Consecutive System Guide
S^nS. Pro.«u0n for the Ground Water Rule
Office of Water (4607M) EPA 815-R-07-020 July 2007 www.epa.gov/safewater
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Purpose
The purpose of this guidance manual is solely to provide technical information for water
systems and states to assist them in complying with Ground Water Rule (GWR). The statutory
provisions and EPA regulations described in this document contain legally binding
requirements. This guidance is not a substitute for applicable legal requirements, nor is it a
regulation itself. Thus, it does not impose legally-binding requirements on any party, including
EPA, States, or the regulated community. While EPA has made every effort to ensure the
accuracy of the discussion in this guidance, the obligations of the regulated community are
determined by statutes, regulations, or other legally binding requirements. In the event of a
conflict between the discussion in this document and any statute or regulation, this document
would not be controlling.
Interested parties are free to raise questions and objections to the guidance and the
appropriateness of using it in a particular situation.
Although this manual describes suggestions for complying with GWR requirements, the
guidance presented here may not be appropriate for all situations, and alternative approaches
may provide satisfactory performance.
Authorship
This manual was prepared by EPA's Office of Water. Questions concerning this
document should be addressed to:
Michael Finn
U.S.EPA Office of Ground Water and Drinking Water
Standards and Risk Management Division
1200 Pennsylvania Ave, N.W. 4607M
Washington D.C. 20460-0001
fmn.michael@epa.gov
202-564-5261
202-564-3767(facsimile)
Acknowledgements
American Water Works Association
Association of Metropolitan Water Agencies
Association of State Drinking Water Administrators
Eugene Leung - California Department of Public Health
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CONTENTS
1. Introduction 1-1
1.1 General requirements of the GWR 1-1
2. GWR Requirements for Consecutive and Wholesale Ground Water Systems 2-1
2.1 Is triggered source water monitoring always required? 2-2
2.2 What if you believe a fecal indicator-positive source water sample is due to a lab error or other
cause rather than source water contamination? 2-2
2.3 What does the GWR require for a consecutive system that has a TC-positive routine sample
collected under TCRin its distribution system? 2-3
2.4 What does the GWR require for wholesale systems that are notified that its consecutive system
has a TC-positive routine sample collected under TCR in the consecutive system distribution
system? 2-3
2.5 What are the GWR triggered source water monitoring requirements for a consecutive system
with its own ground water sources? 2-3
2.6 What are the GWR triggered source water monitoring requirements for a consecutive system
with more than one connection to a wholesale system (or connections to more than one
wholesale system)? 2-5
2.7 What are the GWR triggered source water monitoring requirements for a wholesale system
with multiple wells? 2-6
2.8 What steps can a wholesale system take to facilitate meeting the requirements for triggered
source water monitoring under the GWR? 2-7
2.9 What steps can a consecutive system take to facilitate meeting the GWR notification
requirements for TC-positive samples collected under TCR? 2-8
2.10 What if a consecutive system is supplied with ground water by another consecutive system? 2-8
3. GWR Consecutive System Examples 3-1
3.1 Example 1 3-1
3.2 Example 2 3-3
3.3 Example 3 3-5
4. Example: Triggered Source Water Monitoring Plan 4-1
5. Glossary 5-1
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Abbreviations
GWR Ground Water Rule (40 CFR Part 141 Subpart S)
SDWA Safe Drinking Water Act
TCR Total Coliform Rule (40 CFR Part 141 Subpart C)
LCR Lead and Copper Rule (40 CFR Part 141 Subpart I)
TC Total Coliform
For more information, contact EPA's Safe Drinking Water Hotline, 1 (800) 426-4791, or see the
Office of Ground Water and Drinking Water web page at http://www.epa.gov/safewater.
This guidance manual is available electronically at
http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html. To order a paper copy of
guidance manuals, you may contact the US EPA Water Resource Center at 202-566 -1729 or by mail
at:
US Environmental Protection Agency
Water Resource Center (RC-4100)
1200 Pennsylvania Ave NW
Washington DC 20460
E-mail: center.water-resource@epa.gov
Other Guidance Manuals
EPA has developed other guidance manuals to aid EPA, State agencies, and you in
implementing the GWR and other rules and to help to ensure consistent implementation.
Consider the Source: A Pocket Guide to Protecting Your Source: Drinking Water Pocket
Guide #3 - An electronic version is available at http://www.epa.gov/safewater/sourcewater.
Public Notification Handbook (EPA 816- R- 00-010) - An electronic version is available at
http://www.epa.gov/safewater/publicnotification/compliancehelp.html.
Preparing Your Drinking Water Consumer Confidence Report (CCR), Revised Guidance
for Water Suppliers EPA 816-R-002, April 2005. This document provides information to
assist drinking water systems with preparing and distributing CCRs. An electronic version is
available at http://www.epa.gov/safewater/ccr/compliancehelp.html.
Consumer Confidence Report Rule: A Quick Reference Guide (EPA 816-F-02-026),
November 2002 - A condensed guide that provides a brief overview of the Consumer
Confidence Report Rule. An electronic version is available at
http://www.epa.gov/safewater/ccr/compliancehelp.html.
Surface Water Treatment Rule Guidance Manual - The Appendices also include CT tables
for the inactivation of Giardia and viruses for chlorine, chlorine dioxide and ozone.
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EPA is also developing a series of guidance documents to help public water systems implement
requirements associated with the GWR. Electronic versions of the guidance documents are, or will be,
available on the GWR Compliance Help page at
http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html.
Complying with the Ground Water Rule: Small Entity Compliance Guide (EPA 815-R-
07-018) - This guide is designed for owners and operators of public water systems serving
10,000 or fewer persons that are required to comply with the Ground Water Rule.
Ground Water Rule Corrective Action Guidance Manual - This manual provides
information for ground water systems that must provide corrective action as a result of
significant deficiencies or fecally-contaminated source water. The guidance includes technical
information on selecting appropriate disinfection technologies to enable primacy agencies and
PWSs to select the treatment most appropriate for a given system. It also provides technical
information to States and systems on eliminating sources of contamination, utilizing alternate
sources, and correcting significant deficiencies for situations in which disinfection is not the
selected corrective action.
Sanitary Survey Guidance Manual for Ground Water Systems - This guidance provides
information to assist States and other primacy programs in conducting sanitary surveys of
ground water systems.
Ground Water Rule Source Water Monitoring Methods Guidance Manual (EPA 815-R-
01-019) - This manual provides guidance on triggered and optional assessment source water
monitoring issues such as: selection of fecal indicators, sample collection and shipping, source
water monitoring methods, laboratory quality assurance (QA) and quality control (QC), and
evaluation of fecal indicator data. This manual also provides an overview of GWR
requirements and includes frequently asked questions regarding source water monitoring.
Ground Water Rule Source Assessment Guidance - This manual provides information on
procedures for identifying ground water sources at risk for contamination. Risk factors are
discussed with emphasis on identifying readily available factors suitable for office, rather than
field determination of risk at an individual PWS well. The guidance also lists sources of
information for making determinations and includes field methods for determining the presence
of a hydrogeologic barrier.
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1. Introduction
This guide describes the regulatory requirements of the Ground Water Rule (GWR) as it
applies to wholesale systems that supply ground water and to the consecutive water systems that
receive and distribute that ground water supply.
The GWR applies to all public water systems that use ground water unless the system combines
all of its ground water with surface water prior to treatment under 40 CFR 141 Subpart H
(Filtration and Disinfection).
A wholesale system is a public water system that supplies finished water to one or more other
public water systems.
A consecutive system is a public water system that buys or otherwise receives some or all of its
finished water from a wholesale system.
This document is intended to provide guidance to wholesale and consecutive ground water
systems and States in employing source water monitoring to identify fecal contamination of ground
water sources, one of the risk-based components of the GWR
Consecutive systems, and wholesale/consecutive system interactions and contractual
relationships, can be complex. There are a variety of State approaches to addressing regulatory
requirements for consecutive systems since most previous regulations under the SDWA did not
specifically address consecutive systems.
In the development of the GWR, the Stage 2 Disinfectants and Disinfection Byproducts Rule
and the Long Term 2 Enhanced Surface Water Treatment Rule under the SDWA, EPA has explicitly
addressed the applicability of these regulations to consecutive systems. EPA is providing guidance to
assist public water systems and States in implementing these regulations addressing consecutive
systems.
1.1 General requirements of the GWR
The requirements of the GWR (40 CFR Subpart S) constitute national primary drinking water
regulations. The GWR was published in the Federal Register on November 8, 2006 (71 Federal
Register 65574). A copy of the rule language can be found on EPA's website at
http: //www. epa. gov/safewater/di sinfecti on/gwr/regul ati on. html.
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The following are general GWR requirements applicable to wholesale and consecutive ground
water systems:
(a) Provide requested existing information to the State to aid the State in performing a
sanitary survey of your system.
(b) Correct any significant deficiencies identified by the State in your system within a
required timeframe.
(c) A consecutive system is required to report TC-positive routine sample collected under
TCR to the wholesale supplier(s) within 24 hours of being notified of the TC-positive
sample, unless the consecutive system or wholesale system(s) provide(s) 4-log (99.99
percent) treatment of viruses (by inactivation, removal or a combination of inactivation
or removal) for the wholesale ground water source(s).
(d) Wholesale systems and consecutive systems with their own ground water sources
must perform triggered microbial monitoring of ground water source(s) after a TC-
positive routine sample collected under TCR if they do not provide 4-log (99.99
percent) treatment of viruses (by inactivation, removal or a combination of inactivation
or removal) for the source.
(e) A wholesale system is required to notify the consecutive system(s) of a fecal indicator-
positive ground water source sample within 24 hours of being notified of the fecal
indicator-positive sample.
(f) Correct fecal contamination of your ground water source(s) within a required
timeframe.
(g) If required by your State, provide existing information to the State to aid the State in
performing a hydrogeologic sensitivity assessment for your source(s).
(h) Wholesale systems and consecutive systems with their own ground water sources
must perform assessment microbial monitoring of ground water source(s) if required
by the State.
(i) If required by the State, monitor any treatment process used to provide 4-log (99.99
percent) treatment of viruses (by inactivation, removal or a combination of inactivation
or removal) of viruses for your source(s), and
(j) Keep records and report to the State for certain requirements listed in (a)-(i) above.
The requirements specific to wholesale and consecutive systems are discussed in greater detail
in the next section.
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2. GWR Requirements for Consecutive and Wholesale Ground Water Systems
Exhibit 2.1 describes some of the specific responsibilities of consecutive and wholesale ground
water systems under the GWR.
Exhibit 2.1 GWR Requirements for Wholesale and Consecutive Systems
(Yes=Required, No=Not Required)
Ground Water Rule Requirement
Provide the State with information it requests to complete the
sanitary survey.
Correct any significant deficiencies identified by the State within
a required timeframe.
Notify your wholesale supplier within 24 hours of being notified
by your laboratory of a TC-positive routine sample collected
under TCR in your distribution system if you or your wholesale
supplier do not provide 4-log treatment of viruses for your
ground water supply.
Triggered1 source water monitoring of your own sources2 if you
do not provide 4-log treatment of viruses for those sources
Triggered1 source water monitoring of your source(s)2 if you are
notified of TC-positive routine sample collected under TCR by a
consecutive system you serve and if you or the consecutive
system do not provide a 4-log treatment of viruses for your
sources.
Notify consecutive systems you serve within 24 hours if a ground
water source sample is fecal indicator-positive.
Corrective action and/or treatment of your ground water sources,
if required, after a fecal indicator-positive source water sample.
If directed by the State, provide the State with information it
requests to complete the hydrogeologic sensitivity assessment for
your water system.
If directed by the State, conduct assessment source water
monitoring of your ground water sources.
Monitor treatment processes in accordance with GWR and State
requirements.
Reporting, record keeping and public notification requirements of
the GWR.
Wholesale
System
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Consecutive
System -100% of
supply
purchased
Yes
Yes
Yes
No
No
No
No
No
No
Yes
Yes
Consecutive system -
purchased and own
supply
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
1 Triggered source monitoring consists of collecting a sample from your ground water sources(s) after a TC-positive
routine sample collected under TCR and analyzing the sample for a fecal indicator approved by the State.
2 All sources do not have to be monitored under triggered monitoring if a "triggered source water monitoring plan" has
been developed and approved by the State.
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2.1 Is triggered source water monitoring always required?
A wholesale system or a consecutive system with its own ground water source(s) that has
evidence that the TC-positive routine sample collected under TCR is due to a distribution system
deficiency in the wholesale or consecutive
system distribution system, rather than
source water contamination, may apply to
the State for an exception to the triggered system Provides 4:'°9 treatment of
. . . °° viruses for a ground water source and
source water monitoring requirements on a
case-by-case basis.
If the wholesale system or consecutive
conducts compliance monitoring, triggered
source water monitoring for that source is
not required.
• The State is then required to make a
determination that the total coliform-
positive sample is caused by a distribution system deficiency in the wholesale or consecutive
distribution system.
• If the State decides to grant an exception to the triggered source water monitoring
requirements, then the State must document the decision in writing.
• You should have information that demonstrates the distribution problem that caused the
positive sample available for the State when you make your request for an exception.
The State may also establish criteria for distribution system conditions that will cause total
coliform-positive samples. If the total coliform-positive sample was collected in the wholesale or
consecutive distribution system under conditions that meet those State-specified criteria, you are not
required to conduct triggered source water monitoring. You must notify the State within 30 days of the
total coliform-positive sample that met State criteria for an exception to the triggered monitoring
requirements of the GWR. You should become familiar with your State's criteria for exceptions to
triggered monitoring.
2.2 What if you believe a fecal indicator-positive source water sample is due to a lab error or
other cause rather than source water contamination?
The State may invalidate a fecal indicator-positive source sample if the laboratory establishes
that improper sample analysis occurred or if the State has substantial grounds to believe that a sample
result is due to circumstances that do not reflect source water quality.
• If the State invalidates a fecal indicator-positive sample, then the GWR requires that the State
document the decision in writing.
• You should have information from the laboratory about the analysis or information that
demonstrates the fecal indicator-positive does not reflect source water quality available for the
State to review when you make your request to invalidate.
• If the State invalidates a fecal indicator-positive source water sample, the GWR requires that
the system must collect another source water sample and have it analyzed for the same fecal
indicator within 24 hours of being notified of the invalidation.
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2.3 What does the GWR require for a consecutive system that has a TC-positive routine
sample collected under TCR in its distribution system?
The GWR requires that a consecutive system that serves ground water from a wholesale system
that has not received 4-log treatment for viruses do the following after it is notified of a TC-positive
routine sample collected under TCR in the consecutive system's distribution system:
• Notify the wholesale system(s) of the TC-positive routine sample collected under TCR within
24 hours.
• Conduct public notification if a source water sample from a source that serves the consecutive
system is fecal indicator-positive.
2.4 What does the GWR require for wholesale systems that are notified that its consecutive
system has a TC-positive routine sample collected under TCR in the consecutive system
distribution system?
The GWR requires that a wholesale system that supplies ground water that has not received 4-
log treatment for viruses do the following when it is notified that its consecutive system has a TC-
positive routine sample collected under TCR in the consecutive system's distribution system:
• Collect a sample from the wholesale system's ground water source(s) and analyze the sample
for a fecal indicator;
• If a source water sample is fecal indicator-positive, notify all consecutive systems served by the
source (and conduct public notification if the source also serves the wholesale system's
consumers);
• Complete corrective action if required by the State after the initial fecal indicator-positive
sample; and
• Complete corrective action if any of the five additional samples collected after the initial fecal-
indicator positive is also fecal indicator-positive.
2.5 What are the GWR triggered source water monitoring requirements for a consecutive
system with its own ground water sources?
One of the main elements of the GWR is to identify contaminated ground water sources
through sampling and correct them as needed. If a consecutive system that has its own source(s) of
ground water has a TC-positive routine sample collected under TCR in its distribution system and does
not know which source is the cause, it must sample its source(s) and must notify its wholesale supplier
as required by the GWR.
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However, if the consecutive system can identify portions of its system that are served by only
one source, monitoring of all the sources may not be necessary. Consecutive systems with their own
sources should review their distribution system and available water quality data to determine if certain
parts of its system are served by a particular source. Information that could help identify areas served
by a particular source includes:
• Distribution system maps with pressure zones, isolation valves, storage tanks, sources, flow
meters, and any other significant facilities identified,
• Normally closed valves between service areas or pressure zones,
• Water quality information that identifies a particular source (alkalinity, pH, disinfectant
residual, fluoride, Lead and Copper Rule parameters etc.), and/or
• Distribution system models (proprietary software , EPANET). These tools need to be properly
calibrated and verified for valid results to be obtained in a specific distribution system.
If sufficient information is available, it may be possible to associate a routine TCR monitoring
site with a particular source. In the event of a TC-positive routine sample collected under TCR at such
a site, the system and the State can be confident that the correct source is being sampled.
A triggered source water monitoring plan can help ensure the correct source is sampled without
collecting unnecessary samples. Under the GWR, States may require a triggered source water
monitoring plan to be submitted for systems with more than one ground water source. Even if your
State does not require you to submit a triggered source water monitoring plan, you may wish to
develop one anyway and discuss it with your State. You may also want to develop a monitoring plan if
you rotate the wells you use on a regular basis or if you only use a well during certain times of the
year. For example, a triggered source water monitoring plan for a system with seasonal sources could
include both a summer and winter monitoring plan. The GWR requires that a triggered source water
sample be collected within 24 hours of being notified of a TC-positive routine sample collected under
TCR. A triggered source water monitoring plan can help you make a decision about where to collect a
sample more rapidly.
If directed by the State, systems must submit for State approval a triggered source
water monitoring plan that identifies one or more ground water sources that are
representative of each monitoring site in the system's sample siting plan under
141.21(a) (commonly known as the Total Coliform Rule) and that the system intends to
use to meet the triggered monitoring requirements of the Ground Water Rule
(§141.402).
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2.6 What are the GWR triggered source water monitoring requirements for a consecutive
system with more than one connection to a wholesale system (or connections to more than
one wholesale system)?
A consecutive system with multiple connections to a wholesale system or with connections to
more than one wholesale system may not know which connection is responsible for a TC-positive
routine sample collected under TCR in its distribution system. If the system does not know which
connection could be the cause and has more than one wholesale supplier, it must notify all its
wholesale suppliers as required by the GWR. However, if the consecutive system can identify portions
of its system that are served by a particular connection, monitoring of all the wholesale sources may
not be necessary.
Wholesale systems that serve through multiple connections should review their distribution
system and available water quality data to determine if certain consecutive systems or certain
connections are served by a particular source. As in the previous discussion, water quality data,
pressure zone and valve maps, and modeling can be useful in determining if a particular consecutive
system connection is served by particular source. This would also apply to wholesale systems that
serve consecutive systems served by more than one wholesale system. If there is sufficient information
to demonstrate that a particular sample location in a consecutive system is served by a particular
wholesale supply, then the required triggered source water monitoring may not have to be completed
for all sources.
For wholesale systems with multiple consecutive systems and consecutive systems with
multiple wholesale suppliers, the decision about where to collect a source water sample may not be
straightforward. As discussed previously, a triggered source water monitoring plan can help ensure the
correct source is sampled without collecting unnecessary samples. States may require a triggered
source water monitoring plan to be submitted for consecutive systems. Even if your State does not
require you to submit a triggered source water monitoring plan, you may wish to develop one and have
it reviewed by your State.
• A triggered source water monitoring plan is particularly useful for wholesale systems with
multiple consecutive systems and multiple sources and for consecutive systems with their own
sources, multiple wholesale suppliers, or multiple connections to a wholesale supplier.
• Wholesale and consecutive systems may also want to develop a triggered source water
monitoring plan if they rotate the wells used on a regular basis or only use a well during certain
times of the year.
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The GWR requires that each source in use be sampled within 24 hours of being
notified of a TC-positive routine sample collected under TCR. However, a State-
approved triggered source water monitoring plan can reduce the number of sources that
need to be sampled by identifying the specific source(s) serving the site of the TC-
positive routine sample collected under TCR.
With a triggered source water monitoring plan approved by the State, the system and the
State can have confidence that the correct source is being sampled after a TC-positive
routine sample collected under TCR without collecting a sample from every source in the
system. Part 4 of this guidance document describes the recommended minimum
elements of a triggered source water monitoring plan
2.7 What are the GWR triggered source water monitoring requirements for a wholesale
system with multiple wells?
Most wholesale ground water systems will have more than one well. The wells may not draw
from the same aquifer or certain wells may not serve certain parts of the system or customers. Once the
wholesale system is notified of a TC-positive routine sample collected under TCR by one of its
consecutive systems it must decide (within 24 hours) where to collect the required source water
samples and then collect the sample.
• If you are a wholesale system with more than one ground water source and you cannot identify
which wells serve the consecutive system, or identify a well or wells representative of the
ground water you supplied, you must sample all your sources.
• A representative well (or wells) should represent all your ground water sources that have the
potential to serve the area that had the total-coliform positive sample. Use of a representative
well (or wells) requires State approval.
• If a well (or wells) only serves some of the consecutive system(s) or portions of the wholesale
distribution system and you provide this information to the State in a triggered source water
monitoring plan, you may be able to sample only the source(s) that serves the system, or
portions of the system, with a TC-positive routine sample collected under TCR.
A triggered source water monitoring plan can help ensure that the source(s) that serve(s) the TCR
sample site is sampled without collecting samples from every source. States may require a triggered
source water monitoring plan to be submitted for systems with more than one ground water source.
The triggered source water monitoring plan can identify representative sources, or areas served by
different sources for likely distribution system scenarios, as well as sources used only seasonally or
on a rotating schedule so that the appropriate sources are sampled. Even if your State does not
require you to submit a triggered source water monitoring plan, you may wish to develop one anyway
and discuss it with your State. Part 4 of this guidance document describes the recommended
minimum elements of a triggered source water monitoring plan.
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2.8 What steps can a wholesale system take to facilitate meeting the requirements for
triggered source water monitoring under the GWR?
Under the GWR, a wholesale system is responsible for collecting a source water sample from
each source in use after being notified of a TC-positive routine sample collected under TCR in its own
or any of its consecutive systems' distribution system(s) unless it is has a State-approved triggered
source water monitoring plan that permits more focused source monitoring. Information about and
communication with the consecutive systems is needed to meet the GWR requirements
Steps a wholesale system can take to facilitate notification of TC-positive routine samples
collected under TCR in the consecutive systems it serves include:
• Identify all consecutive systems subject to TCR and to GWR triggered source water monitoring
under the GWR.
• Identify all connection(s) to those consecutive systems. Include information about the source
and status (active, standby, abandoned etc.) of each connection. Identify who has the ability to
alter the status of the connection and the date the status was last confirmed, if applicable.
• Identify those consecutive systems with their own ground water sources and those supplied by
another wholesale water system.
• Identify a contact (and alternates and after hours contacts) for each consecutive system, keep a
record of contact phone numbers, and develop a procedure to keep the contact list up to date
and accurate.
• Provide training and/or outreach materials on the requirements for notification by consecutive
systems to their wholesale suppliers and the need for timely notification to the wholesaler of
TC-positive routine samples collected under TCR in the consecutive system(s) distribution
system(s).
• Identify any consecutive systems that are non-community water systems. These systems may
not have full time staff and may have special needs for communication and training and
outreach. Timely notification of the wholesale system is an important element of the triggered
monitoring requirements of the GWR. The wholesale system may need to make special efforts
and arrangements for non-community consecutive systems.
• Identify the local laboratories used by the consecutive systems and contacts in those
laboratories. With cooperation of the consecutive systems and the laboratory, develop a
response plan for notification of any TC-positive routine samples collected under TCR from
either the wholesale system or the consecutive system.
• Identify staff contacts within the wholesale systems for consecutive system communication and
liaison functions.
• Develop a documentation process for all communications.
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2.9 What steps can a consecutive system take to facilitate meeting the GWR notification
requirements for TC-positive samples collected under TCR?
It is important to establish a communication process for the consecutive systems to notify the
wholesale system of TC-positive routine samples collected under TCR and be aware of water quality
and operational issues in the wholesale systems. Communication processes could include:
• Written communication and notification procedures. Non-community water systems without
full-time staff may need to make special arrangements to ensure timely notification from the
laboratory and timely notification of and communication with the wholesale system.
• Dedicated phone lines with after hours forwarding or recorded message capacity.
• Web-based information pages and message posting.
• Pager, cell phone, and wireless message transmission.
• E-mail notification.
• Laboratory notification of both the consecutive and wholesale system for a TC-positive routine
sample collected under TCR.
2.10 What if a consecutive system is supplied with ground water by another consecutive
system?
The GWR requires that a wholesale system collect and analyze at least one source water
sample if the wholesale system (or the consecutive system) does not provide 4-log virus treatment of
the ground water supplied to the consecutive system and a TC-positive routine sample collected under
TCR occurs in the consecutive system.
In some systems, the wholesale supply may pass through one or more consecutive systems
before reaching its final consecutive connection. In these cases, a triggered source water monitoring
plan and reliable communications and notification processes are important to ensure that both the
consecutive system and the wholesale system meet their responsibilities under the GWR. Triggered
source water monitoring plans can be prepared for the combined wholesale/consecutive distribution
system or on a system-by-system basis.
Source water monitoring plans for wholesale systems should identify the consecutive systems
served and, if applicable, the sources serving each consecutive system. Source water monitoring plans
for consecutive systems should identify the wholesale supply or suppliers for the points of entry.
Source water monitoring plans for combined wholesale/consecutive should include all the information
describe previously for individual wholesale or consecutive systems. Sections 2.8 and 2.9 describe
important elements of communication and notification between wholesale and consecutive systems.
Part 4 of this guidance document describes the recommended minimum elements of a triggered source
water monitoring plan.
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3. GWR Consecutive System Examples
3.1 Example 1
Figure 3.1 - First Valley Water District System
S-1
. . r -^ tv-/l
Key
S-1
P-1
W-1
P-2
T-1
T-2
T-3
T-4
T-5
T-6
Source #1- Purchase
Pump Station #1-W:
(operational only if tf
Well #1- Alder Grov
TCR Sampling Site #
TCR Sampling Site #
TCR Sampling Site #
TCR Sampling Site #
TCR Sampling Site #
TCR Sampling Site #
W-1
d Water from Big Mountain Water Dist.
alnut Grove Pump Station
^-1 is out of service)
2 Well
der Grove Well Pump Station
1
2
3
4
5
6
["•"-I ( '
/\ P-2\
/P-
1 \
A A A A A A
A A A A A A
Low Zone
A A A A A A
nnnnnN
T-3 \ I I I | \
Mixed Zone
000100
I f 1 f f1"^
High Zone
- The First Valley Water District purchases ground water from the Big Mountain Water District
in addition to having one well.
- The First Valley supply is delivered through valved connections from Big Mountain's Cross
County Pipeline.
- First Valley Water District also has its own well that is used routinely.
- Pressure in the Big Mountain supply is only adequate to serve the low zone of the system.
- Some mixing of the Big Mountain supply and First Valley's own supply occurs between the
low and the high zone (Mixed Zone).
- The Big Mountain supply can only reach the high zone when the Walnut Grove Pump Station
is operated to move water between zones and this occurs only when the Alder Grove Well is
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out of service or in an emergency (fire, major leak).
Based on the hydraulics of the First Valley system:
- A TC-positive routine sample collected under TCR in the low zone (TCR sites 1 and 2) triggers
source water sampling in the Big Mountain Water District's sources.
- A TC-positive routine sample collected under TCR in the high zone (TCR sites 5 and 6)
triggers a source water sample from the Alder Grove Well. This is true as long as the Walnut
Grove Pump Station was not operating at the time of the TC-positive routine sample collected
under TCR.
- The mixed zone contains water from both sources. Since a single source cannot be identified
for this zone, triggered source water samples must be collected from both the Big Mountain
source(s) and the Alder Grove Well after a TC-positive routine sample collected under TCR in
the mixed zone (TCR sites 3 and 4).
In this example, system hydraulics and operation allow for some of the routine TCR monitoring
sites to be identified as supplied by only one of the First Valley District's sources. The GWR requires
that source water samples be collected no more than 24 hours after being notified of a TC-positive
routine sample collected under TCR, or for a wholesale system, no more than 24 hours after being
notified by their consecutive system of TC-positive routine sample collected under TCR in the
consecutive system's distribution system. To meet these requirements, it important that samples be
properly identified and that system personnel are aware of the correct response to a TC-positive routine
sample collected under TCR at a particular sample location. Also, the State would have to approve
representative sampling or a triggered source water monitoring plan.
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3.2 Example 2
Figure 3.2 - Second Valley Water District System
S-1
Kev
S-1 Source #1 - Purchased Water from Big Mesa Water District
S-2 Source #2 - Purchased Water from Third Valley Water District
P-1 Pump Station (normally isolated)
Pressure Zone 1
Pressure Zone 2
S-2
»NXI-
AA
Pressure Zone 3
Note: Figures not drawn to scale
The Second Valley Water District purchases its entire supply from the Big Mesa Water District
and the Third Valley Water District.
- Second Valley has three pressure zones in its system.
- Two zones are served by connection to Big Mesa; the third zone is served by a connection to a
Third Valley Water District pipeline.
- The Big Mesa Water District adds chlorine to its ground water supply but does not provide a 4-
log inactivation of viruses.
- The Third Valley Water District adds chloramine to its supply.
- The Third Valley supply is a mix of surface water and ground water depending on the time of
year and Third Valley provides a 4-log virus inactivation for its ground water supply.
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- The three zones are interconnected but the Second Valley operators keeps the connections
between the zones at valves and pump stations closed to prevent mixing and the taste and odor
complaints that often happen when the two supplies mix.
In this example, there are multiple wholesale sources, however the two sources do not mix
under normal conditions. If a TC-positive routine sample collected under TCR occurred in the Second
Valley system:
- A source water sample from the Big Mesa sources would be required for a TC-positive routine
sample collected under TCR in the two zones served by the Big Mesa supply.
- No source water sample would be required for TC-positive routine sample collected under TCR
that occurred in the zone served by the Third Valley supply since Third Valley provides a 4-log
virus inactivation for its sources.
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3.3 Example 3
Figure 3.3 - Fourth Valley Water District System
S-1
••MXl-
Pressure Zone 1
X
S-2
000000
TTTTTT
Key
S-1
S-2
Source #1 - Purchased Water from Big Gulch Water District
Source #2 - Purchased Water from Last Valley Water District
Pressure Zone 2
oooo
A A
Pressure Zone 3
Note: Figures not drawn to scale
The Fourth Valley Water District purchases its entire supply from the Big Gulch Water District
and the Last Valley Water District. Fourth Valley has three pressure zones in its system. One zone is
served by the connection to Big Gulch the other two zones are served by connections to the Last
Valley Water District transmission pipeline.
- The Big Gulch Water District adds chlorine to its wholesale ground water supply but does not
provide a 4-log inactivation of viruses.
- The Last Valley Water District supply is a mix of surface water and ground water.
- The Last Valley Water District also adds chlorine to its supply but does not provide a 4-log
inactivation of viruses for its ground water sources.
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- The Last Valley Water District surface water supply has a low alkalinity and the Last Valley
District adjusts the pH to protect its pipelines and meet the water quality parameters set by the
State under the Lead and Copper Rule.
- As Fourth Valley has conducted its Lead and Copper Rule water quality parameters tap
sampling it has identified the parts of its service area that receive the Last Valley supply. That
information has been put on a distribution system map along with the locations of the routine
TCR monitoring sites.
This example is more complicated than the first two because Fourth Valley has two wholesale
supplies with both surface and ground water sources and multiple pressure zones. For large wholesale
systems with multiple customers and multiple sources, deciding where to collect the required source
water samples could be even more complicated.
In this example, Fourth Valley has information it collected for the Lead and Copper Rule that
could allow it to identify the wholesale supply at any of its routine TCR monitoring sites and reduce
the number of source water samples that must be collected. The water quality information combined
with a triggered source water monitoring plan would allow the Fourth Valley system to quickly
identify the source and notify the correct wholesale supplier.
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4. Example: Triggered Source Water Monitoring Plan
A triggered source water monitoring plan can help ensure that the source(s) that serve the TCR
sample site is sampled without collecting samples from every source. States may require a triggered
source water monitoring plan to be submitted for systems with more than one ground water source.
The triggered source water monitoring plan can identify representative sources, or areas served by
different sources for likely distribution system scenarios, as well as sources used only seasonally or on
a rotating schedule so that the appropriate sources are sampled. For example, a triggered source water
monitoring plan for a system with seasonal sources could include both a summer and a winter
monitoring plan. Even if your State does not require you to submit a triggered source water monitoring
plan, you may wish to develop one anyway and discuss it with your State.
A triggered source water monitoring plan is particularly useful for wholesale systems with
multiple consecutive systems and multiple sources and for consecutive systems with their own
sources, multiple wholesale suppliers, or multiple connections to a wholesale supplier. A triggered
source water monitoring plan should include the following minimum elements:
1) Map or schematic of the system with sources and/or points of entry and TCR compliance
monitoring locations identified. Your distribution system map or schematic should not
contain information that poses a security risk to your system. EPA recommends that you
submit either a distribution system schematic with no landmarks or addresses or a City map
without locations of pipes indicated.
2) Identify the source type for each source/point of entry (e.g., seasonal, emergency, ground
water, surface water etc.).
3) Identify the source(s) serving each TCR compliance monitoring location and the basis for the
determination (e.g., system hydraulics, operation, water quality data, etc.).
4) For wholesale systems, the consecutive systems served and, if applicable, the sources serving
each consecutive system.
5) For consecutive systems, the wholesale supply or suppliers for the points of entry.
6) Identify any representative ground water source(s) that will be used to satisfy the triggered
monitoring requirements of the GWR and the basis for the selection (e.g.
geologic/hydrogeologic information, well construction data, water quality data, sanitary
surveys, Source Water Assessments, etc.).
7) Any changes or variations expected in the monitoring plan (e.g., use of seasonal sources,
rotating sources, etc.).
Exhibit 4-1 is an example triggered source water monitoring plan. The plan is for the First
Valley Water system described in Section 3.1 and illustrated in Figure 3.1.
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Exhibit 4.1 Triggered Source Water Monitoring Plan - First Valley Water System
(See Section 3.1 and Figure 3-1)
Routine TCR site
#1 Turnout Valve lot
#2 Redwood Park
#3 Old Town
# 4 Walnut Grove
PS
# 5 Freshwater
School
# 6 Corporation
Yard
Served by
Big Mountain
Big Mountain
Both
Both
Alder Grove Well
Alder Grove Well
Source sample at/by
Big Mountain WD
Big Mountain WD
Big Mountain WD
First Valley WD
(Alder Grove Well
sample tap)
Big Mountain WD
First Valley WD
(Alder Grove Well
sample tap)
First Valley WD
(Alder Grove Well
sample tap)
First Valley (Alder
Grove Well sample
tap)
Comments/Instructions
Contact Big Mountain
WD Water Quality
Section
Day phone:
Fax:
After hours:
Contact Big Mountain
WD Water Quality
Section.
Contact lab for sample
pick up.
Day phone:
Fax:
After hours :
Sample bottles at corp
yard -label as SOURCE
and follow chain of
custody
Contact lab for sample
pick up.
Sample bottles at corp
yard -label as SOURCE
and follow chain of
custody
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5. Glossary
Consecutive system - A public water system that buys or otherwise receives some or all of its finished
water from a wholesale system.
Fecal Indicator - Microorganisms (i.e., bacteria and viruses) that are closely associated with fecal
contamination and indicate that a source of water may be fecally-contaminated. For the GWR, fecal
indicators areE.Coli, enterococci, or coliphage, as specified by the State.
Sanitary survey - A "sanitary survey", as conducted by the State, includes, but is not limited to, an
onsite review of the water source (identifying sources of contamination by using results of source
water assessments or other relevant information, where available), facilities, equipment, operation,
maintenance, and monitoring compliance of a public water system to evaluate the adequacy of the
system, its sources and operations and the distribution of safe drinking water.
Significant deficiency - A "significant deficiency" includes, but is not limited to, a defect in design,
operation, or maintenance, or a failure or malfunction of the sources, treatment, storage, or distribution
system that the State determines to be causing, or has the potential for causing, the introduction of
contamination into the water delivered to consumers.
State - Refers to the agency of the State or Tribal government which has jurisdiction over public water
systems. During any period when a State or Tribal government does not have primary enforcement
responsibility pursuant to Section 1413 of the Safe Drinking Water Act, the term 'State' means the
Regional Administrator of the U.S. Environmental Protection Agency.
Source sample - A sample collected at the source of water for the public water system before
treatment or, if no treatment is provided, before the distribution system (i.e., at the wellhead)
Subpart H system - A public water system serving surface water or ground water under the influence
of surface water. These systems are subject to the filtration and disinfection requirements of 40 CFR
Subpart H.
Total Coliforms - A group of closely related bacteria that are generally harmless. They are natural
and common inhabitants of the soil and ambient waters (such as lakes and rivers).
Treatment technique violation - Violation of a treatment technique established in lieu of a Maximum
Contaminant Level. For the GWR, this includes failure to provide corrective action for fecal
contamination of ground water source and failure to correct significant deficiencies. Treatment
technique violations require the system to provide public notification and systems in violation of
treatment technique requirements are subject to enforcement actions by the State and EPA.
Triggered Monitoring - For the GWR, ground water source samples collected after a routine TC-
positive routine sample collected under TCR and analyzed for a fecal indicator. Triggered monitoring
consists of collection of source water samples and analysis of those samples for a fecal indicator
specified by the State. For systems collecting one routine TCR sample or fewer each month, one of the
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four repeat samples required under the TCR may be collected from the ground water source to satisfy
the triggered ground water source monitoring requirements of the GWR. The GWR is not applicable to
any source determined by the State to be ground water under the direct influence of surface water
(GWUDI).
Well- For the purposes of the GWR, the term "well" includes springs, spring boxes, vertical and
horizontal wells, infiltration galleries and any other method of delivering ground water.
Wholesale system - A wholesale system is a public water system that treats source water as necessary
to produce finished water and then delivers some or all of that finished water to another public water
system. Delivery may be through a direct connection or through the distribution system.
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