30 CFR 784.21 - What requirements apply to preparation, use, and review of the cumulative hydrologic impact assessment (CHIA)?
(1) The regulatory authority must prepare a written assessment of the probable cumulative hydrologic impacts of the proposed operation and all anticipated mining upon surface-water and groundwater systems in the cumulative impact area. This assessment, which is known as the CHIA, must be sufficient to determine, for purposes of permit application approval, whether the proposed operation has been designed to prevent material damage to the hydrologic balance outside the permit area.
(3) As provided in § 784.19(f) of this part, the regulatory authority may not approve a permit application until the hydrologic, geologic, and biological information needed to prepare the CHIA has been made available to the regulatory authority and the regulatory authority has used that information to prepare the CHIA.
(b)Contents. The CHIA must include -
(1) A map of the cumulative impact area. At a minimum, the map must identify and display -
(ii) The locations of all previous, current, and anticipated surface and underground mining.
(2) A description of all previous, existing, and anticipated surface and underground coal mining within the cumulative impact area, including, at a minimum, the coal seam or seams mined or to be mined, the extent of mining, and the reclamation status of each operation.
(i) The quality and quantity of surface water and groundwater and seasonal variations therein.
(ii) The quality and quantity of water needed to support, maintain, or attain each -
(iii) A description and/or maps of the local and regional groundwater systems.
(iv) To the extent required by § 784.19(c)(6)(vi) of this part, the biological condition of perennial and intermittent streams and, to the extent required by § 784.19(c)(6)(viii) of this part, the biology of intermittent streams not included within § 784.19(c)(6)(vi) of this part.
(4) A discussion of any potential concerns identified in the PHC determination required under § 784.20 of this part and how those concerns have been or will be resolved.
(5) A qualitative and quantitative assessment of how all anticipated surface and underground mining may impact the quality of surface water and groundwater in the cumulative impact area, expressed in terms of each baseline parameter identified under § 784.19 of this part.
(6) Site-specific numeric or narrative thresholds for material damage to the hydrologic balance outside the permit area. These thresholds must also be included as a condition of the permit. When identifying thresholds to define when material damage to the hydrologic balance outside the permit area would occur in connection with a particular permit, the regulatory authority will -
(i) In consultation with the Clean Water Act authority, as appropriate, undertake a comprehensive evaluation that considers the following factors -
(A) The baseline data collected under § 784.19 of this part;
(B) The PHC determination prepared under § 784.20 of this part;
(D) Applicable state or tribal standards for surface water or groundwater;
(F) The biological requirements of any species listed as threatened or endangered under the Endangered Species Act of 1973, 16 U.S.C. 1531et seq., when those species; designated critical habitat for those species; habitat occupied by those species, such as nesting, resting, feeding, and breeding areas; and any areas in which those species are present only for a short time, but that are important to their persistence, such as migration and dispersal corridors, are present within the cumulative impact area; and
(G) Other pertinent information and considerations to identify the parameters for which thresholds are necessary.
(ii) In consultation with the Clean Water Act authority, adopt numeric thresholds as appropriate, taking into consideration relevant contaminants for which there are water quality criteria under the Clean Water Act, 33 U.S.C. 1251et seq. The regulatory authority may not adopt a narrative threshold for parameters for which numeric water quality criteria exist under the Clean Water Act, 33 U.S.C. 1251et seq.
(iii) Identify the portion of the cumulative impact area to which each threshold applies. Parameters and thresholds may vary from subarea to subarea within the cumulative impact area when appropriate, based upon differences in watershed characteristics and variations in the geology, hydrology, and biology of the cumulative impact area.
(iv) Identify the points within the cumulative impact area at which the permittee will monitor the impacts of the operation on surface water and groundwater outside the permit area and explain how those locations will facilitate timely detection of the impacts of the operation on surface water and groundwater outside the permit area in a scientifically defensible manner. The permit applicant must incorporate those monitoring locations into the surface water and groundwater monitoring plans submitted under § 784.23 of this part.
(7) Evaluation thresholds for critical water quality and quantity parameters, as determined by the regulatory authority. After permit issuance, if monitoring results at the locations designated under paragraph (b)(6)(iv) of this section document exceedance of an evaluation threshold, the regulatory authority, in consultation with the Clean Water Act authority, as appropriate, must determine the cause of the exceedance. If the mining operation is responsible for the exceedance and if the adverse trend is likely to continue in the absence of corrective action, the regulatory authority must issue a permit revision order under § 774.10 of this chapter. The order must require that the permittee reassess the adequacy of the PHC determination prepared under § 784.20 of this part and the hydrologic reclamation plan approved under § 784.20 of this part and develop measures to prevent material damage to the hydrologic balance outside the permit area.
(9) After consultation with the Clean Water Act authority, as appropriate, an evaluation, with references to supporting data and analyses, of whether the CHIA will support a finding that the operation has been designed to prevent material damage to the hydrologic balance outside the permit area. To support this finding, the CHIA must include the following determinations, with appropriate documentation, or an explanation of why the determination is not necessary or appropriate:
(A) Cause or contribute to a violation of applicable water quality standards adopted under the authority of section 303(c) of the Clean Water Act, 33 U.S.C. 1313(c), or other applicable state or tribal water quality standards;
(ii) The proposed operation has been designed to ensure that neither the mining operation nor the final configuration of the reclaimed area will result in changes in the size or frequency of peak flows from precipitation events or thaws that would cause an increase in flooding outside the permit area, when compared with premining conditions.
(iii) Perennial and intermittent streams located outside the permit area will continue to have sufficient base flow at all times during and after mining and reclamation to maintain their premining flow regime; i.e., perennial streams located outside the permit area will retain perennial flows and intermittent streams located outside the permit area will retain intermittent flows both during and after mining and reclamation. Conversion of an intermittent stream to a perennial stream or conversion of an ephemeral stream to an intermittent or perennial stream outside the permit area may be acceptable, provided the conversion would be consistent with paragraph (b)(9)(i) of this section and would not result in a violation of the Endangered Species Act of 1973, 16 U.S.C. 1531et seq.
(1) The regulatory authority must review each application for a significant permit revision to determine whether a new or updated CHIA is needed. The regulatory authority must document the review, including the analysis and conclusions, together with the rationale for the conclusions, in writing.
(2) The regulatory authority must reevaluate the CHIA at intervals not to exceed 3 years to determine whether the CHIA remains accurate and whether the material damage and evaluation thresholds in the CHIA and the permit are adequate to ensure that material damage to the hydrologic balance outside the permit area will not occur. This evaluation must include a review of all biological and water monitoring data from both this operation and all other coal mining operations within the cumulative impact area.
(3) The regulatory authority must prepare a new or updated CHIA if the review conducted under paragraph (c)(1) or (2) of this section finds that one is needed.
- 30 CFR 784.19 — What Baseline Information on Hydrology, Geology, and Aquatic Biology Must I Provide?
- 30 CFR 784.23 — What Information Must I Include in Plans for the Monitoring of Groundwater, Surface Water, and the Biological Condition of Streams During and After Mining?
- 30 CFR 783.26 — May I Submit Permit Application Information in Increments as Mining Progresses?