Table 4. Mean normalized concentrations of metals leaching from well casings

Table 3 (cont'd). Concentration (g/L) of metals

Table 4. Mean normalized concentrations of met-

found leaching from well casings.

als leaching from well casings.*

h. Silver

PTFE

LD

0.043

≈1.4

≈1.0

≈1.5

≈1.0

PVC

PTFE

LD

0.010

LD

≈1.8

≈1.0

PTFE

LD

0.059

LD

≈1.2

≈1.0

≈1.2

≈1.7

FEP

X

<0.010

<0.026

<0.021

FRE

>5.7

>2.8

>2.4

>4.3

% RSD

--

FRP

>6.0

>2.4

>2.0

>1.4

COPPER

FEP

0.040

LD

0.014

0.033

FEP

LD

0.079

PVC

0.88

0.76

0.63

0.68

FEP

0.051

LD

PTFE

0.99

0.95

0.97

0.98

X

<0.034

<0.010

<0.011

<0.041

FEP

0.91

0.83

0.84

0.80

% RSD

--

FRE

0.56

0.46

0.42

FRP

0.74

0.62

0.55

0.49

FRE

0.040

0.031

LD

LEAD

FRE

LD

0.025

≈1.0

≈1.4

≈1.2

FRE

0.037

LD

0.060

LD

PVC

≈2.3

≈1.0

X

<0.029

<0.017

<0.027

<0.015

PTFE

>1.5

≈1.1

≈1.0

% RSD

--

FEP

>2.4

>1.8

≈1.2

≈1.0

FRE

FRP

LD

FRP

>34

>29

>22

>28

FRP

LD

0.050

0.018

LD

NICKEL

FRP

LD

≈1.1

X

<0.010

<0.023

<0.013

<0.010

PVC

>1.2

>1.3

1.4

% RSD

--

PTFE

>1.3

>1.4

>1.2

1.1

FEP

>1.8

>1.5

>1.3

1.7

LD Values less than MDL.

FRE

>3.0

>2.2

>2.3

2.1

FRP

>3.4

>2.8

>2.7

2.1

ZINC

ceeded the MCL of 15 g/L set by the US EPA

PVC

2.2

3.48

2.84

3.22

PTFE

1.96

1.74

2.17

1.94

(1994) for drinking water, although the mean val-

FEP

1.78

2.01

1.68

1.63

ues for each day and material were below this

FRE

2.35

3.24

2.28

3.08

limit. For samples exposed to the other materials,

FRP

6.86

11.5

7.34

8.48

concentrations were well below the MCL. Con-

* The mean normalized concentration was determined by

centrations were always less than 2 g/L and gen-

dividing the mean concentration of a given analyte at a given

erally were less than 1 g/L.

time and for a particular casing material by the mean con-

centration (for the same analyte) of the control sample taken

Lead concentrations in the samples exposed to

at the same time.

FRP were much higher than Hewitt (1989) ob-

The mean normalized concentrations for samples where

one or more values for the controls were less than the MDL

served for samples exposed to SS 304 and 316

are marked with >.

under similar conditions. The other materials

In cases where one or more values for the sample are also

(PVC, PTFE, FEP, and FRP) appear to leach less

less than the MDL, the mean normalized concentration is

marked with ≈.

lead than SS 304 and 316 casings did under simi-

lar conditions.

ples (Table 3f). Thus, statistical comparisons with

the control samples could be made only for the

Nickel

Concentrations of Ni in the control samples

40-day samples. Throughout the study, there was

were below the MDL, except for the 40-day sam-

no significant difference between the concentra-

8