§ 20250. SWRCB -Class II: Waste Management Units for Designated Waste. (C15: s2532)
(a) General -Class II waste management units (Class II Units) shall be located where site characteristics and containment structures isolate waste from waters of the state. The classification criteria in this section shall be used for reclassification of existing Units at disposal sites approved as Class II-1 under previous versions of these SWRCB regulations, and for existing Units used for treatment or for storage, whether or not classified, provided that no hazardous wastes other than those which DTSC has determined need not be discharged as a hazardous waste) have been discharged at such Units (including discharge at any expansion of such Units).
(b) Geologic Setting.
(1) New and existing Class II landfills or waste piles shall be immediately underlain by natural geologic materials which have a hydraulic conductivity of not more than 1x10-6 cm/sec (i.e., 1 foot/year) and which are of sufficient thickness to prevent vertical movement of fluid, including waste and leachate, from Units to waters of the state for as long as wastes in such units pose a threat to water quality. Class II units shall not be located where areas of primary (porous) or secondary (rock opening) hydraulic conductivity greater than 1x10-6 cm/sec (i.e., 1 foot/year) could impair the competence of natural geologic materials to act as a barrier to vertical fluid movement.
(2) Natural or artificial barriers shall be used to prevent lateral movement of fluid, including waste and leachate.
(3) A liner system which conforms to the requirements of Article 4 of this subchapter with a hydraulic conductivity of not more than 1x10-6 cm/sec (i.e., 1 foot/year) shall be used for landfills and waste piles when natural geologic materials do not satisfy the requirements in (b)(1).
(4) Class II surface impoundments are not required to comply with the requirements of (b)(1), but shall have a liner system designed in accordance with the applicable SWRCB- promulgated provisions of Article 4 of this subchapter (s20310 et seq.). The RWQCB can allow Class II surface impoundments which are designed and constructed with a double liner system in accordance with that article to use natural geologic materials which comply with (b)(1) for the outer liner.
(5) Land treatment units (LTUs) are not required to comply with the requirements of (b). Dischargers who treat or dispose of wastes in LTUs shall demonstrate, prior to application of the waste, that waste can be completely degraded, transformed, or immobilized in the treatment zone. To demonstrate this, prior to the application of waste, the discharger shall operate a test plot for a sufficient period to give the RWQCB a reasonable indication that degradation, transformation, or immobilization will take place in the treatment zone. During the full-scale operation of the LTU, soil and soil-pore liquid samples shall be taken within the treatment zone to verify that complete degradation, transformation, or immobilization is taking place. The RWQCB shall specify in WDRs the elements of the land treatment program including the dimensions of the treatment zone. The maximum depth of the treatment zone shall not exceed 5 feet from the initial soil surface.
(c) Flooding -New and existing Class II Units shall be designed, constructed, operated, and maintained to prevent inundation or washout due to floods with a 100-year return period. MSW landfills are also subject to any more-stringent flood plain and wetland siting requirements referenced in SWRCB Resolution No. 93-62 (i.e., see s258.11 and s258.12 of 40CFR258).
(d) Ground Rupture -New Class II Units, other than LTUs and expansions of existing Class II units, shall have a 200-foot setback from any known Holocene fault. Other units (that are subject to this section) can be located within 200 feet of a known Holocene fault, provided the RWQCB finds that the Unit's containment structures are capable of withstanding ground accelerations associated with the maximum credible earthquake.
(e) Rapid Geologic Change -New and existing Class II Units can be located within areas of potential rapid geologic change only if the RWQCB finds that the Unit's containment structures are designed, constructed, and maintained to preclude containment failure. MSW landfills are also subject to any more-stringent unstable area siting requirements referenced in SWRCB Resolution No. 93-62 (i.e., see s258.15 and s258.16 of 40CFR258).
(f) Tidal Waves -New and existing Class II Units may be located in areas subject to tsunamis, seiches, and surges. Other Units may be located within these areas if designed, constructed, and maintained to preclude failure due to such events.(1. New section filed 6-18-97; operative 7-18-97 (Register 97, No. 25). 2. Change without regulatory effect amending subsection (c) filed 3-17-98 pursuant to section 100, title 1, California Code of Regulations (Register 98, No. 12).)
Note: Authority cited: Section 1058, Water Code. Reference: Sections 13172 and 13360, Water Code; and Section 43103, Public Resources Code.
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