The following definitions shall apply in the interpretation
and enforcement of this subchapter. If a word or term used in this
subchapter is not contained in the following list, its definition
shall be as shown in §290.38 of this title (relating to Definitions)
or in 40 Code of Federal Regulations (CFR) §141.2. Other technical
terms used shall have the meanings or definitions listed in the latest
edition of "Glossary, Water and Wastewater Control Engineering," prepared
by a joint editorial board representing the American Public Health
Association, American Society of Civil Engineers, American Water Works
Association, and the Water Pollution Control Federation.
(1) Assessment source monitoring--Raw groundwater source
monitoring required by the executive director based on groundwater
source susceptibility to fecal contaminants.
(2) Combined distribution system (CDS)--The interconnected
distribution system consisting of the distribution systems of wholesale
systems and of the consecutive systems that receive finished water.
(A) The executive director may determine that the CDS
does not include certain systems based on factors such as providing
or receiving a relatively small amount of water or only on an emergency
basis.
(B) A public water system may be determined to be in
a different CDS for the purposes of compliance with regulations based
on the Stage 2 Disinfection Byproducts Rule (DBP2) and the Long Term
Stage 2 Enhanced Surface Water Treatment Rule (LT2).
(i) For the purposes of raw water monitoring under
LT2, the CDS shall be based on the retail and wholesale population
served by each surface water treatment plant or plant treating groundwater
under the direct influence of surface water.
(ii) For the purposes of DBP2, the CDS shall be determined
based on the retail population served within each individual system's
distribution system.
(3) Compliance cycle--The nine-year (calendar year)
cycle during which public water systems must monitor. Each compliance
cycle consists of three, three-year compliance periods.
(4) Compliance period--A three-year (calendar year)
period within a compliance cycle. Each compliance cycle has three,
three-year compliance periods. Within the first compliance cycle,
the first compliance period is called the initial compliance period.
(5) Comprehensive performance evaluation (CPE)--A thorough
review and analysis of a treatment plant's performance-based capabilities
and the associated administrative, operation and maintenance practices.
It is conducted to identify factors that may be adversely impacting
a plant's capability to achieve compliance and to emphasize approaches
that can be implemented without significant capital improvements.
The comprehensive performance evaluation consists of the following
components: assessment of plant performance; evaluation of major unit
processes; identification and prioritization of performance limiting
factors; assessment of the applicability of comprehensive technical
assistance; and preparation of a CPE report.
(6) Consecutive system--A public water system that
receives some or all of its raw water or finished water from one or
more other public water systems.
(7) Disinfection profile--A summary of daily Cryptosporidium, Giardia lamblia, and viral
inactivation obtained through disinfection at the treatment plant.
(8) Disinfection by-products (DBP)--Chemical compounds
formed by the reaction of a disinfectant with the natural organic
matter present in water.
(9) Domestic or other non-distribution system plumbing
problem--A coliform contamination problem in a public water system
with more than one service connection that is limited to the specific
service connection from which the coliform-positive sample was taken.
(10) DPD--Abbreviation for N,N-diethyl-p-phenylenediamine,
a reagent used in the determination of several residuals. DPD methods
are available for both volumetric (titration) and colorimetric determinations,
and are commonly used in the field as part of a colorimetric test
kit.
(11) Dual sample set--A set of two samples collected
at the same time and same location, with one sample analyzed for total
trihalomethanes (TTHM) and the other sample analyzed for haloacetic
acids-group of five (HAA5). Dual sample sets are collected for the
purposes of conducting an initial distribution system evaluation and
determining compliance with the TTHM and HAA5 maximum contaminant
levels.
(12) Enhanced coagulation--The removal of disinfection
by-product precursors to a specified level by conventional coagulation
and sedimentation.
(13) Enhanced softening--The removal of disinfection
by-product precursors to a specified level by softening.
(14) Entry point--Any point where a source of treated
water first enters the distribution system. Entry points to the distribution
system may include points where chlorinated well water, treated surface
water, rechlorinated water from storage, or water purchased from another
supplier enters the distribution system.
(15) Entry point sampling site--A sampling site representing
the quality of the water entering the distribution system at each
designated entry point.
(16) Fecal indicators--Microbiological organisms used
to indicate the presence of fecal contamination. Examples include;
fecal coliform, Escherichia coli (E. coli), enterococci,
and coliphage.
(17) Filter assessment--An in-depth evaluation of an
individual filter, including the analysis of historical filtered water
turbidity from the filter, development of a filter profile, evaluation
of media condition, identification and prioritization of factors limiting
filter performance, appraisal of the applicability of corrections,
and preparation of a filter self-assessment report.
(18) Filter profile--A graphical representation of
individual filter performance, based on continuous turbidity measurements
or total particle counts versus time for an entire filter run. The
filter profile must include all the data collected from the time that
the filter placed into service until the time that the backwash cycle
is complete and the filter is restarted. The filter profile must also
include data collected as another filter is being backwashed.
(19) Finished water--Water that is introduced into
the distribution system of a public water system and intended for
distribution and consumption without further treatment, except as
necessary to maintain water quality within the distribution system
(e.g., booster disinfection, addition of corrosion control chemicals).
(20) Groundwater corrective action--Action required
when a raw groundwater source sample is found to be positive for Escherichia coli (E. coli) or other fecal
indicators as described under §290.116(b) of this title (relating
to Groundwater Corrective Actions and Treatment Techniques).
(21) Groundwater corrective action plan--A plan approved
by the executive director documenting the steps to be taken to address
fecal contamination of a groundwater source as described under §290.116(b)
of this title (relating to Groundwater Corrective Actions and Treatment
Techniques). The groundwater corrective action plan must be approved
within 30 days of being notified of the fecal contamination.
(22) Groundwater system--For the purposes of compliance
with §290.109 of this title (relating to Microbial Contaminants)
and with §290.116 of this title (relating to Groundwater Corrective
Actions and Treatment Techniques), a public water system that provides,
uses, or distributes any groundwater except if the groundwater is
combined with surface water (or with groundwater under the direct
influence of surface water) prior to treatment.
(23) Haloacetic acids (five) (HAA5)--The sum of the
monochloroacetic acid, dichloroacetic acid, trichloroacetic acid,
monobromoacetic acid, and dibromoacetic acid concentrations in milligrams
per liter, rounded to two significant figures after adding the sum.
(24) Halogen--One of the chemical elements chlorine,
bromine, or iodine.
(25) Hydrogeologic sensitivity assessment--A determination
of whether groundwater systems obtain water from hydrogeologically
sensitive sources.
(26) Level 1 assessment--An evaluation to identify
the possible presence of sanitary defects, defects in distribution
system coliform monitoring practices, and (when possible) the likely
reason that the public water system triggered the assessment. Minimum
elements include review and identification of atypical events that
could affect distributed water quality or indicate that distributed
water quality was impaired; changes in distribution system maintenance
and operation that could affect distributed water quality (including,
but not limited to water storage); source and treatment considerations
that bear on distributed water quality, where appropriate; existing
water quality monitoring data; and inadequacies in sample sites, sampling
protocol, and sample processing. The public water system must conduct
the assessment consistent with any executive director directives that
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