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HEALTH CONSULTATION

Review of Groundwater Data

SIGMON'S SEPTIC TANK SERVICE FACILITY
(a/k/a SIGMON'S SEPTIC TANK SERVICE)
STATESVILLE, IREDELL COUNTY, NORTH CAROLINA


Table 14.

Drinking Water Comparison Values Table for Sigmon's Septic Tank Service Site
(Summary of Detected Chemical Concentrations found in all Private Wells between 1991 -- 1999)
CHEMICAL SUBSTANCE CHEMICAL CONCENTRATIONS
(ppb)
WATER COMPARISON VALUES
(ppb)
FURTHER PUBLIC HEALTH EVALUATION REQUIRED
Acute EMEGs Intermediate EMEGs
(14 < ___ < 365 days)
Chronic
( > 365 days)
EPA MCL
Detected Concentrations
Non-carcinogenic Carcinogenic
Range Mean Median Adult Child Adult Child Adult Child
INORGANIC MOITIES
Nitrates

100 -- 23,350

8,164

8,600

       

60,000

RMEG

20,000

RMEG

   

10,000

YES
Sulfates1

6,000

6,000

6,000

                   

250,000

NO

METALS

Aluminum

200 -- 1,700

950

950

   

70,000

20,000

37,000

RBC

16,000

RBC

      NO
Barium

16 -- 400

164

90

       

2,000

RMEG

700

RMEG

   

2,000

NO
Calcium

21,000 -- 95,000

58,000

58,000

                      NA
Cobalt

1.2 -- 2.6

2.1

2.4

       

730

RBC

310

RBC

      NO
Copper2

14 -- 60

37.6

38

       

1,500

RBC

630

RBC

   

1,300

NO
Iron1

14 -- 5,500

1,736

195

       

22,000

RBC

9,400

RBC

   

300

YES
Lead2

2 -- 28

8.9

4.5

                   

15

YES
Magnesium

1,600 -- 12,000

6,983

7,250

                      NA
Manganese1

4.2 -- 830

153.1

78

       

2,000

RMEG

500

RMEG

   

50

YES
Mercury5

1 -- 7

2.8

1.6

   

70

20

10

RMEG

3

RMEG

   

2

YES
Nickel

2.3 -- 4.2

3.25

3.25

       

700

RMEG

200

RMEG

      NO
Potassium

1,300 -- 7,000

2,990

2,150

       

2000

 

500

        NA
Sodium3

5,300 -- 15,000

10,150

10,150

                   

20,000

NO
Zinc1

28 -- 2,500

541

155

   

10,000

3,000

10,000

EMEG

3,000

EMEG

   

5,000

NO

ORGANIC COMPOUNDS

Acetone

5 -- 233

71.9

47.5

   

70,000

20,000

10,000

RMEG

3,000

RMEG

      NO
Benzene

0.4

0.4

0.4

       

11

RBC

4

RBC

0.6

CREG

5

NO
Bromodichloromethane4

3

3.0

3.0

1,000

400

   

700

EMEG

200

EMEG

0.6

CREG

80

YES
Chlorobenzene

0.4

0.4

0.4

   

10,000

4,000

700

RMEG

200

RMEG

   

100

NO
Chloroform4

0.6 -- 39

13.46*

0.78*

10,000

3,000

4,000

1,000

400

EMEG

100

EMEG

6

CREG

80

YES
Dibromochloromethane4

1

1

1

1,000

400

   

1,000

EMEG

300

EMEG

0.4

CREG

80

YES
1,2-Dichlorobenzene

0.3 -- 48

24*

24*

       

3,000

RMEG

900

RMEG

   

600

NO
1,4-Dichlorobenzene

0.27 -- 44

3.91*

0.77*

   

10,000

4,000

75

LTHA

   

0.47

RBC

75

YES
1,1-Dichloroethane

0.4 -- 1.5

0.7*

0.6*

       

800

RBC

300

RBC

      NO
1,2-Dichloroethane

0.53

0.53

0.53

   

7,000

2,000

10

RBC

3.6

RBC

0.4

CREG

5

YES
cis-1,2-Dichloroethene

0.43 -- 3.5

1.3*

0.8*

40,000

10,000

10,000

3,000

61

RBC

22

RBC

   

70

NO
Methylene Chloride

2

2

2

7,000

2,000

   

2,000

EMEG

600

EMEG

5

CREG

5

NO
Tetrachloroethene (PCE)

0.29 -- 0.53

0.41*

0.41*

2,000

500

   

400

RMEG

100

RMEG

1.1

RBC

5

NO
Trichloroethene (TCE)

0.27 -- 0.89

0.5*

0.35*

7,000

2,000

   

37

RBC

13

RBC

1.6

RBC

5

NO
Xylenes

0.5 -- 5.1

2.2*

1.6*

   

7,000

2,000

10,000

LTHA

4,500

RBC

   

10,000

NO
Notes:

A chemical is selected for further public health evaluation if the maximum detected chemical level exceeds at least one of its comparison values. Shading indicates the comparison values that are exceeded.

CREG

=

Cancer Risk Evaluation Guide

EMEG

=

Environmental Media Evaluation Guide

LTHA

=

Drinking Water Lifetime Health Advisory

MCL

=

Maximum Contaminant Level

RBC

=

Risk Based Concentration (Note, RBC values derived from equations documented in following reference: EPA Region III Risk-Based Concentration Table. United States Environmental Protection Agency, Region III, 841 Chestnut Street, Philadelphia, PA, 19107. Available on EPA Region IIIís Internet website, http://www.epa.gov/reg3hwmd/risk/ , Background Information - [PDF])

RMEG

=

Reference Dose Media Evaluation Guide

NA

=

None Available

ppb

=

parts per billion

*Average and Median concentrations may be different than displayed in table since some detections were below the quantitation limit for the analyzed chemical (i.e., no value given in inspection/sampling report).

1Listed value in "EPA MCL" column is a Secondary Maximum Contaminant Level (SMCL) for drinking water as set by EPA. SMCLs are unenforceable federal guidelines regarding taste, odor, color, and other non-aesthetic effects of drinking water. EPA recommends them to States as reasonable goals, but federal law does not require water supply systems to comply with them. States may, however, adopt their own enforceable regulations governing these concerns.

2Listed value in "EPA MCL" column is a Maximum Contaminant Level Action (MCLA) for drinking water as set by EPA under Superfund. If the relevant action level is exceeded, a regulatory response is triggered.

3Listed value in "EPA MCL" column is a Drinking Water Equivalent Level (DWEL). The drinking water standard is based on EPA's oral RfD and represent corresponding concentrations of a substance in drinking water that are estimated to have negligible deleterious effects in humans at an intake rate of 2 L/day, assuming that drinking water is the sole source of exposure; however, the listed standard for Sodium is only to be used as a guideline, similar to the Secondary Maximum Contaminant Levels.

4Listed value in "EPA MCL" column is a proposed MCL under the 1994 proposed rule for disinfection by products rule; the current MCL for most trihalomethanes is 100 ppb under the 1996 Drinking Water Advisory Report.

5Listed comparison values for inorganic mercury, except for EPA's MCL, are based on studies of animals administered high doses of mercuric chloride [ATSDR 1999a, NTP 1993, Druet et al. 1978, Bernaudin et al. 1981, Andres 1984].



APPENDIX C: FIGURES

Groundwater Sampling Locations for 1997 Preliminary Assessment / Site Inspection
Figure 1. Groundwater Sampling Locations for 1997 Preliminary Assessment / Site Inspection

Groundwater Sampling Locations for 1999 Expanded Site Inspection
Figure 2. Groundwater Sampling Locations for 1999 Expanded Site Inspection

On-site Monitoring Well Locations in Retrospect to the Former Lagoons
Figure 3. On-site Monitoring Well Locations in Retrospect to the Former Lagoons

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