performance, Appendix C. Background analyses were performed initially at set up and then periodically thereafter to assure background stability.

For feature surfaces data was collected to satisfy NRC Regulatory Guide 1.86 to include:

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1. 2. 3.

Surface Scans Static Measurements Smear Sample Collection



Surface Scans - The surface was scanned for alpha and beta contamination by moving the respective probe in straight paths covering 100% of the available feature surface area. The scan survey action level was a sustained instrument response above the background level. Areas providing a sustained instrument response above background would be marked and identified for subsequent static measurement and smear sample. Surfa~e scan data were not recorded.

Static Measurement- Static measurements were collected at areas of elevated surface scan readings or as determined by profes~ional judgment and/or visual observation. Static measurements were collected for 5 minutes for alpha determinations and for 1 minute for beta/gamma determinations with the instrument placed in scaler mode. The fixed-point (static) survey action levels were the respective total release limits in accordance with NRC Regulatory Guide 1.86 (Table, Section 2.2).

Smear Sample Collection- The amount of removable contamination per 100 cm2 of surface area was determined by wiping that area with a dry filter paper, applying moderate pressure, and analyzing the smears as appropriate. Smears were counted using a detector capable of meeting the release criteria for removable contaminati'on in accordance with NRC Regulatory Guide 1.86 (Table, Section 2.2) plus the average background specific to the material type being evaluated. Surface release data are presented in Appendix D.

4.6 Survey Results

The following sections present the results of the final status survey measurements and laboratory data followed by a summary of the surface release surveys. It is organized by media (land areas and surfaces). The land area discussion is further organized by method (survey, static measurements, and soil samples). The land areas discussion is in chronological order with the field event and includes both characterization and final status survey results. The text clearly states the type of sample being collected (e.g. Systematic, biased, walkover) and the phase ofthe project (characterization or final status survey).

4.6.1 Excavated Land Area

Gamma Walkover Surveys

Gamma walkover surveys were conducted during three different phases of the project The first phase was at the beginning of the project to establish background reference area values (and collect field instrument specific performance data). The second phase was to verify additional post-removal action conditions when initial results indicated that additional removal was required. The third phase was to establish/demonstrate final status conditions once removal actions were complete.

Evaluation of the GPS data files indicate that an average speed of approximately 0.5 ftjsec. was achieved during the performance of gamma walkover surveys, although standard deviations and ranges do vary widely.

Screening levels from the gamma walkover survey of the site were evaluated as described above. Fig~;~ res 2 through 4 present the gamma walkover survey data and are color coded as follows: green = mean+/- 2STDEV; yellow= between mean+/- 2 and 3 STDDEV, and red=> mean+/- 3 STDDEV. Areas coding yellow or red were investigated through visual inspection, field measurements, and/or sampling and gamma spec analysis. Evaluation of the gamma walkover data of the survey resulted in the collection of four additional biased soil samples discussed in Soil Sampling and Analysis below.

All gamma walkover data statistics were comparable and statistically valid. Means and medians were comparable across all data sets and correlated well between each data set. Standard deviations were reasonable and as expected. All walkover survey data were collected using a columnator, i.e. a

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lead shield around the sides of the Nal detector. Use of the columnator reduces background and inci.dental radiation while focusing the detector "view" toward the ground su'rface.

A kriown reference area located on Ascot Avenue east of 20th Street was identified for use. A sub-area of approximately 400 m2 (commensurate with the SU 1 area of 411 m2) was surveyed to represent background reference measurement data. Figure 2 presents walkover gamma survey results for the background reference area. The red areas were investigated and found to be areas of concrete footings/pads; therefore, the elevated readings are believed to be due to different materials. Summary statistics for the Reference Area gamma walkover data are presented"below in counts per minute (cpm).

• Min= 2221 • Max= 3248 • Mean= 2708 • Median= 2715 • Std Dev = 162

Figure 3 presents the 100% gamma walkover survey conducted in SU1 to demonstrate final status. Prior to performing the gamma walkover survey for SU1, it was known through field investigations that there were two small areas that would require additional removal action. These two areas are shown within the survey unit boundary in areas of red dots (greater than 3,194 cpm). Pieces of contaminated asphalt were identified at the base of the telephone pole and at the base of the surface waier line junction box. This additional removal action for asphalt pieces is discussed in Section 4.1. In order to maintain schedule the gamma walkover survey for the survey unit was conducted prior to the additional removal action. As expected, the areas immediately adjacent to the telephone pole and the storm water junction box indicated elevated readings, i.e. the red areas. Additionally, the areas colored yellow were investigated. Locations were identified within these yellow areas and sampled as bias sample locations (discussed below and shown in Table 6). The summary statistics for the SU compared well with those from the background data set. Means and medians are comparable. Although the range values vary, the industrial setting for SU1 contains materials of construction, e.g. asphalt, sand, gravel, that should not be expected to provide results completely consistent with the non-industrial background reference data. Additionally, the removal action in SU1 resulted in a surface of approximately one foot below grade on average creating regions of detection geometry that were different from that of the planer, undisturbed background reference area. Summary statistics for the SU 1 gamma walkover data are presented-below in cpm. -

I

~ Min= 1412 • Max= 3996 • Mean= 2718 • Median = 2691 ' • Std Dev = 288 I

Following the additional removal action, a gamma walkover survey was performed for the affected areas and is presented in Figure 4. The combination of pre- and post-additional removal action gamma walkover data or overlay of Figure 4 onto Figure 3 represents the final site gamma walkover conditions. Summary statistics for the additional removal action gamma walkover survey data are presented below in cpm .

• Min= 2187 • Max= 3577

• Mean= 2986 • Median = 3040 • Std Dev = 266

While the scan MDCs for the columna ted 2 x 2 Nal detectors are not sufficient to determine the presence or absence of 226Ra at or below the 2 pCi/g release criteria, analysis of samples collected from areas indicating elevated readings were either below or slightly above the 2 pCifg release level

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indicating that the columnated 2 x 2 was sufficient and useful as an indicator to guide additional sampling and removal action.

The gamma walkover data representing site conditions following removal actions indicates that the site is comparable to the background reference area. The Screening level (reference area average plus three standard deviations) was 3,194 cpm.

Area Minimum Maximum Mean Median Std Dev Screening Level

Background Reference Area I 2221 I 3248 I 2708 I 2715 I 162 I 3194

All data in counts per m1nute (cpm)

It had been acknowledged that the static and scan MDCs for 226Ra may be above the site release criteria of 2 pCi/g and that the gamma survey may be unable to measure 226Ra at release levels. Therefore, the gamma survey was only intended to provide screening level data. Follow-up soil sampling was conducted to provide definitive data to characterize the 226 Ra concentrations and is presented later.

While there are some areas of the SU that remain above the Screening Level (established from the non industrial background reference area), samples analyzed over the full range of gamma walkover values indicate that the associated soil concentrations are less than the site release criteria of 2 pCi/g 226Ra. Gamma walkover survey measurements in excess of the Screening Level (established from the non industrial background reference area) are believed to be due to the presence of non-soil industrial materials and differing detector geometries.

Static Measurements

Static measurements were collected at each sampling location prior to soil sample collection. Additionally, static measurements were collected in the background reference area for comparison purposes. Table 5 presents both the static measurements collected in the background reference area using two instruments (primary and backup) and in SUl(primary instrument only). The scatter plot shown after the table indicates that there is good agreement for a large part of the SU with the reference area measurements. The SU direct measurements collected toward the end of the project are believed to be biased high as most of these measurements were being taken associated with samples collected around or near the telephone pole and storm water concrete junction box both of whi.ch should be expected to be elevated due to different matrices, e.g. concrete, and geometries, i.e. excavations around these areas were deeper and provided a greater than two pi geometry.

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TABLE 5. STATIC COUNT MEASUREMENTS, ON CONTACT, 1 MINUTE COUNTS

Dudley SU1 Contact Static Measurements (cpm) Background Reference Area Static Measurements (cpm) SU1 Location Point ID Instrument 2• Point ID Instrument 1" Instrument 2" SU1-101 1 2,735 1 2564 2568 SU1-102 2 2,552 2 2652 2527 SU1-103 3 2,493 3 2480 2626 SU1-104 4 2,529 4 2589 2502 SU1-105 5 3,001 5 2513 2517 SU1-106 6 2,594 6 2540 2559 SU1-107 8 2,954 7 2553 2526 SU1-108 9 2,968 8 2554 2513 SU1-109 11 2,952 9 2425 2361 SU1-110 13 2,955 10 2520 2583 SU1-111 15 2,630 11 2651 2489 SU1-112 16 2,717 12 2553 2664 5U1-113 17 3,018 13 2654 2545 SU1-114-P 19 2,333 14 2591 2379 SU1-115-P 20 2,438 15 2377 2310 SU1-116-B 22 2,818 Instrument 1" Instrument 2• SU1-118-B 25 3,264 Min 2377 Min 2310 SU1-119-B 26 2,809 Max 2654 Max 2664 MDB-04G-C 27 3,783 Mean 2548 Mean 2511 MDB-041-C 28 3,076 Median 2553 Median 2526 MDB-042-c 29 3,575 Std Dev 79 Std Dev 96

DudleySU1 Combined Instruments 1" & 2• Min 2333 Min 2310 Max 3783 Max 2664 Mean 2866 Mean 2530 Median 2818 Median 2543 Std Dev 361 Std Dev 89

a Instrument description and identification presented in Table 3

Soil Sampling and Analysis

There were three types of soil samples collected during this FSS;

Systematic - Thirteen systematic samples were collected as specified in the FSS design. These sample locations were selected using a randomly placed triangular sampling grid. The grid was established in accordance with the survey design using the area of the survey unit, the number of samples required and the length of each grid segment as discussed in Section 3.1.7. These samples are identified by "-S" in the sample name.

Bias (non-systematic)- Biased samples were collected following an evaluation of the gamma walkover survey data as described in Section 4.5. These samples are identified by" -B" in the sample name. As a result of survey evaluation, four additional biased soil samples; SU1-116-B, SU1-117 -B, SUl-118-B, and SU1-119-B and are discussed below .

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Professional Judgment (non-systematic)- Professional judgment samples were collected as determined prudent from the technical staffs experience, observed anomalies, or other conditions that warrant additional sample data. These samples are identified by "-P" in the sample name. Two additional professional judgment soil samples; SUl-114-P and SUl-115-P were collected and are discussed below.

Characterization (non-systematic)- Characterizations samples were collected to characterize the site prior to, during, and/or post removal action activities. These samples may or may not represent final status conditions. These samples are named as "MDB-XXX-C'' where XXX is a sequential numerical index. Five additional characterization samples collected post minor additional removal action have been used to support the final site conditions and are discussed below.

NOTE: No "less than" values or Minimum Detectable Activity (MDA) results were used in the evaluation of site data. For all samples, 214 Bi (609 keV) was qualitatively and quantitatively reported. No negative numbers were reported or used for the evaluation and analysis of site data. All data presented below, unless otherwise noted, represent the results from the 214 Bi 609 keY energy line resulting from one hour sample count times performed in the onsite laboratory. The analytical system is discussed further in Section 5.1 of this FSSR Appendix K presents a data summary for all subject analytes for all samples presented in this FSSR

Table 6 below presents the sample identification, static measurement and analytical data for the final status systematic samples. Figure 5 presents a graphic display of the final status systematic samples collected.

TABLE 6. SYSTEMATIC SOIL SAMPLE RESULTS FOR FINAL STATUS SURVEY

STATIC MEASUREMENT ZZ5RA (609 keY) UNCERTAINTY

SAMPLEID COMMENTS (CPM) (PO/G) +/- 2I (PO/G) MDC(PO/G) NO. 10 SIEVED

FINES, FSS LOCATION SU1-

0.74 0.12 0.47 SU1-101 101 2,735

NO. 10 SIEVED FINES, FSS

LOCATION SU1-SU1-102 102 2,552 0.70 0.09 0.35


LOCATION SU1-SU1-103 103 2,493 0.59 0.10 0.40


LOCATION SU1-SU1-104 104 2,529 0.64 0.10 0.40


LOCATION SU1-SU1-105 105 3,001 0.82 0.11 0.40


LOCATION SU1-SU1-106 106 2,594 1.30 0.12 0.38


LOCATION SU1-SU1-107 107 2,954 0.89 0.12 0.41

SU1-108 NO. 10 SIEVED 2,968 1.38 0.13 0.41

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STATIC MEASUREMENT ~(609keV)



UNCERTAINTY SAMPLEID COMMENTS (CPM) (PO/G) +/-U(PO/G) MDC(PO/G)

SAMPLE ID

SU1-114-P

SU1-115-P

SU1-116-B

SU1-117-B1

SU1-118-B

SU1-119-B


108 NO. 10 SIEVED


SU1-109 109 2,952 0.93 0.10 0.35 NO. 10 SIEVED


SU1-110 110 2,955 0.73 0.11 0.43 NO. 10 SIEVED


SU1-111 111 2,630 0.63 0.10 0.37 NO. 10 SIEVED


SU1-112 112 2,717 0.99 0.13 0.42 NO. 10 SIEVED


SU1-113 113 3,018 0.67 0.10 0.38

In addition to the systematic samples, static measurements and soil samples were collected at four biased locations where gamma walkover surveys indicated elevated readings and at two locations based upon professional judgment on the western edge of the excavation that was not sufficiently covered by the systematic grid. Sample locations selected as bias are indicated with "-B" in the sample name and those selected based upon professional judgment are indicated by a "-P" in the sample name. Table 7 below presents the sample identification, static measurement and analytical data for the non-systematic (professional and biased) samples. Figure 6 presents a graphic display of the professional and biased samples collected.

TABLE 7. NON-SYSTEMATIC SOIL SAMPLE RESULTS FOR FINAL STATUS SURVEY

STATIC MEASUREMENT ~(609 UNCERTAINTY MDC

COMMENTS (CPM) keV)(PO/G) +/- 21 (PO/G) (PO/G)

NO. 10 SIEVED FINES, PROF JUDG, BOUNDING WEST SIDE OF SAND TRENCH 2,333 0.63 0.11 0.46

NO. 10 SIEVED FINES, PROF JUDG, BOUNDING WEST SIDE OF SAND TRENCH 2,438 0.99 0.15 0.56

NO. 10 SIEVED FINES, WARNING LEVEL FROM GAMMA WALKOVER 2,818 0.77 0.11 0.42

NO. 10 SIEVED FINES, WARNING LEVEL FROM GAMMA WALKOVER 3,489 2.21° 0.18 0.49



• locat1on was subsequently remed1ated andre-sampled as MDB-04!H: (below)

As discussed previously, concurrent with the collection of systematic and non-systematic final status samples, additional removal action was performed to remove pieces of contaminated asphalt present at the base of the telephone pole and at the base of the storm water junction box. Visual inspection

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and field instruments were used to confirm the removal of all remaining asphalt as practicable. The samples collected post-additional removal action where named as characterization samples indicated by a "-C" following the sample id and those presented do represent final site conditions.

One of the four additional biased sample locations (SU1-117-B) was within the footprint of the additional removal action and is therefore no longer indicative of final site conditions. Sample MDB-040-C was collected in this same location and therefore replaces the data from sample SU1-117-B. All final, current condition sample results were less than the 2.0 pCif g release criteria with the exception ofSU1-119-B.

Table 8 below presents the post additional removal action samples collected. Figure 7 presents those samples collected post-additional removal action.

TABLE 8. POST ADDITIONAL REMOVAL ACTION SAMPLES

STATIC

MEASUREMENT n'RA(609 UNCERTAINTY

SAMPLEID COMMENTS (CPM) keV) (PCI/G) +/- 2I (PO/G) MDC(PO/G)

NO. 10 SIEVED FINES, NORTH EAST CORNER MDB-040-C OF STORM WATER JUNCTION BOX 3,783 1.00 0.09 0.28

NO. 10 SIEVED FINES, STORM WATER UTIUTY MDB-041-C BOX EXCAVATION 3,076 0.70 0.09 0.31

NO. 10 SIEVED FINES, NORTH AST CORNER OF MDB-042-C WPOTHOLE 3,575 1.14 0.11 0.35

UNSIEVED, UNIFORM SOIL, BOTIOM OF MDB-043-C TELEPHONE POLE RA - 1.18 0.12 0.38

UNSIEVED, UNIFORM SOIL, SIDEWALLS OF MDB-044-C TELEPHONE POLE RA - 0.86 0.11 0.36

Note: Static measurements were not collected for post-additional removal action samples MDB-043-C and MDB-044-C due the fact that the excavation around the base of the telephone pole was approximately two feet in diameter and three feet deep creating non-comparable detector geometry. Static measurements would have been biased extremely high due to geometry considerations and not comparable or meaningful.

Table 9 below presents the systematic, non-systematic, and post removal sample data that represents the sites final condition. Figure 8 presents the samples and data representing the final condition of the SU, i.e. excavation area. Figure 9 presents a posting plot of the final condition site data.

TABLE 9. SYSTEMATIC, NON-SYSTEMATIC AND POST REMOVAL ACTION SAMPLES

STATIC SAMPLE MEASUREMENT 226RA(609 UNCERTAINTY MDC

ID COMMENTS (CPM) keV) (PCI/G) +/- 2I (PCI/G) (PCI/G)

SUl-101 NO. 10 SIEVED FINES, FSS LOCATION SU1-101 2,735 0.74 0.12 0.47

SU1-102 NO. 10 SIEVED FINES, FSS LOCATION SU1-102 2,552 0.70 0.09 0.35


SU1-104 NO. 10 SIEVED FINES, FSS LOCATION SU1·104 2,529 0.64 0.10 0.40



SU1-107 NO. 10 SIEVED FIN ES, F5S LOCATION SU1-107 2,954 0.89 0.12 0.41

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STATIC



SAMPLE MEASUREMENT 22&RA(609 UNCERTAINTY MDC ID COMMENTS (CPM) keV) (PCI/G) +/- 2I (PCI/G) (PCI/G)







NO. 10 SIEVED FINES, PROF JUDG, BOUNDING SU1-114-P WEST SIDE OF SAND TRENCH 2,333 0.63 0.11 0.46

NO. 10 SIEVED FINES, PROF JUDG, BOUNDING SU1-115-P WEST SIDE OF SAND TRENCH 2,438 0.99 0.15 0.56

NO. 10 SIEVED FINES, WARNING LEVEL FROM SU1-116-B GAMMA WALKOVER 2,818 0.77 0.11 0.42



NO. 10 SIEVED FINES, NORTH EAST CORNER OF MDB-Q4Q-C STORM WATER JUNCTION BOX 3,783 1.00 0.09 0.28

NO. 10 SIEVED FINES, STORM WATER UTILITY MDB-Q41-C BOX EXCAVATION 3,076 0.70 0.09 0.31

N0.10SIEVED FINES, NORTH ASTCORNER OF MDB-Q42-C WPOTHOLE 3,575 1.14 0.11 0.35

UNSIEVED, UNIFORM SOIL, BOTIOM OF MDB-Q43-C TELEPHONE POLE RA - 1.18 0.12 0.38

UNSIEVED, UNIFORM SOIL, SIDEWALLS OF MDB-Q44-C TELEPHONE POLE RA - 0.86 0.11 0.36

Note: Static measurements were not collected for post-additional removal action samples MDB-043-C and MDB-044-C due the fact that the excavation around the base of the telephone pole was approximately two feet in diameter and three feet deep creating a non-comparable detector geometry. Static measurements would have been biased extremely high due to geometry considerations and not comparable or meaningful.

Analytical data reports for the systematic, non-systematic and post-additional removal action samples are presented in Appendix F.

4.6.2 Surface Release

There were four features that required surface release surveys in accordance with NRC Regulatory Guide 1.86: the base of a telephone pole, a concrete utility box servicing the telephone pole, a concrete utility box associated with the storm water management system, and an iron manhole that is believed to service the underground electrical service.

In accordance with the FSSP, these site features were surveyed and released in accordance with NRC Regulatory Guide 1.86. Available surfaces were scanned 100% with alpha and beta direct reading instrumentation. Direct measurements and smear samples were collected at locations selected upon professional judgment and/or biased to represent worst case conditions. No elevated measurements were noted during the 100% scan of these items. Direct measurements and smear sample results were all below subject release criteria. The release surveys are presented in Appendix D. Calibration certificates for all field measurement instrumentation are presented in Appendix C .

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5.0 DATA EVALlJATION

5.1 Data Quality Assessment

Field Survey Instrumentation



Field instrumentation used for the survey and release of feature surfaces were monitored daily for operation and performance. All field instruments functioned properly and maintained control during the final status survey operations. Daily background and source checks are presented in Appendix B. Calibration certificates for all field measurement instrumentation and Standard Reference Materials (SRM) are presented in Appendix C.

Onsite Laboratory Operations

Within a closed system, all of the 226Ra daughters would be in equilibrium (equal activity concentrations) with their parent radionuclide, i.e. 226Ra. However, during sampling activities 222Rn and its daughters may be partially depleted due to the emanation of222 Rn which is a noble gas at standard temperature and pressure. The loss of 222 Rn creates a less than equilibrated 2148i concentration. The fraction emanated varies with the containing matrix and atmospheric conditions. The typical emanation is in the range of 20 to 30 percent, i.e. the analysis:of 2148i would yield a result indicating 20 to 30 percent lower 226Ra concentration. Once a sample is sealed, daughter in-growth follows the 3.8 day half-life, i.e. after 3.8 days, half of the daughters are restored; after 7.6 days% of the daughters have grown in; about 97% in 20 days. After 20 days, 2t48i can be considered to be in equilibrium with parent 226Ra. At equilibrium, the higher abundance 2t48i provides a quantitative result for wiRa having less uncertainty than quantification from the lower abundance 186 keV gamma ray directly from 226Ra. However, measurement of the low abundance 186 keV gamma ray from 226Ra is not affected by radon emanation and is available for analysis immediately following sampling. Therefore, in consideration of project schedules the 186 keV gamma ray from 226Ra was intended to be the primary consideration for onsite analysis. However, due to site conditions, sample matrices, interference from nonCDC radionuclides (primarily low levels of23SU), and observed variability in quantitation from the 186 keV 226Ra energy line, it was determined that the 609 keV energy from the 2t48i daughter would provide a more stable indicator of 226Ra concentrations. While the 186 keV energy line from 226Ra was assessed for all

, I

samples analyzed, the data reported and utilized in the subject final status determination results from the quantitative reporting of the 609 keV energy line from the 214Bi daughter. These evaluations were further substantiat~d by the use of field splits, i.e. samples sent to an offsite laboratory for analysis, and by on-site serial analysis, i.e. reanalysis, of collected samples in order to assess the rate of2148i in growth. Both offsite analysis of S

1plit or same sample aliquots and the serial analyses of samples onsite support the use of the 609

keV data fromthe2t48i daughter as reported.

The onsite g:amma spectroscopy system consisted of a 3x3 Nal detector connected to an Osprey MultiChannel Analyzer (MCA) .. The system was well shielded using standard lead bricks to form walls on four sides of the detector extending up to the top of the sample container. The shielding did not provide for a tope cover. The counting system was set up and maintained in an environmentally stable area without temperature or power supply variances/interruptions. All sample count times were for one hour (live time). For all samples, detector dead time was negligible. This system was connected to a laptop computer running the Canberra Genie 2000 software. The system arrived having been tested and calibrated. Standard reference m~terial (SRM)'was acquired and placed into the 1.65 L Marinelli geometry. SRMs were at 5.12 and 50.2 pCi/g 2?6Ra. Certificates for the SRM are presented in Appendix C. The system was calibrated to the 5.12 pCijg 226Ra SRM. Upon arrival on site, the system was set up, background was established and verified, and .the system was again recalibrated to the 5.12 pCi/g 226Ra SRM. The 50.2 pCijg 226Ra SRM counted periodically) however, since this SRM was well above the range of interest it was not routinely analyzed. There were two days, 10/18 and 19/2011 during which a software error was not integrating the regions of interest properly. However, inspection of the spectra concluded that the total counts were correct and in control confirming a software error and not a detector hardware error. There were no final status or postadditional removal action samples analyzed during this period. Also, none of the analyses performed during

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this period were utilized or any decision making purposes and all subject samples were reanalyzed after the problem had been resolved. Table 10 presents daily SRM source check performance for the onsite laboratory.

TABLE 10. DAILY SRM (5.12 PCI/G) SOURCE OiECK PERFORMANCE

5.12 pCl/g ... Ra Standard

Date Time Bi-214 %Recovery Pb-214 %Recovery 226fta %Recovery COMMENTS 9/30/2011 180515 5.41 105.66% 4.87 95.12% 3.87 75.59% OK 10/1/2011 093816 5.34 104.30% 4.97 97.07% 5.09 99.41% OK 10/1/2011 110031 5.03 98.24% 4.87 95.12% 5.03 98.24% OK 10/2/2011 002243 5.26 102.73% 4.72 92.19% 4.15 81.05% OK 10/2/2011 132956 5.29 103.32% 5.01 97.85% 4.73 92.38% OK 10/2/2011 192618 4.83 94.34% 4.88 95.31% 6.21 121.29% OK 10/4/2011 001310 5.21 101.76% 4.88 95.31% 4.40 85.94% OK

10/10/2011 133101 5.44 106.25% 5.18 101.17% 5.10 99.61% OK 10/12/2011 103737 5.40 105.47% 4.99 97.46% 4.90 95.70% OK 10/16/2011 215750 6.23 121.61% 4.97 97.03% 4.52 88.25% OK 10/17/2011 072723 4.34 84.73% 5.06 98.82% 5.92 115.53% OK 10/17/2011 181819 4.22 82.46% 5.15 100.56% 7.10 138.66% OK

Fall. Software error. Not integrating peak properly. Total

10/18/2011 153948 0.18 3.52% 5.04 98.35% NO Not Calculated Area counts 0 K. Fail . Software error. Not Integrating peak properly. Total

10/18/2011 202615 0.20 3.88% 5.08 99.21% NO Not Calculated Area counts 0 K. Fail . Software error. Not integrating peak properly. Total

10/18/2011 204623 NO Not Calculated 5.25 102.54% NO Not Calculated Area counts 0 K. Fail. Software error. Not integrating peak properly. Total

10/19/2011 020950 0.15 2.85% 5.01 97.89% NO Not Calculated Area counts 0 K. 10/20/2011 164431 4.98 97.19% 4.87 95.04% 5.39 105.26% OK 10/20/2011 212613 4.69 91.67% 4.85 94.81% 6.87 134.20% OK 10/22/2011 002852 5.25 102.58% 5.13 100.21% 4.70 91.85% OK 10/22/2011 101707 5.21 101.73% 5.00 97.75% 6.29 122.91% OK 10/22/2011 231958 5.42 105.93% 4.88 95.26% 6.20 121.07% OK 10/23/2011 134526 4.54 88.63% 5.02 97.95% 8.56 167.21% OK 10/23/2011 231732 5.04 98.36% 5.07 99.07% 5.74 112.05% OK 10/24/2011 205151 4.62 90.19% 5.17 101.06% 5.53 107.97% OK 10/24/2011 220457 4.65 90.76% 5.14 100.39% 7.25 141.6d% OK 10/25/2011 003535 5.03 98.26% 4.95 96.78% 5.30 103.59% OK

Bi-214 %Recovery Pb-214 %Recovery 226fta %Recovery Does not include data generated during troubleshooting

MIN 4.22 82.46% 4.72 92.19% 3.87 75.59% 10/18,19/2011 Does not include data generated during troubleshooting

MAX 6.23 121.61% 5.18 101.17% 8.56 167.21% 10/18,19/2011 Does not include data generated during troubleshooting

MEAN 5.06 98.92% 4.98 97.33% 5.58 109.06% 10/18,19/2011 Does not include data generated during troubleshooting

MEDIAN 5.12 100.05% 4.98 97.27% 5.35 104.42% 10/18,19/2011

. Does not include data generated during troubleshooting

STDDEV 0.45 8.72% 0.12 2.43% 1.14 22.31% 10/18,19/2011

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Off Site Laboratoty Comparisons



Throughout the performance of the project, eleven split samples from various phases of work and materials were sent to offsite laboratories to confirm the onsite gamma spec system performance and analyses. However, only six of these were handled, i.e. collected and prepped, as final status samples and are representative of the final status condition of the site. Table 11 presents the onsite and offsite results for these final status field split samples.

TABLE 11. ONSITE/OFFSITE LABORATORY EVALUATION

ON-SrrELAB OFF-SITE LAB WIN GROWTH (609 KEV)

SAMPLEID IsoTOPE PO/G +I- (2I) MDC PCJ/G +I- (2I) MDC

SU1-101 (GEL) Bi214 (609 keV) 0.74 0.12 0.47 1.06 0.16 0.09

SU1-103 (Eberline) Bi214 (609 keV) 0.59 0.10 0.40 0.86 0.11 0.08

SU1·106 (GEL) Bi214 (609 keV) 1.30 0.12 0.38 2.52 0.35 0.14

SU1-109 (Eberline) Bi214 {609 keV) 0.93 0.10 0.35 1.48 0.17 0.11

SU1-113 (GEL) Bi214 (609 keV) 0.67 0.10 0.38 0.67 0.15 0.10

MDB-115-P (Eberline) Bi214 (609 keV) 0.99 0.15 0.56 1.63 0.21 0.15

A scatter plot of the onsite vs. offsite data is present below.

Scatter Plot Onsite Ra226(609 keV} vs. Offsite Ra226 (609 keV}

..: $ .c 110 :1

"' 0 :!; N

3.0

2.5

iii c 2.0 0 -a Cll

"' "' 11::1 > 1.5 "' Cll

.!~: 1;o ::. ID 1.0 c Cll u c 8 1D 0.5 N N

"' a: .a ..!! 0.0 Cll .t: "' c 0

n ""'"~. ,... .. ..,, ' , ..... ~~ -n 7,:0CI----_.

........ 6........::;/( .....

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Offstie Lab Ra226 Concentrations Based On Bi214 Daughter, 609 keV

+ Series1

--Linear {Series 1)

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Summary Statistics for the Offsite/Onsite Comparison Ratios

1.93 Max

1.07 Min

1.52 Median

1.52 Mean

0.28 Std Dev

0.86 Range

3.04 R/Std Dev



GEL Laboratories located in Charleston, South Carolina are the laboratory of record for the analysis of project field split samples. GEL is well recognized in the area of environmental radiochemistry and holds certification1s, accreditation, and/or is audited against numerous national and global quality standards to include; National Environmental Laboratory Accreditation Conference (NELAC), American Society of Mechanical Engineers (ASME)/ Nuclear Quality Assurance, Levell (NQA-l),lnternational Organization for Standardization (ISO)/ International Electrotechnical Commission (IEC) Guide 17025, Multi-Agency Radiological Laboratory Analytical Protocols (MARLAP), and Department of Energy Consolidated Audit Program (DOECAP). GEL successfully participates in nationwide audit programs and inter-comparison studies to in'clude those managed by EPA, NRC, and the United States Department of Energy (DOE).

Informational project field split samples were also sent to Eberline Analytical Services. Eberline is also well recognized in the area of environmental radiochemistry and holds certifications, accreditation, and/or is audited against numerous national and global quality standards to include; National Environmental Laboratory Accreditation" Program (NELAP) and DOECAP. GEL successfully participates in nationwide audit programs and inter-comparison studies to include those managed by EPA and DOE.

From the data above, it can be seen that the onsite data correlate well with the offsite laboratory data, i.e. coefficient of cor~elation is equal to 0.9769. The summary statistics are acceptable. Specifically, the Median and Mean are comparable, the standard deviation is acceptable, and the R/Standard Deviation ratio indicates that normally incident to' a valid data set. However, an evaluation of the slope indicates that there may be a low bias in the onsite data relative to the offsite data. Differences between onsite and analytical results arise for a variety' of reasons and conditions. Systematic differences are primarily due to analytical instrumentation and environmental conditions. For the offsite analyses used in the comparison the samples were analyz:ed by a High Purity Germanium (HPGe) detection system. These systems have different sensitivities! over the energy range of concern as well as have a higher spectral resolution. They are superior for more cm:nplex mixtures of isotopes and are not as affected by environmental conditions as are the Nal detection sy~tems used for the onsite analysis. However, the analytical spectra for the subject project samples were relatively simple, i.e. non-complex, with respect to targe_t and non-target analytes and potential

. interferences. Additionally, environmental factors such as altitude, laboratory facility construction, and . geographical location can create differences in the performance of analytical systems. Another consideration when comparing results from different analytical laboratories is the extent to which the sample matrix and its conditions compare with the standard reference materials used for calibration and standardization. Analytical results between facilities, and within a facility, can vary to the extent that the sample matrices differ from the standard reference materials. Standard reference materials are manufactured under controlled c~nditions and are generally of pure, dried, homogenized materials. The effects of differing sample matrices are more random in nature and hard to predict with sample specific studies done to isolate and quantify the bias and/or uncertainty and do exist for all analytical laboratories. However, it is these differences and potential variabilities, while providing comparable results, which provide an independent analysis that lends credence to the on site generated data.

Of the remaining primary causes for differences between the onsite and offsite data, there are three that have the potential to influence comparability the most and are associated with sample preparation, i.e. drying, ingrowth considerations, and sample aliquot size .

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0 Drying



• Onsite Analysis: Samples were determined "dry" based upon visual inspection, handling, and professional judgment. Samples were not dried "analytically". The samples were determined dry if they appeared dry and behaved as dry, i.e. if when handled the material remained in a granular state and could be easily sieved. Samples that were more clay-like in nature were allowed to be air dried until they could be crushed and sieved.

• Offsite Analysis: Samples were analytically dried, g~ound, and containerized in accordance with standard gamma· spectroscopy sample preparations procedures designed to homogenize the sample and place into sealed containers that are set aside for a twenty-one day in-growth period (effects of in growth described below).

• Effects: Available m01sture content data from the offsite analyses indicated an average of approximately ten percent moisture for the subject sample set. Since the concentration in pCifg is weight based, and drying lowers the mass of the absolute weight of sample counted, it can be assumed that the offsite laboratory results should be an approximately similar ten percent biased high over the onsite laboratory result due to the more complete drying performed by the offsite laboratory.

o In-growth Period

• Onsite Analysis: Due to the aggressive field schedule, samples were analyzed as soon as possible after containerization, i.e. placed into the Marinelli beaker, and therefore not allowed time for appreciable in-growth of the 214Bi at the 609 keY energy line . Typically, some amount of 222Ra (gas) is liberated during sample collection and handling and in-gro:wth period allows the 226Ra to re-equilibrate with it daughter isotopes, e.g. Z148i.

• Offsite Analysis: After sealed containerization, samples were allowed to sit for twenty-one days to allow for in-growth of the Z148i.

• Effect: The effects of in-growth are hard to predict but can be considered one of the potentially larger effects between the onsite and offsite analyses. Since the effect of in-growth is difficult to isolate, is not readily quantifiable without additional study, and is additionally affected by aliquot size (discussed below), the "as reported" data were evaluated under two additional scenarios discussed later in this section.

o Sample Aliquot Size

• Onsite Analysis: The entire sample collected was prepared and placed into the Marinelli beaker for subsequent analysis. Due to the variety of matrices analyzed, e.g. sand, soil, and clay, the analyzed mass of samples ranged from approximately 650g to 1400g.

• Offsite analysis: In addition to drying the sample, the offsite lab preparation involved sub-sampling, i.e. removing an aliquot (approximately) lOOg from total mass of sample delivered. While the sub-sampling procedure is designed to yield a sub-sample that is representative of the entire sample, contaminant heterogeneity in the sample matrix can yield appreciably different results.

• Effects: While sub-sampling and the uncertainty regarding the distribution of the contaminant through the sample matrix can lead to large difference between two laboratory results, it is difficult to assign analytical differences to aliquot issues without additional study. Since the effect of aliquot is difficult to isolate and is not

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readily quantifiable without a more thorough study the "as reported" data were evaluated under two additional scenarios discussed later in this section.

In order to evaluate the impact on resulting decisions, the "as reported" data were modified in two ways, i.e. scenarios;

• Scenario 1) the onsite data were modified according to the functional relationship representing the resulting "line" between the onsite and offsite data (y = 0.3957X + 0.3211, R = 0.9769); and

• Scenario 2) the "as reported" data were multiplied by the Mean Offsite/Onsite result ratio.

While the a2tual numbers do vary between the scenarios, the resulting decisions with respect to statistical tests and resulting ciose remain unchanged. For each of the sections below, the "as reported" results are used as the primary data. The results of assessments for each of the additional scenarios considered above are also reported for informational/comparison purposes.

Wilcoxon Rank Sum

The mean ofthe systematic samples is 0.85 pCifg. The mean of all final site condition samples is 0.87 pCijg. Both values are less than the DCGL of 1.2 pCifg. Additionally, for the "as reported" data, the difference between the highest SU measurement and the lowest reference area measurement (1.38- 0.40 = 0.98 pCi/g) is less than the DCGLw (1.2 pCi/g). Therefore, performance of the WRS Test documentation would not normally be: required (EPA 2000). However, as stated above, in order to resolve concerns raised by an apparent low bias in the onsite vs. the offsite laboratory data, the as reported data, as well as the modified data from Scenarios 1 and 2, will be evaluated in order to assess the impact of a laboratory bias and to provide an additionally conservative site evaluation. For Scenarios 1 and 2 the difference between the highest SU measurement and the lowest reference area measurement is greater than the DCGLw (1.2 pCi/g), i.e. 2:28 and.1.70 pCijg respectively. Therefore, the WRS Test has been performed for the as reported data, Scenario 1, and Scenario 2. The WRS test (rather than the sign test) is used for final status survey samples when contalpinants are present in background. The WRS process is accomplished by calculating the · following: ·

I

• the relative shift; • determining the probability that a random measurement from the survey unit exceeds the

random measurement from the background reference area by more than the DCGL when the survey unit medium is equal to the lower bound of the grey region;

• determining decision error percentiles and the associated number of data points needed; and • evaluating results.

The 226Ra soil background studies have already been discussed with the resultant cleanup criteria of 2 pCi/ g inclusive of background.

For WRS test performanc.e, background reference area values will be randomly selected from the 226Ra values presented in the Revised Reference Area Final Status Survey Report (Cabrera Services 2004 ). Reference area values will be selected from the combined, undisturbed data set for 226Ra. The following presents the WRS test evaluation utilizing the on site analyses with 226Ra concentrations determined from the 609 keY energy line from the 2148i daughter.

Dudley Blvd - Wilcoxon Rank Sum Test

The following is a step by step evaluation of the analytical data in accordance with MARSSlM. The first sentence or paragraph presented, italicized, is a reiteration of the.protocol followed by a summary of the site specific information .

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Obtain the adjusted reference area measurements, Zi, by adding the DCGLw to each reference area measurement, Xi. Zi =Xi + 1.2.

As recommended in the site background report and confirmed by pre-project communications, reference background values (Xi) were randomly selected from the reference area background values for 226Ra.

XI (Ref Meas)

0.40 1.60

0.49 1.69

0.51 1.70

0.52 1.72 1.93 Max

0.54 1.73 1.60 Min

0.54 1.74 1.74 Median

0.54 1.74 1.75 Mean

0.57 1.76 0.07 Std Dev

0.57 1.77 0.33 Range

0.57 1.77 4.46 R/std dev

0.58 1.77

0.60 1.79

0.73 1.93

For the additional evaluations, i.e. Scenarios 1 and 2 described above, the background reference area values, i.e. Xi, and therefore Zi, do not change.

Them adjusted reference sample measurements from final status survey, Zi, from the reference and the n sample measurements, Yi, from the survey unit are poled and ranked in order of the increasing size from 1 toN, where N = m + n.

SampleiD

SU1-101

SU1-102

SU1-103

SU1-104

SU1-10S

SU1-106

SU1-107

SU1-108

SU1-109

SU1-110

SU1-111

SU1-112

SU1-113

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1.38

0.59

0.73

0.84

0.25

0.79

3.13

Max

Min

Median

Mean

Std Dev

Range

R/Std Dev



Summary statistics for the additional scenarios considered are as follows:

Scenario 1 ("as reported data modified by offsite vs. onsite line function (y = 0.3957X + 0.3211)):

2.6849 Max

0.6884 Min

1.0472 Median

1.3296 Mean

0.6363 Std Dev

1.9965 Range

3.1377 R/Std Dev

Scenario 2 ("as reported" data modified by offsitejonsite ratio mean (x1.52)):

2.1029 Max

0.9021 Min

1.1179 Median

1.2878 Mean

0.3827 Std Dev

1.2008 Range

3.1377 R/Std Dev

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3. If several measurement are tied (i.e. have the same value), they are all assigned the average rank of that group of tied measurements.

Complete Doto Set Ranked Data Set

Rank

26 26

For Scenarios 1 and 2 the individual values ranked against the background reference data are not provided. However, the WRS Test results are presented in item 5 below.

4. If there are t "less than"values, they are all given the average of the ranks from 1 tot. Therefore, they are all assigned the rank t(t+1}/(2 t}, which is the average of the first t integers. If there is more than one detection limit, all observations below the largest detection limit should be treated as "less than" values.

No less than values or MDCs were used in this FSSR.

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5. Sum the ranks of the adjusted measurements from the reference area, Wr. Note that since the sum of the first N integers in N(N+ 1}/2, on can equivalently sum the ranks of the measurements from the survey unit, Ws, and compute Wr = N(N+l)/2- Ws.

Ws (Summed Ranks ofSU Measurements)

Wr (Summed Ranks of Ref Area+ DCGL Measurements)

91

260




Scenario 2 ("as reported data modified by offsitejonsite ratio mean (x1.52)):



118

233

128

223

6. Compare Wr with the critical value given in Table 1.4 for the appropriate values of n, m, and a. If Wr is greater than the tabulated value, reject the hypotheses that the survey unit exceeds the release criterion.

Critical Value from MARSSIM Table 1.4 for n = 13, m = 13, a= 0.05, p = 0.05 is 208. Wr 260 and is greater than 208 and therefore we can reject the hypothesis that the survey unit exceeds the release criterion (DCGL of 1.2 pCi/g).

Likewise, for Scenarios 1 (Wr = 233) and Scenario 2 (Wr = 223), we can also reject the hypothesis that the survey unit exceeds the release criterion (DCGL of 1.2 pCifg).

A second independent WRS test was required in accordance with the request of the California Department of Public'Health. This second WRS includes the background reference area data and assumes a DCGL of zero. The results of the WRS Test assuming a DCGL of zero are presented below:


Wr (Summed Ranks of Red Area + DCGL Measurements)

253

98



Wr (Summed Ranks of Ref Area + DCGL Measurements)

Scenario 2 ("as reported data modified by offsitejonsite ratio mean (x1.52)):



259

92

252

99

age

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Final Status Survey Report Dudley Blvd Radiological Removal Act~on


Again, the Critical Value from MARSSIM Table 1.4 for n = 13, m = 13, a= 0.05, ~ = 0.05 is 208. For a DCGL of zero, Wr = 98 and is less than 208 and therefore the hypothesis that the survey unit exceeds the release criterion (DCGL of 0.0 pCi/g) cannot be rejected.

Likewise, for Scenarios 1 (Wr = 92) and Scenario 2 (Wr = 99), we cannot reject the hypothesis that the survey unit exceeds the release criterion when the DCGL is set to zero.

5.2 Dose Assessment

Using RESRAD Version 6.5 and restrictive exposure scenario settings the future dose in excess of background was determined to be 0.30 mRemjyear at year zero. Dose was assessed at additional years as follows:

226Ra- Dose (mRem/year)

0 yr. 1 yr. 10yr.

Ground 3.06E-01 2.96E-01 2.16E-01

Inhalation (w/o radon) 2.07E-OS 2.16E-OS 2.42E-OS

Soils 1.07E-03 1.19E-03 1.74E-03

TOTAL 3.07E-01 2.97E-01 2.18E-01

Dose resulting from consideration of Scenario 1 (2.5 mRem at year zero):

226Ra - Dose .(mRem/year)

Oyr. 1 yr. 10yr.

Ground 2.51E+OO 2.43E+OO 1.77E+OO

Inhalation (w/o radon) 1.71E-04 1.77E-04 1.98E-04

Soils 8.76E-03 9.73E-03 1.43E-02

TOTAL 2.52E+OO 2.44E+OO 1.78E+OO

Dose resulting from consideration of Scenario 2 (2.4 mRem at year zero):

226Ra - Dose (mRem/year)

0 yr. 1 yr. 10yr.

Ground 2.37E+OO 2.25E+OO 1.64E+OO

Inhalation (w/o radon) l.SSE-04 1.64E-04 1.84E-04

Soils 8.13E-03 9.03E-03 1.33E-02

TOTAL 2.38E+OO 2.26E+OO 1.65E+OO

30yr.

1.06E-01

1.76E-OS

1.46E-03

1.07E-01

30yr.

8.68E-01

1.44E-04

1.20E-02

8.80E-01

30yr.

S.OSE-01

1.34E-04

1.11E-02

8.16E~01

The soil cover at the site was not taken into account for this evaluation because the initial calculation of dose was sufficiently low. Appendix J presents the RESRAD 6.5 dose assessment reports.

5.3 Onsite Worker Dose

During remediation activities with the potential to cause airborne radioactivity air sampling was performed. Both general area air samples and personal lapel air sampling was performed. All of the results wer.e counted for gross alpha activity and the results were compared directly to the derived air conce11tration (DAC) limit for 226Ra of 3E-10 !lCi/ml, the concentration which if breathed continuously for one occupational year (2,000

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hours) would result in 5,000 mRem of exposure. The highest minimum detectable concentration calculated for any of the air samples was 6.2 E-13 j..LCifml, orders of magnitude lower than the limit All of the air sample results were less than 1% of the derived air concentration ( < 3E-12 j..LCi/ml). The very low air activity concentrations combined with the limited hours worked doing remediation resulted in no measurable exposure to any of the workers. Appendix G presents the air monitoring data collected during removal action work activities.

6.0 CONCLUSION

Reasonable efforts were made to remediate the Dudley Blvd site. A series of multiple excavations (both machine and manual), using field and on-site laboratory measurements to guide the excavation in order to remove all readily-identifiable 226Ra contamination. A total volume of 120 cubic yards of asphalt and soil were removed and disposed at Clean Harbors in Deer Trail Colorado. No radioactive waste was generated as a result of this FSSR. The Occupational Derived Air Concentration for 226Ra was not exceeded during air monitoring. The site has been backfilled and paved.

The excavation has reduced residual radioactivity sufficiently to allow release of the site for unrestricted use. According to the DQOs in Section 3.1.2, the land area is recommended for unrestricted release if statistically evaluated residual radiological contamination does not exceed ·the applicable release criteria/DCGL levels listed in Section 2.0 ofthis document The mean concentration of226Ra remaining at the site was 0.85 pCijg which is less than the remedial action objective of2.0 pCijg. No individuai 226Ra concentration exceeded the design a priori Elevated Measurement Comparison (EMC) criteria of 3.84 pCijg. Based upon an evaluation of the onsite vs."offsite data, two additional scenarios were considered to provide a more conservative evaluation. Under all scenarios evaluated, the survey unit passes the Wilcoxon Rank Sum Test for a DCGL of 1.2 pCi/g. Surfaces of items remaining at the site meet surface release criteria. Future dose in excess of background was determined to be less than 2 millirem per year. Additional excavation would have been increasingly difficult because it would have involved detecting ever smaller differences between contaminated soil and background in near real time. The probability of excavating and disposing of clean soil would have increased with each successive lift The benefits in terms of reduced dose and risk would have been minimal. Therefore, the levels of residual radioactivity at this site are as low as reasonably achievable. A reasonable effort has been made to remove the residual radioactive contamination from this site. For these reasons, the Air Force Real Property Agency believes that this site is suitable for release for unrestricted use, and is using,this FSSR is being used to request removal of the Dudley Blvd site from the AF RIC permit #CA-00366-00/02.

7.0 REFERENCES

Air Force. "Air.Force Real Property Agency Position on Radiation Background Llevels and Cleanup Goals at the Former McClellan Air Force Base." 2010.

Cabrera Seririces. Final Revised Reference Area Final Status Survey Report Final, Las Vegas, Nevada: Cabrera Services, 2004.

CH2M Hill. Dudle Blvd Non- Time Critical Removal Action Work Plan. Work Plan, McClellan, CA: CH2M Hill, 2011.

Environmental Dimensions, inc. Final Status Survey Plan Field Sampling Plan, Dudley Radiological Removal Action. WorkPlan, Oak Ridge, TN: EDi, 2011.

U.S. Environmental Protection Agency (EPA). "Multi Agency Radiation Survey and Site Investigation Manual (MARSSIM)." 402-R-97-016, Revision 1. 2000 .

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•• I

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APPENDIX A

FIGURES

•

•

LEGEND:

SURVEY UNIT BOUNDARY

• + BOUNDARY LOCATIONS 0

j

tN

20 40

SCALE: 1" = 40'

b

d

e

VICINITY MAP

DUDLEY BLVD

DUDLEY BOULEVARD SITE AND REMOVAL ACTION BOUNDARIES

FIGURE 1

DUDLEY BOULEVARD McCLELLAN AIR FORCE BASE SACREMENTO,CA

•

•

•

Northwest Comer~ /Northeast Comer N:365793 N:365793

E:2166597 E:2166637 + + ~ J '.tc"'t:·.... .: . : :. · .. :· . : ~. ! : • . : . . : ~ . . .·. : ~ '. . . . . . . ii Ji ,::: ••• :~ ·' I : ! ! f : ·~ : : : : ~ :

\,:, ):· :::: .. 'l ... .. :·.•: . ,,,·:::=~=· . . ( ·. . . . : . .. ·::-. :·. I ~~ I .• • • :~ : •

I ' •• • :::: ' . . . . . . . l ~ i 1 i ~ ~ ~~ ~ ~

l• I I I • •: .r .: • •

I :l• • • • • • I ' : • • • • • : ' ' \. . ..... I \ ., ~: • • i'•\ ..... ;: }I J J 1 ~·! J ~ ~ ~

u.:!IHHn ij i,~ 1 L:~ n.: t u 1 ... . :. . . . . ~r l ! ,: i : ! ·. : : ._ :: I I ~ : : • : : ! •

I . ! :: . . \ : . . : I I !! ! : \ i •: : ! ~.· :: : : ~ ·,· : : : • • •• • • • • • • • . . ~' : : : .. · . : :

I :1 :~ : ! i) : i : I• !: :i • • : •. • • • » = d : : I. I. :: :

Southwe~~i~~:~~ ~~~i! ~\l U ~ 1 H :~ ; • • • • • 1 1 • • •• / Southeast Comer

E:2166597 + .._..., :! .• t •• 1• • ... w - •• • •• ~. • N:365683

LEGEND:

CPM- COUNTS PER MINUTE

DATA RANGES (CPM):

• 2221-3031 3032-3193

• 3194-3248

0 8 16

SCALE: 1" = 16'

c-• + E:2166637

BACKGROUND REFERENCE AREA GAMMA WALKOVER SURVEY

FIGURE 2

DUDLEY BOULEVARD McCLELLAN AIR FORCE BASE

SACRAMENTO, CA

•

•

•

LEGEND :


CPM COUNTS PER MINUTE

DATA RANGES (CPM):

• 1412-3295 3296-3585

• 3586 - 3997

0 15 30

SCALE: 1" = 30'

SU1 FINAL STATUS GAMMA WALKOVER SURVEY

FIGURE 3


SACRAMENTO,CA

•

•

•

LEGEND:


CPM COUNTS PER MINUTE

DATA RANGES (CPM) :

• 2187-3304 3305-3577

•

0 15 30

SCALE: 1" = 30'

• • '-"""

POST ADDITIONAL REMOVAL ACTION GAMMA WALKOVER SURVEY

FIGURE4


SACRAMENTO,CA

• -111, (0.63)

SU1-107, (0.89)

•

NOTE· ALL DATA PRESENTED ARE FROM ON SITE • LABORATORY ANALYSIS

LEGEND :


PLANNED EXCAVATION AREAS

TARGET AREAS

CONSTRUCTION FENCE

EXISTING FENCE •

• • SAMPLE LOCATION s SAND TRENCH

181 1m

PRA PAVEMENT REMOVAL AREA •

tN 0 15 30

SCALE: 1" = 30'

TELEPHONE POLE, 12" DIAMETER

MANHOLE. 30" DIAMETER

STORM DRAIN JUNCTION BOX

STORM DRAIN INLET

CONCRETE PHONE UTILITY BOX

CONSTRUCTION TRAILER

SU1-112, (0.99)

SU1-110, (0.73)

<( UJ

SU1-109, (0.93) 0:::: <(

(.!) z z ~ SU1-106, (1.30) I-

SU1-104, (0.64) z <( 0:::: I-.....1 <( ()

SU1-1 02, (0. 70)

FINAL STATUS SYSTEMATIC SAMPLE LOCATIONS

(Ra-226 [609 keV], pCi/g) FIGURE 5


SACRAMENTO,CA

•

SU1-119-B, (0.83)

• SU1-115-P, (0.99)

NOTE· ALL DATA PRESENTED ARE FROM ONSITE . LABORATORY ANALYSIS

LEGEND :



TARGET AREAS

CONSTRUCTION FENCE

EXISTING FENCE • • SAMPLE LOCATION s

• SAND TRENCH 181 [lD

PRA PAVEMENT REMOVAL AREA

tN

0 15 30

SCALE: 1" = 30'


MANHOLE, 30" DIAMETER


STORM DRAIN INLET


( I

SU1-118-B, (0.87)

<( UJ Q:: <( (.9 z z <( Q:: ..... z <( Q:: ..... .....J <( 0

FINAL STATUS PROFESSIONAL AND BIASED SAMPLE LOCATIONS

(Ra-226 [609 keV], pCilg) FIGURE 6


SACRAMENTO, CA

•

•

NOTE· ALL DATA PRESENTED ARE FROM ONSITE . LABORATORY ANALYSIS

LEGEND :

SURVEY UNIT BOUNDARY PLANNED EXCAVATION AREAS

TARGET AREAS CONSTRUCTION FENCE

EXISTING FENCE • • SAMPLE LOCATION s • SAND TRENCH 181 liD


tN

0 15 30

SCALE: 1" = 30'




STORM DRAIN INLET


MDB-043-C, (1 .18)

MDB-044-C, (0.86)

POST ADDITIONAL REMOVAL ACTION SAMPLE LOCATIONS



SACRAMENTO,CA

<( w 0:: <( (.!) z z ~ 1-z ~ 1-.....J <( u

•

•

•

1-116-B, (0.77)

'(1.00) SU1-108, (1.38)

SU1-107, (0.89)

SU1-119-B, (0.83)

SU1-115-P, (0.99)

SU1-1

NOTE· ALL DATA PRESENTED ARE FROM ON SITE . LABORATORY ANALYSIS

LEGEND :



TARGET AREAS

CONSTRUCTION FENCE

EXISTING FENCE • •+• SAMPLE LOCATION s SAND TRENCH

181 liD


tN

0 15 30

SCALE: 1" = 30'




STORM DRAIN INLET


CONSTRUCTION TRAILER

SU1-118-B, (0.87)

SU1-110, (0.73)

SU1-109, (0.93)

MDB-043-C, (1 .18)

MDB-044-C, (0.86)

SU1-106, (1.30)

SU1-104, (0.64)

SU1-102, (0.70)

FINAL CONDITION SAMPLE LOCATIONS



SACRAMENTO,CA

<( w rx: <( C) z z ~ 1--z <( rx: 1--....J <( u

•

•

•

NOTE· ALL DATA PRESENTED ARE FROM ON SITE • LABORATORY ANALYSIS

LEGEND : SURVEY UNIT BOUNDARY

(1 .3)

(0.6) (0.9) (0.7)

(0 .8)

(0.8)

(1(8)7)(1 .1)

. (0.9)

(1 .1) (0.8)

(1 .3)

(0.8)

( .9) (0.8)

(0 .6)

.6)

(0.5)

(0.7)

(0.7)

0 12.5 25

SCALE: 1" = 25'

(0.7)

FINAL CONDITION POSTING PLOT



SACRAMENTO,CA

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