(38) Specific ultraviolet absorption at 254 nanometers
(nm) (SUVA)--An indirect indicator of whether the organic carbon in
water is humic or non-humic. It is calculated by dividing a sample's
ultraviolet absorption at a wavelength of 254 nm (UV254) (in inverse
meters) by its concentration of dissolved organic carbon (DOC) (in
milligrams per liter).
(39) Total organic carbon (TOC)--The concentration
of total organic carbon, in milligrams per liter, measured using heat,
oxygen, ultraviolet irradiation, chemical oxidants, or combinations
of these oxidants that convert organic carbon to carbon dioxide, rounded
to two significant figures. TOC is a surrogate measure for precursors
to formation of disinfection by-products.
(40) Total trihalomethanes (TTHM)--The sum of the chloroform,
dibromochloromethane, bromodichloromethane, and bromoform concentrations
in milligrams per liter, rounded to two significant figures after
summing.
(41) Triggered source water monitoring--Raw groundwater
source monitoring required for systems not providing at least 4-log
treatment of viruses when a routine distribution coliform sample is
positive.
(42) Trihalomethane (THM)--One of the family of organic
compounds named as derivatives of methane, wherein three of the four
hydrogen atoms in methane are each substituted by a halogen atom in
the molecular structure.
(43) Wholesale system--A public water system that delivers
water to another public water system.
(44) 4-log treatment--At least 99.99% (4-log) treatment
of viruses using inactivation, removal, or an executive director-approved
combination of 4-log virus inactivation and removal. The 4-log treatment
must be able to be properly validated and achieved before the first
connection of the specified water source.
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Source Note: The provisions of this §290.103 adopted to be effective September 13, 2000, 25 TexReg 8880; amended to be effective May 16, 2002, 27 TexReg 4127; amended to be effective January 9, 2008, 33 TexReg 198; amended to be effective November 8, 2012, 37 TexReg 8849; amended to be effective March 30, 2017, 42 TexReg 1466 |