16 Tex. Admin. Code § 12.341 - Hydrologic Balance: Diversions
(a)
General Requirements.
(1) With the approval
of the Commission, any flow from mined areas abandoned before May 3, 1978, and
any flow from undisturbed areas or reclaimed areas, after meeting the criteria
of §
12.344 of this title (relating to
Hydrologic Balance: Sedimentation Ponds) for siltation structures removal, may
be diverted from disturbed areas by means of temporary or permanent diversions.
All diversions shall be designed to minimize adverse impacts to the hydrologic
balance within the permit and adjacent areas, to prevent material damage
outside the permit area and to assure the safety of the public. Diversions
shall not be used to divert water into underground mines without approval of
the Commission under §
12.353 of this title (relating to
Hydrologic Balance: Discharge of Water Into an Underground Mine).
(2) The diversion and its appurtenant
structures shall be designed, located, constructed, maintained and used to:
(A) be stable;
(B) provide protection against flooding and
resultant damage to life and property;
(C) prevent, to the extent possible using the
best technology currently available, additional contributions of suspended
solids to streamflow outside the permit area; and
(D) comply with all applicable local, state,
and federal laws and regulations.
(3) Temporary diversions shall be removed
when no longer needed to achieve the purpose for which they were authorized.
The land disturbed by the removal process shall be restored in accordance with
§§12.330-12.340, this section, and §§ 12.342-12.403 of this title (relating to
Permanent Program Performance Standards--Surface Mining Activities). Before
diversions are removed, downstream water-treatment facilities previously
protected by the diversion shall be modified or removed, as necessary, to
prevent overtopping or failure of the facilities. This requirement shall not
relieve the operator from maintaining water-treatment facilities as otherwise
required. A permanent diversion or a stream channel reclaimed after the removal
of a temporary diversion shall be designed and constructed so as to restore or
approximate the premining characteristics of the original stream channel
including the natural riparian vegetation to promote the recovery and the
enhancement of aquatic habitat.
(4)
Diversion designs shall incorporate the following:
(A) be constructed with gentle sloping banks
that are stabilized by vegetation. Asphalt, concrete or other similar linings
shall be used only when approved by the Commission to prevent seepage or to
provide stability. Channel linings shall be designed using standard engineering
practices to pass safely the design velocities and shall be approved for
permanent diversions only where they are stable and will require infrequent
maintenance;
(B) erosion protection
shall be provided for transition of flows and for critical areas such as swales
and curves;
(C) energy dissipators
shall be installed when necessary at discharge points, where diversions
intersect with natural streams and exit velocities of the diversion ditch flow
is greater than that of the receiving stream;
(D) excess excavated material not necessary
for diversion channel geometry or regrading of the channel shall be disposed of
in accordance with §§
12.363-12.366 of this title (relating to
Disposal of Excess Spoil: General Requirements, to Disposal of Excess Spoil:
Valley Fills, to Disposal of Excess Spoil: Head-of-Hollow Fills, and to
Disposal of Excess Spoil: Durable Rock Fills); and
(b) Diversions of Perennial and Intermittent
Streams.
(1) Diversions of perennial and
intermittent streams within the permit area may be approved by the Commission
after making the finding relating to stream buffer zones that the diversion
will not adversely affect the water quantity and quality and related
environmental resources of the stream.
(2) The design capacity of channels for
temporary and permanent stream channel diversions shall be at least equal to
the capacity of the unmodified stream channel immediately upstream and
downstream from the diversion.
(3)
The requirements of subsection (a)(2)(B) of this section shall be met when the
temporary and permanent diversions for perennial and intermittent streams are
designed so that the combination of channel, bank and floodplain configuration
is adequate to pass safely the peak runoff of a 10-year, 6-hour precipitation
event for a temporary diversion and a 100-year, 6-hour precipitation event for
a permanent diversion.
(4) The
design and construction of all stream channel diversions of perennial and
intermittent streams shall be certified by a qualified professional engineer as
meeting the performance standards of this part and any design criteria set by
the Commission.
(c)
Diversion of Miscellaneous Flows.
(1)
Miscellaneous flows, which consists of all flows except for perennial and
intermittent streams, may be diverted away from disturbed areas if required or
approved by the Commission. Miscellaneous flows shall include ground-water
discharges and ephemeral streams.
(2) The design, location, construction,
maintenance, and removal of diversions of miscellaneous flows shall meet all of
the performance standards set forth in subsection (a) of this
section.
(3) The requirements of
subsection (a)(2)(B) of this section shall be met when the temporary and
permanent diversions for miscellaneous flows are designed so that the
combination of channel, bank and flood-plain configuration is adequate to pass
safely the peak runoff of a 2-year, 6-hour precipitation event for a temporary
diversion and a 10-year, 6-hour precipitation event for a permanent
diversion.
Notes
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