Clean Air Act stationary source · ICIS-AIR PA000708698
MARKWEST LIBERTY MIDSTREAM & RESOURCES/NANCY STEWART, Mount Pleasant, PA: Clean Air Act compliance record, inspections, violations, penalties
- OperatingOperating status
- Synthetic minor sourceEmissions classification
- No Violation IdentifiedCurrent violation status, as filed
- 14Compliance evaluations since January 1, 2017
- 0High-priority violations since January 1, 2017
- 2Formal enforcement actions since January 1, 2017
MARKWEST LIBERTY MIDSTREAM & RESOURCES/NANCY STEWART, at HWY 231, Mount Pleasant in Washington County, Pennsylvania, is an operating synthetic minor source of air pollution on EPA’s ICIS-AIR register. EPA’s file records its current violation status (ICIS-AIR’s high-priority violation field) as “No Violation Identified”. Washington County is on EPA’s Green Book list of areas that do not meet a national air quality standard. The status and classification are as EPA’s facility file stood when Velarion loaded it (September 14, 2026); EPA’s free Detailed Facility Report on ECHO carries the source’s current standing, quarter by quarter.
Identity
| Facility as filed | MARKWEST LIBERTY MIDSTREAM & RESOURCES/NANCY STEWART |
|---|---|
| ICIS-AIR ID | PA000708698 |
| EPA facility registry ID | 110043577457 |
| Operating status | Operating |
| Emissions classification | Synthetic minor source |
| Current violation status (ICIS-AIR high-priority violation field) | No Violation Identified |
| Address | HWY 231, Mount Pleasant, PA 15340 |
| County | Washington County |
| In a nonattainment county | Yes (EPA Green Book) |
| Industry (NAICS) | Mining support (NAICS 2131) |
| SIC code | 1311 |
| EPA region | 03 |
Cited to the EPA ICIS-AIR facility file (ECHO download).
Programs and pollutants
Velarion’s copy of EPA’s ICIS-AIR download does not include its program, pollutant and Title V certification files, so this page does not list the Clean Air Act programs MARKWEST LIBERTY MIDSTREAM & RESOURCES/NANCY STEWART is under or the pollutants it is permitted for. The programs each evaluation and violation below was recorded under are shown with it. EPA’s free Detailed Facility Report lists both.
Compliance evaluations
- 14Evaluations since January 1, 2017
- 3Full compliance evaluations
| Date | What EPA recorded | Agency | Programs |
|---|---|---|---|
| July 23, 2026 | FCE On-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| April 21, 2026 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| June 7, 2025 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| May 2, 2024 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| July 5, 2023 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| June 13, 2022 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| May 7, 2021 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| March 22, 2021 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| January 7, 2021 | FCE On-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| May 29, 2020 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| May 22, 2019 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| October 16, 2018 | FCE On-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| March 29, 2018 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
| March 16, 2017 | PCE Off-Site | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
Violations
- 1Violation determinations since January 1, 2017
- 0Of them high-priority
A high-priority violation (HPV) is the most serious class of Clean Air Act non-compliance an agency records; a federally reportable violation (FRV) is the next step down. Each row is one determination as EPA’s violation history files it.
| Date | What EPA recorded | Agency | Programs |
|---|---|---|---|
| June 17, 2020 | Earliest FRV determination | State | State Implementation Plan for National Primary and Secondary Ambient Air Quality Standards |
Enforcement and penalties
2 formal enforcement actions since January 1, 2017, 2 of them with a penalty filed above zero. Each penalty is shown as EPA’s formal action file states it; “Not stated” means the file gives no figure, and $0 is a disclosed zero.
| Date | What EPA recorded | Agency | Penalty, as filed |
|---|---|---|---|
| September 6, 2021 | Administrative Order | State | $19,500 |
| July 9, 2018 | Civil Judicial Action | U.S. EPA | $385,000 |
Informal enforcement
| Date | What EPA recorded | Agency |
|---|---|---|
| March 22, 2021 | Notice of Violation | State |
Stack tests
- 20Stack tests since January 1, 2017
- 0Recorded as failed
| Date | What EPA recorded | Agency |
|---|---|---|
| June 23, 2026 | Pass | State |
| February 12, 2026 | Pass | State |
| February 20, 2025 | Pass | State |
| April 4, 2024 | Pass | State |
| February 26, 2024 | Pass | State |
| April 13, 2023 | Pass | State |
| February 27, 2023 | Pass | State |
| April 13, 2022 | Pass | State |
| March 2, 2022 | Pass | State |
| April 13, 2021 | Pass | State |
| March 3, 2021 | Pass | State |
| April 15, 2020 | Pass | State |
| March 6, 2020 | Pass | State |
| April 17, 2019 | Pass | State |
| March 8, 2019 | Pass | State |
| May 3, 2018 | Pass | State |
| March 6, 2018 | Pass | State |
| October 11, 2017 | Pass | State |
| June 9, 2017 | Pass | State |
| March 11, 2017 | Pass | State |
Cited to the EPA ICIS-AIR evaluation, violation, stack test and enforcement files (ECHO download), events dated January 1, 2017 or later as loaded; up to 50 rows of each shown, newest first.
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How we handle your data → Privacy
EPA publishes a free Detailed Facility Report for every source on ECHO: its compliance status quarter by quarter, its evaluations, and its violations, enforcement actions and penalties. EPA also sends free notices of new inspections and enforcement actions through ECHO Notify; enter EPA facility registry ID 110043577457 there.
Nearby on the register
- Air-emissions sources in Washington County
- Every source record in Washington County, A to Z
- Air-emissions sources in Pennsylvania
- Every source record in Pennsylvania, A to Z
Figures from EPA’s ICIS-AIR download, loaded September 14, 2026.