1) A Subpart B system supplier
using conventional filtration treatment (as defined in Section
611.101 ) must
operate with enhanced coagulation or enhanced softening to achieve the TOC
percent removal levels specified in subsection (b) unless the supplier meets at
least one of the alternative compliance standards listed in subsection (a)(2)
or (a)(3).
2) Alternative
compliance standards for enhanced coagulation and enhanced softening systems. A
Subpart B system supplier using conventional filtration treatment may use the
alternative compliance standards in subsections (a)(2)(A) through (a)(2)(F) to
comply with this Section in lieu of complying with subsection (b). A supplier
must comply with monitoring requirements in Section
611.382(d).
A) The supplier's source water TOC level,
measured according to Section
611.381(d)(3),
is less than 2.0 mg/l, calculated quarterly as a running annual
average.
B) The supplier's treated
water TOC level, measured according to Section
611.381(d)(3),
is less than 2.0 mg/l, calculated quarterly as a running annual
average.
C) The supplier's source
water TOC level, measured according to Section
611.381(d)(3),
is less than 4.0 mg/l, calculated quarterly as a running annual average; the
source water alkalinity, measured according to Section
611.381(d)(1),
is greater than 60 mg/l (as CaCO
3), calculated quarterly
as a running annual average; and either the TTHM and HAA5 running annual
averages are no greater than 0.040 mg/l and 0.030 mg/l, respectively; or prior
to the effective date for compliance in Section
611.380(b),
the system has made a clear and irrevocable financial commitment, not later
than the effective date for compliance in Section
611.380(b),
to use technologies that will limit the levels of TTHMs and HAA5 to no more
than 0.040 mg/l and 0.030 mg/l, respectively. A supplier must submit evidence
of a clear and irrevocable financial commitment, in addition to a schedule
containing milestones and periodic progress reports for installation and
operation of appropriate technologies, to the Agency for approval. Failure to
install and operate these technologies by the date in the approved schedule
will constitute a violation of an NPDWR.
D) The TTHM and HAA5 running annual averages
are no greater than 0.040 mg/l and 0.030 mg/l, respectively, and the supplier
uses only chlorine for primary disinfection and maintenance of a residual in
the distribution system.
E) The
supplier's source water SUVA, prior to any treatment and measured monthly
according to Section
611.381(d)(4),
is less than or equal to 2.0 l/mg-m, calculated quarterly as a running annual
average.
F) The supplier's finished
water SUVA, measured monthly according to Section
611.381(d)(4),
is less than or equal to 2.0l/mg-m, calculated quarterly as a running annual
average.
3) Additional
Alternative Compliance Standards for Softening Systems. A supplier practicing
enhanced softening that cannot achieve the TOC removals required by subsection
(b)(2) may use the alternative compliance standards in subsections (a)(3)(A)
and (a)(3)(B) in lieu of complying with subsection (b). A supplier must comply
with monitoring requirements in Section
611.382(d).
The alternative compliance standards are as follows:
A) The supplier may undertake softening that
results in lowering the treated water alkalinity to less than 60 mg/l (as
CaCO
3), measured monthly according to Section
611.381(d)(1)
and calculated quarterly as a running annual average; and
B) The supplier may undertake softening that
results in removing at least 10 mg/l of magnesium hardness (as
CaCO
3), measured monthly according to Section
611.381(d)(6)
and calculated quarterly as a running annual average.