[Federal Register: May 5, 2003 (Volume 68, Number 86)]
[Proposed Rules]
[Page 23666-23673]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05my03-42]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 146
[FRL-7488-7]
Underground Injection Control Program--Revision of Underground
Injection Control Requirements for Class I Municipal Wells in Florida;
Notice of Data Availability
AGENCY: Environmental Protection Agency.
ACTION: Notice of data availability.
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SUMMARY: On July 7, 2000, the Environmental Protection Agency (EPA)
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. The 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. A separate document in today's
Federal Register announces the availability and summarizes the findings
of this relative risk assessment required by Congress. In this notice
of data availability, EPA solicits public comment on how information on
deep (Class I municipal) well injection in the relative risk assessment
should inform the Agency's action on the July 7, 2000, proposed rule.
DATES: Comments on this notice of 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 may be submitted
[[Page 23667]]
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, contact Nancy H. Marsh,
Ground Water & UIC Section, U.S. Environmental Protection Agency,
Region 4, 61 Forsyth Street, SW., Atlanta, GA 30303-8960 (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
A. Who are Regulated Entities?
B. Additional Docket Information
C. Will There Be Public Meetings?
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
III. Findings of the Relative Risk Assessment Pertaining to Deep
Well Injection
A. What Level of Treatment and Disinfection is Provided for Deep
Well Injection?
B. What Stressors Remain (After Treatment) That May Be a Concern
for Deep Well Injection?
C. What Exposure Pathways Are (Or May Be) of Significance for
Deep Well Injection?
D. What is the Overall Estimate of Risk for Deep Well Injection?
E. What Are the Important Data or Knowledge Gaps for Deep Well
Injection?
IV. Relevance of These Findings for the Final Rule for Class I
Municipal Wells in South Florida
A. Additional Wastewater Treatment Prior to Injection
B. Feasibility of a Hydrogeologic Demonstration
C. Some Deep Wells May Have Been Misclassified as Class I, When
They Are Actually Class V
V. Solicitation of Comment
I. General Information
A. Who Are Regulated 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:
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Category Examples of entities
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Municipalities and Local Government.... Class I municipal injection
wells disposing of domestic
wastewater effluent in certain
parts of Florida.
Private................................ Class I municipal injection
wells disposing of domestic
wastewater effluent in certain
parts of Florida.
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This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. This table lists the types of entities that EPA is now aware
could potentially be regulated by this action. Other types of entities
not listed in the table could also be regulated by this action. To
determine whether your injection well might be regulated, 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.
B. Additional Docket Information
When submitting written comments (see ADDRESSES section) please
submit an original and three copies of your comments and enclosures
(including any references). The record is available for inspection from
8 a.m. to 3:30 p.m. Eastern daylight-saving time, Monday through
Friday, excluding legal holidays, at the Environmental Protection
Agency, Region 4 Library (9th Floor), Sam Nunn Atlanta Federal Center,
61 Forsyth St., SW., Atlanta, GA 30303-8960. For information on how to
access Docket materials, please call 404-562-8190 and refer to the
Florida UIC docket.
C. Will There Be Public Meetings?
EPA plans to have public meetings in Florida during the comment
period. EPA will announce the dates, times and locations of those
public meetings in a subsequent Federal Register document.
II. 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 (SDWA). 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 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
additional requirements that provide adequate protection for USDWs. If
new requirements are not promulgated, owners and/or operators of wells
affected by the proposal would
[[Page 23668]]
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 facilities with
advanced wastewater treatment, nutrient removal, and high-level
disinfection.
EPA proposed two primary options for the additional requirements:
Option 1--Facilities must provide advanced wastewater treatment and
high-level disinfection with a demonstration that the injectate will
not cause a USDW to exceed any national primary drinking water
regulations in 40 CFR part 141 and other health-based standards (e.g.,
Federal or State health advisories approved by the UIC Program
Director, if a national primary drinking water regulation is not
available for specific pollutants); and Option 2--Facilities must
conduct an in-depth hydrogeologic demonstration that the injection
operation would not cause fluids that will migrate into the USDW to
exceed any national primary drinking water regulations in 40 CFR part
141 and other health-based standards and, if the demonstration is not
successful, must provide advanced treatment, as necessary, to ensure
that injectate will not cause a USDW to exceed any national primary
drinking water regulations in 40 CFR part 141 and other health-based
standards. This second option also proposed a provision whereby all
facilities qualifying for authorization to inject under this option
would be required to install advanced wastewater treatment and high-
level disinfection by 2015. The preamble to the proposal describes in
detail the history of domestic wastewater injection in Florida, along
with the features of Florida geology that have allowed some of that
injected wastewater to enter 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 this notice of data availability, as part of
the final action 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 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 adopted accordingly.
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\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 http://www.esd.ornl.gov/programs/ecorisk/tm186.pdf
.
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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
both assess the risks and allow comparisons. Individual risk
assessments were completed for each wastewater disposal option and the
risks associated with each were characterized. The risks and risk
factors identified through each option-specific disposal 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 from a variety of fields to review and incorporate
data and information acquired through exhaustive searches of the
relevant scientific research literature. Risk characterization for each
option included identifying and describing the associated risks, their
potential magnitude, and the potential effects on human and ecological
health. The relative risk assessment then described and compared risks
for all four wastewater management options. Finally, the relative risk
assessment was peer reviewed in accordance with the Agency's Peer
Review Handbook.
III. Findings of the Relative Risk Assessment Pertaining to Deep Well
Injection
The relative risk assessment offers comparisons of deep well
injection, ocean disposal, surface discharge, and aquifer recharge of
treated municipal wastewater in South Florida. Findings related to each
of these management options are highlighted in a separate notice in
today's Federal Register and presented in greater detail in the
relative risk assessment report. EPA is seeking comment in sections IV
and V below on how these findings should inform the final rulemaking on
Class I municipal wells in Florida. To provide background and context
for those following sections, the remainder of this section summarizes
how the relative risk assessment addresses five key questions
specifically related to deep well injection.
A. What Level of Treatment and Disinfection Is Provided for Deep Well
Injection?
All facilities that manage municipal wastewater by deep well
injection in Florida are required to provide, at a minimum, secondary
treatment of the wastewater prior to injection. Secondary treatment
comprises biological removal of dissolved organic and inorganic matter,
commonly through such methods as activated sludge and trickling filter
processes. By itself, secondary treatment does not remove
microorganisms by either disinfection (through the addition of
chlorine, for example) or filtration.
[[Page 23669]]
Utilities that employ deep well injection in South Florida must
maintain disinfection capability, but many do not disinfect treated
effluent prior to injection. For example, treatment of wastewater that
is injected by Class I municipal wells in Dade 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 reclaimed water standards before being
discharged into Class I municipal wells, because the Class I 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 and a variety of techniques to address
pathogenic microorganisms, including filtration and high-level
disinfection.
B. What Stressors Remain (After Treatment) That May Be a Concern for
Deep Well Injection?
``Stressors'' include chemical or biological agents that may cause
adverse effects if exposure levels are high enough. They may pose a
risk to human health and/or ecological health if they reach receptors
(USDWs, drinking water supply wells, surface waters) at sufficiently
high concentration levels. EPA has included USDW's as a receptor
because of the Agency's responsibility under the Safe Drinking Water
Act to prescribe regulations for State underground injection programs,
like Florida's, that contain minimum requirements to prevent
underground injection from endangering USDW's.
In cases where injectate has received secondary treatment only,
bacteria, viruses, and protozoa (e.g., Cryptosporidium and Giardia) are
generally not inactivated prior to deep well injection in South
Florida. In cases, such as Pinellas County, where injectate has been
treated to reclaimed water standards, viruses and bacteria have likely
been largely inactivated through disinfection and protozoa have been
largely removed through filtration.
Disinfection (or chlorination) by-products such as trihalomethanes
may also be present in some wastewater, although no data are available
to suggest that such by-products are a serious concern for deep well
injection or any of the other wastewater management options studied in
South Florida. EPA would not expect such by-products to be present in
wastewaters that have not undergone basic disinfection, as is often the
case for Class I injectate.
Nutrients are potential ecological stressors for deep well
injection, assuming the injected wastewater contains significant
quantities of nutrients and assuming the injected wastewater is able to
migrate underground and discharge into the ocean or into other surface
water bodies. Nutrients can potentially stimulate production of algae,
which can lead to adverse side effects such as eutrophication. Nitrogen
is the primary nutrient concern for Class I injection, because of its
mobility in ground water. Nitrogen is also the primary nutrient of
concern if it migrates to the ocean, because it is generally the
limiting nutrient for algae production in the ocean. Phosphorus is of
less concern for underground injection because it tends to adsorb
quickly to sediment or soil.
C. What Exposure Pathways Are (or May Be) of Significance for Deep Well
Injection?
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).
There are documented impacts to USDWs resulting from deep well
injection in South Florida, which raise concerns about potential human
exposures via the drinking water pathway. Beginning in the late 1980s,
ground water monitoring wells at 18 of the 45 municipal facilities that
utilize Class I deep well injection in South Florida began to detect
the movement of fluid outside of the permitted injection zones.
Movement of effluent into USDWs either has been confirmed or is
suspected at nine facilities, as evidenced by levels of nitrates and
ammonia, as well as significant changes in dissolved solids
concentrations.
Contaminants released by deep well injection can migrate through
the subsurface and discharge into marine and/or surface waters, where
they could pose risk via other pathways if loadings were sufficiently
large. Such subsurface transport is especially a concern where
contaminants can migrate relatively rapidly and with relatively little
attenuation through preferential flow paths (fractures, faults, and
solution cavities) common in the carbonate rocks in South Florida.
Potential concerns associated with injectate migrating into the ocean
or other surface water bodies could include the risk of ecological
damage as well as the risk of human exposure to contaminants through
such recreational activities as fishing, swimming, and boating.
D. What Is the Overall Estimate of Risk for Deep Well Injection?
The human health risks associated with deep well injection of
treated municipal wastewater in South Florida are generally low.
Several factors affect risk levels at particular sites.
The degree of wastewater treatment, and in particular the level of
disinfection and filtration of pathogenic microorganisms (e.g.,
Cryptosporidium, Giardia), is one such factor. Risks are lower when
wastewater has been treated to remove microorganisms. For wastewater
that has received only secondary treatment, risk would be high in
situations where the injectate migrates through fractures, faults, and
solution cavities and lower in situations where the injection is
dominated by porous media flow, characterized by long travel times to
current or potential drinking water sources, and flows through 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 and
over what time horizon. The record shows that such contamination of
drinking water supplies or USDWs is a possibility as a result of the
movement of fluid found at some injection facilities. In some cases,
the time frames for fluid to potentially reach USDWs are short enough
that treatment of injectate (i.e., inactivation, filtration) may be
warranted.
Overall, the risk to surface water ecosystems is low when treated
wastewater is managed by deep well injection in South Florida. 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. The dynamics
of potential fluid movement from UIC wells to surface waters is still
not well understood, however, at present there is no evidence of
contamination of surface water by Class I injectate.
Deep well injection could also pose a risk to marine ecology if
contaminants readily migrate and discharge to offshore waters. However,
whether this actually happens in South Florida, and whether it poses a
real threat in the ocean, is unknown. Given, however, that direct
discharge of effluent which has received only secondary treatment and
basic disinfection to the ocean
[[Page 23670]]
appears to pose little risk due to rapid dilution, it is unlikely that
seepage from ground water to the ocean would pose a significant risk.
E. What Are the Important Data Or Knowledge Gaps for Deep Well
Injection?
In conducting the relative risk assessment, EPA found that there is
a lack of definitive studies in South Florida that use a physical or
chemical tracer or indicator to show whether stressors detected in
aquifers come from treated wastewater managed by deep well injection,
and if so, by what likely contaminant transport pathways (porous versus
conduit flow). In addition, without more definitive tracer studies, it
is difficult to assess the potential effects of local geochemical
conditions on the fate and transport of injected treated wastewater.
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
contamination 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 in the underground formations) are difficult to predict.
The fate and transport of pathogens in South Florida's aquifers are
not completely understood. For example, the rates of microbial
survival, inactivation, 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. Even with the most sophisticated
modeling, or with expensive monitoring, this information is difficult
to verify since the formations are thousands of feet underground. There
is also insufficient data at present on the presence and viability of
pathogens in injectate that has migrated out of the injection zone.
However, the presence of coliform bacteria in injectate that has
migrated, a long accepted indicator of the presence of sewage,
indicates the likely presence of pathogenic microorganisms.
IV. Relevance of These Findings for the Final Rule for Class I
Municipal Wells in South Florida
EPA requests comment on how the findings from the relative risk
assessment, and identified data gaps, help inform the final regulatory
action on the July 7, 2000, proposal. EPA specifically requests comment
on the three issues discussed below.
A. Additional Wastewater Treatment Prior to Injection
EPA believes the following findings from the relative risk
assessment are relevant to the question of the extent to which
additional treatment may be needed for Class I injectate that has a
potential to reach USDWs.
1. Wastewater that does not undergo disinfection contains viruses
and pathogenic bacteria and protozoa that have not been inactivated.
Although the fate and transport of these pathogens in South Florida's
subsurface is not well known, monitoring and modeling data suggest
that, at some sites, fluid may migrate at rates that are sufficient to
transport active and infective pathogens into USDWs. For example, using
first order analytical modeling with conservative parameters and
assuming flow is dominated by bulk flow through preferential flow
paths, travel times to the base of the USDW of 170 days, 14 years, and
86 years have been estimated for Pinellas, Dade, and Brevard Counties
respectively. There is significant uncertainty as to how long the
viruses, protozoa, and bacteria will remain alive and to what extent
they may affect existing and future sources of drinking water, although
it is expected that significant attenuation and die-off would occur in
the deep subsurface over long travel times. The limited data that are
currently available show one-log (90%) inactivation rates in aquatic
media ranging from 40 to 200 days for Cryptosporidium, 6 to 50 days for
bacteria, and 1 to 30 days for viruses. This suggests that pathogen
contamination would likely be a concern in areas where travel times are
potentially short (e.g., Pinellas County). For such areas, additional
treatment (e.g., primary treatment, coagulation, settling, filtration,
and high-level disinfection) would likely be needed to inactivate,
remove, or greatly reduce pathogens in order to increase the level of
protection for current and future sources of drinking water. (As noted
above, wastewater in Pinellas County is already treated to reclaimed
water standards, which include both disinfection and filtration.)
Additional treatment beyond secondary may also be appropriate to
address pathogenic microorganisms in cases where injection of large
volumes of wastewater increases the uncertainty regarding the areal
extent of fluid movement and travel times for fluid to potentially
reach USDWs.
2. Insufficient confinement is evident at some facilities and
locations. At nine facilities, there is either confirmed or suspected
contamination of USDWs as a result of the movement of fluid from
designated injection zones. This is a violation of Federal and State
Class I UIC requirements, which prohibit any contaminants from entering
USDWs. At nine other facilities, there is evidence of movement outside
of the injection zone, though not yet into USDWs. Monitoring reports
from some facilities suggest that fluid movement has resulted in
fluctuations in total dissolved solids (TDS) concentrations and less
pronounced changes in the concentrations of other potential stressors
(e.g., fecal coliform, nitrate, ammonia, and total Kjeldahl nitrogen).
Such fluid may have the potential to contaminate future sources of
drinking water and place existing public and private water supplies at
risk.
3. The full areal extent of fluid movement is not known. Nearly 500
million gallons per day (mgd) are disposed of through deep well
injection at 42 sites in South Florida, with rates for individual wells
ranging from less than 1 to more than 100 million gallons per day
(mgd). While the dynamics of horizontal movement at any of these 42
sites of this quantity of water are not well understood, there is some
evidence that water with the potential to reach USDWs (due to
inadequate confinement) may not travel far. The first-order analytical
modeling results presented in the relative risk assessment show
horizontal travel distances at the surface ranging from 0.1 to 1.6
miles assuming rapid (bulk) vertical flow, and ranging from 1.2 to 16
miles assuming slow (porous media) flow. Note that a travel distance of
16 miles is modeled to occur only under a very long time horizon (1,188
years). Two members of EPA's External Peer Review Panel expressed
concern, however, regarding the feasibility of using numerical models
to assess the pattern of flow in and around the discharge zone (known
as the Boulder zone), and to account for several trillion gallons of
treated municipal wastewater that has been injected into the Boulder
zone since the inception of Florida's Class I UIC program. These Panel
members also pointed out that the risk could be significantly higher to
USDWs than the modeling calculations that assumed porous media flow
suggest, due to large uncertainties that were not accounted for in this
modeling. In response to these concerns, EPA developed a second model
assuming bulk flow through preferential flow paths, with travel times
for injectate to reach USDWs and drinking water wells that were an
order
[[Page 23671]]
of magnitude shorter than the porous media flow model. EPA believes,
and the reviewers agreed, that this second model largely addresses the
concerns raised, but recognizes that significant uncertainty regarding
the dynamics of underground fluid movement remain.
4. The location and connectivity of natural conduits for flow
(i.e., fractures, faults, and solution cavities) are unknown, although
their existence is well known by the type of rock present (e.g.,
limestone) and confirmed by logs during deep well construction. Where
such conduits are present, they may contribute to rapid migration of
injected fluids or displaced formation water, with little attenuation
of contaminant concentrations. Furthermore, such conduits may result in
unpredictable patterns of movement in the subsurface. The relative risk
assessment attempts to simulate such flows on a regional (not site-
specific) basis using a first order analytical model with conservative
parameter assumptions. However, there is significant uncertainty in
these results.
B. Feasibility of a Hydrogeologic Demonstration
Option 2 proposed on July 7, 2000, (as described above) would allow
facilities operating Class I municipal wells that have caused or may
cause fluid movement in South Florida to continue injection if they
perform a detailed hydrogeologic demonstration showing that injection
will not cause fluids to migrate and cause USDWs to exceed any national
primary drinking water regulations in 40 CFR part 141, and other
health-based standards. Where this demonstration cannot be made, Option
2 would require facilities to provide additional treatment as necessary
to address contaminants of concern and ensure that the continued
injection does not endanger USDWs. All facilities qualifying for
authorization to inject in accordance with Option 2 would be required
to have advanced wastewater treatment and high-level disinfection in
place by the year 2015. This requirement to phase in additional
treatment by 2015 was intended to provide municipalities with more time
to provide additional treatment if the municipality could conduct a
successful hydrogeologic demonstration.
EPA believes the following relative risk assessment findings are
relevant for assessing the feasibility of conducting a credible
detailed hydrogeologic demonstration, as proposed under Option 2.
1. As noted in the preceding section, the specific location,
extent, and connectivity of natural conduits for flow are unknown and
unpredictable in the South Florida areas targeted by the proposal.
Therefore, some of the key parameter values that would be used in
ground water modeling may be highly uncertain, and this may lead to a
broad range of predicted results for the location and movement of the
injected fluid. The relative risk assessment attempted to address this
issue on a regional (not site specific) basis by using first order
analytical methods to modeling bulk/preferential flow. This may or may
not be practicable for site-specific numerical modeling.
2. The ground water monitoring wells (or networks of monitoring
wells) at most deep well facilities in South Florida are sufficient
only for the purpose of providing an early warning of fluid movement.
Typically, ground water monitoring networks are used at waste
management facilities (e.g., hazardous waste landfills) to detect and
characterize the movement of relatively small volumes of contaminants
in shallow ground water. No deep well municipal waste disposal
facilities in South Florida have designed, constructed, and implemented
ground water monitoring programs capable of describing the full areal
extent of fluid movement, especially where natural conduits for flow
are present. In addition, few facilities perform extensive monitoring
between the base of the lowermost USDWs and the shallower surficial
aquifers. As noted above, however, modeling results suggest that the
areal extent of contamination that reaches the surface rapidly through
preferential flow may be limited (up to a few miles), although there is
significant uncertainty in these results due to the volumes of fluid
being injected and the possibility of fairly rapid horizontal movement
in the Boulder zone below the USDW, which was not explicitly modeled.
3. It is unclear whether it would be practicable to provide enough
additional ground water monitoring wells to provide the information
needed to demonstrate that fluid movement is not occurring and USDWs
are not being contaminated at sites where natural conduits for flow
exist. Because flow could well progress at different rates in different
directions, monitoring results for well locations at such sites would
not necessarily be representative of conditions at unmonitored
locations. Furthermore, there could be concern about the installation
of many monitoring wells to examine a particular site, because they may
penetrate rock and other materials that are otherwise barriers to fluid
movement. If such monitoring wells are constructed or managed
improperly, they could present man-made conduits for fluid movement.
C. Some Deep Wells May Have Been Misclassified as Class I, When They
Are Actually Class V
Given the extent of fluid movement documented at some sites, as
well as information concerning the geology and the construction of some
municipal wells in South Florida, it is possible that some wells may
have been misclassified as Class I when they are actually Class V.
According to the Federal UIC regulations, Class I wells ``inject fluids
beneath the lowermost formation containing, within one quarter mile of
the well bore, an underground source of drinking water'' (40 CFR
144.6(a)(2)). Class V wells are defined as wells that are not included
in Class I, II, III, or IV. Typically, Class V wells release non-
hazardous fluids into or above formations containing USDWs.
Separate from the issue of how Class I and Class V wells are
defined, the Federal Class I and Class V UIC programs differ in their
basic approach to protecting USDWs. The basic standard of protection in
the Class I program is to ensure that there is no movement of any
contaminant into USDWs. This standard is achieved through a Class I
regulatory program that focuses on the development and enforcement of
stringent permit requirements, including, but not limited to, criteria
for well siting, construction, and operation and maintenance. A key
component of the Class I program is ensuring that adequate confinement
exists between the permitted injection zone and USDWs at a given site.
Since most Class V wells release fluids either directly into or
above USDWs, they by definition cause the movement of fluid, which may
contain contaminants, into or above USDWs. Therefore, the basic
standard of protection in the Class V program is to prevent any
contaminants in the fluid from endangering USDWs. Protection efforts in
the Class V program mainly focus on regulating and monitoring injectate
quality to ensure that the movement of injected fluid will not contain
any contaminants that may endanger USDWs. This standard is achieved
through inventory and assessment requirements, additional reporting
requirements, closure requirements, and other requirements (possibly
including permitting requirements) believed by UIC program staff to be
necessary to protect drinking water supplies.
The failures of confinement that have been documented at some
municipal
[[Page 23672]]
well sites in South Florida, which are most likely attributable to the
presence of natural conduits for flow in the subsurface, suggest that
the injection zones used by these municipal wells are not sufficiently
separated from overlying USDWs by a confining layer to prevent fluid
movement upward into the USDW. The injectate from these wells is,
therefore, entering into a USDW. Injection zones in South Florida often
share a ``degree of lithologic homogeneity'' (as specified in the 40
CFR 144.3 definition of ``formation'') with the overlying ``confining
layers'' and USDWs (i.e., each consists of carbonate sequences). In
some locations, the injection zones, ``confining layers,'' and USDWs
may be said to exist within one formation. It is possible that a well
injecting at such a location may not be appropriately classified as a
Class I well.
Information collected for the relative risk assessment raises a
question as to whether certain South Florida municipal disposal wells
should have been classified as Class V at the time they were first
permitted. In particular, all of the lithologic units of the upper
Floridan Aquifer in Pinellas County and the lower Floridan Aquifer in
Miami-Dade consist of limestone and dolomite that have shown evidence
of solution cavities and fractures. These natural conduits for fluid
flow raise a question as to whether lithologic units in these aquifers
are effective confining layers and whether the injection zones and
overlying USDWs are in different and distinct formations, as they were
believed to be when the wells were originally sited, constructed, and
permitted as Class I wells.
V. Solicitation of Comment
In the July 7, 2000, proposed rule (65 FR 42234), EPA proposed
regulatory options that would allow for continued wastewater injection
by existing Class I municipal wells that have caused or may cause fluid
movement in specific areas of Florida. The relative risk assessment
described in this notice and in a companion notice appearing elsewhere
in today's Federal Register contains some new information regarding the
potential risks of deep well injection of municipal wastewater in South
Florida. The Agency is soliciting comment on whether and how the
findings of the relative risk assessment should inform the Agency in
developing the final rule for wells currently classified as Class I
deep municipal wells in South Florida.
In addition to the issues discussed above, the Agency is soliciting
comment on the following three issues:
1. The Agency solicits comment on an alternative option for
defining the appropriate level of wastewater treatment required for
continued injection in deep municipal wells in South Florida. The
proposed rule solicited comment on four levels of advanced wastewater
treatment, nutrient removal, and high-level disinfection that, under
Option 1 and by the year 2015 under Option 2, would be required of
facilities operating wells that have caused or may cause fluid
movement. The alternatives proposed under Option 1 were: (1) Treatment
to 10-24 mg/l biochemical oxygen demand (BOD) with disinfection; (2)
treatment to 10-24 mg/l BOD with disinfection and nutrient removal; (3)
treatment to <10 mg/l BOD with disinfection; and (4) treatment to <10
mg/l BOD with disinfection and nutrient removal. These levels were used
by the 1996 Clean Water Needs Survey Manual to delineate and cost
levels of advanced treatment. To achieve high-level disinfection, the
proposal said owners and/or operators must allow the wastewater to
remain in contact with at least 1.0 mg/l of free chlorine for at least
15 minutes of contact with no fecal coliform.
Several commenters suggested that the proposed standards for BOD
removal are inappropriate for the protection of ground water for the
purpose of protecting human health. These commenters stated that BOD
levels are typically used for the protection of ecological values in
surface water, not the protection of human health associated with
drinking ground water. The commenters also pointed out that the main
stressor of concern in the injectate is pathogens, not BOD. Separately,
commenters noted that EPA's proposed definition of high-level
disinfection differs from the State of Florida's definition of the same
term in Rule 62-600.440, F.A.C., which commenters thought would result
in confusion. Other commenters suggested that any new EPA wastewater
treatment requirements should be consistent with corresponding state
requirements. For example, Florida's regulations for waste treatment
and disinfection applicable to reclaimed water that may come into human
contact (Rule 62-610.460, F.A.C.) and ground water disposal by
underground injection in Class V wells (Rule 62-600.540(2) and (Rule
62-600.440(5), F.A.C.) are similar to the more advanced levels of
treatment envisioned under Option 1 of the proposed rule that require
filtration before disinfection. As stated in the Florida regulations,
by removing TSS before disinfection, filtration serves to increase the
ability of the disinfection process to inactivate viruses and other
pathogens. Filtration also serves as the primary barrier for removal of
protozoan pathogens (Cryptosporidium, Giardia, and others).
Based on these comments, EPA is now considering and soliciting
comments on prescribing wastewater treatment requirements in language
that differs from the four alternatives proposed on July 7, 2000 but
conforms with relevant state requirements. The Agency is not asking for
additional comment on the four levels of advanced wastewater treatment,
nutrient removal, and disinfection described in the proposal. Under
this alternative, the Agency would simply adopt, in lieu of the four
standards in the proposal, the Florida standards in Rule 62-610.460,
F.A.C. (for waste treatment and disinfection applicable to reclaimed
water that may come into contact with people) or the standards in Rule
62-600.540(2) and Rule 62-600.440(5), F.A.C. (for ground water disposal
by underground injection in Class V wells). Specifically, EPA would
require advanced wastewater treatment that results in treated water
meeting, at a minimum, secondary treatment and high-level disinfection
as defined in the Florida regulations. Also, filtration would be
required for TSS control prior to disinfection, which would specify
that the treated wastewater not contain more than 5.0 mg/l of TSS
before the application of the disinfectant. EPA believes that this
treatment standard might offer some important advantages over the
alternatives proposed before. In particular, it might better address
the risks associated with pathogens, and it would be consistent with
the standards already adopted and implemented in Florida for reclaimed
water and wastewater disposed of through Class V injection wells, which
are part of domestic wastewater treatment systems.
The Agency asks commenters if this standard for advanced treatment
and high-level disinfection should be specified in the final rule and
requests that commenters describe the type of treatment that would be
necessary to achieve the performance standards (i.e., national primary
drinking water regulations and other health-based standards). Although
the Agency believes that the design and construction costs of this
option are equivalent to those for the earlier proposed treatment
options that required treated effluent concentration of less than 10
milligrams per liter of BOD, the Agency requests that
[[Page 23673]]
commenters provide any information they have on the costs of this
option.
2. The proposed rule solicited comment on a second option, Option
2, that would allow facilities operating wells that have caused or may
cause fluid movement to conduct hydrogeologic demonstrations to show
that injection will not cause fluids that exceed any national primary
drinking water regulations in 40 CFR part 141 and other health-based
standards to enter any USDW. Option 2 would also require well owners
and/or operators that cannot make this demonstration to provide
additional treatment as needed to address contaminants of concern.
Further, Option 2 requires advanced wastewater treatment and high-level
disinfection to be in place by 2015. The Agency requests comment on
whether the findings from the relative risk assessment, specifically
those regarding deep well injection, suggest anything regarding the
practicability and feasibility of this approach. Should facilities be
granted the opportunity to conduct hydrogeologic demonstrations (and
expend the resources and funds necessary) despite the inherent
difficulties and uncertainties regarding the extent, location, and
connectivity of possible natural conduits for flow identified in the
relative risk assessment? If facilities should be granted this
opportunity, how should the UIC director in his/her review of a
demonstration, address the technical difficulties in determining the
extent of the contamination, and the location of conduits for flow into
USDWs, so that the demonstration may be deemed adequate? Given the
uncertainty that accompanies the effort to analytically or numerically
simulate the fate and transport of fluid and stressors in South
Florida's deep underground environment, EPA solicits comment on ways
that a satisfactory hydrogeological demonstration can be conducted.
Finally, the proposed rule included a ``sunset provision'' (requiring
advanced wastewater treatment and high-level disinfection by 2015) as
part of this option even if protection of USDWs is being demonstrated.
EPA requests comment on an alternative that would allow the State
Director to authorize updated hydrogeologic assessments and defer
treatment requirements beyond 2015 if the assessments continued to
demonstrate adequate protection of the USDW.
3. One option to address the fluid movement that has occurred,
while also preventing the endangerment of USDWs, might be to promulgate
new Class V requirements specific to deep municipal wells in South
Florida. In a 1999 stakeholders meeting, the Agency discussed two
options for reclassifying these wells as Class V. One of these options
would reclassify the wells based on a determination that the wells no
longer meet the regulatory definition of a Class I well. Another option
would involve converting the wells to Class V by physically altering
the wells so that they inject directly into or above formations
containing the lowermost USDW. Two other options discussed at the
stakeholders meeting were (1) to make no regulatory change (and enforce
the existing requirements) and (2) to amend the Class I regulations to
address the fluid movement issues. EPA ultimately proposed this last
option and published proposed revisions to the Class I requirements.
EPA stated in the preamble to the July 7, 2000, proposal (65 FR 42237):
``The Agency is not planning to allow reclassification unless the well
was misclassified in the first instance. Misclassification might have
occurred if the well did not originally meet the definition of a Class
I well. The facility could demonstrate this if new information has
become available that proves that the well originally was injecting
into a USDW and therefore would meet the definition of a Class V
well.''
EPA is now reconsidering the reclassification option.
Reclassification could be accomplished without any regulatory changes
to the Class I definitions or the Class I ``no fluid movement''
requirements. Following publication of this NODA and receipt of
comments on this option, EPA, if it chose the reclassification option,
would publish final revisions to the Class V regulations that include
the same operating conditions that EPA would have promulgated as
revisions to the Class I regulations. This option is contrasted with
the approach discussed more fully in the July 7, 2000, proposal to keep
the wells as Class I and add the necessary operating conditions to the
Class I regulations. Either approach could be used to place the same
operating conditions on continued injection activities and provide
identical protection to USDWs.
In addition, EPA is considering whether there might be a need to
promulgate the operating conditions under consideration as final
regulations under both the Class I and Class V regulatory frameworks.
This might be necessary in order to ensure that the new requirements
apply to all municipal waste disposal wells in South Florida that cause
or may cause fluid movement into a USDW, regardless of whether it is
determined that a particular well may be reclassified as Class V or
must remain in Class I. EPA invites comment on the need for
incorporating the proposed operating conditions into either, or both,
the Class I and Class V regulations. EPA notes that the costs of
installing a specified level of treatment would be the same, regardless
of whether a particular well is classified as Class I or Class V.
One potential advantage of the reclassification option is that it
could correct any previous misclassification of wells in South Florida.
A potential disadvantage of the reclassification option is that it
could lead to reclassification requests associated with other wells in
other parts of the country and could limit the flexibility of local
permit writers to make classification determinations.
In summary, with regard to reclassification of Class I wells, the
Agency requests comment on whether the findings from the relative risk
assessment, specifically those regarding deep well injection, suggest
that some South Florida wells may have been misclassified as Class I
wells? Do the findings suggest that some wells in South Florida may, in
fact, discharge directly to (and not below) formations containing a
USDW? Do the findings suggest that this misclassification should be
accepted for the entire group of South Florida municipal wells, or only
a subset? Should the regulatory requirements under consideration be
promulgated under provisions for Class I or Class V? If
reclassification is only appropriate for some of the covered South
Florida wells, should the regulatory requirements under consideration
be promulgated under provisions for both Class I and Class V.
Dated: April 17, 2003.
G. Tracy Mehan III,
Assistant Administrator for Water.
[FR Doc. 03-10268 Filed 5-2-03; 8:45 am]
BILLING CODE 6560-50-P