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

Chapter 7. Special Treatment, Storage, and Disposal Units

Subchapter 1. Mining Waste Management

Article 1. SWRCB - Mining Waste Management Regulations (C15: Article 7)

[Note: Regulations in this article were promulgated by the State Water Resources Control Board (SWRCB), are administered by the appropriate Regional Water Quality Control Board (RWQCB) through the issuance of waste discharge requirements (WDRs), and are applicable to the owner or operator of a waste management unit for the treatment, storage, or disposal of mining waste (Mining Unit).]

(a) General — This article applies to all discharges of mining wastes. No SWRCB-promulgated parts of this subdivision except those in this article, Article 1 of Chapter 1 (i.e., section 20080 et seq.), and such provisions of the other articles of this subdivision as specifically are referenced in this article shall apply to discharges of "mining wastes" as that term is defined in section 22480. Mining Units (including surface impoundments, waste piles, and tailings ponds) which receive WDRs after November 27, 1984, shall comply with the siting and construction standards in this article. Existing active and inactive Mining Units shall comply with the siting and construction requirements of this article as required by the RWQCB. Dischargers shall submit a report of waste discharge in compliance with Article 4, Subchapter 3, Chapter 4 of this subdivision (section 21710 et seq.), and shall have WDRs which implement the appropriate provisions of this article unless requirements are waived by the RWQCB. Requirements for new and existing Mining Units are summarized on table 1.1 of this article. The RWQCB can impose more stringent requirements to accommodate regional and site specific conditions.

(b) Dry Unit Liner/LCRS Exemption — A RWQCB can exempt a mining waste pile from the liners and leachate collection and removal systems required in this article if the discharger clearly demonstrates to the RWQCB that leachate will not form in or escape from that Mining Unit. The RWQCB can require extensive monitoring procedures in lieu of certain containment features. Contingency plans shall be developed and shall be implemented if monitoring indicates that the disposal procedures are inadequate.

(c) Exemptions Based On No/Little/Poor G.W. — The RWQCB can exempt a Group A or B (see section 22480 of this article) Mining Unit from certain provisions of this article if a comprehensive hydrogeologic investigation demonstrates that:

(1) there are only very minor amounts of groundwater underlying the area; or

(2) the discharge is in compliance with the applicable water quality control plan; and

(3) either natural conditions or containment structures will prevent lateral hydraulic interconnection with natural geologic materials containing ground water suitable for agricultural, domestic, or municipal beneficial uses. There is no detectable vertical hydraulic interconnection between the natural geologic materials underlying the Unit and natural geologic materials containing such ground water.  If the above demonstration is acceptable to the RWQCB, the discharger can be exempted from requirements for liners and leachate collection and removal systems (see section 22490 of this article). However, the discharger shall comply with the requirements of this article relative to siting, precipitation and drainage controls, and surface water quality monitoring. Closure and post closure maintenance periods shall be designed to protect surface water quality. Ground water monitoring, and unsaturated zone monitoring as feasible, shall be conducted during the active life, closure, and post closure maintenance period to verify that the Unit is not affecting ground water suitable for agricultural, domestic, or municipal beneficial uses.

Note:

Authority cited:
Section 1058, Water Code.

Reference:
Sections 13172, 13226, 13260, and 13263, Water Code; Section 43103, Public Resources Code.

(a) Definition — Mining waste is waste from the mining and processing of ores and mineral commodities. Mining waste includes:

(1) overburden;

(2) natural geologic material which have been removed or relocated but have not been processed (waste rock); and

(3) the solid residues, sludges, and liquids from the processing of ores and mineral commodities.

(b) Waste Group Classification — Mining wastes shall be classified as Group A, Group B, or Group C mining wastes based on an assessment of the potential risk of water quality degradation posed by each waste. In setting requirements for each mining waste discharge under this article, the RWQCB shall assign the waste to Group A, Group B, or Group C according to the following criteria:

1. Group A — mining wastes of Group A are wastes that must be managed as hazardous waste pursuant to Chapter 11 of Division 4.5, of Title 22 of this code, provided the RWQCB finds that such mining wastes pose a significant threat to water quality;

2. Group B — mining waste of Group B are either:

(A) mining wastes that consist of or contain hazardous wastes, that qualify for a variance under Chapter 11 of Division 4.5, of Title 22 of this code, provided that the RWQCB finds that such mining wastes pose a low risk to water quality; or

(B) mining wastes that consist of or contain nonhazardous soluble pollutants of concentrations which exceed water quality objectives for, or could cause, degradation of waters of the state; or

3. Group C — mining wastes from Group C are wastes from which any discharge would be in compliance with the applicable water quality control plan, including water quality objectives other than turbidity.

(c) Classification Considerations — In reaching decisions regarding classification of a mining waste as a Group B or Group C waste, the RWQCB can consider the following factors:

(1) whether the waste contains hazardous constituents only at low concentrations;

(2) whether the waste has no or low acid generating potential; and

(3) whether, because of its intrinsic properties, the waste is readily containable by less stringent measures.

(d) Treatment — Mining waste shall be treated or neutralized whenever feasible to minimize the threat to water quality and minimize the need to install waste containment structures.

Note:

Authority cited:
Section 1058, Water Code.

Reference:
Sections 13172, Water Code; Section 43103, Public Resources Code.

(a) Proximity to Faults — New Mining Units:

(1) for Group A and B wastes, shall not be located on Holocene faults. Units for Group C wastes may be located on Holocene faults if displacement will not allow escape of wastes or cause irreparable damage to containment structures;

(2) shall be outside of areas of rapid geologic change. Exemptions may be allowed by the RWQCB if containment structures are designed and constructed to preclude failure.

(b) Flooding — All Mining Units shall be protected from flooding as shown on Table 1.2 of this article.

(c) Construction & Discharge Standards — General construction standards are given on Table 1.3 of this article. Procedures for determining appropriate methods for discharges of Groups A and B mining wastes are outlined in Figures 1.1 and 1.2 of this article.

(d) Registered Professionals — Containment structures shall be designed by a registered civil engineer, and construction shall be supervised and certified by a registered civil engineer or a certified engineering geologist.

(e) General Containment Structure Criteria — Dischargers shall comply with general criteria for containment structures in section 20320.

(f) Liners.

(1) FMLs — Synthetic liners (40 mil minimum thickness) can be used for waste piles where the discharger can demonstrate that the liner will function adequately during the active life of the waste pile and provided that the waste pile is closed in accordance with section 21410.

(2) Relative Permeability — Permeabilities shall be relative to the fluids, including waste or leachate, to be contained.

(3) Clay Liners — Clay liners shall be of a minimum of two feet thick and shall be installed at relative compaction of at least 90 percent.

(4) Replaceable Clay-Liners — Single clay liners may be used for Group B surface impoundments if replaced as specified in section 20330(e).

(5) Contingency Plan — If the RWQCB exempts a discharger from liner requirements for a waste pile, a contingency plan for alternative waste containment shall be developed. The plan shall be implemented if there is failure of the waste pile containment system.

(6) Dischargers shall comply with the liner criteria given in section 20330(a & d).

(g) Leachate Collection and Removal Systems (LCRSs) for Group A and B Wastes.

(1) All LCRSs shall be of the blanket type.

(2) Dischargers shall comply with leachate collection and removal system (LCRS) requirements given in section 20340(b - e).

(h) Precipitation and Drainage Controls.

(1) Design Storm — Diversion and drainage facilities shall be designed and constructed to accommodate the anticipated volume of precipitation and peak flows from surface runoff as follows:

(A) Group A — one 25 year, 24 hour storm;

(B) Group B — one 10 year, 24 hour storm; and

(C) Group C — one 10 year, 24 hour storm.

(2) Excess Runoff — Precipitation on Group A and B waste piles that is not diverted by containment structures shall be collected and managed through the LCRS. The RWQCB can make exemptions to this requirement if the collected fluid does not contain indicator parameters or waste constituents in excess of applicable water quality objectives.

(3) Precipitation/Drainage Controls — Dischargers shall comply with precipitation and drainage control requirements given in section 20365(d & e).

(i) Incorporated Impoundment Requirements — Dischargers shall comply with special requirements for surface impoundments given in section 20375. Nevertheless, for Mining Units, dischargers shall use the precipitation conditions in (h)(1).

Note:

Authority cited:
Section 1058, Water Code.

Reference:
Sections 13172, 13226, and 13263, Water Code; Section 43103, Public Resources Code.

(a) General — New and existing Group A and B Mining Units shall comply with the monitoring provisions contained in section 20385 through section 20430.

(b) Monitoring Mandatory — If a waste pile containing Group A or B mining wastes is granted exemption from construction requirements pursuant to section 22470(b), monitoring of the waste moisture content shall be required.

Note:

Authority cited:
Section 1058, Water Code.

Reference: 
Sections 13172, 13226, 13263, and 13267, Water Code; Section 43103, Public Resources Code.

(a) Closure Performance Standard — New and existing Mining Units shall be closed so that they no longer pose a threat to water quality. No post closure land uses shall be permitted that might impair the integrity of containment structures.

(b) Plan — Mining Units shall be closed according to an approved closure and post closure maintenance plan which implements this section and provides for continued compliance with the applicable standards in this article for waste containment, precipitation and drainage controls, and monitoring throughout closure and the post closure maintenance period.

(c) Reclamation — The RWQCB shall issue WDRs which incorporate the relevant provisions of an approved mining and reclamation plan (see California Surface Mining and Reclamation Act, Public Resources Code, Section 2770, et seq.), prescribe additional conditions as necessary to prevent water quality degradation, and ensure that there will be no significant increase in the concentration of indicator parameters or waste constituents in ground or surface water, unless requirements are waived.

(d) Oversight & Monuments — Dischargers shall comply with the closure requirements given in section 20950(b & d).

(e) Inactive Units — Containment structures at inactive Mining Units shall be subject to the same standards as apply to an active Mining Unit under this article.

(f) Closure and Post-Closure Funding — The discharger shall provide for adequate funding to pay for the costs of closure and post closure maintenance as required by this article. The discharger shall provide assurance of financial responsibility, acceptable to the RWQCB, pursuant to Chapter 6 of this title. The RWQCB shall periodically review financial assurances and shall modified them as necessary.

(g) Alternate Financial Assurance — If a lead agency acting under the authority of section 2774(a) of the Public Resources Code requires assurances of financial responsibility, these assurances can be used to fulfill all comparable requirements under (f), provided that:

(1) the RWQCB approves the assurance; and

(2) the RWQCB is named as alternate payee.

(h) Ending Post-Closure — The post closure maintenance period shall end when the RWQCB determines that water quality aspects of reclamation are complete and waste no longer poses a threat to water quality.

(i) Vegetation — Vegetation for closed Mining Units shall not impair the integrity of containment features. Irrigation of vegetation shall be managed to assure that it does not cause nor increase the production of leachate.

(j) Waste Pile Closure Standards — New and existing Group A and B waste piles shall be closed in accordance with the provisions of section 21090(a - c).

(k) Surface Impoundment Closure Standards — New and existing Group A and B surface impoundments shall be closed in accordance with the provisions of paragraphs (a) and (b)(1) of section 21400. A surface impoundment can be closed in place if provided with a cover as in section 21090(a) and if the liner (or, in the case of a double liner system, the outer liner) is clay.

(l) Tailings Pond Closure Standards — New and existing Group A and B tailings ponds shall be closed in accordance with the provisions of section 21090(a - c)and section 21400(a).

(m) Erosion & Sedimentation Protection — New and existing Group C Mining Units shall be closed in a manner that will minimize erosion and the threat of water quality degradation from sedimentation.

Note:

Authority cited:
Section 1058, Water Code.

Reference:
Sections 13172, 13226, and 13263, Water Code; Section 43103, Public Resources Code.

Table 1.1 Summary of Requirements for New and Existing Mining Units

Table 1.2 Floodplain Sitting Criteria

Last updated: March 21, 2008