California Department of Resources Recycling and Recovery (CalRecycle) 

Regulations: Title 27, Environmental Protection--Division 2, Solid Waste

Chapter 7.Special Treatment, Storage, and Disposal Units

Table 1.3  Natural and Artificial Containment Features for Mining Units

Waste Group Waste Management Unit Geologic Setting Liner(s) Hydr. Cond. Values (Units: cm/sec) Leachate Collection and Removal System
A Waste Pile per 2531(b)(1) of Title 23, OR single clay liner1 < 1x10-7   required
  Surface Impoundment or Tailings Pond not applicable double liner, both < 1x10-7outer clay; Inner: clay or synthetic required(2)
B Waste Pile per 20250(b)(1) OR single clay liner < 1x10-6(1) required
  Surface Impoundment or Tailings Pond not applicable double liner, both < 1x10-6// outer : clay or natural permeability(3); inner: clay or synthetic
OR
single replaceable clay liner(4)
required(2)
C Waste Pile, Surface Impoundment, Tailings Pond not applicable not applicable not applicable

(1) Synthetic liner may be used for short-term containment [see 22490(f)(1)].
(2) Liner and leachate collection and removal system for tailings pond must be able to withstand the ultimate weight of wastes.
(3) Permability of < 1x10-6 cm/sec or natural geologic materials may replace outer liner of double liner system.
(4) Single clay liner <(1x10-6 cm/sec) for surface impoundment, to be removed before last 25 percent (minimum 1 foot thickness) of liner is penetrated by fluid, including waste and leachate.

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Last updated: CalRecycle regulations are updated continuously as changes are made and approved by the Office of Administrative Law.
Regulations http://www.calrecycle.ca.gov/Laws/Regulations/
Legal Office: LegalSec@CalRecycle.ca.gov (916) 327-0089