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Transition
from Stage 1 to Stage 2
Disinfection Byproducts Rule Monitoring
DOH PUB.#331-377 (09/07)
The Stage 2 Disinfectants and Disinfection
Byproducts Rule (Stage 2 DBPR) published in January 2006, sets new
monitoring requirements for total trihalomethanes (TTHM) and haloacetic
acids (HAA5). It applies to community and non-transient non-community (NTNC)
water systems that use chlorine, chloramines, chlorine dioxide or ozone
in their treatment process.
Stage 2 DBPR requirements are in effect
The U.S. Environmental Protection Agency
(EPA) will enforce Stage 2 DBPR requirements until the Office of
Drinking Water (ODW) adopts them into our drinking water rules. System
size determines when systems must comply with Stage 2 DBPR requirements.
Until 2014, some systems must meet Stage 1 and Stage 2 DBPR monitoring
requirements. After 2014, all systems must meet Stage 2 DBPR monitoring
requirements for TTHM and HAA5.
|
Stage 2 DBPR
Implementation Deadlines |
|
Public water system population¹ |
Submit IDSE
document2 or receive a 40/30 Certification or Very
Small System Waiver |
Complete IDSE
monitoring or study |
Submit IDSE
Report |
Begin routine
monitoring according to Stage 2 Rule |
|
Due Dates |
| ≥100,000 |
Oct. 1, 2006 |
Sept. 30, 2008 |
Jan. 1, 2009 |
April 1, 2012 |
| 50K – 99,999 |
April 1, 2007 |
March 31, 2009 |
July 1, 2009 |
Oct. 1, 2012 |
| 10K – 49,999 |
Oct. 1, 2007 |
Sept. 30, 2009 |
Jan. 1, 2010 |
Oct. 1, 2013 |
| < 10,000 |
April 1, 2008 |
March 31, 2010 |
July 1, 2010 |
Oct. 1, 20133
Oct. 1, 20144 |
- Public water systems that have non-emergency interties
with other systems must comply with the deadlines for the
largest system in their combined distribution system.
- An Initial Distribution System Evaluation (IDSE)
document is a standard monitoring plan or system-specific
study plan. NTNC systems serving <10,000 people are exempt.
- Surface water systems that did not have to do
Cryptosporidium monitoring under the Long Term 2 Enhanced
Surface Water Treatment Rule (LT2ESWTR) and ground water
systems.
- Surface water systems that also did Cryptosporidium
monitoring under LT2ESWTR.
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Monitoring for bromate, chlorite and
disinfectant residuals will continue as required by Stage 1 DBPR.
Systems using ozone may qualify for reduced bromate monitoring if they
use a laboratory certified to analyze bromate using one of the new
EPA-approved methods.
Determining high TTHM and HAA5 locations
Under Stage 2, systems will monitor at
locations with the highest averages of TTHM and HAA5. To determine these
locations, Stage 2 DBPR will require many systems to complete an Initial
Distribution System Evaluation (IDSE). Systems may use a Standard
Monitoring Plan or a System-Specific Study. These options usually
involve sampling TTHM and HAA5 at locations other than those used to
comply with Stage 1 DBPR. These samples are in addition to Stage 1 DBPR
samples and do not count for Stage 1 compliance.
Systems not required to do an Initial
Distribution System Evaluation will use Stage 1 DBPR monitoring results
to determine routine Stage 2 DBPR monitoring locations. These systems
include:
.
Community systems serving fewer than 500
people that have a Very Small System Waiver (VSSW) *. To qualify, you
must have TTHM and HAA5 sample results taken at correct locations.
Samples taken from the source after treatment are not acceptable. You
must take samples at locations representing the maximum residence time
in the distribution system and during the month of warmest water
temperature. Many water systems already have a VSSW.
Systems qualifying for a 40/30 Certification
Waiver .* To qualify, (1) you cannot have any Stage 1 DBPR TTHM or
HAA5 monitoring violations AND (2) every sample taken during a
prescribed eight-consecutive-quarter period must be no more than 40
μg/L
(micrograms per liter) for TTHM and 30
μg/L
for
HAA5. (This does not mean you are required to conduct quarterly
monitoring.) Systems must submit directly to EPA a 40/30 certification
letter, a map showing entry points and TTHM and HAA5 monitoring
locations, and the TTHM and HAA5 data the certification is based on.
*EPA will issue written waivers to
qualifying systems.
Comparing Stage 1 and Stage 2 DBPR
requirements for TTHM and HAA5
|
Element |
Stage 1 DBPR |
Stage 2 DBPR |
| Consecutive systems1 |
Must monitor only if they
themselves use any type of chlorination or ozone treatment. Not
required to monitor if only the supplier uses it. |
Must monitor if any water they
provide is treated with any type of chlorination or ozone, even
if only the supplier uses it. |
| Number of samples |
Related to population served,
source type, and number of treatment plants used. |
Only related to population
served and source type. Number of treatment plants used does not
matter. |
| Sample locations |
At locations representing the maximum residence
time2 in the distribution system. Larger
systems may include locations of average residence time. |
Locations of highest TTHM and
HAA5 averages based on both:
- Interim Stage 2 DBPR monitoring during Initial
Distribution System Evaluation, if required.
- Stage 1 DBPR monitoring.
Locations of highest TTHM and HAA5 averages may or may not be
the same. Larger systems must include some Stage 1 DBPR
locations. |
| Determining maximum
contaminant level compliance |
Based on the running annual
average. This is the average of four consecutive quarters of
all samples taken in the distribution system for TTHM and HAA5. |
Based on the locational
running annual average. This is the average of four
consecutive quarters of samples taken at each specific sampling
location within the distribution system for TTHM and HAA5. |
| Compliance dates |
Meet deadlines according to
direct service population and source type. |
Meet deadlines for the largest
system within the combined distribution system3. |
- Consecutive systems = systems that receive water from other
public water systems through non-emergency interties.
- Residence time = time water is in the distribution system
between the chemical application point and when consumers use it.
- Combined distribution system = all wholesale water suppliers and
consecutive systems connected through non-emergency interties.
For more information
Stage 2 DBPR requirements: C all
EPA at (206) 553-1890 or get
Complying with the Stage 2 Disinfectants
and Disinfection Byproducts Rule: Small Entity Compliance Guide on EPA's
Web Site.
Stage 1 DBPR requirements: Call the
Office of Drinking Water:
Northwest Region (253) 395-6762
Southwest Region (360) 236-3035
Eastern Region (509) 456-2774
DBP Program Coordinator (253) 395-6770
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