[Federal Register: May 5, 2003 (Volume 68, Number 86)]
[Proposed Rules]
[Page 23673-23677]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05my03-43]
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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.
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SUMMARY: On July 7, 2000, the Environmental Protection Agency (EPA)
[[Page 23674]]
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 in making 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
III. 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:
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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 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.
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. 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
[[Page 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 issue 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.
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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
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 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 and
incorporate data and information acquired through comprehensive
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.
Section III summarizes the major findings of the relative risk
assessment, which has been finalized. In a separate notice of data
availability published elsewhere in today's Federal Register, EPA
requests comment on how the relative risk assessment should inform the
final rulemaking on deep municipal injection wells in Florida.
III. Findings of the Relative Risk Assessment
The relative risk assessment offers comparisons of deep well
injection, ocean disposal, surface discharge, and aquifer recharge of
treated municipal wastewater in South Florida by considering several
factors important for determining risk. This section highlights how the
report addresses the following questions: (A) What level of treatment
and disinfection is provided? (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? (E)
What are the important data or knowledge gaps? The purpose of this
summary, the publication of the report, and this notice of availability
is to discharge fully EPA's responsibility to complete the relative
risk assessment mandated by Congress.
A. What Level of Treatment and Disinfection Is Provided?
Municipal wastewater managed by any of the four options studied in
South Florida receives secondary treatment, at a minimum. 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
provide disinfection, i.e., removal of microorganisms.
1. Deep Well Injection
All facilities that manage municipal wastewater by deep well
injection in Florida are required by Florida law to provide at least
secondary treatment of the wastewater prior to injection. In addition,
utilities that employ deep well injection must maintain disinfection
capability, but many do not disinfect treated effluent prior to
injection. For
[[Page 23676]]
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 more
stringent 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 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 Cryptosporidium, 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
Cryptosporidium 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., dechlorination), 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
(Cryptosporidium, 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 Cryptosporidium 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 Cryptosporidium
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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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 stressors. In this
study, a stable isotope tracer indicated that nitrogen was not being
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 of 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 in the
underground formation) are difficult to predict.
Specifically for the deep well injection and aquifer recharge
options, 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. The fate and
transport of pathogens is especially difficult to verify for deep well
injection, even 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 around any of the existing ocean outfalls
in 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 III,
Assistant Administrator for Water.
[FR Doc. 03-10269 Filed 5-2-03; 8:45 am]
BILLING CODE 6560-50-P