United States Office of Water EPA 816-R-99-006
Environmental Protection 4607 DRAFT- April 1999
Agency
<&EPA A Review of Contaminant
Occurrence in Public
Water Systems Related to
Class V Injection Wells
Printed on Recycled Pape
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Table of Contents
List of Tables ii
Acknowledgments iii
Disclaimer iv
I. Introduction 1
II. Methods and Data 1
III. Industries and Contaminants Associated with Class V Wells 4
IV. Contaminant Occurrence 8
Ground water systems 9
Surface water systems 10
Unregulated Contaminant Monitoring Information System 12
Comparison of national cross-section of States and Unregulated Contaminant Monitoring
Information System data 13
V. Discussion and Conclusions 15
APPENDIX A. DATA MANAGEMENT 17
APPENDIX B. INDUSTRIES THAT POTENTIALLY USE CLASS V WELLS 21
APPENDIX C. NATIONAL CROSS-SECTION AND SUPPLEMENTARY DATA TABLES
23
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List of Tables
Table 1. States with water quality data included in the national cross-section of drinking
water occurrence 3
Table 2.a. Contaminants known or suspected to be associated with Class V injection wells:
inorganic compounds 6
Table 2.b. Contaminants known or suspected to be associated with Class V injection wells:
volatile organic compounds 7
Table 3.a. Summary of occurrence of contaminants associated with Class V Disposal Wells
from a national cross-section of public water systems using ground water; ranges
from all States studied 11
Table 3.b. Summary of occurrence of contaminants associated with Class V Disposal Wells
from a national cross-section of public water systems using surface water; ranges
from all States studied 12
Table 4. Summary of occurrence of contaminants associated with Class V Disposal Wells
from the URCIS data set for public water systems using ground water and surface
water 13
Table 5. Comparison of occurrence of contaminants associated with Class V Disposal Wells
from the URCIS data and the national cross-section State data for public water
systems using ground water and surface water 14
Table 6. Principal State and supplemental databases used for analysis in this report 17
Table 7. Characteristic industries which potentially use Class V wells 21
Table 8.a. Summary of occurrence of contaminants associated with Class V injection wells in
Public Water Systems using ground water from a national cross-section of StatesM
Table 8.b. Summary of occurrence of contaminants associated with Class V injection wells in
Public Water Systems using surface water from a national cross-section of State§5
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Acknowledgements
The drinking-water contaminant occurrence data presented in this report were compiled and
analyzed as part of EPA Office of Ground Water and Drinking Water's (OGWDW) ongoing
review of chemical monitoring programs. This effort was directed by Mr. Edwin Thomas of
OGWDW. The Cadmus Group, Inc. served as the prime contractor for this project, supporting
the data collection and analysis.
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Disclaimer
This is a draft for review purposes only and does not constitute U.S. Environmental Protection
Agency Policy. Do not cite or quote. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
This document is designed to provide technical background information for revisions to the Class
V Injection Well program. The document does not, however, substitute for the SDWA or EPA's
regulations nor is this document a regulation itself. Thus, it cannot impose legally-binding
requirements on EPA, States, or the regulated community, and may not apply to a particular
situation based on the circumstances.
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DRAFT: EPA - CLASS VCONTAMINANT OCCURRENCE DATA REPORT; FOR REVIEW AND COMMENT ONLY
A Review of Contaminant Occurrence in Public Water Systems Related to Class V
Injection Wells
I. Introduction
The purpose of this report is to provide an assessment of the occurrence of contaminants
associated with Class V industrial and automotive waste disposal wells in public water systems.
This evaluation is in support of on-going efforts to revise regulations on certain types of Class V
wells (Class VInjection Wells Underground Injection Control Regulations, Revisions; Proposed
Rule, 63 FR 40586-40614, July 29, 1998). The limited information available does not enable
examination of local geographic or temporal patterns, nor can contaminant occurrence be linked
directly to Class V Well locations or discharges. Site incidence reports provide the best source of
this information. This overview of occurrence data demonstrates that contaminants known to be
associated with Class V wells occur nationally in Public Water Systems (PWSs).
II. Methods and Data
The data used for this study were compiled as part of EPA's Office of Ground Water and
Drinking Water's (OGWDW) Chemical Monitoring Reform (CMR) program's analysis of
contaminant occurrence in PWSs. The data sets are composed of a collection of SDWA
Phasell/V contaminant monitoring results volunteered by several States for the CMR effort.
Other data were included in most State data sets, allowing for analysis of various non-Phasell/V
compounds (e.g., lead, silver, and methyl ethyl ketone). The format of the SDWA occurrence
data does not always lend itself readily to the current analysis.1 Despite some limitations, the data
are adequate for a general review of occurrence of most of the selected Class V contaminants.
Particular data quality issues will be noted in the report as needed.
In total, 14 different databases were used for this analysis, including State databases with over 10
million analytical results from over 25,000 PWSs (see Appendix A). In particular, data from eight
States were used to develop a national cross-section of contaminant occurrence. Table 1 lists and
ranks the cross-section States and the pollution potential indicators used in this summary report.
The eight States were selected to provide a balanced national cross-section, based on geographic
coverage, relative rankings for pollution potential (the number of manufacturing facilities per
For instance, the State data are for finished drinking water (post-treatment) rather than raw (untreated)
water samples. Chloroform was originally considered for study in the analysis since it is a potential Class V
contaminant. However, chloroform is also a by-product of chlorine-based water system disinfectants. Because all
of the data analyzed are from finished water samples, it would not be possible to distinguish between detections of
Class V chloroform and chloroform contamination as a disinfection by-product. Thus, chloroform does not appear
in the current analysis.
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DRAFT: EPA - CLASS VCONTAMINANT OCCURRENCE DATA REPORT; FOR REVIEW AND COMMENT ONLY
square mile), and data quality and completeness.2 These States provide geographic representation
from across the U.S., and some representation from all quartiles of the two major pollution
potential indicators. The data from these eight States were used to compute aggregate
occurrence values (i.e., the percentage of water systems that had a detection of contaminant X) as
an approximation of a national sample. While the data from these cross-section States cannot be
stated to be "statistically representative" their distribution should provide an indication of central
tendency. The national cross-section data have been compared with other large national or multi-
State data sets. The comparisons show that the aggregated national cross-section provides a
conservative, but reasonable, approximation of national occurrence values. The comparisons with
other data suggest that the cross-section summary values are likely slightly high.
To ensure sufficient data for analysis, only contaminants which were tested in a significant number
of systems (e.g., several hundred or more) by at least one State included in the CMR analysis,
were selected for inclusion in this study. There may be other contaminants associated with Class
V wells (such as methanol, 1,4-dichlorobenzene, and formaldehyde) which were excluded for lack
of data. Exclusion from this study does not imply that a contaminant does not, in fact, occur in
public water systems — it merely reflects that systems are not testing for this compound, or that
the results are not included in the State's general data set. The compounds selected for analysis
do not include every compound which might conceivably be disposed of through a Class V well.
They are considered to be among the more common Class V related contaminants from the prior
work conducted to review Class V well issues.
9
There is a close correlation between the number of manufacturing establishments per square mile and the
population density in each State, as well as a clear association with the total TRI pounds released/square mile,
number of manufacturing employees, and total value added. Hence, the number of manufacturing establishments
per square mile was used as the best indicator of representativeness. The other key reason for choosing this factor
was that it is a simple measure of how many establishments are actually engaged in manufacturing and thus are
potentially polluting sources of drinking water.
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Table 1. States with water quality data included in the national cross-section of drinking water
occurrence. States are listed by their national rank order (l=highest, 50=lowest) for the number
of manufacturing establishments per square mile.
Quartiles
for rank-
order of
all States
1
2
3
4
National
Cross-
Section
States
New Jersey
Illinois
California
Michigan
Alabama
Oregon
New Mexico
Montana
National Rank:
Number of
Manufacturing
Facilities per
square mile
2
10
11
13
25
34
44
48
J
Additional occurrence data (from Indiana, Iowa, Massachusetts, and the American Water Works
Service Company (AWWSC)) were used to show the range of occurrence in the summaries of
results to provide an estimate of the upper and lower bounds of contaminant occurrence
nationally. However, the ranges for only a few of the contaminants were extended by the
additional data.
Data from EPA's Unregulated Contaminant Monitoring Information System (URCIS) database
were also used as an independent source of data and for a cross-comparison with the State cross-
section analysis. URCIS contains about 3.5 million analytical records from about 40 States and
Territories from the first round of unregulated contaminant monitoring (1989-1993); the database
also includes samples taken prior to 1989 which were grandfathered into the database. (The
URCIS values shown in this report may be different than URCIS values cited in other EPA
reviews because of the screening conducted for this study to ensure consistency in analysis.) The
contaminants in common include all of the volatile organic compounds (VOCs) considered except
for methyl ethyl ketone. URCIS contains no data on inorganic compounds (lOCs).
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III. Industries and Contaminants Associated with Class V Wells
This analysis considers contaminants known or suspected to be associated with effluent from
Class V industrial and automotive waste disposal wells. Conceivably, any retail shop, small
business, or industry which has a septic tank, a floor drain, or some kind of underground drainage
system is a potential Class V well user. Given the variety of potential users, almost any type of
contaminant might be disposed of in a Class V well. Although it is difficult to be certain of the
full list of potential Class V well users and contaminants, studies of State inventories and other
data provide a general overview of some typical Class V well users and the contaminants most
likely to be disposed of through such wells.
Tables 2.a and 2.b present the contaminants known or suspected to be associated with Class V
wells analyzed in this study, broken down into IOC and VOC categories. Also provided in the
tables are the maximum concentration level (MCL) or health advisory level (HAL) of each
contaminant, some common sources and uses for each compound, a general well-type
classification associated with each contaminant, and the potential health effects of contaminant
exposure. The general well-type classification is given as either "A" for automotive waste
disposal users or "I" for industrial waste disposal users. These are meant as very general
associations and it is likely that a contaminant listed only as industrial could on occasion appear in
an automotive waste disposal well. In addition, not every industrial waste disposal well user
would necessarily use all of the contaminants in the industrial category nor would every
automotive waste disposal well user use all of the automotive related contaminants. For a list of
industries which are considered potential Class V well users, see Appendix B or refer to EPA's
OGWDW's Economic Analysis for the Proposed Revisions to the Class V UICRegulations,
1998.
Twenty-three contaminants known or believed to be associated with Class V injection wells were
selected for analysis: arsenic, barium, cadmium, chromium, cyanide, lead, mercury, selenium,
silver, 1,1,1-trichloroethane, 1,1-dichloroethane, 1,2-dichloroethane, benzene, carbon
tetrachloride, chlorobenzene, ethyl benzene, methyl ethyl ketone, methylene chloride,
tetrachloroethylene (PCE), toluene, trichloroethylene (TCE), vinyl chloride, and xylenes (total).
Many of these contaminants are cited in the 1987 Report to Congress on Class VInjection Wells,
the Class V proposed rule (63 FR 40600, July 29, 1998), EPA's Comprehensive Environmental
Response, Compensation, and Liability Information System (CERCLIS) database, or in EPA
Records of Decision (RODs) reports on contamination sites.
Of these 23 contaminants, 1,2-dichloroethane, benzene, chlorobenzene, ethyl benzene, methylene
chloride, PCE, TCE, toluene, xylenes, arsenic, barium, cadmium, chromium, and lead have been
associated with Class V motor vehicle waste disposal wells by EPA in (63 FR 40600, July 29,
1998) or with the automobile service industry, in general. These establishments (and their
corresponding Standard Industrial Classification Code) include general automotive repair shops
(SIC 7538), gasoline service stations (SIC 5541), and motor vehicle dealers (SIC 5511 and 5521).
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Methylene chloride and trichloroethylene may also be associated with carwashes which wash the
undercarriage of vehicles (SIC 7542).
Many industrial waste disposal wells share the same effluent constituents of the automotive waste
disposal wells. In addition to those VOC contaminants listed above, 1,1-dichloroethylene, 1,1,1-
trichloroethane, carbon tetrachloride, methyl ethyl ketone, and vinyl chloride are also associated
with industrial waste disposal wells. Such industries include plastics products (SIC 3089),
commercial printing (SIC 2752 and 2759), petroleum and petroleum product wholesalers (SIC
5172), chemicals and allied products wholesalers (SIC 5169), dry cleaners (SIC 7216), and retail
nursery and garden stores (SIC 5261), among others.
Arsenic, barium, cadmium, chromium, cyanide, lead, mercury, selenium, and silver are inorganic
compounds associated with a variety of industrial processes which may involve discharges into an
industrial waste disposal well. Electric services (SIC 4911), welding repair (SIC 7692),
commercial lithographic printing (SIC 2752), and general contractors (SIC 1521) are some of the
potential sources of one or more of these contaminants in Class V Wells.
Funeral homes (SIC 7261) are associated with formaldehyde, methanol, and phenol in the
proposed regulation. However, there is insufficient data on these compounds to include them in
this report.
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Table 2.a. Contaminants known or suspected to be associated with Class V injection wells:
inorganic compounds.
Contaminant
MCL/
HAL*
(mg/L)
Common Sources and Uses
Potential
Industry
(A = automotive,
I = industrial)
Inorganic Chemicals
Arsenic
Barium
Cadmium
Chromium
Cyanide
Lead
Mercury
Selenium
Silver
0.050
2.0
0.0050
0.10
0.20
0.0150
0.0020
0.050
0.10
Natural deposits, smelters,
glass, electronic wastes, old
orchards
Natural deposits, pigments,
epoxy sealants, spent coal
Galvanized pipe corrosion,
natural deposits, batteries,
paints, electroplating
Natural deposits, mining,
electroplating, pigments
Electroplating, steel, plastics,
mining, fertilizer
Pipes, solder, paint, batteries
Natural deposits, batteries,
electrical switches
Natural deposits, mining,
smelting, coal/oil combustion,
paint manufacture
Photographic procedures,
jewelry making, solders,
electroplating
A, I
A, I
A, I
A, I
I
A, I
I
I
I
Potential Health
Effects
Skin, nervous system toxicity
Circulatory system effects
Kidney effects
Liver, kidney, circulatory
disorders
Thyroid, nervous system
damage
Brain damage, kidney
damage, central nervous
system effects
Kidney, nervous system
disorders
Liver damage
Argyreia (permanent skin
discoloration), kidney effects
* Health advisory level in italics.
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Table 2.b. Contaminants known or suspected to be associated with Class V injection wells:
volatile organic compounds.
Contaminant
MCL/
HAL*
(mg/L)
Common Sources and Uses
Potential
Industry
(A = automotive,
I = industrial)
Volatile Organic Chemicals
Benzene
Carbon tetrachloride
Chlorobenzene
1 ,2-Dichloroethane
1 ,1 -Dichloroethene
(1 ,1 -Dichloroethylene)
Ethyl benzene
Methylene chloride
(Dichloromethane)
Methyl ethyl ketone
Tetrachloroethylene
(PCE)
Toluene
1,1,1 -Trichloroethane
Trichloroethene (TCE)
Vinyl chloride
Xylenes (Total)
0.0050
0.0050
0.10
0.0050
0.0070
0.70
0.0050
—
0.0050
1.0
0.20
0.0050
0.0020
10.0
Gas, drugs, paint, plastics, solvent,
printing and lithography
Solvents and their degradation
products
Waste solvent from metal
degreasing processes
Leaded gas, fumigants, paints,
solvent, gasoline additive
Plastics, dyes, perfumes, paints
Gasoline, insecticides, chemical
manufacturing wastes, solvent
Paint stripper, metal degreaser,
propellant
solvent, manufacturing, cements &
adhesives
Dry cleaning, solvent
Gasoline additive, manufacturing
operations, solvent
Adhesives, aerosols, textiles,
paints, inks, metal degreasers,
drain cleaner, solvent
Textiles, adhesives and metal
degreasers
Plastics industry, may leach from
PVC pipe, solvent breakdown
By-product of gasoline refining,
paints, inks, detergents, solvent
A, I
I
A, I
A, I
I
A, I
A, I
I
A, I
A, I
I
A, I
I
A, I
Potential Health
Effects
Cancer
Cancer
Nervous system
and liver damage
Cancer
Cancer, liver &
kidney effects
Liver, kidney,
nervous system
effects
Cancer
Decreased fetal
birth weight
Cancer
Liver, kidney,
nervous, circulatory
effects
Liver, nervous
system effects
Cancer
Cancer
Liver, kidney,
nervous system
effects
* Health advisory level in italics.
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The industries and compounds cited above are by no means an exhaustive list of potential Class V
disposal well users or contaminants. Rather, the list is intended to illustrate the variety of
potential sources and types of effluent associated with Class V wells.
IV. Contaminant Occurrence
^
The results of the occurrence analysis will be summarized by two major contaminant groups:
lOCs (e.g., arsenic, cyanide, mercury); and VOCs (e.g., 1,1,1-trichloroethane, benzene, methylene
chloride, vinyl chloride). Industrial waste disposal wells and automotive waste disposal wells
share many of the same effluent constituents (for example, both types of well users often use
degreasers or solvents). Therefore, no attempt will be made to differentiate contaminants by well-
type in this analysis.
Tables 3.a and 3.b present summaries of contaminant analytical results for the national cross-
section occurrence data for ground water and surface water systems, respectively. As noted, the
cross-section cannot be stated to be a statistically representative sample, but it does provide an
indication of central tendency and an approximation of a national sample. The values presented in
the tables are the percentage of systems from the national cross-section with contaminant
detections at concentrations greater than the MRL (minimum reporting level), the percentage of
systems with detections greater than half the MCL or HAL, and the percentage of systems with
detections greater than the MCL or HAL. (The MCL or HAL is shown for each contaminant in
Tables 2.a and 2.b.) For perspective, the national cross-section IOC data is typically derived from
7,000 PWSs and 35,000 to 40,000 analyses; most VOC results include data from 12,000 to
13,000 PWSs and approximately 150,000 analyses.
Values for the range of percent detections include the supplementary data from all States.
Contaminant occurrence varies from State to State. While the cross-section provides one national
estimate the ranges provide perspective on the variation among States. For example, Table 3.a
shows that, for TCE, 3.1% of ground water systems in the national cross-section have detections
(>MRL). The range (from 0.6 to 12.8%) shows that one State had only 0.6% ground water
systems with detections while the State with the greatest problems had 12.8% of systems with
detections. The ranges provide other perspectives as well. The cross-section provides an
estimate that 2% of ground water systems have detections of cyanide. Among the States, one
State had 0.8% systems with detections exceeding the MCL (>MCL) while at least one other
State had no systems with detections (0.0% >MRL). (The range for percentage systems with
detections is much greater for lOCs than VOCs. This is because there is a wider range of
methods and reporting limits that may be used for lOCs than VOCs.) Appendix C shows the
number of systems and samples collected for each contaminant from both the national cross-
section States and the combined data sets used to characterize the range of occurrence.
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While ground water contamination is the primary concern for UIC Class V wells, data from PWSs
using surface waters are also included. Many injection wells discharge into shallow ground water.
Shallow ground water can recharge wells, but it may also move laterally to provide the basefiow
for streams and lakes. Hence, contaminants originally discharged into ground water may also
appear in surface waters. Also, the observations from the surface water PWSs include systems
that may use both surface and ground water sources, as well as ground water under the direct
influence of surface water. Hence, these data provide additional insight on the occurrence of the
Class V contaminants in these most vulnerable settings.
Every contaminant selected for analysis with an MCL or an HAL has been detected in ground
water and surface water systems at concentrations greater than the MRL. In ground water
systems, every contaminant with an MCL was detected at concentrations greater than the MCL;
in surface water systems every contaminant, except cyanide, selenium, total xylenes, and methyl
ethyl ketone was detected at levels greater than the MCL. (Note: methyl ethyl ketone does not
have an MCL or HAL.)
Data from testing for the contaminant methyl ethyl ketone was only included in two data sets.
Thus, the values given for methyl ethyl ketone are supplementary and can not be taken as
representative of the state of occurrence nation-wide. However, methyl ethyl ketone was
detected in ground water supplied PWSs. Refer to Appendix C for information on methyl ethyl
ketone occurrence.
Ground water systems
All nine of the lOCs were detected in ground water systems in the cross-section of States at
concentrations greater than the MRL. Cyanide was detected in the lowest percentage of systems
(2.0%) and barium was detected in the highest percentage of systems (47.3%). All of the lOCs
were detected at concentrations greater than the MCL. Silver has the lowest percentage of
systems with detections greater than the MCL (0.1%) and lead has the highest percentage of
systems with detections greater than the MCL (3.1%). (Among the individual States, the range
for the percentage of systems with detections greater than the MCL varied from 0.0% to 0.3% for
silver and from 0.0% to 26.7% for lead.) These findings are not surprising. Barium typically
occurs in greater concentrations naturally and lead is often associated with piping and solder in
older water systems. (From these data the occurrence of lead related to sources within a water
system cannot be separated from contamination that may be related to Class V wells, or other
external sources.)
All of the VOCs were detected in ground water systems in the cross-section of States at
concentrations greater than the MRL. Vinyl chloride was detected in the lowest percentage of
systems (0.5%) and methylene chloride was detected in the highest percentage of systems
(11.1%). All of the VOCs were detected in ground water systems in the cross-section of States at
concentrations greater than their MCL (except for methyl ethyl ketone which has no MCL or
HAL). Ethyl benzene and total xylenes were detected at concentrations greater than the MCL in
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the lowest percentage of systems (0.1%) and methylene chloride was detected greater than the
MCL in the highest percent percentage of systems (2.3%). (Among the individual States, the
range for the percentage of systems with detections greater than the MCL varied from 0.0% to
0.6% for vinyl chloride and from 0.0 to 11.9% for methylene chloride.) It should be noted
however, that the detection of methylene chloride can be confounded with other organic
compounds, and it is suspected that the occurrence values reported may be too great.
Surface water systems
All nine of the lOCs were detected in surface water systems in the cross-section of States at
concentrations greater than the MRL. Cadmium, cyanide, and silver were detected in the lowest
percentage of systems (5.1%) and barium was detected in the highest percentage of systems
(49.1%). All of the lOCs were detected in surface water systems in the cross-section of States at
concentrations greater than the MCL with the exceptions of cyanide and selenium. Cadmium,
chromium, and silver have the lowest positive percent detections greater than the MCL (0.2%)
and lead was detected in the highest percentage of systems at concentrations greater than the
MCL (1.1%). (Among the individual States, the range for the percentage of systems with
detections greater than the MCL varied from 0.0% to 0.5% for chromium and silver and from
0.0% to 11.8% for lead.) Again, it should be noted that some of the lead detections may be
associated with piping and solder within a water system rather than an outside source of
contamination.
Thirteen of the VOCs were detected in surface water systems in the cross-section of States at
concentrations greater than the MRL. The contaminant 1,1-dichloroethane was detected in the
lowest percentage of systems (2.9%) and methylene chloride was detected in the highest
percentage of systems (25.6%). All of the VOCs were detected in surface water systems in the
cross-section of States at concentrations greater than half the MCL and all of the VOCs except
total xylenes were detected in surface water systems in the cross-section of States at
concentrations greater than the MCL. Chlorobenzene has the lowest percent detections greater
than the MCL (0.2%) and methylene chloride was detected in the highest percentage of systems
greater than the MCL (4.7%). (Among the individual States, the range for the percentage of
systems with detections greater than the MCL varied from 0.0% to 3.0% for chlorobenzene and
from 0.0 to 24.2% for methylene chloride.) It should be noted however, that the detection of
methylene chloride can be confounded with other organic compounds, and it is suspected that the
occurrence values reported may be too great.
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Table 3.a. Summary of occurrence of contaminants associated with Class V Disposal Wells from
a national cross-section of public water systems using ground water; ranges from all States
studied.
Ground Water Systems
%>
MRL
Range
>MRL
%>
0.5 MCL*
Range
> 0.5 MCL*
%>
MCL*
Range
>MCL*
Inorganic Compounds
Arsenic
Barium
Cadmium
Chromium
Cyanide
Lead (action level; not MCL)
Mercury
Selenium
Silver
19.3%
47.3%
4.9%
13.2%
2.0%
1 5.4%
4.5%
8.6%
3.5%
2.5% - 95.9%
3 1.5% -98.6%
0.4% - 93.9%
1 .3% - 95.7%
0.0% -9 1.1%
0.0% - 73.3%
0.4% - 93.3%
0.5% - 93.3%
0.3%- 16.7%
1.6%
0.8%
1.2%
0.5%
0.5%
4.8%
0.7%
0.3%
0.3%
0.0% - 4.6%
0.0% - 6.9%
0.0% -2 1.7%
0.0% - 2.4%
0.0%- 1.7%
0.0% - 40.0%
0.0% - 3.2%
0.0% - 0.8%
0.0% - 0.6%
0.9%
0.2%
0.6%
0.2%
0.2%
3.1%
0.4%
0.2%
0.1%
0.0% - 2.5%
'o
0.0%- 1.5%
0.0% - 0.6%
0.0% - 0.8%
0.0% - 26.7%
0.0% - 2.0%
0.0% - 0.5%
0.0% - 0.3%
Volatile Organic Compounds
1.1.1 - Trichloroethane
1.1- Dichloroethene
1 .2 - Dichloroethane
Benzene
Carbon tetrachloride
Chlorobenzene
Ethyl benzene
Methylene chloride (Dichloromethane)
Tetrachloroethylene (PCE)
Toluene
Trichloroethene (TCE)
Vinyl chloride
Xylenes (Total)
3.3%
1.5%
1.4%
1 .2%
1.7%
1 .0%
2.2%
11.1%
4.3%
3.8%
3.1%
0.5%
3.9%
1.1%- 19.4%
0.0% - 5.0%
0.0% - 4.3%
0.0% - 4.2%
0.0% - 8.2%
0.0% - 3.0%
0.5%- 11.2%
0.0% - 57.8%
0.6%- 14.2%
0.0%- 14.4%
0.6%- 12.8%
0.0% - 3.0%
0.4% - 1 5.3%
1.3%
1 .0%
0.6%
0.5%
0.6%
0.3%
0.3%
3.3%
2.3%
0.7%
1.8%
0.2%
0.2%
0.0% - 8.8%
0.0% - 5.0%
0.0% - 2.3%
0.0% - 1 .8%
0.0% - 1 .8%
0.0% - 1 .0%
0.0% - 1 .6%
0.0% - 1 1 .9%
0.1% -7.6%
0.0% - 3.8%
0.0% - 6.2%
0.0% - 0.6%
0.0%- 1.0%
1.3%
0.9%
0.4%
0.4%
0.4%
0.3%
0.1%
2.3%
1.8%
0.4%
1 .5%
0.2%
0.1%
0.0% - 8.4%
0.0% - 5.0%
0.0% - 2.3%
0.0%- 1.8%
0.0% - 1 .8%
0.0% - 1 .0%
0.0% - 0.8%
0.0% - 1 1 .9%
0.0% - 5.7%
0.0% - 2.3%
0.0% - 5.5%
0.0% - 0.6%
0.0% - 0.8%
* % > MCL indicates the proportion of systems with any analytical results exceeding the concentration value of the MCL; it does not necessarily indicate
an MCL violation. An MCL violation occurs when the MCL is exceeded by the average results from four quarterly samples or confirmation samples as
required by the primacy State.
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Table 3.b. Summary of occurrence of contaminants associated with Class V Disposal Wells from
a national cross-section of public water systems using surface water; ranges from all States
studied.
Surface Water Systems
%>
MRL
Range
>MRL
%>
0.5 MCL*
Range
> 0.5 MCL*
%>
MCL*
Range
>MCL*
Inorganic Compounds
Arsenic
Barium
Cadmium
Chromium
Cyanide
Lead (action level; not MCL)
Mercury
Selenium
Silver
13.0%
49.1%
5.1%
10.5%
5.1%
18.3%
9.0%
1 1 .2%
5.1%
0.5%- 100.0%
22.1%- 100.0%
0.0%- 100.0%
0.9%- 100.0%
0.0% - 95.7%
0.0%- 100.0%
0.0%- 100.0%
0.0%- 100.0%
0.0% - 27.3%
0.6%
0.6%
1.3%
0.3%
0.4%
4.6%
1.3%
0.2%
0.2%
0.0% - 3.0%
0.0% -6.1%
0.0% -9.1%
0.0% - 0.9%
0.0% - 3.8%
0.0%- 100.0%
0.0% -6.1%
0.0% - 3.0%
0.0% - 0.5%
0.5%
0.5%
0.2%
0.2%
0.0%
1.1%
0.5%
0.0%
0.2%
0.0% - 3.0%
0.0% - 3.0%
0.0%- 1.9%
0.0% - 0.5%
0.0% - 0.0%
0.0% - 1 1 .8%
0.0%- 1.9%
0.0% - 0.0%
0.0% - 0.5%
Volatile Organic Compounds
1.1.1 - Trichloroethane
1.1- Dichloroethene
1 .2 - Dichloroethane
Benzene
Carbon tetrachloride
Chlorobenzene
Ethyl benzene
Methylene chloride (Dichloromethane)
Tetrachloroethylene (PCE)
Toluene
Trichloroethene (TCE)
Vinyl chloride
Xylenes (Total)
7.3%
2.9%
3.1%
3.9%
9.0%
8.1%
7.3%
25.6%
7.1%
1 1 .9%
5.6%
3.1%
12.3%
0.0% - 20.5%
0.0%- 12.8%
0.0%- 13.7%
0.0%- 17.1%
0.0% - 37.6%
0.0% - 3 1 .6%
0.0%- 17.1%
0.0% - 73.5%
0.0%- 16.2%
0.0% - 30.0%
0.0% -2 1.2%
0.0%- 13.7%
1.9% -29.1%
0.9%
0.3%
0.3%
0.5%
1.6%
0.2%
0.3%
1 0.4%
2.5%
1 .0%
1.9%
0.3%
0.2%
0.0%- 18.2%
0.0% -6.1%
0.0% - 3.7%
0.0% - 3.0%
0.0%- 18.2%
0.0% - 3.0%
0.0% - 3.0%
0.0% - 28.2%
0.0%- 15.2%
0.0% - 7.5%
0.0% -2 1.2%
0.0% - 3.0%
0.0%- 1.9%
0.9%
0.3%
0.3%
0.3%
1.1%
0.2%
0.3%
4.7%
1.7%
0.5%
1.2%
0.3%
0.0%
0.0%- 18.2%
0.0% -6.1%
0.0%- 1.9%
0.0% - 3.0%
0.0%- 18.2%
0.0% - 3.0%
0.0% - 3.0%
0.0% - 24.2%
0.0%- 15.2%
0.0% - 5.7%
0.0% -2 1.2%
0.0% - 3.0%
0.0% - 0.0%
* % > MCL indicates the proportion of systems with any analytical results exceeding the concentration value of the MCL; it does not necessarily indicate
an MCL violation. An MCL violation occurs when the MCL is exceeded by the average results from four quarterly samples or confirmation samples as
required by the primacy State.
Unregulated Contaminant Monitoring Information System
The URCIS database contains information on the following selected contaminants related to Class
V well use: 1,1,1-trichloroethane, 1,1-dichloroethene, 1,2-dichloroethane, benzene, carbon
tetrachloride, chlorobenzene, ethyl benzene, methylene chloride, PCE, toluene, TCE, vinyl
chloride, and total xylenes. Table 4 summarizes the results of the analysis of the URCIS
occurrence data for ground water and surface water systems.
Every contaminant selected for analysis in the URCIS database has been detected in ground water
systems and surface water systems at concentrations greater than the MRL. Every contaminant
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DRAFT: EPA - CLASS VCONTAMINANT OCCURRENCE DATA REPORT; FOR REVIEW AND COMMENT ONLY
was detected at concentrations greater than half the MCL in both ground water systems and
surface water systems with the exception of chlorobenzene, ethyl benzene, toluene, and total
xylenes. In ground water and surface water systems, every contaminant, with the exception of
1,1,1-trichloroethane, chlorobenzene, ethyl benzene, toluene, and total xylenes, was detected at
levels greater than the value of the MCL.
Table 4. Summary of occurrence of contaminants associated with Class V Disposal Wells from
the URCIS data set for public water systems using ground water and surface water.
Ground Water Systems
%>
MRL
%>
0.5 MCL*
%>
MCL*
1 . 1 . 1 -Trichloroethane
1 . 1 -Dichloroethene
1 ,2-Dichloroethane
Benzene
Carbon tetrachloride
Chlorobenzene
Ethyl benzene
Methylene chloride (Dichloromethane)
Tetrachloroethylene (PCE)
Toluene
Trichloroethene (TCE)
Vinyl chloride
Xylenes (Total)
4.5%
1 .4%
1.6%
1 .9%
1.6%
0.3%
1.9%
3.8%
4.2%
3.8%
4.2%
0.5%
3.1%
0.1%
0.5%
0.4%
0.7%
0.5%
0.0%
0.0%
1 .2%
1.9%
0.0%
1.8%
0.3%
0.0%
0.0%
0.3%
0.3%
0.4%
0.3%
0.0%
0.0%
0.7%
1 .2%
0.0%
1.3%
0.2%
0.0%
Surface Water Systems
L%>
MRL
%>
0.5 MCL*
%>
MCL*
5.6%
2.3%
1.8%
2.5%
5.1%
3.4%
4.3%
1 1 .9%
3.1%
8.2%
6.7%
1 .2%
11.9%
0.1%
0.6%
0.5%
0.9%
0.8%
0.0%
0.0%
5.9%
1.2%
0.0%
2.2%
0.8%
0.0%
0.0%
0.3%
0.5%
0.3%
0.4%
0.0%
0.0%
3.3%
0.9%
0.0%
1.3%
0.6%
0.0%
* % > MCL indicates the proportion of systems with any analytical results exceeding the concentration value of the MCL; it does
not necessarily indicate an MCL violation. An MCL violation occurs when the MCL is exceeded by the average results from four
quarterly samples or confirmation samples as required by the primacy State.
Comparison of national cross-section of States and Unregulated Contaminant Monitoring
Information System data
For contaminant occurrence in ground water, the URCIS data and the national cross-section State
data are quite comparable. The similarity between the two different data sets provides some
verification of data quality regarding types and general levels of contaminants. The percentage of
ground water systems with detections greater than the MRL values from the URCIS data are
within one percent of the corresponding national cross-section value with the exception of
methylene chloride (3.8% for URCIS, 11.1% for the cross-section) and TCE (4.2% for URCIS,
3.1 % for the cross-section). Also, every percentage of systems greater than the MRL value from
URCIS falls within the range of values from the State data. All of the percentage of systems
greater than the MCL values from URCIS fall within the range of values from the State data.
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DRAFT: EPA - CLASS VCONTAMINANT OCCURRENCE DATA REPORT; FOR REVIEW AND COMMENT ONLY
For contaminant occurrence in surface water, the URCIS data are also generally consistent with
the cross-section data results, although there is greater variation between the two data sets than is
the case with ground water systems. The percentage of surface water systems with detections
greater than the MRL values from the URCIS data are within two percentage points of the
corresponding national cross-section data for only five of the 11 contaminants (1,1-
dichloroethene, 1,2-dichloroethane, benzene, TCE, vinyl chloride, and total xylenes). However,
only methylene chloride has a difference of greater than five percentage points (11.9% URCIS,
25.6% cross-section) and every percent greater than the MRL value from URCIS falls within the
range of values from the State data. For the percentage of systems with detections at
concentrations greater than the MCL, every value from the URCIS data falls within the range of
values from the State data.
Table 5 illustrates the comparison of percentage of systems with detections greater than the MRL
for URCIS data and the national cross-section State data for ground water and surface water
systems.
Table 5. Comparison of occurrence of contaminants associated with Class V Disposal Wells
from the URCIS data and the national cross-section State data for public water systems using
ground water and surface water.
Ground Water Systems
URCIS
%>
MRL
Cross-
Section
%>
MRL
1 . 1 . 1 -Trichloroethane
1 . 1 -Dichloroethene
1 ,2-Dichloroethane
Benzene
Carbon tetrachloride
Chlorobenzene
Ethyl benzene *
Methylene chloride (Dichloromethane)
Tetrachloroethylene (PCE) f
Toluene
Trichloroethene (TCE)
Vinyl chloride
Xylenes (Total)
4.5%
1.4%
1 .6%
1.9%
1 .6%
0.3%
1 .9%
3.8%
4.2%
3.8%
4.2%
0.5%
3.1%
3.3%
.5%
.4%
.2%
.7%
.0%
2.2%
11.1%
4.3%
3.8%
3.1%
0.5%
3.9%
Surface Water Systems
URCIS
%>
MRL
Cross-
Section
%>
MRL
5.6%
2.3%
1 .8%
2.5%
5.1%
3.4%
4.3%
11.9%
3.1%
8.2%
6.7%
1.2%
1 1 .9%
7.3%
2.9%
3.1%
3.9%
9.0%
8.1%
7.3%
25.6%
7.1%
11.9%
5.6%
3.1%
12.3%
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DRAFT: EPA - CLASS VCONTAMINANT OCCURRENCE DATA REPORT; FOR REVIEW AND COMMENT ONLY
V. Discussion and Conclusions
The results of the analysis show that contaminants associated with Class V wells occur in public
drinking water systems across the nation, many at concentrations greater than their MCL/HAL.
A direct causal link between Class V well effluent and contaminant occurrence in public drinking
water systems can not be established with these data.
J
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J
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APPENDIX A. DATA MANAGEMENT
Table 6. Principal State and supplemental databases used for analysis in this report.
State
Alabama
California
Illinois
Indiana
Iowa
Massachusetts
Michigan (CWS)
Michigan
(NTNC)
Montana
New Jersey
New Mexico
Oregon
STATE
TOTALS
URCIS (40 States
& Territories)
AWWSC(19
States)
TOTALS
Contaminant Groups
Represented (lOCs,
SOCs, VOCs)
IOC, SOC, VOC
IOC, SOC, VOC
IOC, SOC, VOC
IOC, SOC, VOC
IOC, SOC, VOC, O
(published report)
VOCs only
SOC, VOC
SOC, VOC
IOC, SOC, VOC
IOC, SOC, VOC
IOC, SOC, VOC
IOC, SOC, VOC
some SOC, VOC
IOC, SOC, VOC
Number of
Analytical
Results
708,569
3,897,362
2,967,946
257,428
458,320
76,737
346,181
339,540
276,675
980,915
266,262
169,521
10,745,456
3,492,480
55,526
14,293,462
Number of PWSs
with Results
731
6,414
1,392
1,488
2,090
322
1,146
2,106
1,786
4,503
1,299
2,345
25,622
24,357
137
Time Period
1985-1998
1984-1998
1987-1997
1982-1997
1988-1995
1993-1997
1993-1997
1993-1997
1993-1998
1993-1998
1992-1996
1990-1998
1983-1992
1995-1996
Table 6 summarizes the State data utilized and two other major sources of data. Altogether, the
data reviewed for this report include more than 14 million analytical results, not all of which
pertain to Class V related contaminants. (The number of systems from the States and these
supplemental sources is not totaled because there is overlap among these special databases and
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DRAFT: EPA - CLASS VCONTAMINANT OCCURRENCE DATA REPORT; FOR REVIEW AND COMMENT ONLY
some States, and hence many systems would be double-counted.) The supplemental databases
include:
• EPA's Unregulated Contaminant Monitoring Information System (URCIS) with data from
about 40 States and Territories from the first round of unregulated contaminant
monitoring (1989-1993); the data also includes samples taken prior to 1989 which were
grandfathered into the database. (The values shown here for URCIS may be different than
for other EPA reviews because of the screening conducted for this study to ensure
consistency in analysis.)
• Drinking water data from systems operated by the American Water Works Service
Company, which operates systems in many states.
There are numerous data handling and management issues, as well as data quality issues, that had
to be addressed to enable the analysis presented in this report. The primary objective was to
develop a consistent and repeatable approach that would allow data to be compared between and
among the various data sets and allow the data to be jointly evaluated to provide some overview
of occurrence patterns at the national level. A brief review of some of these issues is necessary as
a preface to understanding the results.
In general, States/sources were not asked to reorganize or reformat data, but simply to transmit
the data in whatever manner was easiest. For example, while the Phase II/V compliance data
from 1993-1995 were of the greatest interest, in many cases, it was easier for the State simply to
transmit their entire data set, generally containing information on all chemical contaminants, from
a greater span of years (as noted in Table 5). In addition to the regulated contaminants, every
database included additional data on other contaminants and these varied among each database.
The data were transferred using three main media: FTP, e-mail, and diskettes (including zip-disks
or CD-ROM). Evident from the number of analytical results presented on Table 5, these are very
large databases, often several megabytes in size, and transmission was often complicated. Many
of the data sets received were "as is" and had not been formatted by the State in any way. The
data were received in a number of file types including spreadsheet files, DBF files, and THM files.
Each data set was unique in format, layout, custom codes, and data element usage.
After receiving the data, an initial review of the information was conducted. In most cases, the
data were not accompanied by a protocol outlining each variable. In many cases, the variable
headings could be determined by examination. In every instance, follow-up with the state/data
source was necessary for deciphering variable headings or contaminant codes. When all variables
were understood, a formatting plan for the data was developed. Nearly all of the data sets
required some type of formatting to allow analysis. Data formatting problems varied from one
data set to another.
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DRAFT: EPA - CLASS VCONTAMINANT OCCURRENCE DATA REPORT; FOR REVIEW AND COMMENT ONLY
All statistical analyses were conducted in SAS® statistical software. Data formatting problems
were corrected in Microsoft® Excel with the aid of specialized programs written in Visual Basic®
or were corrected directly in SAS before the analysis began3. Data formatting was the most time
consuming and labor intensive part of the data analysis, often taking many days for each data set.
Each data set presented unique challenges. While analysis of the data was consistent from one
data set to another, each data set required some unique editing and filtering because of differences
in basic data elements.
J
' SAS is a registered trademark of the SAS Institute, Inc.
Excel and Visual Basic are trademarks of the Microsoft Corporation.
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DRAFT: EPA - CLASS VCONTAMINANT OCCURRENCE DATA REPORT; FOR REVIEW AND COMMENT ONLY
J
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DRAFT: EPA - CLASS VCONTAMINANT OCCURRENCE DATA REPORT; FOR REVIEW AND COMMENT ONLY
APPENDIX B. INDUSTRIES THAT POTENTIALLY USE CLASS V WELLS
Table 7. Characteristic industries which potentially use Class V wells
SIC
Code
Description
Industrial Waste Disposal Wells ^J
0742
1521
1541
1611
1711
1794
2752
2759
3089
3599
4911
4953
5012
5013
5063
5082
5083
5084
5085
5087
5169
5172
5261
5411
5551
5941
5983
5999
7261
7389
7542
7692
7694
7699
Veterinary services for animal specialties
General contractors - single family houses
Industrial buildings & warehouses
Highway and street construction (not elevated)
Plumbing, heating and air conditioning
Excavation work
Commercial printing, lithographic
Commercial printing, NEC
Plastics products, NEC
Industrial and commercial machinery & equipment, NEC
Electric services
Refuse systems
Automobiles and other motor vehicles
Motor vehicle supplies and new parts
Electrical apparatus and equipment, wiring supplies & construction materials
Construction and mining (except petroleum) machinery and equipment
Farm & garden machinery and equipment
Industrial machinery and equipment
Industrial supplies
Service establishment equipment
Chemicals and allied products, NEC
Petroleum and petroleum products wholesalers excluding bulk stations and terminals
Retail nurseries and garden stores
Grocery stores
Boat dealers
Sporting goods and bicycle shops
Fuel oil dealers
Miscellaneous retail stores, NEC
Funeral service and crematories
Business services, NEC
Carwashes
Welding repair
Armature rewinding shops
Repair shops and related services, NEC
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DRAFT: EPA - CLASS VCONTAMINANT OCCURRENCE DATA REPORT; FOR REVIEW AND COMMENT ONLY
SIC
Code
Description
Industrial Waste Disposal Wells
7999
8062
8211
8734
9224
Amusement and recreation, NEC
General medical and surgical hospitals
Elementary and secondary schools
Testing laboratories
Fire protection
Motor Vehicle Waste Disposal Wells
4142
4212
4213
4581
5015
5511
5521
5531
5541
7514
7515
7532
7533
7537
7538
7539
7549
9111
Bus charter service, except local
Local trucking, without storage
Trucking, except local
Airports, flying fields, and airport terminal services
Motor vehicle parts, used
Motor vehicle dealers (new and used)
Motor vehicle dealers (used only)
Auto and home supply stores
Gasoline service stations
Passenger car rental
Passenger car leasing
Top, body and upholstery repair shops
and paint shops
Auto exhaust system repair shops
Automotive transmission repair shops
General automotive repair shops
Automotive repair shops, NEC
Automotive services, except repair anc
carwashes
Executive offices
The industries presented in Table 7 are considered illustrative of the variety of sources of potential
Class V well users, and are by no means all-inclusive. For example, dry cleaners (SIC 7216) may
also be included, as noted in the report. These 57 industries are cited in 63 FR 60610, July 29,
1998.
For further details, refer to EPA's Economic Analysis for the Proposed Revisions to the Class V
VIC Regulations, 1998.
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APPENDIX C. NATIONAL CROSS-SECTION AND SUPPLEMENTARY DATA
TABLES
Tables 8.a and 8.b present the national cross-section occurrence data and ranges from Tables 3.a
and 3.b in Section IV of this report. For perspective, the number of analyses and number of
systems testing is included with the percentage of systems with detections. Occurrence values for
methyl ethyl ketone are included at the bottom of both tables. Data from testing for the
contaminant methyl ethyl ketone was only included in two data sets. Even though there are
several thousand analyses, these values given for methyl ethyl ketone are supplementary and ca
not be taken as representative of the state of occurrence nation-wide.
can
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Appendix C
Table 8.a. Summary of Occurrence of Contaminants Associated with Class V Injection Wells in Public Water Systems Using Ground Water
from a National Cross Section of States. Ranges from all States Studied.
Ground Water Systems
Chemical Name
Inorganic Compounds
Arsenic
Barium
Cadmium
Chromium
Cyanide
Lead (action level; not MCL)
Mercury
Selenium
Silver
Volatile Organic Compounds
1,1,1-Trichloroethane
1,1-Dichloroethene
1,2-Dichloroethane
Benzene
Carbon tetrachloride
Chloro benzene
Ethyl benzene
Methylene chloride (Dichloromethane)
Tetrachloroethylene (PCE)
Toluene
Trichloroethene (TCE)
Vinyl chloride
Xylenes (Total)
Methyl Ethyl Ketone
All States
#of
Analyses
39,629
37,856
37,905
37,898
14,978
27,578
37,929
38,065
28,080
149,314
150,962
149,050
147,414
152,076
90,558
144,574
141,887
160,224
144,547
164,806
146,580
142,642
6,149
All States
#of
Systems
8,015
8,037
8,042
8,042
5,324
3,690
8,031
8,008
4,135
15,960
15,950
15,959
15,922
15,948
9,999
15,234
14,522
15,298
15,252
15,951
15,938
15,165
3,051
X Section
#of
Analyses
36,424
34,651
34,702
34,696
12,504
27,364
34,594
34,867
27,866
140,400
142,146
140,218
138,814
143,260
81,749
135,975
132,871
151,307
135,861
155,842
137,766
134,041
2,987
X Section
#of
Systems
6,588
6,609
6,615
6,615
3,984
3,661
6,582
6,581
4,106
12,382
12,380
12,388
12,360
12,379
6,431
11,675
10,939
11,728
11,679
12,380
12,369
11,605
1,058
%>
MRL
19.3%
47.3%
4.9%
13.2%
2.0%
15.4%
4.5%
8.6%
3.5%
3.3%
1.5%
1.4%
1.2%
1.7%
1.0%
2.2%
11.1%
4.3%
3.8%
3.1%
0.5%
3.9%
0.5%
Range > MRL
2.5%
31.5%
0.4%
1.3%
0.0%
0.0%
0.4%
0.5%
0.3%
1.1%
0.0%
0.0%
0.0%
0.0%
0.0%
0.5%
0.0%
0.6%
0.0%
0.6%
0.0%
0.4%
0.0%
-
-
-
-
-
-
-
-
-
-
-
95.9%
98.6%
93.9%
95.7%
91.1%
73.3%
93.3%
93.3%
16.7%
19.4%
5.0%
4.3%
4.2%
8.2%
3.0%
1 1 .2%
57.8%
14.2%
14.4%
12.8%
3.0%
15.3%
0.5%
%>
0.5 MCL*
1.6%
0.8%
1.2%
0.5%
0.5%
4.8%
0.7%
0.3%
0.3%
1.3%
1.0%
0.6%
0.5%
0.6%
0.3%
0.3%
3.3%
2.3%
0.7%
1.8%
0.2%
0.2%
Range > 0.5 MCL*
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.1%
0.0%
0.0%
0.0%
0.0%
-
-
-
-
-
-
-
-
-
-
4.6%
6.9%
21.7%
2.4%
1.7%
40.0%
3.2%
0.8%
0.6%
8.8%
5.0%
2.3%
1.8%
1.8%
1.0%
1.6%
11.9%
7.6%
3.8%
6.2%
0.6%
1.0%
%>
MCL*
0.9%
0.2%
0.6%
0.2%
0.2%
3.1%
0.4%
0.2%
0.1%
1 .3%
0.9%
0.4%
0.4%
0.4%
0.3%
0.1%
2.3%
1.8%
0.4%
1.5%
0.2%
0.1%
Range > MCL*
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-
-
-
-
-
-
-
-
-
-
2.5%
3.1%
1.5%
0.6%
0.8%
26.7%
2.0%
0.5%
0.3%
8.4%
5.0%
2.3%
1.8%
1.8%
1.0%
0.8%
1 1 .9%
5.7%
2.3%
5.5%
0.6%
0.8%
N/A**
* % > MCL indicates the proportion of systems with any analytical results exceeding the concentration value of the MCL; it does not necessar ly indicate an MCL violation. An MCL violation occurs when the MCL is exceeded by the
average results from four quarterly samples or confirmation samples as required by the primacy State.
**N/A: methyl ethyl ketone does not have an MCL or HAL.
-------
Appendix C
Table 8.b. Summary of Occurrence of Contaminants Associated with Class V Injection Wells in Public Water Systems Using Surface Water
from a National Cross Section of States. Ranges from all States Studied.
Surface Water Systems
Chemical Name
Inorganic Compounds
Arsenic
Barium
Cadmium
Chromium
Cyanide
Lead (action level; not MCL)
Mercury
Selenium
Silver
Volatile Organic Compounds
1,1,1-Trichloroethane
1,1-Dichloroethene
1,2-Dichloroethane
Benzene
Carbon tetrachloride
Chlorobenzene
Ethyl benzene
Methylene chloride (Dichloromethane)
Tetrachloroethylene (PCE)
Toluene
Trichloroethene (TCE)
Vinyl chloride
Xylenes (Total)
Methyl Ethyl Ketone
All States
#of
Analyses
4,981
4,796
4,788
4,775
2,143
3,207
4,847
4,775
2,833
12,371
12,613
12,613
12,410
12,432
10,814
11,765
11,560
12,405
11,752
12,925
12,332
11,184
504
All States
#of
Systems
736
732
734
733
566
489
745
734
464
799
801
803
797
800
648
784
732
788
785
801
800
778
67
X Section
#of
Analyses
4,420
4,235
4,226
4,214
1,915
3,019
4,203
4,214
2,645
11,516
11,756
11,753
11,568
11,577
9,960
10,921
10,686
11,550
10,908
12,070
11,478
10,340
485
X Section
#of
Systems
629
625
627
626
452
436
625
627
411
645
646
647
644
645
493
630
577
632
631
646
645
625
59
%>
MRL
13.0%
49.1%
5.1%
10.5%
5.1%
18.3%
9.0%
11.2%
5.1%
7.3%
2.9%
3.1%
3.9%
9.0%
8.1%
7.3%
25.6%
7.1%
11.9%
5.6%
3.1%
12.3%
0.0%
Range > MRL
0.5%
22.1%
0.0%
0.9%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
1.9%
0.0%
-
-
-
-
-
-
-
-
-
-
-
100.0%
100.0%
100.0%
100.0%
95.7%
100.0%
100.0%
100.0%
27.3%
20.5%
12.8%
13.7%
17.1%
37.6%
31.6%
17.1%
73.5%
16.2%
30.0%
21.2%
13.7%
29.1%
0.0%
%>
0.5 MCL*
0.6%
0.6%
1.3%
0.3%
0.4%
4.6%
1.3%
0.2%
0.2%
0.9%
0.3%
0.3%
0.5%
1 .6%
0.2%
0.3%
10.4%
2.5%
1 .0%
1 .9%
0.3%
0.2%
Range > 0.5 MCL*
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-
-
-
-
-
-
-
-
-
-
3.0%
6.1%
9.1%
0.9%
3.8%
100.0%
6.1%
3.0%
0.5%
18.2%
6.1%
3.7%
3.0%
18.2%
3.0%
3.0%
28.2%
15.2%
7.5%
21 .2%
3.0%
1 .9%
%>
MCL*
0.5%
0.5%
0.2%
0.2%
0.0%
1.1%
0.5%
0.0%
0.2%
0.9%
0.3%
0.3%
0.3%
1.1%
0.2%
0.3%
4.7%
1.7%
0.5%
1.2%
0.3%
0.0%
Range > MCL*
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-
-
-
-
-
-
-
-
-
-
3.0%
3.0%
1.9%
0.5%
0.0%
1 1 .8%
1.9%
0.0%
0.5%
18.2%
6.1%
1.9%
3.0%
18.2%
3.0%
3.0%
24.2%
15.2%
5.7%
21 .2%
3.0%
0.0%
N/A**
* % > MCL indicates the proportion of systems with any analytical results exceeding the concentration value of the MCL; it does not necessarily indicate an MCL violation. An MCL violation occurs when the MCL is exceeded
by the average results from four quarterly samples or confirmation samples as required by the primacy State.
**N/A: methyl ethyl ketone does not have an MCL or HAL.
------- |