National Primary Drinking Water Regulations: Long Term 1 Enhanced Surface Water Treatment and Filter Backwash Rule

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Federal Register › Vol. 65 › 65 FR 19046

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ENVIRONMENTAL PROTECTION AGENCY 40 CFR Parts 141 and 142 [WH-FRL-6570-5] RIN 2040-AD18 National Primary Drinking Water Regulations: Long Term 1 Enhanced Surface Water Treatment and Filter Backwash Rule AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

In this document, EPA is proposing the Long Term 1 Enhanced Surface Water Treatment and Filter Backwash Rule (LT1FBR). The purposes of the LT1FBR are to: Improve control of microbial pathogens in drinking water, including Cryptosporidium , for public water systems (PWSs) serving fewer than 10,000 people; prevent increases in microbial risk while PWSs serving fewer than 10,000 people control for disinfection byproducts, and; require certain PWSs to institute changes to the return of recycle flows within the treatment process to reduce the effects of recycle on compromising microbial control. Today's proposal addresses two statutory requirements of the 1996 Safe Drinking Water Act (SDWA) Amendments. First, it addresses the statutory requirement to establish a Long Term Final Enhanced Surface Water Treatment Rule (LTESWTR) for PWSs that serve under 10,000 people. Second, it addresses the statutory requirement to promulgate a regulation which “governs” the recycle of filter backwash within the treatment process of public utilities.

Today's proposed LT1FBR contains 5 key provisions for surface water and ground water under the direct influence of surface water (GWUDI) systems serving fewer than 10,000 people: A treatment technique requiring a 2-log (99 percent) Cryptosporidium removal requirement; strengthened combined filter effluent turbidity performance standards and new individual filter turbidity provisions; disinfection benchmark provisions to assure continued microbial protection is provided while facilities take the necessary steps to comply with new disinfection byproduct standards; inclusion of Cryptosporidium in the definition of GWUDI and in the watershed control requirements for unfiltered public water systems; and

turbidity performance standards and new individual filter turbidity provisions; disinfection benchmark provisions to assure continued microbial protection is provided while facilities take the necessary steps to comply with new disinfection byproduct standards; inclusion of Cryptosporidium in the definition of GWUDI and in the watershed control requirements for unfiltered public water systems; and requirements for covers on new finished water reservoirs.

Today's proposed LT1FBR contains three key provisions for all conventional and direct filtration systems which recycle and use surface water or GWUDI: A provision requiring recycle flows to be introduced prior to the point of primary coagulant addition; a requirement for systems meeting criteria to perform a one-time self assessment of their recycle practice and consult with their primacy agency to address and correct high risk recycle operations; and a requirement for direct filtration systems to provide information to the State on their current recycle practice.

The Agency believes implementing the provisions contained in today's proposal will improve public health protection in two fundamental ways. First, the provisions will reduce the level of Cryptosporidium in filtered finished drinking water supplies through improvements in filtration and recycle practice resulting in a reduced likelihood of outbreaks of cryptosporidiosis. Second, the filtration provisions are expected to increase the level of protection from exposure to other pathogens ( i.e. Giardia or other waterborne bacterial or viral pathogens). It is also important to note that while today's proposed rule contains new provisions which in some cases strengthen or modify requirements of the 1989 Surface Water Treatment Rule, each public water system must continue to comply with the current rules while new microbial and disinfectants/disinfection byproducts rules are being developed

Giardia or other waterborne bacterial or viral pathogens). It is also important to note that while today's proposed rule contains new provisions which in some cases strengthen or modify requirements of the 1989 Surface Water Treatment Rule, each public water system must continue to comply with the current rules while new microbial and disinfectants/disinfection byproducts rules are being developed. In conjunction with the Maximum Contaminant Level Goal (MCLG) established in the Interim Enhanced Surface Water Treatment Rule, the Agency developed a treatment technique in lieu of a Maximum Contaminant Level (MCL) for Cryptosporidium because it is not economically and technologically feasible to accurately ascertain the level of Cryptosporidium using current analytical methods.

DATES:

The Agency requests comments on today's proposal. Comments must be received or post-marked by midnight June 9, 2000. Comments received after this date may not be considered in decision making on the proposed rule.

ADDRESSES:

Send written comments on today's proposed rule to the LT1FBR Comment Clerk: Water Docket MC 410, W-99-10, Environmental Protection Agency 401 M Street, S.W., Washington, DC 20460. Please submit an original and three copies of comments and enclosures (including references).

Those who comment and want EPA to acknowledge receipt of their comments must enclose a self-addressed stamped envelope. No facsimiles (faxes) will be accepted. Comments may also be submitted electronically to ow-docket@epamail.epa.gov. For additional information on submitting electronic comments see Supplementary Information Section.

Public comments on today's proposal, other major supporting documents, and a copy of the index to the public docket for this rulemaking are available for review at EPA's Office of Water Docket: 401 M Street, SW., Rm. EB57, Washington, DC 20460 from 9:00 a.m. to 4:00 p.m., Eastern Time, Monday through Friday, excluding legal holidays

ting electronic comments see Supplementary Information Section.

FOR FURTHER INFORMATION CONTACT:

Technical inquiries on the rule should be directed to Jeffery Robichaud at 401 M Street, SW., MC4607, Washington, DC 20460 or (202) 260-2568. For general information contact the Safe Drinking Water Hotline, Telephone (800) 426-4791. The Safe Drinking Water Hotline is open Monday through Friday, excluding federal holidays, from 9:00 a.m. to 5:30 p.m. Eastern Time.

SUPPLEMENTARY INFORMATION:

Entities potentially regulated by the LT1FBR are public water systems (PWSs) that use surface water or ground water under the direct influence of surface water (GWUDI). The recycle control provisions are applicable to all PWSs using surface water or GWUDI, regardless of the population served. All other provisions of the LT1FBR are only applicable to PWSs serving under 10,000 people. Regulated categories and entities include:

Category Examples of regulated entities Industry Public Water Systems that use surface water or ground water under the direct influence of surface water. State, Local, Tribal or Federal Governments Public Water Systems that use surface water or ground water under the direct influence of surface water. This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be regulated by the LT1FBR. This table lists the types of entities that EPA is now aware could potentially be regulated by this rule. Other types of entities not listed in this table could also be regulated

use surface water or ground water under the direct influence of surface water. This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be regulated by the LT1FBR. This table lists the types of entities that EPA is now aware could potentially be regulated by this rule. Other types of entities not listed in this table could also be regulated. To determine whether your facility is regulated by this action, you should carefully examine the definition of public water system in § 141.3 of the Code of Federal Regulations and applicability criteria in §§ 141.76 and 141.501 of today's proposal. If you have questions regarding the applicability of the LT1FBR to a particular entity, consult the person listed in the preceding section entitled FOR FURTHER INFORMATION CONTACT .

Submitting Comments

Send an original and three copies of your comments and enclosures (including references) to W-99-10 Comment Clerk, Water Docket (MC4101), USEPA, 401 M Street, SW., Washington, D.C. 20460. Comments must be received or post-marked by midnight June 9, 2000. Note that the Agency is not soliciting comment on, nor will it respond to, comments on previously published regulatory language that is included in this document to ease the reader's understanding of the proposed language.

To ensure that EPA can read, understand and therefore properly respond to comments, the Agency would prefer that commenters cite, where possible, the paragraph(s) or sections in the proposed rule or supporting documents to which each comment refers. Commenters should use a separate paragraph for each issue discussed.

Electronic Comments

ich each comment refers. Commenters should use a separate paragraph for each issue discussed.

Electronic Comments

Comments may also be submitted electronically to ow-docket@epamail.epa.gov. Electronic comments must be submitted as an ASCII, WP5.1, WP6.1 or WP8 file avoiding the use of special characters and form of encryption. Electronic comments must be identified by the docket number W-99-10. Comments and data will also be accepted on disks in WP 5.1, 6.1, 8 or ASCII file format. Electronic comments on this document may be filed online at many Federal Depository Libraries.

The record for this rulemaking has been established under docket number W-99-10, and includes supporting documentation as well as printed, paper versions of electronic comments. The record is available for inspection from 9 a.m. to 4 p.m., Monday through Friday, excluding legal holidays at the Water Docket, EB 57, USEPA Headquarters, 401 M Street, SW., Washington, D.C. For access to docket materials, please call (202) 260-3027 to schedule an appointment.

List of Abbreviations Used in This Document

ASCE American Society of Civil Engineers ASDWA Association of State Drinking Water Administrators ASTM American Society for Testing Materials AWWA American Water Works Association AWWARF American Water Works Association Research Foundation °C Degrees Centigrade CCP Composite Correction Program CDC Centers for Disease Control CFE Combined Filter Effluent CFR Code of Federal Regulations COI Cost of Illness CPE Comprehensive Performance Evaluation CT The Residual Concentration of Disinfectant (mg/L) Multiplied by the Contact Time (in minutes) CTA Comprehensive Technical Assistance CWSS Community Water System Survey DBPs Disinfection Byproducts DBPR Disinfectants/Disinfection Byproducts Rule ESWTR Enhanced Surface Water Treatment Rule FACA Federal Advisory Committee Act GAC Granular Activated Carbon GAO Government Accounting Office GWUDI Ground Water Under the Direct Influence of Surface Water HAA5 Haloacetic acids (Monochloroacetic, Dichlor

mprehensive Technical Assistance CWSS Community Water System Survey DBPs Disinfection Byproducts DBPR Disinfectants/Disinfection Byproducts Rule ESWTR Enhanced Surface Water Treatment Rule FACA Federal Advisory Committee Act GAC Granular Activated Carbon GAO Government Accounting Office GWUDI Ground Water Under the Direct Influence of Surface Water HAA5 Haloacetic acids (Monochloroacetic, Dichloroacetic, Trichloroacetic, Monobromoacetic and Dibromoacetic Acids) HPC Heterotropic Plate Count hrs Hours ICR Information Collection Rule IESWTR Interim Enhanced Surface Water Treatment Rule IFA Immunofluorescence Assay Log Inactivation Logarithm of (N o /N T ) Log Logarithm (common, base 10) LTESWTR Long Term Enhanced Surface Water Treatment Rule LT1FBR Long Term 1 Enhanced Surface Water Treatment and Filter Backwash Rule MCL Maximum Contaminant Level MCLG Maximum Contaminant Level Goal MGD Million Gallons per Day M-DBP Microbial and Disinfectants/Disinfection Byproducts MPA Microscopic Particulate Analysis NODA Notice of Data Availability NPDWR National Primary Drinking Water Regulation N T The Concentration of Surviving Microorganisms at Time T NTTAA National Technology Transfer and Advancement Act NTU Nephelometric Turbidity Unit PE Performance Evaluation PWS Public Water System Reg. Neg. Regulatory Negotiation RIA Regulatory Impact Analysis RFA Regulatory Flexibility Act RSD Relative Standard Deviation SAB Science Advisory Board SDWA Safe Drinking Water Act SWTR Surface Water Treatment Rule TC Total Coliforms TCR Total Coliform Rule TTHM Total Trihalomethanes TWG Technical Work Group TWS Transient Non-Community Water System UMRA Unfunded Mandates Reform Act URCIS Unregulated Contaminant Information System x log removal Reduction to 1/10 x of original concentration Table of Contents

I. Introduction and Background

A. Statutory Requirements and Legal Authority B. Existing Regulations and Stakeholder Involvement 1. 1979 Total Trihalomethane Rule 2. Total Coliform Rule 3. Surface Water Treatment Rule 4

ty Water System UMRA Unfunded Mandates Reform Act URCIS Unregulated Contaminant Information System x log removal Reduction to 1/10 x of original concentration Table of Contents

I. Introduction and Background

A. Statutory Requirements and Legal Authority B. Existing Regulations and Stakeholder Involvement 1. 1979 Total Trihalomethane Rule 2. Total Coliform Rule 3. Surface Water Treatment Rule 4. Information Collection Rule 5. Interim Enhanced Surface Water Treatment Rule 6. Stage 1 Disinfectants and Disinfection Byproduct Rule 7. Stakeholder Involvement II. Public Health Risk

A. Introduction B. Health Effects of Cryptosporidiosis and Sources and Transmission of Cryptosporidium C. Waterborne Disease Outbreaks In the United States D. Source Water Occurrence Studies E. Filter Backwash and Other Process Streams: Occurrence and Impact Studies F. Summary and Conclusions III. Baseline Information-Systems Potentially Affected By Today's Proposed Rule

IV. Discussion of Proposed LT1FBR Requirements

A. Enhanced Filtration Requirements 1. Two Log Cryptosporidium Removal Requirement a. Two Log Removal i. Overview and Purpose ii. Data iii. Proposed Requirements iv. Request for Comments 2. Turbidity Requirements a. Combined Filter Effluent i. Overview and Purpose ii. Data iii. Proposed Requirements iv. Request for Comments b. Individual Filter Turbidity i. Overview and Purpose ii. Data iii. Proposed Requirements iv. Request for Comments B. Disinfection Benchmarking Requirements 1. Applicability Monitoring a. Overview and Purpose b. Data c. Proposed Requirements d. Request for Comment 2. Disinfection Profiling a. Overview and Purpose b. Data c. Proposed Requirements d. Request for Comments 3. Disinfection Benchmarking a. Overview and Purpose b. Data c. Proposed Requirements d. Request for Comments C. Additional Requirements

1. Inclusion of Cryptosporidium In Definition of GWUDI a. Overview and Purpose b. Data c. Proposed Requirements d. Request for Comments 2

uest for Comment 2. Disinfection Profiling a. Overview and Purpose b. Data c. Proposed Requirements d. Request for Comments 3. Disinfection Benchmarking a. Overview and Purpose b. Data c. Proposed Requirements d. Request for Comments C. Additional Requirements

1. Inclusion of Cryptosporidium In Definition of GWUDI a. Overview and Purpose b. Data c. Proposed Requirements d. Request for Comments 2. Inclusion of Cryptosporidium Watershed Requirements for Unfiltered Systems a. Overview and Purpose b. Data c. Proposed Requirements d. Request for Comments 3. Requirements for Covering New Reservoirs a. Overview and Purpose b. Data c. Proposed Requirements d. Request for Comments D. Recycle Provisions for Public Water Systems Employing Rapid Granular Filtration Using Surface Water and GWUDI as a Source 1. Treatment Processes that Commonly Recycle and Recycle Flow Occurrence Data a. Treatment Processes that Commonly Recycle i. Conventional Treatment Plants ii. Direct Filtration Plants iii. Softening Plants iv. Contact Clarification Plants v. Package Plants vi. Summary of Recycle Disposal Options b. Recycle Flow Occurrence Data i. Untreated Spent Filter Backwash Water ii. Gravity Settled Spent Filter Backwash Water iii. Combined Gravity Thickener Supernatant iv. Gravity Thickener Supernatant from Sedimentation Solids v. Mechanical Dewatering Device Liquids 2. National Recycle Practices a. Information Collection Rule i. Recycle Practice b. Recycle FAX Survey i. Recycle practice ii. Options to recycle iii. Conclusions 3. Recycle Provisions for PWSs Employing Rapid Granular Filtration Using Surface Water or Ground Water Under the Direct Influence of Surface Water Influence of Surface Water a. Return Select Recycle Streams Prior to the Point of Primary Coagulant Addition i. Overview and Purpose ii. Data iii. Proposed Requirements iv. Request for Comments b. Recycle Requirements for Systems Practicing Direct Recycle and Meeting Specific Criteria i. Overview and Purpose ii. Data iii. Proposed Requirements iv

d Water Under the Direct Influence of Surface Water Influence of Surface Water a. Return Select Recycle Streams Prior to the Point of Primary Coagulant Addition i. Overview and Purpose ii. Data iii. Proposed Requirements iv. Request for Comments b. Recycle Requirements for Systems Practicing Direct Recycle and Meeting Specific Criteria i. Overview and Purpose ii. Data iii. Proposed Requirements iv. Request for Comments c. Requirements for Direct Filtration Plants that Recycle Using Surface Water or GWUDI i. Overview and Purpose ii. Data iii. Proposed Requirements iv. Request for Comments d. Request for Additional Comment V. State Implementation and Compliance Schedules

A. Special State Primacy Requirements B. State Recordkeeping Requirements C. State Reporting Requirements D. Interim Primacy E. Compliance Deadlines VI. Economic Analysis

A. Overview B. Quantifiable and Non-Quantifiable Costs 1. Total Annual Costs 2. Annual Costs of Rule Provisions 3. Non Quantifiable Costs C. Quantifiable and Non-Quantifiable Health Benefits 1. Quantified Health Benefits 2. Non-Quantified Health and Non-Health Related Benefits a. Recycle Provisions b. Issues Associated with Unquantified Benefits D. Incremental Costs and Benefits E. Impacts on Households F. Benefits From the Reduction of Co-Occurring Contaminants G. Risk Increases From Other Contaminants H. Other Factors: Uncertainty in Risk, Benefits, and Cost Estimates I. Benefit Cost Determination J. Request for Comment VII. Other Requirements

A. Regulatory Flexibility Act 1. Today's Proposed Rule 2. Use of Alternative Definition 3. Background and Analysis a. Number of Small Entities Affected b. Recordkeeping and Reporting c. Interaction with Other Federal Rules d. Significant Alternatives i. Turbidity Provisions ii. Disinfection Benchmarking Applicability Monitoring Provisions iii. Recycling Provisions e. Other Comments B. Paperwork Reduction Act C. Unfunded Mandates Reform Act 1. Summary of UMRA requirements 2

Definition 3. Background and Analysis a. Number of Small Entities Affected b. Recordkeeping and Reporting c. Interaction with Other Federal Rules d. Significant Alternatives i. Turbidity Provisions ii. Disinfection Benchmarking Applicability Monitoring Provisions iii. Recycling Provisions e. Other Comments B. Paperwork Reduction Act C. Unfunded Mandates Reform Act 1. Summary of UMRA requirements 2. Written Statement for Rules With Federal Mandates of $100 Million or More a. Authorizing Legislation b. Cost Benefit Analysis c. Estimates of Future Compliance Costs and Disproportionate Budgetary Effects d. Macro-economic Effects e. Summary of EPA's Consultation with State, Local, and Tribal Governments and Their Concerns f. Regulatory Alternatives Considered g. Selection of the Least Costly, Most-Cost Effective or Least Burdensome Alternative That Achieves the Objectives of the Rule 3. Impacts on Small Governments D. National Technology Transfer and Advancement Act E. Executive Order 12866: Regulatory Planning and Review F. Executive Order 12898: Environmental Justice G. Executive Order 13045: Protection of Children from Environmental Health Risks and Safety Risks H. Consultations with the Science Advisory Board, National Drinking Water Advisory Council, and the Secretary of Health and Human Services I. Executive Order 13132: Executive Orders on Federalism J. Executive Order 13084: Consultation and Coordination With Indian Tribal Governments K. Likely Effect of Compliance with the LT1FBR on the Technical, Financial, and Managerial Capacity of Public Water Systems L. Plain Language VIII. Public Comment Procedures

A. Deadlines for Comment B. Where to Send Comment C. Guidelines for Commenting IX. References

I. Introduction and Background

A. Statutory Requirements and Legal Authority

The Safe Drinking Water Act (SDWA or the Act), as amended in 1986, requires U.S

ith the LT1FBR on the Technical, Financial, and Managerial Capacity of Public Water Systems L. Plain Language VIII. Public Comment Procedures

A. Deadlines for Comment B. Where to Send Comment C. Guidelines for Commenting IX. References

I. Introduction and Background

A. Statutory Requirements and Legal Authority

The Safe Drinking Water Act (SDWA or the Act), as amended in 1986, requires U.S. Environmental Protection Agency (EPA) to publish a maximum contaminant level goal (MCLG) for each contaminant which, in the judgement of the EPA Administrator, “may have any adverse effect on the health of persons and which is known or anticipated to occur in public water systems' (Section 1412(b)(3)(A)). MCLGs are to be set at a level at which “no known or anticipated adverse effect on the health of persons occur and which allows an adequate margin of safety” (Section 1412(b)(4)).

The Act was again amended in August 1996, resulting in the renumbering and augmentation of certain sections with additional statutory language. New sections were added establishing new drinking water requirements. These modifications are outlined below.

The Act requires EPA to publish a National Primary Drinking Water Regulation (NPDWR) that specifies

The 1996 amendments, also require EPA, when proposing a NPDWR that includes an MCL or treatment technique, to publish and seek public comment on an analysis of health risk reduction and cost impacts. EPA is required to take into consideration the effects of contaminants upon sensitive subpopulations (i.e., infants, children, pregnant women, the elderly, and individuals with a history of serious illness), and other relevant factors (Section 1412(b)(3)(C)).

ndividuals with a history of serious illness), and other relevant factors (Section 1412(b)(3)(C)).

The amendments established a number of regulatory deadlines, including schedules for a Stage 1 Disinfection Byproduct Rule (DBPR), an Interim Enhanced Surface Water Treatment Rule (IESWTR), a Long Term Final Enhanced Surface Water Treatment Rule (LTESWTR), and a Stage 2 DBPR (Section 1412(b)(2)(C)). To provide additional time for systems serving fewer than 10,000 people to comply with the IESWTR provisions and also ensure these systems implement Stage 1 DBPR and the IESWTR provisions simultaneously, the Agency split the IESWTR into two rules: the IESWR and the LT1ESWTR. The Act as amended also requires EPA to promulgate regulations to “govern” the recycle of filter backwash within the treatment process of public utilities (Section 1412(b)(14)).

Under 1412(b)(4)(E)(ii), EPA must develop a Small System Technology List for the LT1FBR. The filtration technologies listed in the Small System Compliance Technology List for the Surface Water Treatment Rule and Total Coliform Rule (EPA-815-R-98-001, September 1998) are also the technologies which would achieve compliance with the provisions of the LT1FBR. EPA will develop a separate list for the LT1FBR as new technologies become available.

Although the Act permits small system variances for compliance with a requirement of a national primary drinking water regulation which specifies a maximum contaminant level or treatment technique, Section 1415(e)(6)(B) of SDWA, excludes variances for any national primary drinking water regulation for a microbial contaminant or an indicator or treatment technique for a microbial contaminant. LT1FBR requires treatment techniques to control Cryptosporidium (a microbial contaminant), and as such systems governed by the LT1FBR are ineligible for variances

ontaminant level or treatment technique, Section 1415(e)(6)(B) of SDWA, excludes variances for any national primary drinking water regulation for a microbial contaminant or an indicator or treatment technique for a microbial contaminant. LT1FBR requires treatment techniques to control Cryptosporidium (a microbial contaminant), and as such systems governed by the LT1FBR are ineligible for variances.

Finally, as part of the 1996 SDWA Amendments, recordkeeping requirements were modified to apply to every person who is subject to a requirement of this title or who is a grantee (Section 1445(a)(1)(A)). Such persons are required to establish and maintain such records, make such reports, conduct such monitoring, and provide such information as the Administrator may reasonably require by regulation.

B. Existing Regulations and Stakeholder Involvement

1. 1979 Total Trihalomethane Rule

In November 1979 (44 FR 68624) (EPA, 1979) EPA set an interim MCL for total trihalomethanes (TTHM—the sum of chloroform, bromoform, bromodichloromethane, dibromochloromethane) of 0.10 mg/l as an annual average. Compliance is defined on the basis of a running annual average of quarterly averages for four samples taken in the distribution system. The value for each sample is the sum of the measured concentrations of chloroform, bromodichloromethane, dibromochloromethane and bromoform.

The interim TTHM standard applies to community water systems using surface water and/or ground water serving at least 10,000 people that add a disinfectant to the drinking water during any part of the treatment process. At their discretion, States may extend coverage to smaller PWSs; however, most States have not exercised this option. The Stage 1 DBPR (as discussed later) contains updated TTHM requirements.

2. Total Coliform Rule

may extend coverage to smaller PWSs; however, most States have not exercised this option. The Stage 1 DBPR (as discussed later) contains updated TTHM requirements.

2. Total Coliform Rule

The Total Coliform Rule (TCR) (54 FR 27544, June 29, 1989) (EPA, 1989a) applies to all public water systems. The TCR sets compliance with the Maximum Contaminant Level (MCL) for total coliforms (TC) as follows. For systems that collect 40 or more samples per month, no more than 5 percent of the samples may be TC-positive; for those that collect fewer than 40 samples, no more than one sample may be TC-positive. If a system has a TC-positive sample, it must test that sample for the presence of fecal coliforms or E. coli . The system must also collect a set of repeat samples, and analyze for TC (and fecal coliform or E. coli within 24 hours of the first TC-positive sample).

In addition, any fecal coliform-positive repeat sample, E-coli. -positive repeat sample, or any total-coliform-positive repeat sample following a fecal coliform-positive or E-coli -positive routine sample constitutes an acute violation of the MCL for total coliforms. If a system exceeds the MCL, it must notify the public using mandatory language developed by the EPA. The required monitoring frequency for a system depends on the number of people served and ranges from 480 samples per month for the largest systems to once annually for the smallest systems. All systems must have a written plan identifying where samples are to be collected.

The TCR also requires an on-site inspection (referred to as a sanitary survey) every 5 years for each system that collects fewer than five samples per month. This requirement is extended to every 10 years for non-community systems using only protected and disinfected ground water.

ly for the smallest systems. All systems must have a written plan identifying where samples are to be collected.

3. Surface Water Treatment Rule

Under the Surface Water Treatment Rule (SWTR) (54 FR 27486, June 29, 1989) (EPA, 1989b), EPA set maximum contaminant level goals of zero for Giardia lamblia , viruses, and Legionella and promulgated regulatory requirements for all PWSs using surface water sources or ground water sources under the direct influence of surface water. The SWTR includes treatment technique requirements for filtered and unfiltered systems that are intended to protect against the adverse health effects of exposure to Giardia lamblia, viruses, and Legionella, as well as many other pathogenic organisms. Briefly, those requirements include (1) Requirements for maintenance of a disinfectant residual in the distribution system; (2) removal and/or inactivation of 3 log (99.9 percent) for Giardia and 4 log (99.99 percent) for viruses; (3) combined filter effluent turbidity performance standard of 5 nephelometric turbidity units (NTU) as a maximum and 0.5 NTU

4. Information Collection Rule

The Information Collection Rule (ICR), which was promulgated on May 14, 1996 (61 FR 24354) (EPA, 1996) applied to large public water systems serving populations of 100,000 or more. A more limited set of ICR requirements pertain to ground water systems serving between 50,000 and 100,000 people. About 300 PWSs operating 500 treatment plants were involved with the extensive ICR data collection. Under the ICR, these PWSs monitored for water quality factors affecting disinfection byproduct (DBP) formation and DBPs within the treatment plant and in the distribution system on a monthly basis for 18 months

R requirements pertain to ground water systems serving between 50,000 and 100,000 people. About 300 PWSs operating 500 treatment plants were involved with the extensive ICR data collection. Under the ICR, these PWSs monitored for water quality factors affecting disinfection byproduct (DBP) formation and DBPs within the treatment plant and in the distribution system on a monthly basis for 18 months. In addition, PWSs were required to provide treatment train schematics, operating data and source water occurrence data for bacteria, viruses, and protozoa. Finally, a subset of PWSs performed treatment studies, using either granular activated carbon (GAC) or membrane processes, to evaluate DBP precursor removal and control of DBPs. Monitoring for treatment study applicability began in September 1996. The remaining occurrence monitoring began in July 1997 and concluded in December 1998.

The purpose of the ICR was to collect occurrence and treatment information to help evaluate the need for possible changes to the current microbial requirements and existing microbial treatment practices, and to help evaluate the need for future regulation of disinfectants and disinfection byproducts (DBPs). The ICR will provide EPA with additional information on the national occurrence in drinking water of (1) chemical byproducts that form when disinfectants used for microbial control react with naturally occurring compounds already present in source water; and (2) disease-causing microorganisms, including Cryptosporidium , Giardia , and viruses. Analysis of ICR data is not expected to be completed in the time frame necessary for inclusion in the LT1FBR, however if the data is available and has been quality controlled and peer reviewed during the necessary time frame, EPA will consider the datat as it refines its analysis for the final rule.

The ICR also required PWSs to provide engineering data on how they currently control for such contaminants

of ICR data is not expected to be completed in the time frame necessary for inclusion in the LT1FBR, however if the data is available and has been quality controlled and peer reviewed during the necessary time frame, EPA will consider the datat as it refines its analysis for the final rule.

The ICR also required PWSs to provide engineering data on how they currently control for such contaminants. The ICR monthly sampling data will also provide information on the quality of the recycle waters via monthly monitoring (for 18 months) of pH, alkalinity, turbidity, temperature, calcium and total hardness, TOC, UV 254 , bromide, ammonia, and disinfectant residual (if disinfectant is used). This data will provide some indication of the treatability of the water, the extent to which contaminant concentration effects may occur, and the potential for contribution to DBP formation. However, sampling to determine the occurrence of pathogens in recycle waters was not performed.

5. Interim Enhanced Surface Water Treatment Rule

Public water systems serving 10,000 or more people that use surface water or ground water under the direct influence of surface water (GWUDI) are required to comply with the IESWTR (63 FR 69477, December 16, 1998) (EPA, 1998a) by December of 2001. The purposes of the IESWTR are to improve control of microbial pathogens, specifically the protozoan Cryptosporidium , and address risk trade-offs between pathogens and disinfection byproducts

ore people that use surface water or ground water under the direct influence of surface water (GWUDI) are required to comply with the IESWTR (63 FR 69477, December 16, 1998) (EPA, 1998a) by December of 2001. The purposes of the IESWTR are to improve control of microbial pathogens, specifically the protozoan Cryptosporidium , and address risk trade-offs between pathogens and disinfection byproducts. Key provisions established by the rule include: a Maximum Contaminant Level Goal (MCLG) of zero for Cryptosporidium ; 2-log (99 percent) Cryptosporidium removal requirements for systems that filter; strengthened combined filter effluent turbidity performance standards of 1.0 NTU as a maximum and 0.3 NTU at the 95th percentile monthly, based on 4-hour monitoring for treatment plants using conventional treatment or direct filtration; requirements for individual filter turbidity monitoring; disinfection benchmark provisions to assess the level of microbial protection provided as facilities take the necessary steps to comply with new disinfection byproduct standards; inclusion of Cryptosporidium in the definition of GWUDI and in the watershed control requirements for unfiltered public water systems; requirements for covers on new finished water reservoirs; and sanitary surveys for all surface water systems regardless of size.

6. Stage 1 Disinfectants and Disinfection Byproduct Rule

The Stage 1 DBPR applies to all PWSs that are community water systems (CWSs) or nontransient noncommunity water systems (NTNCWs) that treat their water with a chemical disinfectant for either primary or residual treatment. In addition, certain requirements for chlorine dioxide apply to transient noncommunity water systems (TNCWSs). The Stage 1 DBPR (EPA, 1998c) was published at the same time as the IESWTR (63 FR 69477, December 16, 1998) (EPA, 1998a). Surface water and GWUDI systems serving at least 10,000 persons are required to comply with the Stage 1 Disinfectants and Disinfection Byproducts Rule by December 2001

In addition, certain requirements for chlorine dioxide apply to transient noncommunity water systems (TNCWSs). The Stage 1 DBPR (EPA, 1998c) was published at the same time as the IESWTR (63 FR 69477, December 16, 1998) (EPA, 1998a). Surface water and GWUDI systems serving at least 10,000 persons are required to comply with the Stage 1 Disinfectants and Disinfection Byproducts Rule by December 2001. Ground water systems and surface water and GWUDI systems serving fewer than 10,000 must comply with the Stage 1 Disinfectants and Disinfection Byproducts Rule by December 2003.

The Stage 1 DBPR finalizes maximum residual disinfectant level goals (MRDLGs) for chlorine, chloramines, and chlorine dioxide; MCLGs for four trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane, and bromoform), two haloacetic acids (dichloroacetic acid and trichloroacetic acid), bromate, and chlorite; and NPDWRs for three disinfectants (chlorine, chloramines, and chlorine dioxide), two groups of organic disinfection byproducts TTHMs and HAA5 and two inorganic disinfection byproducts, chlorite and bromate. The NPDWRs consist of maximum residual disinfectant levels (MRDLs) or maximum contaminant levels (MCLs) or treatment techniques for these disinfectants and their byproducts. The NPDWRs also include monitoring, reporting, and public notification requirements for these compounds. The Stage 1 DBPR includes the best available technologies (BATs) upon which the MRDLs and MCLs are based. EPA believes the implementation of the Stage 1 DBPR will reduce the levels of disinfectants and disinfection byproducts in drinking water supplies. The Agency believes the rule will provide public health protection for an additional 20 million households that were not previously covered by drinking water rules for disinfection byproducts.

ologies (BATs) upon which the MRDLs and MCLs are based. EPA believes the implementation of the Stage 1 DBPR will reduce the levels of disinfectants and disinfection byproducts in drinking water supplies. The Agency believes the rule will provide public health protection for an additional 20 million households that were not previously covered by drinking water rules for disinfection byproducts.

7. Stakeholder Involvement

EPA conducted two stakeholder meetings to solicit feedback and information from the regulated community and other concerned stakeholders on issues relating to

The Agency utilized the feedback received during these two stakeholder meetings in developing today's proposed rule. EPA also mailed a draft version of the preamble for today's proposed rule to the attendees of these meetings. Several of the options which are presented today represent modifications suggested by stakeholders.

II. Public Health Risk

The purpose of this section is to discuss the health risk associated with pathogens, particularly Cryptosporidium , in surface waters and GWUDI. More detailed information about such pathogens and other contaminants of concern may be found in an EPA criteria document for Giardia (EPA 1998d), three EPA criteria documents for viruses (EPA, 1985; 1999a; 1999b), the Cryptosporidium and Giardia Occurrence Assessment for the Interim Enhanced Surface Water Treatment Rule (EPA, 1998b) and the LT1FBR Occurrence and Assessment Document (EPA 1999c). EPA requests comment on today's proposed rule, the information supporting the proposal, and the potential impact of proposed regulatory provisions on public health risk.

nts for viruses (EPA, 1985; 1999a; 1999b), the Cryptosporidium and Giardia Occurrence Assessment for the Interim Enhanced Surface Water Treatment Rule (EPA, 1998b) and the LT1FBR Occurrence and Assessment Document (EPA 1999c). EPA requests comment on today's proposed rule, the information supporting the proposal, and the potential impact of proposed regulatory provisions on public health risk.

A. Introduction

In 1990, EPA's Science Advisory Board (SAB), an independent panel of experts established by Congress, cited drinking water contamination as one of the most important environmental risks and indicated that disease-causing microbial contaminants (i.e., bacteria, protozoa and viruses) are probably the greatest remaining health risk management challenge for drinking water suppliers (EPA/SAB, 1990). Information on the number of waterborne disease outbreaks from the U.S. Centers for Disease Control and Prevention (CDC) underscores this concern. CDC indicates that, between 1980 and 1996, 401 waterborne disease outbreaks were reported, with over 750,000 associated cases of disease. During this period, a number of agents were implicated as the cause, including protozoa, viruses and bacteria.

Waterborne disease caused by Cryptosporidium is of particular concern, as it is difficult to inactivate Cryptosporidium oocysts with standard disinfection practices (unlike pathogens such as viruses and bacteria), and there is currently no therapeutic treatment for cryptosporidiosis (unlike giardiasis). Because Cryptosporidium is not generally inactivated in systems using standard disinfection practices, the control of Cryptosporidium is dependent on physical removal processes (e.g., filtration).

The filter effluent turbidity limits specified under the SWTR were created to remove large parasite cysts such as Giardia and did not specifically control for smaller Cryptosporidium oocysts

ardiasis). Because Cryptosporidium is not generally inactivated in systems using standard disinfection practices, the control of Cryptosporidium is dependent on physical removal processes (e.g., filtration).

The filter effluent turbidity limits specified under the SWTR were created to remove large parasite cysts such as Giardia and did not specifically control for smaller Cryptosporidium oocysts. In addition, filter backwash water recycling practices such as adding recycled water to the treatment train after primary coagulant addition may overwhelm the plant and harm efforts to control Giardia lamblia, Cryptosporidium , and emerging pathogens. Despite filtration and disinfection, Cryptosporidium oocysts have been found in filtered drinking water (LeChevallier, et al., 1991a; EPA, 1999c), and many of the individuals affected by waterborne disease outbreaks caused by Cryptosporidium were served by filtered surface water supplies (Solo-Gabriele and Neumeister, 1996). Surface water systems that filter and disinfect may still be vulnerable to Cryptosporidium , depending on the source water quality and treatment effectiveness. EPA believes that today's proposal, however, will ensure that drinking water treatment is operating efficiently to control Cryptosporidium (see Sections IV.A and IV.D) and other microbiological contaminants of concern ( e.g., Giardia ).

In order to assess the public health risk associated with consumption of surface water or GWUDI from PWSs, EPA has evaluated information and conducted analysis in four important areas discussed in the following paragraphs. These areas are: (1) The health effects of cryptosporidiosis; (2) cryptosporidiosis waterborne disease outbreak data; (3) Cryptosporidium occurrence data from raw surface water, raw GWUDI, finished water, and recycle stream studies; and (4) an assessment of the current baseline surface water treatment required by existing regulations.

four important areas discussed in the following paragraphs. These areas are: (1) The health effects of cryptosporidiosis; (2) cryptosporidiosis waterborne disease outbreak data; (3) Cryptosporidium occurrence data from raw surface water, raw GWUDI, finished water, and recycle stream studies; and (4) an assessment of the current baseline surface water treatment required by existing regulations.

B. Health Effects of Cryptosporidiosis and Sources and Transmission of Cryptosporidium

Waterborne diseases are usually acute ( i.e., sudden onset and typically lasting a short time in healthy people), and most waterborne pathogens cause gastrointestinal illness, with diarrhea, abdominal discomfort, nausea, vomiting, and/or other symptoms. Some waterborne pathogens cause or are associated with more serious disorders such as hepatitis, gastric cancer, peptic ulcers, myocarditis, swollen lymph glands, meningitis, encephalitis, and many other diseases. Cryptosporidiosis is a protozoal infection that usually causes 7-14 days of diarrhea with possibly a low-grade fever, nausea, and abdominal cramps in healthy individuals (Juranek, 1995). Unlike giardiasis for which effective antibiotic therapy is available, an antibiotic treatment for cryptosporidiosis does not exist (Framm and Soave, 1997).

There are several species of Cryptosporidium which have been identified, including C. baileyi and C. meleagridis (bird host); C. muris (mouse host); C. nasorum (fish host), C. parvum (mammalian host), and C. serpentis (snake host). Cryptosporidium parvum was first recognized as a human pathogen in 1976 (Juranek, 1995). Recently, both the human and cattle types of C. parvum have been found in healthy individuals, and these types, C. felis , and a dog type have been found in immunocompromised individuals (Pieniazek et al., 1999)

is (mouse host); C. nasorum (fish host), C. parvum (mammalian host), and C. serpentis (snake host). Cryptosporidium parvum was first recognized as a human pathogen in 1976 (Juranek, 1995). Recently, both the human and cattle types of C. parvum have been found in healthy individuals, and these types, C. felis , and a dog type have been found in immunocompromised individuals (Pieniazek et al., 1999). Transmission of cryptosporidiosis often occurs through the ingestion of infective Cryptosporidium oocysts from feces-contaminated food or water, but may also result from direct or indirect contact with infected persons or mammals (Casemore, 1990; Cordell and Addiss, 1994). Dupont, et. al., 1995, found through a human feeding study that a low dose of C. parvum is C. parvum has been implicated as the source of contamination for the 1993 outbreak in Milwaukee, Wisconsin, the largest outbreak of waterborne disease in the history of the United States (Walker et al., 1998). Other sources of C. parvum include discharges from municipal wastewater treatment facilities and drainage from slaughterhouses. In addition, rainfall appears to increase the concentration of Cryptosporidium in surface water, documented in a study by Atherholt, et al. (1998).

There is evidence that an immune response to Cryptosporidium exists, but the degree and duration of this immunity is not well characterized (Fayer and Ungar, 1986). Recent work conducted by Chappell, et al. (1999) indicates that individuals with evidence of prior exposure to Cryptosporidium parvum have demonstrated immunity to low doses of oocysts (approximately 500 oocysts). The investigators found the 50 percent infectious dose for previously exposed individuals (possessing a pre-existing blood serum antibody) to be 1,880 oocysts compared to 132 oocysts for individuals without prior exposure, and individuals with prior exposure who became infected shed fewer oocysts

Cryptosporidium parvum have demonstrated immunity to low doses of oocysts (approximately 500 oocysts). The investigators found the 50 percent infectious dose for previously exposed individuals (possessing a pre-existing blood serum antibody) to be 1,880 oocysts compared to 132 oocysts for individuals without prior exposure, and individuals with prior exposure who became infected shed fewer oocysts. Because of this type of immune response, symptomatic infection in communities exposed to chronic low levels of oocysts will primarily be observed in newcomers ( e.g., visitors, young children) (Frost et al ., 1997; Okhuysen et al. , 1998).

Sensitive populations are more likely to become infected and ill, and gastrointestinal illness among this population may be chronic. These sensitive populations include children, especially the very young; the elderly; pregnant women; and the immunocompromised (Gerba et al ., 1996; Fayer and Ungar, 1986; EPA 1998e). This sensitive segment represents almost 20 percent of the population in the U.S. (Gerba et al ., 1996). EPA is particularly concerned about the exposure of severely immunocompromised persons to Cryptosporidium in drinking water, because the severity and duration of illness is often greater in immunocompromised persons than in healthy individuals, and it may be fatal among this population. For instance, a follow-up study of the 1993 Milwaukee, Wisconsin, waterborne disease outbreak reported that at least 50 Cryptosporidium -associated deaths occurred among the severely immunocompromised (Hoxie et al ., 1997).

at least 50 Cryptosporidium -associated deaths occurred among the severely immunocompromised (Hoxie et al ., 1997).

Cases of illness from cryptosporidiosis were rarely reported until 1982, when the disease became prevalent due to the AIDS epidemic (Current, 1983). As laboratory diagnostic techniques improved during subsequent years, outbreaks among immunocompetent persons were recognized as well. Over the last several years there have been a number of documented waterborne cryptosporidiosis outbreaks in the U.S., United Kingdom, Canada and other countries (Rose, 1997, Craun et al ., 1998).

C. Waterborne Disease Outbreaks in the United States

The occurrence of outbreaks of waterborne gastrointestinal infections, including cryptosporidiosis, may be much greater than suggested by reported surveillance data (Craun and Calderon 1996). The CDC-EPA, and the Council of State and Territorial Epidemiologists have maintained a collaborative surveillance program for collection and periodic reporting of data on waterborne disease outbreaks since 1971. The CDC database and biennial CDC-EPA surveillance summaries include data reported voluntarily by the States on the incidence and prevalence of waterborne illnesses. However, the following information demonstrates why the reported surveillance data may under-report actual outbreaks.

The U.S. National Research Council strongly suggests that the number of identified and reported outbreaks in the CDC database (both for surface and ground waters) represents a small percentage of actual waterborne disease outbreaks National Research Council, 1997; Bennett et al ., 1987). In practice, most waterborne outbreaks in community water systems are not recognized until a sizable proportion of the population is ill (Perz et al .)

Healthy adults with cryptosporidiosis may not suffer severe symptoms from the disease; therefore, infected individuals may not seek medical assistance, and their cases are subsequently not reported

Research Council, 1997; Bennett et al ., 1987). In practice, most waterborne outbreaks in community water systems are not recognized until a sizable proportion of the population is ill (Perz et al .)

Healthy adults with cryptosporidiosis may not suffer severe symptoms from the disease; therefore, infected individuals may not seek medical assistance, and their cases are subsequently not reported. Even if infected individuals consult a physician, Cryptosporidium may not be identified by routine diagnostic tests for gastroenteritis and, therefore, tends to be under-reported in the general population (Juranek 1995). Such obstacles to outbreak reporting indicate that the incidence of disease and outbreaks of cryptosporidiosis may be much higher than officially reported by the CDC.

The CDC database is based upon responses to a voluntary and confidential survey that is completed by State and local public health officials. CDC defines a waterborne disease outbreak as occurring when at least two persons experience a similar illness after ingesting water (Kramer et al. , 1996). Cryptosporidiosis water system outbreak data from the CDC database appear in Table II.1 and Table II.2.

Table II.1 illustrates the reported number of waterborne disease outbreaks in U.S. community, noncommunity, and individual drinking water systems between 1971 and 1996. According to the CDC-EPA database, a total of 652 outbreaks and 572,829 cases of illnesses were reported between 1971 and 1996 (see Table II-1). The total number of outbreaks reported includes outbreaks resulting from protozoan contamination, virus contamination, bacterial contamination, chemical contamination, and unknown factors

unity, and individual drinking water systems between 1971 and 1996. According to the CDC-EPA database, a total of 652 outbreaks and 572,829 cases of illnesses were reported between 1971 and 1996 (see Table II-1). The total number of outbreaks reported includes outbreaks resulting from protozoan contamination, virus contamination, bacterial contamination, chemical contamination, and unknown factors.

Table II.1.—Comparison of Outbreaks and Outbreak-Related Illnesses From Ground Water and Surface Water for the Period 1971-1996 1 Water source Total outbreaks 2 Cases of 2 illnesses Outbreaks in CWSs Outbreaks in NCWSs Ground 371 (57%) 90,815 (16%) 113 258 Surface 223 (34%) 471,375 (82%) 148 43 Other 58 (9%) 10,639 (2%) 30 19 All Systems 3 652 (100%) 572,829 (100%) 291 320 1 Craun and Calderon, 1994, CDC, 1998. 2 Includes outbreaks in CWSs + NCWSs + Private wells. Epidemiological investigations of outbreaks in populations served by filtered systems have shown that treatment deficiencies have resulted in the plants' failure to remove contamination from the water. Sometimes operational deficiencies have been discovered only during post-outbreak investigations. Rose (1997) identified the following types of environmental and operating conditions commonly present in filtered surface water systems at the time cryptosporidiosis outbreaks have occurred:

• Improperly-installed, -operated, -maintained, or -interpreted monitoring

• Equipment ( e.g. , turbidimeters);

• Inoperable flocculators, chemical injectors, or filters;

• Inadequate personnel response to failures of primary monitoring equipment;

• Filter backwash recycle;

• High concentrations of oocysts in source water with no mitigative barrier;

• Flushing of oocysts (by heavy rain or snow melt) from land surfaces upstream of the plant intakes; and

• Altered or suboptimal filtration during periods of high turbidity, with turbidity spikes detected in finished water.

From 1984 to 1994, there have been 19 reported outbreaks of cryptosporidiosis in the U.S

• High concentrations of oocysts in source water with no mitigative barrier;

• Flushing of oocysts (by heavy rain or snow melt) from land surfaces upstream of the plant intakes; and

• Altered or suboptimal filtration during periods of high turbidity, with turbidity spikes detected in finished water.

From 1984 to 1994, there have been 19 reported outbreaks of cryptosporidiosis in the U.S. (Craun et al., 1998). As mentioned previously, C. parvum was not identified as a human pathogen until 1976. Furthermore, cryptosporidiosis outbreaks were not reported in the U.S. prior to 1984. Ten of these cryptosporidiosis outbreaks have been documented in CWSs, NCWSs, and a private water system (Moore et al. , 1993; Kramer et al., 1996; Levy et al. , 1998; ; Craun et al. , 1998). The remaining nine outbreaks were associated with recreational activities (Craun et al. , 1998). The cryptosporidiosis outbreaks in U.S. drinking water systems are presented in Table II.2.

Table II.2.—Cryptosporidiosis Outbreaks in U.S. Drinking Water Systems Year Location and CWS, NCWS, or private Cases of illness (estimated) Source water Treatment Suspected cause 1984 Braun Station, TX, CWS 117 (2,000) Well Chlorination Sewage-contaminated well. 1987 Carrollton, GA, CWS (13,000) River Conventional filtration/chlorination; inadequate backwashing of some filters Treatment deficiencies. 1991 Berks County, PA, NCWS (551) Well Chlorination Ground water under the influence of surface water. 1992 Medford (Jackson County), OR, CWS (3,000; combined total for Jackson County and Talent, below) Spring/River Chlorination/package filtration plant Source not identified. 1992 Talent, OR, CWS see Medford, OR Spring/River Chlorination/package filtration plant Treatment deficiencies. 1993 Milwaukee, WI, CWS (403,000) Lake Conventional filtration High source water contamination and treatment deficiencies. 1993 Yakima, WA, private 7 Well N/A Ground water under the influence of surface water

elow) Spring/River Chlorination/package filtration plant Source not identified. 1992 Talent, OR, CWS see Medford, OR Spring/River Chlorination/package filtration plant Treatment deficiencies. 1993 Milwaukee, WI, CWS (403,000) Lake Conventional filtration High source water contamination and treatment deficiencies. 1993 Yakima, WA, private 7 Well N/A Ground water under the influence of surface water. 1993 Cook County, MN, NCWS 27 Lake Filtered, chlorinated Possible sewage backflow from toilet/septic tank. 1994 Clark County, NV, CWS 103; many confirmed for cryptosporidiosis were HIV positive River/Lake Prechlorination, filtration and post-filtration chlorination Source not identified. 1994 Walla Walla, WA, CWS 134 Well None reported Sewage contamination. Craun, et al., 1998. Six of the ten cryptosporidiosis outbreaks reported in Table II.2 originated from surface water or possibly GWUDI supplied by public drinking water systems serving fewer than 10,000 persons. The first outbreak (117 known cases, 2,000 estimated cases of illness), in Braun Station, Texas in 1984, was caused by sewage leaking into a ground water well suspected to be under the influence of surface water. A second outbreak in Pennsylvania in 1991 (551 estimated cases of illness), occurred at a well also under the influence of surface water. The third and fourth (multi-episodic) outbreaks took place in Jackson County, Oregon in 1992 (3,000 estimated cases of illness) and were linked to treatment deficiencies in the Talent, OR surface water system. A fifth outbreak (27 cases of illness) in Minnesota, in 1993, occurred at a resort supplied by lake water. Finally, a sixth outbreak (134 cases of illness) in Washington in 1994, occurred due to sewage-contaminated wells at a CWS.

red at a resort supplied by lake water. Finally, a sixth outbreak (134 cases of illness) in Washington in 1994, occurred due to sewage-contaminated wells at a CWS.

Three of the ten outbreaks (Carollton, GA (1987); Talent, OR (1992); Milwaukee, WI (1993)) were caused by water supplied by water treatment plants where the recycle of filter backwash was implicated as a possible cause of the outbreak. In total, the nine outbreaks which have taken place in PWSs have caused an estimated 419,939 cases of illness. These outbreaks illustrate that when treatment in place is not operating optimally or when source water is highly contaminated, Cryptosporidium may enter the finished drinking water and infect drinking water consumers, ultimately resulting in waterborne disease outbreaks.

D. Source Water Occurrence Studies

Cryptosporidium is common in the environment (Rose, 1988; LeChevallier et al., 1991b). Runoff from unprotected watersheds allows the transport of these microorganisms from sources of oocysts ( e.g., untreated wastewater, agricultural runoff) to water bodies used as intake sites for drinking water treatment plants. If treatment operates inefficiently, oocysts may enter the finished water at levels of public health concern. A particular public health challenge is that simply increasing existing disinfection levels above those most commonly practiced for standard disinfectants (i.e., chlorine or chloramines) in the U.S. today does not appear to be an effective strategy for controlling Cryptosporidium .

chloramines) in the U.S. today does not appear to be an effective strategy for controlling Cryptosporidium .

Cryptosporidium oocysts have been detected in wastewater, pristine surface water, surface water receiving agricultural runoff or contaminated by sewage, ground water under the direct influence of surface water (GWUDI), water for recreational use, and drinking water (Rose 1997, Soave 1995). Over 25 environmental surveys have reported Cryptosporidium source water occurrence data from surface water or GWUDI (presented in Tables II.3 and II.4), which typically involved the collection of a few water samples from a number of sampling locations having different characteristics (e.g., polluted vs. pristine; lakes or reservoirs vs. rivers). Results are presented as oocysts per 100 liters, unless otherwise marked.

Each of the studies cited in Tables II.3 and II.4 presents Cryptosporidium source water occurrence information, including (where possible): (1) The number of samples collected; (2) the number of samples positive; and (3) both the means and ranges for the concentrations of Cryptosporidium detected (where available). However, the immunofluorescence assay (IFA) method and other Cryptosporidium detection methods are inaccurate and lack adequate precision. Current methods do not indicate the species of Cryptosporidium identified or whether the oocysts detected are viable or infectious (Frey et al., 1997). The methods for detecting Cryptosporidium were modeled from Giardia methods, therefore recovery of Cryptosporidium is deficient primarily because Cryptosporidium oocysts are more difficult to capture due to their size ( Cryptosporidium oocysts are 4-6 mu; m; Giardia cysts are 8-12 mu; m). In addition, it is a challenge to recover Cryptosporidium oocysts from the filters when they are concentrated, due to the adhesive character of the organisms

modeled from Giardia methods, therefore recovery of Cryptosporidium is deficient primarily because Cryptosporidium oocysts are more difficult to capture due to their size ( Cryptosporidium oocysts are 4-6 mu; m; Giardia cysts are 8-12 mu; m). In addition, it is a challenge to recover Cryptosporidium oocysts from the filters when they are concentrated, due to the adhesive character of the organisms. Other potential limitations to the protozoan detection methods include: (1) Filters used to concentrate the water samples are easily clogged by debris from the water sample; (2) interference occurs between debris or particulates that fluoresce due to cross reactivity of antibodies, which results in false positive identifications; (3) it is difficult to view the structure of oocysts on the membrane filter or slide, resulting in false negative determinations; and (4) most methods require an advanced level of skill to be performed accurately.

Despite these limitations, the occurrence information generated from these studies demonstrates that Cryptosporidium occurs in source waters. The source waters for which EPA has compiled information include rivers, reservoirs, lakes, streams, raw water intakes, springs, wells under the influence of surface water and infiltration galleries. The most comprehensive study in scope and national representation (LeChevallier and Norton, 1995) will be described in further detail following Tables II.3 and II.4.

Table II.3.—Summary of Surface Water Survey and Monitoring Data for Cryptosporidium Oocysts Sample source Number of samples (n) Samples positive for Cryptosporidium (percent) a Range of oocyst conc. (oocysts/100L) Mean (oocysts/100L) Reference Rivers 25 100 200-11,200 2510 Ongerth and Stibbs 1987. River 6 100 200-580,000 192,000(a) Madore et al. 1987. Reservoirs/rivers (polluted) 6 100 19-300 99(a) Rose 1988. Reservoir (pristine) 6 83 1-13 2(a) Rose 1988. Impacted river 11 100 200-11,200 b 2,500(g) Rose et al. 1988a b . Lake 20 71 0-2200 58(g) Rose et al. 1988b b

ent) a Range of oocyst conc. (oocysts/100L) Mean (oocysts/100L) Reference Rivers 25 100 200-11,200 2510 Ongerth and Stibbs 1987. River 6 100 200-580,000 192,000(a) Madore et al. 1987. Reservoirs/rivers (polluted) 6 100 19-300 99(a) Rose 1988. Reservoir (pristine) 6 83 1-13 2(a) Rose 1988. Impacted river 11 100 200-11,200 b 2,500(g) Rose et al. 1988a b . Lake 20 71 0-2200 58(g) Rose et al. 1988b b . Stream 19 74 0-24,000 109(g) Rose et al. 1988b b Raw water 85 87 7-48,400 270(g) detectable LeChevallier et al. 1991c. River (pristine) 59 32 NR 29(g) Rose et al. 1991. River (polluted) 38 74 <0.1-4,400 b 66(g) Rose et al. 1991. Lake/reservoir (pristine) 34 53 NR 9.3(g) Rose et al. 1991. Lake/reservoir (polluted) 24 58 <0.1-380 b 103(g) Rose et al. 1991. River (all samples) 36 97 15-45 (pristine) 1000-6,350 (agricultural) 20 (pristine) 1,830 (agricultural) Hansen and Ongerth 1991. Protected drinking water supply (subset of all) 6 81 15-42 24(g) Hansen and Ongerth 1991. Pristine river, forestry area (subset of all) 6 100 46-697 162(g) Hansen and Ongerth 1991. River below rural community in forested area (subset of all) 6 100 54-360 107(g) Hansen and Ongerth 1991. River below dairy farming agricultural activities (subset of all) 6 100 330-6,350 1,072(g) Hansen and Ongerth 1991. Reservoirs 56 45 NR NR Consonery et al. 1992. Streams 33 48 NR NR Consonery et al. 1992. Rivers 37 51 NR NR Consonery et al. 1992. Site 1—River source (high turbidity) 10 100 82-7,190 480 LeChevallier and Norton 1992. Site 2—River source (moderate turbidity) 10 70 42-510 250 LeChevallier and Norton 1992. Site 3—Reservoir source (low turbidity) 10 70 77-870 250 LeChevallier and Norton 1992. Lakes 179 6 0-2,240 3.3 (median) Archer et al. 1995. Streams 210 6 0-2,000 7 (median) Archer et al. 1995. Finished water 262 13 0.29-57 33 (detectable) LeChevallier and Norton 1995. River/lake 262 52 6.5-6,510 240 (detectable) LeChevallier and Norton 1995. River/lake 147 20 30-980 200 LeChevallier et al. 1995

2. Site 3—Reservoir source (low turbidity) 10 70 77-870 250 LeChevallier and Norton 1992. Lakes 179 6 0-2,240 3.3 (median) Archer et al. 1995. Streams 210 6 0-2,000 7 (median) Archer et al. 1995. Finished water 262 13 0.29-57 33 (detectable) LeChevallier and Norton 1995. River/lake 262 52 6.5-6,510 240 (detectable) LeChevallier and Norton 1995. River/lake 147 20 30-980 200 LeChevallier et al. 1995. River 1 15 73 0-2,230 188 (a) all samples 43 (g) detected States et al. 1995. River 2 15 80 0-1,470 147 (a) all samples 61 (g) detected States et al. 1995. Dairy farm stream 13 77 0-1,110 126 (a) all samples 55 (g) detected States et al. 1995. Reservoir inlets 60 5 0.7-24 1.9(g) 1.6 (median) LeChevallier et al. 1997b. Reservoir outlets 60 12 1.2-107 6.1(g) 60 (median) LeChevallier et al. 1997b. River (polluted) 72 40 20-280 24(g) LeChevallier et al. 1997a. Source water NR 24 1-5,390 c 740(a) c 71(g) c Swertfeger et al. 1997. First flush (storm event) 20 35 0-41,700 NR Stewart et al. 1997. Grab (non-storm event) 21 19 0-650 NR Stewart et al. 1997. River 1 24 63 0-1,470 58(g) States et al. 1997. Stream by dairy farm 22 82 0-2,300 42(g) States et al. 1997. River 2 (at plant intake) 24 63 0-2,200 31(g) States et al. 1997. Reservoirs (unfiltered system) NR 37-52 d 15-43 (maxima) d 0.8-1.4 d Okun et al. 1997. Raw water intakes 148 25 0.04-18 0.3 Consonery et al. 1997. Raw water intakes (rural) NR NR 40-400 NR Swiger et al. 1999. Raw Water 100 plants 77 0.5-117 3(g) McTigue, et al. 1998. DE River, Winter 18 NR NR 70 per 500L(g) Atherholt, et al. 1998. DE River, Spring 18 NR NR 100 per 500L(g) Atherholt, et al. 1998. DE River, Summer 18 NR NR 30 per 500L(g) Atherholt, et al. 1998. DE River, Fall 18 NR NR 20 per 500L(g) Atherholt, et al. 1998. a Rounded to nearest percent. b As cited in Lisle and Rose 1995. c Based on presumptive oocyst count d Combined monitoring results for multiple sites in large urban water supply. e As cited in States et al. 1997. (a) = arithmetic average. (g) = geometric average

al. 1998. DE River, Summer 18 NR NR 30 per 500L(g) Atherholt, et al. 1998. DE River, Fall 18 NR NR 20 per 500L(g) Atherholt, et al. 1998. a Rounded to nearest percent. b As cited in Lisle and Rose 1995. c Based on presumptive oocyst count d Combined monitoring results for multiple sites in large urban water supply. e As cited in States et al. 1997. (a) = arithmetic average. (g) = geometric average. NR = not reported, NA = not applicable. Table II.4.—Summary of U.S. GWUDI Monitoring Data for Cryptosporidium Oocysts Sample source Number of samples (n) Samples positive for Cryptosporidium oocysts (percent) Range of positive values (oocysts/100L) Mean (oocysts/ 100L) a Reference Well 17 (6 wells) (1 sample) .085L NA Archer et al. 1995. Ground water sources (all categories) 199 sites b 11 b 0.002-0.45d NR Hancock et al. 1998. Vertical wells (subcategory of above ground water sources) 149 sites b 5 b NR NR Hancock et al. 1998. Springs (subcategory of above ground water sources) 35 sites b 20 b NR NR Hancock et al. 1998. Infiltration galleries (subcategory of above ground water sources) 4 sites b 50 b NR NR Hancock et al. 1998. Horizontal wells (subcategory of above ground water sources) 11 sites b 45 b NR NR Hancock et al. 1998. Ground water 17 41.2 NR NR Rosen et al., 1996. Ground water 18 5.6 .13 .13 Rose et al. 1991. Springs 7 (4 springs) 57 b 0.25-10 4 Rose et al. 1991. Wells 5 sites 100 0.26-3 0.9 SAIC, 1997 c Vertical well Lemont Well #4 (Center Co., PA, Aug. 1992) 6 66.7 NR NR Lee, 1993. a Geometric mean reported unless otherwise indicated. b Data are presented as the percentage of positive sites. c Data included are confirmed positive samples not reported in Hancock, 1998. NA = not applicable. NR = not reported. The LeChevallier and Norton (1995) study collected the most samples and repeat samples from the largest number of surface water plants nationally. LeChevallier and Norton conducted the study to determine the level of Cryptosporidium in surface water supplies and plant effluent water

Data included are confirmed positive samples not reported in Hancock, 1998. NA = not applicable. NR = not reported. The LeChevallier and Norton (1995) study collected the most samples and repeat samples from the largest number of surface water plants nationally. LeChevallier and Norton conducted the study to determine the level of Cryptosporidium in surface water supplies and plant effluent water. In total, surface water sources for 72 treatment plants in 15 States and 2 Canadian provinces were sampled. Sixty-seven surface water locations were examined. The generated data set covered a two-year monitoring period (March, 1991 to January, 1993) which was combined with a previous set of data (October, 1988 to June, 1990) collected from most of the same set of systems to create a database containing five samples (IFA) per site or more for 94 percent of the 67 systems sampled. Cryptosporidium oocysts were detected in 135 (51.5 percent) of the 262 raw water samples collected between March 1991 and January 1993, while 87 percent of the 85 samples were positive during the survey period from October, 1988 to June, 1990. The geometric mean of detectable Cryptosporidium was 240 oocysts/100L, with a range from 6.5 to 6510 oocysts/100L. When the 1991-1993 results (n=262) were combined with the previous results (n=85), Cryptosporidium was detected in 60.2 percent of the samples. The authors hypothesize the origin of the decrease in detections in the second round of sampling to be most probably linked to fluctuating or declining source water concentrations of Cryptosporidium oocysts from the first reporting period to the second.

most probably linked to fluctuating or declining source water concentrations of Cryptosporidium oocysts from the first reporting period to the second.

LeChevallier and Norton (1995) also detected Cryptosporidium oocysts in 35 of 262 plant effluent samples (13.4 percent) analyzed between 1991 and 1993. When detected, the oocyst levels averaged 3.3 oocysts/100 L (range = 0.29 to 57 oocysts/100 L). A summary of occurrence data for all samples in filtered effluents for the years 1988 to 1993 showed that 32 of the water treatment plants (45 percent) were consistently negative for Cryptosporidium ; 24 plants (34 percent) were positive once; and 15 plants (21 percent) were positive for Cryptosporidium two or more times between 1988 to 1993. Forty-four of the plants (62 percent) were positive for Giardia , Cryptosporidium , or both at one time or another (LeChevallier and Norton 1995).

The oocyst recoveries and densities reported by LeChevallier and Norton (1995) are comparable to the results of another survey of treated, untreated, protected (pristine) and feces-contaminated (polluted) water supplies (Rose et al. 1991). Six of thirty-six samples (17 percent) taken from potable drinking water were positive for Cryptosporidium , and concentrations in these waters ranged from .5 to 1.7 oocysts/100L. In addition, a total of 188 surface water samples were analyzed from rivers, lakes, or springs in 17 States. The majority of surface water samples were obtained from Arizona, California, and Utah (126 samples in all), with others from eastern States (28 samples), northwestern States (14 samples), southern States (13 samples), midwestern States (6 samples), and Hawaii (1 sample). Arithmetic average oocyst concentrations ranged from less than 1 to 4,400 oocysts/100 L, depending on the type of water analyzed. Cryptosporidium oocysts were found in 55 percent of the surface water samples at an average concentration of 43 oocysts/100 L

stern States (28 samples), northwestern States (14 samples), southern States (13 samples), midwestern States (6 samples), and Hawaii (1 sample). Arithmetic average oocyst concentrations ranged from less than 1 to 4,400 oocysts/100 L, depending on the type of water analyzed. Cryptosporidium oocysts were found in 55 percent of the surface water samples at an average concentration of 43 oocysts/100 L.

The LeChevallier and Norton (1995) study collected the most samples and repeat samples from the most surface water plants on a national level. Therefore, the data from this study were analyzed by EPA (EPA, 1998n) to generate a distribution of source water occurrence, presented in Table II.5.

Table II.5.—Baseline Expected National Source Water Cryptosporidium Distributions Percentile Source water concentration (oocysts/100L) 25 103 50 231 75 516 90 1064 95 1641 Mean 470 Standard Deviation 841 Although limited by the small number of samples per site (one to sixteen samples; most sites were sampled five times), the mean concentration at the 69

In addition to the source water data, several studies have detected Cryptosporidium oocysts in finished water. The results of these studies have been compiled in Table II.6.

Table II.6.—Summary of U.S. Finished Water Monitoring Data for Cryptosporidium Oocysts Sample source Number of samples (n) Samples positive for Cryptosporidium (percent) Range of oocyst conc. (oocysts/100L) Mean (oocysts/100L) Reference Filtered water 82 27 0.1-48 1.5 LeChevallier et al. 1991a. Finished water (unfiltered) 6 33 0.1-1.7 0.2 LeChevallier et al. 1992. Finished water 262 13 0.29-57 33 (detectable) LeChevallier and Norton 1995. Finished water (clearwell) 14 14 NR NR Consonery et al. 1992. Finished water (filter effluents) 118 26 NR NR Consonery et al. 1992. Site 1—Filter effluent 10 70 1-4 NR LeChevallier and Norton 1992. Site 2—Filter effluent 10 10 0.5 NA LeChevallier and Norton 1992. Site 3—Filter effluent 10 10 2 NA LeChevallier and Norton 1992. Finished water 1,237 7 NR NR Rosen et al

) LeChevallier and Norton 1995. Finished water (clearwell) 14 14 NR NR Consonery et al. 1992. Finished water (filter effluents) 118 26 NR NR Consonery et al. 1992. Site 1—Filter effluent 10 70 1-4 NR LeChevallier and Norton 1992. Site 2—Filter effluent 10 10 0.5 NA LeChevallier and Norton 1992. Site 3—Filter effluent 10 10 2 NA LeChevallier and Norton 1992. Finished water 1,237 7 NR NR Rosen et al. 1996. Filtered (non-storm event) 87 10 0-420 NR Stewart et al. 1997a. Finished water 24 **8 ***13 0-0.6 0.5 (g) States et al. 1997. Finished water 155 2.5 0.02-0.8 0.2 Consonery et al. 1997. Finished water 100 15 0.04-0.08 0.08 (g) McTigue, et al. 1998. *Plants **Confirmed ***Presumed These studies show that despite some treatment in place, Cryptosporidium may still pass through the treatment plant and into finished water.

In general, oocysts are detected more frequently and in higher concentrations in rivers and streams than in lakes and reservoirs (LeChevallier et al. , 1991b; Rose et al. , 1988a,b). Madore et al. (1987) found high concentrations of oocysts in a river affected by agricultural runoff (5800 oocysts/L). Such concentrations are especially significant if the contaminant removal process ( e.g. , sedimentation, filtration) of the treatment plant is not operating effectively. Oocysts may pass through to the finished water, as LeChevallier and Norton (1995) and several other researchers also found, and infect drinking water consumers.

E. Filter Backwash and Other Process Streams: Occurrence and Impact Studies

Pathogenic microorganisms are removed during the sedimentation and/or filtration processes in a water treatment plant. Recycle streams generated during treatment, such as spent filter backwash water, sedimentation basin sludge, or thickener supernatant are often returned to the treatment train. These recycle streams, therefore, may contain high concentrations of pathogens, including chlorine-resistant Cryptosporidium oocysts

e removed during the sedimentation and/or filtration processes in a water treatment plant. Recycle streams generated during treatment, such as spent filter backwash water, sedimentation basin sludge, or thickener supernatant are often returned to the treatment train. These recycle streams, therefore, may contain high concentrations of pathogens, including chlorine-resistant Cryptosporidium oocysts. Recycle can degrade the treatment process, especially when entering the treatment train after the rapid mix stage, by causing a chemical imbalance, hydraulic surge and potentially overwhelming the plant's filtration capacity with a large concentration of pathogens. High oocyst concentrations found in recycle waters can increase the risk of pathogens passing through the treatment plant into finished water.

AWWA has compiled issue papers on each of the following recycle streams: Spent filter backwash water, sedimentation basin solids, combined thickener supernatant, ion-exchange regenerate, membrane concentrate, lagoon decant, mechanical dewatering device concentrate, monofill leachate, sludge drying bed leachate, and small-volume streams ( e.g. , floor, roof, lab drains) (Environmental Engineering & Technology, 1999). In addition, EPA compiled existing occurrence data on Cryptosporidium in recycle streams. Through these efforts, Cryptosporidium occurrence data has been found for three types of recycle streams: Spent filter backwash water, sedimentation basin solids, and thickener supernatant.

Nine studies have reported the occurrence of Cryptosporidium for these process streams. Each study's scope and results are presented in Table II.7, and brief narratives on each major study follow the table. Note that the results of the studies, if not presented in the published report as oocysts/100L, have been converted into oocysts/100L

r, sedimentation basin solids, and thickener supernatant.

Table II.7.—Cryptosporidium Occurrence in Filter Backwash and Other Recycle Streams Name/location of study Number of samples (n) Type of sample Cyst/oocyst concentration Number of treatment plants sampled Reference Drinking water treatment facilities 2 backflush waters from rapid sand filters sample 1: 26,000 oocysts/gal (calc. as 686,900 oocysts/100L) 2 Rose et al. 1986. sample 2: 92,000 oocysts/gal (calc as 2,430,600 oocysts/100L) Thames, U.K., not reported backwash water from rapid sand filter Over 1,000,000 oocysts/100L in backwash water on 2/19/89 1 Colbourne 1989. 100,000 oocysts/100L in supernatant from settlement tanks during the next few days Potable water supplies in 17 States not reported filter backwash from rapid sand filters (10 to 40 L sample vol.) 217 oocysts/ 100 L (geometric mean) not reported Rose et al. 1991. Name/location not reported not reported raw water initial backwash water 7 to 108 oocysts/100L detected at levels 57 to 61 times higher than in the raw water not reported not reported LeChevallier et al. 1991c. Bangor Water Treatment Plant (PA) Round 1: 1 (8-hour composite) raw water filter backwash supernatant recycle 6 oocysts/100L 902 oocysts/100L. 141 oocysts/100L. 1 Cornwell and Lee 1993. Round 2: 1 (8-hour composite) raw water filter backwash supernatant recycle 140 oocysts/100L 850 oocysts/100L. 750 oocysts/100L. 1 Cornwell and Lee 1993. Moshannon Valley Water Treatment Plant Round 1: 1 (8-hour composite) raw water spent backwash supernatant recycle sludge 13 oocysts/100L 16,613 oocysts/100L. 82 oocysts/100L. 2,642 oocysts/100L. 1 Cornwell and Lee 1993

L. 1 Cornwell and Lee 1993. Round 2: 1 (8-hour composite) raw water filter backwash supernatant recycle 140 oocysts/100L 850 oocysts/100L. 750 oocysts/100L. 1 Cornwell and Lee 1993. Moshannon Valley Water Treatment Plant Round 1: 1 (8-hour composite) raw water spent backwash supernatant recycle sludge 13 oocysts/100L 16,613 oocysts/100L. 82 oocysts/100L. 2,642 oocysts/100L. 1 Cornwell and Lee 1993. Round 2: 1 (8-hour composite) raw water supernatant recycle 20 oocysts/100L 420 oocysts/100L. 1 Cornwell and Lee 1993. Plant “C” 11 samples using continuous flow centrifugation; 39 samples using cartridge filters backwash water from rapid sand filters; samples collected from sedimentation basins during sedimentation phase of backwash water at depths of 1, 2, 3, and 3.3 m continuous flow: range 1 to 69 oocysts/100 L; 8 of 11 samples positive cartridge filters: ranges 0.8 to 252/100 L; 33 of 39 samples positive 1 Karanis et al. 1996. Pittsburgh Drinking Water Treatment Plant 24 (two years of monthly samples) filter backwash 328 oocysts/ 100 L (geometric mean); (38 percent occurrence rate) non-detect-13,158 oocysts/100L. 1 States et al. 1997. “Plant Number 3” not reported raw water spent backwash 140 oocysts/100L 850 oocysts/100L. not reported Cornwell 1997. “Plant C” (see Karanis, et al., 1996) 12 50 raw water backwash water from rapid sand filters avg. 23.2 oocysts/100L (max. 109 oocysts/100L) in 8 of 12 samples avg. 22.1 oocysts/100L (max. 257 oocysts/100L) in 41 of 50 samples 1 Karanis et al 1998. “Plant A” 1 rapid sand filter (sample taken 10 min. after start of backwashing) 150 oocysts/100L The occurrence data available and reported are primarily for raw and recycle stream water. If filter backwash enters the treatment train as a slug load and disrupts the treatment process, it is possible its effects would not be readily seen in the finished water until several minutes or hours after returning the filter to service

r (sample taken 10 min. after start of backwashing) 150 oocysts/100L The occurrence data available and reported are primarily for raw and recycle stream water. If filter backwash enters the treatment train as a slug load and disrupts the treatment process, it is possible its effects would not be readily seen in the finished water until several minutes or hours after returning the filter to service. In addition, the poor recovery efficiencies of the IFA Cryptosporidium detection method complicate measurements in dilute finished effluent waters.

As shown in Table II.7, the concentrations of oocysts in backwash water and other recycle streams are greater than the concentrations generally found in raw water. For example, four studies (Cornwell and Lee, 1993; States et al., 1997; Rose et al., 1986; and Colbourne, 1989) have reported Cryptosporidium oocyst concentrations in filter backwash water exceeding 10,000 oocysts/100L. Such concentrations illustrate that the treatment plant has been removing oocysts from the influent water during the sedimentation and/or filtration processes. As expected, the oocysts have concentrated on the filters and/or in the sedimentation basin sludge. Therefore, the recycling of such process streams ( e.g., filter backwash, thickener supernatant, sedimentation basin

Recycle can potentially return a significant number of oocysts to the treatment plant in a short amount of time, particularly if the recycle is returned to the treatment process without prior treatment, equalization, or some other type of hydraulic detention. In addition, Di Giovanni, et al. (1999) presented data indicating that viable oocysts have been detected in filter backwash samples using a cell culture/polymerase chain reaction (PCR) method. Cell culture is a test of the viability/infectivity of the oocysts, while PCR identified the cells infected by C. parvum

ess without prior treatment, equalization, or some other type of hydraulic detention. In addition, Di Giovanni, et al. (1999) presented data indicating that viable oocysts have been detected in filter backwash samples using a cell culture/polymerase chain reaction (PCR) method. Cell culture is a test of the viability/infectivity of the oocysts, while PCR identified the cells infected by C. parvum . Although recovery by IFA was poor (6 to 8 percent for backwash samples), 9 filter backwash recycle samples were found to contain viable and infectious oocysts, and the infectious agent was determined to be more than 98 percent similar in structure to C. parvum . Should filter backwash recycle disrupt normal treatment operations or should treatment not function efficiently due to other deficiencies, high concentrations of potentially viable, infectious oocysts may pass through the plant into finished drinking water. The recycle stream occurrence studies presented in Table II.7 are described in further detail in the following sections.

Thames, U.K. Water Utilities Experience with Cryptosporidium, Colbourne (1989)

In response to a cryptosporidiosis outbreak reported in February of 1989, Thames Water undertook an investigation of pathogen concentrations within the Farmoor conventional treatment plant's treatment train, finished and raw waters. The investigation occurred over a two month period, from February to April 1989 and included sampling of settled filter backwash, the supernatant from spent filter backwash, raw water, and water sampled at the end of various Thames distribution points.

kwash, raw water, and water sampled at the end of various Thames distribution points.

On February 19, 1989 at the start of the outbreak investigation, a concentration of approximately 1,000,000 oocysts/100L was detected in the filter backwash water. During the first few days of the following investigation, the supernatant of the settled backwash water contained approximately 100,000 oocysts/100L. At the peak of the outbreak, thirty percent of Thames' distribution system samples were positive for oocysts, and ranged in concentration from 0.2 to 7700 oocysts/100L. Raw reservoir water contained oocyst concentrations ranging from .2 to 1400 oocysts/100L. After washing the filters twice in 24 hours, no oocysts were found in the settled backwash waters. Thames, U.K. Water Utilities determined that a storm causing intense precipitation and runoff resulted in elevated levels of oocysts in the source water which led to the high concentrations of oocysts entering the plant and subsequently deposited on the filters and recycled as filter backwash.

Survey of Potable Water Supplies for Cryptosporidium and Giardia, Rose, et al., 1991

In this survey, Rose, et al., collected 257 samples from 17 States from 1985 to 1988. The samples were collected on cartridge filters and analyzed using variations of the IFA method. The reported percent recovery for the method was 29 to 58 percent. Filter backwash samples were a subset of the 257, 10 to 40 L samples were collected from rapid sand filters.

Rose, et al. reported the geometric mean of the backwash samples at 217 Cryptosporidium oocysts/100L. This was the highest reported average Cryptosporidium concentration of any of the water types tested, which included polluted and pristine surface and ground water sources, drinking water sources in addition to filter backwash recycle water.

Giardia and Cryptosporidium in Water Supplies, LeChevallier, et al. (1991c)

LeChevallier et al

f the backwash samples at 217 Cryptosporidium oocysts/100L. This was the highest reported average Cryptosporidium concentration of any of the water types tested, which included polluted and pristine surface and ground water sources, drinking water sources in addition to filter backwash recycle water.

Giardia and Cryptosporidium in Water Supplies, LeChevallier, et al. (1991c)

LeChevallier et al. conducted a study to determine “whether compliance with the SWTR would ensure control of Giardia in potable water supplies.” Raw water and plant effluent samples were collected from 66 surface water treatment plants in 14 States and one Canadian province, although only selected sites were tested for Cryptosporidium oocysts in filter backwash and settled backwash water.

In the analysis of pathogen concentrations in the raw water and filter backwash water of the water treatment process, LeChevallier et al. (1991c) found very high oocyst levels in backwash water of utilities that had low raw water parasite concentrations. The pathogens were detected using a combined IFA method that the authors developed. Cryptosporidium levels in the initial backwash water were 57 to 61 times higher than in the raw water supplies. Raw water samples were found to contain from 7 to 108 oocysts/100L. LeChevallier et al. (1991c) also noted that when Cryptosporidium were detected in plant effluent samples (12 of 13 times), the organisms were also observed in the backwash samples. The study concluded that the consistency of these results shows that accumulation of parasites in the treatment filters (and subsequent release in the filter backwash recycle water) could be related to subsequent passage through treatment barriers

also noted that when Cryptosporidium were detected in plant effluent samples (12 of 13 times), the organisms were also observed in the backwash samples. The study concluded that the consistency of these results shows that accumulation of parasites in the treatment filters (and subsequent release in the filter backwash recycle water) could be related to subsequent passage through treatment barriers.

Recycle Stream Effects on Water Treatment, Cornwell and Lee (1993, 1994)

The results described in Cornwell and Lee's 1993 American Water Works Association Research Foundation Report and 1994 Journal of the American Water Works Association article on the Bangor and Moshannon Valley, PA water treatment plants are consistent with the results of States et al. (1997). In total, Cornwell and Lee investigated eight water treatment plants, examining treatment efficiencies including several recycle streams and their impacts, and reporting a range of pathogen and other water quality data. All of the pathogen testing was conducted using the EPA IFA method refined by LeChevallier, et al. (1991c).

Cornwell and Lee (1993) conducted two rounds of sampling at both the Bangor and Moshannon plants, sampling the different recycle and treatment streams as eight-hour composites. They detected Cryptosporidium concentrations of over 16,500 Cryptosporidium oocysts/100L in the backwash water at an adsorption clarifier plant (Moshannon Valley) and over 850 Cryptosporidium oocysts/100L in backwash water from a direct filtration plant (Bangor). The parasite levels in the backwash samples were significantly higher than concentrations found in the raw source water, which contained Cryptosporidium oocyst concentrations of 13-20 oocysts/100L at the Moshannon Valley plant and 6-140 oocysts/100L at the Bangor plant.

In addition, Cornwell and Lee determined oocyst concentrations for two other recycle streams, combined thickener supernatant and sedimentation basin solids

ackwash samples were significantly higher than concentrations found in the raw source water, which contained Cryptosporidium oocyst concentrations of 13-20 oocysts/100L at the Moshannon Valley plant and 6-140 oocysts/100L at the Bangor plant.

In addition, Cornwell and Lee determined oocyst concentrations for two other recycle streams, combined thickener supernatant and sedimentation basin solids. The supernatant pathogen concentrations were reported at 141 Cryptosporidium oocysts/100L at the Bangor plant, and levels were reported at 82 to 420 oocysts/100L for the Moshannon plant in Rounds 1 and 2 of sampling, respectively. The sedimentation basin sludge was reported at 2,642 Cryptosporidium oocysts/100L in the clarifier sludge from the Moshannon Valley plant.

Giardia and Cryptosporidium in Backwash Water from Rapid Sand Filters Used for Drinking Water, Karanis et al. (1996) and Distribution and Removal of Giardia and Cryptosporidium in Water Supplies in Germany Karanis, et al. (1998)

Karanis et al. (1996 and 1998) conducted a four-year research study (samples collected from July, 1993-December, 1995) on the efficiency of Cryptosporidium removal by six different surface water treatment plants from Germany, all of which treat by conventional filtration. The method used was an IFA method dubbed the “EPA method”, developed by Jakubowski and Ericksen, 1979.

Karanis et al. (1996) detected Cryptosporidium in 82 percent of the samples of backwash water from rapid sand filters of a water treatment plant (“Plant C”) supplied by small rivers. Eight out of 12 raw water samples tested were positive for Cryptosporidium (range of 0.8 to 109 oocysts/100L). Backwash water samples collected by continuous flow centrifugation were positive for Cryptosporidium in 8 of 11 samples (range of 1 to 69/100L). Of 39 samples collected using cartridge filters, 33 were positive for Cryptosporidium (range of 0.8 to 252/100L)

t C”) supplied by small rivers. Eight out of 12 raw water samples tested were positive for Cryptosporidium (range of 0.8 to 109 oocysts/100L). Backwash water samples collected by continuous flow centrifugation were positive for Cryptosporidium in 8 of 11 samples (range of 1 to 69/100L). Of 39 samples collected using cartridge filters, 33 were positive for Cryptosporidium (range of 0.8 to 252/100L). The authors called attention to the high detection rate of Cryptosporidium in the backwash waters (82 percent) of Plant C and to the fact that the supernatant following sedimentation was not free from cysts and oocysts (Karanis et al. 1996).

In the 1998 publication, Karanis et al. compiled the data from the 1996 study with more backwash occurrence data collected from another treatment plant (“Plant A”). The filter backwash of Plant A was sampled 10 minutes after the start of backwashing, and the backwash water was found to contain 150 Cryptosporidium oocysts/100L.

Protozoa in River Water: Sources, Occurrence, and Treatment, States, et al. (1997)

Over a two year period (July, 1994-June, 1996), States et al. sampled monthly for Cryptosporidium in the raw, settled, filtered and filter backwash water at the Pittsburgh Drinking Water Treatment Plant, in order to gauge the efficiency of pathogen removal at the plant. States et al. identified several sources contributing oocysts to the influent water, including sewage plant effluent, combined sewer overflows, dairy farm streams, and recycling of backwash water. All pathogen sampling was conducted with the IFA method.

Cryptosporidium occurred in the raw Allegheny river water supplying the plant with a geometric mean of 31 oocysts/100L in 63 percent of samples collected, and ranged from non-detect to 2,333 oocysts/100L (see Table II.3 for source water information). Of the filter backwash samples, a geometric mean of 328 oocysts/100L was found at an occurrence rate of 38 percent of samples, with a range from non-detect to 13,158 oocysts/100L

he raw Allegheny river water supplying the plant with a geometric mean of 31 oocysts/100L in 63 percent of samples collected, and ranged from non-detect to 2,333 oocysts/100L (see Table II.3 for source water information). Of the filter backwash samples, a geometric mean of 328 oocysts/100L was found at an occurrence rate of 38 percent of samples, with a range from non-detect to 13,158 oocysts/100L. The fact that the mean concentration of Cryptosporidium oocysts in backwash water can be substantially higher than the oocyst concentration in untreated river water suggests that recycling untreated filter backwash water can be a significant source of this parasite to water within the treatment process.

F. Summary and Conclusions

Cryptosporidiosis is a disease without a therapeutic cure, and its causative agent, Cryptosporidium , is resistant to chlorine disinfection. Cryptosporidium has been known to cause severe illness, especially in immunocompromised individuals, and can be fatal. Several waterborne cryptosporidiosis outbreaks have been reported, and it is likely that others have occurred but have gone unreported. Cryptosporidium has been detected in a wide range of source waters, documented in over 30 studies from the literature, and it has been found at levels of concern in filter backwash water and other recycle streams.

One of the key regulations EPA has developed and implemented to counter pathogens in drinking water is the SWTR (54 FR 27486, June 19, 1989). The SWTR requires that surface water systems have sufficient treatment to reduce the source water concentration of Giardia and viruses by at least 99.9 percent (3 log) and 99.99 percent (4 log), respectively. A shortcoming of the SWTR, however, is that the rule does not specifically control for Cryptosporidium . The first report of a recognized waterborne outbreak caused by Cryptosporidium was published during the development of the SWTR (D'Antonio et al. 1985)

tment to reduce the source water concentration of Giardia and viruses by at least 99.9 percent (3 log) and 99.99 percent (4 log), respectively. A shortcoming of the SWTR, however, is that the rule does not specifically control for Cryptosporidium . The first report of a recognized waterborne outbreak caused by Cryptosporidium was published during the development of the SWTR (D'Antonio et al. 1985).

In 1998, the Agency finalized the IESWTR that enhances the microbial pathogen protection provided by the SWTR for systems serving 10,000 or more persons. The IESWTR includes an MCLG of zero for Cryptosporidium and requires a minimum 2-log (99 percent) removal of Cryptosporidium , linked to enhanced combined filter effluent and individual filter turbidity control provisions.

Several provisions of today's proposed rule, the LT1FBR, are designed to address the concerns covered by the IESWTR, improving control of Cryptosporidium and other microbial contaminants, for the portion of the public served by small PWSs (i.e., serving less than 10,000 persons). The LT1FBR also addresses the concern that for all PWSs that practice recycling, Cryptosporidium (and other emerging pathogens resistant to standard disinfection practice) are reintroduced to the treatment process of PWSs by the recycle of spent filter backwash water, solids treatment residuals, and other process streams.

Insufficient treatment practices have been cited as the cause of several reported waterborne disease outbreaks (Rose, 1997). Rose (1997) also found that a reduction in turbidity is indicative of a more efficient filtration process. Therefore, the turbidity and filter monitoring requirements of today's proposed LT1FBR will ensure that the removal process necessary to protect the public from cryptosporidiosis is operating properly, and the recycle stream provisions will ensure that the treatment process is not disrupted or operating inefficiently

at a reduction in turbidity is indicative of a more efficient filtration process. Therefore, the turbidity and filter monitoring requirements of today's proposed LT1FBR will ensure that the removal process necessary to protect the public from cryptosporidiosis is operating properly, and the recycle stream provisions will ensure that the treatment process is not disrupted or operating inefficiently. The LT1FBR requirements that address the potential for Cryptosporidium to enter the finished drinking water supply will be described in more detail in the following sections.

III. Baseline Information-Systems Potentially Affected By Today's Proposed Rule

EPA utilized the 1997 state-verified version of the Safe Drinking Water Information System (SDWIS) to develop the total universe of systems which utilize surface water or groundwater under the direct influence (GWUDI) as sources. This universe consists of 11,593 systems serving fewer than 10,000 persons, and 2,096 systems serving 10,000 or more persons. Given this initial baseline, the Agency developed estimates of the number of systems which would be affected by components of today's proposed rule by utilizing three primary sources: Safe Drinking Water Information Systems; Community Water Supply Survey; and Water: Stats. A brief overview of each of the data sources is described in the following paragraphs.

Safe Drinking Water Information System (SDWIS)

SDWIS contains information about PWSs including violations of EPA's regulations for safe drinking water. Pertinent information in this database includes system name and ID, population served, geographic location,

Community Water System Survey (CWSS)

EPA conducted the 1995 CWSS to obtain data to support its development and evaluation of drinking water regulations. The survey consisted of a stratified random sample of 3,700 water systems nationwide (surface water and groundwater). The survey asked 24 operational and 13 financial questions

cludes system name and ID, population served, geographic location,

Community Water System Survey (CWSS)

Water:/Stats (WaterStats)

WaterStats is an in-depth database of water utility information compiled by the American Water Works Association. The database consists of 898 utilities of all sizes and provides a variety of data including treatment information.

Information regarding estimates of the number of systems which may potentially be affected by specific components of today's proposed rule can be found in the discussion of each proposed rule component in Section IV.

IV. Discussion of Proposed LT1FBR Requirements

A. Enhanced Filtration Requirements

As discussed earlier in this preamble, one of the key objectives of today's proposed rule is ensuring that an adequate level of public health protection is maintained in order to minimize the risk associated with Cryptosporidium . While the current SWTR provides protection from viruses and Giardia , it does not specifically address Cryptosporidium , which has been linked to outbreaks resulting in over 420,000 cases of gastrointestinal illness in the 1990s (403,000 associated with the Milwaukee outbreak). Because of Cryptosporidium 's resistance to disinfection practices currently in place at small systems throughout the country, the Agency believes enhanced filtration requirements are necessary to improve control of this microbial pathogen.

at small systems throughout the country, the Agency believes enhanced filtration requirements are necessary to improve control of this microbial pathogen.

In the IESWTR, the Agency utilized an approach consisting of three major components to address Cryptosporidium at plants serving populations of 10,000 or more. The first component required systems to achieve a 2 log removal of Cryptosporidium . The second component consisted of strengthened turbidity requirements for combined filter effluent. The third component required individual filter turbidity monitoring.

In today's proposed rule addressing systems serving fewer than 10,000 persons, the Agency is utilizing the same framework. Where appropriate, EPA has evaluated additional options in an effort to alleviate burden on small systems while still maintaining a comparable level of public health protection.

The following sections describe the overview and purpose of each of the rule components, relevant data utilized during development, the requirements of today's proposed rule (including consideration of additional options where appropriate), and a request for comment regarding each component.

1. Two Log Cryptosporidium Removal Requirement

a. Two Log Removal

i. Overview and Purpose

The 1998 IESWTR (63 FR 69477, December 16, 1998) establishes an MCLG of zero for Cryptosporidium in order to adequately protect public health. In conjunction with the MCLG, the IESWTR also established a treatment technique requiring 2 log Cryptosporidium removal for all surface water and GWUDI systems which filter and serve populations of 10,000 or more people, because it was not economically and technologically feasible to accurately ascertain the level of Cryptosporidium using current analytical methods. The Agency believes it is appropriate and necessary to extend this treatment technique of 2 log Cryptosporidium removal requirement to systems serving fewer than 10,000 people.

I systems which filter and serve populations of 10,000 or more people, because it was not economically and technologically feasible to accurately ascertain the level of Cryptosporidium using current analytical methods. The Agency believes it is appropriate and necessary to extend this treatment technique of 2 log Cryptosporidium removal requirement to systems serving fewer than 10,000 people.

ii. Data

As detailed later in this section, EPA believes that the data and principles supporting requirements established for systems serving populations of 10,000 or more are also applicable to systems serving populations fewer than 10,000. The following section provides information and data regarding: (1) the estimated number of small systems subject to the proposed 2 log Cryptosporidium removal requirement; and (2) Cryptosporidium removal using various filtration technologies.

Estimate of the Number of Systems Subject to 2 log Cryptosporidium Removal Requirement

Using the baseline described in Section III of today's proposed rule, the Agency applied percentages of surface water and GWUDI systems which filter (taken from the 1995 CWSS) in order to develop an estimate of the number of systems which filter and serve fewer than 10,000 persons. This resulted in an estimated 9,133 surface water and GWUDI systems that filter which may be subject to the proposed removal requirement. Table IV.1 provides this estimate broken down by system size and type.

Table IV.1.—Estimate of Systems Subject to 2 Log Cryptosporidium Removal Requirement a System type Population served <100 101-500 501-1K b 1K-3.3K b 3.3K-10K b Total #Sys

an 10,000 persons. This resulted in an estimated 9,133 surface water and GWUDI systems that filter which may be subject to the proposed removal requirement. Table IV.1 provides this estimate broken down by system size and type.

Table IV.1.—Estimate of Systems Subject to 2 Log Cryptosporidium Removal Requirement a System type Population served <100 101-500 501-1K b 1K-3.3K b 3.3K-10K b Total #Sys. Community 888 1453 950 2022 1591 6903 Non Community 1099 374 78 64 35 1649 NTNC 214 204 82 64 17 581 Total 2201 2031 1110 2150 1643 b 9134b a Numbers may not add due to rounding b K = thousands Cryptosporidium Removal Using Conventional and Direct Filtration

During development of the LT1FBR, the Agency reviewed the results of several studies that demonstrated the ability of conventional and direct filtration systems to achieve 2 log removal of Cryptosporidium at well operated plants achieving low turbidity levels. Table IV.2 provides key information from these studies. A brief description of each study follows the table.

Table IV.2.—Conventional and Direct Filtration Removal Studies Type of treatment Log removal Experimental design Researcher Conventional Cryptosporidium 4.2-5.2 Pilot plants Patania et al. 1995 Giardia 4.1-5.1 Pilot plants Patania et al. 1995 Cryptosporidium 1.9-4.0 Pilot-scale plants Nieminski/Ongerth 1995 Giardia 2.2-3.9 Pilot-scale plants Nieminski/Ongerth 1995 Cryptosporidium 1.9-2.8 Full-scale plants Nieminski/Ongerth 1995 Giardia 2.8-3.7 Full-scale plants Nieminski/Ongerth 1995 Cryptosporidium 2.3-2.5 Full-scale plants LeChevallier and Norton 1992 Giardia 2.2-2.8 Full-scale plants Cryptosporidium 2-3 Pilot plants LeChevallier and Norton 1992 Giardia and Crypto 1.5-2 Full-scale plant (operation considered not optimized) Foundation for Water Research, Britain 1994 Cryptosporidium 4.1-5.2 Pilot Plant (optimal treatment) Kelley et al. 1995 Cryptosporidum .2-1.7 Pilot Plant (suboptimal treatment) Dugan et al. 1999 Dugan et al

ier and Norton 1992 Giardia 2.2-2.8 Full-scale plants Cryptosporidium 2-3 Pilot plants LeChevallier and Norton 1992 Giardia and Crypto 1.5-2 Full-scale plant (operation considered not optimized) Foundation for Water Research, Britain 1994 Cryptosporidium 4.1-5.2 Pilot Plant (optimal treatment) Kelley et al. 1995 Cryptosporidum .2-1.7 Pilot Plant (suboptimal treatment) Dugan et al. 1999 Dugan et al. 1999 Direct filtration Cryptosporidium 2.7-3.1 Pilot plants Ongerth/Pecaroro 1995 Giardia 3.1-3.5 Pilot plants Ongerth/Pecaroro 1995 Cryptosporidium 2.7-5.9 Pilot plants Patania et al. 1995 Giardia 3.4-5.0 Pilot plants Patania et al. 1995 Cryptosporidium 1.3-3.8 Pilot plants Nieminski/Ongerth 1995 Giardia 2.9-4.0 Pilot plants Nieminski/Ongerth 1995 Cryptosporidium 2-3 Pilot plants West et al. 1994 Rapid Granular Filtration (alone) Cryptosporidium 2.3-4.9 Pilot plant Swertfeger et al. , 1998 Giardia 2.7-5.4 Patania, Nancy L, et al. 1995

This study consisted of four pilot studies which evaluated treatment variables for their impact on Cryptosporidium and Giardia removal efficiencies. Raw water turbidities in the study ranged between 0.2 and 13 NTU. When treatment conditions were optimized for turbidity and particle removal at four different sites, Cryptosporidium removal ranged from 2.7 to 5.9 log and Giardia removal ranged from 3.4 to 5.1 log during stable filter operation. The median turbidity removal was 1.4 log, whereas the median particle removal was 2 log. Median oocyst and cyst removal was 4.2 log. A filter effluent turbidity of 0.1 NTU or less resulted in the most effective cyst removal, up to 1 log greater than when filter effluent turbidities were greater than 0.1 NTU (within the 0.1 to 0.3 NTU range). Cryptosporidium removal rates of less than 2.0 log occurred at the end of the filtration cycle.

Nieminski, Eva C. and Ongerth, Jerry E. 1995

This 2-year study evaluated Giardia and Cryptosporidium cyst removal through direct and conventional filtration

effective cyst removal, up to 1 log greater than when filter effluent turbidities were greater than 0.1 NTU (within the 0.1 to 0.3 NTU range). Cryptosporidium removal rates of less than 2.0 log occurred at the end of the filtration cycle.

Nieminski, Eva C. and Ongerth, Jerry E. 1995

This 2-year study evaluated Giardia and Cryptosporidium cyst removal through direct and conventional filtration. The source water of the full scale plant had turbidities typically between 2.5 and 11 NTU with a maximum of 28 NTU. The source water of the pilot plant typically had turbidities of 4 NTU with a maximum of 23 NTU. For the pilot plant achieving filtered water turbidities between 0.1-0.2 NTU, Cryptosporidium removals averaged 3.0 log for conventional treatment and 3.0 log for direct filtration, while the respective Giardia removals averaged 3.4 log and 3.3 log. For the full scale plant achieving similar filtered water turbidities, Cryptosporidium removal averaged 2.25 log for conventional treatment and 2.8 log for direct filtration, while the respective Giardia removals averaged 3.3 log for conventional treatment and 3.9 log for direct filtration. Differences in performance between direct filtration and conventional treatment by the full scale plant were attributed to differences in source water quality during the filter runs.

Ongerth, Jerry E. and Pecaroro, J.P. 1995

A 1 gallon per minute (gpm) pilot scale water filtration plant was used to measure removal efficiencies of Cryptosporidium and Giardia using very low turbidity source waters (0.35 to 0.58 NTU). With optimal coagulation, 3 log removal for both pathogens were obtained. In one test run, where coagulation was intentionally sub-optimal, the removals were only 1.5 log for Cryptosporidium and 1.3 log for Giardia . This demonstrates the importance of proper coagulation for cyst removal even though the effluent turbidity was less than 0.5 NTU.

LeChevallier, Mark W. and Norton, William D

8 NTU). With optimal coagulation, 3 log removal for both pathogens were obtained. In one test run, where coagulation was intentionally sub-optimal, the removals were only 1.5 log for Cryptosporidium and 1.3 log for Giardia . This demonstrates the importance of proper coagulation for cyst removal even though the effluent turbidity was less than 0.5 NTU.

LeChevallier, Mark W. and Norton, William D. 1992

The purpose of this study was to evaluate the relationships among Giardia , Cryptosporidium , turbidity, and particle counts in raw water and filtered water effluent samples at three different systems. Source water turbidities ranged from less than 1 to 120 NTU. Removals of Giardia and Cryptosporidium (2.2 to 2.8 log) were slightly less than those reported by other researchers, possibly because full scale plants were studied under less ideal conditions than the pilot plants. The participating treatment plants operated within varying stages of treatment optimization. The median removal achieved was 2.5 log for Cryptosporidium and Giardia .

LeChevallier, Mark W.; Norton, William D.; and Lee, Raymond G. 1991b

This study evaluated removal efficiencies for Giardia and Cryptosporidium in 66 surface water treatment plants in 14 States and 1 Canadian province. Most of the utilities achieved between 2 and 2.5 log removals for both Giardia and Cryptosporidium . When no oocysts were detected in the finished water, occurrence levels were assumed at the detection limit for calculating removal efficiencies.

Foundation for Water Research 1994

This study evaluated Cryptosporidium removal efficiencies for several treatment processes (including conventional filtration) using a pilot plant and bench-scale testing. Raw water turbidity ranged from 1 to 30 NTU. Cryptosporidium oocyst removal was between 2 and 3 log using conventional filtration. Investigators Cryptosporidium , and also showed the importance of selecting proper coagulants, dosages, and treatment pH

ryptosporidium removal efficiencies for several treatment processes (including conventional filtration) using a pilot plant and bench-scale testing. Raw water turbidity ranged from 1 to 30 NTU. Cryptosporidium oocyst removal was between 2 and 3 log using conventional filtration. Investigators Cryptosporidium , and also showed the importance of selecting proper coagulants, dosages, and treatment pH. In addition to turbidity, increased color and dissolved metal ion coagulant concentration in the effluent are indicators of reduced efficiency of coagulation/flocculation and possible reduced oocysts removal efficiency.

Kelley, M.B. et al. 1995

This study evaluated two U.S. Army installation drinking water treatment systems for the removal of Giardia and Cryptosporidium . Protozoa removal was between 1.5 and 2 log. The authors speculated that this low Cryptosporidium removal efficiency occurred because the coagulation process was not optimized, although the finished water turbidity was less than 0.5 NTU.

West, Thomas; et al. 1994

This study evaluated the removal efficiency of Cryptosporidium through direct filtration using anthracite mono-media at filtration rates of 6 and 14 gpm/sq.ft. Raw water turbidity ranged from 0.3 to 0.7 NTU. Removal efficiencies for Cryptosporidium at both filtration rates were 2 log during filter ripening (despite turbidity exceeding 0.2 NTU), and 2 to 3 log for the stable filter run. Log removal declined significantly during particle breakthrough. When effluent turbidity was less than 0.1 NTU, removal typically exceeded 2 log. Log removals of Cryptosporidium generally exceeded that for particle removal.

Swertfeger et al., 1998

The Cincinnati Water Works conducted a 13 month pilot study to determine the optimum filtration media and depth of the media to replace media at its surface water treatment plant

ntly during particle breakthrough. When effluent turbidity was less than 0.1 NTU, removal typically exceeded 2 log. Log removals of Cryptosporidium generally exceeded that for particle removal.

Swertfeger et al., 1998

The Cincinnati Water Works conducted a 13 month pilot study to determine the optimum filtration media and depth of the media to replace media at its surface water treatment plant. The study investigated cyst and oocyst removal through filtration alone (excluding chemical addition, mixing, or sedimentation) and examined sand media, dual media, and deep dual media. Cyst and oocyst removal by each of the media designs was > 2.5 log by filtration alone.

Dugan et al., 1999

EPA conducted pilot scale experiments to assess the ability of conventional treatment to control Cryptosporidium oocysts under steady state conditions. The work was performed with a pilot plant designed to minimize flow rates and the number of oocysts required for spiking. With proper coagulation control, the conventional treatment process achieved at least 2 log removal of Cryptosporidium . In all cases where 2 log removal was not achieved, the plant also did not comply with the IESWTR filter effluent turbidity requirements.

All of the studies described above indicate that rapid granular filtration, when operated under appropriate coagulation conditions and optimized to achieve a filtered water turbidity level of less than 0.3 NTU, should achieve at least 2 log of Cryptosporidium removal. Removal rates vary widely, up to almost 6 log, depending upon water matrix conditions, filtered water turbidity effluent levels, and where and when removal efficiencies are measured within the filtration cycle. The highest log pathogen removal rates occurred in those pilot plants and systems which achieved very low finished water turbidities (less than 0.1 NTU). Other key points related to the studies include:

• As turbidity performance improves for treatment of a particular water, there tends to be greater removal of Cryptosporidium

when removal efficiencies are measured within the filtration cycle. The highest log pathogen removal rates occurred in those pilot plants and systems which achieved very low finished water turbidities (less than 0.1 NTU). Other key points related to the studies include:

• As turbidity performance improves for treatment of a particular water, there tends to be greater removal of Cryptosporidium .

• Pilot plant study data in particular indicate high likelihood of achieving at least 2 log removal when plant operation is optimized to achieve low turbidity levels. Moreover, pilot studies represented in Table IV.2.a tend to be for low-turbidity waters, which are considered to be the most difficult to treat regarding particulate removal and associated protozoan removal.

• Because high removal rates were demonstrated in pilot studies using lower-turbidity source waters, it is likely that similar or higher removal rates can be achieved for higher-turbidity source waters.

• Determining Cryptosporidium removal in full-scale plants can be difficult due to the fact that data includes many non-detects in the finished water. In these cases, finished water concentration levels are assigned at the detection limit and are likely to result in over-estimation of oocysts in the finished water. This tends to under-estimate removal levels.

s are assigned at the detection limit and are likely to result in over-estimation of oocysts in the finished water. This tends to under-estimate removal levels.

• Another factor that contributes to differences among the data is that some of the full-scale plant data comes from plants that are not optimized, but meet existing SWTR requirements. In such cases, oocyst removal may be less than 2 log. In those studies that indicate that full-scale plants are achieving greater than 2 log removal (LeChevallier studies in particular), the following characteristics pertain:

—Substantial numbers of filtered water measurements resulted in oocyst detections; —Source water turbidity tended to be relatively high compared to some of the other studies; and —A significant percentage of these systems were also achieving low filtered water turbidities, substantially less than 0.5 NTU. •Removal of Cryptosporidium can vary significantly in the course of the filtration cycle (i.e., at the start-up and end of filter operations versus the stable period of operation).

Cryptosporidium Removal Using Slow Sand and Diatomaceous Earth Filtration

During development of the IESWTR, the Agency also evaluated several studies which demonstrated that slow sand and diatomaceous earth filtration were capable of achieving at least 2 log removal of Cryptosporidium . Table IV.3 provides key information from these studies. A brief description of each study follows the table.

Table IV.3.—Slow Sand and Diatomaceous Earth Filtration Removal Studies Type of treatment Log removal Experimental design Researcher Slow-sand filtration Giardia & Cryptosporidium > 3 Cryptosporidium 4.5 Pilot plant at 4.5 to 16.5°C. Full-scale plant Shuler and Ghosh 1991. imms et. al. 1995. Diatomaceous earth filtration Giardia & Cryptosporidium > 3 Cryptosporidium 3.3-6.68 Pilot plant, Bench scale Shuler et. al. 1990. Ongerth & Hutton, 1997

iltration Removal Studies Type of treatment Log removal Experimental design Researcher Slow-sand filtration Giardia & Cryptosporidium > 3 Cryptosporidium 4.5 Pilot plant at 4.5 to 16.5°C. Full-scale plant Shuler and Ghosh 1991. imms et. al. 1995. Diatomaceous earth filtration Giardia & Cryptosporidium > 3 Cryptosporidium 3.3-6.68 Pilot plant, Bench scale Shuler et. al. 1990. Ongerth & Hutton, 1997. Shuler and Ghosh 1991

This pilot study was conducted to evaluate the ability of slow sand filters to remove Giardia , Cryptosporidium , coliforms, and turbidity. The pilot study was conducted at Pennsylvania State University using a raw water source with a turbidity ranging from 0.2-0.4 NTU. Influent concentration of Cryptosporidium oocysts during the pilot study ranged from 1,300 to 13,000 oocysts/gallon. Oocyst removal was shown to be greater than 4 log.

Timms et al 1995

This pilot study was conducted to evaluate the efficiency of slow sand filters at removing Cryptosporidium . A pilot plant was constructed of 1.13 m 2 in area and 0.5 m in depth with a filtration rate of 0.3m/h. The filter was run for 4-5 weeks before the experiment to ensure proper operation. Cryptosporidium oocysts were spiked to a concentration of 4,000/L. Results of the study indicated a 4.5 log removal of Cryptosporidium oocysts.

Shuler et al 1990

In this study, diatomaceous earth (DE) filtration was evaluated for removal of Giardia , Cryptosporidium , turbidity and coliform bacteria. The study used a 0.1m 2 pilot scale DE filter with three grades of diatomaceous earth (A, B, and C). The raw water turbidity varied between 0.1 and 1 NTU. Filter runs ranged from 2 days to 34 days. A greater than 3 log removal of Cryptosporidium was demonstrated in the 9 filter runs which made up the study.

Ongerth and Hutton, 1997

Bench scale studies were used to define basic characteristics of DE filtration as a function of DE grade and filtration rate. Three grades of DE were used in the tests

raw water turbidity varied between 0.1 and 1 NTU. Filter runs ranged from 2 days to 34 days. A greater than 3 log removal of Cryptosporidium was demonstrated in the 9 filter runs which made up the study.

Ongerth and Hutton, 1997

Bench scale studies were used to define basic characteristics of DE filtration as a function of DE grade and filtration rate. Three grades of DE were used in the tests. Cryptosporidium removal was measured by applying river water seeded with Cryptosporidium to Walton test filters. Tests were run for filtration rates of 1 and 2 gpm/sq ft. Each run was replicated 3 times. Approximately 6 logs reduction in the concentration of Cryptosporidium oocysts was expected under normal operating conditions.

Cryptosporidium Removal Using Alternative Filtration Technologies

EPA recognizes that systems serving fewer than 10,000 individuals employ a variety of filtration technologies other than those previously discussed. EPA collected information regarding several other popular treatment techniques in an effort to verify that these treatments were also technically capable of achieving a 2 log removal of Cryptosporidium . A brief discussion of these alternative technologies follows along with studies demonstrating effective Cryptosporidium removals.

Membrane Filtration

Membrane filtration (Reverse Osmosis, Nanofiltration, Ultrafiltration, and Microfiltration) relies upon pore size in order to remove particles from water. Membranes possess a pore size smaller than that of a Cryptosporidium oocyst, enabling them to achieve effective log removals. The smaller the pore size, the more effective the rate of removal. Typical pore sizes for each of the four types of membrane filtration are shown below:

• Microfiltration—1-0.1 microns ( μ m)

• Ultrafiltration—0.1-.01 ( μ m)

• Nanofiltration—.01-.001 ( μ m)

• Reverse Osmosis—<.001 ( μ m)

Bag Filtration

Bag filters are non-rigid, disposable, fabric filters where water flows from inside of the bag to the outside of the bag

effective the rate of removal. Typical pore sizes for each of the four types of membrane filtration are shown below:

• Microfiltration—1-0.1 microns ( μ m)

• Ultrafiltration—0.1-.01 ( μ m)

• Nanofiltration—.01-.001 ( μ m)

• Reverse Osmosis—<.001 ( μ m)

Bag Filtration

Bag filters are non-rigid, disposable, fabric filters where water flows from inside of the bag to the outside of the bag. One or more filter bags are contained within a pressure vessel designed to facilitate rapid change of the filter bags when the filtration capacity has been used up. Bag filters do not generally employ any chemical coagulation. The pore sizes in the filter bags designed for protozoa removal generally are small enough to remove protozoan cysts and oocysts but large enough that bacteria, viruses and fine colloidal clays would pass through. Bag filter studies have shown a significant range of results in the removal of Cryptosporidium oocysts (0.33-3.2 log). (Goodrich, 1995)

Cartridge Filtration

Cartridge filtration also relies on physical screening to remove particles from water. Typical cartridge filters are pressure filters with glass, fiber or ceramic membranes, or strings wrapped around a filter element housed in a pressure vessel (USEPA, 1997a).

The Agency evaluated several studies which demonstrate the ability of various alternative filtration technologies to achieve 2 log removal of Cryptosporidium ( in several studies 2 log removal of 4-5 ( μ m) microspheres were used as a surrogate for Cryptosporidium ). These studies demonstrate that 2 log removal was consistently achievable in all but bag filters. Table IV.4 provides key information from these studies. A brief description of each study follows:

Table IV.4.—Alternative Filtration Removal Studies Type of treatment Log removal Experimental design Researcher Microfiltration Cryptosporidium 4.2-4.9 log Bench Scale Jacangelo et al. 1997

sporidium ). These studies demonstrate that 2 log removal was consistently achievable in all but bag filters. Table IV.4 provides key information from these studies. A brief description of each study follows:

Table IV.4.—Alternative Filtration Removal Studies Type of treatment Log removal Experimental design Researcher Microfiltration Cryptosporidium 4.2-4.9 log Bench Scale Jacangelo et al. 1997. Giardia 4.6-5.2 log Cryptosporidium 6.0—7.0 log Pilot Plant Cryptosporidium 4.3—5.0 log Pilot Plant Drozd & Schartzbrod, 1997. Cryptosporidium 7.0-7.7 log Bench Scale Hirata & Hashimoto, 1998. Microspheres 3.57-3.71 log Full Scale Goodrich et al. 1995. Ultrafiltration Cryptosporidium 4.4—4.9 log Bench Scale Jacangelo et al. 1997. Giardia 4.7-5.2 log Cryptosporidium 5.73-5.89 log Bench Scale Collins et al. 1996. Giardia 5.75-5.85 log Cryptosporidium 7.1-7.4 log Bench Scale Hirata & Hashimoto, 1998. Cryptosporidium 3.5 log pilot Plant Lykins et al. 1994. Microspheres 3-4 log Reverse Osmosis Cryptosporidium > 5.7 log Pilot Scale Adham et al. 1998 Giardia > 5.7 log Hybrid Membrane Microspheres 4.18 log Bench Scale Goodrich et al. 1995 Bag Filtration Microspheres .33-3.2 log Pilot Plant Goodrich et al. 1995 Cartridge filtration Microspheres 3.52-3.68 log Particles (5-15 um) > 2 log Pilot Plant Bench Scale Goodrich et al. 1995 Land, 1998. Jacangelo et al., 1997

Bench scale and pilot plant tests were conducted with microfiltration and ultrafiltration filters (using six different membranes) in order to evaluate microorganism removal. Bench scale studies were conducted under worst case operating conditions (direct flow filtration at the maximum recommended transmembrane pressure using deionized water slightly buffered at pH 7). Log removal ranged from 4.7 to 5.2 log removal. Pilot plant results ranged from 6.0-7.0 log removal during worst-case operating conditions ( i.e., direct filtration immediately after backwashing at the maximum recommended operating transmembrane pressure)

operating conditions (direct flow filtration at the maximum recommended transmembrane pressure using deionized water slightly buffered at pH 7). Log removal ranged from 4.7 to 5.2 log removal. Pilot plant results ranged from 6.0-7.0 log removal during worst-case operating conditions ( i.e., direct filtration immediately after backwashing at the maximum recommended operating transmembrane pressure).

Drozd and Schartzbrod, 1997

A pilot plant system was established to evaluate the removal of Cryptosporidium using crossflow microfiltration (.2 μ m porosity). Results demonstrated Cryptosporidium log removals of 4.3 to greater than 5.5 with a corresponding mean filtrate turbidity of 0.25 NTU.

Collins et. al., 1996

This study consisted of bench scale testing of Cryptosporidium and Giardia log removals using an ultrafiltration system. Log removal of Cryptosporidium ranged from 5.73 to 5.89 log, while removal of Giardia ranged from 5.75 to 5.85 log.

Hirata & Hashimoto, 1998

Pilot scale testing using microfiltration (nominal pore size of .25 μ m) and ultrafiltration (nominal cut-off molecular weight (MW) 13,000 daltons) was conducted to determine Cryptosporidium oocyst removal. Results conducted on the ultrafiltration units ranged from 7.1 to 7.5 logs of Cryptosporidium removal. Results of the microfiltration studies yielded log removals from 7.0 to 7.7 log.

Lykins et al., [1994]

An ultrafiltration system was evaluated for the removal of Cryptosporidium oocysts at the USEPA Test and Evaluation Facility in Cincinnati, Ohio. The filter run was just over 48 hours. A 3.5 log removal of Cryptosporidium oocysts was observed. Additionally, twenty-four experiments were performed using 4.5 μ m polystyrene microspheres as a surrogate for Cryptosporidium because of a similar particle distribution. Log removal of microspheres ranged from 3 to 4 log.

Adham et al., 1998

This study was conducted to evaluate monitoring methods for membrane integrity

t over 48 hours. A 3.5 log removal of Cryptosporidium oocysts was observed. Additionally, twenty-four experiments were performed using 4.5 μ m polystyrene microspheres as a surrogate for Cryptosporidium because of a similar particle distribution. Log removal of microspheres ranged from 3 to 4 log.

Adham et al., 1998

This study was conducted to evaluate monitoring methods for membrane integrity. In addition to other activities, microbial challenge tests were conducted on reverse osmosis (RO) membranes to both determine log removals and evaluate system integrity. Log removal of Cryptosporidium and Giardia was >5.7 log in uncompromised conditions, and > 4.5 log in compromised conditions.

Goodrich et al., 1995

This study was conducted to evaluate removal efficiencies of three different bag filtration systems. Average filter pore size of the filters was 1 μm while surface area ranged from 35 to 47 sq ft. Bags were operated at 25, 50 and 100 percent of their maximum flow rate while spiked with 4.5 m m polystyrene microspheres (beads) as a surrogate for Cryptosporidium . Bead removal ranged from .33 to 3.2 log removal.

Goodrich et al 1995.

This study evaluated a cartridge filter with a 2 m m rating and 200 square feet of surface area for removal efficiency of Cryptosporidium sized particles. The filter was challenge tested with 4.5 μm polystyrene microspheres as a surrogate for Cryptosporidium . Flow was set at 25 gpm with 50 psi at the inlet. Results from two runs under the same conditions exhibited log removals of 3.52 and 3.68.

Land, 1998

An alternative technology demonstration test was conducted to evaluate the ability of a cartridge filter to achieve 2 log removal of particles in the 5 to 15 μm range. The cartridge achieved at least 2 log removal of the 5 to 25 μm particles 95 percent of the time up to a 20 psi pressure differential. The filter achieved at least 2 log removal of 5 to 15 μm particles up to 30-psi pressure differential

lternative technology demonstration test was conducted to evaluate the ability of a cartridge filter to achieve 2 log removal of particles in the 5 to 15 μm range. The cartridge achieved at least 2 log removal of the 5 to 25 μm particles 95 percent of the time up to a 20 psi pressure differential. The filter achieved at least 2 log removal of 5 to 15 μm particles up to 30-psi pressure differential.

While the studies above note that alternative filtration technologies have demonstrated in the lab the capability to achieve a 2 log removal of Cryptosporidium , the Agency believes that the proprietary nature of these technologies necessitates a more rigorous technology-specific determination be made. Given this issue, the Agency believes that its Environmental Technology Verification (ETV) Program can be utilized to verify the performance of innovative technologies. Managed by EPA's Office of Research and Development, ETV was created to substantially accelerate the entrance of new environmental technologies into the domestic and international marketplace. ETV consists of 12 pilot programs, one of which focuses on drinking water. The program contains a protocol for physical removal of microbiological and particulate contaminants, including test plans for bag and cartridge filters and membrane filters (NSF, 1999). These protocols can be utilized to determine whether a specific alternative technology can effectively achieve a 2 log removal of Cryptosporidium , and under what parameters that technology must be operated to ensure consistent levels of removal. Additional information on the ETV program can be found on the Agency's website at http://www.epa.gov/etv.

iii. Proposed Requirements

Today's proposed rule establishes a requirement for 2 log removal of Cryptosporidium for surface water and GWUDI systems serving fewer than 10,000 people that are required to filter under the SWTR

echnology must be operated to ensure consistent levels of removal. Additional information on the ETV program can be found on the Agency's website at http://www.epa.gov/etv.

iii. Proposed Requirements

Today's proposed rule establishes a requirement for 2 log removal of Cryptosporidium for surface water and GWUDI systems serving fewer than 10,000 people that are required to filter under the SWTR. Compliance with the combined filter effluent turbidity requirements, as described later, ensures compliance with the 2 log removal requirement. The requirement for a 2 log removal of Cryptosporidium applies between a point where the raw water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer.

iv. Request for Comments

EPA requests comment on the 2 log removal requirement as discussed. The Agency is also soliciting public comment and data on the ability of alternative filtration technologies to achieve 2 log Cryptosporidium removal.

2. Turbidity Requirements

a. Combined Filter Effluent

i. Overview and Purpose

In order to address concern with Cryptosporidium , EPA has analyzed log removal performance by well operated plants (as described in the previous section) as well as filter performance among small systems to develop an appropriate treatment technique requirement that assures an increased level of Cryptosporidium removal. In evaluating combined filter performance requirements, EPA considered the strengthened turbidity provisions within the IESWTR and evaluated whether these were appropriate for small systems as well.

ii. Data

In an effort to evaluate combined filter effluent (CFE) requirements, EPA collected data in several areas to

• An estimate of the number of systems subject to the proposed strengthened turbidity requirements;

• Current turbidity levels at systems throughout the U.S

thened turbidity provisions within the IESWTR and evaluated whether these were appropriate for small systems as well.

ii. Data

In an effort to evaluate combined filter effluent (CFE) requirements, EPA collected data in several areas to

• An estimate of the number of systems subject to the proposed strengthened turbidity requirements;

• Current turbidity levels at systems throughout the U.S. serving populations fewer than 10,000;

• The ability of package plants to meet strengthened turbidity standards; and

• The correlation between meeting CFE requirements and achieving 2 log removal of Cryptosporidium .

Estimate of the Number of Systems Subject to Strengthened CFE Turbidity Standards

Using the estimate of 9,134 systems which filter and serve fewer than 10,000 persons (as described in Section IV.A.1 of today's proposal), the Agency used the information contained within the CWSS database to estimate the number of systems which utilized specific types of filtration. The data was segregated based on the type of filtration utilized and the population size of the system. Percentages were derived for each of the following types of filtration:

• Conventional and Direct Filtration;

• Slow Sand Filtration;

• Diatomaceous Earth Filtration; and

• Alternative Filtration Technologies.

The percentages were applied to the estimate discussed in Section IV.A.1 of today's proposal for each of the respective population categories. Based on this analysis, the Agency estimates 5,896 conventional and direct filtration systems will be subject to the strengthened combined filter effluent turbidity standards. EPA estimates 1,756 systems utilize slow sand or diatomaceous earth filtration, and must continue to meet turbidity standards set forth in the SWTR. The remaining 1,482 systems are estimated to use alternative filtration technologies and will be required to meet turbidity standards as set forth by the State upon analysis of a 2 log Cryptosporidium demonstration conducted by the system

y standards. EPA estimates 1,756 systems utilize slow sand or diatomaceous earth filtration, and must continue to meet turbidity standards set forth in the SWTR. The remaining 1,482 systems are estimated to use alternative filtration technologies and will be required to meet turbidity standards as set forth by the State upon analysis of a 2 log Cryptosporidium demonstration conducted by the system.

Current Turbidity Levels

EPA has developed a data set which summarizes the historical turbidity performance of various filtration plants serving populations fewer than 10,000 (EPA, 1999d). The data set represents those systems that were in compliance with the turbidity requirements of the SWTR during all months being analyzed. The data set consists of 167 plants from 15 States. Table IV.5 provides information regarding the number of plants from each State. The data set includes plants representing each of the five population groups utilized in the CWSS (25-100, 101-500, 501-1,000, 1,001-3,300, and 3,301-10,000). The Agency has also received an additional data set from the State of California (EPA, 2000). This data has not been included in the assessments described below. The California data demonstrates similar results to the larger data set discussed below.

Table IV.5.—Summary of LT1FBR Turbidity Data Set State Number of Plants Alabama 1 California 1 Colorado 16 Illinois 13 Kansas 20 Louisiana 6 Minnesota 3 Montana 2 North Carolina 16 Ohio 4 Pennsylvania 27 South Carolina 16 Texas 23 Washington 17 West Virginia 2 Total 167 (EPA, 1999d) This data was evaluated to assess the national impact of modifying existing turbidity requirements. The current performance of plants was assessed with respect to the number of months in which selected 95th percentile and maximum turbidity levels were met. The data show that approximately 88 percent of systems are also currently meeting the new requirements of a maximum turbidity limit of 1 NTU (Figure IV.1)

as evaluated to assess the national impact of modifying existing turbidity requirements. The current performance of plants was assessed with respect to the number of months in which selected 95th percentile and maximum turbidity levels were met. The data show that approximately 88 percent of systems are also currently meeting the new requirements of a maximum turbidity limit of 1 NTU (Figure IV.1). With respect to the 95th percentile turbidity limit, roughly 46 percent of these systems are currently meeting the new requirement of 0.3 NTU (Figure IV.2) while approximately 70 percent meet this requirement 9 months out of the year. Estimates for systems needing to make changes to meet a turbidity performance limit of 0.3 NTU were based on the ability of systems currently to meet a 0.2 NTU. This assumption was intended to take into account a utility's concern with possible turbidity measurement error and to reflect the expectation that a number of utilities will attempt to achieve finished water turbidity levels below the regulatory performance level to assure compliance.

As depicted in Figure IV.1 and IV.2, the tighter turbidity performance standards for combined filter effluent in today's proposed rule reflect the actual, current performance many systems already achieve nationally. Revising the turbidity criteria effectively ensures that these systems continue to perform at their current level while also improving performance of a substantial number of systems that currently meet existing SWTR criteria, but operate at turbidity levels higher than proposed in today's rule.

BILLING CODE 6560-50-P EP10AP00.062

EP10AP00.063

Package Plants

During development of today's proposed rule, some stakeholders expressed concern regarding the ability of “package plants” to meet the proposed requirements. EPA evaluated these systems by gathering data from around the country. The information affirms the Agency's belief that package plants can and currently do meet the turbidity limits in today's proposed rule

EP10AP00.063

Package Plants

Package plants combine the processes of rapid mixing, flocculation, sedimentation and filtration (rapid sand, mixed or dual media filters) into a single package system. Package Filtration Plants are preconstructed, skid mounted and transported virtually assembled to the site. The use of tube settlers, plate settlers, or adsorption clarifiers in some Package Filtration Plants results in a compact size and more treatment capacity.

Package Filtration Plants are appropriate for treating water of a fairly consistent quality with low to moderate turbidity. Effective treatment of source waters containing high levels of or extreme variability in turbidity levels requires skilled operators and close operational attention. High turbidity or excessive color in the source water could require chemical dosages above the manufacturer's recommendations for the particular plant. Excessive turbidity levels may require presedimentation or a larger capacity plant. Specific design criteria of a typical package plant and operating and maintenance requirements can vary, but an example schematic is depicted in Figure IV.3.

EP10ap00.064

BILLING CODE 6560-50-C The Agency believes that historic data show that package plants have a comparable ability to meet turbidity requirements as conventional or direct filtration systems.

ackage plants have a comparable ability to meet turbidity requirements as conventional or direct filtration systems.

A 1987 report of pilot testing using a trailer-mounted package plant system to treat raw water from Clear Lake in Lakeport, California demonstrates the ability of such systems to achieve low turbidity requirements. The raw water contained moderate to high turbidity (18 to 103 NTU). Finished water turbidities ranged from 0.07 to 0.11 NTU (EPA, 1987). Two previous studies (USEPA, 1980a,b and Cambell et al., 1995) also illustrate the ability of package systems throughout the country to meet historic turbidity performance criteria. These studies are described briefly:

Package Water Treatment Plant Performance Evaluation (USEPA, 1980a,b)

The Agency conducted a study of package water treatment systems which encompassed 36 plants in Kentucky, West Virginia, and Tennessee. Results from that study showed that the plants could provide water that met the existing turbidity limits established under the National Interim Primary Drinking Water Standards. Of the 31 plants at which turbidity measurements were made, 23 (75 percent) were found to be meeting existing standards. Of the 8 which did not meet requirements, one did not use chemical coagulants, and 6 operated less than four hours per day. (USEPA, 1980a, b)

Package Plants for Small Systems: A Field Study (Cambell et al, 1995)

This 1992 project evaluated the application of package plant technology to small communities across the U.S. The project team visited 48 facilities across the U.S. Of the 29 surface water and GWUDI systems, 21 (72 percent) had grab turbidity samples less than 0.5 NTU, the 95 percent limit which became effective in June of 1993. Twelve systems (41 percent) had values less than today's proposed 0.3 NTU 95 percent turbidity limit. (Cambell et al., 1995) It should be noted that today's rule requires compliance with turbidity limits based on 4 hour measurments

S. Of the 29 surface water and GWUDI systems, 21 (72 percent) had grab turbidity samples less than 0.5 NTU, the 95 percent limit which became effective in June of 1993. Twelve systems (41 percent) had values less than today's proposed 0.3 NTU 95 percent turbidity limit. (Cambell et al., 1995) It should be noted that today's rule requires compliance with turbidity limits based on 4 hour measurments.

The Agency recently evaluated Filter Plant Performance Evaluations (FPPEs) conducted by the State of Pennsylvania, in an effort to quantify the comparative abilities of package plants and conventional filtration systems to meet the required turbidity limits. The data set consisted of 100 FPPEs conducted at systems serving populations fewer than 10,000 (PADEP, 1999). Thirty-seven FPPEs were conducted at traditional conventional filtration systems while 37 were conducted at package plants or “pre-engineered” systems. The remaining 26 systems utilized other filtration technologies.

The FPPEs provided a rating of either acceptable or unacceptable as determined by the evaluation team. This rating was based on an assessment of the capability of individual unit processes to continuously provide an effective barrier to the passage of microorganisms. Specific performance goals were utilized to evaluate the performance of the system including the consistent ability to produce a finished water turbidity of less than 0.1 NTU, which is lower than the combined filter effluent turbidity requirement in today's proposed rule. Seventy-three percent of the traditional conventional filtration systems were rated acceptable and 89 percent of the package plants were rated acceptable.

the traditional conventional filtration systems were rated acceptable and 89 percent of the package plants were rated acceptable.

The Agency also evaluated historic turbidity data graphs contained within each FPPE to provide a comparison of the ability of package plants and conventional systems to meet the 1 NTU max and 0.3 NTU 95 percent requirements that are contained in today's proposed rule. Sixty-seven percent of the conventional systems would meet today's proposed requirements while 74 percent of package systems in the data set would meet today's proposed requirements. The Agency believes that, when viewed alongside the aforementioned studies (USEPA, 1980a,b and Cambell et al., 1995), it is apparent that package systems have the ability to achieve more stringent turbidity limits.

Correlation Between CFE Requirements and 2-log Cryptosporidium Removal

Recent pilot scale experiments performed by the Agency assessed the ability of conventional treatment to control Cryptosporidium under steady state conditions. The work was performed with a pilot plant that was designed to minimize flow rates and as a result the number of oocyst required for continuous spiking. (Dugan et al. 1999)

Viable oocysts were fed into the plant influent at a concentration of 10 6 /L for 36 to 60 hours. The removals of oocysts and the surrogate parameters turbidity, total particle counts and aerobic endospores were measured through sedimentation and filtration. There was a positive correlation between the log removals of oocysts and all surrogate parameters through the coagulation and settling process. With proper coagulation control, the conventional treatment process achieved the 2 log total Cryptosporidium removal required by the IESWTR. In all cases where 2 log total removal was not achieved, the plant also did not comply with the IESWTR's CFE turbidity requirements. Table IV.6 provides information on Cryptosporidium removals from this study.

Table IV.6.—Log Removal of Oocysts (Dugan et al

With proper coagulation control, the conventional treatment process achieved the 2 log total Cryptosporidium removal required by the IESWTR. In all cases where 2 log total removal was not achieved, the plant also did not comply with the IESWTR's CFE turbidity requirements. Table IV.6 provides information on Cryptosporidium removals from this study.

Table IV.6.—Log Removal of Oocysts (Dugan et al. 1999) Run Log removal crypto Exceeds CFE requirements 1 4.5 No. 2 5.2 No. 3 1.6 Yes, average CFE 2.1 NTU. 4 1.7 Yes, only 88% CFE under 0.3 NTU. 5 4.1 No. 6 5.1 No. 7 0.2 Yes, average CFE 0.5 NTU. 8 0.5 Yes, only 83% CFE under 0.3 NTU. 9 5.1 No. 10 4.8 No. iii. Proposed Requirements

Today's proposed rule establishes combined filter effluent turbidity requirements which apply to all surface water and GWUDI systems which filter and serve populations fewer than 10,000. For conventional and direct filtration systems, the turbidity level of representative samples of a system's combined filter effluent water must be less than or equal to 0.3 NTU in at least 95 percent of the measurements taken each month. The turbidity level of representative samples of a system's filtered water must not exceed 1 NTU at any time.

For membrane filtration, (microfiltration, ultrafiltration, nanofiltration, and reverse osmosis) the Agency is proposing to require that the turbidity level of representative samples of a system's combined filter effluent water must be less than or equal to 0.3 NTU in at least 95 percent of the measurements taken each month. The turbidity level of representative samples of a system's filtered water must not exceed 1 NTU at any time. EPA included turbidity limits for membrane systems to allow such systems the ability to opt out of a possible costly demonstration of the ability to remove Cryptosporidium . The studies displayed previously in Table IV.4, demonstrate the ability of these technologies to achieve log-removals in excess of 2 log

of representative samples of a system's filtered water must not exceed 1 NTU at any time. EPA included turbidity limits for membrane systems to allow such systems the ability to opt out of a possible costly demonstration of the ability to remove Cryptosporidium . The studies displayed previously in Table IV.4, demonstrate the ability of these technologies to achieve log-removals in excess of 2 log. In lieu of these turbidity limits, a public water system which utilizes membrane filtration may demonstrate to the State for purposes of membrane approval (using pilot plant studies or other means) that membrane filtration in combination with disinfection treatment consistently achieves 3 log removal and/or inactivation of Giardia lamblia cysts, 4 log removal and/or inactivation of viruses, and 2 log removal of Cryptosporidium oocysts. For each approval, the State will set turbidity performance requirements that the system must meet at least 95 percent of the time and that the system may not exceed at any time at a level that consistently achieves 3 log removal and/or inactivation of Giardia lamblia cysts, 4 log removal and/or inactivation of viruses, and 2 log removal of Cryptosporidium oocysts.

Systems utilizing slow sand or diatomaceous earth filtration must continue to meet the combined filter effluent limits established for these technologies under the SWTR (found in § 141.73 (b) and (c)). Namely, the turbidity level of representative samples of a system's filtered water must be less than or equal to 1 NTU in at least 95 percent of the measurements taken each month and the turbidity level of representative samples of a system's filtered water must at no time exceed 5 NTU

ombined filter effluent limits established for these technologies under the SWTR (found in § 141.73 (b) and (c)). Namely, the turbidity level of representative samples of a system's filtered water must be less than or equal to 1 NTU in at least 95 percent of the measurements taken each month and the turbidity level of representative samples of a system's filtered water must at no time exceed 5 NTU.

For all other alternative filtration technologies (those other than conventional, direct, slow sand, diatomaceous earth, or membrane), public water systems must demonstrate to the State for purposes of approval (using pilot plant studies or other means), that the alternative filtration technology in combination with disinfection treatment, consistently achieves 3 log removal and/or inactivation of Giardia lamblia cysts, 4 log removal and/or inactivation of viruses, and 2 log removal of Cryptosporidium oocysts. For each approval, the State will set turbidity performance requirements that the system must meet at least 95 percent of the time and that the system may not exceed at any time at a level that consistently achieves 3 log removal and/or inactivatio

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