HRS DOCUMENTATION RECORD

-- REVIEW COVER SHEET

Name of Site: New Cassel /Hicksville Ground Water Contamination

CERCLIS ID No.: NY0001095363

Date Prepared: March 2 011

Contact Persons

Site Investigations: Guy Bobersky (518) 402

- 9621

New Yor k State Department of Environmental Conservation Albany, NY

Documentation Record: Dennis Munhall (212) 637

- 4343 U.S. Environmental Protection Agency New York, NY

Gerry Gilliland, P.G. (732) 417

- 5826 Weston Solutions, Inc. Edison, NJ

Pathways, Com ponents, or Threats Not Scored

The surface water, soil exposure, and air pathways were not scored because the listing decision is not significantly affected by those pathways. The site score is sufficient to list the site on the ground water pathway scor e.This page has been left blank intentionally.1 HRS DOCUMENTATION RECORD

Name of Site: New Cassel /Hicksville Ground Water Contamination

CERCLIS ID No.: NY0001095363 [Ref. 3, p. 1]

EPA Region: 2 Date Prepared: March 2011

Street Address of Site: * S o uthern end of Iris Place, Westbury, New York 11590 [Ref. 3 , p. 1]

County and State: Nassau County, New York [Ref. 3, p. 1]

General Location in the State: western Long Island [Figure 1 ; Ref. 4, p. 1 ]

Topographic Map: Hicksville, NY [Ref. 4, p. 1]

Latitu de: 40  ̊ 4 5' 08.806 " North (40.752446  ̊ ) Longitude: 73  ̊ 33' 35.212 " West (

- 73.559781  ̊ )

[Ref. 3, p. 1; 4, p. 1; 5, p. 1]

The site consists of a ground water plume with no identified source(s) of contamination. The reference point for the

street address and site la titude/longitude coordinates is Bowling Green Well 1 , one of the wells subject to actual

contamination [Figure 1; Ref. 1, p. 51595; 5, p. 1]. Bowling Green Well 1 does not have a specific street address (i.e., no number), but it is accessible at the south ern end of Iris Place [Figure 1; Ref. 3, p. 1; 10 , p. 59 ].

* The street address, coordinates, and contaminant locations presented in this HRS documentation record identify the general area the site is located. They represent one or more locations EPA con siders to be part of the site based on the screening 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, placed, or otherwise come to be located.” Generally, HRS scoring and the subsequent listing of a release merely represent the initial determin ation 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 ha s come to be located.

Scores

Ground Water Pathway 100.00 Surface Water Pathway Not Scored Soil Exposure Pathway Not Scored Air Pathway Not Scored

HRS SITE SCORE 50.002 WORKSHEET FOR COMPUTING HRS SITE SCORE

New Cassel /Hicksville Gr ound Water Contamination

S S 2

1. Ground Water Migration Pathway Score (S gw ) 100.00 10,000 (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 Wat er 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 ) Not Scored (from Table 6

- 1, line 12)

5. Total of S gw 2 + S

sw 2 + S

s 2 + S

a 2 10,000

6. HRS Site Score Divide the value on line 5 by 4 and take the square root 50.003 GROUND WATER MIGRATION PATHWAY SCORE SHEET

New Cassel/Hicksville Ground Water Contamination

GROUND WATER MIGRATION PATHWAY Factor Categories & Factors MAXIMUM VALUE VALUE ASSIGNED

Likelihood of Release

1. Observed Release 550 550

2. Potential to Release

2a. Containment 10 not sc ored

2b. Net Precipitation 10 not scored

2c. Depth to Aquifer 5 not scored

2d. Travel Time 35 not scored

2e. Potential to Release [lines 2a(2b+2c+2d)] 500 not scored

3. Likelihood of Release 550 550

Waste Characteristics

4. Toxicity/Mobility * 10,000

5. Hazardous Waste Quantity * 10 ,00 0

6. Waste Characteristics 100 100

Targets

7. Nearest Well 50 50

8. Population

8a. Level I Concentrations ** 365

, 740

8b. Level II Concentrations ** 2

, 050

8c. Potential Contamination ** not scored

8d. Population (lines 8a+8b+8c) ** 36 7

, 790

9. Resources 5 not scored

10. Wellhead Protection Area 20 20

11. Targets (lines 7+8d+9+10) ** 367

, 8 6 0

12. Aquifer Score (lines 3x6x12 divided by 82,500) 100 100

13. Ground Water Migration Pathway Sco re (Sgw) 100 100.00

* Maximum value applies to waste characteristics category.

** Maximum value not applicable.REFERENCES

Reference

Number Description of the Reference

1. U.S. Environmental Protection Agency (EPA). Hazard Ranking System, Final Rule . Federal Register, Volume 55, No. 241, pp. 51532-51667. A comple te copy of the HRS is available at http://www.epa.gov/superfund/sites/ npl/hrsres/index.htm#HRS Rule . December 14, 1990. [138 pages]

2. EPA. Superfund Chemical Data Matrix (excerpts) . A complete copy of SCDM is available at http://www.epa.gov/superfund/site s/npl/hrsres/tools/scdm.htm . Excerpts accessed and downloaded September 17, 2010. [19 pages]

3. EPA. Superfund Information Systems, CERCLIS Da tabase, New Cassel/Hicksville GW Contamination:

Site Information and Aliases . Accessed and downloaded from http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0203974 . February 14, 2011. [2 pages]

4. U.S. Department of the Interior Geological Survey (USGS). Hicksville and Freeport Quadrangles, New York, 7.5-Minute Series (Topographic) . 2010. [2 pages]

5. Capriglione, Michele, Weston Solutions, Inc. (WEST ON). Project Note to New Cassel Industrial Area HRS File, Subject: Latitude and Longitude Determination . September 28, 2010. [1 page]

6. Nassau County Department of Health (NCDH), and Dvirka and Bartilucci Consulting Engineers. Investigation of Contaminated Aquifer Segments, Nassau County, NY . June 1986. [65 pages]

7. Lawler, Matusky & Skelly Engineers LLP (LMS). Remedial Investigation/Feasibility Study (RI/FS) Report, New Cassel Industrial Area, Offsite Groundw ater, Town of North Hempstead, Nassau County

. Prepared for New York State Department of Envi ronmental Conservation (NYSDEC). September 2000. [937 pages]

8. NYSDEC Division of Environmental Remediation. Reco rd of Decision, New Cassel Industrial Area Sites, Town of North Hempstead, Nassau County, New Yo rk, Off-site Groundwater South of the New Cassel Industrial Area, Operable Unit No. 3 . October 2003. [105 pages]

9. Dvirka and Bartilucci Consulting Engineers (D&B ). Annual Report, October 2002 through August 2003, Off-Site Groundwater Monitoring and Assessment Pr ogram, New Cassel Industrial Area (Site No. 1-30­ 043), New Cassel, New York . Prepared for NYSDEC. April 2004. [92 pages]

10. Gilliland, Gerry, WESTON. Project Note with attachments to Hicksville Contaminated Ground Water Area site file, Subject: Hicksville Water Distri ct Analytical Results 2002-2008 – Wells 5-2 and 5-3

. October 8, 2010. [252 pages]

11. Nassau County Department of Health (NCDH). Ground Water and Public Supply Well Facts for Nassau County, New York . July 1996. [78 pages]

12. WESTON. Field Logbook with Photo Documentation, New Cassel Industrial Area, Doc. Control No. 996­

4E-AHSW . August 24-25, 2010. [22 pages]

13. WESTON. Field Logbook with Photo Documentation, Hicksville Contaminated Ground Water Area,

Document Control No. 1144-4E-AHSX . August 24-25, 2010. [16 pages]

14. Capriglione, Michele, WESTON. Sampling Trip Report, New Cassel Industrial Area, Document Control

No. 996-2A-AHSZ . September 3, 2010. [16 pages]

4REFERENCES (continued)

Reference

Number Description of the Reference

15. Capriglione, Michele, WESTON. Sampling Trip Re port, Hicksville Contaminated Ground Water Area,

Document Control No. 1144-2A-AHSY . September 3, 2010. [16 pages]

16. EPA Region 2 Laboratory. Approval Form/Project Checklist and Associated File Documents/VOC Data, Project Number: 10080036, Project/Survey Name: New Cassel Industrial . September 22, 2010. [572 pages]

17. EPA Region 2 Laboratory. Approval Form/Project Checklist and Associated File Documents/VOC Data, Project Number: 10080035, Project/Survey Name: Hicksville . September 22, 2010. [472 pages]

18. Gilliland, Gerry, WESTON. Project Note to New Cassel/Hicksville GW Contamination HRS File, Subject: Public Supply Well Information . February 3, 2011. [177 pages]

19. Environmental Data Resources, Inc. (EDR). The EDR Radius MapTM Report with GeoCheck®, Hicksville Water District Plant 5 Wells 5-2 and 5-3, 120 Stewart Ave, Hicksville, NY 11801, Inquiry

Number: 2934649.1s . December 2, 2010. [1327 pages]

20. Henningson, Durham & Richardson Architecture and Engi neering, P.C. (HDR). Pre-Design Investigation Evaluation Report, New Cassel Industr ial Area, Offsite Groundwater OU#3 . Prepared for NYSDEC. March 2010. [421 pages]

21. Busciolano, Ronald, USGS. Statistical Analysis of Long-Term Hydrologic Records for Selection of Drought-Monitoring Sites on Long Island, New York . Scientific Investigations Report 2004-5152. Prepared in cooperation with NYSDEC. 2005. [54 pages]

22. Isbister, John, USGS. Geology and Hydrology of Northeastern Nassau County, New York . Water Supply Paper 1825. Prepared in cooperation with Nassau C ounty Department of Public Works and New York State Water Resources Commission. 1966. [100 pages]

23. EPA Contract Laboratory Program (CLP). Statement of Work for Organics Analysis, Multi-Media, MultiConcentration, SOM01.1; excerpts . May 2005. [70 pages]

24. EPA Region 2 Laboratory. SOP# DW-1, Revision# 2. 1, Analysis of Volatile Organic Compounds in Drinking Water by Purge and Trap GC/MS . February 13, 2009. [28 pages]

25. Agency for Toxic Substances & Disease Registry (ATSDR). ATSDR ToxFAQs, Carbon Tetrachloride, CAS # 56-23-5; 1,1-Dichloroethane, CAS # 75-34- 3; 1,2-Dichloroethane, CAS # 107-06-2; 1,1­ Dichloroethene, CAS # 75-35-4; 1,2-Dichloroethene, CAS # 540-59-0, 156-59-2, and 156-60-5; Chloroethane, CAS # 75-00-3; Tetrachloroethylene, CAS # 127-18-4; 1,1,1-Trichloroethane, CAS # 71-55­ 6; Trichloroethylene, CAS # 79-01-6; and Vinyl chloride, CAS # 75-01-4 . U.S. Department of Health and Human Services. September 1995 to July 2006. [20 pages]

26. Delaware Health and Social Services, Division of Public Health. Frequently Asked Questions:

Trichlorofluoromethane . January 2010. [2 pages]

27. EPA. OPPT Chemical Fact Sheets EPA 749-F-94- 012, Chemicals in the Environment:Freon 113 (CAS No. 76-13-1) and EPA-F-94-012a, Chemical Summary for Freon 113 . Prepared by Office of Pollution Prevention and Toxics. August 1994. [11 pages]

56 REFERENCES (continued)

Reference

Number Description of the Reference

28. EPA. CERCLIS Search Results, Envirofacts, County Name: Nassau , State Abbreviation: NY, Select National Priority List Sites Only NPL ; and Selected NPL Maps . Accessed and downloaded from http://iaspub.epa.gov/enviro/efsystemquery.cerclis?fac_searc h=primary_name&fac_value=&fac_search_ty pe=Beginning+With&postal_code=&location_address=&add_search_type=Beginning+With&city_name= &county_name=Nassau&state_code=NY&NPL=YES&program_search=1&report=1&page_no=1&output _sql_switch=TRUE&database_type=CERCLIS and http://www.epa.gov/superfund/sites/query/queryhtm/nplmapsb.htm# . January 31, 2011. [8 pages]

29. EPA. Quick Reference Fact Sheet EPA 540

- F

- 94

- 028: Using Qualified Data to Docu ment an Observed

Release and Observed Contamination . Office of Emergency and Remedial Response. November 1996. [18 pages]

30. Gilliland, Gerry , W ESTON

. Project Note to New Cassel/Hicksville GW Contamination HRS File, Subject:

Elevations and Thicknesses of Geologic Strata; with attached excerpts from USGS Hydrologic Investigations Atlas HA

- 709: Hydrogeologic Framework of Long Island, New York (Smolensky et al, 1989) . January 28, 2011 . [ 10 page s ]

31. ESC Engineering of New York, P.C. and Stearns and Wheeler, LLC. Vishay General Semiconductor, I nc., Hicksville, New York, Offsite Groundwater Investigation

– Phase V, Summer 2002 . February 7, 2003. [557 pages]

32. Malcolm Pirnie, Inc. (MPI). Groundwater Investigation Report, Former Sylvania Electric Product

Incor porated Facility, Hicksville, New York, Voluntary Cleanup Program, Site No. V

- 00089

- 1 . Prepared for GTE Operations Support Incorporated. March 2003. [203 pages]

33. NYSDEC Division of Water

. New York State Wellhead Protection Program

. September 1990. [ 61 pages]

34. EPA. Region 2 Water

. Wellhead Protection Program

. Accessed and downloaded from http://epa.gov/region02/water/whp.htm

. January 27 , 20 11

. [1 page]SS

– Site Summary

7 SITE SUMMARY

The New Cassel /Hicksville Ground Water Contamination (NCHGWC) site ( EPA ID: NY0001095363) is located in the Towns of Hempstead , North Hempstead, and Oyster Bay , Nassau County, New York [ Figure 1 ; Ref. 3, pp. 1

- 2 ]

. The geographic coordinates of the site are 40  ̊ 45 ' 08

. 80 " north latitude and 73  ̊ 33 ' 35

. 21 " west longitude, based on the

location of the Town of Hempstead

– Bowling Green Well 1 public supply well [Figure 1 ; Ref. 4, p. 1 ; 5, p. 1]. The site

consists of a widespread area of ground water contaminated w ith volatile organic compound s (VOC)

, recognized by Nassau County Department of Health (NCDH) in 1986 [Ref. 6 , pp. 10

- 1 5 , 2 3

- 25, 62 ]

. The plume affects several public supply wells ; f ile documents indicate that Town of Hempstead

– Bowling Green Wells 1 and 2 have shown the presence

of VOCs since a pproximately 19 88 [Ref. 6, p. 12; 7 , p. 56 ; 8, p. 62 ; 9 , pp. 6

- 7, 2 5

- 3 1 ]. Available analytical results for

Hicksville Water District Wells 5

- 2 and 5

- 3 for the period 2002

- 2008 indicate the continuing presence of a similar set of

contaminants (i.e., chlorinated solvents) as the Bowling Green wells [Ref. 1 0 , pp. 1

- 252]. C ontaminants report ed in at

least one well include d carbon tetrachloride ; 1,1

- dichloroethane (DCA) ; 1,2

- DCA ; 1,1

- dichloroethylene (DCE ); cis

- 1,2

- DC E; tetrachloroethylene (PCE); 1,1,1

- trichloroeth a ne (TCA); and trichloroethylene (TCE ) [Ref. 9, pp. 29

- 30; 10, pp. 1

- 6 ]. TCE has been reported as high as 188 micrograms per liter (μg/L) and PCE has been reported up to 46.4 μg/L [Ref. 9, pp. 29

- 30; 10, pp. 1

- 6 ]. As of 1995, NCDH reported that the Bowling Green wells and several Hicksville wells (4

- 2,

5

- 2, 5

- 3, 8

- 1, and 8

- 3) were being treated for VOC removal [Ref. 1 1, pp. 14

- 17].

U.S. Environmental Protection Agency (EPA) collected raw (i.e., pre

- treatme nt) ground water samples from the Bowling Green wells, Hicksville wells, and other nearby public supply wells in August 2010 [Ref. 1 2 , pp. 3

- 22; 13, pp. 3

- 16 ; 14,

pp. 3, 5

- 6, 10

- 16 ; 1 5 , pp. 3, 5, 1 0

- 16 ]

. The analytical results confirmed the presence of ch lorinated solvents at observed release concentrations (i.e., significantly above background) in four Town of Hempstead wells ( Bowling Green 1 and 2,

Roosevelt Field 10 , and Levittown 2A )

, six Hicksville wells ( 4

- 2, 5

- 2, 5

- 3, 8

- 1, 8

- 3, and 9

- 3), and Westbur y Water

District W ell 11 [Figure 1 ; Table 2 ; Ref. 1 6, pp. 29

- 60 ; 1 7 , pp. 29

- 58 ]

. The concentrations of carbon tetrachloride ; 1,1

- DCE; PCE ; and TCE exceed ed the Maximum Contaminant Level s (MCL) in several wells [ Table 2 ; Ref. 2, pp. 11

- 12, 14, 19]

. Sample s collected from upgradient, background wells showed non

- detect ed or low concentrations for all

contaminants of concern [ Figure 1 ; Table 2 ; Ref. 14, pp. 1 0

- 16 ; 1 5 , pp. 10

- 16 ; 16, pp. 29

- 60 ; 17, pp. 29

- 58 ]. The total population associated with the 11 wells showing observed release concentrations is 38,624 persons (4,021 for each Town of Hempstead well; 3,415 for each Hicksville well; and 2,050 for Westbury Well 11) [ Table 2; Ref. 18, pp. 1

- 2].

The NCHGWC site is located in a heavily developed area consisti ng of industrial, commercial, and residential land, where a variety of past industrial and commercial activities could have resulted in the ground water contamination [Ref. 4, pp. 1

- 2; 1 8, pp. 3

- 4, 19

- 27 , 4 0

- 44

, 109

- 118, 124

- 126, 136

- 145, 155

- 159 ; 19, pp. 3

- 34 ]. New York State Department of Environmental Conservation (NYSDEC) has made significant efforts to identify the specific source(s) of ground water

contamination. For instance

, at the New Cassel Industrial Area (NCIA)

, located just north of the Bowli ng Green wells and developed in the 1950s

, NYSDEC investigated 17 facilities to varying degrees from 1994

- 1999 [Ref. 8, pp. 8

- 15]

. Remedial activities have since been conducted by NYSDEC and individual potentially responsible parties (PRP) at s ome facilit ies [Ref. 8, pp. 9

- 18] . Despite the investigative and remedial efforts, NYSDEC has been unable to identify the specific source(s) of contamination in the Bowling Green public supply wells [Ref. 2 0, pp. 4

- 17]

.

The NCHGWC site is underlain by the u pper g lacial a quifer (UGA)

, an unconfined aquifer consisting of Upper Pleistocene, poorly

- sorted sand and gravel deposits

, from ground sur face to a depth of approximately 80 feet below ground surface (ft bgs) [Ref. 8, p. 20 ; 21 , p. 5 ; 22 , pp. 31, 97

- 98 ] . The Ma gothy formation l ying beneath the UGA consists of finer sands, silt, and small amounts of clay (including clay lenses) [Ref. 8, p. 20 ; 21 , p. 5 ] . At the site, there are no other hydrogeologic units located between the UGA and Magothy formation s [Ref. 8, p . 20; 2 0 , p. 5 ] . The Magothy is approximately 5 00

- 580 feet thick at the site, and it is underlain by the Raritan Clay confining unit

, which is

about 1 80

- 200 feet thick at the site [Ref. 2 0, p. 5; 30 , p p

. 1

- 10 ] . The underlying Lloyd Sand aquifer, which is approximately 2 50

- 330 feet thick at the site, sits directly atop bedrock and is the deepest and oldest layer in Long Island’s aquifer system [Ref. 21 , p. 13 ; 22, pp. 23

- 25; 30 , pp. 1

, 7

- 8 ]

. T he Magothy aquifer is the primary source of drinking

water in N assau County , and the Lloyd Aquifer is used to a lesser extent [Ref. 18, pp. 5

- 16; 21

, p p

. 9, 13 ] . Depth of the

water table at the site is 38

- 65 ft bgs, and ground water flows in a south

- southwesterly direction [ Ref. 7, pp. 37, 55, 135; 9, pp. 12, 17; 20, pp. 5, 24, 64

- 65; 21, pp. 7

- 8; 22, pp. 56

- 57, 64, 99 ]

.P:\SAT2\2010_LI_Sites\08883_NCHGWC_Sample_Loc.mxd

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

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### !

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!

!

! !

!

! !

! !

! ! ! ! !

! ! !

<

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<

<

< <

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< <

< < < < <

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### !

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### ! (

NCIA-GW06 Town of Hempstead
Roosevelt Field Well 7 NCIA-GW07 Town of Hempstead
Roosevelt Field Well 10 Site Reference Point
Latitude: 40  ̊ 45' 08.806" Longitude: -73  ̊ 33' 35.212"
NCIA-GW01 Town of Hempstead Bowling Green Well 1

NCIA-GW02 NCIA-GW03 - duplicate Town of Hempstead Bowling Green Well 2

NCIA-GW04 Town of Hempstead
East Meadow Well 5

NCIA-GW05 Town of Hempstead
East Meadow Well 3 NCIA-GW14 Westbury Well 15

NCIA-GW15 Westbury Well 16

NCIA-GW12 Westbury Well 11 NCIA-GW11 Westbury Well 10

NCIA-GW09 Westbury Well 7A NCIA-GW13 Westbury Well 14 NCIA-GW18 Old Westbury Well 5

NCIA-GW17 Old Westbury Well 3

NCIA-GW16 Westbury Well 1

NCIA-GW08 Westbury Well 6 NCIA-GW10 Westbury Well 9

HCGW-GW16 Towm of Hempstead
Levittown Well 2A HCGW-GW05
Hicksville Well 6-1R

HCGW-GW13
Hicksville Well 10-1 HCGW-GW06
Hicksville Well 6-2

HCGW-GW04
Hicksville Well 4-2

HCGW-GW01
Hicksville Well 5-2 HCGW-GW07
Hicksville Well 7-1

HCGW-GW08
Hicksville Well 8-1 HCGW-GW09
Hicksville Well 8-3 HCGW-GW10
Hicksville Well 9-1

HCGW-GW11
Hicksville Well 9-2

HCGW-GW02 HCGW-GW03 - duplicate
Hicksville Well 5-3 HCGW-GW15
Jericho Well 22

HCGW-GW14
Jericho Well 9

HCGW-GW12
Hicksville Well 9-3

Area of Observed Ground
Water Contamination

R Legend


### ! < Public supply well sample location with observed release concentration(s) 

### ! < Background public supply well sample location 

### ! < Sample location of public supply well screened in Lloyd aquifer

Area of Observed Ground Water Contamination 

### ! ( Approximate Center of Observed Contamination 

# ®

Site Area 

### " NJ NY

PA CT

Figure 1 - Site Location Map
New Cassel/Hicksville GW Contamination

Towns of Hempstead and Oyster Bay Nassau County, NY

January 2011 1 EPA New Cassel/Hicksville GW Contamination 1. National Geographic TOPO! U.S. Geologic Survey (USGS). 7-5 Minute

Series (Topographic) Quadrangles: Amityville, NY 1992; Freeport, NY 1994; Hicksville, NY 1992; and Huntington, NY 1992. 2. Weston Solutions, Inc. Region 5 Start-3, Site Logbooks 996-4E-AHSW

(New Cassel Industrial Area) and 1144-4E-AHSX (Hicksville Contaminated Groundwater Area). August 2010. 4,000 0 4,000 2,000

Graphic Scale In Feet9 SD

- Characterization and Containment

Source No.: 1

SOURCE DESCRIPTION

2.2 SOURCE CHARACTERIZATION

Number of the source: 1

Source Type of the source: Other

Name and description of the source: Ground Water Contamination

Source 1 is considered a contaminated ground water plume of unknown volume that cannot be attribute d to any single source [see Section 3.1.1 for a discussion on Attribution]

. The plume currently affects 11 public supply wells : four Town of Hempstead wells (Bowling Green 1 and 2, Roosevelt Field 10, and Levittown 2A), six Hicksville wells (4

- 2, 5

- 2, 5

- 3,

8

- 1, 8

- 3, and 9

- 3), and Westbury Well 11 [Figure 1; Table 2; Ref. 16, pp. 2 9

- 60 ; 17, pp. 29

- 58 ]

.

Historical information and data present evidence of contamination in some wells. F ile documents indicate that Town of Hempstead

– Bowling Green Wells 1 and 2 have shown the presence of VOCs since a pproximately 19 88 [Ref. 6, p. 12; 7, p. 56; 8, p. 62; 9, pp. 6

- 7, 25

- 31 ]. Available analytical results for Hicksville Wells 5

- 2 and 5

- 3 for the period 2002

- 2008 indicate the continuing presence of a similar set of contaminants (i.e., chlorinated solvents) as the Bowling Green

wells [Ref. 1 0, pp. 1

- 252]. C ontaminants report ed in at least one of these well s include d carbon tetrachloride (up to 9 μg/L); 1,1

- DCA (up to 4 μg/L) ; 1,2

- DCA ( up to 0. 9 μg/L ); 1,1

- DCE ( up to 12 μg/L ); cis

- 1,2

- DCE ( up to 6. 6 μg/L ) ; PCE ( up to 46.4 μg/L ); 1,1,1

- TCA ( up to 8 μg/L ); and TCE ( up to 188 μg/L ) [Ref. 9, pp. 29

- 30; 10, pp. 1

- 6]. As of 1995, NCDH reported that the Bowling Green wells and several Hicksville wells (4

- 2, 5

- 2, 5

- 3, 8

- 1, and 8

- 3) were being treated for VOC removal [Ref. 1 1, pp. 14

- 17].

In Augu st 2010, EPA collected raw (i.e., pre

- treatment) ground water samples from 32 public supply wells in the New

Cassel/Hicksville area , including the Bowling Green and Hicksville wells discussed above [Ref. 12, pp. 3

- 22; 13, pp. 3

- 16 ; 14, pp. 3, 5

- 6, 10

- 16 ; 15, pp. 3, 5, 1 0

- 16 ] . The analytical results confirmed the presence of chlorinated solvents at observed release concentrations (i.e., significantly above background) in four Town of Hempstead wells (Bowling Green 1 and 2, Roosevelt Field 10, and Levittown 2A), six Hicksville wells (4

- 2, 5

- 2, 5

- 3, 8

- 1, 8

- 3, and 9

- 3), and Westbury Well 11 [Figure 1; Table s 1

- 2 ; Ref. 16, pp. 29

- 60 ; 17, pp. 29

- 58 ]. The concentrations of carbon tetrachloride; 1,1

- DCE; PCE; and TCE exceeded the MCLs in several wells [ Table 2 ; R ef. 2, pp. 11

- 12, 14, 19]. Samples collected from upgradient, background wells showed non

- detect ed or low concentrations for all contaminants of concern [Figure 1 ; Table 1; Ref. 14, pp. 1 0

- 16 ; 15, pp. 10

- 16 ; 16, pp. 29

- 60 ; 17, pp. 29

- 58 ].

Note: The sourc e is considered to be a single plume because all public supply wells within the mapped area show

elevated concentrations (i.e., observed release) of one or more VOC s [Figure 1; Table 2]. The most prevalent

contaminants are cis

- 1,2

- DCE and TCE at observed release concentrations in nine wells each, followed by PCE and

carbon tetrachloride at observed release concentrations in seven wells and six wells, respectively [Table 2]. Six wells (Bowling Green 1 and 2; and Hicksville Wells 4

- 2, 5

- 2, 5

- 3, and 8

- 3) sho wed observed release concentrations of all four of those contaminants [Table 2]. Other contaminants were detected at observed release concentrations in one or more

wells [ Table 2 ] . In comparison, the same contaminants were either not detected or are pres ent at significantly lower concentrations (i.e., background levels) in 20 public supply wells outside the mapped area to the north, south, east, and
west [ Figure 1; Table 1 ]. There are currently 16 NPL site s in Nassau County [Ref. 2 8 , pp. 1

- 3]. The backg round levels

in Hicksville Wells 9

- 1 and 9

- 2 east of the plume and Roosevelt Field Well 7 on the west indicate separation of the

NCHGWC plume from the nearest NPL sites ( Hooker Chemical/Ruco Polymer Corp to the east

, Pasley Solvents & Chemicals, Inc. to th e west

- southwest , and Old Roosevelt Field Contaminated GW Area to the west) [Ref. 2 8 , pp. 4

- 7 ].10 SD

- Characterization and Containment (continued)

Source No.: 1

Location of the source, with reference to a map of the site:

The ground water plume is iden tified by contamination found in 11 public supply wells. For the purpose of this report, these wells represent a minimum of the plume extent , which exceeds 10 million square feet [Figure 1] . The site is located in western Long Island, New York and is sho wn in Figure 1.

Containment

Release to ground water:

Based on evidence of hazardous substance migration (contamination detected in ground water samples collected from several public supply wells) and due to the fact that there is nothing to prevent the plume from migrating further, a containment factor of 10 is assigned [Ref. 1, p. 51596; 16, pp. 29

- 60 ; 17, pp. 29

- 58 ].11 SD

- Hazardous Substances

Source No.: 1

2.4.1 Hazardous Substances

Historic analytical results from 1988 to 200 8 provide qualitative e vidence of the presence of chlorinated solvents in the Bowling Green W ells 1 and 2 and Hicksville Wells 5

- 2 and 5

- 3. G round water samples collected by EPA in 20 10 confirmed the contamination with data of known and documented quality , as described below. Background sample locations and contaminant levels for comparison to the contaminated samples are discussed in Section 3.1.1.

Historic Sampling Results

– Bowling Green Wells 1 and 2, 1988

- 2003

In an annual ground water monitoring report dated April 2004, NYSDEC presented tables of historic VOC analytical results for samples collected from the Bowling Green wells from 1988 to 2003 [Ref. 9 , pp. 1, 25

- 31]. The report
indicate s that VOCs were present in the wells at least since 1988 and that chlorinated sol vents were present in the wells

from 1999

- 2003 at the following concentration ranges [Ref. 9 , pp. 26

- 30]:

**•** Bowling Green Well 1

o PCE: 3 μg/L to 3 4 μg/L

o TCE: 5 μg/L to 89 μg/L

o 1,2

- DCE: 0.5 μg/L to 3 μg/L

o 1, 1

- DCE: 3 μg/L to 8 μg/L

o 1, 1,1

- TCA : 4 μg/L to 8 μg/L

o 1,1

- DCA: 1 μg/L to 4 μg/L

**•** Bowling Green Well 2

o PCE: 0.5 μg/L to 16 μg/L

o TCE: 11 μg/L to 56 μg/L

o 1,2

- DCE: non

- detect ed to 2 μg/L

o 1, 1

- DCE: non

- detect ed to 3 μg/L

o 1, 1,1

- TCA : non

- detect ed to 3 μg/L

o 1,1

- DCA: non

- detect ed to 1 μg/L

Historic Sampl ing Results

– Hicksville Wells 5

- 2 and 5

- 3, 2002

- 2008

Historic VOC analytical results for raw water samples collected from Hicksville Wells 5

- 2 and 5

- 3 from January 2002 to

November 2008 indicate the continuing presence of chlorinated solvents in both wel ls, at the following concentration ranges [Ref. 10, pp. 1

- 252]:

**•** Hicksville Well 5

- 2

o TCE: 34 μg/L to 188 μg/L

o PCE: 4 μg/L to 3 2.4 μg/L

o Carbon tetrachloride: non

- detect ed to 7 μg/L

o Cis

- 1,2

- DCE: non

- detect ed to 6.6 μg/L

o 1, 1

- DCE: non

- detect ed to 5.5 μg/L

o 1, 1,1

- TCA : non

- detect ed to 4.1 μg/L

o 1,2

- DCA: non

- detect ed to 0.9 μg/L

**•** Hicksville Well 5

- 3

o TCE: 6.2 μg/L to 70.6 μg/L

o PCE: 3.8 μg/L to 46.4 μg/L

o Carbon tetrachloride: non

- detect ed to 9 μg/L

o Cis

- 1,2

- DCE: non

- detect ed to 1.5 μg/L

o 1, 1

- DCE: non

- detect e d to 12 μg/L

o 1, 1,1

- TCA : non

- detect ed to 4.7 μg/L12 SD

- Hazardous Substances (continued)

Source No.: 1

EPA Sampling Event

– Ground Water Samples: August 20 10

In August 2010, EPA collected raw (i.e., pre

- treatment) ground water samples from the Bowling G reen wells , Hicksville wells, and other nearby public supply wells [Ref. 12, pp. 3

- 22; 13, pp. 3

- 16 ; 14, pp. 3, 5

- 6, 10

- 16 ; 15, pp. 3, 5, 1 0

- 16 ]

. The samples were analyzed by the EPA Region 2 Laboratory , not by a Contract Laboratory Program (CLP) laborato ry through the CLP [Ref. 16, pp. 1 5

- 60 ; 17, pp. 1 6

- 58]. The EPA laboratory analyzed the samples for Target Compound List (TCL) trace concentration VOCs according to CLP Statement of Work (SOW) SOM01.1 and internal Standard Operating Procedure (SOP) # DW

- 1 , “Analysis of VOCs in Drinking Water by Purge & Trap GC/MS” [Ref. 16, pp. 15

- 6 0 ; 17, pp. 16

- 58 ; 23, p p . 1

- 70 ; 24 , p p . 1

- 28 ]. The CLP SOW and internal laboratory SOP are both based on EPA

Method 524.2 pu rge

- and

- trap g as c hromatograph/ m ass s pectrometer (GC /MS) techniques [Ref. 23 , p. 21; 24 , p. 3 ].

With few exceptions, t he EPA laboratory was able to achieve reporting limit s (RL) of 0.50 μg/L (e qual to the CLP

Contract

- Required Quantitation Limit s [ CRQL ] ) for all contaminants of concern [Ref. 16, pp. 29

- 68; 17, pp. 29

- 5 8, 93

, 95 ; 23, pp. 9

- 10 ]. The Bowling Green W ell 2 samples (NCIA

- GW02 and NCIA

- GW03) required 20 x dilution s for

q uantitation of PCE and TCE, and the Hicksville Well 5

- 2 sample (HCGW

- GW01) required a 20x dilution for quantitation of TCE, so th os e reporting limits are adjusted accordingly to 10 μg/L (0.50 μg/L x 20 ) [Ref. 1 6 , p p . 2 9, 66, 68, 239

- 240, 251

- 252, 548

- 562; 17, pp. 29, 93, 95, 235

- 236, 449

- 454 ; 24, p. 18 ]. The Hicksville Well 9

- 3 sample (HCGW

- GW12) required a 10x dilution for quantitation of TCE, so that reporting limit is adjusted to 5 μg/L (0.50 μg/L x 10) [Ref. 17, pp. 29, 95, 351

- 352, 4 57

- 463 ; 24, p. 18 ]

. Chain

- of

- custody was maintained for the samples throughout collection, shipping, and analysis [Ref. 14, pp. 12

- 16; 15, pp. 12

- 16; 16, pp. 5

- 26, 571

- 572; 17, pp. 5

- 26, 472].

The EPA analytical results confirmed the presence of VOCs at observed release c oncentrations (i.e., significantly above background) in several well samples, as presented below [Ref. 16, pp. 29

- 60 ; 17, pp. 29

- 58 ]. Samples collected from background wells showed non

- detect ed (ND) or comparatively low concentrations for all contaminants of concern [Ref. 14, pp. 1 0

- 16 ; 15, pp. 10

- 16 ; 16, pp. 29

- 60 ; 17, pp. 29

- 58 ]. Additional information regarding background level s is presented in Section 3.1.1.

Hazardous Substance Sample Number Date Sampled Result (μg/L) R L (μg/L) Reference s

Carbon t etrachloride NCIA

- GW01 0 8 / 24 /20 10 9.6 0.50 1 6, pp. 7, 33, 227

NCIA

- GW02 0 8 / 24 /20 10 1 0 0.50 16, pp. 7, 34, 239

NCIA

- GW0 3 0 8 / 24 /20 10 11 0.50 16, pp. 7, 36, 251

HCGW

- GW01 0 8 / 24 /20 10 2.2 0.50 17, pp. 6, 31, 235

HCGW

- GW02 0 8 / 24 /20 10 5.9 0.50 1 7, pp. 6, 33, 248

HCGW

- GW0 3 0 8 / 24 /20 10 5.9 0.50 1 7, pp. 6, 34, 260

HCGW

- GW0 4 0 8 / 24 /20 10 8.5 0.50 1 7 , pp. 6, 36, 272

HCGW

- GW0 9 0 8 / 24 /20 10 1.8 0.50 1 7, pp. 6, 43, 322

Maximum background * 08/2 4 /2010

08/25/2010 ND 0.50 1 6, pp. 5, 43

- 5 1, 5 8; 17, pp. 5

- 7, 37

- 40, 4 4

- 46, 49

- 50 , 54

- 56

1,1

- DCA HCGW

- GW0 4 0 8 / 24 /20 10 38 0.50 1 7 , pp. 6, 36, 272 Maximum background ( HCGW

- GW14 ) * 08/25/2010 3.8 0.50 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7, 37

- 40, 44

- 46, 49

- 50, 54

- 56

1,2

- DCA HCGW

- GW0 4 0 8 / 24 /20 10 0.86 0.50 1 7 , pp. 6, 36, 272

HCG W

- GW0 9 0 8 / 24 /20 10 1.1 0.50 1 7 , pp. 6, 43, 322

Maximum background* 08/2 4 /2010

08/25/2010 ND 0.50 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7, 37

- 40, 44

- 46, 49

- 50, 54

- 5613 SD

- Hazardous Substances (continued)

Source No.: 1

EPA Sampling Event

– Ground Water Sample s: August 20 10 (continued)

Hazardous Substance Sample Number Date Sampled Result (μg/L) R L (μg/L) Reference

1,1

- DCE NCIA

- GW01 0 8 / 24 /20 10 13 0.50 1 6, pp. 7, 32, 227

NCIA

- GW02 0 8 / 24 /20 10 7.7 0.50 16, pp. 7, 34, 239

NCIA

- GW0 3 0 8 / 24 /20 10 8.0 0.50 16, pp . 7, 35, 251

HCGW

- GW0 4 0 8 / 24 /20 10 29 0.50 1 7 , pp. 6, 35, 272 Maximum background (NCIA

- GW16 ) * 08/25/2010 1.7 0.5 0 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7, 37

- 40, 44

- 46, 49

- 50, 54

- 56

cis

- 1,2

- DCE NCIA

- GW01 0 8 / 24 /20 10 2.2 0.50 1 6, pp. 7, 32, 227

NCIA

- GW02 0 8 / 24 /20 10 6.6 0.50 16, pp. 7, 34, 239

NCIA

- GW0 3 0 8 / 24 /20 10 6.7 0.50 16, pp. 7, 36, 251

NCIA

- GW 12 0 8 / 25 /20 10 0.59 0.50 16, pp. 6, 59, 384

HCGW

- GW01 0 8 / 24 /20 10 3.9 0.50 17, pp. 6, 31, 235

HCGW

- GW0 2 0 8 / 24 /20 10 1.1 0.50 1 7, pp. 6, 3 2 , 248

HCGW

- GW0 3 0 8 / 24 /20 10 1.1 0.50 1 7, pp. 6, 34, 260

HCGW

- GW0 4 0 8 / 24 /20 10 23 0.50 1 7 , pp. 6, 36, 272

HCGW

- GW0 9 0 8 / 24 /20 10 1.7 0.50 1 7, pp. 6, 43, 322

HCGW

- GW 1 2 0 8 / 24 /20 10 0.73 0.50 1 7, pp. 7, 48, 351

HCGW

- GW 16 0 8 / 24 /20 10 3.0 0.50 1 7, pp. 7, 51, 371

Maximum backgr ound* 08/2 4 /2010

08/25/2010 ND 0.50 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7, 37

- 40, 44

- 46, 49

- 50, 54

- 56
Chloroethane (a.k.a. Ethyl chloride [Ref. 2, p. 17]) HCGW

- GW0 4 0 8 / 24 /20 10 1.1 0.50 1 7 , pp. 6, 3 5 , 272

Maximum background* 08/2 4 /2010

08/25/2010 ND 0.50 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7, 37

- 40, 44

- 46, 49

- 50, 54

- 56

PCE NCIA

- GW01 0 8 / 24 /20 10 26 0.50 1 6, pp. 7, 33, 227

NCIA

- GW02 0 8 / 24 /20 10 13 J ** 10 16, pp. 7, 34, 239, 548 ; 24, p.

18

NCIA

- GW0 3 0 8 / 24 /20 10 69 10 16, pp. 7, 36, 251, 556 ; 24, p.

18

HCGW

- GW01 0 8 / 24 /20 10 19 0.50 17, pp. 6, 31, 235 , 449

HCGW

- GW0 2 0 8 / 24 /20 10 41 0.50 1 7, pp. 6, 33, 248

HCGW

- GW0 3 0 8 / 24 /20 10 40 0.50 1 7, pp. 6, 34, 260

HCGW

- GW0 4 0 8 / 24 /20 10 21 0.50 1 7 , pp. 6, 36, 272

HCGW

- GW0 8 0 8 / 24 /20 10 24 0.50 1 7, pp. 6, 42, 311

HCGW

- GW 09 0 8 / 24 /20 10 16 0.50 1 7, pp. 6, 43, 322 Maximum background ( HCGW

- GW14 ) * 08/25/2010 2.2 0.50 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7, 37

- 40, 44

- 46, 49

- 50, 54

- 56

1,1,1

- TCA NCIA

- GW01 0 8 / 24 /20 10 19 0.50 1 6, pp. 7, 33, 227

HCGW

- GW0 4 0 8 / 24 /20 10 12 0.50 1 7 , pp. 6, 36 , 272
Maximum background (NCIA

- GW16) * 08/25/2010 1.7 0.50 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7, 37

- 40, 44

- 46, 49

- 50, 54

- 5614 SD

- Hazardous Substances (continued)

Source No.: 1

EPA Sampling Event

– Ground Water Samples: August 20 10 (continued)

Hazardous Substance Sample Number Date Sampled Result (μg/L) R L (μg/L) Reference

TCE NCIA

- GW01 0 8 / 24 /20 10 35 0.50 1 6, pp. 7, 33, 227

NCIA

- GW02 0 8 / 24 /20 10 40 J ** 10 16, pp. 7, 34, 239, 548; 24, p.

18

NCIA

- GW0 3 0 8 / 24 /20 10 110 10 16, pp. 7, 36, 251, 556; 24, p.

18

NCIA

- GW0 7 0 8 / 24 /20 10 17 0.50 14, p. 12; 16, p . 9

HCGW

- GW01 0 8 / 24 /20 10 100 10 17, pp. 6, 31, 235 , 449; 24, p.

18

HCGW

- GW0 2 0 8 / 24 /20 10 59 0.50 1 7, pp. 6, 33, 248

HCGW

- GW0 3 0 8 / 24 /20 10 58 0.50 1 7, pp. 6, 34, 260

HCGW

- GW0 4 0 8 / 24 /20 10 44 0.50 1 7 , pp. 6, 36, 272

HCGW

- GW0 9 0 8 / 24 /20 10 24 0.50 1 7, pp. 6, 43, 322

HCGW

- GW 1 2 0 8 / 24 /20 10 56 5 1 7, pp. 7, 48, 351; 24, p. 18

HCGW

- GW 16 0 8 / 24 /20 10 11 0.50 1 7, pp. 7, 51, 371 Maximum background ( HCGW

- GW14 ) * 08/25/2010 2.7 0.50 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7, 37

- 40, 44

- 46, 49

- 50, 54

- 56

Trichlorofluoromethane (a.k.a. Freon 11 [Ref. 2, p. 18]) HCGW

- GW0 4 0 8 / 24 /20 10 0.83 0.50 1 7 , pp. 6, 35, 272

Maximum background * 08/2 4 /2010

08/25/2010 ND 0.50 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7, 37

- 40, 44

- 46, 49

- 50, 54

- 56

1,1 ,2

- Trichloro

- 1,2,2

- trifluoroethane (a.k.a.

CFC

- 113 [Ref. 27, p. 3]) HCGW

- GW01 0 8 / 24 /20 10 0.77 0.50 17, pp. 6, 31, 235

HCGW

- GW0 2 0 8 / 24 /20 10 0.85 0.50 1 7, pp. 6, 3 2 , 248

HCGW

- GW0 3 0 8 / 24 /20 10 0.85 0.50 1 7, pp. 6, 34, 260

HCGW

- GW0 4 0 8 / 24 /20 10 1.2 0.50 1 7 , pp. 6, 3 5 , 272

HCGW

- GW0 8 0 8 / 24 /20 10 0.94 0.50 1 7, pp. 6, 41, 311

HCGW

- GW 09 0 8 / 24 /20 10 4.8 0.50 1 7, pp. 6, 43, 322

HCGW

- GW 12 0 8 / 24 /20 10 7.9 0.50 1 7, pp. 7, 47, 351

Maximum background* 08/2 4 /2010

08/25/2010 ND 0.50 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7 , 37

- 40, 44

- 46, 49

- 50, 54

- 56
Vinyl chloride HCGW

- GW0 4 0 8 / 24 /20 10 0.63 0.50 1 7 , pp. 6, 3 5 , 272

Maximum background* 08/2 4 /2010

08/25/2010 ND 0.50 1 6, pp. 5, 43

- 51, 58; 17, pp. 5

- 7, 37

- 40, 44

- 46, 49

- 50, 54

- 56

*Background samples included NCIA

- GW04, NCIA

- GW05, NCIA

- GW06, NCIA

- GW08, NCIA

- GW09, NCIA

- GW11,

NCIA

- GW13, NCIA

- GW14, NCIA

- GW15, NCIA

- GW16, NCIA

- GW17, NCIA

- GW18

, HCGW

- GW05, HCGW

- GW06,

HCGW

- GW07, HCGW

- GW10, HCGW

- GW11, HCGW

- GW13, HCGW

- GW14, and HCGW

- GW15 [Figure 1 ; Table 1 ].

Several contaminants of con cern (c arbon tetrachloride ; 1,2

- DCA; cis

- 1,2

- DCE ; ethyl chloride; Freon 11 ; CFC

- 113 ; and vinyl chloride) were not detected in any background samples [Ref

. 1 6, pp. 5, 43

- 51, 58, 298

- 347, 376

- 383; 17, pp. 5

- 7,

37

- 40, 44

- 46, 49

- 50, 54

- 56, 286

- 310, 333

- 350, 36 3

- 370, 382

- 400 ].

** The lab used an open vial with headspace for dilution analysis of NCIA

- GW02, so PCE and TCE results (reported from the dilution) are qualified "J" (i.e., t he identification of the analyte is acceptable; the reported value is an estimat e ) and are likely to be biased low [Ref. 16, pp. 29

- 30 , 68, 239, 548]. These results are considered usable because l ow bias

release concentrations are likely to be underestimates of true concentrations ; therefore, i f the reported low bias release

concentr ation is three times above unbiased background levels, these release samples would still meet the HRS criteria (i.e., t he true concentrations would still be three times above the background level ) [Ref. 29 , pp. 5, 8].15 SD

- Hazardous Wa ste Quantity

Source No.: 1

2.4.2 Hazardous Waste Quantity

2.4.2.1.1 Hazardous Constituent Quantity

The information available is not sufficient to evaluate Tier A source hazardous waste quantity; therefore, hazardous constituent quantity is not scored (NS) [Ref. 1, pp. 51590

- 51591].

Hazardous Constituent Quantity (C) Value: NS

2.4.2.1.2 Hazardous Wastestream Quantity

The information available is not sufficient to evaluate Tier B source hazardous waste quantity; therefore, hazardous
wastestream qua ntity is not scored [Ref. 1, p. 51591].

Hazardous Wastestream Quantity (W) Value: NS

2.4.2.1.3 Volume

The extent of the area of observed ground water contamination exceeds 100 million square feet [Figure 1]. Assuming a very conservative average plum e height of 0. 0 1 foot, the minimum volume would be 1 million cubic feet , which is

converted to cubic yards as follows :

1,000,000 ft 3 ÷ 27 ft 3 /yd 3 = 37,037.037 yd 3

The source type is ‘Other,’ so the volume value is divided by 2.5 to obtain the assigned v alue, as shown below [Ref. 1, p.

51591 , Section 2.4.2.1.3, Table 2

- 5 ].

Dimension of source (yd 3 ) : 37,037.037 yd 3
Volume (V) Assigned Value: ( 37,037.037 )/2.5 = 14,814.81 4

2.4.2.1.4 Area

The area of observed ground water contamination exceeds 2, 2 00 a cres [Figure 1]. However, Tier D is not evaluated for source type “other” [Ref. 1, p. 51591, Table 2

- 5 , Section 2.4.2.1.3 ].

Area of source (ft 2 ): N/A Area (A) Assigned Value: 0

2.4.2.1.5 Source Hazardous Waste Quantity Value

The source hazardous w aste quantity value for Source 1 is 14,814.81 4 for Tier C

- Volume [Ref. 1, p. 51591].

Source Hazardous Waste Quantity Value: 14,814.81 416 SD

- Summary

SITE SUMMARY OF SOURCE DESCRIPTIONS

Source Number Source Hazardous Waste Quantity

Value Containmen t

Ground Water Surface

Water Air (Gas) Air (Particulate)

1 14,814.81 4 10 NS NS NS

NS = Not Scored17 GW

- General

3.0 GROUND WATER MIGRATION PATHWAY

3.0.1 General Considerations

The aquifer being evaluated at the NCHGWC site is the Magothy aquifer , which is the primary source of drinking water in Nassau County [ Ref. 18, pp. 5

- 16; 21, p p

. 9, 13 ]

. The public supply wells sampled by EPA in August 2010 all withdraw water from the Magothy aquifer, with one exception: Westbury Well 9 withdraws water fro m the deeper Lloyd Sand aquifer [Ref. 14, pp. 5

- 6; 15, p. 5; 18, pp. 2

- 16 ]. Only the wells that were sampled are considered for scoring, but

t he Magothy aquifer underlies most of Nassau County , including the NHCGWC site and surroundings, and it is the mo st extensive hydrogeologic unit in the region [Ref. 20, p. 5; 21, pp. 5

- 6 ; 30 , pp. 3

- 4 ]. The thickness of the Magothy aquifer ranges from approximately 500

- 580 feet at the site, and it is situated at elevations ranging from approximately 40 feet

above mea n sea level (MSL) to 560 f eet below MSL [Ref. 30, pp. 1

- 10 ]. At the NCHGWC site , the Magothy is overlain by the u pper g lacial a quifer (UGA) from ground sur face to a depth of approximately 60

- 100 ft bgs [Ref. 8, p. 20; 21, p. 5; 22, pp. 97

- 98 ; 30, p. 1 ]

. T here are no other hydrogeologic units located between the UGA and Magothy formation s [Ref. 8, p. 20; 20, p. 5]

. Depth to the water table at the site is 38

- 65 ft bgs, and ground water flows in a south

- southwesterly

direction [Ref. 7, pp. 37, 55, 135; 9, p p. 12, 17; 20, pp. 5, 24, 64

- 65 ; 21, pp. 7

- 8; 22, pp. 56

- 57, 64, 99 ]

.

Aquifer/Stratum 1 (shallowest)

Stratum Name : Upper g lacial aquifer (UGA)

Description : T he UGA is an unconfined aquifer consisting of Upper Pleistocene, poorly

- sorted sand and gravel deposits

, from ground sur face to a depth of approximately 60

- 100 ft bgs [Ref. 8, p. 20; 21, p. 5; 22, pp. 31, 97

- 98 ; 30, p. 1 ]

. Depth

to the water table at the site is 38

- 65 ft bgs [Ref. 7, pp. 37, 55, 135; 9, pp. 12, 17; 20, pp. 5, 24, 64

- 65]

. T he UGA is underlain by the Magothy formation [Ref. 8, p. 20; 20, p. 5]

.

Aquifer/Stratum 2

Stratum Name : Magothy aquifer

Description : The Magothy aquifer underlies most of Long Island, including the NHCGWC site and surroundings , and it

is the most extensive h ydrogeologic unit in the region [Ref. 20, p. 5; 21, pp. 5

- 6 ; 30, pp. 1 , 3

- 4 ]. The Magothy consists of finer sands, silt, and small amounts of clay (including clay lenses) [Ref. 8, p. 20; 21, p. 5]

. It is approximately 500

- 580

feet thick at the site , and it is underlain by the Raritan Clay confining unit [Ref. 20, p. 5; 21, pp. 3, 5 ; 30, pp. 1, 6

, 10 ]

.

Aquifer/Stratum 3

Stratum Name : Raritan Clay confining unit

Description : The Raritan Clay confining unit at the base of the Magothy formation consists of gray clay with silt and fine

sand and is about 1 80

- 200 feet thick at the site [Ref. 20, p. 5; 21, pp. 3, 5

- 6 ; 22, pp. 25

- 27 ; 30, pp. 1 , 3

, 6

- 7 ]

. It is underlain by the Lloyd Sand aquifer [Ref. 22, pp. 23

- 27; 30, pp. 1, 7 ].

Aquifer/Stratum 4

Stratum Name : Lloyd Sand aquifer

Description : The Lloyd Sand aquifer , which is approximately 2 50

- 330 feet thick at the site, consists of fine to coarse sand and gravel, commonly in a clayey matrix, with lenses and layers of clay and silt [Ref. 22, p. 19, 23

- 25 ; 3 0, pp. 1, 7

- 8 ]. It sits directly atop bedrock and is the deepest and oldest layer in Long Island’s aquifer system [Ref. 21, p. 9 ; 22, pp.

23

- 25 ]

. The Lloyd Sand aquifer is used for water supply in Nassau County , but to a much lesser extent than the Magoth y aquifer [Ref. 18, pp. 5

- 16; 21, p p

. 9, 13 ; 22, pp. 26

- 35]

.18 GW

- Observed Release

3.1 LIKELIHOOD OF RELEASE

Historic analytical results from 1988 to 2008 provide a preponderance of qualitative evidence of the presence of

chlorinated solvents in the Bowl ing Green Wells 1 and 2 and Hicksville Wells 5

- 2 and 5

- 3 [see Section 2.4.1] . Ground water samples collected by EPA in 2010 confirm the contamination and demonstrate the observed release to ground

water with data of known and documented quality, as descri bed below.

3.1.1 Observed Release

Aquifer Being Evaluated: Magothy aquifer

An observed release is documented for the NC HGWC site. Chemical analyses for ground water samples collected from several wells in August 2010 show the presence of chlorinated s olvents [ Ref. 16, pp. 29

- 68; 17, pp. 29

- 56 ].

Direct Observation

The aquifer is not evaluated for observed release by direct observation.

Chemical Analysis

EPA collected raw (i.e., pre

- treatment) ground water samples from several public supply wells in August 2010 [Ref. 12, pp. 3

- 22; 13, pp. 3

- 16 ; 14, pp. 3, 5

- 6, 10

- 16 ; 15, pp. 3, 5, 1 0

- 16 ]

. The samples were analyzed by the EPA Region 2 Laboratory, not by a CLP laboratory through the CLP [Ref. 16, pp. 15

- 60; 17, pp. 16

- 58]. The EPA laboratory analyzed the samples for TCL trace concentration VOCs according to CLP SOW SOM01.1 and internal SOP # DW

- 1, “Analysis of VOCs in Drinking Water by Purge & Trap GC/MS” [Ref. 16, pp. 15

- 60; 17, pp. 16

- 58; 23, p p . 1

- 70 ; 24, p p . 1

- 28 ].

The CLP SOW and internal laborat ory SOP are both based on EPA Method 524.2 pu rge

- and

- trap GC/MS techniques [Ref. 23, p. 21; 24, p. 3].

With few exceptions, the EPA laboratory was able to achieve RLs of 0.50 μg/L (equal to the CLP CRQLs) for all contaminants of concern [Ref. 16, pp. 29

- 6 8; 17, pp. 29

- 58, 93, 95; 23, pp. 9

- 10]. The Bowling Green Well 2 samples (NCIA

- GW02 and NCIA

- GW03) required 20x dilutions for quantitation of PCE and TCE, and the Hicksville Well 5

- 2 sample (HCGW

- GW01) required a 20x dilution for quantitation of TCE, so those reporting limits are adjusted accordingly to 10 μg/L (0.50 μg/L x 20) [Ref. 16, pp. 29, 66, 68, 239

- 240, 251

- 252, 548

- 562; 17, pp. 29, 93, 95, 235

- 236, 449

- 454 ; 24, p. 18 ]. The Hicksville Well 9

- 3 sample (HCGW

- GW12) required a 10x dilution for quantitation of TCE, so tha t reporting limit is adjusted to 5 μg/L (0.50 μg/L x 10) [Ref. 17, pp. 29, 95, 351

- 352, 457

- 463 ; 24, p. 18 ].

Chain

- of

- custody was maintained for the samples throughout collection, shipping, and analysis [Ref. 14, pp. 12

- 16; 15, pp. 12

- 16; 16, pp. 5

- 26, 57 1

- 572; 17, pp. 5

- 26, 472].

The EPA analytical results confirmed the presence of VOCs at observed release concentrations (i.e., significantly above background) in four Town of Hempstead wells (Bowling Green 1 and 2, Roosevelt Field 10, and Levittown 2A), s ix Hicksville wells (4

- 2, 5

- 2, 5

- 3, 8

- 1, 8

- 3, and 9

- 3), and Westbury Well 11 [Ref. 16, pp. 29

- 60 ; 17, pp. 29

- 58 ]. The concentrations of carbon tetrachloride; 1,1

- DCE; PCE; and TCE exceeded the MCLs in several wells [Ref. 2, pp. 11

- 12, 14, 19]. Samples co llected from background wells showed non

- detect ed (ND) or comparatively low concentrations for all contaminants of concern [Figure 1 ; Ref. 14, pp. 1 0

- 16 ; 15, pp. 10

- 16 ; 16, pp. 29

- 60 ; 17, pp. 29

- 58 ]. Table s 1 and 2
present information and analytical resul ts for the well samples that document background and observed release concentrations, respectively.

Note on J

- qualified results in Table 2: The lab used an open vial with headspace for dilution analysis of NCIA

- GW02, so PCE and TCE results (reported from the dilution) are qualified "J" (i.e., t he identification of the analyte is acceptable; the reported value is an estimate ) and are likely to be biased low [Ref. 16, pp. 29

- 30 , 68, 239, 548]. These results are considered usable because l ow bias

release con centrations are likely to be underestimates of true concentrations ; therefore, i f the reported low bias release concentration is three times above unbiased background levels, these release samples would still meet the HRS criteria (i.e., t he true concentra tions would still be three times above the background level ) [Ref. 29 , pp. 5, 8].19 GW

- Observed Release (continued)

Notes on sample similarity and background conditions: All background and contaminated samples documenting the observed release were collect ed from the aquifer under consideration [Figure 1 ; Ref. 18, pp. 1

- 2 ]. S amples from wells located north, south, east, and west of the area of observed ground water contamination are evaluated as representative background samples because they were collected

from wells screened at similar elevations in the same aquifer [Figure 1 ; 1 8 , pp. 2

- 4] . The background and release samples were collected during the same 2

- day sampling period using the same sampling personnel and procedures [ Ref. 12, pp. 3

- 22; 13, pp. 3

- 16 ; 14, pp. 2

- 6 , 10

- 16 ; 15, pp. 2

- 6 ; 1 0

- 16 ]. Background and release samples were analyzed within the same laboratory batch es under identical, acceptable QA/QC conditions [Ref. 16, pp. 5

- 7, 15

- 16, 29, 62

- 70 , 571

- 572 ; 17, pp. 5

- 7, 16

- 17, 29, 59, 90

- 97 ]. Th e compounds found in the public w ells are not naturally occurring, and the non

detect ed concentrations in some wells show that the compounds are not ubiquitous in the area [Ref. 16, pp. 29

- 60 ; 17, pp.

29

- 58; 25, pp. 1

- 20; 26, p. 1; 27, pp. 1, 3 ].Table 1 -Background Concentrations, page 1 of 4Public Supply Well Sampling - August 2010New Cassel/Hicksville Ground Water Contamination SiteBackground ConcentrationsWell NameEast Meadow 5East Meadow 3Roosevelt Field 7Westbury 6Westbury 7AAquiferMagothyMagothyMagothyMagothyMagothyScreened Interval (ft ±MSL)-420 to -470-439 to -500-375 to -503-170 to -231-220 to -290Sample IDNCIA-GW04NCIA-GW05NCIA-GW06NCIA-GW08NCIA-GW09Sample Date08/24/1008/24/1008/24/1008/25/1008/25/10References12, p. 4; 14, pp. 5, 12;18, pp. 2, 912, p. 4; 14, pp. 5, 12;18, pp. 2, 812, pp. 5-6; 14, pp. 5,12; 18, pp. 2, 1512, p. 11; 14, pp. 5,14; 18, pp. 2, 10, 3012, p. 11; 14, pp. 5,14; 18, pp. 2, 11, 53VOCs (micrograms per liter [μg/L])ResultRLResultRLResultRLResultRLResultRLCarbon tetrachloride0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1-Dichloroethane0.50 U0.501.10.501.70.502.50.502.70.501,2-Dichloroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1-Dichloroethene0.50 U0.500.50 U0.500.500.501.00.500.890.50cis-1,2-Dichloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Chloroethane (a.k.a. Ethyl chloride)0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Tetrachloroethene0.50 U0.501.00.500.50 U0.500.830.500.50 U0.501,1,1-Trichloroethane0.50 U0.500.50 U0.500.50 U0.501.00.500.940.50Trichloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.560.50Trichlorofluoromethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1,2-Trichloro-1,2,2-trifluoroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Vinyl chloride0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50References16, pp. 7, 37, 26316, pp. 7, 38-39, 27116, pp. 7, 40, 28016, pp. 5, 53-54, 34816, pp. 5, 55, 358Abbreviations and Acronyms:ft±MSL - feet above or below mean sea levelRL - Reporting limitData Qualifiers:U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30].Notes:Italicsindicates the maximum background levelTable 1 -Background Concentrations, page 2 of 4Public Supply Well Sampling - August 2010New Cassel/Hicksville Ground Water Contamination SiteBackground Concentrations (continued)Well NameWestbury 10Westbury 14Westbury 15Westbury 16Old Westbury 1AquiferMagothyMagothyMagothyMagothyMagothyScreened Interval (ft ±MSL)-308 to -374-180 to -270-370 to -444-346 to -429-298 to -338Sample IDNCIA-GW11NCIA-GW13NCIA-GW14NCIA-GW15NCIA-GW16Sample Date08/25/1008/25/1008/25/1008/25/1008/25/10References12, p. 10; 14, pp. 5,14; 18, pp. 2, 10, 3612, p. 10; 14, pp. 5,14; 18, pp. 2, 10, 4912, pp. 8-9; 14, pp. 5,14; 18, pp. 2, 15, 5712, pp. 10-11; 14, pp.6, 14; 18, pp. 2, 15, 6112, p. 12; 14, pp. 6,14; 18, pp. 2, 7, 77VOCs (micrograms per liter [μg/L])ResultRLResultRLResultRLResultRLResultRLCarbon tetrachloride0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1-Dichloroethane0.590.501.30.500.50 U0.500.600.500.50 U0.501,2-Dichloroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1-Dichloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.501.70.50cis-1,2-Dichloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Chloroethane (a.k.a. Ethyl chloride)0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Tetrachloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1,1-Trichloroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.501.70.50Trichloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Trichlorofluoromethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1,2-Trichloro-1,2,2-trifluoroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Vinyl chloride0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50References16, pp. 5, 58, 37616, pp. 5, 43, 29816, pp. 5, 44-45, 30616, pp. 5, 46, 31416, pp. 5, 47-48, 322Abbreviations and Acronyms:ft±MSL - feet above or below mean sea levelRL - Reporting limitData Qualifiers:U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30].Notes:Italicsindicates the maximum background levelTable 1 -Background Concentrations, page 3 of 4Public Supply Well Sampling - August 2010New Cassel/Hicksville Ground Water Contamination SiteBackground Concentrations (continued)Well NameOld Westbury 3Old Westbury 5Hicksville 6-1RHicksville 6-2Hicksville 7-1AquiferMagothyMagothyMagothyMagothyMagothyScreened Interval (ft ±MSL)-222 to -288-238 to -290-435 to -465-230 to -283-375 to -425Sample IDNCIA-GW17NCIA-GW18HCGW-GW05HCGW-GW06HCGW-GW07Sample Date08/25/1008/25/1008/24/1008/24/1008/24/10References12, p. 12; 14, pp. 6,14; 18, pp. 2, 14, 85,8912, p. 12; 14, pp. 6,14; 18, pp. 2, 14, 8113, pp. 6-7; 15, pp. 5,12; 18, pp. 2, 94-9513, pp. 6-7; 15, pp. 5,12; 18, pp. 2, 6, 9713, p. 6; 15, pp. 5, 12;18, pp. 2, 6, 105VOCs (micrograms per liter [μg/L])ResultRLResultRLResultRLResultRLResultRLCarbon tetrachloride0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1-Dichloroethane0.50 U0.500.50 U0.500.50 U0.500.610.500.510.501,2-Dichloroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1-Dichloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50cis-1,2-Dichloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Chloroethane (a.k.a. Ethyl chloride)0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Tetrachloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1,1-Trichloroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Trichloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.660.50Trichlorofluoromethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1,2-Trichloro-1,2,2-trifluoroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Vinyl chloride0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50References16, pp. 5, 49, 33216, pp. 5, 50-51, 34017, pp. 6, 37, 28617, pp. 6, 38-39, 29417, pp. 6, 40, 302Abbreviations and Acronyms:ft±MSL - feet above or below mean sea levelRL - Reporting limitData Qualifiers:U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30].Notes:Italicsindicates the maximum background levelTable 1 -Background Concentrations, page 4 of 4Public Supply Well Sampling - August 2010New Cassel/Hicksville Ground Water Contamination SiteBackground Concentrations (continued)MaximumBackgroundLevelWell NameHicksville 9-1Hicksville 9-2Hicksville 10-1Jericho 9Jericho 22AquiferMagothyMagothyMagothyMagothyMagothyScreened Interval (ft ±MSL)-389 to -450-384 to -445-420 to -498-305 to -345-179 to -239Sample IDHCGW-GW10HCGW-GW11HCGW-GW13HCGW-GW14HCGW-GW15Sample Date08/24/1008/24/1008/24/1008/25/1008/25/10References13, pp. 5-6; 15, pp.5, 12; 18, pp. 2, 13,12813, p. 6; 15, pp. 5,12; 18, pp. 2, 13,13213, p. 7; 15, pp. 5,13; 18, pp. 2, 13,14613, p. 9; 15, pp. 5,15; 18, pp. 2, 7, 17013, pp. 9-10; 15, pp.5, 15; 18, pp. 2, 7,174VOCs (micrograms per liter [μg/L])ResultRLResultRLResultRLResultRLResultRLResultRLCarbon tetrachloride0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1-Dichloroethane1.20.501.40.500.50 U0.503.80.500.790.503.80.501,2-Dichloroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1-Dichloroethene0.50 U0.500.50 U0.500.50 U0.501.20.500.50 U0.501.70.50cis-1,2-Dichloroethene0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Chloroethane (a.k.a. Ethyl chloride)0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Tetrachloroethene0.50 U0.500.50 U0.500.50 U0.502.20.500.50 U0.502.20.501,1,1-Trichloroethane0.50 U0.500.50 U0.500.50 U0.501.00.500.50 U0.501.70.50Trichloroethene0.50 U0.500.50 U0.500.50 U0.502.70.500.530.502.70.50Trichlorofluoromethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1,2-Trichloro-1,2,2-trifluoroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Vinyl chloride0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50References17, pp. 6, 44-45, 33317, pp. 6, 46, 34217, pp. 7, 49-50, 36317, pp. 5, 54, 38217, pp. 5, 55-56, 392Table 1Abbreviations and Acronyms:ft±MSL - feet above or below mean sea levelRL - Reporting limitData Qualifiers:U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30].Notes:Italicsindicates the maximum background levelTable 2 -Observed Release Concentrations, page 1 of 3Public Supply Well Sampling - August 2010New Cassel/Hicksville Ground Water Contamination SiteObserved Release Sample ConcentrationsWell NameBowling Green 1Bowling Green 2Roosevelt Field 10Westbury 11AquiferMagothyMagothyMagothyMagothyScreened Interval (ft ±MSL)-350 to -410-404 to -464-418 to -504-374 to -438Sample IDNCIA-GW01NCIA-GW02NCIA-GW03NCIA-GW07NCIA-GW12Sample Date08/24/1008/24/1008/24/1008/24/1008/25/10References12, pp. 6-7; 14, pp. 5,12; 18,pp. 2, 14, 1912, pp. 6-7; 14, pp. 5, 12; 18, pp. 2, 14, 2312, p. 6; 14, pp. 5, 12;18,pp. 2, 1512, pp. 9-10; 14, pp.5, 15; 18, pp. 2, 10,VOCs (micrograms per liter [μg/L])ResultRLResultRLResultRLResultRLResultRLCarbon tetrachloride9.60.50100.50110.500.50 U0.500.50 U0.501,1-Dichloroethane6.30.501.00.501.00.500.50 U0.500.50 U0.501,2-Dichloroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1-Dichloroethene130.507.70.508.00.500.50 U0.500.50 U0.50cis-1,2-Dichloroethene2.20.506.60.506.70.500.50 U0.500.590.50Chloroethane (a.k.a. Ethyl chloride)0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Tetrachloroethene260.5013 J1069100.740.500.50 U0.501,1,1-Trichloroethane190.504.10.504.20.500.50 U0.500.50 U0.50Trichloroethene350.5040 J1011010170.501.70.50Trichlorofluoromethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1,2-Trichloro-1,2,2-trifluoroethane0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Vinyl chloride0.50 U0.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50References16, pp. 7, 32-33, 22716, pp. 7, 34, 239,54816, pp. 7, 35-36, 251,55616, pp. 7, 41-42, 28916, pp. 6, 59-60, 384Abbreviations and Acronyms:ft±MSL - feet above or below mean sea level RfD - Reference Dose Screening ConcentrationRL - Reporting limitCRSC - Cancer Risk Screening ConcentrationMCL - Maximum Contaminant LevelData Qualifiers:U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30].J - The lab used an open vial with headspace for dilution analysis of NCIA-GW02, so PCE and TCEresults (reported from the dilution) are qualified "J" (i.e., the identification of the analyte is acceptable;the reported value is an estimate) and are likely to be biased low [Ref. 16, pp. 29-30, 68, 239, 548].Notes:Boldindicates observed release concentrations (i.e., significantly exceed background)Shading indicates Level 1 concentrations (significantly exceed background and exceed benchmark[s])Dashes (---) indicate that the HRS Level I Benchmark is not establishedTable 2 -Observed Release Concentrations, page 2 of 3Public Supply Well Sampling - August 2010New Cassel/Hicksville Ground Water Contamination SiteObserved Release Sample Concentrations (continued)Well NameHicksville 4-2Hicksville 5-2Hicksville 5-3Hicksville 8-1AquiferMagothyMagothyMagothyMagothyScreened Interval (ft ±MSL)-400 to -481-348 to -435-423 to -489-440 to -491Sample IDHCGW-GW04HCGW-GW01HCGW-GW02HCGW-GW03HCGW-GW08Sample Date08/24/1008/24/1008/24/1008/24/1008/24/10References13, pp. 7-8; 15, pp. 5,12; 18, pp. 2, 13, 12413, p. 8; 15, pp. 5, 12;18, pp. 2, 6, 11413, p. 8; 15, pp. 5, 12; 18, pp. 2, 13, 14113, p. 5; 15, pp. 5, 12;18, pp. 2, 6, 109VOCs (micrograms per liter [μg/L])ResultRLResultRLResultRLResultRLResultRLCarbon tetrachloride8.50.502.20.505.90.505.90.500.50 U0.501,1-Dichloroethane380.500.50 U0.500.50 U0.500.50 U0.5020.501,2-Dichloroethane0.860.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1-Dichloroethene290.501.10.503.60.503.20.500.840.50cis-1,2-Dichloroethene230.503.90.501.10.501.10.500.50 U0.50Chloroethane (a.k.a. Ethyl chloride)1.10.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50Tetrachloroethene210.50190.50410.50400.50240.501,1,1-Trichloroethane120.501.10.502.60.502.60.500.690.50Trichloroethene440.5010010590.50580.505.60.50Trichlorofluoromethane0.830.500.50 U0.500.50 U0.500.50 U0.500.50 U0.501,1,2-Trichloro-1,2,2-trifluoroethane1.20.500.770.500.850.500.850.500.940.50Vinyl chloride0.630.500.50 U0.500.50 U0.500.50 U0.500.50 U0.50References17, pp. 6, 35-36, 27217, pp. 6, 31, 235,44917, pp. 6, 32-33, 24817, pp. 6, 34, 26017, pp. 6, 41-42, 311Abbreviations and Acronyms:ft±MSL - feet above or below mean sea level RfD - Reference Dose Screening ConcentrationRL - Reporting limitCRSC - Cancer Risk Screening ConcentrationMCL - Maximum Contaminant LevelData Qualifiers:U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30].J - The lab used an open vial with headspace for dilution analysis of NCIA-GW02, so PCE and TCEresults (reported from the dilution) are qualified "J" (i.e., the identification of the analyte is acceptable;the reported value is an estimate) and are likely to be biased low [Ref. 16, pp. 29-30, 68, 239, 548].Notes:Boldindicates observed release concentrations (i.e., significantly exceed background)Shading indicates Level 1 concentrations (significantly exceed background and exceed benchmark[s])Dashes (---) indicate that the HRS Level I Benchmark is not establishedTable 2 -Observed Release Concentrations, page 3 of 3Public Supply Well Sampling - August 2010New Cassel/Hicksville Ground Water Contamination SiteObserved Release Sample Concentrations (concluded)HRS Level IBenchmarks(Drinking Water)Well NameHicksville 8-3Hicksville 9-3TOH-Levittown 2AAquiferMagothyMagothyMagothyScreened Interval (ft ±MSL)-410 to -495-432 to -509-474 to -574Sample IDHCGW-GW09HCGW-GW12HCGW-GW16Sample Date08/24/1008/24/1008/24/10References13, p. 5; 15, pp. 5, 12;18, pp. 2, 13, 13613, p. 6; 15, pp. 5, 13;18, pp. 2, 13, 15513, p. 4; 15, pp. 5, 13;18, pp. 2, 14Ref. 1, p. 51593VOCs (micrograms per liter [μg/L])ResultRLResultRLResultRLMCLRfDCRSCCarbon tetrachloride1.80.500.50 U0.500.50 U0.505260.661,1-Dichloroethane0.50 U0.501.40.501.80.50---3,700---1,2-Dichloroethane1.10.500.50 U0.500.50 U0.505---0.941,1-Dichloroethene0.50 U0.500.50 U0.502.90.5071,800---cis-1,2-Dichloroethene1.70.500.730.5030.5070360---Chloroethane (a.k.a. Ethyl chloride)0.50 U0.500.50 U0.500.50 U0.50---------Tetrachloroethene160.501.30.501.50.5053601.61,1,1-Trichloroethane0.50 U0.500.50 U0.501.70.50200------Trichloroethene240.50565.0110.505110.21Trichlorofluoromethane0.50 U0.500.50 U0.500.50 U0.50---11,000---1,1,2-Trichloro-1,2,2-trifluoroethane4.80.507.90.500.50 U0.50---------Vinyl chloride0.50 U0.500.50 U0.500.50 U0.5021100.057References17, pp. 6, 43, 32217, pp. 7, 47-48, 351,45717, pp. 7, 51, 371Ref. 2, pp. 11-15, 19Abbreviations and Acronyms:ft±MSL - feet above or below mean sea level RfD - Reference Dose Screening ConcentrationRL - Reporting limitCRSC - Cancer Risk Screening ConcentrationMCL - Maximum Contaminant LevelData Qualifiers:U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30].J - The lab used an open vial with headspace for dilution analysis of NCIA-GW02, so PCE and TCEresults (reported from the dilution) are qualified "J" (i.e., the identification of the analyte is acceptable;the reported value is an estimate) and are likely to be biased low [Ref. 16, pp. 29-30, 68, 239, 548].Notes:Boldindicates observed release concentrations (i.e., significantly exceed background)Shading indicates Level 1 concentrations (significantly exceed background and exceed benchmark[s])Dashes (---) indicate that the HRS Level I Benchmark is not established27 GW

- Observed Release (continued)

Attribution:

EPA has not yet i dentified a surface source of the ground water contaminants in the public supply wells

. The compounds found in the wells are not naturally occurring, and non

- detect ed concentrations in some upgradient public supply wells

show that th ey are not ubiquitous throughout the region [ Figure 1 ]. C hlorinated solvents (e.g., TCE, PCE, and carbon

tetrachloride ) are man

- made compounds commonly used in commercial/industrial operations such as dry cleaning and metal degreasing, while other contaminants such as cis

- 1,2

- DCE are common breakdown product s of PCE and TCE [Ref.

2 5, pp. 1

- 20; 26, p. 1; 27, p. 1 ]. The NCHGWC site is located in a heavily developed area consisting of industrial, commercial, and residential land, where a variety of past industrial and commercial activities could have resulted in the ground water contamination and where hundreds of contaminated sites have been identified [Ref. 4, pp. 1

- 2; 18, pp. 3

- 4,

19

- 27, 40

- 44, 109

- 118, 124

- 126, 136

- 145, 155

- 159 ; 19, pp. 3

- 34 ].

NYSDEC and EPA have made signif icant efforts to identify the specific source(s) of ground water contamination. For

instance

, i n 1988, NYSDEC listed the NCIA, located just north of the Bowling Green wells, as a Class 2 site (Significant threat to the public health or environment

- acti on required) in the New York State Registry of Inactive Hazardous Waste Disposal Sites (the Registry) [Ref. 8, pp. 7

- 9; 9, p. 7]

. The NCIA was d evelop ed in the 1950s, many of the properties have housed various businesses over the years , and a wide variety of past commercial and industrial activities conducted

within the area could have resulted in VOC contamination [Ref. 8, pp. 8

- 15, 54

- 62; 20, pp. 4

- 5, 68]

. NYSDEC investigated 17 facilities at the NCIA to varying degrees from 1994

- 1999, including soil and ground water sampling , and

has since conducted or overseen r emedial activities at s ome facilities [Ref. 8, pp. 8

- 18 ; 9, p. 7] . Despite the investigative and remedial efforts, NYSDEC has been unable to identify the specific source(s) of contamination in t he public supply

wells and has identified contaminated ground water south of the NCIA as a separate o perable u nit (OU3) [Ref. 8, p. 8; 20, pp. 4

- 17]

. The NCIA investigation did not consider the Hicksville wells or other potential sources to the north and

east , but other investigations to the northeast of the NCIA have indicated the presence of numerous other potential source areas [Ref. 31 , pp. 7

- 40 ; 32, pp. 14

- 43, 99

- 100 ].

EPA conducted a database search centered on Hicksville Water District Plant 5 (We lls 5

- 2 and 5

- 3) . The findings

indicate d that there are 20 facilities associated with F001 to F005 wastes (i.e., spent halogenated solvents that might contain PCE or TCE) located within approximately 1 mile of the wells [Ref. 19, pp. 1 6 1

- 10 1 8]. T he envir onmental

database search indicated that there are 3 Resource C onservation and Recovery Act (RCRA) corrective action sites, 8 RCRA Generators, 29 State

- listed hazardous waste sites, 3 landfills, 175 leaking underground storage tank (LUST) sites, and 4 regi s tered drycleaners located within 1.5 miles of Plant 5 [Ref. 19, pp. 32

- 38, 1001

- 1018 ]. Although there is this multitude of facilities in the region that are or could be associated with the site contaminants, there is not sufficient

evidence to attribute t he ground water contamination in the public supply wells to any specific facility(ies); therefore, there is no identified source(s) of contamination.

Hazardous Substances Released:

Carbon tetrachloride CAS No. 000056

- 23

- 5 1,1

- Dichloroethane (DCA) CAS No. 00007 5

- 34

- 3 1,2

- Dichloroethane (DCA) CAS No. 000 107

- 06

- 2 1,1

- Dichloroethylene (1,1

- DCE) CAS No. 00007 5

- 35

- 4

Cis

- 1,2

- Dichloroethylene (cis

- 1,2

- DCE) CAS No. 000156

- 59

- 2

Chloroethane (a.k.a

. Ethyl chloride ) CAS No. 000075

- 00

- 3 Tetrachloroethylene (PCE) CAS No. 000127

- 18

- 4 1,1,1

- Trichloroethane ( 1,1,1

- TCA) CAS No. 000071

- 55

- 6 Trichloroethylene (TCE) CAS No. 000079

- 01

- 6

Trichlorofluoromethane (a.k.a. Freon 11) CAS No. 000075

- 69

- 4 1,1,2

- Trichloro

- 1,2,2

- trifluoroethane (a.k.a. CFC

- 113) CAS No. 000076

- 13

- 1 Vinyl chloride CAS No. 000075

- 01

- 4

================================================================================== Ground Water Observed Release Factor Value: 55028 GW

- Waste Characteristics

3.2 WASTE CHARACTERISTICS

3.2.1 Toxicit y/Mobility

Hazardous Substance Source

Numbers Toxicity

Factor Value Mobility

Factor Value Toxicity/ Mobility Reference

Carbon tetrachloride 1, OR 1,000 1.0 1,000 2, p. 4
1,1

- DCA 1, OR 10 1.0 10 2, p. 5
1,2

- DCA 1, OR 100 1.0 100 2, p. 5
1,1

- DCE 1, OR 1 00 1.0 100 2, p. 6

cis

- 1,2

- DCE 1, OR 100 1.0 100 2, p. 6 Ethyl chloride 1, OR 1 1.0 1 2, pp. 7, 17

PCE 1, OR 100 1.0 100 2, p. 8
1,1,1

- TCA 1, OR 1 1.0 1 2, p. 9

TCE 1, OR 10,000 1.0 10,000 2, p. 1 9

Freon 11 1, OR 10 1.0 10 2, p. 9

CFC

- 113 1, OR

--- --- --- 2, p. 9, 16

- 18 Vinyl chloride 1, OR 10,000 1.0 10,000 2, p. 1 0

OR = Observed Release

3.2.2 Hazardous Waste Quantity

Source Number Source Hazardous Waste Quantity (HWQ) Value (Section 2.4.2.1.5) Is source hazardous constituent quantity data c omplete? (yes/no)

1 14,814.81 4 No

Sum of Values: 1 4,814 (rounded to nearest integer as specified in HRS Section 2.4.2.2)

The sum corresponds to a hazardous waste quantity factor value of 1 0,000 in Table 2

- 6 of the HRS [Ref. 1, p. 51591].

Therefor e, a hazardous waste quantity factor value of 10

, 0 00 is assigned for the ground water pathway [ Ref. 1, p p 51591

- 51592]

.

3.2.3 Waste Characteristics Factor Category Value

TCE and vinyl chloride correspond to the toxicity/mobility factor value of 10,000, as shown in Section 3.2.1.

Toxicity/Mobility Factor Value (10,000) x Hazardous Waste Quantity Factor Value (10 ,00 0): 1 x 10 8

The product (1 x 10 8 ) corresponds to a Waste Characteristics Factor Category Value of 100 in Table 2

- 7 of the HRS [Ref. 1, p. 51592].

================================================================================== Hazardous Waste Quantity Factor Value: 10 ,00 0 Waste Characteristics Factor Category Value: 10029 GW

- Targets

3.3 TARGETS

The blended Town of H empstead water supply system consists of 28 active wells serving 112,592 people , the blended Hicksville system consists of 14 acti ve wells serving 47,810 people , and the blended Westbury system consists of 1 0 active wells serving 20

, 500 people [Ref. 1 8 , p p

. 1, 18, 2 9 , 9 1 ]

. N o single well in any of these system s contributes more than 40 percent of the total blended water s upply , so each population is apportioned equally among the system components (i.e., the active wells) [Ref. 1, p. 51603; 1 8 , pp. 1

- 2, 1 8, 29, 9 1 ]. Therefore, each Town of Hempstead well is apportioned a population of 4,021 people , each Hicksville well is apportioned a population of 3,415 people, and each Westbury well is apportioned a population of 2,050 people [Ref. 1 8 , p p

. 1

- 2 ]. The app ortioned populations and levels of contamination for contaminated wells at the site are presented below:

Well Distance from Source (mi.)* Population Level I Conc. / Level II Conc. /

Potential Contam ination ** Reference s

Bowling Green 1 0.72 4,021 Level I Fi gure 1; 18, pp. 1

- 2, 18 Bowling Green 2 0.73 4,021 Level I Figure 1; 18, pp. 1

- 2, 18

Roosevelt Field 10 1.99 4,021 Level I Figure 1; 18, pp. 1

- 2, 18

Levittown Well 2A 1.34 4,021 Level I Figure 1; 18, pp. 1

- 2, 18

Hicksville Well 4

- 2 0.86 3,415 Level I F igure 1; 18, pp. 1

- 2, 9 1

Hicksville Well 5

- 2 0.31 3,415 Level I Figure 1; 18, pp. 1

- 2, 9 1

Hicksville Well 5

- 3 0.31 3,415 Level I Figure 1; 18, pp. 1

- 2, 9 1

Hicksville Well 8

- 1 1.86 3,415 Level I Figure 1; 18, pp. 1

- 2, 9 1

Hicksville Well 8

- 3 1.84 3,415 L evel I Figure 1; 18, pp. 1

- 2, 9 1

Hicksville Well 9

- 3 2

. 24 3,415 Level I Figure 1; 18, pp. 1

- 2, 9 1 Westbury Well 11 2.11 2,050 Level I I Figure 1; 18, pp. 1

- 2, 29

* Distance is measured from the center of the area of observed ground water contamination [ Figure 1].

** Maximum Contaminant Level/Maximum Contaminant Level Goal (MCL/MCLG), Reference Dose Screen

Concentration (RfD), and Cancer Risk Screen Concentration (CRSC) were used as benchmarks to evaluate the level of contamination [Ref. 1, p. 51593]. T hese benchmarks are not assigned for ethyl chloride or CFC

- 113 [Ref. 2, pp. 13

- 18]. Applicable benchmarks for the other contaminants detected in the observed release, presented here in μg/L for consistency with reported data, are as follows:

Substance MC L/MCLG RfD CRSC Reference(s)

Carbon tetrachloride 5 26 0.66 2, p. 11
1,1

- DCA

--- 3,700

--- 2, p. 12
1,2

- DCA 5

--- 0.94 2, p. 12
1,1

- DCE 7 1,800

--- 2, p. 12

cis

- 1,2

- DCE 70 360

--- 2, p. 12

PCE 5 360 1.6 2, p. 14
1,1,1

- TCA 200

--- --- 2, p. 14

TCE 5 11 0.21 2, p. 1 9

Freon 11

--- 11,000

--- 2, p p. 1 4 , 18 Vinyl chloride 2 110 0.057 2, p. 1 530 GW

- Targets (continued)

Level I Concentrations

Well Sample Substance Conc. (μg/L) Benchmark (μg/L) Reference(s) Bowling

Green Well 1 NCIA

- GW01 Carbon

tetrachloride 9.6 0

. 6 6 (CRSC) 5 (MCL) 2, p. 9 ; 1 6 , p. 33

1,1

- DCE 13 7 (MCL) 2, p. 10; 16, p

. 32

PCE 26 1.6 (CRSC) 5 (MCL) 2, p. 11 ; 16, p

. 33

TCE 35 0.21 (CRSC) 5 (M CL) 11 (RfD) 2, p. 1 5 ; 16, p

. 33

Bowling

Green Well 2 NCIA

- GW02 /

NCIA

- GW03 (field duplicates) Carbon

tetrachloride 10 / 11 0

. 6 6 (CRSC) 5 (MCL) 2, p. 9 ; 16, p p. 34,

36
1,1

- DCE 7.7 / 8.0 7 (MCL) 2, p. 10; 16, p p. 34

- 35

PCE 13 J / 69 1.6 (CRSC) 5 (MCL ) 2, p. 11 ; 16, p p. 34, 36

TCE 40 J / 110 0.21 (CRSC) 5 (MCL) 11 (RfD) 2, p. 15 ; 16, p p. 34, 36

Roosevelt

Field Well 10 NCIA

- GW07 TCE 17 0.21 (CRSC) 5 (MCL) 11 (RfD) 2, p. 15 ; 16, p

. 42

Levittown

Well 2A HCGW

- GW16 TCE 11 0.21 (CRSC) 5 (MCL) 11 (RfD) 2 , p. 19 ; 17, p. 51

Hicksville

Well 4

- 2 HCGW

- GW04 Carbon

tetrachloride 8.5 0

. 6 6 (CRSC) 5 (MCL) 2, p. 11 ; 17, p. 36

1,1

- DCE 29 7 (MCL) 2, p. 12; 17, p. 35

PCE 21 1.6 (CRSC) 5 (MCL) 2, p. 14 ; 17, p. 36

TCE 44 0.21 (CRSC) 5 (MCL) 11 (RfD) 2, p. 19 ; 17, p. 36

Vinyl chloride 0.63 0.057 (CRSC) 2, p. 15; 17, p. 35

Hicksville

Well 5

- 2 HCGW

- GW01 Carbon

tetrachloride 2.2 0

. 6 6 (CRSC) 2, p. 11 ; 17, p

. 31

PCE 19 1.6 (CRSC) 5 (MCL) 2, p. 14 ; 17, p . 3 1

TCE 100 0.21 (CRSC) 5 (MCL) 11 (RfD) 2, p. 19 ; 17, p . 3 1

Hicksville

Well 5

- 3 HCGW

- GW02

/ HCGW

GW03 (field duplicates) Carbon

tetrachloride 5.9 / 5.9 0

. 6 6 (CRSC) 5 (MCL) 2, p. 11; 17, p p. 33

- 34

PCE 41 / 40 1.6 (CRSC) 5 (MCL) 2, p. 14 ; 17, p p. 33

- 34

TCE 59 / 58 0.21 (CRSC) 5 (MCL) 11 (RfD) 2, p. 19 ; 17, p p. 33

- 3431 GW

- Targets (continued)

Level I Concentrations (continued)

Well Sample Substance Conc. (μg/L) Benchmark (μg/L) Reference(s)

Hicksville

Well 8

- 1 HCGW

- GW08 PCE 24 1.6 (CRSC) 5 (MCL) 2, p. 14 ; 17, p. 42

Hicksville

Well 8

- 3 HCGW

- GW09 Carbon

tetrachloride 1.8 0

. 6 6 (CRSC) 2, p. 11 ; 17, p. 43

1,2

- DCA 1.1 0.94 (CRSC) 2, p. 12; 17, p. 43

PCE 16 1.6 (CRSC) 5 (MCL) 2, p. 14 ; 17, p. 43

TCE 24 0.21 (CRSC) 5 (MCL) 11 (RfD) 2, p. 19 ; 17, p. 43

Hicksville

Well 9

- 3 HCGW

- GW12 TCE 56 0.21 (CRSC) 5 (MCL) 11 (RfD) 2, p. 19 ; 17, p. 48

Level II Concentrations

Well Sample Substance Conc. (μg/L ) Benchmark (μg/L) Reference(s) Bowling

Green Well 1 NCIA

- GW01 c is

- 1,2

- DCE 2.2 70 (MCL) 2, p. 12 ; 16, p. 3 2
1,1,1

- TCA 19 200 (MCL) 2, p. 1 4 ; 16, p. 3 3 Bowling

Green Well 2 NCIA

- GW02 /

NCIA

- GW03 (field duplicates) c is

- 1,2

- DCE 6.6 / 6.7 70 (MCL) 2, p. 1 2 ; 16, pp. 34,

36

Levittown

Well 2A HCGW

- GW16 cis

- 1,2

- DCE 3.0 70 (MCL) 2, p. 12 ; 17, p. 51

Westbury

Well 11 NCIA

- GW12 cis

- 1,2

- DCE 0.59 70 (MCL) 2, p. 12 ; 16, p. 59

Hicksville

Well 4

- 2 HCGW

- GW04 1,1

- DCA 38 3,700 (RfD) 2, p. 1 2 ; 17, p. 36
1,2

- DCA 0.86 0.94 (CRSC) 2, p. 12; 17, p. 3 6

cis

- 1,2

- DCE 23 70 (MCL) 2, p. 1 2 ; 17, p. 36 Ethyl chloride 1.1 none established 2, p. 13 , 17 ; 17, p. 3 5
1,1,1

- TCA 12 200 (MCL) 2, p. 14 ; 17, p. 36

Freon 11 0.83 11 ,000 (RfD) 2, p. 1 4 , 18 ; 17, p. 3 5

CFC

- 113 1.2 none established 2, p p. 14

- 18 ; 17, p. 35

Hicksville

Well 5

- 2 HCGW

- GW01 cis

- 1,2

- DCE 3.9 70 (MCL) 2, p. 12 ; 17, p. 31

CFC

- 113 0.77 none established 2, pp. 14

- 18; 17, p. 31

Hicksville

Well 5

- 3 HCGW

- GW02

HCGW

- GW03 (field duplicates) cis

- 1,2

- DCE 1.1 / 1.1 70 (MCL) 2, p. 12; 17, pp. 3 2,

34

CFC

- 113 0.85 / 0.85 none established 2, pp. 14

- 18; 17, pp.

3 2, 34

Hicksville

Well 8

- 1 HCGW

- GW08 CFC

- 113 0.94 none established 2, pp. 14

- 18; 17, p. 41

Hicksville

Well 8

- 3 HCGW

- GW09 cis

- 1,2

- DCE 1.7 70 (MCL) 2, p. 12 ; 1 7, p. 43

CFC

- 113 4.8 none established 2, pp. 14

- 18; 17, p. 43

Hicksville

Well 9

- 3 HCGW

- GW12 cis

- 1,2

- DCE 0.73 70 (MCL) 2, p. 12 ; 17, p. 48

CFC

- 113 7.9 none established 2, pp. 14

- 18; 17, p. 4732 GW

- Nearest Well/Population

3.3.1 Nearest Well

As ide ntified in Section 3.3, several drinking water wells are subject to Level I concentrations. Therefore, a nearest well factor value of 50 is assigned [Ref. 1, pp. 51602

- 51603].

============================================================================== ==== Nearest Well Factor Value: 50

3.3.2 Population

3.3.2.2 Level I Concentrations

As identified in Section 3.3, ten drin king water wells are subject to Level I concentrations. The populations assigned to the wells are also explained in Section 3.3

.

Level I Well Population Reference(s) Bowling Green Well 1 4

, 021 2, p. 9 ; 16, pp. 32

- 33; 1 8 , pp. 1

- 2, 1 8 Bowling Green Well 2 4,021 2, p. 9 ; 16, pp. 34

- 36; 1 8 , pp. 1

- 2, 1 8

Roosevelt Field Well 10 4,021 2, p. 9 ; 16, p. 42; 1 8 , pp. 1

- 2, 1 8

Levittown We ll 2A 4,021 2, p. 9 ; 17, p. 51; 18, pp. 1

- 2, 29

Hicksville Well 4

- 2 3,415 2, p. 9 ; 17, pp. 35

- 36; 18, pp. 1

- 2, 9 1

Hicksville Well 5

- 2 3,415 2, p. 9 ; 17, p. 31; 18, pp. 1

- 2, 9 1

Hicksville Well 5

- 3 3,415 2, p. 9 ; 17, pp. 32

- 34; 18, pp. 1

- 2, 9 1

Hicksville Well 8

- 1 3,415 2, p. 9 ; 17, p. 42; 18, pp. 1

- 2, 9 1

Hicksville Well 8

- 3 3,415 2, p. 9 ; 17, p. 43; 18, pp. 1

- 2, 9 1

Hicksville Well 9

- 3 3,415 2, p. 9 ; 17, p. 48; 18, pp. 1

- 2, 9 1

============================================================================ ====== Population Served by Level I Wells: 36

, 574 Level I Concentrations Factor Value: 365

, 740

3.3.2.3 Level II Concentrations

As identified in Section 3.3, one drinking water well is subject to Level II concentrations but is not subject to Level I

con centrations. The population assigned to the well is also explained in Section 3.3.

Level II Well Population Reference(s) Westbury Well 11 2,050 2, p. 9 ; 16, p. 59; 1 8 , pp. 1

- 2, 29

======================================================================= =========== Population Served by Level II Wells: 2

, 050 Level II Concentrations Factor Value: 2 ,0 50

3.3.2.4 Potential Contamination

There are numerous public supply wells in the site vicinity that are not currently subject to Level I or Level II

concen trations [Figure 1; Table 1]. However, s ince Level I and Level II concentrations result in a maximum score of 100.00 for the ground water migration pathway, the Potential Contamination Factor Value was not scored.

======================================== ========================================= Potential Contamination Factor Value: NS33 GW

- Resources/Wellhead Protection Area

3.3.3 Resources

Ground water is the sole source of water supply for Nassau County [Ref. 21, p. 1] and is most likely used for major water recreation areas such as public swimming pools in the site area . However, s ince Level I and Level II concentrations result in a maximum score of 100.00 for the ground water migration pathway, the Resources Factor Value was not scored.

================================================================================== Resources Factor Value: NS

3.3.4 Wellhead Protection Area

The Wellhead Protection Program for New York (September 1990) was developed in accordance with Sec tion 1428 of the Safe Drinking Water Act and approved by EPA between 1990 and 1991 [Ref. 33 , p. 1; Ref. 34 , p. 1]. The document sets forth wellhead protection area delineation policies for drinking water wells in the State, including a specific baseline

d esignation for all public supply wells in the Magothy a quifer [Ref. 33 , pp. 15

- 25]. The public supply wells showing observed release concentrations at the NCHGWC site all withdraw water from the Magothy a quifer [Ref. 18, pp. 1

- 2

, 5

- 16 ]. Based on this inf ormation, observed ground water contamination associated with the site lies within a designated wellhead protection area, and a Wellhead Protection Area Factor Value of 20 is assigned [Ref. 1, p. 51604].

=================================================== ================================ Wellhead Protection Area Factor Value: 20