£ fm \ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
| WASHINGTON, D.C. 20460
FEB 2 2012
OFFICE OF
WATER
MEMORANDUM
SUBJECT: Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules (DBPRs) •
100% Purchasing Consecutive System TTHM and HAAS Reduced Monitoring
Qualifications Clarification
.1
FROM: Mindy Eisenberg, Acting Chief *
r
Protection Branch O
Drinking Water Protection Division
TO: Regional Drinking Water Managers
Regions I-X
This memorandum is in response to multiple requests for EPA Headquarters to clarify its
position regarding 100% purchasing consecutive systems qualifying for reduced total
trihalomethanes (TTHM) and five haloacetic acids (HAAS) monitoring.
The requirements for subpart H systems to qualify for reduced monitoring under the Stage 1
DBPR, including a source water total organic carbon (TOC) < 4.0 mg/L as running annual
average (RAA), are detailed in 40 C.F.R. § 141.132(b)(l)(ii). The TOC RAA is based on
monitoring conducted under 40 C.F.R. §141.132(d) for systems using conventional filtration
treatment or 40 C.F.R. §141.132(b)(l)(iii) for systems that use other filtration technologies or
unfiltered systems. While these sections do not explicitly refer to consecutive systems, a
consecutive system meets the definition of a subpart H system if it uses water that is from a
surface water or ground water under the influence of surface water source, including finished
water from a wholesale system. Therefore, any consecutive system that uses surface water or
ground water under the influence of surface water is subject to the provision to demonstrate a
source water TOC running annual average (RAA) less than or equal to 4.0 mg/L on a continuing
basis to qualify or remain on reduced monitoring.
TOC can influence the formation of disinfectant and disinfection byproducts (DBFs) in the water
with the addition of a disinfectant. The removal of TOC is used as a performance indicator for
DBF precursor control. The use of source water TOC data allows for a primacy agency to make
an informed decision regarding reduced TTHM and HAA5 monitoring for a subpart H system.
Source water TOC samples must be collected every 30 days at a location prior to any treatment
for this requirement. 40 C.F.R. §141.132(b)(l)(ii & iii). Once qualified for reduced monitoring
Internet Address (URL) • http://www.epa.gov
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for TTHM and HAA5, a system may reduce source water TOC monitoring to quarterly TOC
samples taken every 90 days at a location prior to any treatment. 40 C.F.R. §141.132(b)(l)(iii).
For reduced TTHM and HAAS monitoring, there are two types of consecutive systems to
consider. The first would be a consecutive system served by a wholesaler using conventional
filtration treatment. This type of consecutive system may qualify for reduced monitoring based
on the wholesaler's TOC data collected under 40 C.F.R. §141.132(d) and the consecutive
system's own DBF levels (i.e., TTHM < 0.040 mg/L and HAAS RAA < 0.030 mg/L). A
consecutive system with documented DBF data that qualifies for reduced monitoring, along with
the wholesaler's qualifying TOC data, could be considered by the primacy agency in making a
determination to approve reduced monitoring for the consecutive system. A state may have
source water TOC data available to review and/or the consecutive system may need to contact
the wholesaler to obtain data demonstrating that it can qualify for reduced monitoring.
The second type of consecutive system served by a wholesaler using treatment other than
conventional filtration treatment may still qualify for reduced monitoring, but source water TOC
monitoring is required. Such wholesalers are not required to collect source water TOC data as
described in 40 C.F.R. § 141.135. However, in order to qualify for reduced DBF monitoring,
source water TOC data is required. 40 CFR §141.132(b)(l)(iii). A consecutive system seeking
approval for reduced DBF monitoring but not specifically required to monitor for source water
TOC under subpart L would have to arrange for source water TOC data to be collected. In
addition to qualifying TOC data, the consecutive system will have to meet the TTHM and HAAS
requirements for reduced monitoring. 40 C.F.R. § 141.132(b)(l)(ii). Collection of the source
water TOC data will require the consecutive system to coordinate with its wholesaler to obtain
this information.
These requirements are also continued in the Stage 2 DBPR at 40 C.F.R. §141.623. Systems may
only use data collected under the provisions of subpart L (if there are no changes to monitoring
locations, as specified in 40 C.F.R. §141.627) or subpart V to qualify for reduced monitoring. 40
C.F.R. §141.623(a). A consecutive system using new TTHM/HAA5 monitoring locations under
Stage 2 (compared to Stage 1) cannot begin reduced compliance monitoring under Stage 2 until
the consecutive system has adequate data. 40 C.F.R. § 141.623(a). Note that consecutive
systems will have to continue meeting the monitoring and reporting requirements to remain on
reduced monitoring. 40 C.F.R. §141.623(b). The primacy agency, which is the state in most
cases, is responsible for the implementation of these requirements and has oversight of the
wholesaler and the consecutive system. The state will likely have a wealth of information
available when making a determination whether to approve reduced TTHM and HAAS
monitoring. The reduced monitoring decision must include a determination that the monitoring
results for TTHM, HAAS, and source water TOC level meet the criteria for reduced monitoring,
and may not be based solely on TTHM/HAA5 levels. Also, a state may return a system to
routine monitoring at its discretion. 40 C.F.R. §141.623(d).
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In conclusion, a 100% purchasing consecutive systems using surface water or ground water
under the direct influence of surface water meets the definition of a subpart H system. The
qualifying requirements for reduced TTHM and HAAS monitoring for subpart H systems are
detailed in 40 C.F.R. §141.132(5X1)00,
Cc: Jim Taft, ASDWA
MDBP Implementation Workgroup
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