The Vasquez Boulevard and I-70 Superfund site sits in northeast Denver, Colorado, covering residential neighborhoods and former industrial land where two large smelting plants operated starting in the 1870s. Those plants refined gold, silver, copper, lead, and zinc, leaving heavy metals in soils and groundwater across the area. EPA added the site to the National Priorities List in 1999 and divided cleanup into three operable units targeting different areas.
Arsenic and lead are the two contaminants of concern. Both have been found in yard soils at levels that pose health risks to residents. Groundwater contamination from heavy metals is also present at the former smelter locations and is still being evaluated.
For the residential soils area, EPA sampled more than 4,500 properties between 2003 and 2006 and removed contaminated soil from about 800 yards where lead hit 400 parts per million or higher, or arsenic reached 70 parts per million or above. More than 91,000 cubic yards of contaminated soil were replaced with clean material. EPA partially deleted this operable unit from the National Priorities List in 2019. A 2024 five-year review deferred protectiveness findings because of new national guidance on lead screening levels, and the site team is now determining whether additional investigation is needed. About 60 properties where owners did not allow access still receive annual mailings about potential contamination. At the former Omaha and Grant Smelter site, the City and County of Denver completed excavation of contaminated materials between 2017 and 2018, and a combined investigation and feasibility study is currently underway. At the former Argo Smelter site, a removal action that started in April 2022 was completed in July 2024, and environmental investigations continue.
Across the full site, human exposure is not currently under control, contaminated groundwater is still migrating, and physical construction is not yet complete. EPA released updated lead guidance in October 2025 that changes soil screening levels, and the site team is evaluating how that affects future cleanup decisions here.
Community members can get involved in several ways. The Community Advisory Group meets monthly. EPA staff hold drop-in office hours at the Valdez-Perry Branch Library, with Spanish interpretation available, and no appointment is needed. Site records can be viewed at the Valdez-Perry Branch Library at 4690 Vine Street in Denver, the City and County of Denver Department of Environmental Health at 200 W. 14th Avenue, or the EPA Superfund Records Center at 1595 Wynkoop Street. To reach the EPA team directly or connect with the Community Advisory Group, contact Pedro Ayala or Becky Geyer using the information below.
