16 Tex. Admin. Code § 12.511 - 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 §
12.514 of this title (relating to
Hydrologic Balance: Siltation Structures) for siltation-structure 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 §
12.522 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
§§12.500-12.510, this section, and §§
12.513-12.572 of this title (relating to
Permanent Program Performance Standards--Underground 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 §§
12.531-12.534 of this title (relating to
Disposal of Underground Development Waste and Excess Spoil: General
Requirements, to Disposal of Underground Development Waste and Excess Spoil:
Valley Fills, to Disposal of Underground Development Waste and Excess Spoil:
Head-of-Hollow Fills, and to Disposal of Underground Development Waste and
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 called for in §
12.524 of this title (relating to
Hydrologic Balance: 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
§§
12.500 -
12.572 of this title (relating to
Permanent Program Performance Standards--Underground Mining Activities) 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 and 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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