The Wyoming DEQ contacted EPA on September 9, 2019 to report beads of mercury on a city street near the intersection of West 5th Street and Thomes Avenue in Cheyenne, Wyoming.  The beads are spread over approximately 100 yards of the street, including an immediately adjacent to a storm drain.  The storm drain leads to Crow Creek. The local Fire Department closed down the impacted street. On September 9^th, EPA's response team deployed to the site to assist WDEQ and the local Fire Department and conduct further investigations. Work began at 0600 on September 10, 2019.

EPA's response team returned to the Site and found no indication that the mercury reached Crow Creek. After further investigation mercury appears to be caught in a sediment trap inside the storm drain. EPA analyzed mercury vapor levels and found high mercury vapor (up to 220,000 nanograms per cubic meter) under the storm drain cover and in the cracks of a gutter where is has accumulated. There is also visible mercury along a 75-yard section of the gutter and a sidewalk near both Union Hall and several residential properties. There is no immediate threat to the drinking water or to the public at this time. EPA is continuing to coordinate with Wyoming DEQ and the local fire department.

1. Vacuum visible mercury.

2. Investigate storm drain.

3. Sample water and sediment from Crow Creek.

4. Screen residential properties and Union Hall.

EPA's crew began vacuuming visible mercury in both the uphill and downhill directions along the street. EPA is also investigating the storm drain, sampling both sediment and water in Crow Creek and screening nearby residences and Union Hall.

EPA plans to:

- Complete removal of visible mercury from the sidewalk, street, gutters and storm drain.

- Finish screening nearby residences and Union Hall.

- Analyze sediment and water samples from Crow Creek.