Data / Mines / Wisconsin / Portable Unit #4
Portable Unit #4, Rock County, Wisconsin: 0 MSHA citations
Updated November 6, 2026. Source: US Department of Labor, Mine Safety and Health Administration (MSHA), Open Government Data Sets.
Portable Unit #4 is an active crushed, broken limestone surface mine in Rock County, Wisconsin, operated by Bjoin Limestone Inc with 3 employees on MSHA's record (mine ID 4703709). Since January 1, 2022 MSHA inspectors issued 0 citations and orders there with $0 in proposed penalties, and 0 accident reports were filed there, with no injury or illness cases.
The request: Watch Portable Unit #4 (MSHA mine ID 4703709) in Rock County, Wisconsin: each new citation and each accident report. $10 of work on sign-up, no card.
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- MSHA mine ID
- 4703709
- Status
- Active since November 5, 2025
- Main commodity
- Crushed, broken limestone
- Mine type
- Surface
- County
- Rock County, Wisconsin
- Nearest town
- Janesville
- Operator
- Bjoin Limestone Inc
- Employees
- 3
- MSHA field office
- Peru IL Field Office
- Citations and orders since January 1, 2022
- 0
- Inspections
- 6
- Inspector hours on site
- 24
- Citations per inspection
- 0.00 (all mines 2.30)
- Accident reports
- 0
- Injury and illness cases
- 0
- Fatalities
- 0
- Latest MSHA record
- August 7, 2026
Other open mines in Rock County, Wisconsin
| Mine | Operator | County | Main commodity | Employees | Citations since 2022 |
|---|---|---|---|---|---|
| Nordberg | Southern Wisconsin Aggregate Corporation | Rock County, WI | Crushed, broken limestone | 4 | 25 |
| Janesville Pit and Mill | Janesville Sand & Gravel Co. | Rock County, WI | Construction sand and gravel | 10 | 16 |
| Portable Unit #2 | Bjoin Limestone Inc | Rock County, WI | Crushed, broken limestone | 4 | 10 |
| Prairie Sand & Gravel | Prairie Avenue Concrete, Inc. | Rock County, WI | Construction sand and gravel | 2 | 10 |
| Portable Unit #1 | Bjoin Limestone Inc | Rock County, WI | Crushed, broken limestone | 3 | 9 |
| Pioneer Jaw | Southern Wisconsin Aggregate Corporation | Rock County, WI | Construction sand and gravel | 2 | 9 |
| Cronin | Southern Wisconsin Aggregate Corporation | Rock County, WI | Construction sand and gravel | 2 | 9 |
| Jaw Sand and Gravel LLC (bradford Pit) | Jaw Sand and Gravel LLC | Rock County, WI | Construction sand and gravel | 8 | 6 |
| Footville Rock & Lime Corp | Footville Rock & Lime Corp | Rock County, WI | Crushed, broken limestone | 1 | 4 |
| Graystone Wash Screen | Southern Wisconsin Aggregate Corporation | Rock County, WI | Sand, industrial | 1 | 3 |
| Portable Plant #5 | Bjoin Limestone Inc | Rock County, WI | Dimension limestone | 2 | 2 |
| Union Pit | Jaw Sand and Gravel LLC | Rock County, WI | Construction sand and gravel | 2 | 2 |
| Lippman-Hewitt Jaw | Southern Wisconsin Aggregate Corporation | Rock County, WI | Crushed, broken limestone | 2 | 2 |
| Corporate Contractors Inc., Quarry Div. | Corporate Contractors, Inc | Rock County, WI | Crushed, broken limestone | 2 | 1 |
| Little Limestone Inc. | Little Limestone Inc | Rock County, WI | Crushed, broken limestone | 1 | 0 |
US government work, public domain. Counts come from the MSHA files published on November 6, 2026. An open mine is one MSHA lists as Active, Intermittent, New Mine, Temporarily Idled or NonProducing; 13,673 were open that day. Citations, penalties, inspections and accident reports run from January 1, 2022. A citation is an inspector's allegation and an operator can contest it; the penalty is the amount MSHA first proposed, before any contest or settlement. An operator is the legal entity MSHA assesses, and a parent company is its controller. Mines run by sole proprietors or by individuals are counted in every total and are not named. This page uses MSHA data and is not endorsed or certified by MSHA. Free to reuse with credit to SpecStream under CC BY 4.0. Spot a wrong value? Write to [email protected] with the link to this page.