2019-01318. National Oil and Hazardous Substances Pollution Contingency Plan; National Priorities List: Partial Deletion of the Vasquez Boulevard and I-70 Superfund Site

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule; notice of intent.

SUMMARY:

The Environmental Protection Agency (EPA) Region 8 is issuing a Notice of Intent to Delete Operable Unit 1 (OU1) of the Vasquez Boulevard and I-70 Superfund Site (Site) located in the City and County of Denver, CO, from the National Priorities List (NPL) and requests public comments on this proposed action. The NPL, promulgated pursuant to section 105 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended, is an appendix of the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). EPA and the State of Colorado (State), through the Colorado Department of Public Health and the Environment (CDPHE), have determined that all appropriate response actions under CERCLA, other than operation and maintenance and five-year reviews (FYR), have been completed. However, this deletion does not preclude future actions under Superfund.

This partial deletion pertains only to OU1, the residential portion of the Site. Operable Unit 2 (OU2) and Operable Unit 3 (OU3) will remain on the NPL and are not being considered for deletion as part of this proposed action.

DATES:

Comments must be received by March 8, 2019.

ADDRESSES:

Submit your comments, identified by Docket ID no. EPA-HQ-SFUND-1999-0010 by one of the following methods:

• https://www.regulations.gov. Follow on-line instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. EPA will generally not consider comments or comment contents located outside of the primary submission (i.e., on the web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit https://www.epa2.gov/​dockets/​commenting-epa-dockets.
• Email: [e-mail].
• Mail: Jesse Avilés, Remedial Project Manager, U.S. EPA, Region 8, Mail Code 8EPR-SR, 1595 Wynkoop Street, Denver, CO 80202-1129.

Instructions: Direct your comments to Docket ID no. EPA-HQ-SFUND-1999-0010. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at https://www.regulations.gov,, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through https://www.regulations.gov or email. The https://www.regulations.gov website is an “anonymous access” system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an email comment directly to EPA without going through https://www.regulations.gov,, your email address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses.

Docket: All documents in the docket are listed in the https://www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in https://www.regulations.gov or in hard copy at: U.S. Environmental Protection Agency, Region 8, 1595 Wynkoop Street, Denver, CO, [phone], Monday to Friday, 9:00 a.m. to 4:00 p.m., excluding Federal holidays.

FOR FURTHER INFORMATION CONTACT:

Jesse Avilés, Remedial Project Manager, U.S. Environmental Protection Agency, Region 8, EPR-SR, Denver, CO 80202, email: [e-mail].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Introduction

II. NPL Deletion Criteria

III. Deletion Procedures

IV. Basis for Intended Partial Site Deletion

I. Introduction

EPA announces its intent to delete OU1 of the Vasquez Boulevard and I-70 Superfund Site (Site) from the National Priorities List (NPL) and requests public comment on this proposed action. OU1 is the residential portion of the Site. The NPL constitutes Appendix B of 40 CFR part 300 which is the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), which EPA promulgated pursuant to section 105 of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) of 1980, as amended. EPA maintains the NPL as the list of sites that appear to present a significant risk to public health, welfare, or the environment. Sites on the NPL may be the subject of remedial actions financed by the Hazardous Substance Superfund (Fund). This partial deletion of OU1 of the Site is proposed in accordance with 40 CFR 300.425(e) and is consistent with the Notice of Policy Change: Partial Deletion of Sites Listed on the National Priorities List. 60 FR 55466 (Nov. 1, 1995). As described in section 300.425(e)(3) of the NCP, a portion of a site deleted from the NPL remains eligible for Fund-financed remedial action if future conditions warrant such actions.

EPA will accept comments on the proposal to partially delete this Site for thirty (30) days after publication of this document in the Federal Register.

Section II of this document explains the criteria for deleting sites from the NPL. Section III discusses procedures that EPA is using for this action. Section IV discusses the OU1 of the Site and demonstrates how it meets the deletion criteria.

II. NPL Deletion Criteria

The NCP establishes the criteria that EPA uses to delete sites from the NPL. In accordance with 40 CFR 300.425(e), sites may be deleted from the NPL where no further response is appropriate. In making such a determination pursuant to 40 CFR 300.425(e), EPA will consider, in consultation with the State, whether any of the following criteria has been met:

(1) Responsible parties or other persons have implemented all appropriate response actions required;

(2) All appropriate Fund-financed response under CERCLA has been implemented, and no further response action by responsible parties is appropriate; or

(3) The remedial investigation has shown that the release poses no significant threat to public health or the environment and, therefore, the taking of remedial measures in not appropriate.

Pursuant to CERCLA section 121(c) and the NCP, EPA conducts five-year reviews to ensure the continued protectiveness of remedial actions where hazardous substances, pollutants, or contaminants remain at a site above levels that allow for unlimited use and unrestricted exposure. EPA conducts such five-year reviews even if a site is deleted from the NPL. EPA may initiate further action to ensure continued protectiveness at a deleted site if new information becomes available that indicates it is appropriate. Whenever there is a significant release from a site deleted from the NPL, the deleted site may be restored to the NPL without application of the hazard ranking system.

III. Deletion Procedures

The following procedures apply to deletion of OU1 of the Vasquez Boulevard and I-70 Superfund Site:

(1) EPA consulted with the State before developing this Notice of Intent for Partial Deletion.

(2) EPA has provided the State 30 working days for review of this notice prior to publication of it today.

(3) In accordance with the criteria discussed above, EPA has determined that no further response is appropriate.

(4) The State of Colorado, through the CDPHE, has concurred with deletion of OU1 of the Site, from the NPL.

(5) Concurrently with the publication of this Notice of Intent for Partial Deletion in the Federal Register, a notice is being published in the Denver Post. The newspaper notice announces the 30-day public comment period concerning the Notice of Intent for Partial Deletion of the Site from the NPL.

(6) EPA placed copies of documents supporting the proposed partial deletion in the deletion docket, made these items available for public inspection, and copying at the Site information repositories identified above.

If comments are received within the 30-day comment period on this document, EPA will evaluate and respond to the comments before making a final decision to delete OU1. If necessary, EPA will prepare a Responsiveness Summary to address any significant public comments received. After the public comment period, if EPA determines it is still appropriate to delete OU1 of the Site, the Regional Administrator will publish a final Notice of Partial Deletion in the Federal Register. Public notices, public submissions and copies of the Responsiveness Summary, if prepared, will be made available to interested parties and included in the site information repositories listed above.

Deletion of a portion of a site from the NPL does not itself create, alter, or revoke any individual's rights or obligations. Deletion of a portion of a site from the NPL does not in any way alter EPA's right to take enforcement actions, as appropriate. The NPL is designed primarily for informational purposes and to assist EPA management. Section 300.425(e)(3) of the NCP states that the deletion of a site from the NPL does not preclude eligibility for future response actions, should future conditions warrant such actions.

IV. Basis for Intended Partial Site Deletion

The following information provides EPA's rationale for deleting the OU1 of the Vasquez Boulevard and I-70 Superfund Site from the NPL:

Site Background and History

The Vasquez Boulevard and I-70 Superfund Site (CO0002259588) covers approximately 4.5 square miles located in the north-central section of the City and County of Denver, Colorado. Historically, the Site and the area around the Site was a major smelting center for the Rocky Mountain West. The Omaha & Grant Smelter, the Argo Smelter, and the ASARCO Globe Smelter all previously operated in the area refining gold, silver, copper, lead, and zinc.

The Site was placed on the NPL in 1999 due to metal contamination associated with historical smelter operations. The proposed listing occurred on January 19, 1999 (64 FR 2950) and the final listing occurred on July 22, 1999 (64 FR 39878). The primary contaminants of concern are lead and arsenic. Subsequent investigations revealed that arsenic contamination might also be present as a result of application of lawn care products.

EPA divided the Site into Operable Units. OU1 is OU-Facility (Residential) Soils of Site. There are approximately 4,470 residential properties (most of which are single-family homes), 10 schools and 7 parks located in OU1. However, multifamily and commercial/industrial properties also exist in OU1. According to the 2010 census, approximately 16,262 people live within OU1, including approximately 2,700 children under the age of 6.

OU1 encompasses approximately four largely residential neighborhoods in north-central Denver: Swansea, Elyria, Clayton, and Cole. OU1 also includes the southwest portion of the Globeville neighborhood and the northern portion of the Curtis Park Neighborhood. These neighborhoods are located to the east of the former Argo Smelter (OU3) and the former Omaha and Grant Smelter (OU2), as well as the ASARCO Globe Smelter (AGS) Site. The AGS site is adjacent to OU1 and was addressed under a State consent decree with the ASARCO Multi-State trust and encompasses all of the Globeville neighborhood except the southwest portion of the neighborhood which was included in OU1 instead. The AGS site is currently addressed, since 2014, under an agreement with Globeville I, LLC.

OU2 is defined as the area where the former Omaha & Grant Smelter operated. OU2 is located between 42nd Avenue and St. Vincent Street, north of Brighton Boulevard and south of Interstate 70 and the existing Denver Coliseum, in Denver Colorado. OU3 is defined as the area where the former Argo Smelter operated and is bounded by 48th Avenue on the north, 46th Avenue on the south, Broadway Street on the east, and Huron Street on the west. Each operable unit has a unique physical location and historic operation. Thus, actions at one operable unit have been taken independently of actions at other portions of the Site. EPA has not selected remedies for OU2 and OU3, and the remedial investigations for these operable units are still in progress.

Remedial Investigation and Feasibility Study (RI/FS)

In 1997, CDPHE began a limited soil sampling program for OU1 in the Elyria and Swansea neighborhoods, located just east of the Globeville neighborhood, across the South Platte River. These results indicated that high concentrations of arsenic and lead in soil extended beyond the Globeville neighborhood. Accordingly, CDPHE requested EPA's assistance in immediately responding to the elevated levels of arsenic and lead in soil found in the Elyria and Swansea neighborhoods.

In 1998, EPA mobilized a team under its Emergency Response Program to conduct an extensive soil sampling effort and time-critical removal action for the houses in OU1 where soil concentrations posed immediate health risks to residents. The response action consisted of 3 phases. Phase I sampling occurred during March and April 1998. A minimum of 3 grab samples were collected from each property where EPA obtained access; 2 samples from the surface and 1 from the subsurface. EPA also collected soil samples from all schools and parks located within the initial study area. Samples were collected from locations judged to present a high potential for exposure relative to other areas of the property (for example, at bare spots within the yard) and were analyzed for arsenic, lead, cadmium, and zinc. From the Phase I data, EPA identified 37 properties as potentially requiring a time-critical removal action.

The Phase II sampling occurred in July and August 1998. Additional soil samples were collected from any residential properties that had a maximum surface soil concentration equal to or greater than 450 parts per million (ppm) for arsenic or 2,000 ppm for lead (i.e., time-critical removal action candidates). EPA's removal team revisited these residential properties and collected a 5-point composite sample from the front yard and a second 5-point composite sample from the backyard of each property. Arsenic and lead levels in these samples were measured, and any property with one or more composite samples exceeding the removal action levels for either arsenic or lead was identified for soil removal. In all, EPA sampled 1,393 properties as part of the Phase I and II programs. From the Phase II sampling results, EPA identified 143 properties as requiring a soil cleanup.

Based on the results of the Phase I and Phase II sampling programs, EPA determined that numerous residential properties within the Site contained concentrations of arsenic or lead at levels that could present unacceptable health risks to residents with long-term exposures. EPA placed the Site on the NPL on July 22, 1999 (64 FR 39878).

EPA began Phase III/RI activities in August 1998 while time-critical removal action activities were in progress. During the public comment period on the proposed NPL listing of the Site, the potentially responsible party, ASARCO, submitted information stating that the source of the arsenic in residential soil may be lawn care products that were readily available for residential use in the Rocky Mountain Region and elsewhere in the west in the 1950s and 1960s. These products were legally formulated with arsenic trioxide and lead arsenate to be effective in controlling crabgrass. ASARCO specifically identified PAX 3-year Crabgrass Control, available from the 1950s until the early 1970s. The product is no longer available commercially. Also, efforts began to investigate the source of the arsenic and lead in residential soils. Toward that end, EPA used its CERCLA section 104(e) information gathering authority to acquire a 6-ounce sample of the PAX 3-year Crabgrass Control product from Martin Resources, a company that acquired the company that had manufactured PAX. Tests on the PAX sample formulation provided by Martin Resources were helpful to EPA, but by themselves proved inconclusive to determine whether all arsenic and lead found in the VB/I-70 residential soils derived from pesticides or smelter emissions, or both.

To assess ASARCO's concerns, EPA's Phase III/RI activities focused on collecting necessary information to accurately characterize exposure and risk to residents at the Site to support a quantitative baseline human health risk assessment and remedial risk management decisions. EPA Phase III concluded remedial investigation activities in November 2000. This sampling program supported the physio-chemical characterization of soils, the baseline human health risk assessment, and soil sampling of additional properties. During Phase III, 3,007 properties were sampled, including the re-sampling of properties sampled during Phases I and II. As part of the Phase III remedial investigation, sampling was conducted at discreet soil depths to evaluate where the highest soil concentrations occurred. The evaluation determined that soil concentrations were highest in the uppermost 2 inches of the soil profile, and supported soil removal down to a 1-foot depth limit. Based on the phase III data, 30 additional properties were identified for time-critical soil removal.

Response Actions

Soil removals in residential yards began with the time-critical removal action in 1998, continued with the subsequent non-time-critical removal action in 2003, then the remedial action began in 2004. In September 1998, EPA issued an Action Memorandum that established the basis for conducting a time-critical removal action. The Action Memorandum required that soil be removed and replaced at any property with an average arsenic soil concentration greater than 450 ppm and/or lead soil concentration greater than 2000 ppm. These removal “action levels” were chosen to protect young children from adverse health effects related to short-term (sub-chronic) exposure. EPA conducted soil removals at 18 properties in October and November of 1998.

On March 6, 2003, EPA issued an Action Memorandum that established the basis for conducting a non-time-critical removal action. The Action Memorandum required the removal and replacement of soil at any property that had an arsenic soil level greater than 240 ppm and/or lead soil levels greater than 540 ppm. These “action levels” were determined from the baseline risk assessment to address the properties that presented the highest risk of adverse health effects to children and adult residents. From the Phase III sampling results, EPA identified 143 properties as requiring a soil cleanup, and in 2003, EPA conducted cleanups at 133 of these properties. The properties not addressed by this non-time-critical removal action were included in the list of properties to be addressed by the remedial action under the OU1 record of decision (ROD).

Selected Remedy

EPA and CDPHE signed the ROD (2003 OU1 ROD) detailing the final remedy for OU1 on September 25, 2003. The selected remedy for OU1 consisted of 3 components to address lead and arsenic contamination in residential soils: Soil sampling, soil removal, and a community health program. Additionally, the 2003 OU1 ROD provided an informational institutional control through the community health program. The community health program ended in 2008. An explanation of significant differences (2014 ESD) modifying the selected remedy for OU1 was signed on September 30, 2014. The 2014 ESD added institutional controls for the residential properties where EPA was unable to secure access for sampling and/or soil removal.

As identified in the 2003 OU1 ROD, the remedial action objectives (RAOs) for arsenic in soil are:

• For all residents of the Site, prevent exposure to soil containing arsenic in levels predicted to result in an excess lifetime cancer risk associated with ingestion of soil which exceeds 1 × 10⁻⁴, using reasonable maximum exposure assumptions.
• For all residents of the Site, prevent exposure to soil containing arsenic in levels predicted to result in a chronic or sub-chronic hazard quotient (HQ) associated with ingestion of soil that exceeds a HQ of 1, using reasonable maximum exposure assumptions.
• For children with soil pica behavior who reside in the Site, reduce the potential for exposures to arsenic in soil that result in acute effects.

The RAOs for lead in soil are:

• Limit exposure to lead in soil such that no more than 5 percent of young children (72 months or younger) who live within the Site are at risk for blood lead levels higher than 10 micrograms per deciliter (μg/dL) from such exposure. This provides 95% confidence that children exposed to lead in soil will be protected.

In 2016, EPA published a memorandum titled “Updated Scientific Considerations for Lead in Soils Cleanups.” A recent EPA review, which included review of the 2016 memorandum, concluded that the cleanup level for lead in OU1 remains appropriate.

The 2003 OU1 ROD adjusted the action levels identified for conducting the non-time-critical removal actions from 240 ppm to 70 ppm for arsenic and from 540 ppm to 400 ppm for lead. This change was based on results of public comment on the initial Proposed Plan, which suggested that the cleanup levels for OU1 should be the same as those adopted by the State of Colorado for the Asarco Globe Smelter Site. The adjusted ROD action levels were within the range of preliminary remediation goals identified in the Feasibility Study Report based on results of the Baseline Risk Assessment.

The major portions of the remedy were implemented from 2003 through 2006 with a few residential properties being remediated in 2008 and, as explained below, a few more residential properties were remediated between 2012 and 2015. In the summer of 2013, a last call letter was sent to owners of properties not previously sampled. In the period from 1999 to 2015, 4,445 properties were sampled with 814 properties being remediated. Soil removals occurred at properties that had arsenic soil concentrations greater than 70 ppm or that had lead soil concentrations greater than 400 ppm consistent with the 2003 OU1 ROD. For properties where soil removal was conducted, all accessible soils were removed to a depth of 12 inches. Since the contamination was only found in the top 3-6 inches, EPA considered excavation to 12 inches to be adequate for removing all lead and arsenic contamination in the soils. The excavated areas were backfilled with clean soil, and pre-remediation yard features were restored to the extent practicable, in consultation with the property owner. At the homeowner's request, flower beds and vegetable gardens were sampled individually. If the concentrations of lead and arsenic in the flower beds or vegetable gardens were found to be below the action levels, then soil removal was not required in these areas. This was the only situation where a partial soil removal occurred at a property. If sprinkler systems were present, the system was removed and reinstalled.

During the 2003 through 2008 period, all excavated soils were transported to the ASARCO Globe Plant where they were used as capping and fill material in implementing the selected remedy at the ASARCO Globe Plant Site. The ASARCO Globe Plant Site is managed by CDPHE under a program similar to Superfund. The remedy at that site included managing the soils from OU1 at the onsite repository. The repository was later capped.

EPA considered the construction phase of the OU1 remedy complete in 2008. The Remedial Action Report Addendum that covered soil sampling and removal activities as part of the remedial action was produced in August 2008. However, as part of the “last call effort,” more sampling and residential cleanups were performed between 2012 and 2015; a final Remedial Action Report was signed on February 22, 2017 to include this work. Maps of the operable unit boundaries and information on the cleanup activities can be found in this report.

The community health program was developed to raise awareness in the community about lead and arsenic hazards and was designed to complement the soil cleanups. The community health program was a unique program designed by local, federal and state government representatives and community leaders. It was developed in consultation with an advisory stakeholder group for the Site and implemented by the City and County of Denver. Funded by EPA and the State, the City and County of Denver administered the program, which included door-to-door visits from community members trained to provide education to area residents on the hazards of lead, arsenic and other environmentally-related topics. The program provided opportunities for parents to have their children tested for lead or arsenic exposure. The community health program consisted of two activities, providing biomonitoring services for children and conducting community outreach.

Biomonitoring: The primary goal of the biomonitoring program was to test young children and pregnant women to determine if they had been exposed to lead and/or arsenic. This was accomplished through the following tasks:

• Establishing and staffing periodic testing clinics in each neighborhood
• Collection and analysis of biomonitoring samples
• Reporting results to each participant
• Recommendations to parents for environmental and medical follow-up actions, if needed.

Thirty-eight clinics were held between November 2004 and October 2006. During this time, 661 individuals participated in the biomonitoring program. Health officials identified twenty children with elevated blood lead above 10 µg/dL, and 94 children were identified with elevated blood lead concentrations; i.e., concentrations ranging from 5-10 µg/dL. The 10 µg/dL value was adopted from EPA's OSWER Directive 9355.4-12, July 14, 1994, which determined that, in Superfund site cleanups, EPA will attempt to limit exposure to soil lead levels such that a typical (or hypothetical) child or group of similarly exposed children would have an estimated risk of no more than 5% of exceeding a blood lead level of 10 µg/dL. The parents of children found with elevated blood lead concentrations were referred to organizations that were able to follow-up with the family on environmental and medical issues.

In addition, in accordance with the Community Health Program requirements in the ROD for lead, exterior lead-based paint assessments were conducted at all properties where soil was removed due to elevated lead concentrations. A total of 297 properties met the criteria for lead-based paint assessments. During the assessment, all structures including garages, fences, and sheds with chipping and peeling paint were tested for lead-based paint. If EPA determined that there was peeling lead-based paint on the property sufficient to cause recontamination of the soil above the action level, then EPA performed an exterior lead-based paint abatement at the property. As a result of the assessments conducted, 120 homes received exterior lead-based paint abatements. This work was performed in accordance with the Colorado “Regulation No. 19, Lead-Based Paint Abatement.”

Community Outreach: The City and County of Denver conducted community outreach using a door-to-door canvassing outreach model, utilizing community health workers to provide individual health education. The community health workers were members of the Site's community that the City and County of Denver trained to provide health information concerning lead and arsenic exposure. The community health workers provided information on the following:

• Health effects of lead
• Health effects of arsenic
• Soil pica behavior
• Soil sampling and soil removal aspects of the remedy
• Biomonitoring program.

Community health workers conducted home visits at 94% of the homes within the site boundaries. In addition to home visits, outreach was conducted to realtors and contractors that live or work within the site communities by mailing them relevant information. The community health program concluded in 2008 with completion of the soil sampling and soil removal components of the OU1 remedy.

Operation and Maintenance

Operation and maintenance activities are required for the institutional controls provided in the 2014 ESD. O&M activities include monitoring the ICs, reviewing property records for the properties that have either a recorded Notice of Potential Environmental Conditions or a recorded Notice of Environmental Conditions and preparing and mailing the annual informational letter. CDPHE sends the annual letters to the properties with a Notice of Environmental Conditions and works with the property owners that want to remove the notice of environmental conditions.

Institutional controls were implemented in the summer of 2014 for 69 residential properties within OU1 where the property owner denied EPA access to sample and/or remove soil. The ICs were incorporated into the OU1 remedy through the issuance of the 2014 ESD. The IC for OU1 is an informational IC consisting of 2 parts. The first part is either a Notice of Potential Environmental Conditions, for residential properties where EPA did not sample, or a Notice of Environmental Conditions for properties where EPA has sampling results showing lead or arsenic levels above the action levels established in the ROD but where cleanup was not conducted. These notices were filed with the City and County of Denver Clerk and Recorders Office in the title records and serve to notify present, prospective, and future owners of the potential for elevated levels of lead or arsenic in the properties' soils.

The second part of the informational IC for OU1 is an informational letter that is sent annually to the owner of record and to the property address to make sure that any tenants are informed. This annual informational letter provides the specific information EPA has on the property and provides information on how to minimize exposure to potentially contaminated soil. ICs were implemented in June 2014, when EPA filed either a Notice of Environmental Conditions or a Notice of Potential Environmental Conditions in each properties' title file at the City and County of Denver Clerk and Recorder's Officer for 69 unaddressed properties. A copy of the filed notice was sent to the property owner of record. Since January 2015, annual informational letters are sent to each owner as well as to the property address.

Five-Year Review

Statutory Five-Year Reviews (FYRs) of the Site are required because hazardous substances remain on-Site above levels which allow for unlimited use and unrestricted exposure. The last FYR Report was signed on September 30, 2014 and found that the remedy implemented at OU1 of the Site is protective of human health and the environment. The 2014 FYR did not identify any issues or make any recommendations.

The next FYR is scheduled to be completed by September 2019. FYRs will continue every 5 years thereafter.

Community Involvement

Due to the high degree of public interest, the large population impacted by OU1, and the cultural differences among the OU1 neighborhoods, EPA and CDPHE expanded community involvement to provide for extensive public input throughout the remedial process. Expanded public involvement included conducting a stakeholder assessment, establishment of a stakeholders working group, providing funding for a technical assistance grant, and additional public meetings and fact sheet mailings. All materials were provided in both Spanish and English and all meetings were conducted with Spanish translation services. In August 1998, EPA formed a Working Group of stakeholders to provide an open forum for discussing all technical aspects of EPA's RI/FS, risk assessment, ROD remedial design and remedial action. The Working Group addressed the Environmental Justice concern of having the community participate in decision making by providing direct access to decision makers. Through the Working Group, data and issues were discussed, allowing for community input into decision-making throughout the Superfund process.

The stakeholders attending the Working Group meetings included representatives from all parties that had an interest in OU1. The Working Group included representatives of the City and County of Denver; CDPHE; the Agency for Toxic Substances and Disease Registry (ATSDR); ASARCO; and representatives from the four Denver neighborhoods included in OU1. Stakeholders also included the Clayton, Elyria, and Swansea Environmental Coalition (CEASE), the recipient of a Technical Assistance Grant from EPA.

During the period 2012 to 2014, EPA made a concerted effort through letters, phone calls and neighborhood canvasing to reach the owners of the unaddressed properties to offer them the opportunity to have their properties sampled and/or cleaned up. More recently, a community advisory group formed to discuss response activities at OU2.

Determination That the Site Meets the Criteria for Deletion

In accordance with the NCP at 40 CFR 300.425(e), EPA has determined that the response activities at OU1 are complete and the operable unit poses no unacceptable risk to human health or the environment. EPA also has determined that the implemented remedies achieve the degree of cleanup and protection specified in the 2003 OU1 ROD and the 2014 ESD. Moreover, EPA has determined that all selected removal and remedial action objectives and associated cleanup goals for OU1 are consistent with agency policy and guidance. Therefore, EPA has determined that no further response is necessary at OU1. EPA consulted with and has the concurrence of the State of Colorado on this partial deletion action.

As such, this partial deletion meets the deletion requirements as specified in the National Contingency Plan at 40 CFR 300.425(e) and is consistent with the Notice of Policy Change: Partial Deletion of Sites Listed on the National Priorities List (60 FR 55466 (Nov. 1, 1995) and OSWER Directive 9320.2-22, Close Out Procedures for National Priority List Sites.

List of Subjects in 40 CFR Part 300

• Environmental protection
• Air pollution control
• Chemicals
• Hazardous waste
• Hazardous substances
• Intergovernmental relations
• Penalties
• Reporting and recordkeeping requirements
• Superfund
• Water pollution control
• Water supply

Authority: 33 U.S.C. 1321(d), 42 U.S.C. 9601-9657; E.O. 12580, E.O. 12777, E.O. 13626, 52 FR 29233, 56 FR 54757, 77 FR 56749, 3 CFR 2013 Comp., p. 306; 3 CFR, 1991 Comp., p. 351; 3 CFR, 1987 Comp., p. 193.

Dated: December 20, 2018.

Douglas H. Benevento,

Regional Administrator, Region 8.