HRS DOCUMENTATION RECORD--REVIEW COVER SHEET

Name of Site: New Cassel/Hicksville Ground Water Contamination

CERCLIS ID No.: NY0001095363

Date Prepared: March 2011

Contact Persons

Site Investigations: Guy Bobersky (518) 402-9621

New York 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, Components, 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 score.
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: * Southern 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]

Latitude: 40 ̊ 45' 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 latitude/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 southern 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 considers 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 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 100.00

Surface Water Pathway Not Scored

Soil Exposure Pathway Not Scored

Air Pathway Not Scored

HRS SITE SCORE 50.00
2

WORKSHEET FOR COMPUTING HRS SITE SCORE

New Cassel/Hicksville Ground Water Contamination

S S2

1. Ground Water Migration Pathway Score (Sgw) 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 Water Migration Component Not Scored

(from Table 4-25, line 28)

2c. Surface Water Migration Pathway Score (Ssw) Not Scored

Enter the larger of lines 2a and 2b as the pathway score.

3. Soil Exposure Pathway Score (Ss) Not Scored

(from Table 5-1, line 22)

4. Air Migration Pathway Score (Sa) Not Scored

(from Table 6-1, line 12)

5. Total of Sgw2 + Ssw2 + Ss

2 + Sa2 10,000

6. HRS Site Score Divide the value on line 5

 by 4 and take the square root 50.00
3

GROUND WATER MIGRATION PATHWAY SCORESHEET

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 scored

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 * 10,000

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) ** 367,790

9. Resources 5 not scored

10. Wellhead Protection Area 20 20

11. Targets (lines 7+8d+9+10) ** 367,860

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

13. Ground Water Migration Pathway Score (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 complete 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/sites/npl/hrsres/tools/scdm.htm. Excerpts accessed and downloaded 

September 17, 2010. [19 pages] 

3.	 EPA. Superfund Information Systems, CERCLIS Database, 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. (WESTON). 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 Groundwater, Town of North Hempstead, Nassau County. 

Prepared for New York State Department of Environmental Conservation (NYSDEC). September 2000. 

[937 pages] 

8.	 NYSDEC Division of Environmental Remediation. Record of Decision, New Cassel Industrial Area Sites, 

Town of North Hempstead, Nassau County, New York, 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 Program, 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 District 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] 

4 
 

 

 

REFERENCES (continued) 

Reference 

Number Description of the Reference 

15.	 Capriglione, Michele, WESTON. Sampling Trip Report, 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 Engineering, P.C. (HDR). Pre-Design Investigation 

Evaluation Report, New Cassel Industrial 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 County 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] 

5 
6

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_search=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 Document an Observed 

Release and Observed Contamination. Office of Emergency and Remedial Response. November 1996. 

[18 pages]

30. Gilliland, Gerry, WESTON. 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 pages]

31. ESC Engineering of New York, P.C. and Stearns and Wheeler, LLC. Vishay General Semiconductor, Inc., 

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 

Incorporated 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, 2011. [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 with volatile organic compounds (VOC), recognized by

Nassau County Department of Health (NCDH) in 1986 [Ref. 6, pp. 10-15, 23-25, 62]. The plume affects several public 

supply wells; file documents indicate that Town of Hempstead – Bowling Green Wells 1 and 2 have shown the presence 

of VOCs since approximately 1988 [Ref. 6, p. 12; 7, p. 56; 8, p. 62; 9, pp. 6-7, 25-31]. 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. 10, pp. 1-252]. Contaminants reported in at 

least one well included carbon tetrachloride; 1,1-dichloroethane (DCA); 1,2-DCA; 1,1- dichloroethylene (DCE); cis-1,2-

DCE; tetrachloroethylene (PCE); 1,1,1-trichloroethane (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. 11, pp. 14-17].

U.S. Environmental Protection Agency (EPA) collected raw (i.e., pre-treatment) ground water samples from the Bowling 

Green wells, Hicksville wells, and other nearby 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, 10-16]. 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 Water 

District Well 11 [Figure 1; Table 2; Ref. 16, pp. 29-60; 17, pp. 29-58]. The concentrations of carbon tetrachloride; 1,1-

DCE; PCE; and TCE exceeded the Maximum Contaminant Levels (MCL) in several wells [Table 2; Ref. 2, pp. 11-12, 

14, 19]. Samples collected from upgradient, background wells showed non-detected or low concentrations for all 

contaminants of concern [Figure 1; Table 2; Ref. 14, pp. 10-16; 15, pp. 10-16; 16, pp. 29-60; 17, pp. 29-58]. The total 

population associated with the 11 wellsshowing 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 consisting 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; 18, pp. 3-4, 19-27, 40-44, 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 Bowling 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 some

facilities [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. 20, pp. 4-17]. 

The NCHGWC site is underlain by the upper glacial aquifer (UGA), an unconfined aquifer consisting of Upper 

Pleistocene, poorly-sorted sand and gravel deposits, from ground surface 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 Magothy formation lying 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 formations [Ref. 8, p. 20; 20, p. 5]. The 

Magothy is approximately 500-580 feet thick at the site, and it is underlain by the Raritan Clay confining unit, which is 

about 180-200 feet thick at the site [Ref. 20, p. 5; 30, pp. 1-10]. The underlying Lloyd Sand aquifer, which is

approximately 250-330 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]. The Magothy aquifer is the primary source of drinking 

water in Nassau County, and the Lloyd Aquifer is used to a lesser extent [Ref. 18, pp. 5-16; 21, pp. 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 

CLIENT NAME: DATE: FIGURE #:

PROJECT: 

SOURCES: TITLE: 

<!

!

!

!

!

!

!!

!

!!

!

!

!

!

!!

!

!

!

!

<

<

<

<

<

<<

<

<<

<

<

<

<

<<

<

<

<

<

!

!

!!

!

!

!

!!

!

<

<

<<

<

<

<

<<

<

!(

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 

EPA January 2011 1

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 2,000 0 4,000

Graphic Scale In Feet 
9

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 attributed 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. 29-60; 17, pp. 29-58]. 

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

Hempstead – Bowling Green Wells 1 and 2 have shown the presence of VOCs since approximately 1988 [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. 10, pp. 1-252]. Contaminants reported in at least one of these wells included 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. 11, pp. 14-17].

In August 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, 10-16]. 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; Tables 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; Ref. 2, pp. 11-12, 14, 19]. Samples collected from 

upgradient, background wells showed non-detected or low concentrations for all contaminants of concern [Figure 1; 

Table 1; Ref. 14, pp. 10-16; 15, pp. 10-16; 16, pp. 29-60; 17, pp. 29-58].

Note: The source 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 VOCs [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) showed 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 present 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 sites in Nassau County [Ref. 28, pp. 1-3]. The background 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 the west-southwest, and Old Roosevelt Field Contaminated GW Area to the west) [Ref. 28, 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 identified 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 shown 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 2008 provide qualitative evidence of the presence of chlorinated solvents in the 

Bowling Green Wells 1 and 2 and Hicksville Wells 5-2 and 5-3. Ground water samples collected by EPA in 2010 

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 

indicates that VOCs were present in the wells at least since 1988 and that chlorinated solvents 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 34 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-detected to 2 μg/L

o 1,1-DCE: non-detected to 3 μg/L

o 1,1,1-TCA: non-detected to 3 μg/L

o 1,1-DCA: non-detected to 1 μg/L

Historic Sampling 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 wells, 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 32.4 μg/L

o Carbon tetrachloride: non-detected to 7 μg/L

o Cis-1,2-DCE: non-detected to 6.6 μg/L

o 1,1-DCE: non-detected to 5.5 μg/L

o 1,1,1-TCA: non-detected to 4.1 μg/L

o 1,2-DCA: non-detected 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-detected to 9 μg/L

o Cis-1,2-DCE: non-detected to 1.5 μg/L

o 1,1-DCE: non-detected to 12 μg/L

o 1,1,1-TCA: non-detected to 4.7 μg/L
12

SD- Hazardous Substances (continued)

Source No.: 1

EPA Sampling Event – Ground Water Samples: August 2010

In August 2010, EPA collected raw (i.e., pre-treatment) ground water samples from the Bowling Green 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, 10-16]. 

The samples were analyzed by the EPA Region 2 Laboratory, not by a Contract Laboratory Program (CLP) laboratory 

through the CLP [Ref. 16, pp. 15-60; 17, pp. 16-58]. 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-

60; 17, pp. 16-58; 23, pp. 1-70; 24, pp. 1-28]. The CLP SOW and internal laboratory SOP are both based on EPA 

Method 524.2 purge-and-trap gas chromatograph/mass spectrometer (GC/MS) techniques [Ref. 23, p. 21; 24, p. 3].

With few exceptions, the EPA laboratory was able to achieve reporting limits (RL) of 0.50 μg/L (equal to the CLP 

Contract-Required Quantitation Limits [CRQL]) for all contaminants of concern [Ref. 16, pp. 29-68; 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 that 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, 571-572; 17, pp. 5-26, 472].

The EPA analytical results confirmed the presence of VOCs at observed release concentrations (i.e., significantly above 

background) in several well samples, as presented below [Ref. 16, pp. 29-60; 17, pp. 29-58]. Samples collected from 

background wells showed non-detected (ND) or comparatively low concentrations for all contaminants of concern [Ref. 

14, pp. 10-16; 15, pp. 10-16; 16, pp. 29-60; 17, pp. 29-58]. Additional information regarding background levels is 

presented in Section 3.1.1.

Hazardous Substance Sample Number Date 

Sampled

Result 

(μg/L)

RL 

(μg/L)

References

Carbon tetrachloride NCIA-GW01 08/24/2010 9.6 0.50 16, pp. 7, 33, 227

NCIA-GW02 08/24/2010 10 0.50 16, pp. 7, 34, 239

NCIA-GW03 08/24/2010 11 0.50 16, pp. 7, 36, 251

HCGW-GW01 08/24/2010 2.2 0.50 17, pp. 6, 31, 235

HCGW-GW02 08/24/2010 5.9 0.50 17, pp. 6, 33, 248

HCGW-GW03 08/24/2010 5.9 0.50 17, pp. 6, 34, 260

HCGW-GW04 08/24/2010 8.5 0.50 17, pp. 6, 36, 272

HCGW-GW09 08/24/2010 1.8 0.50 17, pp. 6, 43, 322

Maximum 

background*

08/24/2010

08/25/2010

ND 0.50 16, pp. 5, 43-51, 58; 17, pp. 5-

7, 37-40, 44-46, 49-50, 54-56

1,1-DCA HCGW-GW04 08/24/2010 38 0.50 17, pp. 6, 36, 272

Maximum background 

(HCGW-GW14)*

08/25/2010 3.8 0.50 16, pp. 5, 43-51, 58; 17, pp. 5-

7, 37-40, 44-46, 49-50, 54-56

1,2-DCA HCGW-GW04 08/24/2010 0.86 0.50 17, pp. 6, 36, 272

HCGW-GW09 08/24/2010 1.1 0.50 17, pp. 6, 43, 322

Maximum 

background*

08/24/2010

08/25/2010

ND 0.50 16, pp. 5, 43-51, 58; 17, pp. 5-

7, 37-40, 44-46, 49-50, 54-56
13

SD- Hazardous Substances (continued)

Source No.: 1

EPA Sampling Event – Ground Water Samples: August 2010 (continued)

Hazardous Substance Sample Number Date 

Sampled

Result 

(μg/L)

RL 

(μg/L)

Reference

1,1-DCE NCIA-GW01 08/24/2010 13 0.50 16, pp. 7, 32, 227

NCIA-GW02 08/24/2010 7.7 0.50 16, pp. 7, 34, 239

NCIA-GW03 08/24/2010 8.0 0.50 16, pp. 7, 35, 251

HCGW-GW04 08/24/2010 29 0.50 17, pp. 6, 35, 272

Maximum background 

(NCIA-GW16)*

08/25/2010 1.7 0.50 16, pp. 5, 43-51, 58; 17, pp. 5-

7, 37-40, 44-46, 49-50, 54-56

cis-1,2-DCE NCIA-GW01 08/24/2010 2.2 0.50 16, pp. 7, 32, 227

NCIA-GW02 08/24/2010 6.6 0.50 16, pp. 7, 34, 239

NCIA-GW03 08/24/2010 6.7 0.50 16, pp. 7, 36, 251

NCIA-GW12 08/25/2010 0.59 0.50 16, pp. 6, 59, 384

HCGW-GW01 08/24/2010 3.9 0.50 17, pp. 6, 31, 235

HCGW-GW02 08/24/2010 1.1 0.50 17, pp. 6, 32, 248

HCGW-GW03 08/24/2010 1.1 0.50 17, pp. 6, 34, 260

HCGW-GW04 08/24/2010 23 0.50 17, pp. 6, 36, 272

HCGW-GW09 08/24/2010 1.7 0.50 17, pp. 6, 43, 322

HCGW-GW12 08/24/2010 0.73 0.50 17, pp. 7, 48, 351

HCGW-GW16 08/24/2010 3.0 0.50 17, pp. 7, 51, 371

Maximum 

background*

08/24/2010

08/25/2010

ND 0.50 16, 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-GW04 08/24/2010 1.1 0.50 17, pp. 6, 35, 272

Maximum 

background*

08/24/2010

08/25/2010

ND 0.50 16, pp. 5, 43-51, 58; 17, pp. 5-

7, 37-40, 44-46, 49-50, 54-56

PCE NCIA-GW01 08/24/2010 26 0.50 16, pp. 7, 33, 227

NCIA-GW02 08/24/2010 13 J** 10 16, pp. 7, 34, 239, 548; 24, p. 

18

NCIA-GW03 08/24/2010 69 10 16, pp. 7, 36, 251, 556; 24, p. 

18

HCGW-GW01 08/24/2010 19 0.50 17, pp. 6, 31, 235, 449

HCGW-GW02 08/24/2010 41 0.50 17, pp. 6, 33, 248

HCGW-GW03 08/24/2010 40 0.50 17, pp. 6, 34, 260

HCGW-GW04 08/24/2010 21 0.50 17, pp. 6, 36, 272

HCGW-GW08 08/24/2010 24 0.50 17, pp. 6, 42, 311

HCGW-GW09 08/24/2010 16 0.50 17, pp. 6, 43, 322

Maximum background 

(HCGW-GW14)*

08/25/2010 2.2 0.50 16, pp. 5, 43-51, 58; 17, pp. 5-

7, 37-40, 44-46, 49-50, 54-56

1,1,1-TCA NCIA-GW01 08/24/2010 19 0.50 16, pp. 7, 33, 227

HCGW-GW04 08/24/2010 12 0.50 17, pp. 6, 36, 272

Maximum background 

(NCIA-GW16)*

08/25/2010 1.7 0.50 16, pp. 5, 43-51, 58; 17, pp. 5-

7, 37-40, 44-46, 49-50, 54-56
14

SD- Hazardous Substances (continued)

Source No.: 1

EPA Sampling Event – Ground Water Samples: August 2010 (continued)

Hazardous Substance Sample Number Date 

Sampled

Result 

(μg/L)

RL 

(μg/L)

Reference

TCE NCIA-GW01 08/24/2010 35 0.50 16, pp. 7, 33, 227

NCIA-GW02 08/24/2010 40 J** 10 16, pp. 7, 34, 239, 548; 24, p. 

18

NCIA-GW03 08/24/2010 110 10 16, pp. 7, 36, 251, 556; 24, p. 

18

NCIA-GW07 08/24/2010 17 0.50 14, p. 12; 16, p. 9

HCGW-GW01 08/24/2010 100 10 17, pp. 6, 31, 235, 449; 24, p. 

18

HCGW-GW02 08/24/2010 59 0.50 17, pp. 6, 33, 248

HCGW-GW03 08/24/2010 58 0.50 17, pp. 6, 34, 260

HCGW-GW04 08/24/2010 44 0.50 17, pp. 6, 36, 272

HCGW-GW09 08/24/2010 24 0.50 17, pp. 6, 43, 322

HCGW-GW12 08/24/2010 56 5 17, pp. 7, 48, 351; 24, p. 18

HCGW-GW16 08/24/2010 11 0.50 17, pp. 7, 51, 371

Maximum background 

(HCGW-GW14)*

08/25/2010 2.7 0.50 16, 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-GW04 08/24/2010 0.83 0.50 17, pp. 6, 35, 272

Maximum 

background*

08/24/2010

08/25/2010

ND 0.50 16, 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 08/24/2010 0.77 0.50 17, pp. 6, 31, 235

HCGW-GW02 08/24/2010 0.85 0.50 17, pp. 6, 32, 248

HCGW-GW03 08/24/2010 0.85 0.50 17, pp. 6, 34, 260

HCGW-GW04 08/24/2010 1.2 0.50 17, pp. 6, 35, 272

HCGW-GW08 08/24/2010 0.94 0.50 17, pp. 6, 41, 311

HCGW-GW09 08/24/2010 4.8 0.50 17, pp. 6, 43, 322

HCGW-GW12 08/24/2010 7.9 0.50 17, pp. 7, 47, 351

Maximum 

background*

08/24/2010

08/25/2010

ND 0.50 16, pp. 5, 43-51, 58; 17, pp. 5-

7, 37-40, 44-46, 49-50, 54-56

Vinyl chloride HCGW-GW04 08/24/2010 0.63 0.50 17, pp. 6, 35, 272

Maximum 

background*

08/24/2010

08/25/2010

ND 0.50 16, 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 concern (carbon 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. 16, 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, 363-370, 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., 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]. These results are considered usable because low bias 

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

concentration is three times above unbiased background levels, these release samples would still meet the HRS criteria

(i.e., the true concentrations would still be three times above the background level) [Ref. 29, pp. 5, 8].
15

SD-Hazardous Waste 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 quantity 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 plume height of 0.01 foot, the minimum volume would be 1 million cubic feet, which is 

converted to cubic yards as follows:

1,000,000 ft3 ÷ 27 ft3/yd3 = 37,037.037 yd3

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

51591, Section 2.4.2.1.3, Table 2-5].

Dimension of source (yd3

): 37,037.037 yd3

Volume (V) Assigned Value: (37,037.037)/2.5 = 14,814.814

2.4.2.1.4 Area

The area of observed ground water contamination exceeds 2,200 acres [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 (ft2

): N/A

Area (A) Assigned Value: 0

2.4.2.1.5 Source Hazardous Waste Quantity Value

The source hazardous waste quantity value for Source 1 is 14,814.814 for Tier C - Volume [Ref. 1, p. 51591].

Source Hazardous Waste Quantity Value: 14,814.814
16

SD-Summary

SITE SUMMARY OF SOURCE DESCRIPTIONS

Source Number Source Hazardous 

Waste Quantity 

Value

Containment

Ground Water Surface 

Water

Air (Gas) Air 

(Particulate)

1 14,814.814 10 NS NS NS

NS = Not Scored
17

GW-General

3.0 GROUND WATER MIGRATION PATHWAY

3.0.1 General Considerations

The aquifer being evaluated at the NCHGWC site isthe Magothy aquifer, which is the primary source of drinking water

in Nassau County [Ref. 18, pp. 5-16; 21, pp. 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 from 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 

the Magothy aquifer underlies most of Nassau County, including the NHCGWC site and surroundings, and it is the most 

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 mean sea level (MSL) to 560 feet below MSL [Ref. 30, pp. 1-10]. At the NCHGWC site, the Magothy is overlain 

by the upper glacial aquifer (UGA) from ground surface to a depth of approximately 60-100 ft bgs[Ref. 8, p. 20; 21, p. 5; 

22, pp. 97-98; 30, p. 1]. There are no other hydrogeologic units located between the UGA and Magothy formations[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, pp. 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 glacial aquifer (UGA)

Description: The UGA is an unconfined aquifer consisting of Upper Pleistocene, poorly-sorted sand and gravel deposits, 

from ground surface 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]. The 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 hydrogeologic 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 180-200 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 250-330 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; 30, 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 Magothy 

aquifer [Ref. 18, pp. 5-16; 21, pp. 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 Bowling 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 described below.

3.1.1 Observed Release

Aquifer Being Evaluated: Magothy aquifer

An observed release is documented for the NCHGWC site. Chemical analyses for ground water samples collected from 

several wells in August 2010 show the presence of chlorinated solvents [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, 10-16]. 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, pp. 1-70; 24, pp. 1-28]. 

The CLP SOW and internal laboratory SOP are both based on EPA Method 524.2 purge-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. 29-68; 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 that 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, 571-572; 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), six 

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 collected from background wells showed non-detected (ND) or comparatively low concentrations for 

all contaminants of concern [Figure 1; Ref. 14, pp. 10-16; 15, pp. 10-16; 16, pp. 29-60; 17, pp. 29-58]. Tables 1 and 2

present information and analytical results 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., 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]. These results are considered usable because low bias 

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

concentration is three times above unbiased background levels, these release samples would still meet the HRS criteria

(i.e., the true concentrations 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 collected from the aquifer under 

consideration [Figure 1; Ref. 18, pp. 1-2]. Samples 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; 18, 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; 10-16]. Background and release samples were analyzed within 

the same laboratory batches 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]. The compounds found in the public wells are not naturally occurring, and the nondetected 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 4 

Public Supply Well Sampling - August 2010 New Cassel/Hicksville Ground Water Contamination Site 

Background Concentrations 

Well Name East Meadow 5 East Meadow 3 Roosevelt Field 7 Westbury 6 

Aquifer Magothy Magothy Magothy Magothy 

Screened Interval (ft ±MSL) -420 to -470 -439 to -500 -375 to -503 -170 to -231 

Sample ID NCIA-GW04 NCIA-GW05 NCIA-GW06 NCIA-GW08 

Sample Date 08/24/10 08/24/10 08/24/10 08/25/10 

References 12, p. 4; 14, pp. 5, 12; 

18, pp. 2, 9 

12, p. 4; 14, pp. 5, 12; 

18, pp. 2, 8 

12, pp. 5-6; 14, pp. 5, 

12; 18, pp. 2, 15 

12, p. 11; 14, pp. 5, 

14; 18, pp. 2, 10, 30 

1

VOCs (micrograms per liter [μg/L]) Result RL Result RL Result RL Result RL Carbon tetrachloride 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1-Dichloroethane 0.50 U 0.50 1.1 0.50 1.7 0.50 2.5 0.50 

1,2-Dichloroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1-Dichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 0.50 1.0 0.50 

cis-1,2-Dichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Chloroethane (a.k.a. Ethyl chloride) 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Tetrachloroethene 0.50 U 0.50 1.0 0.50 0.50 U 0.50 0.83 0.50 1,1,1-Trichloroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 1.0 0.50 

Trichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 Trichlorofluoromethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1,2-Trichloro-1,2,2-trifluoroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Vinyl chloride 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

References 16, pp. 7, 37, 263 16, pp. 7, 38-39, 271 16, pp. 7, 40, 280 16, pp. 5, 53-54, 348 

Abbreviations and Acronyms: ft ±MSL - feet above or below mean sea level RL - Reporting limit Data Qualifiers: U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30Notes: Italics indicates the maximum background level 
Table 1 - Background Concentrations, page 2 of 4 

Public Supply Well Sampling - August 2010 New Cassel/Hicksville Ground Water Contamination Site 

Background Concentrations (continued) 

Well Name Westbury 10 Westbury 14 Westbury 15 Westbury 16 

Aquifer Magothy Magothy Magothy Magothy 

Screened Interval (ft ±MSL) -308 to -374 -180 to -270 -370 to -444 -346 to -429 

Sample ID NCIA-GW11 NCIA-GW13 NCIA-GW14 NCIA-GW15 

Sample Date 08/25/10 08/25/10 08/25/10 08/25/10 

References 12, p. 10; 14, pp. 5, 

14; 18, pp. 2, 10, 36 

12, p. 10; 14, pp. 5, 

14; 18, pp. 2, 10, 49 

12, pp. 8-9; 14, pp. 5, 

14; 18, pp. 2, 15, 57 

12, pp. 10-11; 14, pp. 

6, 14; 18, pp. 2, 15, 61 

VOCs (micrograms per liter [μg/L]) Result RL Result RL Result RL Result RL 

Carbon tetrachloride 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1-Dichloroethane 0.59 0.50 1.3 0.50 0.50 U 0.50 0.60 0.50 

1,2-Dichloroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1-Dichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

cis-1,2-Dichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Chloroethane (a.k.a. Ethyl chloride) 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Tetrachloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1,1-Trichloroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Trichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Trichlorofluoromethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1,2-Trichloro-1,2,2-trifluoroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Vinyl chloride 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

References 16, pp. 5, 58, 376 16, pp. 5, 43, 298 16, pp. 5, 44-45, 306 16, pp. 5, 46, 314 1

Abbreviations and Acronyms: ft ±MSL - feet above or below mean sea level RL - Reporting limit Data Qualifiers: U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30Notes: Italics indicates the maximum background level 
Table 1 - Background Concentrations, page 3 of 4 

Public Supply Well Sampling - August 2010 New Cassel/Hicksville Ground Water Contamination Site 

Background Concentrations (continued) 

Well Name Old Westbury 3 Old Westbury 5 Hicksville 6-1R Hicksville 6-2 

Aquifer Magothy Magothy Magothy Magothy 

Screened Interval (ft ±MSL) -222 to -288 -238 to -290 -435 to -465 -230 to -283 

Sample ID NCIA-GW17 NCIA-GW18 HCGW-GW05 HCGW-GW06 

Sample Date 08/25/10 08/25/10 08/24/10 08/24/10 

References 12, p. 12; 14, pp. 6, 

14; 18, pp. 2, 14, 85, 

89 

12, p. 12; 14, pp. 6, 

14; 18, pp. 2, 14, 81 

13, pp. 6-7; 15, pp. 5, 

12; 18, pp. 2, 94-95 

13, pp. 6-7; 15, pp. 5, 

12; 18, pp. 2, 6, 97 

13

VOCs (micrograms per liter [μg/L]) Result RL Result RL Result RL Result RL 

Carbon tetrachloride 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1-Dichloroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.61 0.50 

1,2-Dichloroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1-Dichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

cis-1,2-Dichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Chloroethane (a.k.a. Ethyl chloride) 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Tetrachloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1,1-Trichloroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Trichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 Trichlorofluoromethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1,2-Trichloro-1,2,2-trifluoroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Vinyl chloride 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

References 16, pp. 5, 49, 332 16, pp. 5, 50-51, 340 17, pp. 6, 37, 286 17, pp. 6, 38-39, 294 

Abbreviations and Acronyms: ft ±MSL - feet above or below mean sea level RL - Reporting limit Data Qualifiers: U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30Notes: Italics indicates the maximum background level 
Table 1 - Background Concentrations, page 4 of 4 

Public Supply Well Sampling - August 2010 New Cassel/Hicksville Ground Water Contamination Site 

Background Concentrations (continued) 

Well Name Hicksville 9-1 Hicksville 9-2 Hicksville 10-1 Jericho 9 Jeric

Aquifer Magothy Magothy Magothy Magothy Mag

Screened Interval (ft ±MSL) -389 to -450 -384 to -445 -420 to -498 -305 to -345 -179 t

Sample ID HCGW-GW10 HCGW-GW11 HCGW-GW13 HCGW-GW14 HCGW

Sample Date 08/24/10 08/24/10 08/24/10 08/25/10 08/2

References 13, pp. 5-6; 15, pp. 

5, 12; 18, pp. 2, 13, 

128 

13, p. 6; 15, pp. 5, 

12; 18, pp. 2, 13, 

132 

13, p. 7; 15, pp. 5, 

13; 18, pp. 2, 13, 

146 

13, p. 9; 15, pp. 5, 

15; 18, pp. 2, 7, 170 

13, pp. 9-

5, 15; 18

1

VOCs (micrograms per liter [μg/L]) Result RL Result RL Result RL Result RL Result 

Carbon tetrachloride 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 

1,1-Dichloroethane 1.2 0.50 1.4 0.50 0.50 U 0.50 3.8 0.50 0.79 

1,2-Dichloroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 

1,1-Dichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 1.2 0.50 0.50 U 

cis-1,2-Dichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 

Chloroethane (a.k.a. Ethyl chloride) 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 

Tetrachloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 2.2 0.50 0.50 U 

1,1,1-Trichloroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 1.0 0.50 0.50 U 

Trichloroethene 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 2.7 0.50 0.53 

Trichlorofluoromethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 

1,1,2-Trichloro-1,2,2-trifluoroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 

Vinyl chloride 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 

References 17, pp. 6, 44-45, 333 17, pp. 6, 46, 342 17, pp. 7, 49-50, 363 17, pp. 5, 54, 382 17, pp. 5, 

Abbreviations and Acronyms: ft ±MSL - feet above or below mean sea level RL - Reporting limit Data Qualifiers: U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29-30Notes: Italics indicates the maximum background level 
Table 2 - Observed Release Concentrations, page 1 of 3 

Public Supply Well Sampling - August 2010 New Cassel/Hicksville Ground Water Contamination Site 

Observed Release Sample Concentrations 

Well Name Bowling Green 1 Bowling Green 2 Roosevelt Field 10 

Aquifer Magothy Magothy Magothy 

Screened Interval (ft ±MSL) -350 to -410 -404 to -464 -418 to -504 

Sample ID NCIA-GW01 NCIA-GW02 NCIA-GW03 NCIA-GW07 

Sample Date 08/24/10 08/24/10 08/24/10 08/24/10 

References 12, pp. 6-7; 14, pp. 5, 

12; 18, pp. 2, 14, 19 

12, pp. 6-7; 14, pp. 5, 12; 18, pp. 2, 14, 23 12, p. 6; 14, pp. 5, 12; 

18, pp. 2, 15 

1

5

VOCs (micrograms per liter [μg/L]) Result RL Result RL Result RL Result RL 

Carbon tetrachloride 9.6 0.50 10 0.50 11 0.50 0.50 U 0.50 

1,1-Dichloroethane 6.3 0.50 1.0 0.50 1.0 0.50 0.50 U 0.50 

1,2-Dichloroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1-Dichloroethene 13 0.50 7.7 0.50 8.0 0.50 0.50 U 0.50 

cis-1,2-Dichloroethene 2.2 0.50 6.6 0.50 6.7 0.50 0.50 U 0.50 

Chloroethane (a.k.a. Ethyl chloride) 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Tetrachloroethene 26 0.50 13 J 10 69 10 0.74 0.50 

1,1,1-Trichloroethane 19 0.50 4.1 0.50 4.2 0.50 0.50 U 0.50 

Trichloroethene 35 0.50 40 J 10 110 10 17 0.50 

Trichlorofluoromethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1,2-Trichloro-1,2,2-trifluoroethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Vinyl chloride 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

References 16, pp. 7, 32-33, 227 16, pp. 7, 34, 239, 

548 

16, pp. 7, 35-36, 251, 

556 

16, pp. 7, 41-42, 289 1

Abbreviations and Acronyms: ft ±MSL - feet above or below mean sea level RfD - Reference Dose Screening CoRL - Reporting limit CRSC - Cancer Risk Screening ConcMCL - Maximum Contaminant Level Data Qualifiers: U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29J - The lab used an open vial with headspace for dilution analysis of NCIA-GW02, so PCE and  results (reported from the dilution) are qualified "J" (i.e., the identification of the analyte is acthe reported value is an estimate) and are likely to be biased low [Ref. 16, pp. 29-30, 68, 239, 5Notes:
 

Bold indicates observed release concentrations (i.e., significantly exceed background)
 Shading indicates Level 1 concentrations (significantly exceed background and exceed benchmDashes (---) indicate that the HRS Level I Benchmark is not established
 
Table 2 - Observed Release Concentrations, page 2 of 3 

Public Supply Well Sampling - August 2010 New Cassel/Hicksville Ground Water Contamination Site 

Observed Release Sample Concentrations (continued) 

Well Name Hicksville 4-2 Hicksville 5-2 Hicksville 5-3 

Aquifer Magothy Magothy Magothy 

Screened Interval (ft ±MSL) -400 to -481 -348 to -435 -423 to -489 

Sample ID HCGW-GW04 HCGW-GW01 HCGW-GW02 HCGW-GW03 

Sample Date 08/24/10 08/24/10 08/24/10 08/24/10 

References 13, pp. 7-8; 15, pp. 5, 

12; 18, pp. 2, 13, 124 

13, p. 8; 15, pp. 5, 12; 

18, pp. 2, 6, 114 

13, p. 8; 15, pp. 5, 12; 18, pp. 2, 13, 141 13

VOCs (micrograms per liter [μg/L]) Result RL Result RL Result RL Result RL 

Carbon tetrachloride 8.5 0.50 2.2 0.50 5.9 0.50 5.9 0.50 

1,1-Dichloroethane 38 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,2-Dichloroethane 0.86 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1-Dichloroethene 29 0.50 1.1 0.50 3.6 0.50 3.2 0.50 

cis-1,2-Dichloroethene 23 0.50 3.9 0.50 1.1 0.50 1.1 0.50 

Chloroethane (a.k.a. Ethyl chloride) 1.1 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

Tetrachloroethene 21 0.50 19 0.50 41 0.50 40 0.50 1,1,1-Trichloroethane 12 0.50 1.1 0.50 2.6 0.50 2.6 0.50 

Trichloroethene 44 0.50 100 10 59 0.50 58 0.50 

Trichlorofluoromethane 0.83 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

1,1,2-Trichloro-1,2,2-trifluoroethane 1.2 0.50 0.77 0.50 0.85 0.50 0.85 0.50 

Vinyl chloride 0.63 0.50 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 

References 17, pp. 6, 35-36, 272 17, pp. 6, 31, 235, 

449 

17, pp. 6, 32-33, 248 17, pp. 6, 34, 260 1

Abbreviations and Acronyms: ft ±MSL - feet above or below mean sea level RfD - Reference Dose Screening CoRL - Reporting limit CRSC - Cancer Risk Screening ConcMCL - Maximum Contaminant Level Data Qualifiers: U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29J - The lab used an open vial with headspace for dilution analysis of NCIA-GW02, so PCE and  results (reported from the dilution) are qualified "J" (i.e., the identification of the analyte is acthe reported value is an estimate) and are likely to be biased low [Ref. 16, pp. 29-30, 68, 239, 5Notes:
 

Bold indicates observed release concentrations (i.e., significantly exceed background)
 Shading indicates Level 1 concentrations (significantly exceed background and exceed benchmDashes (---) indicate that the HRS Level I Benchmark is not established
 
Table 2 - Observed Release Concentrations, page 3 of 3 

Public Supply Well Sampling - August 2010 New Cassel/Hicksville Ground Water Contamination Site 

Observed Release Sample Concentrations (concluded) 

HRS Level I 

Benchmarks 

(Drinking Water) 

Well Name Hicksville 8-3 Hicksville 9-3 TOH-Levittown 2A 

Aquifer Magothy Magothy Magothy 

Screened Interval (ft ±MSL) -410 to -495 -432 to -509 -474 to -574 

Sample ID HCGW-GW09 HCGW-GW12 HCGW-GW16 

Sample Date 08/24/10 08/24/10 08/24/10 

References 13, p. 5; 15, pp. 5, 12; 

18, pp. 2, 13, 136 

13, p. 6; 15, pp. 5, 13; 

18, pp. 2, 13, 155 

13, p. 4; 15, pp. 5, 13; 

18, pp. 2, 14 

Ref. 1, p. 51593 

VOCs (micrograms per liter [μg/L]) Result RL Result RL Result RL MCL RfD CRSC 

Carbon tetrachloride 1.8 0.50 0.50 U 0.50 0.50 U 0.50 5 26 0.66 

1,1-Dichloroethane 0.50 U 0.50 1.4 0.50 1.8 0.50 --- 3,700 ---

1,2-Dichloroethane 1.1 0.50 0.50 U 0.50 0.50 U 0.50 5 --- 0.94 

1,1-Dichloroethene 0.50 U 0.50 0.50 U 0.50 2.9 0.50 7 1,800 ---

cis-1,2-Dichloroethene 1.7 0.50 0.73 0.50 3 0.50 70 360 ---

Chloroethane (a.k.a. Ethyl chloride) 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 --- --- ---

Tetrachloroethene 16 0.50 1.3 0.50 1.5 0.50 5 360 1.6 

1,1,1-Trichloroethane 0.50 U 0.50 0.50 U 0.50 1.7 0.50 200 --- ---

Trichloroethene 24 0.50 56 5.0 11 0.50 5 11 0.21 

Trichlorofluoromethane 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 --- 11,000 ---

1,1,2-Trichloro-1,2,2-trifluoroethane 4.8 0.50 7.9 0.50 0.50 U 0.50 --- --- ---

Vinyl chloride 0.50 U 0.50 0.50 U 0.50 0.50 U 0.50 2 110 0.057 

References 17, pp. 6, 43, 322 17, pp. 7, 47-48, 351, 

457 

17, pp. 7, 51, 371 Ref. 2, pp. 11-15, 19 

Abbreviations and Acronyms: ft ±MSL - feet above or below mean sea level RfD - Reference Dose Screening CoRL - Reporting limit CRSC - Cancer Risk Screening ConcMCL - Maximum Contaminant Level Data Qualifiers: U - The analyte was not detected at or above the reporting limit [Ref. 16, pp. 29-30; 17, pp. 29J - The lab used an open vial with headspace for dilution analysis of NCIA-GW02, so PCE and  results (reported from the dilution) are qualified "J" (i.e., the identification of the analyte is acthe reported value is an estimate) and are likely to be biased low [Ref. 16, pp. 29-30, 68, 239, 5Notes:
 

Bold indicates observed release concentrations (i.e., significantly exceed background)
 Shading indicates Level 1 concentrations (significantly exceed background and exceed benchmDashes (---) indicate that the HRS Level I Benchmark is not established
 
27

GW-Observed Release (continued)

Attribution:

EPA has not yet identified 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-detected concentrations in some upgradient public supply wells 

show that they are not ubiquitous throughout the region [Figure 1]. Chlorinated 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 products of PCE and TCE [Ref. 

25, 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 significant efforts to identify the specific source(s) of ground water contamination. For 

instance, in 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 - action 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 developed 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 degreesfrom 1994-1999, including soil and ground water sampling, and 

has since conducted or overseen remedial activities at some 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 the public supply 

wells and has identified contaminated ground water south of the NCIA as a separate operable unit (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 (Wells 5-2 and 5-3). The findings 

indicated 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. 161-1018]. The environmental 

database search indicated that there are 3 Resource Conservation 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 registered 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 the 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. 000075-34-3

1,2-Dichloroethane (DCA) CAS No. 000107-06-2

1,1-Dichloroethylene (1,1-DCE) CAS No. 000075-35-4

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: 550
28

GW-Waste Characteristics

3.2 WASTE CHARACTERISTICS

3.2.1 Toxicity/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 100 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. 19

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. 10

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 complete? (yes/no)

1 14,814.814 No

Sum of Values: 14,814 (rounded to nearest integer as specified in HRS Section 2.4.2.2)

The sum corresponds to a hazardous waste quantity factor value of 10,000 in Table 2-6 of the HRS [Ref. 1, p. 51591]. 

Therefore, a hazardous waste quantity factor value of 10,000 is assigned for the ground water pathway [Ref. 1, pp 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 (10,000): 1 x 108

The product (1 x 108

) 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: 10,000

Waste Characteristics Factor Category Value: 100
29

GW-Targets

3.3 TARGETS

The blended Town of Hempstead water supply system consists of 28 active wells serving 112,592 people, the blended 

Hicksville system consists of 14 active wells serving 47,810 people, and the blended Westbury system consists of 10

active wells serving 20,500 people [Ref. 18, pp. 1, 18, 29, 91]. No single well in any of these systems contributes more 

than 40 percent of the total blended water supply, so each population is apportioned equally among the system 

components (i.e., the active wells) [Ref. 1, p. 51603; 18, pp. 1-2, 18, 29, 91]. 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. 18, pp. 1-2]. The apportioned 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 Contamination**

References

Bowling Green 1 0.72 4,021 Level I Figure 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 Figure 1; 18, pp. 1-2, 91

Hicksville Well 5-2 0.31 3,415 Level I Figure 1; 18, pp. 1-2, 91

Hicksville Well 5-3 0.31 3,415 Level I Figure 1; 18, pp. 1-2, 91

Hicksville Well 8-1 1.86 3,415 Level I Figure 1; 18, pp. 1-2, 91

Hicksville Well 8-3 1.84 3,415 Level I Figure 1; 18, pp. 1-2, 91

Hicksville Well 9-3 2.24 3,415 Level I Figure 1; 18, pp. 1-2, 91

Westbury Well 11 2.11 2,050 Level II 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]. These 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 MCL/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. 19

Freon 11 --- 11,000 --- 2, pp. 14, 18

Vinyl chloride 2 110 0.057 2, p. 15
30

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 0.66 (CRSC)

5 (MCL)

2, p. 9; 16, 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 (MCL)

11 (RfD)

2, p. 15; 16, p. 33

Bowling 

Green Well 2

NCIA-GW02 / 

NCIA-GW03

(field 

duplicates)

Carbon 

tetrachloride

10 / 11 0.66 (CRSC)

5 (MCL)

2, p. 9; 16, pp. 34, 

36

1,1-DCE 7.7 / 8.0 7 (MCL) 2, p. 10; 16, pp. 

34-35

PCE 13 J / 69 1.6 (CRSC)

5 (MCL)

2, p. 11; 16, pp. 

34, 36

TCE 40 J / 110 0.21 (CRSC)

5 (MCL)

11 (RfD)

2, p. 15; 16, pp. 

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 0.66 (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 0.66 (CRSC) 2, p. 11; 17, p. 31

PCE 19 1.6 (CRSC)

5 (MCL)

2, p. 14; 17, p. 31

TCE 100 0.21 (CRSC)

5 (MCL)

11 (RfD)

2, p. 19; 17, p. 31

Hicksville 

Well 5-3

HCGW-GW02 

/ HCGWGW03

(field 

duplicates)

Carbon 

tetrachloride

5.9 / 5.9 0.66 (CRSC)

5 (MCL)

2, p. 11; 17, pp. 

33-34

PCE 41 / 40 1.6 (CRSC)

5 (MCL)

2, p. 14; 17, pp. 

33-34

TCE 59 / 58 0.21 (CRSC)

5 (MCL)

11 (RfD)

2, p. 19; 17, pp. 

33-34
31

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 0.66 (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 cis-1,2-DCE 2.2 70 (MCL) 2, p. 12; 16, p. 32

1,1,1-TCA 19 200 (MCL) 2, p. 14; 16, p. 33

Bowling 

Green Well 2

NCIA-GW02 / 

NCIA-GW03

(field 

duplicates)

cis-1,2-DCE 6.6 / 6.7 70 (MCL) 2, p. 12; 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. 12; 17, p. 36

1,2-DCA 0.86 0.94 (CRSC) 2, p. 12; 17, p. 36

cis-1,2-DCE 23 70 (MCL) 2, p. 12; 17, p. 36

Ethyl chloride 1.1 none established 2, p. 13, 17; 17, p. 35

1,1,1-TCA 12 200 (MCL) 2, p. 14; 17, p. 36

Freon 11 0.83 11,000 (RfD) 2, p. 14, 18; 17, p. 35

CFC-113 1.2 none established 2, pp. 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. 32, 

34

CFC-113 0.85 / 0.85 none established 2, pp. 14-18; 17, pp. 

32, 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; 17, 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. 47
32

GW-Nearest Well/Population

3.3.1 Nearest Well

As identified 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 drinking 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; 18, pp. 1-2, 18

Bowling Green Well 2 4,021 2, p. 9; 16, pp. 34-36; 18, pp. 1-2, 18

Roosevelt Field Well 10 4,021 2, p. 9; 16, p. 42; 18, pp. 1-2, 18

Levittown Well 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, 91

Hicksville Well 5-2 3,415 2, p. 9; 17, p. 31; 18, pp. 1-2, 91

Hicksville Well 5-3 3,415 2, p. 9; 17, pp. 32-34; 18, pp. 1-2, 91

Hicksville Well 8-1 3,415 2, p. 9; 17, p. 42; 18, pp. 1-2, 91

Hicksville Well 8-3 3,415 2, p. 9; 17, p. 43; 18, pp. 1-2, 91

Hicksville Well 9-3 3,415 2, p. 9; 17, p. 48; 18, pp. 1-2, 91

==================================================================================

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 

concentrations. 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; 18, pp. 1-2, 29

==================================================================================

Population Served by Level II Wells: 2,050 Level II Concentrations Factor Value: 2,050

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 

concentrations [Figure 1; Table 1]. However, since 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: NS
33

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, since 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 Section 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 

designation for all public supply wells in the Magothy aquifer [Ref. 33, pp. 15-25]. The public supply wells showing 

observed release concentrations at the NCHGWC site all withdraw water from the Magothy aquifer [Ref. 18, pp. 1-2, 5-

16]. Based on this information, 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