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# Cumulative Hydrologic Impact Assessment

### What is a Cumulative Hydrologic Impact Assessment (CHIA)?

A Cumulative Hydrologic Impact Assessment (CHIA) determines whether the mining operation has been designed to prevent material damage to the hydrologic balance outside the permit area.
                - 30 CFR 780.21(g) requires OSMRE to complete a CHIA.
                - 30 CFR 780.21(g)(2) states "an application for permit revision shall be reviewed by the regulatory authority to determine whether a new or updated CHIA shall be required."

A CHIA assesses the probable hydrologic consequences (PHC) of the proposed operation and all anticipated coal mining upon surface and groundwater systems in the cumulative impact area (CIA). The PHC is prepared by the applicant as required by 30 CFR § 780.21(f), and approved by the regulatory authority. The hydrologic reclamation plan required by the rules at 30 CFR § 780.21(h) recognizes that disturbances to the hydrologic balance within the permit and adjacent area should be minimized, material damage outside the permit area should be prevented, applicable Federal, Tribal, and State water quality laws should be met, and the rights of present water users protected.

Additionally, 30 CFR § 816.42 states “discharges of water from areas disturbed by surface mining activities shall be made in compliance with all applicable State and Federal water quality laws and regulations and with the effluent limitations for coal mining promulgated by the US Environmental Protection Agency set forth in 40 CFR part 434.”

##         2023 Review & Analysis of Navajo Aquifer Material Damage Criteria for Peabody Western Coal Company's Kayenta Mine Complex      

                            - Report:  2023 Review & Analysis of Navajo Aquifer Material Damage Criteria for Peabody Western Coal Company's Kayenta Mine Complex
                            - Announcement:  OSMRE Reviews and Analyzes Navajo Aquifer Material Damage Criteria for Kayenta Mine Complex

##         2016 Kayenta Mine Complex      

The 2016 Kayenta Mine Complex CHIA assesses that
                            - the hydrologic monitoring program is adequate for OSMRE’s CHIA,
                            - assesses if impacts within the permit area have been minimized, and
                            - that the operation and reclamation plans are designed to prevent material damage outside the permit area.

This 2016 Kayenta Mine Complex CHIA supersedes the previous Black Mesa Kayenta Mine Complex CHIA’s (OSMRE, 2011), (OSMRE, 2008), (OSMRE, 1989).

View the entire document here: 2016 Kayenta Mine Complex CHIA
                            - Chapter 1 - Introduction
                            - Chapter 2 - Cumulative Impact Area
                            - Chapter 3 - Water Resources Uses and Designations
                            - Chapter 4 - Baseline Hydrologic Conditions
                            - Chapter 5 - Hydrologic Impact Assessments
                            - Chapter 6 - Works Cited
                            - Appendices

 

##         2015 Navajo Mine and Pinabete Permit Areas      

As the regulatory authority for the Navajo Transitional Energy Company (NTEC), a Navajo Nation owned Limited Liability Company (LLC), the Office of Surface Mining Reclamation and Enforcement (OSMRE) is required by 30 Code of Federal Regulations (CFR) § 780.21(g) to complete a cumulative hydrologic impact assessment (CHIA). The CHIA assesses whether the mining operation has been designed to prevent material damage to the hydrologic balance outside the permit area. Federal regulation 30 CFR § 780.21(g) states “an application for permit revision shall be reviewed by the regulatory authority to determine whether a new or updated CHIA shall be required.”

Several administrative activities have prompted the need for a CHIA update. On March 30, 2012, OSMRE received a Permit Application Package (PAP) to develop an approximately 5,600 acre new permit area (Pinabete Permit NM-0042A) to continue surface coal mining and reclamation operations post July 6, 2016 at the Navajo Mine. On May 3, 2013, OSMRE received and application from BNCC, to transfer Federal Permit NM0003F to NTEC.

Additionally, OSMRE approved an electron Permit Application Package (PAP) on June 30, 2014 for Navajo Mine and Pinabete Permit Areas. An initial CHIA was prepared in 1984, and amended in 1989. The CHIA was significantly updated in 2012 to identify material damage thresholds and limits. This 2015 CHIA update in administrative in that it:
                            - Changes the permittee of Federal Permit NM0003F from BNCC to NTEC in text and PAP references,
                            - Clarifies the assessment of two active permit areas (Navajo Mine Permit NM-0003F and The Proposed Pinabete Permit NM-0042A) within the Navajo Tribal Coal Lease, which was completed during the 2012 CHIA update in anticipation of the Pinabete PAP,
                            - Updates illustrations, tables, and text to reflect the Navajo Mine and Pinabete Permit Areas,
                            - Updates ongoing revisions to the hydrologic monitoring program described at Section 5.2 and Appendix H of this document, and
                            - Updates references to locations in the electronic permit application packaged approved on June 30, 2014.

View the entire document here: 2015 Navajo Mine and Pinabete CHIA
                            - Chapter 1 - Introduction
                            - Chapter 2 - Delineation of Cumulative Impact Area
                            - Chapter 3 - Water Resources Uses and Designations
                            - Chapter 4 - Baseline Hydrologic Conditions
                            - Chapter 5 - Hydrologic Impact Assessments
                            - Chapter 6 - Material Damage
                            - Chapter 7 - Works Cited
                            - Appendices

##         2014 John Henry No.1 Mine      

OSMRE is the regulatory authority for Peabody Western Coal Company (PWCC) surface coal mining and reclamation operations at the Kayenta Complex. A revision to PWCC's permit application package was submitted to OSMRE in September, 2010, and OSMRE subsequently determined the CHIA should be updated.

This most current update to the CHIA (2011) replaces the 2008 updated CHIA and the original CHIA written in 1989.

View the entire document here: 2014 John Henry No.1 Mine CHIA
                            - Chapter 1 - Introduction
                            - Chapter 2 - Water Resource Uses and Applicable Water Quality Criteria
                            - Chapter 3 - Characterization of Baseline Hydrologic Conditions
                            - Chapter 4 - Hydrologic Impact Assessment
                            - Chapter 5 - Material Damage Criteria
                            - Chapter 6 - Works Cited
                            - Appendices