General Information Party ID Party Name Party Classification Mailing Address Work Phone Email/Website 487446 MP Mine Operations LLC Privately-Owned Business 67750 Bailey Road Mountain Pass, CA 92366 702-540-2787 sbaker@mpmaterials.com Related Places Place ID Place Name County Region Place Type Relationship to Party Relationship Start Date Relationship End Date 220454 DOMESTIC WASTEWATER T&DFs San Bernardino 6B Wastewater Treatment Facility Owner 07/12/2017 null 246044 Onsite Evaporation Ponds San Bernardino 6B Surface Impoundment Owner 07/12/2017 null 215314 COMMUNITY & CO LANDFILLS-Molycorp San Bernardino 6B Land fill Owner 07/12/2017 null 244589 North Tailing Pond P-16 San Bernardino 6B Metal Mining Owner 07/12/2017 null 241610 Mountain Pass Mine & Mill Ops San Bernardino 6B Metal Mining Owner 07/12/2017 null 757215 Mountain Pass Mine-Revised Mine & Reclamation Plan San Bernardino 6B Dredge/Fill Site Owner 09/28/2010 null 241611 Mountain Pass P-1 Closure San Bernardino 6B Metal Mining Owner 07/12/2017 null 890508 North Overburden Stockpile Development MPMO San Bernardino 6B Dredge/Fill Site Owner 09/25/2023 null Related Parties Party ID Party Name Party Type Role/Relationship Relationship Start Date Relationship End Date Classification 629234 Aaron Case Person Employee 08/01/2019 null null 622685 Steven Baker Person Legally Responsible Official 03/11/2021 null null 605017 John Espinoza Person Employee 07/12/2017 null null 547600 Jeffrey Hogan Person Legally Responsible Official 07/16/2014 07/11/2017 null 508765 Mark Smith Person Owner Contact 06/01/2009 07/11/2017 null Regulatory Measures(non-enforcement) Reg. Measure ID Regulatory Measure Type Region WDID Title Status Program Order No. RM Effective Date RM Termination Date Relationship Relationship Start Date Relationship End Date 454473 Enrollee - WDR 6V 6B362309006 Enrollee - WDR for MP Mine Operations LLC Active CERFILLEXC R6T-2003-0004 03/18/2024 null Discharger 09/25/2023 null 148001 WDR 6V 6B360008001 MOLYCORP INC Mountain Pass Mine and Mill Site (Closure and Post Closure Maintenance) Active LNDISPOTH 00-074 09/14/2000 null Discharger 07/10/2017 null 306717 WDR 6V 6B369706002 Mountain Pass Mine (Community Landfill and Company Landfill) Active LFNONOPER R6V-2006-0024 06/14/2006 null Discharger 07/10/2017 null 133369 WDR 6V 6B369807003 On-Site Evaporation Pond-Molycorp Minerals Active LNDISPOTH R6V-2005-0011 04/14/2005 null Discharger 07/10/2017 null 377626 WDR 6V 6B362098001 Revised WDR-Mountain Pass Mine & Mill Active LNDISPOTH R6V-2010-0047 10/14/2010 null Discharger 07/10/2017 null 132920 WDR 6V 6B360009001 WDR 2004-0042 No Tailings Pond Active LNDISPOTH R6V-2004-0042 10/14/2004 null Discharger 07/10/2017 null 376674 Enrollee - 401 Certification 6V 6B361009001 Mountain Pass Mine-Revised Mine & Reclamation Plan GP# 2003-0004-161 Historical CERFILLEXC R6T-2003-0004 12/02/2010 12/02/2020 Discharger 09/28/2010 null 148025 WDR 6V 6B360011004 Domestic Wastewater Treatment & Disposal Historical WDRMUNIOWTS 01-018 04/11/2001 06/19/2013 Discharger 06/01/2009 null 388260 Enrollee - WDR 6V 6B360011004 97-010-DWQ-15 Molycorp Minerals Active WDRMUNIENROTH 97-010-DWQ 11/07/2012 null Discharger 06/01/2009 null 145895 WDR 6V 6B362098001 WDR 91-836 for Mountain Pass Mine & Mill Historical LNDISP 91-836 06/13/1991 10/14/2010 Discharger 06/01/2009 null Violations within the past calendar year Violation ID Occurrence Date Violation Type Violation Description Violation Status Priority Source Facility Name Violated Reg. Meas. ID Violated Reg. Meas. Order No. Linked To Enf. 1144261 03/17/2025 Unauthorized Discharge 325 gallons of sodium hydroxide spilled. Release was stopped for line repair. On site personnel and equipment including vacuum truck cleaned up solution, impacted soil removed. A line carrying 32% sodium hydroxide ruptured and impacted the ground. The line was turned off, while repairs were being made. The spill was contained and vacuumed up onsite, impacted soil was remediated. ECM Doc handle # 11563968 Violation N Report Mountain Pass Mine & Mill Ops 377626 R6V-2010-0047 N 1144258 09/06/2024 Unauthorized Discharge Cal-OES 24-5040 Line failure caused 32% sodium hydroxide spill onto ground. MPMO staff called Lahontan on Friday for clean up input. Material being pumped into sump and neutralized with weak acid until neutral pH achieved.Reporting party stated that there was a line failure from a line that leads to a tank causing the release onto the ground. The release has been stopped and contained. No storms drains or waterways impacted Violation N Report Mountain Pass Mine & Mill Ops 377626 R6V-2010-0047 N Enforcement Actions Enforcement ID Enforcement Type Enf. Order No. Title Program Effective Date Status 382364 Oral Communication null Molycorp Minerals LLC Spill (11/28/2011) LNDISP 11/28/2011 Historical 388244 Oral Communication null Oral Com 11/27/2012 for Molycorp Minerals LLC LNDISP 11/27/2012 Historical 388275 Notice of Violation null NOV 11/20/2012 for Molycorp Minerals LLC LNDISPOTH 11/20/2012 Active 389533 Oral Communication null Oral Com 09/14/2012 for Molycorp Minerals LLC LNDISP 09/14/2012 Historical 390178 Oral Communication null Oral Com 02/28/2013 for Molycorp Minerals LLC LNDISP 02/28/2013 Historical 393507 Notice of Violation null NOV 10/10/2013 for Molycorp Minerals LLC LNDISPOTH 10/10/2013 Active 394953 Oral Communication null Oral Com 01/09/2014 for Molycorp Minerals LLC WDRMUNIENROTH 01/09/2014 Historical 396973 Oral Communication null Oral Com 09/20/2013 for Molycorp Minerals LLC LNDISPOTH 09/20/2013 Historical 399719 Oral Communication null Oral Com 01/12/2015 for Molycorp Minerals LLC LNDISPOTH 01/12/2015 Historical 399720 Oral Communication null Oral Com 01/15/2015 for Molycorp Minerals LLC LNDISPOTH 01/15/2015 Historical 402399 Oral Communication null Oral Com 07/29/2015 for Molycorp Minerals LLC LNDISPOTH 07/29/2015 Historical 423504 Oral Communication null Oral Com 08/14/2018 for MP Mine Operations LLC LFNONOPER 08/14/2018 Historical 449817 Oral Communication null Oral Com 05/27/2022 for MP Mine Operations LLC LNDISPOTH 05/27/2022 Historical 380390 Staff Enforcement Letter null SEL 07/20/2011 for Molycorp Minerals LLC LNDISP 07/20/2011 Historical 381973 Oral Communication null Molycorp Minerals LLC spill ( 10/10/2011) LNDISP 10/24/2011 Historical 384026 Oral Communication null Oral Com 03/29/2012 for Molycorp Minerals LLC LNDISP 03/29/2012 Historical 394464 Oral Communication null Oral Com 10/08/2013 for Molycorp Minerals LLC LNDISP 10/08/2013 Historical 394956 Oral Communication null Oral Com 01/21/2014 for Molycorp Minerals LLC WDRMUNIENROTH 01/21/2014 Historical 394958 Oral Communication null Oral Com 11/14/2013 for Molycorp Minerals LLC WDRMUNIENROTH 11/14/2013 Historical 396974 Oral Communication null Oral Com 09/23/2013 for Molycorp Minerals LLC LNDISPOTH 09/23/2013 Historical 397929 Oral Communication null Oral Com 08/07/2014 for Molycorp Minerals LLC LNDISPOTH 08/07/2014 Historical 402179 Oral Communication null Oral Com 07/21/2015 for Molycorp Minerals LLC LNDISPOTH 07/21/2015 Historical 425637 Oral Communication null Oral Com 10/11/2018 for MP Mine Operations LLC LNDISPOTH 10/11/2018 Historical 387074 Notice of Violation null NOV 06/08/2012 for Molycorp Minerals LLC LNDISPOTH 06/08/2012 Active 387328 Oral Communication null Oral Com 08/09/2012 for Molycorp Minerals LLC LNDISP 08/09/2012 Historical 388134 Oral Communication null Oral Com 11/06/2012 for Molycorp Minerals LLC LNDISP 11/06/2012 Historical 388942 Notice of Violation null NOV 01/29/2013 for Molycorp Minerals LLC LNDISP 01/29/2013 Historical 389048 Oral Communication null Oral Com 06/01/2012 for Molycorp Minerals LLC LNDISP 06/01/2012 Historical 394379 Notice of Violation null NOV 12/20/2013 for Molycorp Minerals LLC LNDISP 12/20/2013 Active 395386 Oral Communication null Oral Com 02/28/2014 for Molycorp Minerals LLC LNDISP 02/28/2014 Historical 395610 Oral Communication null Oral Com 04/04/2014 for Molycorp Minerals LLC LNDISPOTH 04/04/2014 Historical 397308 Oral Communication null Oral Com 06/09/2014 for Molycorp Minerals LLC LNDISPOTH 06/09/2014 Historical 397332 Oral Communication null Oral Com 07/09/2014 for Molycorp Minerals LLC LNDISPOTH 07/09/2014 Historical 397928 Oral Communication null Oral Com 07/23/2014 for Molycorp Minerals LLC LNDISPOTH 07/23/2014 Historical 399515 Oral Communication null Oral Com 12/15/2014 for Molycorp Minerals LLC LNDISPOTH 12/15/2014 Historical 399730 Oral Communication null Oral Com 01/20/2015 for Molycorp Minerals LLC LNDISPOTH 01/20/2015 Historical 419741 Oral Communication null Oral Com 02/21/2018 for MP Mine Operations LLC LNDISPOTH 02/21/2018 Historical 382499 Oral Communication null Molycorp Minerals LLC Spill (12/8/2011) LNDISP 12/08/2011 Historical 384029 Oral Communication null Oral Com 02/10/2012 for Molycorp Minerals LLC LNDISP 02/10/2012 Historical 390179 Oral Communication null Oral Com 03/08/2013 for Molycorp Minerals LLC LNDISP 03/08/2013 Historical 390181 Oral Communication null Oral Com 04/11/2013 for Molycorp Minerals LLC LNDISP 04/11/2013 Historical 394347 Oral Communication null Oral Com 12/16/2013 for Molycorp Minerals LLC LNDISP 12/16/2013 Historical 394385 Notice of Violation null NOV 12/24/2013 for Molycorp Minerals LLC LNDISP 12/24/2013 Historical 394461 Oral Communication null Oral Com 12/16/2013 for Molycorp Minerals LLC LNDISP 12/16/2013 Historical 428307 Oral Communication null Oral Com 01/02/2019 for MP Mine Operations LLC LNDISPOTH 01/02/2019 Historical 423519 Oral Communication null Oral Com 08/14/2018 for MP Mine Operations LLC LNDISPOTH 08/14/2018 Historical 382062 Notice of Violation null NOV 10/27/2011 for Molycorp Minerals LLC LNDISP 10/27/2011 Historical 389493 Oral Communication null Oral Com 03/05/2013 for Molycorp Minerals LLC LNDISP 03/05/2013 Historical 390177 Oral Communication null Oral Com 01/16/2013 for Molycorp Minerals LLC LNDISP 01/16/2013 Historical 394469 Oral Communication null Oral Com 01/03/2014 for Molycorp Minerals LLC LNDISPOTH 01/03/2014 Historical 396142 Oral Communication null Oral Com 04/23/2014 for Molycorp Minerals LLC LNDISPOTH 04/23/2014 Historical 397167 Oral Communication null Oral Com 06/24/2014 for Molycorp Minerals LLC LNDISPOTH 06/24/2014 Historical 397331 Oral Communication null Oral Com 07/03/2014 for Molycorp Minerals LLC LNDISPOTH 07/03/2014 Historical 423561 Oral Communication null Oral Com 07/23/2018 for MP Mine Operations LLC LNDISPOTH 07/23/2018 Historical 381972 Oral Communication null Molycorp Minerals LLC Spill (10/9/2011) LNDISP 10/10/2011 Historical 389535 Oral Communication null Oral Com 06/01/2012 for Molycorp Minerals LLC LNDISP 06/01/2012 Historical 390176 Oral Communication null Oral Com 01/16/2013 for Molycorp Minerals LLC LNDISP 01/16/2013 Historical 396143 Oral Communication null Oral Com 05/05/2014 for Molycorp Minerals LLC LNDISPOTH 05/05/2014 Historical 398937 Notice of Violation null NOV 11/20/2014 for Molycorp Minerals LLC LNDISPOTH 11/20/2014 Active 428304 Oral Communication null Oral Com 01/02/2019 for MP Mine Operations LLC LNDISPOTH 01/02/2019 Historical 428308 Oral Communication null Oral Com 01/03/2019 for MP Mine Operations LLC LNDISPOTH 01/03/2019 Historical 423516 Oral Communication null Oral Com 08/14/2018 for MP Mine Operations LLC LNDISPOTH 08/14/2018 Historical 382362 Oral Communication null Molycorp Minerals LLC Spill (11/1/2011) LNDISP 11/01/2011 Historical 382505 Oral Communication null Oral Com 12/15/2011 for Molycorp Minerals LLC LNDISP 12/15/2011 Historical 387562 Oral Communication null Oral Com 09/12/2012 for Molycorp Minerals LLC LNDISP 09/12/2012 Historical 389534 Oral Communication null Oral Com 09/24/2012 for Molycorp Minerals LLC LNDISP 09/24/2012 Historical 394136 Oral Communication null Oral Com 12/05/2013 for Molycorp Minerals LLC LNDISP 12/05/2013 Historical 394463 Oral Communication null Oral Com 07/31/2013 for Molycorp Minerals LLC LNDISP 07/31/2013 Historical 394954 Oral Communication null Oral Com 01/21/2014 for Molycorp Minerals LLC WDRMUNIENROTH 01/21/2014 Historical 397002 Oral Communication null Oral Com 06/09/2014 for Molycorp Minerals LLC LNDISPOTH 06/09/2014 Historical 399516 Oral Communication null Oral Com 10/29/2014 for Molycorp Minerals LLC LNDISPOTH 10/29/2014 Historical 399517 Oral Communication null Oral Com 12/19/2014 for Molycorp Minerals LLC LNDISPOTH 12/19/2014 Historical 399866 Oral Communication null Oral Com 01/28/2015 for Molycorp Minerals LLC LNDISPOTH 01/28/2015 Historical 423505 Oral Communication null Oral Com 08/14/2018 for MP Mine Operations LLC LNDISPOTH 08/14/2018 Historical 423513 Oral Communication null Oral Com 08/14/2018 for MP Mine Operations LLC LNDISPOTH 08/14/2018 Historical 423514 Oral Communication null Oral Com 08/14/2018 for MP Mine Operations LLC LNDISPOTH 08/14/2018 Historical 429031 13267 Letter null 13260 Letter for GILTON RESOURCE RECOVERY TRANSFER FACILITY WDRINDIVSML 02/20/2019 Historical 388247 Oral Communication null Oral Com 11/27/2012 for Molycorp Minerals LLC LNDISP 11/27/2012 Historical 391807 Oral Communication null Oral Com 06/17/2013 for Molycorp Minerals LLC LNDISP 06/17/2013 Historical 392999 Staff Enforcement Letter null SEL 08/08/2013 for Molycorp Minerals LLC LNDISP 08/08/2013 Historical 394880 Oral Communication null Oral Com 01/15/2014 for Molycorp Minerals LLC LNDISP 01/15/2014 Historical 399518 Oral Communication null Oral Com 12/18/2014 for Molycorp Minerals LLC LNDISPOTH 12/18/2014 Historical 400262 Oral Communication null Oral Com 03/02/2015 for Molycorp Minerals LLC LNDISPOTH 03/02/2015 Historical 401788 Oral Communication null Oral Com 06/29/2015 for Molycorp Minerals LLC LNDISPOTH 06/29/2015 Historical 397425 Clean-up and Abatement Order R6V-2014-0062 CAO R6V-2014-0062 for Molycorp Minerals LLC LNDISPOTH 07/22/2014 Active Regulatory Measures linked to Related Parties Reg. Measure ID Organization Regulatory Measure Type Program Effective Date Status 388260 Aaron Case Enrollee - WDR WDRMUNIENROTH 11/07/2012 Active 377626 John Espinoza WDR LNDISPOTH 10/14/2010 Active 306717 John Espinoza WDR LFNONOPER 06/14/2006 Active 133369 John Espinoza WDR LNDISPOTH 04/14/2005 Active 132920 John Espinoza WDR LNDISPOTH 10/14/2004 Active 148001 John Espinoza WDR LNDISPOTH 09/14/2000 Active