National Oil and Hazardous Substance Pollution Contingency Plan; National Priorities List; Partial Deletion of the Denver Radium Superfund Site, 54779-54789 [2010-22489]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 75, Number 174 (Thursday, September 9, 2010)]
[Rules and Regulations]
[Pages 54779-54789]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-22489]


-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 300

[EPA-HQ-SFUND-1983-0002; FRL-9198-6]


National Oil and Hazardous Substance Pollution Contingency Plan; 
National Priorities List; Partial Deletion of the Denver Radium 
Superfund Site

AGENCY: Environmental Protection Agency.

ACTION: Direct final rule.

-----------------------------------------------------------------------

SUMMARY: The Environmental Protection Agency (EPA) Region 8 is 
publishing a direct final Notice of Partial Deletion of

[[Page 54780]]

the Denver Radium Superfund Site (Site). Specifically, EPA intends to 
delete from the National Priorities List (NPL) each of the 11 operable 
units at the Denver Radium Site, located in the City and County of 
Denver, Colorado. Groundwater contamination associated with Operable 
Unit 8 will remain on the NPL. 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). 
This direct final partial deletion is being published by EPA with the 
concurrence of the State of Colorado, through the Colorado Department 
of Public Health and Environment, because EPA has determined that all 
appropriate response actions at these identified parcels under CERCLA, 
other than operation, maintenance, and five-year reviews, have been 
completed. However, this partial deletion does not preclude future 
actions under Superfund.
    This partial deletion pertains to each of the 11 operable units of 
the Denver Radium Superfund Site. Groundwater contamination associated 
with Operable Unit 8 will remain on the NPL and is not being considered 
for deletion as part of this action.

DATES: This direct final rule is effective November 8, 2010 unless EPA 
receives adverse comments by October 12, 2010. If adverse comments are 
received, EPA will publish a timely withdrawal of the direct final 
partial deletion in the Federal Register informing the public that the 
partial deletion will not take effect.

ADDRESSES: Submit your comments, identified by Docket ID no. EPA-HQ-
SFUND-1983-0002, by one of the following methods:
     https://www.regulations.gov. Follow on-line instructions 
for submitting comments.
     E-mail: dalton.john@epa.gov.
     Fax: (303) 312-7110 (Attention: John Dalton, Public 
Affairs and Involvement)
     Mail: John Dalton, Public Affairs and Involvement (8OCPI), 
U.S. EPA Region 8, 1595 Wynkoop Street, Denver, CO 80202-1129, (303) 
312-6633.
     Hand Delivery: U.S. EPA Region 8, 1595 Wynkoop Street, 
Denver, CO. Such deliveries are only accepted during the Docket's 
normal hours of operation, and special arrangements should be made for 
deliveries of boxed information.
    Instructions: Direct your comments to Docket ID no. EPA-HQ-SFUND-
1983-0002. 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 e-mail. The https://www.regulations.gov Web site 
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 e-mail comment directly to EPA without 
going through https://www.regulations.gov, your e-mail 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 the 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 Records Center, 1595 
Wynkoop Street, Denver, CO 80202, Hours: M-F, 8 a.m. to 4 p.m.
Colorado Department of Public Health and Environment, 4300 Cherry Creek 
Drive South, Denver, CO 80246, Hours: M-F, 8 a.m. to 5 p.m.

FOR FURTHER INFORMATION CONTACT: Rebecca Thomas, Project Manager (8EPR-
SR), U.S. Environmental Protection Agency Region 8, EPR-SR, 1595 
Wynkoop Street, Denver, CO 80202-1129, (303) 312-6552, 
thomas.rebecca@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Introduction
II. NPL Deletion Criteria
III. Partial Deletion Procedures
IV. Basis for Site Partial Deletion
V. Partial Deletion Action

I. Introduction

    EPA Region 8 is publishing this direct final Notice of Partial 
Deletion for the Denver Radium Superfund Site (Site) from the National 
Priorities List (NPL). This partial deletion pertains to each of the 11 
operable units of the Denver Radium Superfund Site, with the exception 
of groundwater contamination associated with Operable Unit 8. The NPL 
constitutes Appendix B of 40 CFR part 300, which is the 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 the 
Denver Radium Superfund 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.
    Because EPA considers this action to be non-controversial and 
routine, this action will be effective November 8, 2010 unless EPA 
receives adverse comments by October 12, 2010. Along with this direct 
final Notice of Partial Deletion, EPA is co-publishing a Notice of 
Intent for Partial Deletion in the ``Proposed Rules'' section of the 
Federal Register. If adverse comments are received within the 30-day 
public comment period on this partial deletion action, EPA will publish 
a timely withdrawal of this direct final Notice of Partial Deletion 
before the effective date of the partial deletion, and the partial 
deletion will not take effect. EPA will, as appropriate, prepare a 
response to comments and continue with the deletion process on the 
basis of the Notice of Intent for Partial Deletion and the comments 
already received. There will be no additional opportunity to comment.

[[Page 54781]]

    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 Denver Radium Superfund Site 
and demonstrates how portions of the Site proposed for deletion meet 
the deletion criteria. Section V discusses EPA's action to partially 
delete the Site from the NPL unless adverse comments are received 
during the public comment period.

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 have 
been met:
    i. Responsible parties or other persons have implemented all 
appropriate response actions required;
    ii. All appropriate Fund-financed response under CERCLA has been 
implemented, and no further response action by responsible parties is 
appropriate; or
    iii. 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 is 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. Partial Deletion Procedures

    The following procedures apply to partial deletion of the 11 
operable units of the Site:
    (1) EPA consulted with the State of Colorado prior to developing 
this direct final Notice of Partial Deletion and the Notice of Intent 
for Partial Deletion co-published in the ``Proposed Rules'' section of 
the Federal Register.
    (2) EPA has provided the State 30 working days for review of this 
notice and the parallel Notice of Intent for Partial Deletion prior to 
their publication today, and the State, through the Colorado Department 
of Public Health and Environment, has concurred on the partial deletion 
of the Site from the NPL.
    (3) Concurrently with the publication of this direct final Notice 
of Partial Deletion, a notice of the availability of the parallel 
Notice of Intent for Partial Delete is being published in a major local 
newspaper, 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.
    (4) The EPA placed copies of documents supporting the partial 
deletion in the deletion docket and made these items available for 
public inspection and copying at the Site information repositories 
identified above.
    (5) If adverse comments are received within the 30-day public 
comment period on this partial deletion action, EPA will publish a 
timely notice of withdrawal of this direct final Notice of Partial 
Deletion before its effective date and will prepare a response to 
comments and continue with the deletion process on the basis of the 
Notice of Intent for Partial Deletion and the comments already 
received.
    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 Partial Site Deletion

    The following information provides EPA's rationale for deleting 
from the NPL each of the 11 operable units of the Denver Radium Site, 
with the exception of groundwater contamination associated with 
Operable Unit 8:

Site Location

    The Denver Radium Superfund Site (EPA ID: COD980716955), located in 
Denver, Colorado, consists of more than 40 contaminated properties. 
These properties have been grouped into 11 operable units which, except 
for groundwater contamination associated with OU 8, are proposed for 
deletion from the NPL. At certain locations, marked with an asterisk, 
waste has been left in place. These locations will require continued 
operation and maintenance to inspect the integrity of the cap and 
ensure institutional controls (ICs) are functioning properly. The Site 
was added to the Superfund NPL in 1983 (48 FR 40658, September 8, 
1983).

------------------------------------------------------------------------
           OU                 Property name               Address
------------------------------------------------------------------------
OU1....................  B & C Metals (now        1623-1625 West 12th
                          Martin Shea Millworks).  Ave.
OU1....................  Erickson Monuments.....  1241-1245 Quivas St.
OU1....................  Materials Handling, Inc  1740 West 13th Ave.
OU1....................  Rudd...................  1223-1229 Quivas St.
OU1....................  City/County of Denver    East of B & C Metals,
                          Alley/Driveway.          between 12th Ave. and
                                                   Erickson Monuments.
OU2*...................  DuWald Steel (now Atlas  1100 Umatilla Street.
                          Metals & Iron).
OU2....................  Rocky Mountain Research  1020-1030 Yuma Street.
                          Corporation (now A1
                          Transmission and
                          Nationwide Courier).
OU2....................  G&K Services...........  999 Vallejo Street.
OU2....................  Jenkins Property.......  2191 West 10th Street.
OU2....................  Staab Property.........  2121 West 10th Street.
OU2....................  Air Conditioning, Inc..  1001 South Tejon
                                                   Street.
OU2*...................  Burlington Northern      Between 10th & 11th
                          Railroad.                Avenues.
OU2....................  Colorado DOT--Jerome     2300 West 11th Avenue.
                          Maintenance Yard.
OU2....................  Flame Spray, Inc.......  1900 West 12th Avenue.
OU2....................  Alpha Omega Electronics  1010 Yuma Street.
OU2....................  Capital Management       1050 Yuma Street.
                          Realty (now Royal
                          Textile).
OU2....................  Denver Water Board.....  1600 West 12th Avenue.

[[Page 54782]]

 
OU3....................  Creative Illumination,   1298 South Kalamath
                          Inc.                     Street.
OU3*...................  Packaging Corporation    1377 South Jason
                          of America (PCA) (now    Street.
                          Caraustar Custom
                          Packaging).
OU3....................  GT Car Shop/Aspen        1235 South Jason
                          Design and               Street.
                          Manufacturing.
OU3*...................  Denver right-of-way....  1377 S. Jason Street.
OU3....................  Kwan Sang Noodle         1140 West Louisiana.
                          Company, formerly
                          Titan Labels.
OU3....................  Various tenants........  1300 South Jason
                                                   Street.
OU3*...................  Central & Sierra         Between W. Louisiana &
                          Railroad.                W. Florida Streets.
OU4*...................  Robinson Brick and Tile  500 South Santa Fe
                          Company (ROBCO) (now     Drive.
                          Home Depot).
OU5....................  Denver and Rio Grande    Immediately East of
                          Western Railroad ROW.    OU4.
OU6....................  Alley in City and        Between Mariposa and
                          County of Denver right-  Lipan Streets and
                          of-way.                  between 5th and 6th
                                                   Avenues.
OU6....................  Allied (General          1271 West Bayaud
                          Chemical).               Avenue.
OU6....................  Brannan Sand and Gravel  61st Ave. and Clear
                                                   Creek.
OU6....................  Central and Sierra       2301 15th Street.
                          Railroad right-of-way/
                          Centennial Tire.
OU6....................  Denver Water Department  1190 Yuma Street.
OU6....................  Public Service Company.  South Pecos St. & West
                                                   Arizona Ave.
OU6....................  Ruby Hill Park.........  Jewell St. and S.
                                                   Platte River Drive.
OU6....................  Environmental Metals,    1155 West 5th Avenue.
                          Inc. (bldg has been
                          razed).
OU7....................  9th Ave.: Ogden St. to   N/A.
                          Cheesman Pk.
OU7....................  11th Ave.: Josephine     N/A.
                          St. to Cheesman Pk.
OU7....................  23rd St.: California     N/A.
                          St. to Lawrence St.
OU7....................  Corona: 7th Ave. to      N/A.
                          10th Ave.
OU7....................  Downing St .: 7th Ave.   N/A.
                          to 10th Ave.
OU7....................  Humboldt St.: 7th Ave.   N/A.
                          to 9th Ave.
OU7....................  Lafayette St.: 1st Ave.  N/A.
                          to 10th Ave.
OU7....................  Marion St.: 6th Ave. to  N/A.
                          10th Ave.
OU7....................  York St.: 6th Ave. to    N/A.
                          13th Ave.
OU8....................  S.W. Shattuck Chemical   1805 South Bannock
                          Company (soil).          Street.
OU8*...................  S.W. Shattuck Chemical   1805 South Bannock
                          Company (groundwater).   Street.
OU9A...................  International House of   2001, 2015, and 2017
                          Pancakes and Larry's     East Colfax Avenue.
                          Trading Post (now
                          Mama's Caf[eacute],
                          Herbs and Art, and
                          Purple Haze).
OU9B*..................  Robinson Brick and Tile  500 South Santa Fe
                          Company (ROBCO) Metals   Drive.
                          (now Home Depot).
OU10...................  Card Corp..............  1314 West Evans
                                                   Avenue.
OU11...................  Commercial Investors     1285-1295 South Santa
                          Realty (formerly owned   Fe Drive.
                          by Thomas Real Estate
                          Corp.) (now Murphy
                          Beds and a Starbucks).
------------------------------------------------------------------------

Site History

OU1
    Contamination at OU1 resulted from a radium, vanadium, and uranium 
processing facility at 1201 Quivas Street owned by the Pittsburgh 
Radium Company (PRC) from 1925 until 1926. The Radium Ores Company, 
which was associated with PRC, operated the facility until 
approximately 1927. Approximately 120 tons of carnotite and 500 tons of 
vanadium were processed monthly.
OU2
    The contamination at Operable Unit 2 is believed to be from 
activities of the Schlesinger Radium Company which began operations in 
1914 where Atlas Metals & Iron (formerly DuWald Steel Corporation) 
currently is located (1100 Umatilla Street). In 1917, Schlesinger 
Radium Company became Radium Company of Colorado. Radium Company of 
Colorado ceased operations at OU2 in 1924. Complex Ore Recovery Company 
occupied the 1100 Umatilla property until 1928. It is not known whether 
that company also processed radium ore.
    Since 1914, at least 38 companies have operated within the operable 
unit. OU2, as originally designated, included only the 1100 Umatilla 
and 1020 and 1030 Yuma Street properties. The other properties were 
included as subsequent investigations revealed additional 
contamination.
OU3
    It is believed that the vacant lot, located at 1000 South Louisiana 
and owned by Packaging Corporation of America, may have been the site 
of a smelter that operated in the late 19th century. This smelter may 
have been turned into a radium-processing facility in the early 20th 
century. The Chemical Products Company, which occupied portions of OU3 
between 1918 and 1921, separated radium and vanadium from uranium ores 
for the National Radium Institute. Most of the buildings associated 
with radium processing were demolished prior to 1970. The exception was 
a brick building located at 1298 South Kalamath Street, which was 
purchased by Creative Illumination, Inc. and used for light-fixture 
fabrication. The Creative Illumination, Inc. building was demolished 
during remediation activities.
OU4/5
    OU4 (ROBCO) was the site of a radium processing facility 
established by the National Radium Institute (NRI) in 1913. The NRI 
facility was created for the purpose of developing and demonstrating 
the commercial feasibility of radium extraction techniques. This 
facility operated on the site for approximately four years and then 
closed after producing 7.5 grams of radium and successfully 
demonstrating commercially feasible extraction processes. ROBCO 
acquired the property in the 1940s and used it as a brick and tile-
manufacturing site until the 1980s. The radium-contaminated area of OU5 
(D&RGW right-of-way) covers 1.6 acres. This property is crossed by 
several rail lines and contains a network of electronic controls to 
operate railway lights and switches. OU5 has been in use as a railroad 
right-of-way throughout the

[[Page 54783]]

industrial and commercial use of the adjacent ROBCO property.
OU6, OU9A, OU11
    Much of the radiological contamination present at OU6, OU9A and 
OU11 is believed to be either the direct result of radium and uranium 
processing on the property or the result of deposition of residual 
wastes from other processing sites.
OU7
    These properties comprise a number of city streets which were 
underlain by radium-contaminated soil. Radium production from about 
1914 to the mid-1920s generated large quantities of radioactive 
residues in the Denver area. Radium-contaminated tailing and other 
wastes were discarded or left on site when the facilities were closed. 
Due to changes in ownership and use of the properties, the residues 
were used as cover, fill, foundation material, and as aggregate in 
concrete and asphalt mixtures.
OU8
    The Shattuck property has been the location of several mineral-
processing operations since the early 1900s. The operations included 
the extraction of molybdenum and vanadium from ores, processing of 
``radium slimes'' for the production of radium salts and uranium 
compounds, recovery of rhenium as a by-product of molybdenum 
production, and for a short period of time processing of depleted 
uranium. The primary site contaminants were radium, thorium, uranium, 
molybdenum, arsenic, selenium, and several volatile and semi-volatile 
organics. Shattuck's operations ceased in 1984.
OU9B
    OU 9B-ROBCO Metals was designated to distinguish response actions 
addressing metals contamination from response actions addressing the 
OUs 4/5 radium contamination. In May 1988, excavation of the 
radiologically contaminated soil began at OUs 4/5. In September 1988, 
during the course of the radium cleanup, metals contamination was 
discovered on the ROBCO property. Contaminants of concern included 
arsenic, lead, and zinc. An investigation to characterize the nature 
and extent of metals contamination was conducted in 1989 and 1990. This 
metal contamination is believed to be from the operation of the Tabor 
Smelter on this property in the 1880s and 1890s.
OU10
    Contamination at OU10 was from PRC processing of vanadium between 
1920 and 1924. During 1924, PRC is believed to have processed as much 
as 10 tons of vanadium daily. OU1-OU11, with the exception of OU8 
groundwater, are proposed for partial deletion.

Characterization of Risk

    Radium and its associated decay products were the primary 
contaminants of concern at the Denver Radium Site. Other contaminants 
at the site were thorium, uranium, arsenic, zinc, and lead.
    The elevated concentration of radium and the uncontrolled state of 
contaminants at the Denver Radium Site posed a health hazard due to 
three potential exposure pathways: Inhalation of radon gas and its 
decay products, direct gamma radiation exposure from the decay of 
radium and ingestion or inhalation of radium-contaminated materials. 
Ingestion or contact with contaminated groundwater is not a principal 
exposure pathway. There is no surface water on site.
    Inhalation of radon decay products presents the greatest health 
risk from long-term exposure. Prolonged inhalation of air with a high 
concentration of radon decay products has been conclusively shown to 
increase the risk of lung cancer. Dispersion quickly dilutes radon 
emanating from radium-contaminated ground. The greatest risk from radon 
is when it builds up in well-sealed buildings. Radon decay product 
contamination in buildings (where applicable) was as much as 0.30 
working levels (WL) above the EPA standard of 0.02.

Remedial Investigation and Feasibility Study

    The Remedial Investigation (RI) report for the Denver Radium 
Superfund Site was issued in April 1986. The Feasibility Study (FS) was 
issued in September 1987. The site-wide RI focused on radium and 
uranium processing residues discarded in the early 1900s. These 
residues contain uranium, radium, and thorium.
    A number of Remedial Action alternatives were evaluated in the 
site-wide FS including: No Action; On-Site Processing with Permanent 
Disposal; In-Situ Vitrification; On-Site Permanent Disposal; Off-Site 
Permanent Disposal, and On-Site Temporary Containment with Off-Site 
Permanent Disposal. These site-wide RI and FS reports provided the 
basis for selecting remedies in most of the Records of Decision. 
Separate RI/FS reports were generated for the metals contamination at 
OU4 (ROBCO) and the contamination at OU8 (Shattuck).

Remedial Action Objectives

    The following objectives were identified for soil across the site:
    Remedial actions shall be conducted so as to provide reasonable 
assurance that, as a result of residual radioactive materials from any 
designated processing site:
    (a) The concentration of radium-226 in land averaged over any area 
of 100 square meters shall not exceed the background level by more 
than--
    (1) 5 pCi/g, averaged over the first 15 centimeters of soil below 
the surface, and
    (2) 15 pCi/g, averaged over 15-centimeter thick layers of soil more 
than 15 centimeters below the surface.

Supplemental Standards: (OUs 2, 3, 4, 9B)

    40 CFR Part 192 provides that under certain circumstances the 
agency performing the cleanup may choose a remedial action that does 
not achieve complete removal of radium contamination to the levels 
described in 40 CFR Section 192.12(a). Under 40 CFR Section 192.21(c), 
``supplemental standards'' can be applied when:

    ``The estimated cost of remedial action to satisfy 40 CFR 
Section 192.12(a) at a * * * site * * * is unreasonably high 
relative to the long-term benefits, and the residual radioactive 
materials do not pose a clear present or future hazard. The 
likelihood that buildings will be erected or that people will spend 
long periods of time at such a vicinity site should be considered in 
evaluating this hazard. Remedial action will generally not be 
necessary where residual radioactive materials have been placed 
semi-permanently in a location where site-specific factors limit 
their hazard and from which they are costly or difficult to remove, 
or where only minor quantities of residual radioactive materials are 
involved. Examples are residual radioactive materials under hard 
surface public roads and sidewalks, around public sewer lines, or in 
fence post foundations.''

    The following objectives were identified for buildings across the 
site:
    (b) In any occupied or habitable building--
    (1) The objective of remedial action shall be, and reasonable 
effort shall be made to achieve, an annual average (or equivalent) 
radon decay product concentration (including background) not to exceed 
0.02 WL. In any case, the radon decay product concentration (including 
background) shall not exceed 0.03 WL, and
    (2) The level of gamma radiation shall not exceed the background 
level by more than 20 microroentgens per hour.

[[Page 54784]]

    The following objectives were identified for groundwater:
    OU8--Restoration of groundwater quality to Safe Drinking Water Act 
maximum contaminant levels through monitored natural attenuation.
    OU9B--No remedial action objectives were identified for groundwater 
because the alluvial aquifer is not presently used as a drinking water 
source and is unlikely to be used as a drinking water source due to 
poor natural quality (i.e., high total dissolved solids), low yield, 
and its location (i.e., in an industrial area between a major rail 
corridor and an interstate highway). Groundwater protection is achieved 
by controlling the source of contamination and periodic monitoring to 
verify that contamination does not reach the South Platte River in 
detrimental concentrations. Deed restrictions include a prohibition on 
placement of any wells on the Site for the purpose of supplying 
drinking water.

Selected Remedies

    The RODs for OUs 1, 2, 3, 4/5, 6/9/11, and 10 each selected 
excavation and off-site permanent disposal as the remedy. At the time 
the RODs were signed, there were no disposal facilities in the nation 
that accepted radioactive waste. For this reason, the RODs included 
temporary on-site land storage of the contaminated materials with 
subsequent off-site permanent disposal. Plans for on-site temporary 
land storage were abandoned for all operable units, with the exception 
of OU 4/5, when a permanent disposal facility opened before excavation 
began. Excavated material was shipped by rail to Envirocare of Utah, 
Inc., a disposal facility in Tooele County, Utah. For OU 4/5, 
contaminated soil was stockpiled on the ROBCO property until the 
permanent disposal facility became available and a transportation 
contract was negotiated.
OU1
    In the Record of Decision (ROD), dated September 1987, EPA selected 
excavation and off-site disposal as the remedy for OU1. The objectives 
of this remedy were to prevent: Radiation exposure due to inhalation of 
radon gas and its daughter products; radiation exposure due to 
inhalation and ingestion of long-lived radionuclides; and direct 
exposure to gamma radiation.
OU2
    In the ROD, dated September 1987, EPA selected excavation and off-
site permanent disposal as the remedy for OU2. The objectives of this 
remedy were to prevent: Radiation exposure due to inhalation of radon 
gas and its daughter products; radiation exposure due to inhalation and 
ingestion of long-lived radionuclides; and direct exposure to gamma 
radiation.
    The scope of Remedial Action detailed in the ROD included:
     Decontaminating the roof of the Rocky Mountain Research 
Corporation building and excavating the majority of the approximately 
15,400 cubic yards of contaminated material located under buildings and 
in open areas on the properties, and placing the material in a 
temporary on-site land storage facility,
     Maintaining the 6-inch-thick concrete pad, covering 
contaminated soil on the northeast part of the Atlas Metals & Iron 
(formerly DuWald Steel Corporation) property,
     Removing the contaminated material from the temporary 
storage and containment locations to the permanent disposal facility 
when such a facility became available.
    In September 1993, EPA issued an Explanation of Significant 
Differences (ESD) to address on-site conditions that became apparent 
after the ROD was signed. The changes made to the remedy selected for 
OU2 in the ROD were:
     A greater volume of radium-contaminated soil was excavated 
and removed.
     Relatively small amounts of radium contamination were left 
on the 1100 Umatilla Street property. Radium contaminated soil was left 
in place in the following locations: (a) Under structures on the Du-
Wald property, (b) near the underground power line, (c) within a four 
foot buffer zone around water and sewer lines, (d) below the ground 
water level, and (e) on the Burlington Northern Railroad (BNRR) right-
of-way.
     Institutional controls (ICs) were required where waste was 
left in place.
     There was no temporary on-site storage.
     Soil containing commingled radium and lead was solidified 
in a cement matrix prior to shipment to a permanent, off-site disposal 
facility.
OU3
    In the ROD, dated September 1987, EPA selected excavation and off-
site disposal as the remedy for OU3. The objectives of this remedy were 
to prevent: Radiation exposure due to inhalation of radon gas and its 
daughter products; radiation exposure due to inhalation and ingestion 
of long-lived radionuclides; and direct exposure to gamma radiation.
    In December 1993, EPA issued an ESD to address on-site conditions 
that became apparent after the ROD was signed. The ESD presents the 
changes that were made to the remedy selected for OU3; briefly, the 
differences were:
     No temporary storage prior to removal and shipment of 
contaminated material to the permanent off-site disposal facility.
     Over 52,000 cubic yards of contaminated soil were 
excavated and the area of contamination was extended east of South 
Jason Street.
     As part of the remediation, the Creative Illumination 
building was demolished, contaminated material was removed, and the 
contaminated materials were shipped to the off-site repository.
     There was no excavation of contaminated soil below 
groundwater, near water lines, or under South Jason Street, Platte 
River Drive and the Packaging Corporation of America building.
     ICs were required where waste was left in place.
OU4/5
    EPA selected excavation and off-site disposal as the remedy for 
this OU in a ROD dated September 30, 1986. The objectives of this 
remedy were to prevent: Radiation exposure due to inhalation of radon 
gas and its daughter products; radiation exposure due to inhalation and 
ingestion of long-lived radionuclides; and direct exposure to gamma 
radiation. The ROD determined that the shallow alluvial aquifer is not 
a drinking water source.
    In December 1994, EPA issued an ESD to address on-site conditions 
that became apparent after the ROD was signed. The ESD describes in 
more detail the changes that were made to the remedy selected for OU4 
and OU5. The remedy, as implemented, differed in two respects from the 
remedy chosen in the 1986 ROD. Those differences were:
     The volume of contaminated soil increased; and
     Relatively small volumes of contaminated soil were left in 
place below the groundwater level.
     ICs were required on the OU4 property where wastes were 
left in place.
OU6, OU9A, OU11
    EPA selected excavation and off-site disposal as the remedy for 
OU6, OU9A, and OU11 in a ROD dated September 29, 1987. The objectives 
of this remedy were to prevent: Radiation exposure due to inhalation of 
radon gas and its daughter products; radiation exposure due to 
inhalation and ingestion of long-lived radionuclides; and direct 
exposure to gamma radiation.

[[Page 54785]]

    Remedial design at these operable units focused on excavation and 
direct off-site disposal of radiologic waste materials.
    In January 1995, EPA issued an ESD to address on-site conditions 
that became apparent after the ROD was signed. The ESD describes the 
changes that were made to the remedy selected for OU6, OU9A, and OU11. 
Briefly, these differences include:
     A relatively small volume of radium-contaminated soil was 
left in place at the following locations in OU6: a) near a concrete box 
culvert on the Confluence Park property; and b) under the Environmental 
Materials (EMI) Building.
     ICs were required on the OU6 property where wastes were 
left in place. Note: Even though the 1995 ESD describes waste left in 
place, all contamination was subsequently removed. ICs are not 
required.
     Additional properties were found to be contaminated and a 
greater volume of radium-contaminated soil was excavated and placed in 
a permanent off-site repository.
     Soil commingled with metals contamination was shipped to 
the permanent off-site disposal facility.
OU7
    EPA issued a ROD for OU7 on March 24, 1986 that combined features 
of the Excavation and Off-site Disposal alternative with a no action 
alternative. The ROD called for leaving the contaminated material in-
place and required ICs to monitor all maintenance, repair, or 
construction activities in the affected streets. Any contaminated 
material excavated during these activities would be shipped off site 
for disposal.
    The objectives of this remedy were to prevent: Radiation exposure 
due to inhalation of radon gas and its daughter products; radiation 
exposure due to inhalation and ingestion of long-lived radionuclides; 
and direct exposure to gamma radiation.
    In September 1992, EPA issued an ESD to address on-site conditions 
that became apparent after the ROD was signed. This ESD amended the 
existing ROD to allow for reburial of excavated materials. The 
significant difference from the original remedy allows on-site 
retention and reburial of radium-contaminated material excavated during 
all maintenance, repair or other construction activities. Should 
maintenance, repair or other construction activities be required, 
excavated radium-contaminated materials will be retained and reburied 
on site if feasible, provided that the area to be excavated is not 
greater than 20% of the total area of the roadway in one city block. 
Special variance to the 20% limit may be granted by the CDPHE should an 
unusual circumstance require such a variance. Reburied materials will 
be covered with a new, hard surface, such as asphalt or concrete having 
a minimum depth of 6 inches to ensure no direct exposure. If retention 
and reburial are not feasible, the materials will be disposed at a 
licensed, off-site disposal facility, consistent with the ROD.
OU8
    The original ROD for Shattuck was signed on January 28, 1992. EPA 
selected on-site soil stabilization and solidification to prevent 
further degradation of groundwater and allow for natural attenuation 
with monitoring for groundwater. Groundwater monitoring will be 
performed to (1) monitor the effectiveness of source control measures, 
and (2) monitor attenuation of the plume until it meets maximum 
contaminant levels for contaminants of concern. An IC program was an 
integral part of the remedy and required restrictions against 
excavating into the cover and stabilized materials, prohibition of the 
construction of enclosed structures on the disposal site, restrictions 
against the use of groundwater, and restrictions to prevent 
agricultural use of the site. In 1999, EPA conducted a discretionary 
five-year-review of the Shattuck OU and found deficiencies in aspects 
of the design and integrity of the on-site disposal cell. Based on 
these findings, EPA could not be assured of the long-term protection of 
the original remedy. In addition to the technical concerns raised by 
the 1999 five-year review, the State, Denver, elected officials, and 
the local community requested that EPA consider other alternatives to 
the on-site remedy to allow for unrestricted use of the site.
    In June 2000, after developing a proposed plan and receiving public 
input, EPA selected off-site removal in a ROD Amendment. Off-site 
disposal benefits included the following:
     Long-term protection of human health and the environment;
     Removal of potential source material for future 
groundwater contamination;
     Disposal of material in a permitted facility;
     Unrestricted future land use; and
     Monitored attenuation of the plume until it meets maximum 
contaminant levels for contaminants of concern for groundwater use 
remain as required in the 1992 Record of Decision.

An ESD was issued for the Shattuck Site in February 2007. The ESD was 
required due to the elevated costs from the original estimate based on 
the 2000 ROD. The 2000 estimate cost for the off-site removal was $29 
million with a final cost of $57 million. Reasons for the increased 
costs are described in the ESD.
OU9B
    As discussed above, OU9B was designated when substantial metals-
contaminated soil, not commingled with radium wastes, was discovered 
during implementation of the OU 4/5 remedy. At this OU, EPA selected a 
remedy leaving the metals-contaminated soil on site under a protective 
soil cover and implemented ICs. The objectives of the remedy were to:
     Prevent direct contact with or ingestion of metals-
contaminated soil that exceeds the health-based action levels and 
monitor migration of the contaminants of concern in groundwater that 
could result in degradation of water quality in the South Platte River.
     Cap the metals-contaminated soil, conduct environmental 
monitoring to ensure the effectiveness of the Remedial Action, and 
implement ICs to limit use of groundwater at the site and maintain the 
integrity of the cap.
OU10
    In the ROD, dated June 30, 1987, EPA selected excavation and off-
site disposal as the remedy for OU10. The objectives of this remedy 
were to prevent: Radiation exposure due to inhalation of radon gas and 
its daughter products; radiation exposure due to inhalation and 
ingestion of long-lived radionuclides; and direct exposure to gamma 
radiation.

Response Actions

OU1
    Remediation activities at OU1 were conducted in three phases to 
facilitate construction and to accommodate the various business 
activities in the unit. Construction began on October 2, 1989 and 
concluded on July 18, 1991. The quantity of material removed during 
remediation was 32,665 tons.
OU2
    Remedial Actions at OU2 began in August 1990 and, except for ICs, 
were completed in August 1993. Activities included:
     Excavation of radium-contaminated soil in open areas.
     Analysis of the contaminated materials for disposal to 
ensure compliance with transportation and disposal regulations.

[[Page 54786]]

     Shipment of contaminated materials to the permanent off-
site disposal facility.
     Confirmation sampling of excavated area.
    A total of 14,211 tons of radiologic and commingled material was 
excavated and shipped off site. The commingled material was stabilized 
by solidification prior to off-site disposal. A Supplemental Standards 
Report was prepared in May 1994 to document that 11,060 cubic yards of 
radiological contaminated soil were left in place on the Burlington 
Northern Railroad property and the 1100 Umatilla Street property (Atlas 
Metals and Iron) at OU2.
    Pursuant to the terms of an administrative settlement agreement 
(November 22, 2005), the current owner of the former DuWald property, 
Atlas Umatilla, LLC, has prepared and is implementing an O&M Plan and 
signed and executed an environmental covenant on June 25, 2006. The 
environmental covenant restricts disturbance of the concrete cap and 
subsurface soil. In addition, Denver's zoning ordinance and its radium 
fee ordinance provide ICs generally at properties in OU2 where radium-
contaminated soil remains in place under supplemental standards.
OU3
    Remedial Actions at OU3 began in August 1989 and were completed in 
September 1991. A phased approach to the cleanup allowed on-site 
businesses to maintain operations throughout the excavation and 
shipment of 63,672 tons of contaminated material from OU3. Activities 
included:
     Excavation of radium-contaminated soil in open areas;
     Demolition of certain radium-contaminated buildings;
     Analysis of the contaminated materials to be disposed to 
ensure compliance with transportation and disposal regulations;
     Shipment of contaminated materials to the permanent off-
site disposal facility; and
     Confirmation sampling of excavated area.
    The Creative Illumination building was demolished and 3,657 tons of 
radium-contaminated materials were excavated and removed from this 
location. A total of 32,389 tons of radium-contaminated soil was 
excavated and removed from the Packaging Corporation of America (PCA) 
property and a vacant lot owned by PCA located at 1000 West Louisiana. 
Other activities included the excavation and off-site disposal of 
27,626 tons of radiologically contaminated soil. Remediation of OU3 was 
completed when 50 tons of radiologically contaminated soil were 
excavated from the GT Car Shop and Aspen Design and Manufacturing 
properties for off-site disposal.
OU4/5
    Remedial Action at OU4 and OU5 included the following:
     Excavation of radium-contaminated soil;
     Demolition of certain radium-contaminated buildings;
     Analysis of the contaminated materials to ensure 
compliance with transportation and disposal regulations;
     Shipment of contaminated materials to the permanent off-
site facility; and
     Confirmation sampling of excavated area.
    Remedial Action at OU4/5 was conducted in phases, beginning in 
April 1988 and, except for ICs, completed in March 1991. A total of 
57,586 tons of radiologically contaminated material was excavated 
during the initial phase of the cleanup. This material was stockpiled 
on site temporarily until it could be transported to the off-site 
disposal facility. Approximately 1,290 tons of soil, contaminated with 
elevated levels of Thorium-230, were removed during a later phase of 
the project. The stockpiled material, as well as an additional 9,677 
tons of contaminated material situated immediately below the stockpile, 
were shipped during a later phase of the cleanup. Finally, 29,721 tons 
of radiologically contaminated soil were excavated and transported by 
rail in covered gondola cars to a permanent off-site disposal facility 
operated by Envirocare of Utah, Inc., in Tooele County, Utah. Of this 
total, 2,100 tons were contaminated with metals as well as radioactive 
material. A Supplemental Standards Report, prepared in March 1994, 
documented radiological contamination that remained on site at OU4. 
Materials left in place are located at 500 South Santa Fe Drive 
(ROBCO); and the Burlington Northern Railroad ROW immediately east of 
ROBCO (OU4).
    Pursuant to the terms of the Agreement and Covenant Not To Sue 
(July, 1995; also called the Prospective Purchaser Agreement (Home 
Depot PPA), Home Depot USA (Home Depot) placed a restrictive covenant 
on OU4. The restrictive covenant restricts future use of the areas 
where radiological contamination was left in place under supplemental 
standards. In addition, Denver's zoning ordinance and its radium fee 
ordinance provide ICs generally at properties in OU 4/5 where radium-
contaminated soil remains in place under supplemental standards. Also, 
the PPA provides additional ICs for this operable unit.
OU6, OU9A, OU11
    Remedial Action operations at OU6, OU9A, and OU11 included the 
following:
     Excavation of radium-contaminated soil;
     The analysis of the contaminated materials to ensure 
compliance with transportation and disposal regulations;
     Shipment of contaminated materials to the permanent off-
site disposal facility; and
     Confirmation sampling of excavated area.
    Remediation was conducted in phases to facilitate the cleanup and 
to accommodate the various business activities within these operable 
units. Remediation began in March 1989 and was completed in December 
1993. During the Remedial Action for OU6, OU9A, and OU11, 8,336 tons of 
contaminated soil were excavated and disposed off site.
    118 tons of contaminated soil were excavated from a property at 
South Pecos Street and West Arizona Avenue and disposed off site. The 
excavated area was backfilled with clean soil and re-vegetated. Various 
properties within OU6, OU9A and OU11 also were remediated and a total 
of 5,365 tons of material were excavated for off-site disposal. A total 
of 2,403 tons of contaminated soil was excavated from the Environmental 
Materials, Inc. (EMI) and Regional Transportation District properties. 
This soil was transported by rail to the permanent disposal facility in 
Utah. In 1993, during the final phase, 450 tons of contaminated soil 
were excavated from the EMI property and transported by rail to the 
permanent disposal facility in Utah. Even though the 1995 ESD spoke 
about supplemental standards applying to OU6, all contamination was 
subsequently removed, thus, institutional controls are not required.
OU7
    The EPA selected remedy combines features of excavation and 
disposal with the modified no action alternative. This remedy entails:
     Leaving the contaminated material in place;
     Improving ICs so that all routine maintenance, repair and 
construction activities in the affected streets by government agencies, 
utility companies, contracting companies, and private individuals will 
be monitored; and

[[Page 54787]]

     Removing any contaminated material excavated during 
routine maintenance, repair, or construction activities in the affected 
streets to a facility approved for storage or disposal of contaminated 
material.
     Due to the location, nature, and volume of radioactive 
contamination at OU7, the modified no action alternative was 
implemented at this operable unit. The potential routes of human 
exposure to the radioactivity are limited since the contaminated 
material is bound in the asphalt and is not free to move in any 
direction. None of the streets are near surface water or groundwater 
resources and the material has little potential for erosion or leaching 
because the contaminated aggregate is bound in the asphalt matrix 
within the pavement cap. Thus, the contamination in the asphalt matrix 
does not pose a threat to human health or the environment if left 
undisturbed.
    The City and County of Denver has been actively managing the radium 
materials for many years. This active management served as the ICs for 
this operable unit. Due to the effort, requiring annual training for 
city and utility workers and the financial commitment, the City and 
County of Denver opted to ensure long-term public health and safety by 
removing the contaminated material from these streets in OU7. This 
action included the removal of asphalt and any contaminated road base 
and fill material.
    As part of the Denver Radium Streets Program, between 2003 and 2007 
Denver removed contamination from the following properties: South 
Bannock Street; 11th Avenue from Race Street to Josephine; Marion 
Street from 6th Avenue to 10th Avenue; Humboldt Street from 7th to 9th 
Avenue; Lafayette Street from 1st Avenue to 10th Avenue; Downing Street 
from 7th to 10th Avenue; 9th Avenue from Ogden to Franklin Street; 
Corona Street from 7th to 10 Avenue; Park Avenue West from Arapahoe to 
California Street; York from 6th to 13th Avenue. In addition, the 
Denver Streets portion of OU3, Jason Street, was remediated in 2007. As 
a result of these actions, there is no waste left in place within 
Operable Unit 7, and ICs are not required.
OU8
    The initial Remedial Action at OU8 was substantially completed in 
September 1998. Remedial Action at OU8 included the following:
     Demolition of radium-contaminated buildings;
     Excavation of radium-contaminated soil from vicinity 
properties, Bannock Street, the storm sewer located east of Santa Fe 
Drive, and the Shattuck Chemical property;
     On-site stabilization/solidification of the radium-
contaminated soil into a disposal cell;
     Capping of the stabilized material; and
     Installation of monitoring wells to evaluate the 
effectiveness of the remedy.
    The Remedial Action at OU8 was conducted in two phases, beginning 
September 1992, and was substantially complete in September 1998. 
During Phase I approximately 67,345 tons of building debris were 
disposed off site and 8,700 cubic yards of soil were excavated from the 
vicinity properties. During this phase, approximately 200 cubic yards 
of asbestos containing material were removed and disposed under 
appropriate regulations. Approximately 400 cubic yards of 
radiologically contaminated material were excavated from beneath 
Bannock Street. Stabilization/solidification of the radiologically 
contaminated material began in July 1996 and was completed in November 
1997.
    Approximately 65,000 loose cubic yards of radiologically 
contaminated soil excavated from Shattuck Chemical and the vicinity 
properties were stabilized/solidified on site in a disposal cell. 
Capping of the stabilized material was completed in June 1998. ICs were 
implemented through a Declaration of Covenants and Restrictions, filed 
with the City and County of Denver on March 25, 1999, that restricted 
surface and groundwater use.
    During the excavation of radiologically contaminated soil, oil-
impacted soil also was found on site. The materials were below the 
action levels established in the ROD. Approximately 2,000 cubic yards 
of oil-impacted soil were excavated from the Shattuck Chemical Property 
located at 1805 South Bannock Street during Phase 2 activities. This 
material was covered and transported by truck to Conservation Services, 
Inc. in Thornton, Colorado. Bioremediation was used for oil-impacted 
soil that extended beneath the completed portion of the monolith. A 
plan addressing the remaining oil-contaminated soil at OU8 was 
submitted in August 1998. The bio-venting system was approved by EPA 
and was installed in September 1998.
    In 1997, the storm sewer along Santa Fe Boulevard west of the site 
was remediated. During the remediation, an in-situ form liner was 
installed into the original pipe to isolate storm water discharges to 
the South Platte River from the influx of contaminated groundwater. 
This liner system, while in place, did not remedy the problem. In 1998, 
the sewer remediation was investigated by EPA and the City of Denver 
and determined to be incomplete. The City and County of Denver 
installed a new sewer cutoff that has significantly limited the amount 
of potential infiltration into the sewer line along Bannock Street. A 
management plan for OU8 Bannock Street was developed and adopted in 
March 1999 by the City and County of Denver to govern all maintenance, 
repair, or other construction activities at OU8 Bannock Street.
    In 1999, the EPA conducted a discretionary five-year review of the 
monolith and found deficiencies in the cover design and the structural 
and chemical integrity of the structure. EPA concluded that it could 
not assure the long-term protectiveness of this remedy. The June 2000 
amended ROD required removal of 100,000 cubic yards of the material and 
full cleanup of the site. Groundwater quality will continue to be 
monitored until performance standards are met; therefore, the 
groundwater is not part of this partial deletion.
    EPA began to remove the contaminated soil and monolith in March 
2003 to U.S. Ecology, a permitted facility in Grandview, Idaho. Waste 
shipments began on March 9, 2003. A total of 243,872 tons of 
contaminated soil and materials was removed by the fall of 2006. The 
site has been verified to be clean and restored. Clean excavation and 
fill material was backfilled into all open areas where the 
contamination was removed and has been returned to grade. The covenant 
restricting surface and groundwater use was later modified to remove 
the surface use restrictions.
    The Amended Declaration of Covenants and Restrictions was filed in 
2007. However, there are still elevated levels of contaminants in 
groundwater including uranium, arsenic, cadmium, selenium, molybdenum, 
and gross alpha and gross beta radioactivity. In addition to the 
restrictive covenant, a restriction notifying each well permit 
applicant about the potential for contamination in the groundwater was 
placed July 17, 2006 on OU8 through the Colorado Office of the State 
Engineer.
OU9B
    The Remedial Action at OU9B (ROBCO Metals) was completed in three 
phases, beginning in October 1995 and completed in April 1996. During 
Phase 1 activities, the ROBCO Site was prepared for the excavation, 
movement and consolidation of heavy metal contaminated soil. During 
Phase 2 activities, the existing ROBCO Building/

[[Page 54788]]

Plant foundation was demolished and the area of contamination outside 
the Area of Consolidation was excavated. Approximately 62,062 cubic 
yards of material were excavated and/or moved during Phase 2 of the 
Remedial Action. During Phase 3 activities, the Area of Consolidation 
cap was constructed, the identification barrier was installed, and 
structural fill was placed and compacted to final design grade and 
contour.
    In accordance with the Home Depot PPA, Home Depot, USEPA, and CDPHE 
performed closure of the Robinson Brick Company in a defined ``shared'' 
and ``phased'' manner. Home Depot submitted a Draft O&M Plan on May 30, 
1997. CDPHE and EPA approved the O&M Plan on March 17, 1998. Based on 
the O&M Plan, EPA and CDPHE will perform biannual, off-site groundwater 
monitoring and Home Depot will perform biannual inspections of store 
facilities and site utilities.
    The restrictive covenant that Home Depot recorded for OU 4/5 waste 
also covers the OU 9B heavy metal contamination. The restrictive 
covenant prohibits disturbance of the Area of Consolidation and 
prohibits use of groundwater.
    The Home Depot PPA requires that any breaches of the soil cap 
system over the Post-Consolidation Area of Contamination will be 
reported to EPA and CDPHE with the requirement that new construction, 
remodeling and site repair generally will not be conducted in this 
area.
OU10
    Remediation activities at OU10 began in September 1988 and ended 
September 22, 1989. A total of 15,021 tons of materials with depths 
raging from 0 to 80 inches was removed and was disposed off site at 
Envirocare of Utah.
    No extensive changes were made to the major structures on the 
property, although several small structures were removed and not 
replaced at the request of the owner. Some un-assessed contamination 
required removal, but the volumes were not large.

Cleanup Standards

    For radiological contamination, EPA calculates risk based on area 
averaging of several measurements over 100 square meters. When these 
calculations are below the EPA surface standard of less than 5 pCi/g 
above background and below the subsurface standard of 15 pCi/g above 
background, the area is considered safe for unlimited use and 
unrestricted exposure as long as soil at depth with 15 pCi/g above 
background remains at depth.

Operation and Maintenance

    The City and County of Denver have agreed to implement a management 
plan for radium-contaminated soil remaining in place in Denver's 
rights-of-way and to continue to enforce Denver's zoning ordinance and 
its radium fee ordinance as ICs at private properties where radium-
contaminated soil remains in place under supplemental standards. The 
management plan and ordinances provide ICs wherever supplemental 
standards apply across the Site. Specifically, these institutional 
controls apply to waste left in place at Operable Units 2, 3, and 4.
    In addition to the Denver management plan and ordinances, EPA has 
agreements in place with owners of other operable units whereby those 
owners have agreed to manage waste left in place and provide 
institutional controls. These additional controls include limitations 
on the use of groundwater at OUs 8 and 9B. Those operable units are 
described below.
OU2
    Pursuant to the terms of a settlement agreement, the current owner 
of the Umatilla property, formerly DuWald property, Atlas Umatilla, 
LLC, has prepared an O&M Plan and signed and executed an environmental 
covenant on June 25, 2006. The environmental covenant restricts 
disturbance of the concrete cap and subsurface soil. In addition, 
indoor air quality will be monitored.
OU4/5 & 9B
    Pursuant to the terms of the Home Depot PPA, Home Depot prepared an 
O&M Plan and placed a restrictive covenant on OU4. The restrictive 
covenant restricts future use of the areas where wastes were left in 
place, including the area of consolidation of metal wastes and the 
radioactive waste left in place under supplemental standards. Home 
Depot has an amended O&M Plan as of August 18, 2003.

Five-Year Reviews

    Remedial actions which result in any hazardous substances, 
pollutants, or contaminants remaining on site will be subject to 
statutory five-year reviews. The purpose of a five-year review is to 
evaluate the implementation and performance of a remedy to ensure that 
the remedy is and remains protective of public health and the 
environment.
    The first five-year review was completed in September of 1993, 
triggered by remedial actions at OU 4/5. The first five-year review 
addressed OU 4/5 only. The following year, a site-wide review was 
completed on September 12, 1994. No modifications or improvements to 
the remedy were suggested in these first two reviews.
    A discretionary five-year review, conducted in 1999 for OU8 only, 
identified concerns with the long-term effectiveness of the on-site 
remedy. The remedy was modified in 2000, and remediation was completed 
in 2006.
    Another site-wide five-year review was completed in 2003. This 
review identified (1) deficiencies in ICs at three OUs and (2) new 
requirements for risk assessments where waste was left in place under 
supplemental standards. ICs have since been implemented and the risk 
assessments were revised. No modifications to the selected remedies 
were required.
    The 2008 Five-Year Review identified a few issues, however none of 
them affected current or future protectiveness. The review found that 
because the remedial actions at all OUs are protective, the Site is 
protective of human health and the environment.
    Since waste is left in place, five-year reviews will continue 
indefinitely to ensure continued protectiveness of the remedies. The 
next statutory five-year review is scheduled September 2013.

Community Involvement

    EPA's Community Relations Plan involved the community in the 
decision process for selecting all remedies for the Denver Radium Site 
and promoted communications among interested parties throughout the 
duration of the project.
    Community relation's activities included:
     Briefing State and local officials, public interest 
groups, neighborhood associations, interested citizens, and media 
representatives on the status of the various phases of the project,
     Conducting public meetings to keep citizens informed of 
the progress of the Denver Radium Site project and to solicit comments,
     Establishing information centers at the Denver Public 
Library and the EPA's Denver Superfund Records Center to make available 
for public review the study reports, site air-monitoring data, 
supplemental assessments, and other Denver Radium Site information,
     Maintaining a mailing list of interested parties and 
distributing i