Federal Register/Vol. 68, ijfo. 86/Monday, May 5, 2003/Proposed Rules
23673
Underground Injection Control-
Revisions of Underground Injection
Control Requirements for Class I
Municipal Wells in Florida;
Notice of Availability ;
EPA 816-Z-03-001
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 146
[FRL-7488-8]
Underground Injection Control
Program—Relative Risk Assessment
of Management Options for Treated
Wastewater in South Florida; Notice of
Availability
AGENCY: Environmental Protection
Agency.
ACTION: Notice of availability.
SUMMARY: On July 7, 2000, the
Environmental Protection Agency (EPA)
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proposed revisions to the Underground
injection Control (UIC) regulations that
would allow for continued wastewater
Injection by existing Class I municipal
wells that have caused or may cause the
movement of fluid into or between
underground sources of drinking water
(USDWs) in specific areas of South
Florida. These revisions would provide
owners and operators of such wells with
an alternative for compliance with the
existing UIC regulations, which prohibit
such fluid movement, by allowing them
to continue using their wells provided
the injection does not endanger USDWs.
Also in 2000, in a separate but related
initiative, Congress directed EPA to
conduct a relative risk assessment of
four management options for treated
municipal wastewater in South Florida:
deep (Class I municipal) well injection,
ocean disposal, surface discharge, and
aquifer recharge. This document
announces the availability of the
relative risk assessment report required
by Congress. EPA will consider the
information collected on deep (Class I
municipal) well injection contained in
this relative risk assessment imnakihg
a final determination on the July 7,
2000, proposed rule. In a separate
document in today's Federal Register,
EPA is soliciting public comment on
how this information in the relative risk
assessment should inform the final rule
on deep municipal wastewater injection
in South Florida.
DATES: Comments on this notice of the
data availability must be in writing and
either postmarked or received by the
docket by July 7, 2003.
ADDRESSES: Send written comments to:
Nancy H. Marsh, U.S. Environmental
Protection Agency, Region 4, 61 Forsyth
Street, SW., Atlanta, GA 30303-8960.
Comments must be submitted
electronically to marsh.nancy@epa.gov.
For additional information see
Additional Docket Information in the
SUPPLEMENTARY INFORMATION Section of
this Federal Register document.
FOR FURTHER INFORMATION CONTACT: For
inquiries, and/or to access the risk
assessment report, contact Nancy H.
Marsh, Ground Water & UIC Section,
EPA Region 4, 61 Forsyth Street, SW,
Atlanta, GA 30303 (phone: 404-562-
9450; E-mail: marsh.nancy@epa.gov) or
Howard Beard, Office of Ground Water
and Drinking Water, U.S. Environmental
Protection Agency, EPA East, 1200
Pennsylvania Ave., NW., Mail Code
4606M, Washington, DC 20460 (phone:
202-564-3874; E-mail:
beard.howard@epa.gov} or contact the
Safe Drinking Water Hotline, phone
800-426-4791. The Safe Drinking Water
Hotline is open Monday through Friday,
excluding Federal holidays, from 9 a.m.
to 5:30 p.m. Eastern daylight-saving
time.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. General Information
Who Are Regulated/Affected Entities?
II. Background
A. Definition of Class I Municipal Wells
B. Proposed Rule for Class I Municipal
Wells in Florida
C. Relative Risk Assessment of
Management Options for Treated
Municipal Wastewater in South Florida
HI. Findings of the Relative Risk Assessment
A. What Level of Treatment and
Disinfection Is Provided?
1. Deep Well Injection
2. Ocean Disposal
3. Aquifer Recharge
4. Surface Discharge
B. What Stressors Remain (After
Treatment) That May Be a Concern?
C. What Exposure Pathways Are (or May
Be) of Significance?
D. What Is the Overall Estimate of Risk?
1. Human Health
2. Ecological Health
E. What Are the Important Data or
Knowledge Gaps?
I. General Information
Who Are Regulated/Affected Entities?
This notice is limited in application
to the owners and/or operators of
existing deep (Class I) underground
injection wells that inject domestic
wastewater effluent in specific counties
in Florida. The counties are: Brevard,
Broward, Charlotte, Collier, Dade,
Flagler, Glades, Hendry, Highlands,
Hillsborough, Indian River, Lee,
Manatee, Martin, Monroe, Okeechobee,
Orange, Osceola, Palm Beach, Pinellas,
St. Johns, St. Lucie, Sarasota, and
Volusia. Regulated categories and
entities include:
Category
Municipalities and Local Government
Private
Examples of entities
Class 1 municipal injection wells disposing of domestic wastewater ef-
fluent in certain parts of Florida.
fluent in certain parts of Florida.
This table is not intended to be
exhaustive, but rather provides a guide
for readers regarding entities likely to be
interested in this notice. This table lists
the types of entities that EPA is now
aware of that could potentially be
affected by decisions related to this
notice. Other types of entities could
potentially be affected by such
decisions. To determine whether your
injection well might be affected, you
should carefully examine the
applicability criteria in 40 CFR 146.15
of the July 7, 2000, proposed revisions
to the Class I UIC regulations (65 FR
42234). If you have questions regarding
the applicability of this action to a
particular entity, consult one of the
persons listed in the preceding FOR
FURTHER INFORMATION CONTACT section.
n. Background
A. Definition of Class I Municipal Wells
Class I injection wells are wells that
inject fluids beneath the lowermost
formation containing, within one-
quarter mile of a well bore, a USDW (40
CFR 144.6(a)). Class I wells can be used
to inject hazardous, industrial, or
municipal wastes. Class I municipal
wells inject treated wastewater from
publicly or privately owned and
operated facilities that treat domestic
wastewater, which is principally
derived from dwellings, business
buildings, and institutions. Domestic
wastewater is commonly referred to as
sanitary wastewater or sewage. Treated
wastewater from industrial facilities,
often controlled through pretreatment
standards, may also be found in this
wastewater. Currently, Class I municipal
wells are located only in the State of
Florida.
B. Proposed Rule for Class I Municipal
Wells in Florida
EPA has established minimum
requirements for Class I municipal wells
and other underground injection
activities through a series of UIC
regulations at 40 CFR parts 144 through
147, developed under the authority of
the Safe Drinking Water Act. These
regulations ensure that Class I
municipal wells will not endanger
USDWs by prohibiting the movement of
any contaminant into USDWs.
On July 7, 2000, EPA proposed
revisions to the UIC regulations that
would allow continued wastewater
injection by existing Class I municipal
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Federal Register/Vol. 68, No. 86/Monday, May 5, 2003/Proposed Rules
23675
wells that have caused or may cause
movement of contaminants into USDWs
in specific areas of Florida (65 FR
42234). Continued injection would be
allowed only if owners or operators
meet certain requirements that provide
adequate protection for USDWs. In the
alternative, if new requirements are not
promulgated, owners and/or operators
of wells targeted by the proposal would
be required to close their wells and
adopt different wastewater disposal
practices, which could consist of surface
water disposal, ocean outfall, and/or
reuse. Use of these alternative disposal
practices would likely require the
construction of systems for advanced
wastewater treatment, nutrient removal,
and high-level disinfection.
The preamble to the proposed rule
describes in detail the history of
domestic wastewater injection in
Florida, the features of Florida geology
that have allowed some of that injected
wastewater to enter USDWs, and the
two major (as •well as subsidiary)
regulatory options EPA proposed to
address this is,sue in a manner that
would permit continued injection that
would not endanger USDWs. EPA
received approximately 1,200 comments
on the proposal (the comment period
closed on October 22, 2000). The
Agency will address these comments,
along with comments received in
response to the related notice published
separately in today's Federal Register,
as part of the final determination on this
rulemaking.
C. Relative Risk Assessment of
Management Options for Treated
Municipal Wastewater in South Florida
As part of EPA's Fiscal Year 2000
Appropriations bill, Congress included
the following provision: "Within
available funds, the conferees direct
EPA to conduct a relative risk
assessment of deep well injection, ocean
disposal, surface discharge, and aquifer
recharge of treated effluent in South
Florida, in close cooperation with the
Florida Department of Environmental
Protection [DEP] and South Florida
municipal water utilities." Because this
directive came at a time when EPA's
work on the July 7, 2000, proposal was
substantially complete, the Agency
decided to proceed with the proposal
and the relative risk assessment along
separate but converging paths. First,
EPA published and sought comment on
the proposal based on information
available at that time. Second, EPA
initiated and conducted the relative risk
assessment with the intent of using
relevant findings to inform the final
rulemaking.
EPA started the relative risk
assessment by working with
stakeholders to develop an appropriate
methodology. The Agency first outlined
a proposed methodology following
standard risk assessment principles and
guidance,! such as the "Guide for
Developing Conceptual Models for
Ecological Risk Assessments." 1 EPA
then held a stakeholders meeting on
March 20| 2001, in Tallahassee, Florida
to discuss the proposed methodology.
The meeting was attended by 17
stakeholders representing municipal
water utilities, regulators, and
community and environmental groups.
Participants offered comments on the
proposed methodology, which EPA
revised accordingly.
The methodology involved a process
for investigating the four very different
wastewater disposal options: deep well
injection, aquifer recharge, discharge to
ocean outfalls, and discharge to other
(non-ocean) surface water bodies. Each
option has its own specific stressors
(hazards),; exposure pathways, receptors,
and effects. Parameters that are relevant
to one particular disposal option are not
necessarily relevant to the remaining
three. Therefore, a strictly quantitative
comparison between the four options
was not possible.
Instead, EPA conducted what is
termed a relative risk assessment to
assess the^risks and allow comparisons.
Individual risk assessments were
completed for each wastewater disposal
option anijl the risks associated with
each were characterized. The risks and
risk factors identified for each
wastewater management option were
then evaluated and described. The
overall comparisons and conclusions
were then presented as relative risk
assessment matrices.
The steps involved in the relative risk
assessment included developing a
Generic Risk Analysis Framework
followed by conducting analyses of
option-specific conceptual models. Data
from many sources were used to support
the analyses. These sources include the
Florida Department of Environmental
Protection, utilities (and the South
Florida Water Environment Utility
Council), and municipalities in South
Florida. EPA also worked with a panel
of experts both inside and outside of
EPA and representing a variety of fields
to review Łnd incorporate data and
information acquired through
comprehensive searches of the relevant
scientific research literature. Risk
1 Prepared by G.W. Suter II of Oak Ridge National
Laboratory for the U.S. Department of Energy.
Report No. ES/ER/TM-186 issued in May 1996.
Available at
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23676
Federal Register/Vol. 68, No. 86/Monday, May 5, 2003/Proposed Rules
example, treatment of waste-water that is
injected by Class I municipal wells in
Dado and Brevard Counties consists of
secondary treatment with no
disinfection, although backup
disinfection capability is required. In
contrast, in Pinellas County, wastewater
is treated to more stringent reclaimed
water standards before being discharged
into Class I municipal wells, because
the Class 1 wells are used to dispose of
reclaimed water during periods of wet
weather. Reclaimed water standards, as
specified by the State of Florida, include
secondary treatment plus a variety of
techniques to remove microorganisms,
including basic disinfection, filtration,
and high-level disinfection.
2. Ocean Disposal
Utilities in South Florida that employ
ocean disposal provide basic
disinfection in addition to secondary
treatment prior to discharge. Basic
disinfection removes fecal coliform
bacteria by treating the wastewater with
chlorine. However, wastewater that is •
discharged into the ocean does not
undergo filtration. This means that
pathogenic protozoans, such as
Cryptospotidium, Giardia, and other
chlorine-resistant microorganisms, may
remain in the treated wastewater.
3. Aquifer Recharge
Utilities that employ aquifer recharge
(which includes but is not limited to
replenishment of surficial aquifers
through irrigation, wetlands discharge,
or discharge to percolation ponds) treat
to reclaimed water standards prior to
discharge. Small amounts of nitrogen
and phosphorus and trace amounts of
other inorganic and organic constituents
remain. However, viruses and bacteria
are inactivated and Cryptospotidium
and Giardia are largely removed through
filtration.
4. Surface Discharge
Utilities in South Florida that employ
surface water discharges provide
advanced treatment as required to meet
State water quality-based effluent limits.
Advanced wastewater treatment
Includes secondary treatment, basic
disinfection, filtration, high-level
disinfection, removal of chlorine
following disinfection (i.e.,
dcchlorination), and further removal of
nitrogen and phosphorus. It represents
the highest level of treatment conducted
in South Florida.
B. What Stressors Remain (After
Treatment) That May Be a Concern?
"Stressors" include chemical or
biological agents that may cause adverse
effects if exposure levels are high
enough. The relative risk assessment
report describes the human health and
ecological health Stressors that may be
found in wastewater effluent after it has
been treated and that may pose a risk.
C. What Exposure Pathways Are (or May
Be) of Significance?
An "exposure pathway" is the course
a stressor takes from a source of release
to an exposed organism. It is defined by
the different environmental media
through which a stressor migrates (e.g.,
air, surface water, ground water) as well
as the mechanism by which an organism
is actually exposed (e.g., inhalation,
drinking, topical contact). The relative
risk assessment report discusses a
variety of exposure pathways by which
humans, plants, and animals may be
exposed to municipal wastewater
contaminants under each of the
management options.
D. What Is the Overall Estimate of Risk?
Although the report does not quantify
risks, it offers conclusions about the
relative risks of the four wastewater
management options and about the
various factors that influence risks to
human and ecological health.
1. Human Health
The human health risks associated
with all four management options in
South Florida are generally low. While
it is difficult to compare the overall
risks of the options directly, a relative
comparison can be made on the basis of
certain factors that tend to increase or
decrease the risks of one or more
options relative to the others. In
particular, as discussed in turn in the
following paragraphs, relative human
health risks are higher when: (1) An
option provides less wastewater
treatment; (2) is more likely to
contaminate current or potential
drinking supplies; and (3) is more likely
to result in people being exposed to
discharged contaminants in other ways
besides drinking.
The degree of wastewater treatment,
and in particular the level of
disinfection and filtration of pathogenic
microorganisms (Cryptospotidium,
Giardia), is a major risk driver. Clearly,
there is greater potential risks associated
with wastewater that is not treated to
remove microorganisms. This would
suggest higher relative risks for the deep
well injection and ocean disposal
options, which generally do not filter
wastewater to remove Cryptospotidium
and Giardia prior to disposal. Looking
just at deep well injection, the risk
would be highest in situations where
the injectate migrates through fractures,
faults, and solution cavities. The risk
associated with Cryptospotidium and
Giardia being released by deep well
injection would be mitigated somewhat
in situations where the injection is
dominated by porous media flow,
characterized by long travel times to
current or potential drinking water
sources and fine pore spaces capable of
retaining microorganisms.
Once Cryptosporidium, Giardia, and
other Stressors are released to the
environment, the level of risk they pose
to human health depends largely on
how likely they are to enter drinking
water supplies. The relative risk
assessment again suggests that deep
well injection has a higher risk than the
other options based on this factor.
Movement of contamination into
USDWs has been confirmed or is
suspected at 9 of the 45 municipal
facilities that utilize Class I deep
injection in South Florida, as evidenced
by levels of nitrates and ammonia, as
well as significant changes in dissolved
solids concentrations. The other option
with a relatively high risk of
contaminating drinking water supplies
is aquifer recharge. Ocean outfalls and
surface water discharges pose a lower
risk of contaminating drinking water
supplies, for reasons given previously.
Relative to the other options,
however, ocean outfalls and surface
water discharges pose a higher risk of
people coming into direct contact with
the released contaminants in other
ways, such as by eating contaminated
fish, by swimming in contaminated
waters, and by participating in other
recreational activities. These same two
options also pose a risk of stimulating
algal blooms that could be harmful,
although this risk associated with
surface water discharges is mitigated
substantially by the removal of
wastewater nutrients prior to release to
surface waters in South Florida.
2. Ecological Health
Overall, the risk to surface water
ecosystems is low when treated
wastewater is managed by deep well
injection and aquifer recharge in South
Florida. The risk to surface water
ecosystems is also generally low when
treated wastewater is discharged
directly to surface waters. For all three
of these management options, however,
the potential for damage may be higher
where treated wastewater is released in
proximity to surface water that already
has impaired water quality, which is the
case for many surface water bodies in
South Florida. In these cases, the
nutrients that might enter impaired
waters could exacerbate existing -water
quality and ecological problems.
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23677
The risk to marine ecosystems is
obviously greatest for the ocean disposal
option. Ocean outfall monitoring data
from available studies indicate that, for
the most part, water quality standards
are met by most constituents at the edge
of the permitted mixing zone
(approximated by a circle with a 400-
meter radius), with the occasional
exception of nitrogen and some metals.
It is recognized, however, that effluent
plumes may well extend outside the
400-meter radius and that marine
organisms exposed in and around such
plumes can likewise travel farther
distances. Pathogenic microorganisms
in particular pose some concern,
because effluent discharged to the ocean
is not filtered and there is some
evidence to suggest that aquatic
organisms suffer from high
concentrations of such microorganisms.
The effects of pathogenic
microorganisms on aquatic animals
need to be better documented, as does
their concentration in ocean discharges
and resulting plumes.
Deep well injection could also pose a
risk to marine ecology if contaminants
can readily migrate and discharge to
offshore waters. However, the extent to
which this actually happens in South
Florida and poses a real threat in the
ocean is uncertain.
Two potential ecological effects of
particular concern, should surface or
ocean waters be sufficiently
contaminated, include harmful algal
blooms and bioconcentration of toxic
contaminants in the food web. Algal
blooms can cause a variety of toxic
symptoms in aquatic organisms
(including death) as well as nontoxic'
adverse effects such as clogging of gills
and smothering of coral reefs and
seagrass beds. Food web
bioconcentration of metals and other
contaminants can also cause of variety
of toxic effects.
Finally, the ocean discharge option
introduces the potential for the physical
destruction of coral reefs traversed by
discharge pipelines. The existing ocean
outfalls in South Florida range from 0.9
to 3.6 miles offshore. Any widening or
extension of existing pipelines leading
to these outfalls could impair or destroy
any nearby coral reefs. The same would
be true if new outfalls and pipelines are
constructed through coral reefs in the
future to accommodate increased
disposal needs.
E. What Are the Important Data or
Knowledge Gaps?
For all four wastewater management
options, the relative risk assessment
found that there is a lack of definitive
studies in South Florida that use a
physical or chemical tracer or indicator
to identify the source and transport
pathways of stressors detected in the
environment. Ocean discharge is the
only disposal option for which there is
a known tracer study proving the source
of stressor,s. In this study, a stable
isotope tracer indicated that nitrogen
was not b^ing taken up in any
significant amount by phytoplankton in
the vicinity of the South Florida ocean
outfalls. However, without more
•definitive tracer studies for each
wastewater management option, it is
difficult to assess the potential effects of
local conditions on the fate and
transport pf treated wastewater after
being released into the environment.
While results from ground water
monitoring around some Class I
municipal wells in South Florida
confirm that fluids have migrated out of
the permitted injection zone, the full
areal extent of USDW impact is not
known. This is not only because
available monitoring data are limited,
but also because the location and
connectivity of natural conduits for
fluid flow (fractures and solution
cavities hi the underground formation)
are difficult to predict.
Specifically for the deep well
injection and aquifer recharge options,
the fate aijid transport of pathogens in
South Florida's aquifers are not
completely understood. For example,
the rates of microbial survival,
inactivatipn, and transport are difficult
to predict, Also uncertain are the rates
of microbial straining or filtration by
geological materials under different
fluid flow scenarios, including porous
media and conduit flow. The fate and
transport of pathogens is especially
difficult to verify for deep well
injection, jeven with the most
sophisticated modeling or with
expensive! monitoring, since the
receiving formations are thousands of
feet underground.
Of particular relevance for the ocean
disposal option, there is a lack of
understanding regarding down-current
impacts,'risks to marine organisms
passing through the mixing zone, and
the potential for food web
bioconcentration. Potential long-term
ecological risks may exist inside and
outside the mixing zone, but due to a
lack of ongoing ecological monitoring
studies arpund any of the existing ocean
outfalls irl South Florida, there is no
information on actual biological
receptors or exposure pathways that
undoubtedly exist at the outfall sites.
The lack of such long-term monitoring
information makes it impossible to
confirm that there are no long-term or
cumulative ecological or biological
effects of discharged effluent.
With respect to surface discharges,
there is significant uncertainty regarding
the potential for food web
bioconcentration and the severity of
cumulative impacts caused by other
sources of the same chemical and
microbiological stressors contained in
treated municipal wastewater.
These other sources of contamination
include onsite sewage disposal systems,
non-point source runoff from
agricultural or urban areas, atmospheric
deposition, or other point sources. The
risks posed by surface water discharge
need to be put into overall context of the
cumulative risks posed by all sources of
stressors in order to gain a sense of their
relative importance.
Dated: April 17, 2003.
G. Tracy Mehan ffl,
Assistant Administrator for Water.
[FR Doc. 03-10269 Filed 5-2-03; 8:45 am]
BILLING CODE 6560-50-P
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