25 Pa. Code § 89.23. Diversion and conveyance of overland flow.

§ 89.23. Diversion and conveyance of overland flow.

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.

Source

   The provisions of this §  89.23 adopted December 19, 1980, 10 Pa.B. 4789, effective July 31, 1982, 12 Pa.B. 2382; amended July 30, 1982, 12 Pa.B. 2473, effective July 31, 1982, 12 Pa.B. 2382.

Cross References

   This section cited in 25 Pa. Code §  89.173 (relating to performance standards).

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