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The Colorado Smelter was a silver and lead smelter that operated in the Eilers and Bessemer neighborhoods from 1883 to 1908. EPA listed the site on the National Priorities List in December 2014, due to its concern about high levels of arsenic and lead (metals) that had been identified in smelter slag and neighborhood soils.

Pueblo was once home to five ore smelters and is still home to one active steel mill. The Colorado Smelter historical footprint is bound by Santa Fe Avenue to the east, Mesa Avenue to the south, Interstate 25 to the west, and the Arkansas River to the north. The Bessemer, Eiler and Grove neighborhoods are adjacent to the former Colorado Smelter site, which now consists of building remains and an approximately 700,000-square-foot slag (waste) pile.

The potential for contamination at the Colorado Smelter site was discovered during an earlier inspection of the Santa Fe Bridge Culvert site, which began a series of investigations in the early 1990s and continues today. In 2010, CDPHE conducted a focused site inspection of properties surrounding the Colorado Smelter; this study determined the presence of elevated lead and arsenic levels. These levels pose a threat to current and future residents. Additional sampling will help determine the type and scope of cleanup activities.

There are approximately 1,900 residential parcels in the preliminary study area, which covers a half-mile radius from the smokestack of the former smelter. Ninety-five percent of the homes are pre-1978 (before the lead paint ban). They are predominantly single-family detached homes, many with bare-soil yards.

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What Is Being Done to Clean Up the Site?

EPA has started the Remedial Investigation/Feasibility Study RI/FS and has divided the site into two operable units (OUs), OU1 (Community Properties) and OU2 (Former Smelter Area).

Colorado Smelter site base map showing former smelter location, slag pile, outlines of operable units 1 and 2 of the Superfund site, and streets.

The RI/FS phase of the Superfund process determines the nature and extent of contamination at a site, tests whether certain technologies are capable of treating the contamination, and evaluates the cost and performance of technologies that could be used to clean up the site.

EPA and Colorado Department of Public Health and Environment (CDPHE) signed the interim Record of Decision (i-ROD) for the residential properties portion of OU1 “Community Properties” on September 26, 2017 after the close of the second public comment period on September 15, 2017. The i-ROD documents EPA’s cleanup plans for residential properties, specifically the removal and replacement of soils up to 18 inches below ground surface, as well as indoor dust cleanups, where necessary. EPA completed 27 indoor cleanups under an emergency removal action; seven additional indoor cleanups were completed in December 2017 under the remedial program as outlined in the i-ROD.

The overall capital construction project cleanup cost is estimated at $43,828,600 and is anticipated to address approximately 817 properties.

The site-specific residential cleanup levels that are part of this i-ROD are measured in parts per million (ppm) and are:

  • Arsenic in soil – 61 ppm
  • Lead in soil – 350 ppm
  • Arsenic in indoor dust – 61 ppm
  • Lead in indoor dust – 275 ppm

The site-specific risk-based cleanup levels listed above are considered protective of human health. The lead level is based on the Integrated Exposure Uptake Biokinetic (IEUBK) model and other site-specific information which predicts the level of lead in a child’s blood in specific environments. Using the IEUBK model and site-specific exposure parameters, the predicted blood lead level to be associated with 350 ppm lead in soil is 6.0 μg/dL. The soil lead cleanup level of 350 ppm is intended for comparison to area-weighted average results for each property and comports with guidance in the EPA Superfund Lead-Contaminated Residential Sites Handbook.

The site-specific arsenic level is protective and conservative since it is well below 120 ppm, which is the cancer risk of approximately one additional instance of cancer in 10,000 people. This level is also consistent with EPA regulation in the National Contingency Plan (NCP), which establishes an acceptable risk range of 10-4 to 10-6, or a range of one excess cancer in 10,000 cases to one excess cancer in 1,000,000 cases. The arsenic cleanup level is consistent and in the range of cleanup levels that have occurred in Colorado.

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What Is the Current Site Status?

EPA, CDPHE and the Pueblo City-County Health Department (PCCHD) work collaboratively to investigate the nature and extent of contamination, identify potential clean up solutions at the site, and conduct health education and outreach to community members in the site study area.

Soil and dust sampling at residential properties helps EPA know whether or not a property is contaminated with lead, arsenic or other heavy metals. Residential sampling began in 2015 and EPA continues to sample indoor lead dust and outdoor soil as part of ongoing site activities. The county-owned property, Runyon Field, will be sampled in 2018.

Under the i-ROD, indoor cleanups will continue and outdoor cleanups can begin. Properties that received an indoor cleanup under the emergency removal will be the first yards to be addressed in 2018. As properties get sampled, final results letters go out to owners documenting whether or not a cleanup is needed.

At Operable Unit 2 (OU2 – the Former Smelter Area), EPA is in the early stages of data collection. Planning is taking place to identify locations for air monitors, obtain property access and review air data from any existing monitors. Other types of samples, such as slag/waste, surface and subsurface soil, surface water, sediment, and ground water will be collected in order to characterize OU2 and further understand the nature and extent of site contamination.

EPA, CDPHE and PCCHD also work with the public to educate individuals and their families on steps they can take to protect themselves from exposure to potential site contaminants. Agencies attend community events, respond to questions and provide education at the Community Advisory Group monthly meetings. The PCCHD lead program, funded through an EPA grant and supplemented by CDPHE, helps people get blood lead testing and healthy home screenings at no cost for those living within the Superfund preliminary study area and at low cost to Pueblo residents outside the study area. The PCCDD lead program also provides educational material and risk reduction material (cleaning supplies) to residents of the site.

Together, site activities and collaborative efforts such as sampling, cleanups and education are helping to reduce human exposure to site contaminants.

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Sampling and Monitoring

In 2015, EPA collected soil samples from 12 properties within operable unit 1 (OU1) of the site preliminary study area to examine different sampling and analytical methods. The purpose of sampling was to collect information necessary to make sure an accurate and efficient investigation will take place during the site remedial investigation (RI) and to help inform the OU1 RI Quality Assurance Project Plan (QAPP).

The QAPP, along with any amendments, explains the sampling and analytical procedures for the site. This ensures that any EPA team or contractor will use the same methods to collect data in order to produce good quality results. Under the OU1 RI QAPP, EPA samples indoor dust and outdoor soils for arsenic, lead and other metals.

As of February 16, 2018, EPA completed the following sampling activities:

  • 363 homes sampled indoors for lead dust and other metals.
  • 684 homes sampled outdoors for lead and other metals in soil
  • 34 total cleanups of lead-contaminated interior dust. Twenty-seven emergency indoor dust cleanups (June 2016 – July 2017) and seven additional priority indoor cleanups (December 2017).
  • 4 parks’ soils sampled - Bessemer, Benedict, & Stauter Field, Bessemer School Park
  • 85 unpaved city alleys sampled within the study area
  • 2 vacant city parcels sampled
  • Bessemer Academy School sampling

EPA is conducting a duct work pilot study. Community Advisory Group members raised concerns about possible recontamination by duct work systems after a cleanup takes place. Existing research is limited. The duct work pilot study looks at the effectiveness of reducing lead exposure by cleaning indoor duct work. Phase I pilot study was completed in April 2017; however, there was not enough data to provide meaningful information or statistically analyze the results. Phase II is in progress and results of the study are expected in the summer of 2018.

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Emergency Response and Removal

In 2014, EPA performed a removal action that included putting up no trespassing and caution signs around OU2, the Former Smelter Area. The signs were created with input by the community and local partners to raise awareness about the presence of heavy metals in OU2 and warn people about the potential health risk from walking through that area.

No-trespassing and caution signs around OU2, the Former Smelter Area

No-trespassing and caution signs around OU2, the Former Smelter Area

In 2016 and 2017, EPA began to address homes with high levels of lead dust inside the homes. During December 2017, EPA completed a time-critical removal action at Benedict Park to cleanup arsenic contamination found a foot or more beneath the eastern play area. EPA determined that it is best to remove soil from this area to ensure long-term protection from future erosion or upward movement of contaminated soils during freeze-thaw cycles.

Read more about the removal work at EPA’s On-Scene Coordinator Response website »

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Enforcement Information

Along with other Pueblo smelters, the Colorado Smelting Company merged with ASARCO in 1899. ASARCO last operated the Colorado Smelter in 1908. After the smelter facility was damaged in the Pueblo Flood of 1921, ASARCO conveyed the property to the Newton Lumber Company. The lumber company operated the site as a lumber yard into the 1960s. After Newton Lumber Company ownership, the facility property was sold to a number of individuals and small to medium sized companies. Some ASARCO facility slag material was used as track ballast for the D&RG track constructed between Florence and Cañon City; and, in 1923, bricks from the blast furnace smoke stack were used to construct St. Mary School. ASARCO has since become bankrupt and, to date, EPA has not identified other viable responsible parties.

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