UST Check → counties → Ohio → Union
Underground storage tanks & leak sites in Union County, OH
Every figure below is from EPA UST Finder — the EPA-compiled national registry of state-reported underground storage tanks — county aggregates as published by EPA.
96registered tank facilities
118open tanks
195closed tanks
133leak incidents on record
6cleanups still open
6 leak cleanups in
Union County are still open — the state has not closed the case.
An open cleanup near a property you're buying or lending on is a findable, checkable fact: it appears in a
per-address screen with distance and the registry record.
Largest registered facilities
By open-tank count, from the facility-level registry. Every fact is attributed to the EPA record (linked ID); something wrong — use the correction path in the footer and we'll fix or remove it promptly.
| Facility | City | Open / closed tanks | Status | EPA record |
|---|---|---|---|---|
| HONDA RESEARCH & DEVELOPMENT | RAYMOND | 20 / 0 | Open UST(s) | OH80002269 |
| HONDA OF AMERICA, MAP | MARYSVILLE | 13 / 4 | Open UST(s) | OH80003346 |
| COSTCO GASOLINE #1243 | PLAIN CITY | 6 / 0 | Open UST(s) | OH80009700 |
| SMART OIL LLC | MARYSVILLE | 5 / 4 | Open UST(s) | OH80004042 |
| CERTIFIED OIL CO. #059 | MARYSVILLE | 5 / 4 | Open UST(s) | OH80000043 |
| RICHWOOD MINI MART (MARATHON) | RICHWOOD | 5 / 0 | Open UST(s) | OH80000092 |
| STOP & SHOP #304 | MARYSVILLE | 4 / 1 | Open UST(s) | OH80003159 |
| VILLAGE MART (MARATHON) | MARYSVILLE | 4 / 0 | Open UST(s) | OH80002010 |
Open leak cleanups — most recently reported
| Site | City | Reported | Substance | EPA record |
|---|---|---|---|---|
| UNION COUNTY LAND REUTILIZATION CORP (LAND BANK) | MARYSVILLE | 2016-02-05 | — | OH80000085-N00004 |
| PLAIN CITY AUCTION | PALIN CITY | 2013-04-16 | — | OH80009697-N00001 |
| MARYSVILLE MARATHON | MARYSVILLE | 2005-09-02 | — | OH80000064-N00004 |
| SPARROW'S | MARYSVILLE | 2005-06-17 | — | OH80009356-N00002 |
| ROBERT MCWHERTER | MARYSVILLE | 1999-11-09 | — | OH80000010-N00001 |
| CERTIFIED OIL CO. #059 | MARYSVILLE | 1989-07-26 | — | OH80000043-N00001 |
What this means if you're buying or lending here
- "Closed" ≠ clean. A closed tank was taken out of service per the registry — many were closed without soil testing, especially before the late 1990s.
- The registry is incomplete by design. Tanks removed before 1986 and most residential heating-oil tanks were never registered. A county with 96 registered facilities has an unknown number of unregistered ones.
- Open cleanups are the headline. 6 cases in this county are still open; contamination may still be under investigation or remediation — distance from a specific parcel is what matters, and that's a per-address question.
Screen a specific property
This page covers the county. A purchase or loan decision needs the registry around one address: registered tanks at the parcel, every facility within 500 and 1,500 ft, leak cleanups with status and distance — each line cited to the official record.
Screen an address — $49 How it worksThis is a screen of EPA-registered tank and leak records, not an environmental site assessment. State registries are incomplete by design: tanks removed before 1986 and most residential heating-oil tanks were never registered, so a clean screen cannot prove the absence of a tank. "Closed" means a tank was taken out of service per the registry — it does not certify that no contamination remains.
source: EPA UST Finder EPA data vintage 2024-12-04 computed 2026-06-12