Water Treatment Technology Feasibility Support Document for Chemical Contaminants for the Second Six-year Review of National Primary Drinking Water Regulations


vvEPA
    United States
    Environmental Protection
    Agency
Water Treatment Technology Feasibility Support
  Document for Chemical Contaminants for the
          Second Six-Year Review of
  National Primary Drinking Water Regulations

-------
Office of Water (4607M)
EPA815-B-09-007
October 2009
www.epa.gov/safewater

-------
EPA-OGWDW           Water Treatment Technology Feasibility Support        EPA 815-B-09-007
                 Document for Chemical Contaminants for the Second Six-Year      October 2009
                    Review of National Primary Drinking Water Regulations
                               Table of Contents
Executive Summary	ES-1
1   Introduction	1-1
2   Measuring Treatment Effectiveness for Contaminants Regulated through MCLs	2-1
3   Treatment Reviews for Contaminants Regulated Through MCLs	3-1
  3.1     2,4-D	3-1
  3.2    Endothall	3-3
  3.3     Hexachlorocyclopentadiene	3-3
  3.4    Oxamyl	3-3
  3.5     Toluene	3-4
  3.6    Xylenes	3-5
  3.7    Benzene	3-5
  3.8     Chlordane	3-6
  3.9    l,2-Dibromo-3-chloropropane(DBCP)	3-6
  3.10   1,2-Dichloropropane	3-7
  3.11   Heptachlor	3-7
  3.12   Heptachlor Epoxide	3-8
  3.13   Hexachlorobenzene	3-8
  3.14   Toxaphene	3-8
  3.15   1,1,2-Trichloroethane	3-9
  3.16   Vinyl Chloride	3-9
  3.17   Carbon Tetrachloride	3-9
  3.18   l,2-Dichloroethane(Ethylene Bichloride)	3-10
  3.19   Bichloromethane	3-10
  3.20   Tetrachloroethylene	3-11
  3.21   Trichloroethylene	3-12
4   Review of Treatment Techniques for Acrylamide and Epichlorohydrin	4-1
  4.1     Improvements in Manufacturing	4-2
  4.2    Regulations and Guidelines in Other Countries	4-2
5   References	5-1
Appendix: Monomer Bata from NSF International	A-l

-------
EPA-OGWDW           Water Treatment Technology Feasibility Support        EPA 815-B-09-007
                 Document for Chemical Contaminants for the Second Six-Year      October 2009
	Review of National Primary Drinking Water Regulations	

                               Table of Exhibits
Exhibit ES-1. Summary of Treatment Feasibility Review for Contaminants Regulated
through MCLs	ES-3
Exhibit 1-1. Contaminants Included in this Treatment Technology Feasibility Review	1-2
Exhibit 3-1. Summary of Treatment Feasibility Review for Contaminants Regulated through
MCLs	3-2
Exhibit 4-1. Summary of NSF International Product Testing Results for Acrylamide and
Epichlorohydrin	4-2
Exhibit 4-2. Comparison of Acrylamide and Epichlorohydrin Drinking Water Guidelines	4-3

-------
EPA-OGWDW
     Water Treatment Technology Feasibility Support
Document for Chemical Contaminants for the Second Six-Year
   Review of National Primary Drinking Water Regulations
EPA815-B-09-007
    October 2009
                     Abbreviations and Acronyms
ANSI            American National Standards Institute
atm m3/m3        atmospheres-cubic meter (of water) per cubic meter (of air)
BAT             Best Available Technology
DBCP            l,2-dibromo-3-chloropropane
EPA             Environmental Protection Agency
EQL             Estimated Quantitation Level
ETV             EPA's Environmental Technology Verification Program
GAC             Granular Activated Carbon
lbs/1,000 gal      pounds of carbon used per 1,000 gallons of water treated
MCL             Maximum Contaminant Level
MCLG           Maximum Contaminant Level Goal
mg/kg            milligrams per kilogram
mg/L             milligrams per liter
NPDWRs         National Primary Drinking Water Regulations
PAC             Powdered Activated Carbon
POU             Point-of-use
POU-GAC        Point-of-use Granular Activated Carbon
PQL             Practical Quantitation Level
PTA             Packed Tower Aeration
SDWA           Safe Drinking Water Act
SOCs            Synthetic Organic Compounds
TCE             Trichloroethylene
TT              Treatment Technique
VOCs            Volatile Organic Compounds
WHO            World Health Organization
ug/L             micrograms per  liter

-------
EPA-OGWDW Water Treatment Technology Feasibility Support EPA 815-B-09-007
Document for Chemical Contaminants for the Second Six-Year October 2009
Review of National Primary Drinking Water Regulations

Executive Summary
The U.S. Environmental Protection Agency (EPA) has completed its second Six-Year Review
(Six-Year Review 2) of national primary drinking water regulations (NPDWRs). The 1996 Safe
Drinking Water Act (SDWA) Amendments require the U.S. Environmental Protection Agency
(EPA or the Agency) to periodically review existing National Primary Drinking Water
Regulations (NPDWRs). Section 1412(b)(9) of SDWA reads:

...[t]he Administrator shall, not less than every 6 years, review and revise, as
appropriate, each primary drinking water regulation promulgated under this title.
Any revision of a national primary drinking water regulation shall be promulgated
in accordance with this section, except that each revision shall maintain, or
provide for greater, protection of the health of persons.

The primary goal of the Six-Year Review process is to identify NPDWRs for possible regulatory
revision. Although the statute does not define when a revision is "appropriate," as a general
benchmark, EPA considered a possible revision to be "appropriate" if, at a minimum, it presents
a meaningful opportunity to:

• improve the level of public health protection, and/or
• achieve cost savings while maintaining or improving the level of public health protection.

For Six-Year Review 2, EPA implemented the protocol that it developed for the first Six-Year
Review (USEPA, 2003), including minor revisions developed during the current review process
(USEPA, 2009d). EPA obtained and evaluated new information that could affect a NPDWR,
including information on health effects (USEPA, 2009f), analytical feasibility (USEPA, 2009b),
and occurrence (USEPA, 2009a and 2009e).

This technical support document provides the Agency's findings for its review of treatment
feasibility information. EPA identified potential to revise NPDWRs for 23 contaminants.
Consequently, EPA reviewed the best available technologies (BATs) and treatment techniques
(TTs) specified in NPDWRs, and any emerging technologies, to determine whether treatment
performance would pose a limitation to such revisions. This document describes these treatment
feasibility reviews.

EPA reviewed the B ATs and technologies to meet TTs to determine the potential to achieve
concentrations based on estimated quantitation levels (EQLs) or new health effects information.
USEPA (2009c) provides a description of the EQLs and USEPA (2009f) identifies the new
health-based thresholds. EPA used these thresholds to evaluate potential for meaningful
opportunity to improve public health protection. The result of the treatment review is a
determination of whether treatment would pose a limitation to revising an NPDWR.

EPA measured technology effectiveness for contaminants for which the enforceable standard is a
maximum contaminant level (MCL) based on the following factors:

• Removal efficiency, which is measured as the percentage of the influent concentration
removed through treatment
ES-1

• Qualitative conclusions about treatability from previous EPA rulemakings and other
scientific and engineering sources
• Other, technology-specific measures.

Aeration and carbon adsorption are common contaminant removal technologies. In instances
when BATs and/or small system compliance technologies include aeration technologies, EPA
used Henry's Law constants as indicators of likely treatment effectiveness. Aeration
technologies, which include packed tower aeration (PTA), multi-stage bubble aeration, tray
aeration, shallow tray aeration, spray aeration, and mechanical aeration, remove contaminants by
passing air through the water to be treated. Aeration processes transfer, or "strip," volatile
contaminants from the water into the air. Henry's Law constants, which can vary across
contaminants, provide measures of the ease with which this stripping occurs.

In instances when BATs and/or small system compliance technologies include carbon adsorption
technologies, EPA used bed life and carbon usage rates as indicators of likely treatment
effectiveness. Carbon adsorption technologies, which include granular activated carbon (GAC),
powdered activated carbon (PAC), and point-of-use granular activated carbon (POU-GAC),
remove contaminants through adsorption onto a carbon media. The length of time for which the
carbon retains its capacity to absorb target contaminants provides a measure of treatment
feasibility and effectiveness.

EPA did not identify limitations of BAT, small system compliance technologies, or emerging
technologies to achieve the EQL or health-based thresholds for most of the contaminants
regulated through MCLs. Exhibit ES-1 summarizes these results. For oxamyl, however, data on
removal efficiency and a lack of demonstrated treatment effectiveness at low concentrations
suggest potential for limitation at concentrations as low as the health-based threshold. Similarly,
for 1,2-dichloropropane, treatment to the estimated quantitation level may not be feasible.

EPA established a TT in lieu of an MCL for acrylamide and epichlorohydrin because of the
absence of standardized analytical methods for measurement in water. The TT limits the
allowable monomer level in products used for water treatment and the dosage of polymers that
contain them. EPA established the residual monomer level for each contaminant at the lowest
level manufacturers could feasibly achieve at the time of regulation. A system can use third-party
or manufacturer's certification in lieu of testing for the residual monomer level.

NSF International (NSF), a third party organization, tests and certifies water treatment chemicals
that meet NSF/ANSI Standard 60, Drinking Water Treatment Chemicals - Health Effects, which
sets out requirements for treatment chemicals based on human health protection (NSF, 1999a).
The requirements for acrylamide- and epichlorohydrin-based polymers in Standard 60 are based
on EPA's TT standards. Thus, NSF 60 certification of a polymeric coagulant aid containing
acrylamide or epichlorohydrin indicates that users are in compliance with EPA's regulation when
a product is used as specified (i.e., for the intended purpose and up to the maximum usage level
indicated by NSF). EPA obtained NSF data indicating that manufacturers now produce polymers
with substantially lower residual monomer content than the TTs require. This new information,
viewed in conjunction with regulations and guidelines in other countries, suggests there is
potential to revise the TTs to reflect a lower feasible monomer content
ES-2

Exhibit ES-1. Summary of Treatment Feasibility Review for Contaminants
Regulated through MCLs
Contaminant
2,4-D
Endothall
Hexachlorocyclopentadiene
Oxamyl
Toluene
Xylenes
Benzene
Chlordane
DBCP
1,2-dichloropropane
Heptachlor
Heptachlor epoxide
Hexachlorobenzene
Toxaphene
1,1,2-trichloroethane
Vinyl chloride
Carbon tetrachloride
1,2-dichloroethane
(ethylene dichloride)
Dichloromethane
Tetrachloroethylene
Trichloroethylene
Current MCL
(mg/L)
0.07
0.1
0.05
0.2
1.0
10.0
0.005
0.002
0.0002
0.005
0.0004
0.0002
0.001
0.003
0.005
0.002
0.005
0.005
0.005
0.005
0.005
Threshold
Evaluated
(mg/L)
0.04
0.05
0.04
0.002
0.6
1.0
0.0005
0.001
0.0001
0.0005
0.0001
0.0001
0.0001
0.001
0.003
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
BAT
GAG1
GAG1
GAG and PTA2
GAG1'3
GAG and PTA4
GAG and PTA4
GAG and PTA3'4
GAG1
GAG and PTA5
GAG and PTA4
GAG1
GAG1
GAG1
GAG1
GAG and PTA4
PTA4
GAG and PTA4
GAG and PTA4
PTA4
GAG and PTA4
GAG and PTA6
Treatment
Limitation
Potential
No
No
No
Uncertain
No
No
No
No
No
Uncertain
No
No
No
No
No
No
No
No
No
No
No
1. Small system compliance technologies are: GAC, PAC, and POU-GAC.
2. Small system compliance technologies are: GAC, POU-GAC, PTA, diffused aeration, multi-stage bubble aeration, tray
aeration, and shallow tray aeration.
3. Although not currently listed as BAT, promising emerging technologies include: RO, RO followed by GAC, and advanced
oxidation (ultraviolet light combined with ozone) followed by GAC.
4. Small system compliance technologies are: GAC, PTA, diffused aeration, multi-stage bubble aeration, tray aeration, and
shallow tray aeration.
5. Small system compliance technologies are: GAC, PAC, PTA, diffused aeration, multi-stage bubble aeration, tray aeration,
and shallow tray aeration.
6. Small system compliance technologies are: GAC, PTA, diffused aeration, multi-stage bubble aeration, tray aeration,
shallow tray aeration, spray aeration, and mechanical aeration.
BAT = best available technologies
DBCP = 1,2-dibromo-3-chloropropane
GAC = granular activated carbon
MCL = maximum contaminant level
Mg/L = milligrams per liter
PAC = powdered activated carbon
POU = point-of-use
PTA = packed tower aeration
RO = reverse osmosis
ES-3

-------
EPA-OGWDW           Water Treatment Technology Feasibility Support        EPA 815-B-09-007
                 Document for Chemical Contaminants for the Second Six-Year      October 2009
	Review of National Primary Drinking Water Regulations	

1   Introduction

The U.S. Environmental Protection Agency (EPA) has completed its second Six-Year Review
(Six-Year Review 2) of national primary drinking water regulations (NPDWRs). The 1996 Safe
Drinking Water Act (SDWA) Amendments require the U.S. Environmental Protection Agency
(EPA or the Agency) to periodically review existing National Primary Drinking Water
Regulations (NPDWRs). Section 1412(b)(9) of SDWA reads:

        ...[t]he Administrator shall, not less than every 6 years, review and revise, as
       appropriate, each primary drinking water regulation promulgated under this title.
       Any revision of a national primary drinking water regulation shall be promulgated
       in accordance with this section, except that each revision shall maintain, or
       provide for greater, protection of the health of persons.

The primary goal of the Six-Year Review process is to identify NPDWRs for possible regulatory
revision. Although the statute does not define when a revision is "appropriate," as a general
benchmark, EPA considered a possible revision to be "appropriate" if, at a minimum, it presents
a meaningful opportunity to:

•   improve the level of public health protection, and/or
•   achieve cost savings while maintaining or improving the level of public health protection.

For Six-Year Review 2, EPA implemented the protocol that it developed for the first Six-Year
Review (USEPA, 2003), including minor revisions developed during the current review process
(USEPA, 2009d). EPA obtained and evaluated new information that could affect a NPDWR,
including information on health effects (USEPA, 2009f), analytical feasibility (USEPA, 2009b),
and occurrence (USEPA, 2009a and 2009e).

This technical  support document provides the Agency's findings for its review of  treatment
feasibility information. EPA identified potential to revise NPDWRs for 23 contaminants.
Consequently,  EPA reviewed the best available technologies (BATs) and treatment techniques
(TTs) specified in NPDWRs, and any emerging technologies, to determine whether treatment
performance would pose a limitation to such revisions. This document describes these treatment
feasibility reviews.

EPA reviewed treatment feasibility for contaminants regulated through MCLs for  which there is
potential to revise the MCL due to:

•   New health effects assessments suggesting potential for a lower MCLG and potential to set
    the MCL equal to a lower MCLG is not limited by practical quantitation levels (PQLs)
•   Analytical  methods review findings indicating the potential for lower PQLs
•   A health effects assessment is ongoing, but the MCLG is less than the MCL and there is
    potential to lower the PQL, which originally limited the MCL
                                          1-1

-------
EPA-OGWDW           Water Treatment Technology Feasibility Support        EPA 815-B-09-007
                 Document for Chemical Contaminants for the Second Six-Year      October 2009
	Review of National Primary Drinking Water Regulations	

EPA also reviewed the treatment feasibility for two contaminants that are regulated through TTs
and are not the subjects of recent or ongoing regulatory action. Exhibit 1-1 identifies the
contaminants included in the review.

    Exhibit 1-1. Contaminants Included in this Treatment Technology Feasibility
                                       Review
             Contaminants regulated through MCLs and potential to revise the MCL
  New health effects assessment indicates potential MCLG decrease, PQL does not currently limit
                        the MCL or there is potential to decrease PQL
1
2
3
4
5
6
2,4-D
Endothall
Hexachlorocyclopentadiene
Oxamyl
Toluene
Xylenes
   New health effects assessment, MCLG = 0, MCL = PQL and there is potential to decrease PQL
  7   Benzene
       No new health effects assessment, MCL = PQL and there is potential to decrease PQL
8
9
10
11
12
13
14
15
16
Chlordane
1 ,2-Dibromo-3-chloropropane (DBCP)
1,2-Dichloropropane
Heptachlor
Heptachlor epoxide
Hexachlorobenzene
Toxaphene
1,1,2-Trichloroethane
Vinyl chloride
     Ongoing health effects assessment, MCL > MCLG and there is potential to decrease PQL
17
18
19
20
21
Carbon tetrachloride
1,2-Dichloroethane (Ethylene Dichloride)
Dichloromethane
Tetrachloroethylene
Trichloroethylene
               Contaminants regulated through TTs and potential to revise the TT
  22
Acrylamide
  23  | Epichlorohydrin
This document primarily discusses best available technologies (BATs) specified by EPA to meet
MCLs and technologies to meet TT-type NPDWRs. It provides supplemental information on
small systems compliance technologies and other related treatment information. EPA relies on
available scientific and engineering data to support this process. The purpose of this report is to
document EPA's evaluation of the potential for BATs to remove contaminants to achieve
concentrations comparable to the estimated quantitation level (EQL) or health-based threshold
for each contaminant. USEPA (2009c) provides a description of how EPA developed the EQLs
or health-based thresholds. EPA used these thresholds to evaluate potential occurrence and
exposure effects in addition to treatment feasibility. The end result of each of the following
                                          1-2

-------
EPA-OGWDW           Water Treatment Technology Feasibility Support        EPA 815-B-09-007
                  Document for Chemical Contaminants for the Second Six-Year       October 2009
	Review of National Primary Drinking Water Regulations	

contaminant-specific reviews is a determination of whether treatment would pose a limitation to
revising an NPDWR.

Section 2 provides background information on the methods the Agency used to evaluate the
effectiveness of treatment technologies for contaminants regulated through MCLs. Section 3
presents the treatment reviews for individual contaminants regulated through MCLs. Finally,
section 4 provides a review of the potential to revise TTs for two contaminants (acrylamide and
epichlorohydrin) regulated through this method.
                                           1-3

-------
EPA-OGWDW           Water Treatment Technology Feasibility Support        EPA 815-B-09-007
                 Document for Chemical Contaminants for the Second Six-Year      October 2009
	Review of National Primary Drinking Water Regulations	

2  Measuring Treatment Effectiveness  for Contaminants
    Regulated through MCLs

As discussed above, the treatment analysis in this document uses treatment benchmarks for the
contaminants that are based on either an EQL or a health-based threshold, which were developed
for the Six-Year Review 2 occurrence analysis (USEPA, 2009c). EPA evaluated technology
effectiveness against this benchmark based on the following factors:

•  Removal efficiency, which is measured as the percentage of the influent concentration
   removed through treatment
•  Qualitative conclusions about treatability from previous EPA rulemakings and other
   scientific and engineering sources
•  Other, technology-specific measures, discussed in more detail below.

Aeration and carbon adsorption are the most common technologies used for the removal of the
contaminants with MCLs in this document. The following discussion describes technology-
specific measures that EPA used in evaluating treatment effectiveness for these technologies.

In instances when BATs and/or small system compliance technologies include aeration
technologies, EPA uses the Henry's Law constant as an indicator of likely treatment
effectiveness. Aeration technologies, which include packed tower aeration (PTA), multi-stage
bubble aeration, tray aeration, shallow tray aeration, spray aeration, and mechanical aeration,
remove contaminants by passing air through the water to be treated. This process transfers, or
"strips," volatile contaminants from the water into the air. The Henry's Law constant provides a
measure of the ease with which this stripping occurs. The units for the Henry's Law constant in
this document are atmospheres-cubic meter (of water) per cubic meter (of air) (atm mVm3); a
higher Henry's Law constant indicates greater strippability, and easier contaminant removal  by
aeration.

In instances when BATs and/or small system compliance technologies include carbon adsorption
technologies, EPA uses bed life and carbon usage rates  as indicators of likely treatment
effectiveness. The use of these indicators is a refinement of the method EPA previously used to
assess treatment technology feasibility during First Six-Year Review. Carbon adsorption
technologies, which include granular activated carbon (GAC), powdered activated carbon
(PAC), and point-of-use granular activated carbon (POU-GAC), remove contaminants through
adsorption onto a carbon media. In GAC and POU-GAC, water to be treated passes through  a
fixed bed of the media; in PAC, the media is mixed into the water to be  treated. In either case,
the media has a specific capacity for adsorbing  a given contaminant. In GAC and POU-GAC,
once this capacity is exhausted, the media must be removed and regenerated or replaced with
fresh media. In PAC, this capacity influences the quantity, or "dose," of powdered carbon
required to remove the contaminant. In either case, the length of time for which the carbon
retains its capacity to absorb target contaminants provides a measure of treatment feasibility  and
effectiveness. For example, a GAC medium will be more useful for a contaminant that it can
continue to remove for several  months than for  a contaminant that exhausts its  capacity quickly.
With GAC treatment, this length of time is typically called "bed life," and can be measured in
                                         2-1

-------
EPA-OGWDW           Water Treatment Technology Feasibility Support        EPA 815-B-09-007
                  Document for Chemical Contaminants for the Second Six-Year      October 2009
	Review of National Primary Drinking Water Regulations	

months, or in the volume of water treated, called "bed volumes." Another measure of carbon
capacity is carbon usage rate, with units of pounds of carbon used per 1,000 gallons of water
treated (lbs/1,000 gal). A lower carbon usage rate reflects a greater capacity for the contaminant,
and more efficient treatment.
                                           2-2

3 Treatment Reviews for Contaminants Regulated Through
MCLs

The results of EPA's review of health effects or analytical feasibility indicated the potential to
revise the NPDWRs for each of the contaminants in this section. Consequently, EPA reviewed
treatment feasibility for each to determine whether treatment feasibility would limit the potential
to revise. Each treatment review includes the following:

• The current MCL for the contaminant and the EQL or health-based threshold developed
during Six-Year Review 2
• Identification of current BATs and small system compliance technologies
• Where appropriate, identification of new or emerging treatment technologies
• Available information on the treatment effectiveness of these technologies for the
contaminant
• Discussion of whether treatment is known to be a limiting concern under the current
NPDWR
• A conclusion regarding whether treatment would be expected to be a limiting concern should
the Agency revise the NPDWR.

Based on the treatment reviews, EPA did not identify limitations of BAT, small system
compliance technologies, or emerging technologies to achieve the EQL or health-based
thresholds for most of the contaminants regulated through MCLs. However, for oxamyl, data on
removal efficiency and a lack of demonstrated treatment effectiveness at low concentrations
suggest potential for limitation at concentrations as low as the health-based threshold. Similarly,
for 1,2-dichloropropane, treatment to the estimated quantitation level may not be feasible.
Exhibit 3-1 summarizes these results.

3.1 2,4-D
The current MCL for 2,4-D is 0.07 mg/L and the current BAT is GAC (40 CFR 141.61). Small
system compliance technologies include: GAC, PAC, and POU-GAC (USEPA, 1998). The
health-based threshold used for the Six-Year Review 2 is 0.04 mg/L (USEPA, 2009f).

According to the World Health Organization (WHO), the achievable GAC removal efficiency
for 2,4-D is more than 80%, to concentrations lower than 0.0001 mg/L (WHO, 2006). Carbon
usage rates for 2,4-D (0.1224 lbs/1,000 gal) are relatively low compared with other organic
contaminants, indicating good treatment feasibility (56 FR 3526, January 30, 1991).

Treatment is not known to be a limiting concern for the current MCL for 2,4-D. The Agency's
current assessment is that treatment technology would not pose a feasibility limitation at the
health-based threshold of 0.04 mg/L.
3-1

-------
EPA-OGWDW
Water Treatment Technology Feasibility Support
Document for Chemical Contaminants for the Second Six-Year
Review of National Primary Drinking Water Regulations
EPA815-B-09-007
October 2009
Exhibit 3-1. Summary of Treatment Feasibility Review for Contaminants
Regulated through MCLs
Contaminant
2,4-D
Endothall
Hexachlorocyclopentadiene
Oxamyl
Toluene
Xylenes
Benzene
Chlordane
DBCP
1,2-dichloropropane
Heptachlor
Heptachlor epoxide
Hexachlorobenzene
Toxaphene
1,1,2-trichloroethane
Vinyl chloride
Carbon tetrachloride
1,2-dichloroethane
(ethylene dichloride)
Dichloromethane
Tetrachloroethylene
Trichloroethylene
Current MCL
(mg/L)
0.07
0.1
0.05
0.2
1.0
10.0
0.005
0.002
0.0002
0.005
0.0004
0.0002
0.001
0.003
0.005
0.002
0.005
0.005
0.005
0.005
0.005
Threshold
Evaluated
(mg/L)
0.04
0.05
0.04
0.002
0.6
1.0
0.0005
0.001
0.0001
0.0005
0.0001
0.0001
0.0001
0.001
0.003
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
BAT
GAG1
GAG1
GAG and PTA2
GAG1'3
GAG and PTA4
GAG and PTA4
GAG and PTA3'4
GAG1
GAG and PTA5
GAG and PTA4
GAG1
GAG1
GAG1
GAG1
GAG and PTA4
PTA4
GAG and PTA4
GAG and PTA4
PTA4
GAG and PTA4
GAG and PTA6
Treatment
Limitation
Potential
No
No
No
Uncertain
No
No
No
No
No
Uncertain
No
No
No
No
No
No
No
No
No
No
No
1. Small system compliance technologies are: GAC, PAC, and POU-GAC.
2. Small system compliance technologies are: GAC, POU-GAC, PTA, diffused aeration, multi-stage bubble aeration, tray
aeration, and shallow tray aeration.
3. Although not currently listed as BAT, promising emerging technologies include: RO, RO followed by GAC, and advanced
oxidation (ultraviolet light combined with ozone) followed by GAC.
4. Small system compliance technologies are: GAC, PTA, diffused aeration, multi-stage bubble aeration, tray aeration, and
shallow tray aeration.
5. Small system compliance technologies are: GAC, PAC, PTA, diffused aeration, multi-stage bubble aeration, tray aeration,
and shallow tray aeration.
6. Small system compliance technologies are: GAC, PTA, diffused aeration, multi-stage bubble aeration, tray aeration,
shallow tray aeration, spray aeration, and mechanical aeration.
BAT = best available technologies
DBCP = 1,2-dibromo-3-chloropropane
GAC = granular activated carbon
MCL = maximum contaminant level
Mg/L = milligrams per liter
PAC = powdered activated carbon
POU = point-of-use
PTA = packed tower aeration
RO = reverse osmosis
3-2

3.2 Endothall
The current MCL for endothall is 0.1 mg/L and the current BAT is GAC (40 CFR 141.61). Small
system compliance technologies include: GAC, PAC, and POU-GAC (USEPA, 1998). The
health-based threshold used for the Six-Year Review 2 is 0.05 mg/L (USEPA, 2009f).

In proposing GAC as the BAT for endothall, EPA concluded that GAC is effective in removing
synthetic organic compounds (SOCs) including endothall (55 FR 30370, July 25, 1990), based
on model predictions that took into account endothall's chemical/physical characteristics.
Subsequent treatability studies in support of the final EPA rulemaking demonstrated that GAC
was as effective as predicted by the model (57 FR 31776, July 17, 1992).

Treatment is not known to be a limiting concern for the current MCL for endothall. The
Agency's current assessment is that treatment technology would not pose a feasibility limitation
at the health-based threshold of 0.05 mg/L.

3.3 Hexachlorocyclopentadiene
The current MCL for hexachlorocyclopentadiene is 0.05 mg/L and the current BATs are GAC
and PTA (40 CFR 141.61). Small system compliance technologies include: GAC, POU-GAC,
PTA, diffused aeration, multi-stage bubble aeration, tray aeration, and shallow tray aeration
(USEPA, 1998). The health-based threshold used for the Six-Year Review 2 is 0.04 mg/L
(USEPA, 2009f).

EPA has categorized hexachlorocyclopentadiene among the more volatile SOCs (55 FR 30370,
July 25, 1990). For the volatile SOCs, properly designed PTA facilities can achieve removal
efficiencies of 90% to more than 99% (55 FR 30370, July 25, 1990). For
hexachlorocyclopentadiene, Henry's Law constants reported in several sources are high, ranging
from 0.6701 to 1.105 atm mVm3, indicating good treatment feasibility (Sander, 1999). EPA has
concluded that GAC also is effective in removing SOCs including hexachlorocyclopentadiene
(55 FR 30370, July 25, 1990).

Treatment is not known to be a limiting concern for the current MCL for
hexachlorocyclopentadiene. The Agency's current assessment is that treatment technology would
not pose a feasibility limitation at the health-based threshold of 0.04 mg/L.

3.4 Oxamyl
The current MCL for oxamyl is 0.2 mg/L and the current BAT is GAC (40 CFR 141.61). The
health-based threshold used for the Six-Year Review 2 is 0.002 mg/L (USEPA, 2009f). Small
system compliance technologies include: GAC, PAC, and POU-GAC (USEPA, 1998). In
addition, EPA's Environmental Technology Verification (ETV) Program recently verified the
performance of several POU devices for removal of chemical contaminants including oxamyl.
The emerging technologies tested in the ETV verifications included reverse osmosis, reverse
osmosis followed by GAC, and advanced oxidation (ultraviolet light combined with ozone)
followed by GAC (NSF, 2005a, 2005b, 2005c, 2006, 2007a).
3-3

GAC removal efficiency for oxamyl ranges from 85% to 95%, depending on design parameters
(USEPA, 1990). The ETV test of a POU device using advanced oxidation followed by GAC
verified that the GAC filter component of the device removed greater than 98% of oxamyl from
an influent concentration of 1.1 mg/L (NSF, 2005c).

The ETV tests of POU devices using reverse osmosis verified that the reverse osmosis
components of these devices removed 99% or more of oxamyl from influent concentrations of
0.98 to 1.1 mg/L. Because of the high removals using the reverse osmosis components alone, the
verifications did not test the GAC components of those devices that included the technology for
oxamyl removal (NSF, 2005a, 2005b, 2006, 2007a).

Treatment is not known to be a limiting concern for the current MCL for oxamyl. Given the
above data on removal efficiency (85% to 98% for GAC and 99% for reverse osmosis) and a
lack of demonstrated treatment effectiveness at low concentrations, however, treatment
technology could pose a limitation at concentrations as low as the health-based threshold of
0.002 mg/L.

3.5 Toluene
The current MCL for toluene is 1 mg/L and the current BATs are GAC and PTA (40 CFR
141.61). Small system compliance technologies include: GAC, PTA, diffused aeration, multi-
stage bubble aeration, tray aeration, and shallow tray aeration (USEPA, 1998). The health-based
threshold used for the Six-Year Review 2 is 0.6 mg/L (USEPA, 2009f).

According to the WHO, the achievable air stripping removal efficiency for toluene is more than
80%, to concentrations lower than 0.001 mg/L (WHO, 2006). For PTA, field studies performed
in three States demonstrated a removal efficiency of greater than 96% for toluene and other
contaminants, with initial concentrations of up to 0.6 mg/L (Ram et al., 1990 as cited in USEPA,
1998). Performance studies employing diffused aeration to treat toluene and other contaminants
have demonstrated 50% to 90% removal efficiencies (USEPA, 1985 as cited in USEPA, 1998).
For toluene, Henry's Law constants reported in several sources are relatively high, ranging from
0.126 to 0.314 atm m3/m3, indicating good treatment feasibility (Sander, 1999; Cummins and
Westrick, 1987). EPA has categorized toluene as a contaminant with good strippability (56 FR
3526, January 30, 1991).

According to the WHO, the achievable GAC removal efficiency for toluene is more than 80%, to
concentrations lower than 0.001 mg/L (WHO, 2006). Carbon usage rates for toluene (0.3050
lbs/1,000 gal) are higher than for other organic contaminants (56 FR 3526, January 30, 1991).
Although EPA found that GAC may be more than twice as expensive as PTA for large systems
on a dollar per household per year basis, if off-gas control of PTA is necessary, then costs
between PTA and GAC are more competitive (56 FR 3526, January 30, 1991).

Treatment is not known to be a limiting concern for the current MCL for toluene. The Agency's
current assessment is that treatment technology would not pose a feasibility limitation at the
health-based threshold of 0.6 mg/L.
3-4

3.6 Xylenes
The current MCL for total xylenes is 10 mg/L and the current BATs are GAC and PTA (40 CFR
141.61). Small system compliance technologies include: GAC, PTA, diffused aeration, multi-
stage bubble aeration, tray aeration, and shallow tray aeration (USEPA, 1998). The health-based
threshold used for the Six-Year Review 2 is 1 mg/L (USEPA, 2009f).

According to the WHO, the achievable air stripping removal efficiency for xylenes is more than
80%, to concentrations lower than 0.005 mg/L (WHO, 2006). Performance studies for diffused
aeration used to treat xylenes and other contaminants have demonstrated 50% to 90% removal
efficiencies (USEPA, 1985 as cited in USEPA, 1998). For xylenes, Henry's Law constants
reported in several sources are relatively high, ranging from 0.0973 to 0.341 atm mVm3,
indicating good treatment feasibility (Sander, 1999; Cummins and Westrick, 1987). EPA has
categorized xylenes as a contaminant with good strippability (56 FR 3526, January 30, 1991).

According to the WHO, the achievable GAC removal efficiency for xylenes is more than 80%,
to concentrations lower than 0.005 mg/L (WHO, 2006). One case study, cited in the U.S. Army
Corps of Engineers' Adsorption Design Guide, shows GAC removal efficiencies for xylenes of
greater than 99% at influent concentrations of 0.2 to 0.5 mg/L (U.S. Army Corps of Engineers,
2001). Carbon usage rates for xylenes (0.2148 to 0.3718 lbs/1,000 gal) are higher than for other
organic contaminants (56 FR 3526, January 30, 1991). Although EPA found that GAC may be
more than twice as expensive as PTA for large systems on a dollar per household per year basis,
if off-gas control of PTA is necessary, then costs between PTA and GAC are more competitive
(56 FR 3526, January 30, 1991).

Treatment is not known to be a limiting concern for the current MCL for xylenes. The Agency's
current assessment is that treatment technology would not pose a feasibility limitation at the
health-based threshold of 1 mg/L.

3.7 Benzene
The current MCL for benzene is 0.005 mg/L and the current BATs are GAC and PTA (40 CFR
141.61). The EQL used for the Six-Year Review 2 is 0.0005 mg/L (USEPA, 2009c). Small
system compliance technologies include: GAC, PTA, diffused aeration, multi-stage bubble
aeration, tray aeration, and shallow tray aeration (USEPA, 1998). In addition, EPA's ETV
Program recently verified the performance of several POU devices for removal of chemical
contaminants including benzene. The emerging technologies tested in the ETV verifications
included reverse osmosis, reverse osmosis followed by GAC, and advanced oxidation
(ultraviolet light combined with ozone) followed by GAC (NSF, 2005a, 2005b, 2005c, 2006,
2007a).

EPA pilot studies using PTA at more than 30 sites showed greater than 99% volatile organic
compound (VOC) removals to be achievable. Based on these and other studies, EPA concluded
that PTA systems designed using reasonable engineering practices could achieve 99% removal
of nine VOCs, including benzene, under all anticipated circumstances. Removal could be as high
as 99.9% under optimum conditions (50 FR 46902, November 13, 1985). For benzene, Henry's
Law constants in several sources are relatively high, ranging from 0.0584 to 0.341 atm m3/m3,
3-5

indicating good treatment feasibility (Sander, 1999; Crittenden, 1988; Cummins and Westrick,
1987).

EPA has concluded that GAC can achieve a high level of removal of most VOCs. Although
carbon usage rates are significantly higher for benzene than other VOCs, EPA concluded that
removal is still feasible using GAC (50 FR 46902, November 13, 1985). One case study cited in
the U.S. Army Corps of Engineers' Adsorption Design Guide shows a GAC removal efficiency
for benzene of greater than 99% at an influent concentration of 0.4 mg/L (U.S. Army Corps of
Engineers, 2001). The ETV test of a POU device using advanced oxidation followed by GAC
verified that the GAC filter component of the device removed greater than 99% of benzene, from
an influent concentration of 0.44 mg/L (NSF, 2005c).

The ETV tests of POU devices using reverse osmosis verified that the reverse osmosis
components of these devices removed 85% to greater than 99% of benzene, from influent
concentrations of 0.68 to 1.1 mg/L. Because of the high removals using the reverse osmosis
components alone, the verifications did not test the GAC components of those devices that
included the technology for benzene removal (NSF, 2005a, 2005b, 2006, 2007a).

Treatment is not known to be a limiting concern for the current MCL for benzene. The Agency's
current assessment is that treatment technology would not pose a feasibility limitation at the EQL
of 0.0005 mg/L.

3.8 Chlordane
The current MCL for chlordane is 0.002 mg/L and the current BAT is GAC (40 CFR 141.61).
The EQL used for the Six-Year Review 2 is 0.001 mg/L (USEPA, 2009c). Small system
compliance technologies include: GAC, PAC, and POU-GAC (USEPA, 1998).

According to the WHO, the achievable air stripping removal efficiency for chlordane is more
than 80%, to concentrations lower than 0.0001 mg/L (WHO, 2006). Carbon usage rates for
chlordane (0.0379 lbs/1,000 gal) are lower than for other organic contaminants, indicating good
treatment feasibility (56 FR 3526, January 30, 1991).

Treatment is not known to be a limiting concern for the current MCL for chlordane. The
Agency's current assessment is that treatment technology would not pose a feasibility limitation
at the EQL of 0.001 mg/L.

3.9 1,2-Dibromo-3-chloropropane (DBCP)
The current MCL for DBCP is 0.0002 mg/L and the current BATs are GAC and PTA (40 CFR
141.61). The EQL used for the Six-Year Review 2 is 0.0001 mg/L (USEPA, 2009c). Small
system compliance technologies include: GAC, PAC, PTA, diffused aeration, multi-stage bubble
aeration, tray aeration, and shallow tray aeration (USEPA, 1998).

The Henry's Law constant (0.00486 atm m3/m3) for DBCP is at least an order of magnitude
lower than for other contaminants such as benzene (Cummins and Westrick, 1987). EPA has
categorized DBCP as a contaminant with difficult strippability (56 FR 3526, January 30, 1991).
3-6

Carbon usage rates for DBCP are significantly lower (0.0448 lbs/1,000 gal) than for other
organic contaminants, indicating good treatment feasibility (56 FR 3526, January 30, 1991). The
City of Redlands, California, operates a GAC treatment plant to remove DBCP and
trichloroethylene (TCE) from groundwater. The carbon adsorbers typically operate for 18
months between reactivations (GWRTAC, 2001). Thus, while both aeration and carbon
adsorption are B ATs, adsorption may, in some cases, be the preferred treatment.

Treatment is not known to be a limiting concern for the current MCL for DBCP. The Agency's
current assessment is that treatment technology would not pose a feasibility limitation at the EQL
of 0.0001 mg/L.

3.10 1,2-Dichloropropane
The current MCL for 1,2-dichloropropane is 0.005 mg/L and the current BATs are GAC and
PTA (40 CFR 141.61). Small system compliance technologies include: GAC, PTA, diffused
aeration, multi-stage bubble aeration, tray aeration, and shallow tray aeration (USEPA, 1998).
The EQL used for the Six-Year Review 2 is 0.0005 mg/L (USEPA, 2009c).

Performance studies for diffused aeration used to treat 1,2-dichloropropane and other
contaminants have demonstrated 50% to 90% removal efficiencies (USEPA, 1985 as cited in
USEPA, 1998). For 1,2-dichloropropane, Henry's Law constants reported in several sources are
moderately high, ranging from 0.0481 to 0.136 atm m3/m3, indicating good treatment feasibility
(Sander, 1999; Cummins and Westrick, 1987). EPA has categorized 1,2-dichloropropane as a
contaminant with average strippability (56 FR 3526, January 30, 1991).

According to the WHO, the achievable GAC removal efficiency for 1,2-dichloropropane is more
than 80%, to concentrations lower than 0.001 mg/L (WHO, 2006). Carbon usage rates for 1,2-
dichloropropane (0.2857 lbs/1,000 gal) are somewhat higher than for other organic contaminants
(56 FR 3526, January 30, 1991). Although EPA found that GAC may be more than twice as
expensive as PTA for large systems on a dollar per household per year basis, if off-gas control of
PTA is necessary, then costs between PTA and GAC are more competitive (56 FR 3526, January
30, 1991).

Treatment is not known to be a limiting concern for the current MCL for 1,2-dichloropropane.
However, given the above data (removal efficiency 50% to 90% for aeration, with only
moderately high Henry's Law constants; removal efficiency more than 80%, to concentrations
lower than 0.001 mg/L, for GAC), treatment technology could pose a feasibility limitation at the
EQL of 0.0005 mg/L.

3.11 Heptachlor
The current MCL for heptachlor is 0.0004 mg/L and the current BAT is GAC (40 CFR 141.61).
Small system compliance technologies include: GAC, PAC, and POU-GAC (USEPA, 1998).
The EQL used for the Six-Year Review 2 is 0.0001 mg/L (USEPA, 2009c).

Carbon usage rates for heptachlor are significantly lower (0.0556 lbs/1,000 gal) than for other
organic contaminants, indicating good treatment feasibility (56 FR 3526, January 30, 1991).
3-7

Treatment is not known to be a limiting concern for the current MCL for heptachlor. The
Agency's current assessment is that treatment technology would not pose a feasibility limitation
at the EQL of 0.0001 mg/L.

3.12 Heptachlor Epoxide
The current MCL for heptachlor epoxide is 0.0002 mg/L and the current BAT is GAC (40 CFR
141.61). Small system compliance technologies include: GAC, PAC, and POU-GAC (USEPA,
1998). The EQL used for the Six-Year Review 2 is 0.0001 mg/L (USEPA, 2009c).

Carbon usage rates for heptachlor epoxide are significantly lower (0.0271 lbs/1,000 gal) than for
other organic contaminants, indicating good treatment feasibility (56 FR 3526, January 30,
1991). EPA has categorized heptachlor epoxide as a strongly adsorbed organic contaminant (54
FR 22062, May 22, 1989).

Treatment is not known to be a limiting concern for the current MCL for heptachlor epoxide.
The Agency's current assessment is that treatment technology would not pose a feasibility
limitation at the EQL of 0.0001 mg/L.

3.13 Hexachlorobenzene
The current MCL for hexachlorobenzene is 0.001 mg/L and the current BAT is GAC (40 CFR
141.61). Small system compliance technologies include: GAC, PAC, and POU-GAC (USEPA,
1998). The EQL used for the Six-Year Review 2 is 0.0001 mg/L (USEPA, 2009c).

EPA has categorized hexachlorobenzene among moderately adsorbed contaminants, exhibiting
an intermediate carbon usage rate (55 FR 30370, July 25, 1990). The agency concluded that
GAC is effective in removing SOCs including hexachlorobenzene (55 FR 30370, July 25, 1990).

Treatment is not known to be a limiting concern for the current MCL for hexachlorobenzene.
The Agency's current assessment is that treatment technology would not pose a feasibility
limitation at the health-based threshold of 0.0001 mg/L.

3.14 Toxaphene
The current MCL for toxaphene is 0.003 mg/L and the current BAT is GAC (40 CFR 141.61).
Small system compliance technologies include: GAC, PAC, and POU-GAC (USEPA, 1998).
The EQL used for the Six-Year Review 2 is 0.001 mg/L (USEPA, 2009c).

Carbon usage rates for toxaphene are significantly lower (0.0432 lbs/1,000 gal) than for other
organic contaminants, indicating good treatment feasibility (56 FR 3526, January 30, 1991).

Treatment is not known to be a limiting concern for the current MCL for toxaphene. The
Agency's current assessment is that treatment technology would not pose a feasibility limitation
at the EQL of 0.001 mg/L.
3-8

3.15 1,1,2-Trichloroethane
The current MCL for 1,1,2-trichloroethane is 0.005 mg/L and the current BATs are GAC and
PTA (40 CFR 141.61). Small system compliance technologies include: GAC, PTA, diffused
aeration, multi-stage bubble aeration, tray aeration, and shallow tray aeration (USEPA, 1998).
The health-based threshold used for the Six-Year Review 2 is the current MCLG of 0.003 mg/L
(USEPA, 2009c).

EPA indicates that 1,1,2-trichloroethane may be among the less volatile organic chemicals (55
FR 30370, July 25, 1990). Still, for 1,1,2-trichloroethane, Henry's Law constants reported in
several sources are moderately high, ranging from 0.0314 to 0.0487 atm m3/m3, indicating good
treatment feasibility (Sander, 1999).

For carbon adsorption, EPA has categorized 1,1,2-trichloroethane among moderately adsorbed
contaminants, exhibiting an intermediate carbon usage rate (55 FR 30370, July 25, 1990).

Treatment is not known to be a limiting concern for the current MCL for 1,1,2-trichloroethane.
The Agency's current assessment is that treatment technology would not pose a feasibility
limitation at the health-based threshold of 0.003 mg/L.

3.16 Vinyl Chloride
The current MCL for vinyl chloride is 0.002 mg/L and the current BAT is PTA (40 CFR 141.61).
Small system compliance technologies include: GAC, PTA, diffused aeration, multi-stage bubble
aeration, tray aeration, and shallow tray aeration (USEPA, 1998). The EQL used for the Six-Year
Review 2 is 0.0005 mg/L (USEPA, 2009c).

EPA pilot studies at more than 30 sites showed that PTA can achieve greater than 99% VOC
removals. Because vinyl chloride is more easily removed by aeration than other VOCs, EPA
concluded that PTA systems designed using reasonable engineering practices could achieve
99.9% removal of vinyl chloride under most circumstances (50 FR 46902, November 13, 1985).
Case studies using spray aeration demonstrated greater than 99% removal for vinyl chloride and
other contaminants, with initial concentrations of 100 to 200 mg/L (USEPA, 1985 as cited in
USEPA, 1998). For vinyl chloride, Henry's Law constants reported in several sources are very
high, ranging from 0.889 to 265 atm m3/m3, indicating very good treatment feasibility (Sander,
1999; Crittenden, 1988; Cummins and Westrick, 1987; Rauschert Industries, undated).

Treatment is not known to be a limiting concern for the current MCL for vinyl chloride. The
Agency's current assessment is that treatment technology would not pose a feasibility limitation
at the EQL of 0.0005 mg/L.

3.17 Carbon Tetrachloride
The current MCL for carbon tetrachloride is 0.005 mg/L and the current BATs are GAC and
PTA (40 CFR 141.61). Small system compliance technologies include: GAC, PTA, diffused
aeration, multi-stage bubble aeration, tray aeration, and shallow tray aeration (USEPA, 1998).
The EQL used for the Six-Year Review 2 is 0.0005 mg/L (USEPA, 2009c).
3-9

EPA indicates that GAC can achieve high level of removal (up to 99.9%) of VOCs, including
carbon tetrachloride, under all anticipated conditions (50 FR 46902, November 13, 1985). Case
studies cited in the U.S. Army Corps of Engineers' Adsorption Design Guide show GAC
removal efficiencies for carbon tetrachloride of greater than 99.9%, at influent concentrations of
1.0 to 135 mg/L (U.S. Army Corps of Engineers, 2001).

Treatment is not known to be a limiting concern for the current MCL for carbon tetrachloride.
The Agency's current assessment is that treatment technology would not pose a feasibility
limitation at the EQL of 0.0005 mg/L.

3.18 1,2-Dichloroethane (Ethylene Dichloride)
The current MCL for 1,2-dichloroethane is 0.005 mg/L and the current BATs are GAC and PTA
(40 CFR 141.61). Small system compliance technologies include: GAC, PTA, diffused aeration,
multi-stage bubble aeration, tray aeration, and shallow tray aeration (USEPA, 1998). The EQL
used for the Six-Year Review 2 is 0.0005 mg/L (USEPA, 2009c).

EPA pilot studies using PTA at more than 30 sites showed greater than 99% VOC removals to be
achievable. Based on these and other studies, EPA concluded that PTA systems designed using
reasonable engineering practices could achieve 99% removal of nine VOCs, including 1,2-
dichloroethane, under all anticipated circumstances. Removal could be as high as 99.9% under
optimum conditions (50 FR 46902, November 13, 1985). For 1,2-dichloroethane, Henry's Law
constants reported in several sources are moderately high, ranging from 0.023 to 0.0639 atm
m3/m3, indicating good treatment feasibility (Sander, 1999; Crittenden, 1988; Cummins and
Westrick, 1987).

EPA has concluded that GAC can achieve a high level of removal of most VOCs. Although
carbon usage rates are significantly higher for 1,2-dichloroethane than other VOCs, EPA
concluded that removal is still feasible using GAC (50 FR 46902, November 13, 1985).

Treatment is not known to be a limiting concern for the current MCL for 1,2-dichloroethane. The
Agency's current assessment is that treatment technology would not pose a feasibility limitation
at the EQL of 0.0005 mg/L.

3.19 Dichloromethane
The current MCL for dichloromethane is 0.005 mg/L and the current BAT is PTA (40 CFR
141.61). Small system compliance technologies include: GAC, PTA, diffused aeration, multi-
3-10

stage bubble aeration, tray aeration, and shallow tray aeration (USEPA, 1998). The EQL used for
the Six-Year Review 2 is 0.0005 mg/L (USEPA, 2009c).

EPA has categorized dichloromethane among the more volatile SOCs (55 FR 30370, July 25,
1990). For the volatile SOCs, properly designed PTA facilities can achieve removal efficiencies
of 90% to 99% or more (55 FR 30370, July 25, 1990). For dichloromethane, Henry's Law
constants reported in several sources are moderately high, ranging from 0.0341 to 0.132 atm
m3/m3, indicating good treatment feasibility (Sander, 1999). For GAC, EPA has concluded that
the technology is capable of removing SOCs, but is a more costly technique than PTA for
dichloromethane (55 FR 30370, July 25, 1990).

Treatment is not known to be a limiting concern for the current MCL for dichloromethane. The
Agency's current assessment is that treatment technology would not pose a feasibility limitation
at the EQL of 0.0005 mg/L.

3.20 Tetrachloroethylene
The current MCL for tetrachloroethylene is 0.005 mg/L and the current BATs are GAC and PTA
(40 CFR 141.61). Small system compliance technologies include: GAC, PTA, diffused aeration,
multi-stage bubble aeration, tray aeration, and shallow tray aeration (USEPA, 1998). The EQL
used for the Six-Year Review 2 is 0.0005 mg/L (USEPA, 2009c).

EPA pilot studies at more than 30 sites showed that PTA can achieve greater than 99% VOC
removals. Based on these and other studies, EPA concluded that PTA systems designed using
reasonable engineering practices could achieve 99% removal of nine VOCs, including
tetrachloroethylene, under all anticipated circumstances. Removal could be as high as 99.9%
under optimum conditions (50 FR 46902, November 13, 1985). According to the WHO, the
achievable air stripping removal efficiency for tetrachloroethylene is more than 80%, to
concentrations lower than 0.001 mg/L (WHO, 2006). Field studies of PTA performed in three
States demonstrated a removal efficiency of greater than 96% for tetrachloroethylene and other
contaminants, with initial concentrations of up to 0.6 mg/L (Ram et al., 1990 as cited in USEPA,
1998). Performance studies employing multiple tray aeration to treat tetrachloroethylene and
other contaminants have demonstrated 50% to 90% removal efficiencies (USEPA, 1985 as cited
in USEPA, 1998). For tetrachloroethylene, Henry's Law constants reported in several sources
are high, ranging from 0.214 to 1.20 atm m3/m3, indicating good treatment feasibility (Sander,
1999; Cummins and Westrick, 1987; Rauschert Industries, undated). EPA has categorized
tetrachloroethylene as a contaminant with good strippability (56 FR 3526, January 30, 1991).

According to the WHO, the achievable GAC removal efficiency for tetrachloroethlyene is more
than 80%, to concentrations lower than 0.005 mg/L (WHO, 2006). Case studies cited in the U.S.
Army Corps of Engineers' Adsorption Design Guide show GAC removal efficiencies for
tetrachloroethylene of greater than 99.9%, at influent concentrations of 4.5 to 170 mg/L (U.S.
Army Corps of Engineers, 2001). EPA has concluded that GAC can achieve a high level of
removal (up to 99.9%) of VOCs, including tetrachloroethlyene, under all anticipated conditions
(50 FR 46902, November 13, 1985). Carbon usage rates for tetrachloroethylene (0.1144
lbs/1,000 gal) are relatively low compared with other organic contaminants, indicating good
treatment feasibility (56 FR 3526, January 30, 1991).
3-11

Treatment is not known to be a limiting concern for the current MCL for tetrachloroethylene.
The Agency's current assessment is that treatment technology would not pose a feasibility
limitation at the EQL of 0.0005 mg/L.

3.21 Trichloroethylene
The current MCL for trichloroethylene is 0.005 mg/L and the current BATs are GAC and PTA
(40 CFR 141.61). Small system compliance technologies include: GAC, PTA, diffused aeration,
multi-stage bubble aeration, tray aeration, shallow tray aeration, spray aeration, and mechanical
aeration (USEPA, 1998). The EQL used for the Six-Year Review 2 is 0.0005 mg/L (USEPA,
2009c).

EPA pilot studies at more than 30 sites showed that PTA can achieve greater than 99% VOC
removals. Based on these and other studies, EPA concluded that PTA systems designed using
reasonable engineering practices could achieve 99% removal of nine VOCs, including
trichloroethylene, under all anticipated circumstances. Removal could be as high as 99.9% under
optimum conditions (50 FR 46902, November 13, 1985). Field studies of PTA performed in
three States demonstrated a removal efficiency of greater than 96% for trichloroethylene and
other contaminants, with initial concentrations of up to 0.6 mg/L (Ram et al., 1990 as cited in
USEPA, 1998). Performance studies employing multiple tray aeration to treat trichloroethylene
and other contaminants have demonstrated 50% to 90% removal efficiencies (USEPA, 1985 as
cited in USEPA, 1998). Other case studies using spray aeration demonstrated greater than 99%
removal for trichloroethylene and other contaminants, with initial concentrations of 100 to 200
mg/L (USEPA, 1985 as cited in USEPA, 1998). For trichloroethylene, Henry's Law constants
reported in several sources are relatively high, ranging from 0.116 to 0.552 atm mVm3, indicating
good treatment feasibility (Sander, 1999; Crittenden, 1988; Cummins and Westrick, 1987;
Rauschert Industries, undated).

Case studies cited in the U.S. Army Corps of Engineers' Adsorption Design Guide show GAC
removal efficiencies for trichloroethylene of greater than 99.9%, at influent concentrations of 3
to 50 mg/L (U.S. Army Corps of Engineers, 2001). EPA has concluded that GAC can achieve a
high level of removal (up to 99.9%) of VOCs, including trichloroethylene, under all anticipated
conditions (50 FR 46902, November 13, 1985). The City of Redlands, California, operates a
GAC treatment plant to remove trichloroethylene and DBCP from groundwater. The carbon
adsorbers typically operate for 18 months between reactivations (GWRTAC, 2001).

Treatment is not known to be a limiting concern for the current MCL for trichloroethylene. The
Agency's current assessment is that treatment technology would not pose a feasibility limitation
at the EQL of 0.0005 mg/L.
3-12

-------
EPA-OGWDW           Water Treatment Technology Feasibility Support       EPA 815-B-09-007
                 Document for Chemical Contaminants for the Second Six-Year      October 2009
	Review of National Primary Drinking Water Regulations	

4  Review of Treatment Techniques  for Acrylamide and
    Epichlorohydrin

Acrylamide and epichlorohydrin are introduced in drinking water primarily as impurities in
polymers and copolymers used for water treatment and in contact surfaces used in storage and
distribution systems. EPA proposed drinking water regulations for acrylamide and
epichlorohydrin in 1989 (54 FR 22062, May 22, 1989) and promulgated final drinking water
regulations in 1991 (56 FR 3526, January 30, 1991). As both these contaminants are classified as
probable human carcinogens (B2), EPA established the MCLGs for both at zero. EPA has
regulated these contaminants using a treatment technique requirement in lieu of a MCL because
of the absence of standardized analytical methods for their measurement in water. The NPDWR
limits the allowable monomer level in products used for water treatment and the dosage of
polymers that contain them. EPA selected this option because methods are available for
measurement of residual monomer in polymer products and these levels are routinely measured
by manufacturers. These levels are:

•   Acrylamide: 0.05% residual acrylamide in polymers/copolymers and maximum dosage of 1
    ppm (or equivalent)
•   Epichlorohydrin: 0.01% residual epichlorohydrin in polymers/copolymers and maximum
    dosage of 20 ppm (or equivalent).

The residual monomer level for each contaminant was considered to be the lowest level
manufacturers could feasibly achieve at the time EPA promulgated the regulation (54 FR 22062,
May 22, 1989). A system can use third-party or manufacturer's certification in lieu of testing for
the residual monomer level.

NSF International (NSF), a third party organization,  tests and certifies water treatment chemicals
that meet NSF/ANSI Standard 60, Drinking Water Treatment Chemicals - Health Effects, which
sets out requirements for treatment chemicals based on human health protection (NSF, 1999a).
The requirements for acrylamide- and epichlorohydrin-based polymers in Standard 60 are based
on EPA's treatment technique requirements. Thus, NSF 60 certification of a polymeric coagulant
aid containing acrylamide or epichlorohydrin indicates that users are in compliance with EPA's
regulation when a product is used as specified (i.e., for the intended purpose and up to the
maximum usage level indicated by NSF).

EPA obtained data during Six-Year Review 2 indicating that potential improvements in the
technology or manufacturing now allow production of the polymer with lower residual monomer
content. This new information viewed in conjunction with regulations and guidelines in other
countries suggests there is potential for EPA to revise its TT requirement to reflect a lower
feasible monomer content.
                                         4-1

-------
EPA-OGWDW
Water Treatment Technology Feasibility Support
Document for Chemical Contaminants for the Second Six-Year
Review of National Primary Drinking Water Regulations
EPA815-B-09-007
October 2009
4.1 Improvements in Manufacturing
In 2007, NSF provided EPA with results of NSF analyses between January 2005 and June 2007
of acrylamide monomer in polyacrylamides and free epichlorohydrin in polyamines.l NSF
performed the analyses for approval of these products against NSF/ANSI Standard 60. Exhibit
4-1 provides a summary of the results. The Appendix contains the data NSF provided to EPA.

Residual levels in the products tested and certified are well below the residual levels in the
current TTs. The mean concentration among acrylamide tests is about one-fifth the residual level
in the current TT, and the 90th percentile result is one-half the residual level in the current TT.
All analyses for residual epichlorohydrin were non-detects, with a detection limit equal to one-
fifth the residual level in the current TT.

Exhibit 4-1. Summary of NSF International Product Testing Results for Acrylamide
and Epichlorohydrin
Contaminant
Acrylamide4
Epichlorohydrin5
Number of
Analyses
and
Detections1
66 [45]
84 [0]
Detection
Limit
(mg/kg)
10
20
Summary of Results (mg/kg)
Maximum
420
NA
90th
Percentile
250
NA
Mean2
98
NA
Median2
60
NA
Minimum
10
NA
Current
TT
(mg/kg)3
500
100
NA = not applicable - all results are below the detection limit.
1. Total number of analyses appears first. The number of results above the detection limit appears second, in brackets.
2. Includes nondetected values for acrylamide, assumed to be 10 mg/kg.
3. TT residual monomer content converted from percent to mg/kg; 1 mg/kg = 1/106 = 0.000001 = 0.0001%.
4. Method: Per Skelly and Husser (1978).
5. Method: Per section B.4.3.1 in NSF 60-2005.
4.2 Regulations and Guidelines in Other Countries
Regulations in other areas of the world are generally more stringent than the current EPA
NPDWR for acrylamide and epichlorohydrin in drinking water. Exhibit 4-2 provides a
comparison of recommendations and guidelines used elsewhere to EPA's current regulations.

Canada has no national regulations regarding acrylamide or epichlorohydrin. However, many
provinces require NSF 60 certification for additives used in drinking water treatment (Lemieux,
2007). The residual monomer and dosage requirements for NSF 60 certification are based on
those in EPA's current NPDWR.
1 NSF did not provide any confidential business information such as which manufacturers were included in the
analyses. NSF only provided vectors of testing results.
4-2

-------
EPA-OGWDW            Water Treatment Technology Feasibility Support        EPA 815-B-09-007
                   Document for Chemical Contaminants for the Second Six-Year       October 2009
	Review of National Primary Drinking Water Regulations	

     Exhibit 4-2. Comparison of Acrylamide and Epichlorohydrin Drinking Water
                                          Guidelines
Country/Region
US EPA
Canada
United Kingdom2
European Union3
WHO4
Australia5
Regulation or Guideline
Residual Monomer
Maximum Dosage
Expected Concentration in Water1
Acrylamide
0.05%
1mg/L
0.5 Mg/L
Epichlorohydrin
0.01%
20 mg/L
2 Mg/L
NSF 60 certification required in many provinces; see text below
Residual Monomer
Maximum Dosage
Expected Concentration in Water1
Concentration in Water
Concentration in Water
Concentration in Water
0.02%
0.25 mg/L (average)
0.5 mg/L (maximum)
0.05 ug/L (average)
0.1 ug/L (maximum)
0.1 Mg/L
0.5 ug/L
0.2 ug/L
0.002%
2.5 mg/L (average)
5 mg/L (maximum)
0.05 Mg/L (average)
0.1 Mg/L (maximum)
0.1 Mg/L
0.4 Mg/L
0.5 Mg/L
 1. The expected monomer concentration in water is the product of the maximum dosage and the residual monomer
 level, using the worst-case assumption that all residual monomer remains in finished water.
 2. DWI (2007) and Ashworth (2007). The UK limits both the average and the maximum polymer dose.
 3. OJEC (1998). The concentration is "the residual monomer concentration  in the water as calculated according to
 specifications of the maximum release from the corresponding polymer in contact with the water."
 4. WHO (2006). The World Health Organization's recommendation for epichlorohydrin is a provisional guideline
 value because there is evidence of a hazard, but the available information on health effects is limited (WHO, 2004).
 5. NHMRC (2004). The guideline value for epichlorohydrin is below the limit of determination; improved analytical
 procedures are required for this compound.
                                               4-3

5 References

Ashworth, J. 2007. Personal communication from John Ashworth, UK Drinking Water
Inspectorate, to Jitendra Saxena, U.S. EPA. 10 May.

Crittenden, J. et al. 1988. "Using GAC to Remove VOCs from Air Stripper Off-Gas." J.AWWA,
80(5). (As cited in Clark, R. and J. Adams. EPA'sDrinking Water andGroundwater
Remediation Cost Evaluation: Air Stripping. Lewis Publishers.)

Cummins, M. and J. Westrick. 1987. "Feasibility of Air Stripping for Controlling Moderately
Volatile Synthetic Organic Chemicals." Presented at 1987 AWWA Conference. Reprinted in
Best Available Technology Peer Review Conference: Final Report. U.S. EPA.

Drinking Water Inspectorate (DWI), United Kingdom. 2007. List of Approved Products. July.
http://www.dwi.gov.uk/31/pdf/soslist06.pdf.

Ground-Water Remediation Technologies Analysis Center (GWRTAC). 2001. Technology
Status Report: Perchlorate Treatment Technologies, First Edition. Pittsburgh, PA. May.

Lemieux, F. 2007. Personal communication from F. Lemieux, Health Canada, to Rajiv Khera,
U.S. EPA. 16 October.

National Health and Medicine Research Council (NHMRC), Australia. 2004. Australian
Drinking Water Guidelines, http://www.nhmrc.gov.au/publications/synopses/ehl9syn.htm.

NSF International (NSF). 1999a. NSF Drinking Water Additives Program: The Second Decade.
http://www.nsf.org/business/newsroom/waterworks99-l/index.html.

NSF International (NSF). 1999b. Summary Report: NSF International Extraction Results (1991
to 1998), ANSI/NSF Standard 61: Drinking Water System Components - Health Effects. Report
prepared for Health Canada, http://www.hc-sc.gc.ca/ewh-semt/water-eau/drink-
potab/mater/nsf_components_e.html.

NSF International (NSF). 2000. Review of Contaminant Occurrences in Drinking Water
Treatment Chemicals: A Summary Report of NSF International Results (1991 to 1999),
ANSI/NSF Standard 60: Drinking Water Treatment Chemicals - Health Effects. Report prepared
for Health Canada. 31 March, http://www.hc-sc.gc.ca/ewh-semt/water-eau/drink-
potab/mater/nsf chemicals-chimiques e.html.

NSF International (NSF). 2005a. Environmental Technology Verification Report: Removal of
Chemical Contaminants in Drinking Water, EcoWater Systems Incorporated ERO-R450E
Drinking Water Treatment System. Prepared by NSF International under a Cooperative
Agreement with U.S. Environmental Protection Agency. NSF 05/14b/EPADWCTR. September.

NSF International (NSF). 2005b. Environmental Technology Verification Report: Removal of
Chemical Contaminants in Drinking Water, Kinetico Incorporated Pall/Kinetico Purefecta™
5-1

Drinking Water Treatment System. Prepared by NSF International under a Cooperative
Agreement with U.S. Environmental Protection Agency. NSF 05/13b/EPADWCTR. September.

NSF International (NSF). 2005c. Environmental Technology Verification Report: Removal of
Chemical Contaminants in Drinking Water, Watts Premier Incorporated WP-4V Drinking Water
Treatment System. Prepared by NSF International under a Cooperative Agreement with U.S.
Environmental Protection Agency. NSF 05/12c/EPADWCTR. November.

NSF International (NSF). 2006. Environmental Technology Verification Report: Removal of
Chemical and Microbial Contaminants in Drinking Water, Watts Premier, Inc. M-2400 Point-of-
Entry Reverse Osmosis Drinking Water Treatment System. Prepared by NSF International under
a Cooperative Agreement with U.S. Environmental Protection Agency. NSF
06/23/EPADWCTR. September.

NSF International (NSF). 2007a. Environmental Technology Verification Report: Removal of
Synthetic Organic Chemical Contaminants in Drinking Water, RASco, Inc. Advanced
Simultaneous Oxidation Process (ASOP™). Prepared by NSF International under a Cooperative
Agreement with U.S. Environmental Protection Agency. NSF 06/25/EPADWCTR. September.

NSF International (NSF). 2007b. NSF Product and Service Listings: NSF/ANSI Standard 60:
Drinking Water Treatment Chemicals - Health Effects. List of search results with Chemical
Name equal to Polyacrylamide. Search performed 25 October.
http://www.nsf org/Certified/PwsChemicals/Listings.asp?CompanyName=&TradeName=&Che
mi calName=Poly acryl ami de&ProductFuncti on=&Pl ant State=&Pl antCountry=.

NSF International (NSF). 2007c. NSF Product and Service Listings: NSF/ANSI Standard 60:
Drinking Water Treatment Chemicals - Health Effects. List of search results with Chemical
Name equal to Polyamines. Search performed 25 October.
http://www.nsf org/Certified/PwsChemicals/Listings.asp?ChemicalName=Polyamines&Product
Function=&PlantState=&PlantCountry=.

NSF and Association of State Drinking Water Administrators (ASDWA). 2006. Survey of
ASDWA Members: Use of NSF Standards and ETV Reports. March.
http://www.nsf org/business/water distribution/pdf/ASDWA Survey 2006.pdf

Official Journal of the European Communities (OJEC). 1998. Council Directive 98/83/EC of 3
November 1998 on the quality of water intended for human consumption.

Purkiss, D. 2007. Personal communication from D. Purkiss, NSF International, to Jitendra
Saxena, U.S. EPA. 7 November.

Ram, N.M., R.F. Christman, and K.P. Cantor. 1990. Significance and Treatment of Volatile
Organic Compounds in Water Supplies. Lewis Publishers. (As cited in USEPA, 1998.)

Rauschert Industries, Inc. Undated. Removal of Volatile Organic Compounds from Water.
Brochure APP-02.
5-2

Sander, R. 1999. Compilation of Henry's Law Constants for Inorganic and Organic Species of
Potential Importance in Environmental Chemistry (Version 3). http://www.mpch-
mainz.mpg.de/~sander/res/henry.html

Skelly, Norman E., and Edward R. Husser. 1978. "Determination of Acrylamide Monomer in
Polyacrylamide and in Environmental Samples by High Performance Liquid Chromatography."
Analytical Chemistry, 50: 1959-1962. First page online at
http://pubs3.acs.org/acs/journals/toc.page?incoden=ancham&indecade=3&involume=50&inissue
=14.

U. S. Army Corps of Engineers. 2001. Adsorption Design Guide. Design Guide No. 1110-1-2.
Department of the Army, U.S. Army Corps of Engineers. Washington, DC. 1 March.
http://www.usace.army.mil/publications/design-guides/dglllO-l-2/entire.pdf

USEPA. 2009a. Analysis of Occurrence Data from the Second Six-Year Review of Existing
National Primary Drinking Water Regulations. EPA 815-B-09-006.

USEPA. 2009b. Analytical Feasibility Support Document for the Second Six-Year Review of
Existing National Primary Drinking Water Regulations. EPA 815-B-09-003.

USEPA. 2009c. Development of Estimated Quantitation Levels for the Second Six-Year Review
of National Primary Drinking Water Regulations. EPA 815-B-09-005.

USEPA. 2009d. EPA Protocol for the Second Review of Existing National Primary Drinking
Water Regulations (Updated). EPA 815-B-09-002.

USEPA. 2009e. Occurrence Analysis for Potential Source Waters for the Second Six-Year
Review of National Primary Drinking Water Regulations. EPA 815-B-09-004.

USEPA. 2009f. Six-Year Review 2 - Health Effects Assessment - Summary Report. EPA 822-
R-09-006.

USEPA. 2009g. Consideration of Other Regulatory Revisions in Support of the Second Six-Year
Review of the National Primary Drinking Water Regulations. EPA 815-B-09-008.

USEPA. 2007. Simultaneous Compliance Guidance Manual For The Long Term 2 And Stage 2
DBF Rules. Office of Water. EPA 815-R-07-017. March.

USEPA. 2003. EPA Protocol for Review of Existing National Primary Drinking Water
Regulations. EPA 815-R-03-002. June.

USEPA. 1999. Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual.
Office of Water. EPA 815-R-99-012. May.

USEPA. 1998. Small System Compliance Technology List for the Non-Microbial Contaminants
Regulated before 1996. Office of Water. EPA 815-R-98-002. September.
5-3

-------
EPA-OGWDW           Water Treatment Technology Feasibility Support        EPA 815-B-09-007
                 Document for Chemical Contaminants for the Second Six-Year      October 2009
	Review of National Primary Drinking Water Regulations	

USEPA. 1990. Technologies and Costs for the Removal of Phase V Synthetic Organic
Chemicals from Potable Water Supplies. Office of Drinking Water. September.

USEPA. 1985. Technologies and Costs for the Removal of Volatile Organic Chemicals from
Potable Water Supplies. (As cited in USEPA, 1998.)

World Health Organization (WHO). 2004. Epichlorohydrin in Drinking-water.
WHO/SDE/WSH/03.04/94.

World Health Organization (WHO). 2006. Guidelines for Drinking-water Quality: Incorporating
First Addendum, Vol. 1, Recommendations. 3rd Edition. World Health Organization. Geneva,
Switzerland, http://www.who.int/water sanitation health/dwq/gdwq3rev/en/index.html
                                          5-4

-------
EPA-OGWDW
Water Treatment Technology Feasibility Support
Document for Chemical Contaminants for the Second Six-Year
Review of National Primary Drinking Water Regulations
EPA815-B-09-007
October 2009
Appendix: Monomer Data from NSF International
In 2007, NSF International (NSF) provided EPA with the results of NSF analyses of aery 1 amide
monomer in polyacrylamides and free epichlorohydrin in polyamines certified to NSF/ANSI
Standard 60. The analyses were performed between January 2005 and June 2007. The data that
NSF provided is reproduced here.

NSF determined the residual acrylamide content in 66 samples of commercial polyacrylamides,
using the method described by Skelly and Husser (1978) with a detection limit of 10 mg
acrylamide per kg polymer. NSF provided only a vector of test results; it did not provide
manufacturer or product names or any other competition-sensitive information. Exhibit A-l
provides a frequency distribution for the data that NSF provided to EPA.

Exhibit A-1. NSF International Data on Acrylamide Monomer in Polyacrylamide
Measurement (mg/kg)
ND1
10
20
30
40
60
70
80
90
100
110
120
140
150
170
180
210
220
280
320
340
360
410
420
Number of Samples
21
2
1
2
6
2
3
2
2
3
1
1
3
2
2
2
2
2
1
2
1
1
1
1
ND = nondetect.
1. Detection limit was 10 mg/kg.

NSF provided EPA with measurements of the amount of residual epichlorohydrin in 84 samples
of commercial polyamines, using the method described in section B.4.3.1 of NSF 60-2005 with a
detection limit of 20 mg epichlorohydrin per kg polymer. NSF provided only a vector of test
A-1

-------
EPA-OGWDW           Water Treatment Technology Feasibility Support        EPA 815-B-09-007
                  Document for Chemical Contaminants for the Second Six-Year      October 2009
	Review of National Primary Drinking Water Regulations	

results, with no manufacturer or product names or other competition-sensitive information. None
of the 84 measurements found epichlorohydrin in a concentration greater than the detection limit.
                                           A-2

-------