HRS DOCUMENTATION RECORD
-- REVIEW COVER SHEET

Name of Site: Wolff

- Alport Chemical Company
CERCLIS ID No.: NYC200400810 Date Prepared: December 2013
Contact Persons
Site Investigation: Dennis Munhall (212) 637

- 4343 U.S. Environmental Protection Agency (EPA) New York, NY
Documentation Record: James Desir (212) 637

- 434 2 U.S. Environmental Protection Agency (EPA) New York, NY Pathways, Components, or Threats Not Scored The ground water migration , surface water migration , and soil exposure pathways were not scored because the listing decision is not affected significantly by those pathways. The site score is sufficient to list the site on the air migration pathway score. The effects on the ground water migration pathway are unknown. During a 2009 investigation, d ownhole gamma logging indicated that soil contamination extends to 20 feet below ground surface (bgs) and possibly deeper ; this deep contamination is believed t o result from soluble thorium that could be highly mobile in the subsurface [Ref. 5, pp. 38

- 43, 47 , 57 ]. Ground water samples could not be collected during the 2009 investigation because ground water was not encountered in on

- site soil borings or monitori ng wells completed to a maximum depth of 3 7 feet bgs [Ref. 5, p. 23; 2 9, p. 15; 30, pp. 7- 10, 18]. Ground water is expected to be present at approximately 50

- 60 feet below ground surface at the site [Ref. 2 9, pp . 1 5- 16, 61 ].
The surface water migration a nd soil exposure pathways are adversely affected , as the information in the HRS documentation record indicates. There is observed soil contamination at and around the property formerly occupied by Wolff

- Alport Chemical Company ( WACC ) and under neighboring streets and sidewalks where workers, customers, and pedestrians have been observed by EPA (see Section 2.2 of this HRS documentation record ) [ Ref. 19, pp. 30

- 33 ] In addition, WACC discharge d its thorium waste to the sewer system until 1947, a nd recent investigations have indicated that residual contamination still exists in or around the sewer lines downstream of the facility. During periods of heavy flow such as rainstorms, c ombined sewer overflows (CSO) discharge from this combined sewer sy stem to Newtown Creek west of the subject property [Ref. 5, pp. 6

- 7, 10; 6, pp. 9

- 11; 12, p p . 2 , 5]. Note: As shown in this HRS documentation record, the Wolff

- Alport Chemical Company site contains radioactive substances. Therefore, the air migration pa thway for the site is evaluated according to HRS Section 6.0, supplemented by HRS Section 7.0. The following air migration pathway factors are evaluated differently for this site than for sites containing only nonradioactive substances: Observed Release, Toxicity, Hazardous Waste Quantity, Nearest Individual, and Population. The difference for the Nearest Individual and Population factors is in the determination of Level I and Level II concentrations [Ref. 1, Section 7.0, Table 7

- 1]. All other air migrat ion pathway factors are not evaluated differently and are not addressed in HRS Section 7.0. The HRS documentation record cites the appropriate sections and tables of the HRS.This page has been left blank intentionally.HRS DOCUMENTATION RECORD

Name of Site: Wolff

- Alport Chemical Company Date Prepared: December 2013
CERCLIS ID: NYC200400810 EPA Region: 2
Street Address of Site: * 1125

- 1139 I rving A venue , Ridgewood, NY 1 1385 County and State: Queens , NY
General Location in the State: border of Brooklyn and Queens Boroughs, New York City Topographic Map: Brooklyn , NY
Latitude: * 40° 41’ 3 3 .6 2” North Longitude: * 73° 54’ 7. 19 ” West
Site Reference Point: Sample location WAC

- SPUR

- 02 (GPS measur e ment within the source area) [Ref. 3, p. 1; 4, p. 1; 5, p. 5 ; 19, p. 8; 27, pp. 1, 3 ; Figure s 4 , 7 of this HRS documentation record ]

* The street address, coordinates, and contaminant locations presented in this HRS documentation record identify the general area in which the site is located. They represent one or more locations EPA considers to be part of the site based on the screenin g information EPA used to evaluate the site for NPL listing. EPA lists national priorities among the known “releases or threatened releases” of hazardous substances; thus, the focus is on the release, not precisely delineated boundaries. A site is defined as where a hazardous substance has been “deposited, stored, disposed or placed, or has otherwise come to be located.” Generally, HRS scoring and the subsequent listing of a release merely represent the initial determination that a certain area may need to be addressed under CERCLA. Accordingly, EPA contemplates that the preliminary description of facility boundaries at the time of scoring will be refined as more information is developed as to where the contamination has come to be located.

Scores Ground Water Pathway Not Scored Surface Water Pathway Not Scored Soil Exposure Pathway Not Scored Air Pathway 100.00
HRS SITE SCORE 50.00

12 WORKSHEET FOR COMPUTING HRS SITE SCORE Wolff

- Alport Chemical Company

S S 2
1. Ground Water Migration Pathway Score (S gw ) Not Scored (from Table 3

- 1, line 13)
2a. Surface Water Overland/Flood Migration Component Not Scored (from Table 4

- 1, line 30)
2b. Ground Water to Surface Water Migration Component Not Scored (from Table 4

- 25, line 28)
2c. Surface Water Migration Pathway Score (S sw ) Not Scored Enter the larger of lines 2a and 2b as the pathway score.
3. Soil Exposure Pathway Score (S s ) Not Scored (from Table 5

- 1, line 22)
4. Air Migration Pathway Score (S a ) 100.00 10,000.00 (from Table 6

- 1, line 12)

5. Total of S 2 gw + S 2 sw + S 2 s + S 2 a 10,000.00

6. HRS Site Score Divide the value on line 5 by 4 and take the square root 50.003 AIR MIGRATION PATHWAY SCORESHEET Wolff

- Alport Chemical Company

AIR MIGRATION PATHWAY Factor Categories & Factors MAXIMUM VALUE VALUE ASSIGNED Likelihood of Release 1. Observed Release 2. Potential to Release: 2a. Gas Potential to Release 2b. Particulate Potential to Release 2c. Potential to Release (higher of lines 2a and 2b) 3. Likelihood of Release (higher of lines 1 and 2c) 550
500 500 500 550 550
not scored not scored not scored 550 Waste Characteristics 4. Toxicity/Mobility 5. Hazardous Waste Quantity 6. Waste Characteristics * * 100 2 100

3 Targets 7. Nearest Individual 8. Population 8a. Level I Concentrations 8b. Level II Concentrations 8c. Potential Contamination 8d. Population (lines 8a+8b+8c) 9. Resources 10. Sensitive Environments: 10a. Actual Contamination 10b. Potential Contamination 10c. Sensitive Environments (lines 10a + 10b) 11. Targets (lines 7+8d+9+10c ) 50

**   **  5
* ** * ** * ** * ** 45
0 6,8 70. 79 not scored 6, 87 0. 79 not scored not scored not scored not scored not scored 6, 91 5. 79 12. AIR PATHWAY SCORE (lines 3 x 6 x 11)/82,500 **** 100 100.00

* Maximum value applies to waste characteristics category. ** Maximum value not applicable *** No specific maximum value applies to factor. However, pathway score based solely on sensitive environments is limited to maximum of 60. **** Do not round to nearest integer.4 REFERENCES
Reference Number Description of the Reference
1. U.S. Environmental Protection Agency (EPA). Revised Hazard Ranking System, Final Rule, 40 CFR 300, Appendix A . Federal Register. December 14, 1990. A complete copy of the rule is a vailable at http://www.epa.gov/superfund/sites/npl/hrsres/index.htm#HRS Rule . [137 pages]
2. EPA. Superfund Chemical Data Matrix (SCDM) – excerpts . Accessed and printed from http://www.epa.gov/superfund/sites/npl /hr sres/tools/scdm.htm on July 2 , 201 3 . [2 6 pages]
3. E PA. S earch S uperfund Site Information, Wolff

- Alport Chemical Company . Accessed and printed from http://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0206479 on June 14, 2012 . [ 1 page ]
4. U.S. Department of the Interior Geological Survey (USGS). Brooklyn Quadrangle, New York, 7.5

- Minute Series (Topographic)

. 2010 . [1 page]
5. Louis Berger & Assoc., PC (LBA)

. Final Draft Radiological Scoping Survey for Former Wolff

- Alport Chemical Corporation Site, 1125

- 1139 Irving Avenue, Queens, New Yor k 11385, DDC Project No. BEGS 2008007

. Prepared for New York City Department of Design and Construction (NYCDDC). August 23, 2010. [287 pages]
6. U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry (ATSDR). Health Consultation, Former Wolff

- Alport Chemical Corporation Site, 1125

- 1139 Irving Avenue, Queens, New York . February 29, 2012. [44 pages]
7. Fiore, James J., Director, Division of Facility and Site Decommissioning Projects, Office of Nuclear Energy, U.S . Department of Energy (DOE). Letter to Dr. L. R. Solon, Director, Bureau of Radiation Control, New York City Department of Health (NYCDOH), with attachment, RE: Wolff

- Alport Chemical Corporation

. September 29, 1987. [8 pages]
8. Cook, R.W., Director of P roduction, DOE. Office Memorandum to Jesse C. Johnson, Manger of Raw Materials, Operations Office, Subject: Thorium Procurement. March 19, 1951. [1 page]
9. New York State Department of Environmental Conservation (NYSDEC). Former Wolff

- Alport Chemical Co mpany, Site Visit Report

. Site v isit date: May 5 -6 , 2007. [9 pages]
10. Morofsky, Basia and Michael Funaro, Environmental Sciences and Engineering, New York City Department of Health and Mental Hygiene (NYCDOHMH). Wolff Alport: Sample Survey Results, Inter ior Limited Gamma Radiation Survey . July 30, 2007. [1 page]
11. NYCDOHMH. Information on Radiation Survey at the Former Wolff

- Alport Chemical Corporation, 1127

- 1129 Irving Avenue, Queens, NY

. September 5, 2007

. [3 pages]
12. Magriples, Nick, On

- Scene Coordi nator, Removal Assessment and Enforcement Section, EPA

. Memorandum to File, Subject: Removal Site Evaluation for Wolff

- Alport Chemical Company, Borough of Queens, Queens County, New York . May 4, 2012. [54 pages]
13. Environmental Data Resources, Inc. (EDR)

. The EDR Radius MapTM Report with GeoCheck ® , Former Wolff

- Alport Chemical Company, 1125 Irving Avenue, Ridgewood, NY 11385, Inquiry Number: 3364844.2s

. July 11, 2012

. [277 pages]5 REFERENCES (continued)
Reference Number Description of the Reference
14. EDR. The EDR

- City Directory Abstract, Former Wolff

- Alport Chemical Company, 1125 Irving Avenue, Ridgewood, NY 11385, Inquiry Number: 3364844.6

. July 11, 2012

. [13 pages]
15. EDR. Certified Sanborn® Map Report, Former Wolff

- Alport Chemical Company, 1125 Ir ving Avenue, Ridgewood, NY 11385, Inquiry Number: 3364844.3

. July 12, 2012

. [53 pages]
16. EDR. The EDR Aerial Photo Decade Package , Former Wolff

- Alport Chemical Company, 1125 Irving Avenue, Ridgewood, NY 11385, Inquiry Number: 3364844. 5. July 1 2 , 2012

. [1 0 pages]
17. EDR. The EDR C hain of Title Report , Former Wolff

- Alport Chemical Company, 1125 Irving Avenue, Ridgewood, NY 11385, Inquiry Number: 3364844. 12

. July 24 , 2012

. [ 70 pages]
18. Schery, S.D., Associate Professor of Physics, Physics Department and Geophysical Research Center, New Mexico Institute of Mining and Technology

. Th oron in the Environment

. Journal of Air & Waste Management Association, Vol. 40, No. 4

. April 1990. [5 pages]
19. Weston Solutions, Inc. (WESTON). Field Logbook and Field Data Sheets, Wolff

- Alport Chemical Company Site, Queens, NY

. June 28, 2012 to September 21, 2012. [ 60 pages]
20. Gilliland, Gerald V. , Senior Technical Manager and Nels R. Johnson , Certified Health Physicist, WESTON. Trip Report, Wolff

- Alport Chemical Company, Document Control No. 1866

- 2A

- BBUS

. November 5, 2012. [ 46 pages]
21. Gilliland, Gerald V ., Senior Technical Manager, WESTON. Project Note to Wolff

- Alport Chemical Company file, with attachments, Subject: Population Factor Evaluation

. June 25, 2013 . [ 154 p ages]
22. Argonne National Laboratory, EVS

. Natural Decay Series: Uranium, Radium, and Thorium

. Human Health Fact Sheet, August 2005 . [ 4 pages]
23. General Electric Company. Fact Sheet, GE Energy, Reuter

- Stokes 131 Environmental Radiation Monitor . 2004. [2 pages]
24. Durridge Company Inc. RAD7 Radon Detector User Manual, Version 7.1.8 . 2012. [69 pages]
25. Gilliland, Ger ald V., Senior Technical Manager, WESTON. Project Note to Wolff

- Alport Chemical Company file, with attachments, Subject: Calculation of Mean Site

- Specific Background Concentration and Standard Deviation, and Determination of Observed Release

. March 1 1 , 2013 . [5 pages]
26. Rö ttger , A. and A. Honig , Physikalisch

- Technische Bundesanstalt (PTB)

. Recent Developments in Radon Metrology: New Aspects in the Calibration of Radon, Thoron and Progeny Devices

. Radiation Protection Dosimetry (2011), p ages 1-7 . April 5, 2011. [7 pages]
27. Gilliland, Ger ald V., Senior Technical Manager, WESTON. Project Note to Wolff

- Alport Chemical Company file, with attachment, Subject: Latitude and Longitude Coordinates

. May 31, 2013 . [ 3 pages]6 REFERENCES (continued)
Reference Number Description of the Reference
28. WESTON. Sampling and Analysis Quality Assurance Project Plan (SAQAPP), Preliminary Ass essment/Site Inspection, Wolff

- Alport Chemical Company Site, Ridgewood, Queens County, New Jersey

. September 2012 . [ 34 pages]
29. LBA. Final Phase I Environmental Site Assessment Report for Former Wolff

- Alport Chemical Corporation Site, 1125

- 1139 Irving Avenue, Queens, New York 11385, DDC Project No. BEGS 2008007 . Prepared for NYCDDC. May 26, 2010. [720 pages]
30. LBA. Final Phase II Environmental Site Investigation Report for Former Wolff

- Alport Chemical Corporation Site, 1125

- 1139 Irving Avenue, Queens , New York 11385, DDC Project No. BEGS 2008007 . Prepared for NYCDDC. August 23, 2010. [373 pages]
31. Environmental Measurements Laboratory (EML), DOE. HASL

- 300, EML Procedures Manual, 28 th Edition – excerpts . February 1997. Accessed and printed on July 1, 2013 from http://www.nbl.doe.gov/htm/EML_Legacy_Website/ProcMan/Start.htm [28 pages]
32. EPA. Soil Screening Guidance for Rad ionuclides: User’s Guide; excerpts

. Office of Solid Waste and Emergency Response , publication E PA/540 -R- 00

- 007 . October 2000 . [2 4 pages]
33. Daly, Eric M., On

- Scene Coordinator, EPA. POLREP #8, Pollution/Situation Report, Wolff

- Alport Radiological Site

. June 3, 2013 . [ 6 pages]7 SS – Site Summary
SITE SUMMARY
The contaminated soil source associated with the Wolff

- Alport Chemical Company ( WACC ) site (CERCLIS ID No. NYC200400810 ) is located at 1125 to 1139 Irving Avenue and 1514 Cooper Avenue in Ridgewood, Queens County, New York, a t the county border with Brooklyn [Ref. 3, p. 1; 4, p. 1 ; 5, pp. 11, 41

- 47 ] ; the location is shown in Figure 1

. The site includes property contaminated with radioactive thorium

- 232 and a n associated contaminant release to the air migration pathway (see Sections 2.2 and 6.1 of this HRS documentation record)

. WACC operated at the property from the 1920 s until 1954, importing monazite sand via a rail spur and extracting rare earth metals from the material [Ref. 5, pp. 141

- 142, 153

- 154 , 175

- 181 ; 17, pp. 9

- 11 ]

. Monazite contains approximately 6% to 8% or more of thorium [Ref. 5, p. 142]

. Until 1947, WACC disposed of the thorium waste from monazite sand processing in the sewer (process liquors) and possibly by burial on the property (waste tailings) [Ref. 5, p p
. 6- 10 ; 6, p p. 8-9 ; 7, pp. 5, 7]

. According to the U.S. Department of Energy (DOE), t he Atomic Energy Commission (AEC) ordered WACC to halt sewer disposal of thorium waste in the fall of 1947 [Ref. 7, p. 5]

. T hereafter, thorium was precipitated as thorium oxalate sludge and sold to the AEC [Ref. 5, p. 153, 175

- 181; 7, p. 5]

. Documents indicate that WACC sold approximately 53,000 pounds and 238 drums of thorium oxalate sludge to the AEC from 1948 to 1954 , and offered 400 pounds of thorium nitrate for sale to the AEC in 1954 [Ref. 5, pp. 13, 153, 175

- 181; 7, p. 5 ; 8, p. 1 ]. The thorium nitrate was reported to be 15 years old when it was offered to the AEC [Ref. 5, p. 176]. During its years of operation, WACC o ccupied three structures under the address of 1127 Irving Avenue [Ref. 5, pp. 16

- 18; 14, p. 12; 15, pp. 48

- 49 ; 17, pp. 9

- 11] . The operation also included two yard areas: one between the former company's buildings facing Irving Avenue, and the other on the eastern end of the property at the north end of Moffat Street [Ref. 5, pp. 16

- 18; 15, pp. 48

- 49; 16, p. 5]

. These former yard areas, now occupied primarily by structures, were reportedly used as staging areas for monazite sands or waste tailings containi ng thorium

- 232 [Ref. 5, pp. 16 -19 ; 12, p. 4]

. WACC did not operate out of 1125 I rving Avenue or 1514 C ooper Avenue, but those properties are affected by the radioactive materials at the site [Ref. 5, pp. 16

- 17, 41

- 47 , 52 ]

. The facility layout circa 1954 and the current property boundaries (i.e., lot lines) are shown in Figure 2

. The nearly triangular subject property affected by contamination , which includes Lots 31 (partial), 33, 42, 44, 46, and 48 of Queens Borough Block 3725 , covers approximately 0.75 acre bound by Irving Avenue to the southwest, Cooper Avenue to the northwest, and a n active cabinet manufacturer to the east [Ref. 5, p. 11]

. C urrent ly , the property is covered primarily with contiguous structures, except that the former rail spur along its eastern edge is an unpaved , vegetated area where the tracks are no longer present [Ref. 5, p. 19; 19, pp. 3

- 5, 30

- 35]

. The buildings contain a delicatessen/grocery, office space, residential apartments, tire shop , and former mini

- ATV shop (1125 Irving Avenue; Lot 46); an auto repair shop and office space (1514 Cooper Avenue; Lot 48); an auto body shop (1127 Irving Avenue; Lot 44); and two warehouse s (1129 Irving Avenue; Lot 42 and 1133

- 1139 Irving Avenue; Lot 33) [ Ref. 5, p. 11; 19, pp. 30

- 35]

. The former rail spur (portion of Lot 31) is mostly vegetat ed and has a fence at both ends , but t he access gates are damaged and the re is graffiti on the backs of the on - source bui ldings; the area is used for storage of large , steel crane equipment [Ref. 12, p. 1; 19, p. 30, 39, 48

- 51]

. The subject property lot boundaries and current uses are depicted in Figure 3

. The site and related thorium

- 232 gamma radiation and daughter products of the thorium

- 232 decay chain may pose a danger to both the large population in the surrounding area and residents, workers, and students in close proximity to the former WACC facility property

. Gamma radiation w as detected along Irving Avenue where t her e is pedestrian and worker traffic. T he neighborhood s surrounding the subject property c ontain light industry, commercial businesses, and residences [Ref. 12, p. 2]

. The sidewalk and street along Irving Avenue are typically filled with vehicles being serviced by the businesses at the propert y [Ref. 12, p. 4; 19, pp. 31

- 33, 37, 40

- 42]

. EPA observed workers, customers, and pedestrians on the sidewalks and streets surrounding the subject property, including a steady stream of customers to the deli/grocery [Ref. 19, pp. 30

- 33]. The intersection of Irving Avenue and Moffat Street (i.e., the south corner of the subject property ) is an active area for trailer parking and unloading [Ref. 12, p. 4; 19, pp. 38, 44

- 45]

. The re are three currently unoccupied apartments over the delicatessen/grocery, and other housing begins across the street on both Cooper and Irving Avenues [Ref. 19, p. 30; 21, p. 2]

. The residential area is densely populated and contains multi

- family homes and apartments , and a public elementary school is located 900 feet to the south west [Ref. 12, p. 2; 19, pp. 3 -5 ; 21, pp. 2

- 4, 153

- 154] , . An active rail line passes within 125 feet southeast of the subject property , and the Cemetery of the Evergreens is present to the east and south on the opposite side of the active rail line [Ref. 4, p. 1; 12, p. 2]

.8 SS – Site Summary
SITE SUMMARY (continued) Radiological surveys by City, State, and Federal agencies have identified radioactivity above background levels within portions of subject property buildings, in soils beneath and around the former WACC facility and adjacent buildings, and above adjacent sidewalks, streets, and sewers [Ref. 5, pp. 5

- 10 , 98

- 118, 131

- 136 ; 9, pp. 1

- 9; 10, p. 1; 11, pp. 1

- 3] . During an investigation by New York City Department of Design and Construction (NYCD DC) in 2009

- 1010, waste tailings consisting of black or gray ash

- like material were found in a contaminated soil layer beneath subject property buildings, beneath sidewalks and asphalt surfaces of Irving Avenue and Moffat Street, and within the surface soi ls of the former rail spur [Ref. 5, pp. 38

- 43]

. The depth of visually

- contaminated soil at the subject property is typically within the top 1 to 4 feet under the pavement or ground surface, however, a lens was reported at 8 to 10 feet beneath the auto bod y shop [Ref. 5, pp. 43, 56]

. Thorium

- 232 concentrations up to 1,133 picocuries per gram (pCi/g) were reported for the soil samples containing waste, while background was reported to be 0.5 pCi/g to 1.0 pCi/g [Ref. 5, pp. 41

- 46]

. The soil screening concen tration for cancer corresponding to that concentration that corresponds to the 10 -6 individual cancer risk for oral (ingestions) exposures of thorium

- 232 is 3.4 pCi/g [Ref. 1, Section 7.3.2; 2, p. 16]. The NYCDDC soil sampling results are depicted in Fig ure 3

. The radioactive decay of t horium

- 232 , which has a half

- life of 14 billion years , proceeds as follows ( radioactive half

- lives in parentheses ) : radium

- 228 (5.8 years), actinium

- 228 (6.1 hours), thorium

- 228 (1.9 years), radium

- 224 (3. 7 days), radon

- 220 (5 6 seconds), polonium

- 216 (0.15 second), lead

- 212 (1 1 hours), bismuth

- 212 (6 1 minutes), polonium

- 212 (310 nano second s) and thallium

- 208 (3 .1 minutes), and lead

- 208 (stable) [Ref. 22, pp. 1, 4 ]. Due to the length of time since processing of the monazite sands (about 60 years or more) , it is reasonable to assume secular equilibrium (i.e., the activities of all radionuclides within the series are nearly equal ) for t he se radionuclides in th e waste materials abandon ed at the site [Ref. 22, p. 1]

. One of the key components of th e thorium

- 232 decay series is radon

- 220, a radioactive gas commonly and hereinafter referred to as thoron , which emanates from surfaces where thorium

- 232 is present [Ref. 18, p. 1 ; 22, pp. 1, 4 ]

. One of the hazard s associated with airborne thoron comes from its radioactive decay products, a large fraction of which remain suspended in the air where they can be inhaled and de posited in the lung s; t he primary health hazard is lung cancer due to alpha particle radiation s from these decay products after they have been deposit ed on the bronchial epithelium of the lung [Ref. 18, p. 3]

. During the NYCDDC investigation at the WACC subject property , thoron was detected in the deli basement at a concentration of 12.7 picocurie s per liter (pCi/L) [Ref. 5, p. 52]

. In September 2012 , the U.S. Environmental Protection Agency collected gamma radiation exposure rate measurements and thoron concentration measurements on and around the perimeter of the source area and at background lo cations [ Ref. 19, pp. 5

- 12; 20, pp. 3 -9]

. The measurement locations are shown in Figure 4

. The gamma radiation exposure rate measurements identified hot spots along the former rail spur and in the sidewalks and streets adjacent to the former facility , as shown in Figure s 5 and 6

. The contaminated area (i.e., the source area) , defined as the extent at which the gamma radiation exposure rates equal or exceed two times the site

- specific background gamma radiation exposure rate , extends throughout most o f the subject property and in some of the street and sidewalk areas , as discussed in Section 2.2 of this HRS documentation record and depicted in Figure 6

. EPA evaluated an observed release for the air migration pathway by collecting real

- time thoron gas concentration measurements at and in the vicinity of the WACC former facility in September 2012

. At selected locations in background areas, above the source material, and outside the boundary of the source area , thoron gas concentration measurements in pC i/L were collected with RAD7 Radon Detectors [Ref. 19, p. 19 ; Ref. 20 , pp. 5

- 12, 23

- 29] . Each thoron measurement location coincided with a gamma radiation exposure rate measurement location to identify its relative location with respect to the source boundary , as shown in Figure 4

. F or radionuclides that occur naturally, observed release for a migration pathway is established when a measured concentration in units of activity ( e.g., pCi/L) is at a level that equals or exceeds a value two standard deviations above the mean site

- specific background concentration for that radionuclide in that type of sample [Ref. 1, Section 7.1.1]. Based on that criterion, t horon gas concentrations at levels s ignificantly above the mean site

- specific background concentration (0. 69 pCi/L) were measured in air above the source material and outside the source boundary at the WACC site , as discussed in Section 6.1.1 of this HRS documentation record shown in Figure 7 . Based on these results, an observed release to the air migration pathway is established, as discussed further in Section 6.1.1.9 SS – Site Summary
SITE SUMMARY (continued)
T he population factor evaluation is based on three factors: Level I concentrations, Level II concentrations, and potential contamination [Ref. 1, Section 6.3.2]

. Level I concentrations are not scored. Level II concentrations are assigned to the actual contamination at each sampling location that meets the criteria for observed release of thoron [Ref. 1, Section 2.5 ; 2, pp. 20

- 21 ]. The single most distant Level II sample location is located within the Greater than 0 to 1⁄4 mile distance category of the air migration pathway [Ref. 1, Section 6.3 , Table 6- 15 ; Figure 8 ] . T he p opulation located anywhere within this furthest Level II distance category is considered as subject to Level II concentrations [Ref. 1, Section 6.3]. B ased on these considerations, more than 6,8 00 residents , student s, and workers within 1⁄4 mile of the sour ce are considered as subject to Level II concentrations (see Section 6.3.2.3 of this HRS documentation record ) . In addition , there are more than 1.8 million residents within 4 miles of the source at the site [Ref. 21, pp. 1

- 4, 6, 14, 42, 88, 148, 154]

. Since October 2012, EPA has conducted additional monitoring and mitigation activities at the WACC subject property and vicinity. Surveys conducted in October and November 2012 confirm ed elevated radiation levels in some areas [Ref. 33, pp. 2

- 3]. In Decem ber 2012 and February 2013, r adon and thoron monitoring in on

- source buildings indicated a few elevated readings [Ref. 33, p p . 3 -4 ]. EPA installed fencing at the site and began shielding portions of the radioactive soil with rock and clean fill in April 2 013 to reduce accessibility of the waste material [Ref. 33, p. 4]. The source and exposures are not wholly contained, and EPA is continuing mitigation activities at the site [Ref. 33, pp. 2

- 5].FIGURE #: DATE: CLIENT NAME: PROJECT: LEGEND: TITLE: Source 1

0 2,000 4,000 1,000

Graphic Scale In Feet

1. National Geographic TOPO! U.S. Geologic Survey (USGS). 7.5 Minute

Series (Topographic) Quadrangles: Brooklyn, NY 1995. 2. Ref. 19, pp. 13-22; 27, pp. 1-3

EPA Wolff-Alport Chemical Company Site
July 2013 1 

### Source Location Map Wolff-Alport Chemical Company Site Ridgewood, Queens County, NYP:\SAT2\Wolff_Alport_Chemical\MXD\2013_07_Report\13366_WAC_Site_Loc.mxd

SOURCES: 

### Site Area " 

### NJ PA NY 

# ®

Perimeter of Source 1Non-WACC Commercial Buildings

WACC Storage Buildings

WACC Yard Areas

FIGURE #: DATE: CLIENT NAME: PROJECT: SOURCES: TITLE: C O

O

P

E

R A V

E

C

O

O

P

E

R

S

T I R

V

I NG A

V

E

M O

F F A T S

T Non-WACC Commercial Buildings WACC Warehouse
WACC Storage Buildings

WACC Yard Areas WACC Kiln-Vat Building

0 150 300 75

Graphic Scale In Feet

1. 1954 Aerial; EDR Report, Inquiry 3364844.5. 2. New York City Department of Finance. Digital Tax Map Online;

http://gis.nyc.gov/taxmap/map.htm. 3. Ref. 5, pp. 18, 39-42.

EPA Wolff-Alport Chemical Company Site
July 2013 2 

### WACC Facility Layout, 1954 Wolff-Alport Chemical Company Site Ridgewood, Queens County, NYP:\SAT2\Wolff_Alport_Chemical\MXD\2013_07_Report\13368_WAC_1954_Aerial.mxd 

# ®

Legend Lot & Block Lines Approximate Extent of Contaminated Soil (NYCDDC, 2010)FIGURE #: DATE: CLIENT NAME: PROJECT: SCALE: TITLE: 0 80 160 40

Graphic Scale In Feet

EPA Wolff-Alport Chemical Company Site
July 2013 3 

### Geographic Representation of Soil Sample Analytical Results from NYCDDC Radiological Scoping Survey (August 2010) Wolff-Alport Chemical Company Site Ridgewood, Queens County, NYP:\SAT2\Wolff_Alport_Chemical\MXD\2013_07_Report\13367_WAC_DDC_Sample_results.mxd 

# ®

Legend ! ( >55 pCi/g ! ( 5-55 pCi/g ! ( < 5 pCi/g ! ( NO DATA Lot & Block Lines Approximate Extent of Contaminated Soil (NYCDDC, 2010) Sources: 1. Bing Maps - Aerial - Image courtesy of the IndianaMap © 2012 Microsoft Corporation © 2010 NAVTEQ © 2. New York City Department of Finance. Digital Tax Map Online;

http://gis.nyc.gov/taxmap/map.htm. 3. Ref. 5, pp. 39-42; 12, p. 2FIGURE #: DATE: CLIENT NAME: PROJECT: SOURCES: TITLE: 0 80 160 40

Graphic Scale In Feet

EPA Wolff-Alport Chemical Company Site
July 2013 4 

### Survey Location Map - September 2012

Wolff-Alport Chemical Company Site Ridgewood, Queens County, NYP:\SAT2\Wolff_Alport_Chemical\MXD\2013_07_Report\13369_WAC_09_2012_Sample_loc.mxd 

# ®

Legend Pressurized Ion Chamber (PIC) Gamma Survey Point " ) RAD7 Thoron and Radon Gas Survey Point Lot & Block Lines Approximate Extent of Contaminated Soil (NYCDDC, 2010)

1. Bing Maps - Aerial - Image courtesy of the IndianaMap © 2012 Microsoft Corporation © 2010 NAVTEQ © 2. New York City Department of Finance. Digital Tax Map Online;

http://gis.nyc.gov/taxmap/map.htm. 3. Ref. 5, pp. 39-42; 12, p. 2; 19, pp. 13-26; 27, pp. 1-3.FIGURE #: DATE: CLIENT NAME: PROJECT: SCALE: TITLE:

0 80 160 40

Graphic Scale In Feet
1. Bing Maps - Aerial - Image courtesy of the IndianaMap © 2012 Microsoft Corporation © 2010 NAVTEQ © 2. New York City Department of Finance. Digital Tax Map Online;

http://gis.nyc.gov/taxmap/map.htm. 3. Ref. 5, pp. 39-42; 12, p. 2; 19, pp. 13-26; 27, pp. 1-3.

EPA Wolff-Alport Chemical Company Site
July 2013 5 

### Field Gamma Reading (cpm) Wolff-Alport Chemical Company Site Ridgewood, Queens County, NYP:\SAT2\Wolff_Alport_Chemical\MXD\2013_07_Report\13370_WAC_Field_Readings.mxd 

# ® Location ID Field Gamma Reading (cpm) WAC

‐ BKG

‐ 01 7307 WAC

‐ BKG

‐ 02 7723 WAC

‐ BKG

‐ 03 7213 WAC

‐ BKG

‐ 04 11579 WAC

‐ BKG

‐ 05 7704 WAC

‐ BKG

‐ 06 7949 WAC

‐ BKG

‐ 07 9513 WAC

‐ SPUR

‐ 01 145524 WAC

‐ PER

‐ 01 13607 WAC

‐ PER

‐ 02 25615 WAC

‐ PER

‐ 03 15919 WAC

‐ PER

‐ 04 24289 WAC

‐ PER

‐ 05 16814 WAC

‐ PER

‐ 06 36965 WAC

‐ PER

‐ 07 15155 WAC

‐ PER

‐ 08 22012 WAC

‐ PER

‐ 09 22625 WAC

‐ PER

‐ 10 15742 WAC

‐ PER

‐ 11 21622 WAC

‐ PER

‐ 12 23450 WAC

‐ PER

‐ 13 13341 WAC

‐ SPUR

‐ 02 147135 WAC

‐ PER

‐ 14 22090 WAC

‐ PER

‐ 15 46397 WAC

‐ PER

‐ 16 18126 WAC

‐ PER

‐ 17 26291 WAC

‐ PER

‐ 18 33171 WAC

‐ PER

‐ 19 15262 WAC

‐ IRV

‐ 20 12159 WAC

‐ IRV

‐ 21 19866 WAC

‐ IRV

‐ 22 15223 WAC

‐ IRV

‐ 23 22989 WAC

‐ IRV

‐ 24 14484 WAC

‐ IRV

‐ 25 39322 WAC

‐ IRV

‐ 26 20768 WAC

‐ IRV

‐ 27 24608 WAC

‐ IRV

‐ 28 14108 WAC

‐ IRV

‐ 29 15972 WAC

‐ IRV

‐ 30 27293 WAC

‐ IRV

‐ 31 38382 WAC

‐ IRV

‐ 32 23960 WAC

‐ IRV

‐ 33 15106 WAC

‐ IRV

‐ 34 36966 WAC

‐ IRV

‐ 01 19794 WAC

‐ IRV

‐ 02 65943 WAC

‐ IRV

‐ 03 40336 WAC

‐ IRV

‐ 04 27228 WAC

‐ IRV

‐ 05 22360 WAC

‐ IRV

‐ 06 15595 WAC

‐ IRV

‐ 07 19487 WAC

‐ IRV

‐ 08 9067 WAC

‐ MOF

‐ 01 18145 WAC

‐ MOF

‐ 02 35783 WAC

‐ MOF

‐ 03 25565 WAC

‐ MOF

‐ 04 33719 WAC

‐ MOF

‐ 05 26435 WAC

‐ MOF

‐ 06 49775 WAC

‐ MOF

‐ 07 38888 WAC

‐ MOF

‐ 08 19855 WAC

‐ MOF

‐ 09 19312 WAC

‐ MOF

‐ 10 15132 WAC

‐ MOF

‐ 11 13312 WAC

‐ IRV

‐ 10 437849 WAC

‐ COP

‐ 01 8827 WAC

‐ COP

‐ 02 8366 WAC

‐ COP

‐ 03 11248 WAC

‐ COP

‐ 04 8554 WAC

‐ MOF

‐ 12 16006 WAC

‐ MOF

‐ 13 24764 WAC

‐ MOF

‐ 14 17159 Legend Pressurized Ion Chamber (PIC) Gamma Survey Point " ) RAD7 Thoron and Radon Gas Survey Point Lot & Block Lines Approximate Extent of Contaminated Soil (NYCDDC, 2010) Note: 1. cpm = counts per minute, as measured with Ludlum

2221/44-10 NaI scintillation detector.FIGURE #: DATE: CLIENT NAME: PROJECT: SOURCES: TITLE:

EPA Wolff-Alport Chemical Company Site July 2013 6 

### Gamma Radiation Exposure Rate (μR/hr) Wolff-Alport Chemical Company Site Ridgewood, Queens County, NYP:\SAT2\Wolff_Alport_Chemical\MXD\2013_07_Report\13371_WAC_Gamma_Exposure.mxd 

# ®

Location ID Gamma Radiation Exposure Rate

(μR/hr) WAC

‐ BKG

‐ 01 8.7 WAC

‐ BKG

‐ 02 9.5 WAC

‐ BKG

‐ 03 8.4 WAC

‐ BKG

‐ 04 11.4 WAC

‐ BKG

‐ 05 9.3 WAC

‐ BKG

‐ 06 9.1 WAC

‐ BKG

‐ 07 9.8 WAC

‐ SPUR

‐ 01 114.5 WAC

‐ PER

‐ 01 12.3 WAC

‐ PER

‐ 02 21.8 WAC

‐ PER

‐ 03 14.8 WAC

‐ PER

‐ 04 18.3 WAC

‐ PER

‐ 05 14.3 WAC

‐ PER

‐ 06 26.7 WAC

‐ PER

‐ 07 13.7 WAC

‐ PER

‐ 08 20.3 WAC

‐ PER

‐ 09 19.8 WAC

‐ PER

‐ 10 13.9 WAC

‐ PER

‐ 11 19.2 WAC

‐ PER

‐ 12 19.8 WAC

‐ PER

‐ 13 12.9 WAC

‐ SPUR

‐ 02 119.9 WAC

‐ PER

‐ 14 18.9 WAC

‐ PER

‐ 15 33.4 WAC

‐ PER

‐ 16 16.8 WAC

‐ PER

‐ 17 22.9 WAC

‐ PER

‐ 18 25.9 WAC

‐ PER

‐ 19 14.1 WAC

‐ IRV

‐ 20 11.3 WAC

‐ IRV

‐ 21 16.7 WAC

‐ IRV

‐ 22 12.5 WAC

‐ IRV

‐ 23 19.8 WAC

‐ IRV

‐ 24 12 WAC

‐ IRV

‐ 25 23.9 WAC

‐ IRV

‐ 26 15.9 WAC

‐ IRV

‐ 27 17.7 WAC

‐ IRV

‐ 28 13.1 WAC

‐ IRV

‐ 29 13.9 WAC

‐ IRV

‐ 30 22.5 WAC

‐ IRV

‐ 31 28.4 WAC

‐ IRV

‐ 32 17.1 WAC

‐ IRV

‐ 33 12.3 WAC

‐ IRV

‐ 34 24.2 WAC

‐ IRV

‐ 01 18.5 WAC

‐ IRV

‐ 02 49.5 WAC

‐ IRV

‐ 03 33.7 WAC

‐ IRV

‐ 04 25 WAC

‐ IRV

‐ 05 19.1 WAC

‐ IRV

‐ 06 14.6 WAC

‐ IRV

‐ 07 16.3 WAC

‐ IRV

‐ 08 10 WAC

‐ MOF

‐ 01 15.7 WAC

‐ MOF

‐ 02 30.9 WAC

‐ MOF

‐ 03 23.8 WAC

‐ MOF

‐ 04 28.3 WAC

‐ MOF

‐ 05 22.3 WAC

‐ MOF

‐ 06 42.2 WAC

‐ MOF

‐ 07 29.8 WAC

‐ MOF

‐ 08 19 WAC

‐ MOF

‐ 09 17.7 WAC

‐ MOF

‐ 10 14.6 WAC

‐ MOF

‐ 11 13 WAC

‐ IRV

‐ 10 2166.3 WAC

‐ COP

‐ 01 10 WAC

‐ COP

‐ 02 9.4 WAC

‐ COP

‐ 03 11.4 WAC

‐ COP

‐ 04 9.7 WAC

‐ MOF

‐ 12 15.1 WAC

‐ MOF

‐ 13 19 WAC

‐ MOF

‐ 14 16.3 Legend Pressurized Ion Chamber (PIC) Gamma Survey Point Background Sample Location Sample Location with Result < 2x Background Sample Location with Result > 2x Background " ) RAD7 Thoron and Radon Gas Survey Point Lot & Block Lines Perimeter of Source 1 (Based on Gamma Exposure Rates, September 2012) Other Possible Source Area (Based on Gamma Exposure Rates, September 2012)

1. Bing Maps - Aerial - Image courtesy of the IndianaMap © 2012 Microsoft Corporation © 2010 NAVTEQ © 2. New York City Department of Finance. Digital Tax Map Online; http://gis.nyc.gov/taxmap/map.htm. 3. Ref. 12, p. 2; 19, pp. 13-22; 27, pp. 1-3. Note: 1. μR/hr = microRoentgens per hour, as measured with Reuter-Stokes RSS-131 pressurized ion chamber. 0 80 160 40

Graphic Scale In FeetFIGURE #: DATE: CLIENT NAME: PROJECT: SOURCES: TITLE: 0 80 160 40

Graphic Scale In Feet

EPA Wolff-Alport Chemical Company Site
July 2013 7 

### Thoron Concentrations (pCi/L) Wolff-Alport Chemical Company Site Ridgewood, Queens County, NYP:\SAT2\Wolff_Alport_Chemical\MXD\2013_07_Report\13372_WAC_Thoron_Samples.mxd 

# ® Field ID Thoron w/ Uncertainty (pCi/L) WAC

‐ BKG

‐ 01 0.00 ± 0.56 WAC

‐ BKG

‐ 04 0.33 ± 0.90 WAC

‐ BKG

‐ 05 0.00 ± 0.56 WAC

‐ BKG

‐ 05A 0.00 ± 0.66 WAC

‐ BKG

‐ 06 0.17 ± 0.80 WAC

‐ IRV

‐ 10 0.33 ± 0.90 WAC

‐ IRV

‐ 31 1.12 ± 1.12 WAC

‐ PER

‐ 01 2.98 ± 1.77 WAC

‐ PER

‐ 05 3.94 ± 1.80 WAC

‐ PER

‐ 07 2.15 ± 1.57 WAC

‐ PER

‐ 13 3.80 ± 1.77 WAC

‐ PER

‐ 16 10.3 ± 2.71 WAC

‐ PER

‐ 18 8.61 ± 2.74 WAC

‐ PER

‐ 19 2.48 ± 1.65 WAC

‐ SPUR

‐ 01 61.8 ± 6.19 WAC

‐ SPUR

‐ 02 366 ± 16.1 WAC

‐ SPUR

‐ 02

‐ A 301 ± 13.5 WAC

‐ SPUR

‐ 02

‐ ELEV 6.19 ± 2.17

Legend " ) RAD7 Thoron and Radon Gas Survey Point Lot & Block Lines Perimeter of Source 1 (Based on Gamma Exposure Rates, September 2012) Other Possible Source Area (Based on Gamma Exposure Rates, September 2012)

1. Bing Maps - Aerial - Image courtesy of the IndianaMap © 2012 Microsoft Corporation © 2010 NAVTEQ © 2. New York City Department of Finance. Digital Tax Map Online;

http://gis.nyc.gov/taxmap/map.htm. 3. Ref. 5, pp. 39-42; 12, p. 2; 19, pp. 13-26; 27, pp. 1-3. Note: 1. pCi/L = picocuries per liter, as measured with RAD7

Radon Detector.FIGURE #: DATE: CLIENT NAME: PROJECT: LEGEND: TITLE: Source 1 1/4 Mile

0 500 1,000 250

Graphic Scale In Feet SOURCES: 1. National Geographic TOPO! U.S. Geologic Survey (USGS). 7.5 Minute

Series (Topographic) Quadrangles: Brooklyn, NY 1995. 2. U.S. Department of Commerce, U.S. Census Bureau, Geography Division.

TIGER/Line Shapefile, 2010, 2010 state, New York, 2010 Census Block State-based. http://www.census.gov/geo/www/tiger. Downloaded March 2013. 3. Ref. 19, pp. 13-22; 21, pp. 1, 154; 27, pp. 1-3.

EPA Wolff-Alport Chemical Company Site
July 2013 8 

### Quarter-Mile Radius Map Wolff-Alport Chemical Company Site Ridgewood, Queens County, NYP:\SAT2\Wolff_Alport_Chemical\MXD\2013_07_Report\13373_WAC_quarter_mile.mxd 

# ®

Perimeter of Source 1 2010 Census Blocks18 SD

- Characterization and Containment Source No.: 1

SOURCE DESCRIPTION

2.2 SOURCE CHARACTERIZATION
Number of the source: 1 Source Type of the source: Contaminated Soil
Name and description of the source: Residual W aste Materials
Source 1 is soil contaminated with residual waste materials left behind by facility operations, as identified in the results of the 2009

- 2010 NYCDDC investigation. During the NYCDDC investigation, soil borings, samples, and downhole gamma logging were used to identify residual waste materials and s oil contamination at the subject property [Ref. 5, pp. 6

- 9]

. Waste tailings consisting of black or gray ash

- like material were found in a contaminated soil layer beneath subject property buildings, beneath sidewalks and asphalt surfaces of Irving Avenue and Moffat Street, and within the surface soils of the former rail spur [Ref. 5, pp. 43, 56 ]

. The depth of contaminated soil at the subject property is typically within the top 1 to 4 feet under the pavement or ground surface, and a lens was reported at 8 to 10 feet beneath the auto body shop [Ref. 5, p. 43]

. During the 2009

- 2010 NYCDDC investigation, f ourteen subsurface samples were collected under the buildings, while 21 surface samples and 14 subsurface samples were collected from exterior areas [Ref. 5, pp. 38

- 40 , 213, 216

- 217, 220, 287 ]. The soil samples were analyzed using HPGe (high purity germanium) gamma spectroscopy at CoPhysics Corporation , and t he 911 kilo

- electron volt (keV) gamma ray line from Ac tinium

- 228 was used for thorium

- 232 determination [Ref. 5, pp. 53, 81

- 84 ; 31 , pp. 10

- 11, 25

- 26 ] . The method used by the laboratory is equivalent to EPA

- approved Method GA

- 01

- R,”Gamma Radioassay” from the DOE HASL

- 300 Manual dated 1997 [Ref. 5, p. 53; 31 , pp. 10

- 22 ]

. The results were reported in units of pCi/g wet weight (in situ concentration) , and each analytical result was presented with an associated uncertainty level that represented one standard deviation [Ref. 5, pp. 45

- 46, 53, 81

- 84]. Detection limits and q uantitation limits were not presented with the sample analytical results [Ref. 5, pp. 45

- 46, 81

- 84]. Quality controls included duplicate, blank, and reference samples [Ref. 5, pp. 53

- 54 ]. The deionized water blank used for quality control showed a thorium

- 232 result of 0.03 ± 0.01 pCi/g, and the reference sample results were below the expected results, possibly indicating low bias for the associated field sample results [Ref. 5, pp. 53

- 54].
Thorium

- 232 activity concentrations up to 1,133 pCi/g were reported for the soil samples col lected from the subject property , including a concentration of 477 pCi/g in the deeper lens [Ref. 5, pp. 39

- 42, 45

- 46, 81

- 84]

. Site

- specific background samples were not collected during the investigation [Ref. 5, p. 287]. Based on work at other radiation sites in the region, the range of thorium background concentrations in northeastern soil was reported to be 0.5 pCi/g to 1.0 pCi/g and the higher value was assumed as the site background level [Ref. 5, p p . 41 , 287 ]. NYCDDC used a guideline of 5 pCi/g above this background level to depict contaminated areas at the WACC site , based on EPA’s prior use of that guideline as a cleanup level at Superfund sites [Ref. 5, pp. 24

- 25, 42]. The soil sampling results from the NYCDDC investigation are presented below in Table 1 , and the approximate extent of contamination based on the se results is depicted in Figure 3

.19 SD

- Characterization and Containment Source No.: 1

TABLE 1. SOIL SAMPLE RESULTS Location Depth (ft bgs) Date Lab ID Wet Mass (g) Dry Mass (g) Throrium

- 232 (pCi/ g ) * Reference 

### A1A 0.5

- 1.5 12/16/09 725

- 06 136.1 82.4 21.2 ± 1.1 5, pp. 38

- 46, 53

- 54, 81

- 84 

### A2A 8.5

- 9 12/16/09 725

- 04 142.0 123.2 476.9 ± 28.2 A2B 0.5

- 1 12/16/09 725

- 01 121.2 101.2 1 , 133.4 ± 68.4 A3A 0.5

- 1.5 12/16/09 725

- 03 169.9 128.8 202.3 ± 11.8 A3B 0.5

- 1.5 12/16/09 725

- 05 361.9 329.8 424.7 ± 22.1 A3C 0.5

- 1.0 12/13/09 725

- 13 188.9 163.3 73.4 ± 3.9 A4A 0.5

- 1.5 12/16/09 725

- 02 281.8 251.2 169.6 ± 9.7 A5A 1

- 1.5 12/13/09 725

- 08 323.2 279.4 44.6 ± 2.4 A5B 0.5

- 1.5 12/16/09 725

- 11 191.1 170.8 77.4 ± 4.2 A6A 0.5

- 1.0 12/16/09 725

- 12 196.7 181.4 13.2 ± 0.8 A6B 0.5

- 1.5 12/12/09 725

- 10 410.2 375.6 45.2 ± 2.5 A6C 0.5

- 1.5 12/12/09 725

- 07 298.0 275.4 75.9 ± 4.1 B1B 0

- 0.5 11/12/09 716

- 05 268.7 250.9 10.4 ± 0.6 B1D 2"

- 1' 12/12/09 725

- 16 190.0 184.8 15.2 ± 0.9 B1S2 surface 12/16/09 725

- 40 422.0 356.5 13.7 ± 0.7 B2A 0

- 1 12/13/09 725

- 15 311.3 275.1 28.8 ± 1.5 B2B 0

- 1 12/12/09 725

- 17 373.3 312.4 99.5 ± 5.2 B2E 2

- 2.5 12/12/09 725

- 20 314.1 268.7 207.8 ± 10.5 B2F 0

- 0.5 12/12/09 725

- 19 302.6 255.7 20.7 ± 1.1 B2S10 surface 12/16/09 725

- 31 293.1 272.0 10.9 ± 0.7 B2S14 surface 12/16/09 725

- 35 350.8 294.4 8.2 ± 0.5 B2S2 surface 12/16/09 725

- 23 196.7 125.1 471.8 ± 24.1 B2S3 surface 12/16/09 725

- 24 202.7 148.3 9.7 ± 0.6 B2S4 surface 12/16/09 725

- 25 296.1 249.3 25.3 ± 1.3 B2S5 surface 12/16/09 725

- 26 263.1 198.6 17.9 ± 0.9 B2S6 surface 12/16/09 725

- 27 257.5 201.5 12 ± 0.7 B2S7 surface 12/16/09 725

- 28 229.7 172.5 18.3 ± 1 B2S8 surface 12/16/09 725

- 29 296.3 224.2 17 ± 0.9 B2S9 surface 12/16/09 725

- 30 283.4 216.7 12.1 ± 0.7 B3B 0

- 1 11/12/09 716

- 02 335.3 314.4 143.7 ± 7.2 B3C 0

- 1 11/12/09 716

- 03 323.4 302..2 40.6 ± 2.1 B3D 0

- 0.5 11/12/09 716

- 07 457.1 416.1 10.2 ± 0.6 B3S1 surface 12/16/09 725

- 38 531.4 467.7 13.7 ± 0.8 B3S2 surface 12/16/09 725

- 39 467.9 418.6 7.8 ± 0.4 M

- 2 0.5 07/24/09 692

- 1 291.1 273.0 38.2 ± 2.2 pCi/g = Picocuries per gram * The detection limits and quantitation limits were not presented in the available report or its attachments [Ref. 5, pp. 45

- 46, 81

- 84, 286

- 287].20 SD

- Characterization and Containment Source No.: 1
During the NYCDDC investigation , g amma radiation levels above the background range of 6 μR /hr to 10 μR /hr were recorded throughout most of the subject property [Ref. 5, pp. 34

- 37]

. Interior gamma measurements above background were recorded in the auto body shop (formerly the WACC kiln

- vat operations building a nd adjoining yard), warehouses (formerly a WACC operations building and adjoining yard), and deli basement, with the highest reading ( 500 μR /hr ) in the auto body shop [Ref. 5, pp. 28, 36

- 37 , 63 ]

. The highest exterior gamma measurement was recorded near the curb in front of the auto body shop [Ref. 5, pp. 28, 34

- 35]

. Downhole gamma logging also indicated the presence of contamination to depths up to 20 feet beneath the auto body shop, and acidic odors were reported within th o se deeper borings ; however, w aste tailings are absent at these depths and this deeper contamination is believed to stem from solubilized thorium that leached down throu gh the pre

- existing sandy soil [Ref. 5, pp. 43

- 47]. In September 2012, EPA used a Reuter

- Stokes RSS

- 131 Pressurized Ion Chamber (PIC) to collect gamma radiation exposure rate measurements at hot spots within the source area, around the perimeter of Source 1, and at background locations [Ref. 19, pp. 5

- 22; 20, pp. 3

- 7, 20 ; 23, pp. 1

- 2]. Concurrently, EPA measured a one - minute gamma count rate at each location with a Ludlum Model 2221/44

- 10 , 2- inch by 2

- inch , sodium iodide (2x2 NaI) scintillation detector that was configured to mimic the response of the PIC [Ref. 19, pp. 5- 22 ; 20, pp. 3

- 4]

. The PIC and scintillation detector systems collected data at a height of one meter above the ground surface [Ref. 20, p. 3]

. The measurement locations are shown in Figure 4

. The primary objective of the EPA gamma survey was to delineate the source area by mapping the boundary lin e where gamma radiation exposure rate s equal two times the site

- specific background gamma radiation exposure rate [Ref. 20, pp. 3 -4 ; 2 8 , pp. 11

- 12 ]

. The PIC produce s accurate results , measur ing true gamma radiation exposure rate in μR/hr with an accuracy of ± 5 % [Ref. 20, pp. 3, 5 ; 23 , pp. 1 -2 ]. The EPA

- owned PIC used at the WACC site (serial number 99I089 41 ) had been calibrated by an accredited instrument calibration laboratory i n April 2012 [Ref. 20, pp. 4, 34

- 41]

. T he PIC was deploy ed at each of 70 measurement locations for a minimum of five minutes to allow the instrument response to stabilize; d ata were collected at one

- second intervals and stored in the instrument’s internal memory for subsequent downloading and review by a Certified Health Physicist (CHP) [Ref. 20, p. 5]

. EPA read the concurrent gamma count rates directly from the scintillation detector and recorded the readings on field data sheets [Ref. 19, pp. 13

- 22]

. T he CHP interpret ed the one

- second PIC data and calculated a one - minute average of the gamma radiation exposure rate at each location [Ref. 20, p. 5]

. From th e set of seven possible background locations, the CHP interpreted the measurement at location WAC

- BKG

04, located along Cooper Avenue at the northwest end of the former rail spur, to have some possible impact from the site [Ref. 20, pp. 6, 16, 20]. The CHP selected the six other data points (all collected further from Source 1) as being representative of the true, non

- impacted gamma radiation exposure rate , and calculated the mean site

- specific background gamma radiation exposure rate to be 9.1 μR/hr [Ref. 19, p. 13; 20, p. 6]

. The source area is delineated by gamma radiation exposure rates that equal or exceed two times the site

- specific background gamma r adiation exposure rate (i.e., 18.2 μR/hr ), as shown in Figure 6 [Ref. 19, pp. 5

- 22; 20, pp. 3

- 7, 20, 24

- 31]. This delineated extent of the source area has a close correlation to the area of contamination delineated by previous soil sample analytical results (see Figure s 3 and 6)

. The gamma radiation exposure rates for measurement locations within the source area are presented below in Table 2 [Ref. 19, pp. 13

- 22; 20, pp. 30

- 31]. Locations that did not equal or exceed two times the site

- specific background gamma radiation exposure rate are considered to be outside the boundary of the source.21 SD

- Characterization and Containment Source No.: 1

TABLE 2. GAMMA RADIATION EXPOSURE RATES

– SOURCE 1

Location ID Date Time 1

- Min Interval for PIC Measurement Gamma Radiation Exp os ure Rate Reference s PIC (μR/hr) * Scintillator (cpm)
WAC

- IRV

- 01 9/19/2012 16:27

- 16:32 16:30 18.5 19,794 Ref. 19, pp. 13

- 22 , 36

- 51 ; 20, pp. 5- 7, 24

- 31 ; Figures 5 and 6 of this HRS doc. record WAC

- IRV

- 02 9/19/2012 16:05

- 16:26 16:15 49.5 65,943 WAC

- IRV

- 03 9/19/2012 16:32

- 16:38 16:36 33.7 40,336 WAC

- IRV

- 04 9/19/2012 16:39

- 16:45 16:43 25.0 27,228 WAC

- IRV

- 05 9/19/2012 16:45

- 16:50 16:48 19.1 22,360 WAC

- IRV

- 10 9/19/20 12 18:21

- 18:27 18:25 2,166.3 437,849 WAC

- SPUR

- 01 9/20/2012 9:20

- 9:27 9:24 114.5 145,524 WAC

- PER

- 02 9/20/2012 9:38

- 9:44 9:41 21.8 25,615 WAC

- PER

- 04 9/20/2012 9:51

- 9:56 9:53 18.3 24,289 WAC

- PER

- 06 9/20/2012 10:03

- 10:08 10:06 26.7 36,965 WAC

- PER

- 08 9/20/2012 10:16

- 10:25 10:21 20.3 22,012 WAC

- PER

- 09 9/20/2012 10:30

- 10:56 10:40 19.8 22,625 WAC

- PER

- 11 9/20/2012 11:07

- 11:13 11:11 19.2 21,622 WAC

- PER

- 12 9/20/2012 11:15

- 11:20 11:18 19.8 23,450 WAC

- SPUR

- 02 9/20/2012 11:35

- 11:48 11:43 119.9 147,135 WAC

- PER

- 14 9/21/2012 9:25

- 9:32 9:27 18.9 22,090 WAC

- PER

- 15 9/21/2012 9:33

- 9:39 9:36 33.4 46,397 WAC

- PER

- 17 9/21/2012 9:53

- 10:01 9:56 22.9 26,291 WAC

- PER

- 18 9/21/2012 10:01

- 10:06 10:04 25.9 33,171 WAC

- IRV

- 23 9/20/2012 13:38

- 13:50 13:42 19.8 22,989 WAC

- IRV

- 25 9/20/2012 14:15

- 14:21 14:18 23.9 39,322 WAC

- IRV

- 30 9/20/2012 14:55

- 15:00 14:57 22.5 27,293 WAC

- IRV

- 31 9/20/2012 15:00

- 15:05 15:03 28.4 38,382 WAC

- IRV

- 34 9/20/2012 15:18

- 15:23 15:21 24.2 36,966 μR/hr = M icroroentgens per hour cpm = Counts per minute * The PIC measures gamma radiation within the range of 0 to 10 Roentgens per hour (R/hr) and the zero reading is accurate within ± 0.5 μR/hr [Ref. 23, p. 2]. Therefore, the detection limit of the instrument as used in the field for each measurement is 0.5 μR/hr [Ref. 1, Section 1.1].22 SD

- Characterization and Containment Source No.: 1

Location of the source, with reference to a map of the site:
Soil cont aminated with r esidual waste materials are present beneath most of the subject property building footprints , beneath sidewalks and asphalt surfaces of Irving Avenue and Moffat Street, and at the ground surface throughout the rail spur [Ref. 5 , pp. 38

- 47; 2 0, pp. 4

- 7, 20 ] . The perimeter of Source 1 is shown in Figure 6

.

Containment Release via air pathway: HRS requires separate evaluation of gas and particulate containment for each source at the site. Gas containment is evaluated for sources that contain gaseous hazardous substances (vapor pressure ≥ 10 -9 Torr) and particulate containment is evaluated for sources that contain particulate hazardous substances (vapor pressure ≤ 10 -1 Torr) [Ref. 1, Section 6.1.2 ]. Source 1 contains thorium

- 232 and by nature all of its radioactive progeny, including thoron, in secular equilibrium [Ref. 22, pp. 1, 4]. Thoron, be ing an isotope of the radioactive element radon, has a vapor pressure of 760 Torr [Ref. 2, pp. 20

- 21, 24]. Thorium

- 232 is a particulate hazardous substance [Ref. 2, pp. 9, 13]. Therefore, Source 1 contains both gaseous and particulate hazardous substances and is evaluated for gas containment using HRS Table 6

- 3 and particulate containment using HRS Table 6

- 9. The results of the NYCDDC investigation show that the contaminated soil at the source is at depths within 1 foot of the ground surface in the former rail spur , where there are some exposed soil areas [Ref. 5, pp. 8, 41

- 47] . This situation is listed in HRS Tables 6

- 3 and 6

- 9 as “Uncontaminated soil cover < 1 foot: Other.” B ased on the containment descriptions, Source 1 is assigned a gas containment factor value of 10 and a particulate containment factor value of 10 in the air migration pathway [Ref. 1, Section 6.1.2, Tables 6

- 3 and 6 -9 ].23 SD

- Hazardous Substances Source No.: 1

2.4.1 Hazardous Substances
Residual w aste materials containing thorium were abandoned at the subject property , and th e results of the NYCDDC investigation showed that Source 1 contains elevated levels of t horium

- 232 (see Section 2.2, Table 1 of this HRS documentation record)

. The radioactive decay series for thorium

- 232 includes several radionuclides , including thoron, that are approximately in a state of secular equilibrium (i.e. , the activities of all radionuclides within the series are nearly equal ) [Ref. 22, p. 1] . Therefore, all are considered to be present within the source material

. The decay series for Thorium

- 232 proceeds as follows (with half

- lives in parentheses) [Ref. 22, pp. 1, 4]

• Thorium

- 232 (14 billion years)

• Radium

- 228 (5.8 years)

• A ctinium

- 228 (6.1 hours)

• T horium

- 228 (1.9 years)

• R adium

- 224 (3.7 days)

• R adon

- 220 aka Thoron (56 seconds)

• P olonium

- 216 (0.15 second)

• L ead

- 212 (11 hours)

• B ismuth

- 212 (61 minutes)

• P olonium

- 212 (310 nanoseconds) and T hallium

- 208 (3.1 minutes)

• L ead

- 208 ( stable ). One of the key components of the thorium

- 232 decay series is thoron, which emanates from surfaces where thorium

232 is present [Ref. 18, p. 1]. A hazard associated with airborne thoron comes from its radioactive decay products, a large fraction of which remain suspended in the air, where they can be inhaled and de posited in the lung s ; t he primary health hazard is lung cancer due to alpha particle radiations from these decay products after they have been deposit ed on the bronchial epithelium of the lung [Ref. 18, p. 3]

.24 SD

- Hazardous Waste Quantity Source No.: 1

7.2.5 Hazardous Waste Quantity Source 1 contains radioactive substances and, therefore, it is evaluated for r adionuclide c onstituent q uantity (Tier A) and r adionuclide w astestream q uantity (Tier B) in accordance with HRS Section 7.2.5 and its subsecti ons.

7.2.5.1.1 Radionuclide Constituent Quantity (Tier A)
T he historical documentation and sampling data are insufficient to determine with confidence either the act ivity concentration above background for the radionuclides in Source 1 or the volume of the source itself. T herefore, t he net activity content in the source cannot be estimated in curies or converted to equivalent pounds of nonradioactive hazardous substances [Ref. 1, Section 7.2.5.1.1]. Source 1 is known to contain radioac tive substances with activity concentrations above background [Ref. 5, pp. 45

- 47; 20, pp. 4

- 10, 30

- 33] , so radionuclide constituent qu antity ( Tier A) is assigned a value of unknown but greater than 0 equivalent pounds

. Radionuclide Constituent Quantity (Tier A) Assigned Value: unknown but >0 Since the radionuclide constituent quantity is not adequately determined, radionuclide wastestream quantity (Tier B) is evaluated [Ref. 1, Section 7.2.5.1.1].

7.2.5. 1 .2 Radionuclide Wastestream Quantity (Tier B) Although Source 1 is known to contain radioactive substances, the historical documentation and sampling data are insufficient to estimate the total volume of wastestreams containing radionuclides allocated to the source. T herefore, t he activity content of radionuclide wastestreams allocated to the source expressed in terms of equivalent pounds of nonradioactive hazardous substances, and radionuclide wastestream qu antity ( Tier B) is assigned a value of unknown but greater than 0 equivalen t pounds [Ref. 1, Section 7.2.5.1.2]

. Radionuclide Wastestream Quantity (Tier B) Assigned Value: unknown but >0

7.2.5.1. 3 Source Hazardous Waste Quantity Value for Radionuclides The source hazardous waste quantity value for Source 1 is unknown but >0 for radionuclide w astestream q uantity (Tier B) [Ref. 1, Section 7.2.5.1.3 ]. Source Hazardous Waste Quantity Value: unknown but >025 SD

- Summary

SITE SUMMARY OF SOURCE DESCRIPTIONS

TABLE 3
. HAZARDOUS WASTE QUANTITY AND CONTAINMENT Source Number Source Hazardous Waste Quantity Value Containment Ground Water Surface Water Air Gas Particulate 1 >0 NS NS 10 10
NS = Not Scored

Other Possible Sources
Moffat Street: During t he 2009

- 2010 NYCDDC investigation , g amma radiation level s above the background range ( 6- 10 μR /hr) were recorded along Moffat Street south of the former WACC facility [Ref. 5, pp. 34

- 35]. Based on the se surface gamma readings, the impact to Moffat Street appear ed to extend as much as 300 feet fro m Irving Avenue [Ref. 5, pp . 34

- 35 ]. During the September 2012 investigation, EPA identified an area along the same portion of Moffat Street where gamma radiation exposure rates equal or exceed two times the site

- specific background gamma radiation exposu re rate as summarized in Table 4 [Ref. 19, pp. 5- 16, 22; 20, pp. 4- 7, 20, 30

- 31 ]. As shown in Figure 6 , t he area is separated from Source 1 by measurement locations that did not exceed two times the site

specific background gamma radiation exposure rate [ Ref. 20, pp. 20, 30

- 31]

. TABLE 4. GAMMA RADIATION EXPOSURE RATES

– MOFFAT STREET

Location ID Date Time 1

- Min Interval for PIC Measurement Gamma Radiation Exp os ure Rate Reference s PIC (μR/hr) * Scintillator (cpm)
WAC

- MOF

- 02 9/19/2012 17:21

- 17:26 17:24 30.9 35,783 Ref. 19, pp. 13

- 22 , 36

- 51 ; 20, pp. 5- 7, 24

- 31 ; Figures 5 and 6 of this HRS doc. record WAC

- MOF

- 03 9/19/2012 17:26

- 17:32 17:29 23.8 25,565 WAC

- MOF

- 04 9/19/2012 17:32

- 17:37 17:35 28.3 33,719 WAC

- MOF

- 05 9/19/2012 17:37

- 17:42 17:40 22.3 26,435 WAC

- MOF

- 06 9/19/2012 17:42

- 17:47 17:45 42.2 49,775 WAC

- MOF

- 07 9/19/2012 17:48

- 17:55 17:52 29.8 38,888 WAC

- MOF

- 08 9/19/2012 17:55

- 18:00 17:57 19.0 19,855 WAC

- MOF

- 13 9/21/2012 11:45

- 11:50 11:48 19.0 24,764 μR/hr = M icroroentgens per hour cpm = Counts per minute * The PIC measures gamma radiation within the range of 0 to 10 R/hr and the zero reading is accurate within ± 0.5 μR/hr [Ref. 23, p. 2]. Therefore, the detection limit of the instrument as used in the field for each measurement is 0.5 μR/hr [Ref. 1, Section 1.1].
Sewer disposal: WACC disposed of its thorium

- rich process liquors in the sewer until 1947, when the AEC ordered WACC to halt sewer disposal of thorium waste [Ref. 6, p. 8; 7, p. 5 ]

. I nvestigations conducted in 2007 and 2009 suggest that residual contamination still exists in the sewer lines downstream of the facility [Ref. 5, pp. 30

- 34, 45]

.26 Air

- Observed Release

6.1 LIKELIHOOD OF RELEASE
6.1.1 Observed Release
Real

- time t horon gas concentration measurements collected by EPA in September 2012 form the basis for observed release. At selected locations in background areas, above the source material, and o utside the source area, thoron (radon

- 220) gas concentration measurements in pCi/L were collected with RAD7 Radon Detectors [Ref. 19, pp. 5

- 12, 23

- 29] . Thoron is a radioactive gas that is part of the decay chain for the thorium

- 232 in the waste material at the WACC subject property ; the half

- life of thoron is 56 seconds [Ref. 22, pp. 1, 4] . Each thoron measurement location coincided with a gamma radiation exposure rate measurement location to identify its relative location with respect to the source boundary , as shown in Figure s 4 and 7

. Based on the results of the investigation , the thoron concentrations indicate that this hazardous gas is emanating from Source 1 and entering the ambient air above and o utside the delineated source area.
Direct Observation Observed release by direct observation is not scored

. Chemical Analysis
EPA rented two RAD7 Radon Detectors, serial numbers 2813 and 3076, from the instrument manufacturer, Durridge Company, Inc

. , for use at the WACC subject property [Ref. 20, p. 8 ; 24, pp. 1, 8 ]

. The instruments were pre
- calibrated for thoron by th e manufacturer, as shown on the calibration certificates [Ref. 20, pp. 8, 43

- 46 ; 25, p. 4; 26, pp. 1 -7]. EPA used the RAD7 meters to collect thoron concentration measurements at 15 selected locations in background areas, above the source material, and o ut side the source area [Ref. 19, pp. 5

- 12; 20, p. 16 ] . Based on the manufacturer’s recommendation, E PA used a shortened tube length (1’) and small drying tubes to capture maximum thoron readings, and the pump was running continuously in SNIFF mode [Ref. 19, pp. 5

- 12; 20, pp. 8

- 9] . The measurements were collected at heights of 1 .5 to 6 inches above the ground surface, except that WAC

- SPUR

- 02

- ELEV was collected at a height of 38 inches above the ground surface within the source area [Ref. 19, pp. 23

- 26; 20, p p. 8

- 9]

. For each location, the field team operated the RAD7 meter for a 15

- minute test purge followed by a 1

- hour test [Ref. 19, pp. 23

- 26; 20, pp. 8

- 9] . Upon completion of each test, the thoron results were printed directly from the RAD7 meter [Ref. 19, pp. 27

- 29; 20, p. 9] . Each printout included results for thoron in pCi/L, as well as date/time, temperature (°C), relative humidity (%), and battery voltage [Ref. 19, pp. 27

- 29; 20, p. 9] . Duplicate measurements were collected at locations WAC

- BKG

- 05 and WAC

- SPUR

- 02, where both meters were deployed simultaneously [Ref. 19, pp. 6- 8, 23

- 24]

. The thoron concentrations for each measurement location are presented in Tables 5 and 6 below, and the thoron concentration measurements are also shown in F igure 7

. Each thoron measurement included a standard deviation value calculated and reported by the RAD7 meters, reflecting the two

- sigma level of uncertainty associated with the reported concentration [Ref. 19, pp. 27

- 29; 20, p. 33; 25, p. 4 ]. These res ult

- specific uncertainty levels are considered in evaluating background and contaminated sample concentrations [Ref. 25, pp. 1

- 3]. The background and contaminated samples are considered to be similar and therefore comparable for observed release determina tion

. The background and contaminated samples were all collected during the same time period, September 19

- 21, 2012 (in some cases, concurrently); at similar physical locations ( above exposed soil areas) ; and under similar weather conditions (clear with l ight [< 5 miles per hour], variable winds) [Ref. 19, pp. 6

- 12, 23

- 29 ; 20, pp. 8 -9 ]. Based on gamma readings and position with respect to the source (the extent of which is known), the CHP interpreted the background sample locations (WAC

- BKG

- 01, WAC

- BKG

- 05, and WAC

- BKG

- 06) as representative of true, non

- impacted locations [Ref. 20, p p . 6, 9 ]. Duplicate measurements were collected at location WAC

- BKG

05, where both RAD7 meters were deployed simultaneously [Ref. 19, pp. 6, 23

- 24]. The sample locat ions are shown in Figure 7

.27 Air

- Observed Release

Background Concentrations

TABLE 5. BACKGROUND CONCENTRATIONS Sample ID Date Time Height Hazardous Substance Conc entration (pCi/L) Uncertainty (pCi/L) Projected Max imum (pCi/L) L ower Limit of Detection ( pCi/L) Location
WAC

- BKG

- 01 9/19/12 1515 6 in. Thoron 0.00 0.56 0.56 0.4 60’ west of Source 1 WAC

- BKG

- 05 9/19/12 1641 6 in. Thoron 0.00 0.66 0.66 0.4 180’ NE of Source 1 WAC

- BKG

- 05 9/19/12 1641 6 in. Thoron 0.00 0.56 0.56 0.4 WAC

- BKG

- 06 9/21/12 0954 2 in. Thoron 0.17 0.80 0.97 0.4 85’ west of Source 1 pCi/L = Picocuries per liter NE = Northeast [Ref. 19, pp. 12, 23

- 29 , 52

- 54 , 58 ; 20, pp. 8

- 9; 25, pp. 1, 3 -4 ; Figure 7 of this HRS documentation record]

Based on the se f our projected maximum background concentrations with consideration of the level of uncertainty (WAC

- BKG

- 01, duplicate readings at WAC

BKG

- 05, and WAC

- BKG

- 06) , the mean site

- specific background concentration is calculated as follows [Ref. 25, pp. 1, 3] : Mean site

- specific background ( x ) = (0.56 + 0.66 + 0.56 + 0.97)/4 pCi/L = 0.69 pCi/L28 Air

- Observed Release

Contaminated Samples For radionuclides that occur naturally such as thoron, observed release is established when a measured concentrati on in units of activity (such as pCi/L) are at a level that equals or exceeds a value two standard deviations above the mean site

- specific background concentration for that radionuclide in that type of sample [Ref. 1, Section 7.1.1 ] . The equation for standard deviation ( s ) of the sample set is as follows [Ref. 25, p. 2] :

s = 2 

### )(*) 1 1 ( 

# ∑

−

− xx n i

wh ere n = number of background measuremen ts ( 4) x i = each measured background concentration x = mean site

- specific background concentration (0. 69 pCi/L)
Based on the projected maximum background concentrations and the calculated mean site

- specific background concentration of 0.69 pCi/L, the standard deviation ( s ) of the background sample set is calculated below [Ref. 25, p. 2] :

s = 

### ])69.097.0()69.056.0()69.066.0()69.056.0[(*) 14

1 ( 2 2 2 2 

### −+−+−+−

−

s = 0.19 pCi/L Based on the calculation, t he standard deviation ( s ) of the site

- specific background thoron concentration measurements is 0.1 9 pCi/L, and two times the standard deviation is 0. 38 pCi/L [Ref. 25, p. 2]

. As stated above, concentrations that equal or exceed a value two standard deviations above the mean site

- specific background concentration establish the observed release. Therefore, for the WACC site, concentrations that equal or exceed 1.07 pCi/L (i.e., 0.69 pCi/L + 0.38 pCi/L) establish the observed release [Ref. 1, Section 7.1.1 ; 25, pp. 2 -3]. A s shown in Table 6 below , nine samples from seven locations meet this criterion for observed release [Ref. 25, p. 3]

. Duplicate samples WAC

- SPUR

- 02 and WAC

- SPUR

- 02

- A wer e collected simultaneously at location WAC

- SPUR

02 with two RAD7 meter s, and WAC

- SPUR

- 02

- ELEV was collected from a 38

- inch height at the same location [Ref. 19, p. 24].29 Air

- Observed Release

Contaminated Samples (continued)

TABLE 6. CONTAMINATED SAMPLES Sample ID Date Time Height Hazardous Substance Conc entration (pCi/L) Uncertainty (pCi/L) Projected M in imum (pCi/L) L ower Limit of Detection ( pCi/L) Location
WAC

- SPUR

- 01 9/20/12 1015 1.5 in. Thoron 61.8 6.19 55.61 0.4 On source WAC

- SPUR

- 02 9/20/12 1209 2 in. Thoron 366 16.1 349.9 0.4 On source WAC

- SPUR

- 02A 9/20/12 1209 2 in. Thoron 301 13.5 287.5 0.4 On source WAC

- SPUR

- 02

- ELEV 9/20/12 1344 38 in. Thoron 6.19 2.17 4.02 0.4 On source WAC

- PER

- 01 9/2 0 /12 1 343 2 in. Thoron 2.98 1.77 1.21 0.4 5’ east of S ource 1 WAC

- PER

- 05 9/2 0 /12 1 518 2 in. Thoron 3.94 1.80 2.14 0.4 5’ east of S ource 1 WAC

- PER

- 13 9/21/12 1259 1.5 in. Thoron 3.80 1.77 2.03 0.4 20’ south of S ource 1 WAC

- PER

- 16 9/21/12 1126 2 in. Thoron 10.3 2.71 7.59 0.4 5’ south of S ource 1 WAC

- PER

- 18 9/21/12 1129 2 in. Thoron 8.61 2.74 5.87 0.4 On source pCi/L = Picocuries per liter [Ref. 19, pp. 23

- 29; 20, pp. 8

- 9; 25, pp. 1, 3

- 4; Figure 7 of this HRS documentation record]30 Air

- Observed Release

Level I Samples
There are no benchmarks for thoron ; t herefore, there are no Level I samples [Ref. 1, Section 2.5 ; 2, pp. 20

- 21, 24 ].
Hazardous Substances Released: Thoron ( a.k.a. Radon

- 220)
Attribution During its operation, WACC processed monazite sand s at th e subject property [Ref. 5, pp. 142, 153

- 154; 7, pp. 4

- 5 ]

. Monazite contains approximately 6

- 8% thorium , and residues at the WACC facility property were e nriched to about 30% thorium [Ref. 5, p p . 142 , 153

- 154 ]

. The NYCDDC investigation showed that Source 1 contains these abandoned radioactive residues , including elevated levels of thorium

- 232 [Ref. 5, pp. 41

- 47, 81

- 84]. The radioactive decay of thorium

- 232, which has a half

- life of 14 billion years, proceeds as follows (radioactive half

lives in parentheses): radium

- 228 (5.8 years), actinium

- 228 (6.1 hours), thorium

- 228 (1.9 years), radium

- 224 (3.7 days), radon

- 220 (56 seconds), polonium

- 216 (0.15 second), lead

- 212 (11 hours), bismuth

- 212 (61 minutes), polonium

- 2 12 (310 nanoseconds) and thallium

- 208 (3.1 minutes), and lead

- 208 (stable) [Ref. 22, pp. 1, 4]. Due to the length of time since processing of the monazite sands (about 60 years or more), it is reasonable to assume secular equilibrium (i.e., the activities of all radionuclides within the series are nearly equal) for these radionuclides in Source 1 [Ref. 22, p. 1]. The radioactive gas thoron is solely produced from the thorium

- 232 decay series , and it emanates from surfaces where thorium

- 232 is present [Ref . 18, p. 1; 22, pp. 1, 4]. One of the hazards associated with airborne thoron comes from its radioactive decay products, a large fraction of which remain suspended in the air where they can be inhaled and deposited in the lungs [Ref. 18, p. 3]. There are no other known sources of thoron in the site vicinity [Ref. 13, pp. 15

- 228]. The results of the NYCDDC investigation show that the contaminated soil at the source is at depths within 1 foot of the ground surface in the former rail spur , where there are exposed soil areas [Ref. 5, pp. 8, 41

- 47] . This situation indicates that Source 1 is not contained for particulate or gaseous releases to the air migration pathway [Ref. 1, Section 6.1.2, Tables 6

- 3 and 6

- 9 ]. Based on these considerations, the radioacti ve substances associated with Source 1 are considered to have caused the significant increase of thoron and the observed release is considered to be attributable to S ource 1

.

================================================================================== Air Observed Release Factor Value: 55031 Air

- Toxicity/Mobility

6.2 WASTE CHARACTERISTICS
6.2.1 Toxicity/Mobility
TABLE 7 . TOXICITY/MOBILITY Hazardous Substance Source Nos. Toxicity Factor Value Gas Mobility Factor Value (1) Particulate Mobility Factor Value ( HRS Figure 6

- 3) (1) Toxicity/Mobility Factor Value ( HRS Table 6

- 13) References

Thorium

- 232 1 10,000 N/A 0.0002 2 Ref. 1, Sec

. 6.2.1 ; 2, p. 1 0 Radium

- 228 1 10,000 N/A 0.0002 2 Ref. 1, Sec. 6.2.1 ; 2, p. 13 A ctinium

- 228 1 (2) N/A 0.0002 (2) Ref. 1, Sec. 6.2.1 ; 2, p. 13 T horium

- 228 1 10,000 N/A 0.0002 2 Ref. 1, Sec. 6.2.1 ; 2, p. 13 R adium

- 224 1 (2) N/A 0.0002 (2) Ref. 1, Sec. 6.2.1 ; 2, p. 13 Thoron (R adon

- 220 ) 1, OR (2) 1 N/A (2) Ref. 1, Sec. 6.2.1 ; 2, p. 13; 22, pp. 1, 4 P olonium

- 216 1 (2) N/A 0.0002 (2) Ref. 1, Sec. 6.2.1 ; 2, p. 13 L ead

- 212 1 (2) N/A 0.0002 (2) Ref. 1, Sec. 6.2.1 ; 2, p. 13 B ismuth

- 212 1 (2) N/A 0.0002 (2) Ref. 1, Sec. 6.2.1 ; 2, p. 13 P olonium

- 212 1 (2) N/A 0.0002 (2) Ref. 1, Sec. 6.2.1 ; 2, p. 13 T hallium

- 208 1 (2) N/A 0.0002 (2) Ref. 1, Sec. 6.2.1 ; 2, p. 13 L ead

- 208 ( 3 ) 1 10,000 N/A 0.0002 2 Ref. 1, Sec. 6.2.1 ; 2, p. 1 1
OR = Observed Release N/A = Not applicable (see Note 1 below)
Notes: (1) Mobility factor values are assigned according to the type of hazardous substance (i.e., gaseous, particulate, or gaseous and particulate ) [Ref. 1, Section 6.2.1.2]. A mobility factor value of 1 is assigned to each gaseous hazardous substance that meets criteria for observed release [Ref. 1, Section 6.2.1.2]. (2) Radium

- 228 and thorium

- 228 toxicity factor values listed (which are based on cancer risk estimates for these radionuclides) include the contributions from their short

- lived decay products, assuming equal activity concentrations (i.e., secular equilibrium) with the principal or parent nuclide in the environment. For radium

- 228, the toxicity factor value includes consideration of its decay product actinium

- 228. For thorium

- 228, the toxicity factor value includes consideration of its decay products radium

- 224, radon

- 220, polonium

- 216, lead

- 212, bismuth

212, polonium

- 212, and thallium

- 208 [Ref. 2, p. 13 ; 32 , p p . 1 1, 18

- 19 ]. (3) Lead

- 208 is the final, stable product of the thorium

- 232 decay series [Ref. 22, p. 4] ; therefore, the toxicity and mobility factor values for non

- radioactive lead metal are presented [Ref. 2, p. 1 1].

============== = =================================================================== Toxicity/Mobility Factor Value: 232 Air

- Waste Quantity/Characteristics

6.2.2 Hazardous Waste Quantity

TABLE 8
. HAZARDOUS WASTE QUANTITY Source Number Source Hazardous Waste Quantity Is source hazardous constituent (HWQ) Value ( HRS Section 7.2.5. 1. 3 ) quantity data complete? (yes/no) 1 Unknown but >0 No Sum of Values: 1 (rounded to 1 as specified in HRS Section 7.2.5.2 ) The sum corresponds to a hazardous waste quantity factor value of 1 in HRS Table 2

- 6 [Ref. 1, Section s 2.4.2.2 and 7.2.5.2 ]. As shown previously, t he radionuclide constituent quantity is not adequately determined for Source 1 (see Section 7.2.5.1.1 of thi s HRS documentation record ) and targets for the air migration pathway are subject to Level I I concentrations (see Section 6 .3.2.3 of this HRS documentation record ). The HRS states that i f the radionuclide constituent quantity is not adequately determined for one or more sources and if any target for the migration pathway is subject to Level I or Level II concentrations , then the value from Table 2

- 6 or a value of 100, whichever is greater, is assigned as the hazardous waste quantity factor value for that p athway [Ref. 1, Section 7.2.5.2]. Therefore, a hazardous waste quantity factor value of 100 is assigned for the air migration pathway

.

6.2.3 Waste Characteristics Factor Category Value
Four hazardous substance s (thorium

- 232, radium

- 228 , thorium

- 228, and lead

- 208) correspond to a toxicity/mobility factor value of 2 , as shown previously ( see Section 6.2.1 of this HRS documentation record ). Toxicity/Mobility Factor Value ( 2 ) x Hazardous Hazardous Waste Quantity Factor Value (100): 2 x 10 2

The waste characteristics product of 2 x 10 2 corresponds to a Waste Characteristics Factor Category Value of 3 in HRS Table 2

- 7 [Ref. 1, Section 2.4.3.1 ].

================================================================================== Hazardous Waste Quantity Factor Value: 100 Waste Characteristics Factor Category Value: 333 Air

- Targets
6.3 TARGETS
Th e documented observed release extends 20 feet ( 0.00 34 mile ) south of Source 1 [ Figure 6 ; Ref. 20 , pp. 22, 33 ]

. There are no available benchmarks for thoron ( i.e., radon

- 220) , so there are no Level I targets [Ref. 1, Section 2.5 ; 2, pp. 20

- 21, 24 ]. Therefore, populations within the On

- Source and Greater than 0 to 1⁄4 mile distance categor ies (more than 6,8 00 residents , workers, and students ) are considered as subject to Level II concentrations ( see Section 6.3.2.3 of this HS documentation record )

. The Potential Contamination factor value for populations outside the 1⁄4

- mile radius is not scored because it is not expected to change the overall HRS site score and the listing decision is not significantly affected by this factor [Ref. 21, pp. 2, 5- 148; 154]

. EPA obtained residential populati on data for the target distance limit from the U.S. Census Bureau website , in the form of 2010 Census b lock population data and geographic information system ( GIS ) coverage ; assigned populations to specific distance categories based on the percent of the area of each Census block within each distance category ; and calculated total residential populations for each distance category [Ref. 21, pp. 1

- 2]. Other populations within 1⁄4 mile of the source and considered here include 7 04 students enrolled at the Fran ces E. Carter public school ( K 384) and 7 on

- source workers [Ref. 19, pp. 30

- 33; 21, pp. 1

- 2, 149

- 153]

. W orkers within the Greater than 0 to 1⁄4 mile distance category are not considered for the population factor because the exact number is unknown; the incl usion of these targets is not expected to change the overall HRS site score because the air migration pathway score achieves the maximum value of 100.00 based on the populations already evaluated (see pages 1

- 3 of this HRS documentation record).
Level I Distance Categories Distance categories subject to Level I concentrations: No Level I concentrations (there are no available benchmarks for thoron) Level II Distance Categories Farthest Sample Sample ID: WAC

- PER

- 13 Location: vacant land at south end of former rail spur Reference: Figure 7 ; Ref. 19, pp. 11, 26, 29 ; Ref. 20, pp. 22, 26, 33
Nearest Source: Source 1 ( Waste Tailings ) Distance from the source in miles: 0. 0 034 Reference: Figure 7 Distance categories subject to Level II concentrations:
On -s ource Greater than 0 to 1⁄4 mile Actual Contamination Distance Categories
On

- source Greater than 0 to 1⁄4 mile Potential Contamination Distance Categories
Greater than 1⁄4 to 1⁄2 mile Greater than 1⁄2 to 1 mile Greater than 1 to 2 miles Greater than 2 to 3 miles Greater than 3 to 4 miles34 Air

- Nearest Individual

6.3.1 Nearest Individual Factor
There are no residences or regularly occupied buildings or areas that are subject to Level I concentrations because t here are no available benchmarks for thoron (i.e., radon

- 220) [Ref. 1, Section 2.5; 2, pp. 20

- 21, 24 ]. There are multiple regularly occupied buildings that a re subject to Level II concentrations ( see Section 6.3.2 of this HRS documentation record ) . Therefore, a n earest i ndividual f actor v alue of 45 is assigned [Ref. 1, Sections 2.5 and 6.3.1 ].

Nearest Individual - Level II Concentrations Residence, building or area subject to Level II concentrations:
Due to the observed release to the air migration pathway on the source and 20 feet outside the source boundary at the WACC site, the population s within the On

- source and Greater than 0 to 1⁄4 mile distance categories are considered as subject to Level II concentrations [Ref. 1, Sections 2.5, 6.1.1, and 6.3 ]

. The buildings on Source 1 where the air release has occurred are regularly occupied by workers [Ref. 5, pp. 13

- 19 ; 19, pp. 4 -5 , 30

- 33 ].
Location: 112 7- 11 39 Irving Avenue (on -s ource ) Nearest Source: Source 1 Distance from the nearest source in miles: 0.0 0 References: Figure s 6, 7 ; Ref. 12, p. 2; 19, pp. 13

- 26 , 30

- 33 ; 20, p. 20; 27, pp. 1 -3

======================================= = ========================================== Nearest Individual Factor Value: 4535 Air

- Level I/Level II Populations

6.3.2 Population

6.3.2.2 Level I Concentrations
The Level I c oncentrations f actor v alue is 0 because there are no available benchmarks for thoron (i.e., radon

- 220), so there are no people subject to Level I concentrations [Ref. 1, Section s 6.3.2.2 and 7.3.2 ; 2, pp. 20

- 21, 24 ].

6.3.2.3 Level II Concentrations
Due to t he observed release to the air migration pathway on the source and 20 feet outside the source boundary at the WACC site, and given that there are no available benchmarks for thoron (i.e., radon

- 220), the pop ulation s within the On

- source and Greater than 0 to 1⁄4 mile distance categor ies are considered as subject to Level II concentrations [Ref. 1, Sections 2.5, 6.1.1, and 6.3 ; 20, p. 20 ]

. Based on 2010 Census data for Kings County and Queens County , there are a total of approximately 6,1 59

. 79 residents within 1⁄4 mile of the source ; these populations are considered as subject to Level II concentrations [Ref. 21, pp. 1

- 4, 154 ]

. Other populations considered as subject to Level II concentrations include 7 on

- source workers and 7 04 students enrolled at the Frances E. Carter public school ( K 384) , which is located within 1⁄4 mile of the source on Kings County Tract 409, Block 2002 [Ref. 19, pp. 3- 5, 30

- 33; 21, pp. 1

- 2, 149

- 153 ] . Based on this assessm ent, the total population considered as subject to Level II concentrations within the On

- source and Greater than 0 to 1⁄4 mile distance categor ies is 6,8 70. 79 , which is assigned as the Level II concentrations factor value for the air migration pathway [Ref. 1, Section 6.3.2.3 ].

TABLE 9 . LEVEL II CONCENTRATIONS Distance Category Population Reference(s) On

- source (workers) 7.00 Ref. 19, pp. 30

- 33; 21, pp. 1

- 2 Greater than 0 to 1⁄4 mile (residents) 6,1 59

. 79 Ref. 21, pp. 1

- 2, 4, 154 Greater than 0 to 1⁄4 mile ( students) 7 04 .00 Ref. 21, pp. 1

- 2, 149

- 153 Total Level II 6, 8 7 0

. 79

================================================================================== Population Exposed to Level I Concentrations: 0 Level I Concentrations Factor Value: 0 Level II Concentrations Factor Value: 6,87 0. 7936 Air

- Potential Contamination Population

6.3.2.4 Potential Contamination
The Potential Contamination factor value is not scored because the listing decision is not significantly affected by this factor.

================================================================================== Distance

- weighted Population Subject to Potential Contamination: NS Potential Contamination Factor Value: NS37 Air

- Resources/Sensitive Environments

6.3.3 Resources
The Resources factor value is not scored because the listing decision is not significantly affected by this factor.

6.3.4 Sensitive Environments

The Sensitive Environments factor values are not scored because the listing decision is not significantly affected by those factors.

================================================================================== Resources Factor Value: NS Sensitive Environment Actual Contamination Factor Value: NS Sensitive Environments Potential Contamination Factor Value: NS