Overland flow, shallow groundwater flow from
undisturbed areas and flow in ephemeral streams shall, unless otherwise
approved by the Department, be diverted away from disturbed areas by means of
temporary or permanent diversions to minimize accelerated erosion, to reduce
the volume of water to be treated, and to prevent contact with
pollution-forming materials. The following requirements shall be met for all
diversions:
(1) Temporary diversions
shall be constructed to safely pass the peak runoff from a precipitation event
with a 2-year recurrence interval, or a larger event as specified by the
Department.
(2) Permanent diversions
shall be constructed to safely pass the peak runoff from a precipitation event
with a 10-year recurrence interval, or a larger event as specified by the
Department. Permanent diversions shall be constructed with gently sloping banks
that are stabilized.
(3) Using the
best technology currently available, diversions shall be designed, constructed
and maintained in a manner which prevents additional contributions of suspended
solids to streamflow and runoff outside the disturbed area.
(4) A diversion may not be located in a way
which will increase the potential for landslides.
(5) When no longer needed, each temporary
diversion shall be removed and the affected land shall be regraded, have
topsoil applied and be revegetated in accordance with §§
89.84-
89.86 (relating to backfilling and
grading; topsoil use; and revegetation).
(6) Diversion design shall incorporate the
following:
(i) Channel linings to safely pass
the design velocities.
(ii)
Adequate freeboard.
(iii) Energy
dissipators when necessary.
Notes
The
provisions of this § 89.23 adopted December 19, 1980, 10 Pa.B. 4789,
effective 7/31/1982, 12 Pa.B.
2382; amended July 30, 1982, 12 Pa.B. 2473, effective
7/31/1982, 12 Pa.B.
2382.
This section cited in 25 Pa. Code §
89.173 (relating to performance
standards).
