National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science

Interim Inventory and Assessment of Abandoned 

Mineral Lands in the National Park System

Natural Resource Technical Report NPS/NRSS/GRD/NRTR-2013/659
ON THIS PAGE

Skidoo Mill, Death Valley National Park (NPS photo)

ON THE COVER

From upper left to bottom right: headframe over inclined shaft at Duchess Mine, Capitol Reef National Park; 

Kennecott Mill, Wrangell-St. Elias National Park and Preserve; Stone Cliff Coal Mine, New River Gorge 

National River; open stope at Skidoo Mine, Death Valley National Park (NPS photos)
 National Park Service i

Interim Inventory and Assessment of Abandoned 

Mineral Lands in the National Park System

Natural Resource Technical Report NPS/NRSS/GRD/NRTR-2013/659 

John E. Burghardt, Elizabeth S. Norby, and Harold S. Pranger II

National Park Service, Geologic Resources Division

P. O. Box 25287

Denver, CO 80225-0287

January 2013

U.S. Department of the Interior

National Park Service

Natural Resource Stewardship and Science 

Fort Collins, Colorado
ii Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, Colorado, 

publishes a range of reports that address natural resource topics. These reports are of interest and 

applicability to a broad audience in the National Park Service (NPS) and others in natural resource 

management, including scientists, conservation and environmental constituencies, and the public. 

The Natural Resource Technical Report Series is used to disseminate results of scientific studies in the 

physical, biological, and social sciences for both the advancement of science and the achievement of the 

National Park Service mission. The series provides contributors with a forum for displaying comprehensive 

data that are often deleted from journals because of page limitations. 

All manuscripts in the series receive the appropriate level of peer review to ensure that the information is 

scientifically credible, technically accurate, appropriately written for the intended audience, and designed and 

published in a professional manner. 

This report received formal peer review by subject-matter experts who were not directly involved in 

the collection, analysis, or reporting of the data, and whose background and expertise put them on par 

technically and scientifically with the authors of the information.

Views, statements, findings, conclusions, recommendations, and data in this report do not necessarily reflect 

views and policies of the National Park Service, U.S. Department of the Interior. Mention of trade names or 

commercial products does not constitute endorsement or recommendation for use by the U.S. Government.

This report is available from the National Park Service, Geologic Resources Division (http://nature.nps.gov/

geology/aml/inventory) and the Natural Resource Publications Management website (http://www.nature.nps.

gov/publications/nrpm).

Please cite this publication as:

Burghardt, J.E., E.S. Norby, and H.S. Pranger II. Interim inventory and assessment of abandoned mineral 

lands in the National Park System. Natural Resource Technical Report NPS/NRSS/GRD/NRTR-2013/659. 

National Park Service, Fort Collins, Colorado.

TIC Number: 999/119401
 National Park Service iii

Contents

List of Figures � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � iv

List of Tables � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � iv

List of Appendices � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �iv

Executive Summary � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � v

Acknowledgements � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �vi

Acronyms � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �vi

Terms � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � vii

Introduction � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �1

Background � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �2

Abandoned Mineral Lands in Parks � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �2

Abandoned Mineral Land Hazards and Impacts � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �3

AML Inventory and Assessment Methods. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �4

Mitigation Techniques for AML Features. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �6

Ranking Methodology for AML Features and Sites. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 12

Prioritization of Individual AML Features. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 12

Prioritization of AML Sites. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 12

Cost Estimation Procedure for AML Feature Mitigation. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 12

Results. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 13

Completion of California AML Inventory � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 15

Literature Cited. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 16

Appendices. � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 16

Appendix A: NPS AML feature types and descriptions � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 17

Appendix B: Discussion of AML feature ranking criteria considered for prioritization � � � � � � � � � � � � � � � � � � 20

Appendix C: Summary of data by region and park � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 23

Appendix D: NPS standard construction approach to estimating AML mitigation costs � � � � � � � � � � � � � � � � � 29
Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

List of Figures

Figure 1. Distribution of AML features in NPS units � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �2

Figure 2. Administrative closure sign at Keane Wonder Gold Mine, Death Valley National Park � � � � � � � � � �6

Figure 3. Fencing of large open stopes, El Portal Barite Mine, Yosemite National Park � � � � � � � � � � � � � �7

Figure 4. Cable mesh over open stull stope, Skidoo Gold Mine, Death Valley National Park � � � � � � � � � � � �7

Figure 5. Backfill of adit, Rainy Day Uranium Mine Capitol Reef National Park � � � � � � � � � � � � � � � � � �8

Figure 6. Polyurethane foam plug, Jones Branch Mine 195, Big South Fork National River and Recreation Area �8

Figure 7. Native rock and masonry wall and backfill, Jomac Uranium Mine, Glen Canyon 

National Recreation Area � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �9

Figure 8. Oil and gas well plugging operation, unnamed orphaned well, Big South Fork National 

River and Recreation Area � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �9

Figure 9. Steel grate installed over vertical shaft, Mariscal Mercury Mine, Big Bend National Park � � � � � � � � �9

Figure 10. Bat cupolas in Death Valley National Park and Mojave National Preserve � � � � � � � � � � � � � � � 10

Figure 11. Bat gates in adits at Buffalo National River and Lake Mead National Recreation Area � � � � � � � � 10

Figure 12. Sand Creek Gravel Pit #7, Great Sand Dunes National Park and Preserve � � � � � � � � � � � � � � 11

Figure 13. Dynamite found underground at El Cid Mine, Joshua Tree National Park � � � � � � � � � � � � � � 11

Figure 14. Distribution of AML features requiring mitigation � � � � � � � � � � � � � � � � � � � � � � � � � � 13

Figure 15. Costs to remediate high, medium, and low priority AML features � � � � � � � � � � � � � � � � � � 14

Figure 16. Prioritization by region of AML features that require mitigation � � � � � � � � � � � � � � � � � � � 14

List of Tables

Table 1. Data collected for NPS AML inventory � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �5

Table 2. Site prioritization results for AML features that require mitigation � � � � � � � � � � � � � � � � � � � 13

Table 3. Prioritization by region of AML features that require mitigation � � � � � � � � � � � � � � � � � � � � 15

List of Appendices

Appendix A: NPS AML feature types and descriptions � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 17

Appendix B: Discussion of AML feature ranking criteria considered for prioritization � � � � � � � � � � � � � � 20

Appendix C: Summary of AML data by region and park � � � � � � � � � � � � � � � � � � � � � � � � � � � � 23

Appendix D: NPS standard construction approach to estimating AML mitigation costs � � � � � � � � � � � � � 29
 National Park Service v

Executive Summary

This report presents the interim results of a System-wide National Park Service (NPS) inventory 

and assessment of its Abandoned Mineral Lands 

(AML) conducted from fiscal year (FY) 2010 

through FY 2012. This project has two primary 

objectives: 

● Complete a comprehensive inventory of AML 

sites in units of the National Park System that 

categorizes high, medium, and low priority 

mitigation needs; and 

● Estimate the resources needed to address 

priority issues with NPS AML features using a 

consistent, credible approach. 

By addressing these two main objectives, this report responds to key issues raised by the Office of 

the Inspector General (OIG) in its July 2008 Audit 

Report: Abandoned Mine Lands in the Department of the Interior (DOI 2008). It also responds 

to the NPS Director’s October 2, 2008, memorandum, which, in response to the OIG audit, directed 

regional and associate directors to update the NPS 

AML inventory and to identify the funding needed 

to address priority NPS AML features.

To date, 23,182 AML features have been identified 

in 129 units of the National Park System. Approximately 80% of the features are located in the 

Pacific West Region’s southern California desert 

parks, but all seven NPS regions have AML features. Commodities extracted vary regionally but 

generally include precious metals, base metals, and 

industrial minerals in the Alaska, Intermountain, 

and Pacific West Regions; uranium, oil, and gas in 

the Intermountain Region; and coal, oil, and gas in 

the Midwest, Northeast, and Southeast Regions. 

All regions have sand, gravel, and rock quarries. 

AML features are vestiges of a time when reclamation was not required by federal and state laws and 

policies, and many pose serious safety issues and 

resource impacts. Of the 23,182 features inventoried, 1,341 (5.8%) have received long-term treatment, 2,869 (12.4%) are in need of treatment, and 

the remainder, 18,972 (81.8%) have been inventoried to characterize each site but do not need 

treatment. 

The total estimated cost to remediate the 2,869 

AML features is $55.6 million. There are 2,435 

features in the high priority category that will cost 

approximately $44.9 million to remediate. Medium priority sites include 218 features that will 

cost approximately $7.5 million to remediate. Low 

priority sites include 216 features that will cost approximately $3.2 million to remediate. 

The inventory of NPS California units is scheduled 

for completion in late 2013. The current California 

parks inventory is just over 50% complete, and 

includes 14,428 features, 1,390 of which require 

mitigation at an estimated cost of $10.2 million. 

Those data are included in this report. Completion of the California inventory in 2013 will add 

additional features and costs to the Service-wide 

inventory. Upon completion of the California AML 

inventory, the NPS will update the data and analyses and issue a final AML Inventory & Assessment 

Report. The NPS is issuing this interim report for 

AML remediation planning purposes. 
vi Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

We wish to acknowledge the contributions of 

many individuals whose assistance was invaluable 

to the field inventory and assessment effort, and to 

production of this report. 

In particular, the members of the NPS Abandoned 

Mineral Lands Advisory Committee (AMLAC) coordinated park inventories, provided technical expertise, and reviewed work products. They include 

Linda Stromquist of the Alaska Region, Linda 

Dansby of the Intermountain Region, Chris Holbeck and Leo Acosta of the Midwest Region, Chris 

Stubbs and Diane Pavek of the National Capital 

Region, Andy Steel of the Northeast Region, Bob 

Bryson of the Pacific West Region, and Tom Blount 

and Todd Knoedler of the Southeast Region.

Support of numerous park staff in each of the 129 

NPS units that have AML was invaluable for field 

inventory coordination and data input. 

Acknowledgements

Data management was coordinated by Pascha Enzi 

and Nate Irwin. Report graphics were produced 

by Philip Reiker. Larry Beal and Paul Rothgery 

of the NPS Denver Service Center provided cost 

estimation guidelines and administered the AML 

inventory contract for the three eastern regions 

and portions of Pacific West Region. The field 

inventory for California NPS units was conducted 

by David Tibor and Jon Mistchenko, with data 

coordination provided by Sarah Reeves. Copyediting and layout services were provided by Schatz 

Publishing Group.

Finally, we thank our panel of subject-matter 

experts who provided peer review of this report: 

Mike Garner, Mark Mesch, Sara Newman, andGeorge Stone.

Acronyms

AKR NPS Alaska Region

AML Abandoned Mineral Lands

AMLAC Abandoned Mineral Lands

Advisory Committee

ARRA American Recovery and

Reinvestment Act of 2009

BLM Bureau of Land Management

DOI Department of the Interior

IMR NPS Intermountain Region

FMSS NPS Facilities Management 

Software System

FY Fiscal Year (federal government 

fiscal year is October 1 through 

September 30)

MWR NPS Midwest Region

NCR NPS National Capitol Region

NER NPS Northeast Region

NPS National Park Service

OIG Office of the Inspector General, 

Department of the Interior

PUF Polyurethane Foam

PWR NPS Pacific West Region

SER NPS Southeast Region

SERI Society for Ecological Restoration 

International

USGS U.S. Geological Survey
 National Park Service vii

Terms

AML Abandoned Mineral Lands (AML) are lands, waters, and surrounding watersheds 

that contain facilities, structures, improvements, and disturbances associated with 

past mineral exploration, extraction, processing, including oil and gas development, and transportation operations for which there is no nonfederal owner or 

viable responsible party.

Ecological 

Restoration

The process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed. The goals of restoration are the re-establishment of the preexisting biotic integrity in terms of species composition and community structure. 

(Society for Ecological Restoration International (SERI), 2004 )

Features Individual elements of an AML site, such as vertical shafts, adits, open stopes, open 

pits, highwalls, and prospects; structures such as headframes, mills, wellheads, and 

storage facilities; landform modifications such as access roads, drainage diversions, 

and drill pads; and piles of ore, protore (marginal-grade ore), waste rock, soil stockpiles, and hardrock or placer tailings. For a detailed listing of AML features and 

their definitions, see appendix A.

Mitigation Any action intended to avoid, reduce, or eliminate hazards or environmental damage. (SERI, 2004) This includes gating, plugging, and reclaiming an AML site or 

feature that requires remedial action. Many programs use this term to convey only 

temporary remedial measures such as posting warning signs or installing fencing, 

but throughout its history, the NPS AML Program has used the broader definition 

for mitigation.

NPS Unit A distinct area of land or water set aside for protection by Congress as part of the 

National Park System. Included in the NPS are designations such as national park, 

national monument, national historic site, national preserve, national recreation 

area, and national river.

National Park 

System

The system of lands comprised of 399 individual NPS units as of the date of this 

report. The National Park Service preserves unimpaired the natural and cultural 

resources and values of the national park system for the enjoyment, education, and 

inspiration of this and future generations.

Reclamation Stabilization of the terrain, assurance of public safety, aesthetic improvement, and 

usually a return of the land to what, within the regional context, is considered to be 

a useful purpose. (SERI, 2004)

Rehabilitation The reparation of ecosystem processes, productivity, and services. (SERI, 2004)

Remediation Similar to mitigation; remediation always implies more permanent measures taken 

to avoid, reduce, or eliminate hazards or environmental damage. This includes 

“treatments” such as gating, plugging, reclaiming, and long-term water treatment.

Revegetation Establishment of one or more plant species. Reclamation projects that are more 

ecologically based, including revegetation qualify as rehabilitation or restoration 

projects. (SERI, 2004)

Sites Lands, waters, and surrounding watersheds that contain facilities, structures, improvements, and disturbances associated with past mineral exploration, extraction, 

processing, and transportation operations.

Treatment A specific remedial measure. (See “Remediation”)

Also, see chart and diagram in appendix A: NPS AML feature types and descriptions. 
 National Park Service 1

Introduction

This report presents the interim results of a System-wide National Park Service (NPS) inventory 

and assessment of its Abandoned Mineral Lands 

(AML)1

, conducted from fiscal year (FY) 2010 

through FY 2012. This project has two primary 

objectives: 

● Complete a comprehensive inventory of AML 

sites in units of the National Park System that 

categorizes high, medium, and low priority 

mitigation needs; and 

● Estimate the resources needed to address 

priority issues with NPS AML features using a 

consistent, credible approach. 

By addressing these two main objectives, this 

report responds to key issues raised by the Office 

of the Inspector General (OIG) in its July 2008 

Audit Report: Abandoned Mine Lands in the 

Department of the Interior (DOI, 2008). The OIG 

report found that there is a substantial workload 

in national parks to address hazards and reclamation issues, and that the NPS needs to provide an 

updated assessment of program funding needs.

This report also addresses direction from the 

NPS Director’s October 2, 2008, memorandum to 

regional and associate directors, entitled Mitigating High-Risk Abandoned Mine Land Features 

(Bomar 2008). This memorandum, written in 

response to the 2008 OIG report, directed the NPS 

to update the NPS AML inventory and to identify 

the funding needed to address priority NPS AML 

features.

This AML inventory and assessment report 

presents the results of a three-year coordinated 

effort by the National Park Service Washington 

Office, Natural Resources Stewardship and Science 

Directorate, Geologic Resources Division, the NPS 

Abandoned Mineral Lands Advisory Committee 

(AMLAC, representing all seven NPS regions), 

the NPS Denver Service Center, and the 129 parks 

known to have AML sites within their boundaries. 

Inventory of the California NPS units is underway 

under a contract with the California State AML 

Unit, funded through the American Recovery and 

Reinvestment Act of 2009 (ARRA). The California 

data collected to date are included in this interim 

report and it is estimated that the California inventory is approximately 54% complete.

The NPS is issuing this interim report to highlight 

the large number of high priority sites in need of 

remedial action and in order to proceed with AML 

Program planning. When the California inventory 

is complete in late FY 2013, the NPS projects that 

AML features in California parks may account for 

as many as 80% of the System-wide AML features. 

Upon completion of the California ARRA AML 

inventory, the NPS will update the data and analyses and issue a final AML Inventory & Assessment 

Report.

 The NPS AML Program increases visitor awareness, appreciation, and safety while protecting 

park resources, and thereby complies with the NPS 

mission: “to conserve the scenery and the natural 

and historic objects and the wild life therein and 

to provide for the enjoyment of the same in such 

manner and by such means as will leave them unimpaired for the enjoyment of future generations” 

(NPS 1916 Organic Act). 

1 The NPS AML program includes features from all types of mineral development, including oil and gas. Therefore, the NPS uses the term “Abandoned Mineral Lands.”
2 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

Background

Abandoned Mineral Lands in Parks

Historically, mining and oil and gas companies 

have explored for and extracted a wide variety of 

metals, minerals, and fossil fuels from lands that 

are now part of the National Park System. Precious 

metals, such as gold, silver, and platinum, and base 

metals such as copper, lead, and zinc have been extracted. Industrial minerals such as talc, limestone, 

and borates; and aggregate, mostly sand and gravel, 

have also been mined. Coal mining has occurred 

on parklands. Oil and gas development has occurred in over a dozen park units. 

Most mineral commodities have been developed 

on NPS lands in the distant past. Abandoned sites 

and features are remnants of these activities. Mining and oil and gas sites were abandoned by their 

original operators at a time when reclamation was 

not required by federal and state laws or regulations. Now, reclamation prior to abandonment 

is required by agency regulations that implement 

federal laws such as the Mining in the Parks Act of 

1976, the Federal Land Policy and Management 

Act of 1976, and the Surface Mining Control and 

Reclamation Act of 1977. Individual state laws and 

regulations also require reclamation but vary from 

state-to-state.

For a list and description of the kinds of AML 

features found in the NPS AML inventory, see 

appendix A. Figure 1 shows the distribution of 

AML features in the NPS. The most common AML 

features are adits (horizontal underground openings: 3,191 in the NPS inventory), shafts (vertical 

or near-vertical underground openings: 1,831 in 

the NPS inventory), and quarries and pits (1,482 in 

the NPS inventory). 

Most AML features are located in the Pacific West 

Region – particularly in Death Valley National 

Park, Mojave National Preserve, and Lake Mead 

National Recreation Area, where mostly precious 

metals, base metals, and industrial minerals were 

extracted. The Intermountain Region has similar 

commodities, as well as uranium and oil and gas. 

Abandoned coal mines dominate the Northeast 

Region. The primary commodities in the Southeast 

Region are coal, oil, and gas. The AML features in 

Figure 1. Distribution of 23,182 AML features in NPS units.
 National Park Service 3

the Midwest Region were mostly for developing 

base metals, oil, and gas. The Alaska Region has 

very significant precious and base metal mines. All 

regions have sand, gravel, and rock quarries and 

pits.

Abandoned Mineral Land Hazards and 

Impacts

Nationally, the principal cause of deaths at AML 

sites is drowning in water-filled quarries and pits 

due to the presence of rock ledges, old machinery, 

and other hazards that may be hidden beneath 

the water’s surface.2

 The water can be deceptively 

deep and dangerously cold; and steep, unstable, 

slippery walls make exiting these features extremely difficult. The second most common cause of 

AML deaths and serious injuries is from falls into 

vertical features such as shafts and open stopes 

at abandoned underground mines. Other risks to 

human health and safety include deadly gases and 

radioactive air trapped in confined spaces underground, unstable structures prone to collapse, 

steep and unstable pit highwalls, and explosives 

carelessly discarded by mining operations. 

Abandoned mineral lands pose a risk not only to 

humans, but it is widely known that they can also 

have detrimental effects on the natural environment.3

 Contaminants from the mined materials 

may be released, affecting air, soil, and water quality, as well as plant and animal health. Interruption 

of natural drainage by excavations or emplacement of tailings and waste rock piles can lead to 

extensive erosion and destabilization of the natural 

topography on-and off-site. An AML site can also 

affect the natural beauty of an area, although this 

impact may be an integral part of a historic or cultural landscape in a given park. 

2

 http://www.msha.gov/sosa/fatalstats.asp, http://www.msha.gov/sosa/previousfatalstats.asp 

3

 http://www.abandonedmines.gov/ep.html, http://www.osmre.gov/aml/aml.shtm
4 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

AML Inventory and Assessment Methods 

Early centralized efforts to inventory AML features 

began in 1983, when NPS issued a questionnaire to 

parks requesting basic information about known 

AML sites. NPS replaced this questionnaire in the 

early 1990s with a more extensive field inventory 

form that queried for detailed site location, characterization, and prioritization information needed 

to develop Service-wide mitigation strategies. 

Concurrently, the legacy data and new data were 

compiled in a rudimentary database. That database 

underwent several modifications until the existing 

NPS AML database was developed in 2009.

The abandoned mineral land inventory includes 

sites and features. AML sites include lands, waters, 

and surrounding watersheds that contain facilities, structures, improvements, and disturbances 

associated with past mineral exploration, extraction, processing, and transportation operations. 

AML features are individual elements of an AML 

site, such as vertical shafts, adits, open stopes, 

open pits, highwalls, and prospects; structures 

such as headframes, mills, wellheads, and storage 

facilities; landform modifications such as access 

roads, drainage diversions, and drill pads; and piles 

of ore, protore, waste rock, soil stockpiles, and 

hardrock or placer tailings. For a detailed listing of 

AML features and their definitions, see appendix 

A.

The NPS AML inventory has been systematically 

prepared by AML specialists4

 using the following 

methodology:

● Potential abandoned mineral lands are identified on U.S. Geological Survey (USGS) topographic maps, through field investigations, or 

through previous inventories.

● Park staff or contractors conduct site visits; 

collect GPS coordinates, measurements, and 

other data listed in table 1; and photograph the 

sites and features. 

● In this inventory, a mobile field inventory tool 

is used to edit, update, and transfer AML site 

and feature information directly to and from 

the NPS AML database. This streamlines and 

standardizes all data entry and eliminates potential human errors inherent to transferring 

data from notebooks and field data sheets to 

the database. 

● Features that are mitigated are noted in the 

inventory database, and—where data are available—the date, type, and specific costs of the 

mitigation measures are also included. 

● Mitigation specifications and cost estimates are 

compiled by the team that conducts the field 

inventory so that they reflect existing, on-theground conditions and needs. 

● Data are extracted from the AML database 

using queries that summarize and prioritize the 

inventory data. 

The Service-wide AML database resides on the 

NPS intranet and is available only to NPS users.5

 

Because of the sensitivity of safety and resource 

information and inclusion of government cost estimates for closures in the AML database, the NPS 

only posts summary information on its publicfacing AML website.6 

For this inventory and assessment project, 

AMLAC representatives collaborated to determine 

how to allocate staff and contractors to conduct 

the AML inventory and assessment project in 

their respective regions. As a result, they used 

multiple approaches to gather the inventory data, 

depending upon the availability, capabilities, and 

expertise of park and regional staff. Following is a 

summary of how each region conducted its AML 

inventory: 

● Northeast , National Capital, Southeast, and 

the Pacific West Region outside of California 

and Nevada NPS Units used a contract administered through the NPS Denver Service 

Center. 

● Alaska and Midwest regions, Great Basin 

National Park, Lake Mead National Recreation 

Area, and the Nevada portion of Death Valley 

4

 An AML specialist is a person trained in some aspect of the natural sciences with a solid working knowledge of 

exploration and mining methods, equipment, and impacts. Survey teams usually have several members, each 

with their own area of expertise. 

5

 http://insidemaps.nps.gov/, available only to those inside the NPS firewall with editing rights. 

6

 http://nature.nps.gov/geology/aml, available to the public. 
 National Park Service 5

National Park inventoried their AML resources with regional and/or park staff, sometimes 

assisted by term and seasonal employees, and a 

variety of contracts and/or cooperative agreements with local agencies. 

● Intermountain Region used two approaches to 

complete its inventory. Contractors completed 

inventory and assessment at 300 AML sites in 

17 parks, which included assessing their historical significance. Also, park staff reviewed, 

updated, and collected new data throughout 

the region. 

● Pacific West Region California NPS Units

have been, and will continue to be inventoried 

through FY 2013 under a separate ARRAfunded cooperative agreement with the State 

of California Department of Conservation, 

Office of Mine Reclamation, Abandoned Mine 

Lands Unit.

Table 1. Data collected for NPS AML inventory

CATEGORY FIELDS IN DATABASE

SITE -SPECIFIC

General

NPS region, NPS park code, site name, site type, state, county, congressional district, 

watershed, site acres, land ownership status, administrative use*, NPS Facilities 

Management Software System (FMSS) location ID, FMSS asset priority index, FMSS 

facility condition index, CERCLIS #, EDL #, general site notes

Geologic Resources general commodity, specific commodity, geology notes

Natural Resource Impacts

natural resource impacts significant*, effluent*, water pooling*, water running through 

tailings*, mineral staining on soils/rock*, sediment transport to surface waters*, 

vegetation health, total waste rock volume, visibility to visitors, other impacts, natural 

resource impact notes

Cultural Resources

cultural resource values significant*, National Register listing or nomination*, Cultural 

Landscape designation*, eligible for National Register listing*, site interpreted (signs/

pamplets)*, cultural values notes

FEATURE-SPECIFIC

Identification / Status - General NPS Service-wide identification code, park-specific identification code, feature type, 

action required*, data source, latest revision date, general feature notes 

Access access method, distance from drivable road, distance from established path, published 

information*, designated wilderness*, evidence of visitation, access notes

Geographic Description

USGS quadrangle map name, latitude north (NAD83), longitude west (NAD83), 

elevation, location accuracy, GPS date, slope aspect, within park boundary*, UTM north, 

UTM east, UTM zone, meridian, township, range, section, quadrant

Dimensions dimension X (width), dimension Y (height), depth, depth unknown*, disturbed area, 

disturbed area length, disturbed area width

Biological Resources significant biological resources*, threatened/endangered species present*, other species 

of concern*, bat presence/evidence*, biology notes

Hazards

hazards in need of mitigation*, debris present*, highwall present*, rockfall hazards 

present*, falling hazards*, flooded or evidence of previous flooding*, explosives 

present*, contaminated air documented*, subsidence features present/potential*, 

underground fire/evidence*, hazardous substances present*, hazard notes

Mitigation Required - Specific

temporary safety method required, mitigation option 1, option 1 estimated cost, 

option 1 cost estimate year, mitigation option 2, option 2 estimated cost, option 2 cost 

estimate year, NPS Project Management Information System number, FMSS asset ID, 

mitigation required notes

Mitigation Completed - Specific

recovered naturally*, temporary safety method used, date of temporary safety measure, 

long-term mitigation technique used, date of long-term measure, mitigation cost, 

funding source, mitigation agent, partners used, mitigation complete notes.

Sample and Ranking Data

water sample*, effluent pH, background pH, water contamination*, soil sample*, soil 

contamination*, contamination notes, hazard danger rating (0-5), workings extensive*, 

access difficulty rating (0-5), resource importance rating (4/2/0), resource impacts 

severity rating (4/2/0)

Monitoring monitoring date, monitoring observations

* Fields evaluated by Yes/No/Unknown
6 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

Mitigation Techniques for AML Features

During the AML inventory, a preferred mitigation 

option and associated cost for each feature that 

requires mitigation was developed. Treatment of 

large, contaminated AML sites can be expensive; 

therefore, NPS AML mitigation to date has focused on long-term closures of the most hazardous 

features or temporary closures to mitigate hazards 

until funding is available for long-term remediation 

such as gates or reclamation. If the hazard is particularly critical or if the resources are sensitive or 

severely damaged, park superintendents may close 

access to an AML site under an administrative 

order until the safety hazards or resource impacts 

have been remediated. Mitigation measures used 

to address AML risks vary depending upon site 

conditions, access, and mitigation needs for a given 

feature. Following is a brief list of AML mitigation 

techniques typically used at NPS AML sites: 

● Signs used to prohibit access at AML sites with 

public safety hazards (figure 2)

● Fences ranging from 3-strand wire fences to 

chain-link fences (figure 3) 

● Steel wire or cable nets for treating large 

mine openings or areas of potential subsidence 

(figure 4)

● Earthen backfills to fill open voids; often preferred when wildlife habitat or historic significance are not primary considerations (figure 5)

● Polyurethane foam (PUF) plugs used as 

bases for earthen backfill, enabling a large hole 

to be plugged with a relatively small amount of 

material (figure 6)

● Rock or concrete barrier walls often used on 

horizontal mine entrances (figure 7)

● Plugging of oil and gas wells (figure 8)

● Steel gates and grates with or without lockable hatches to allow access when needed 

(figure 9)

● Wildlife-accessible steel gates and cupolas 

to allow free movement of important wildlife 

species such as bats and desert tortoise, with 

or without lockable bars for human access 

(figures 10 and 11)

● Reclamation to stabilize the terrain and return 

it to its approximate original contour, assure 

public safety, provide aesthetic improvement, 

and usually return the land to what, within the 

regional context, is considered a useful purpose (figure 12)

● Removing or neutralizing explosives

(figure 13)

Figure 2 . Administrative closure sign at Keane Wonder Gold Mine, Death Valley National Park California. The 

closure was done in 2008 to close the popular and historic mine site when testing revealed high levels of 

lead and other contaminants in the soils. (NPS photo)
 National Park Service 7

Figure 3. Fencing of large open stopes, El Portal 

Barite Mine, Yosemite National Park, California 

(NPS photo) 

Figure 4. Cable mesh over open stull stope, Skidoo Gold Mine, Death Valley National Park, California (NPS 

photo)
8 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

Figure 5. Backfill of adit with native rock and soils, Rainy Day Uranium Mine, Capitol Reef National Park, Utah 

(NPS photo)

Figure 6. Polyurethane foam plug and backfill with waste rock in progress (left) and after backfill is 

completed (right) in adit, Jones Branch Mine 195, Big South Fork National River and Recreation Area, 

Tennessee/Kentucky (NPS photo)
 National Park Service 9

Figure 7. Native rock and masonry wall under construction 

15 feet inside adit (left), then backfilled with waste rock 

to the entrance (right), Jomac Uranium Mine, Glen Canyon 

National Recreation Area, Utah (NPS photos)

Figure 8. Oil and gas well plugging operation, 

unnamed orphaned well, Big South Fork 

National River and Recreation Area, Tennessee/

Kentucky (NPS photo)

Figure 9. Steel grate installed over vertical shaft, 

Mariscal Mercury Mine, Big Bend National Park, Texas 

(NPS photo)
10 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

Figure 10. Bat cupola installed over vertical shaft, Skidoo Gold Mine, Death Valley National Park, California 

(left - NPS photo); low-profile bat cupola installed over vertical shaft, Rattlesnake Gold Mine, Mojave 

National Preserve, California (right – photo courtesy of David Tibor, State of California)

Figure 11. Bat gate installed in adit, Monte Cristo Zinc Mine 3, Buffalo National River, Arkansas (left – NPS 

photo); bat gate with desert tortoise access at Katherine Access Gold Mine, Lake Mead National Recreation 

Area, Arizona (right – NPS photo)
 National Park Service 11

Figure 12. Pit restoration in process (left, taken August 2010) and after completion (right, taken November 

2012), to return the land to natural conditions; Sand Creek Gravel Pit 7, Great Sand Dunes National Park and 

Preserve, Colorado (NPS photos)

Figure 13. Dynamite found underground at El Cid Mine, later removed by a certified blaster from the local 

sheriff’s department, Joshua Tree National Park, California (NPS photo)
12 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

Prioritization of Individual AML 

Features

One of the primary objectives of this inventory 

and assessment project is to prioritize features that 

require mitigation into high, medium, and low categories. Appendix B includes a description of the 

ranking criteria used in the current AML inventory, and in NPS AML field inventory work done 

since the mid-1990s. In this report, AML features 

that require mitigation are prioritized according to 

the severity of the safety hazards and the intensity 

of impacts to natural and cultural resources. Due 

to the risk of serious accidents at features rated 3 

and above, the NPS ranks all features with a hazard 

rating greater than or equal to 3 as high priorities 

for mitigation. The results of this ranking system 

are shown in figure 14. NPS assigns high, medium, 

and low priority rankings to each AML feature 

according to the following combinations of Hazard 

and Resource Impact values: 

High Priority: Hazard Level of 3, 4, or 5 or 

Resource Impacts of 4; these 

AML features are top priorities for mitigation. 

Medium Priority: Hazard Level of 2 or Resource Impacts of 2.

Low Priority: Remaining features that 

require mitigation. 

Prioritization of AML Sites

Because AML features are generally clustered 

together at well defined and often times complex 

sites, NPS has established a site-level ranking 

system in addition to individually ranking each 

AML feature. Important reasons to prioritize and 

mitigate AML features at the site level include:

Ranking Methodology for AML Features and Sites

● Number of features requiring action – Sites 

with multiple features tend to attract more visitors, increasing the risk of exposure to safety 

hazards. Sites with multiple features also are 

likely to have more resource impacts. 

● Cultural resource values – If an AML property 

is listed on the National Register of Historic 

Places, the listing is usually comprised of the 

entire site, including many or all of its features. 

● Cost savings – The average cost to mitigate 

AML features drops substantially when all 

features at a given site are remediated together, 

primarily because of reduced overall mobilization costs. 

● Less environmental impact – There is considerably less impact on natural and cultural 

resources when all of the features at a site are 

mitigated at the same time. 

● More efficient planning and compliance – Park 

planning and compliance are usually done for 

all features at a given site.

Given these considerations, it is appropriate to 

treat all of the features requiring action at a site 

at the same time rather than just those that are 

highly ranked and then returning later to treat the 

remaining features. The NPS, therefore, uses a site 

prioritization scheme in this report, ranking each 

site according to its highest-ranked feature and 

then applying the same combinations of Hazard 

and Resource Impact rankings used to prioritize 

individual features. During the implementation 

phase, additional criteria such as site access will be 

used to rank AML features to determine how to 

allocate program funding. 

Cost Estimation Procedure for AML Feature Mitigation

Field inspectors estimated mitigation costs for 

each AML feature using field data and a variety 

of cost estimation techniques. Where available, comparable costs from nearby and recently 

completed AML projects were used as proxies. 

Where no comparable costs were available, inspectors made estimates based on an assessment of 

required labor, equipment, materials, and travel, 

with appropriate markups as outlined in appendix 

D. NPS considers the ranking elements shown in 

table B-1 (degree of hazard, extent of workings, 

accessibility, resource significance, and resource 

impacts) in determining the appropriate mitigation 

technique and in calculating mitigation costs. Cost 

estimates may also include pre- and post-closure 

wildlife surveys, construction monitoring to ensure 

compliance with plans and specifications, biological and archeological monitoring during project 

implementation, and project planning and compliance requirements. 
 National Park Service 13

Results

Based on the current AML inventory comprised of 

23,182 features, 2,869 features at 931 sites require 

remedial action, as shown in figure 14 and table 

2. High priority sites comprised of 2,435 features 

will cost approximately $44.9 million to remediate. 

Medium priority sites (218 features) will cost approximately $7.5 million to remediate. Low priority sites (216 features) will cost approximately $3.2 

million to remediate. The total cost for remediation 

of features requiring action currently in the NPS 

database is approximately $55.6 million. Figure 

15 shows the System-wide prioritization and 

costs to mitigate all of the AML features requiring 

mitigation. 

Figure 14 . Distribution of AML features requiring mitigation, breaking out high, medium, and low priority 

features. 

Table 2. Site prioritization results for AML features that require mitigation

Priority

Sites Features

Cost Percentage of Services-wide 

Features

# % # %

HIGH 626 67.2 2,435 84.9 $44.9

million 10.5

MEDIUM 133 14.3 218 7.6 $7.5

million 1.0

LOW 172 18.5 216 7.5 $3.2

million 0.9

TOTAL 931 100.0 2,869 100.0 $55.6

million 12.4
14 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

Figure 15. Costs to remediate high, medium, and low priority AML features, when ranked by site. Percentages 

relate to number of features to be mitigated. 

The regional ranking of AML sites requiring remediation, their priority and remediation costs, and 

the number of features that would be mitigated are 

shown in figure 16 and table 3. The features that 

require mitigation represent 12.4% of the features 

that have been inventoried to date. The majority 

of AML sites and features requiring mitigation 

fall into the high category, where there is a risk of 

serious injury or where there is severe environmental or cultural resource damage. Even though 

the majority of features requiring mitigation are in 

the Pacific West Region, the data collected in this 

inventory indicate that each region has significant 

AML issues where remediation is necessary. See 

appendix C for a park-by-park summary of remediation priorities and costs. 

Figure 16. Prioritization by region of AML features that require mitigation
 National Park Service 15

Table 3. Prioritization by region of AML sites and related features that require mitigation, their rankings, 

and associated costs

Region

(# NPS units 

that have AML 

features)

High Medium Low Total Regional 

Costs

(x $1,000) Sites Features Cost

(x $1,000) Sites Features Cost (x $1,000) Sites Features Cost(x $1,000)

Alaska (13) 29 42 6,342 9 13 2,058 1 1 32 8,432

Intermountain (44) 146 614 13,886 34 60 3,839 109 118 1,741 19,466

Midwest (18) 5 22 83 18 33 239 21 44 640 962

National Capital (3) 2 5 33 0 0 0 0 0 0 33

Northeast (15) 48 121 901 16 20 131 5 6 57 1,089

Pacific West (23) 379 1,593 19,943 42 78 797 36 47 716 21,456

Southeast (13) 17 38 3,690 14 14 434 0 0 0 4,124

Service-wide Totals 

(129 NPS units) 626 2,435 $44.9million 133 218 $7.5million 172 216 $3,186 $55.6million

Completion of California AML Inventory 

The AML inventory and assessment for the Pacific West Region’s California NPS units, funded 

through the ARRA, is scheduled to be completed in 

late FY 2013. The ARRA contract specified that the 

State of California’s AML Unit would inventory 

and record all features found where mine symbols 

appear on USGS 7.5-minute topographic maps. To 

date, they have recorded an average of five AML 

features for each mine symbol, and have inventoried the land around 54% of the USGS map mine 

symbols. The current California parks inventory 

includes 14,428 features, 1,390 of which require 

mitigation at an estimated cost of $10.2 million. 

Those data are included in this interim report. 

Upon completion of the California inventory in 

2013 any additional features and costs will be 

included in the inventory. Refinements and additions to data for other NPS units are also likely to 

increase numbers in the Service-wide AML inventory. The NPS will produce a final report summarizing the completed Service-wide AML inventory. 
16 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

Department of the Interior (DOI). 2008. Audit Report: Abandoned Mine Lands in 

the Department of the Interior. Report CIN-MOA-0004-2007. July 2008. National 

Park Service website. http://nature.nps.

gov/geology/aml/OIG-DOI_AML_AuditFINAL-2008-0717.pdf (accessed October 10, 

2012). 

Bomar, M. A., 2008, Memorandum: Mitigating HighRisk Abandoned Mine Land Features, National 

Park Service, Washington, DC. 

Bureau of Land Management (BLM). 2006. The 

Cooperative Conservation Based Strategic 

Plan for the Abandoned Mine Lands Program. 

Bureau of Land Management website. http://

www.blm.gov/pgdata/etc/medialib/blm/wo/

MINERALS__REALTY__AND_RESOURCE_

PROTECTION_/aml/aml_strategic_plan.

Par.41029.File.dat/AMLStrategicPlanIntroduction.pdf (accessed October 10, 2012). 

Literature Cited

National Park Service, 2011, Cost Estimating Requirements Handbook, http://www.nps.

gov/dscw/upload/CostEstimatingHandbook_2-3-11.pdf.

Society for Ecological Restoration International, 

2004, The SER International Primer on Ecological Restoration, Version 2, October 2004. 

http://www.ser.org/resources/resources-detailview/ser-international-primer-on-ecologicalrestoration

Appendices

Appendix A: NPS AML feature types and 

descriptions

Appendix B: Discussion of AML feature ranking 

criteria considered for prioritization

Appendix C: Summary AML data by region and 

park 

Appendix D: NPS standard construction approach 

to estimating AML mitigation costs
 National Park Service 17

Appendix A: NPS AML feature types and descriptions

Table A-1. Feature types and descriptions used in NPS AML Inventory

NPS Service-wide AML Database – FEATURE TYPES Dimensions as Specified in Database

CODE FEATURE DESCRIPTION Dim_X Dim _Y Depth

Underground Excavations

AD Adit Horizontal (or near-horizontal) entrance to underground mine. No 

hoisting system was required to transport people and equipment or 

to extract ore. Easy to walk in and out.

width height

horizontal 

distance 

into mine

SH Shaft Vertical (or near-vertical) entrance to underground mine. “Cage” 

hoisting system (mine elevator) was necessary to transport people 

and equipment and to extract ore. Climbing is required to get out.

short 

horizontal 

dimension

long 

horizontal 

dimension

vertical distance down 

shaft

IN Incline Sloped entrance to underground mine, mined from the surface usually along the dip of a vein or stratigraphic horizon. Sometimes called 

“decline,” or “declined shaft.” Steep enough that rail-mounted skip 

hoist system was necessary to extract ore. Clambering is required to 

get out.

width height

slope distance into 

mine

TU Tunnel Horizontal (or near-horizontal) underground mine passageway with 

openings to the surface at both ends. width height

horizontal 

distance 

through 

mine

OS Open Stope Linear opening mined from underground to the surface along the 

course of a vein or mineralized zone. short 

horizontal 

dimension

long 

horizontal 

dimension

vertical/

slope distance down 

into stope

VR Vent Raise Vertical (or near-vertical) feature mined from underground to the surface to aid in mine ventilation. Looks identical to a shaft, but there is 

no waste rock pile nearby since it was not mined from the surface.

short 

horizontal 

dimension

long 

horizontal 

dimension

vertical/

slope distance into 

raise

GH Glory Hole Broad opening mined and collapsed from underground – differentiated from “Shaft” in that it is usually has irregular dimensions and 

there is no waste rock pile nearby, since it was not mined from the 

surface. Differentiated from “Subsidence” in that it is completely 

collapsed, exposing underground workings.

short 

horizontal 

dimension

long 

horizontal 

dimension

vertical distance down 

glory hole

SU Subsidence Any subsidence feature resulting from collapse of subsurface mine 

workings. Describe in Feature_Notes field.

short 

horizontal 

dimension

long 

horizontal 

dimension

maximum 

depth

PR Prospect Any mined feature, horizontal to vertical, less than 6 feet deep. (adit or shaft dimensions, as appropriate)

Surface Excavations 

SM Surface Mine Hardrock or coal open pit, open cut, or strip mine; rock quarry, sand 

& gravel pit, cinder pit, borrow pit, etc.

short 

horizontal 

dimension

long 

horizontal 

dimension

vertical 

depth

HW Highwall Vertical or near-vertical wall that results at end of broad excavation 

into a hillside - may require stabilization/mitigation even if surrounding excavation is not fully reclaimed. Differentiated from steep walls 

on all sides of an open pit mine, portal area of an underground 

mine, or steep area uphill from road / bench cut.

width - height

TR Trench Linear surface excavation for conveyance of water, drainage diversion, outcrop exposure, etc. width length depth
18 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

NPS Service-wide AML Database – FEATURE TYPES (continued)

CODE FEATURE DESCRIPTION

Dimensions as Specified in Database

Dim_X Dim _Y Depth

Other Features

WR Waste Rock (aka “spoil pile,” or “spoils.” Waste rock pile also called “dump.”) 

Unmineralized rock mined to expose and access an orebody. Can 

be “overburden” from pit mine that was stripped to get down to 

the ore zone, or barren rock mined underground to access a vein or 

other mineralized zone. Distinguishing characteristics are variable 

rock size and scant mineralization. Waste rock is usually dumped as 

close to the mine as possible to minimize transportation costs.

short 

horizontal 

dimension

long 

horizontal 

dimension

height of 

pile

TA Tailings At hardrock mine sites, tailings have been ground to a consistent 

sand or powder grain size to facilitate metal extraction. The potential 

for residual metals and processing chemicals, as well as fine grain 

size, make hardrock tailings highly susceptible to erosion and leaching of contaminants into the environment. At placer AML sites, this 

term refers to coarse rocks and boulders cast alongside stream channels that were dredged for gold or other commodities, whereas finer 

tailings were most likely washed downstream. Resulting landform 

is unnatural and difficult to revegetate due to absent soil and sandy 

components. 

short 

horizontal 

dimension

long 

horizontal 

dimension

height of 

pile

OP Ore Pile Abandoned pile of high-grade mineralized rock that was set aside 

to be processed, but never made it to the mill. Includes “protore,” 

which is mid-grade material that is set aside awaiting better market 

conditions or processes that would make it economic to process in 

the future.

short 

horizontal 

dimension

long 

horizontal 

dimension

height of 

pile

TS Topsoil 

Stockpile

Topsoil stockpiled on-site for future use in reclamation phase of the 

operation. Usually stripped at beginning of operation from areas 

to be mined or areas to be used for support facilities (e.g., mill site, 

buildings, and pads for ore and equipment storage).

short 

horizontal 

dimension

long 

horizontal 

dimension

height of 

pile

RD Road Road / mine access bench width length -

IM Impoundment Impoundment for water, tailings, ore processing solutions, etc. short 

horizontal 

dimension

long 

horizontal 

dimension

vertical 

distance to 

bottom

EM Embankment Bank, mound, dike, etc., resulting from site clearing, barricading, or 

other ground surface modifications.

short 

horizontal 

dimension

long 

horizontal 

dimension

height of 

pile

BD Building e.g., mill, office, shop, dry (clothing/showering facility), residence, 

etc.

short 

horizontal 

dimension

long 

horizontal 

dimension

height of 

building

ST Structure e.g., headframe, ore storage bin, ore chute, tipple, loadout, pad, 

foundation for equipment or building, etc.

short 

horizontal 

dimension

long 

horizontal 

dimension

height of 

structure

EQ Equipment e.g., ore car, hoist, trommel, generator, compressor, pressure tank, 

storage tank, front-end loader, mucker, bulldozer, drill rig, etc.

short 

horizontal 

dimension

long 

horizontal 

dimension

height of 

equipment

WE Well e.g., oil, gas, geothermal, water (including hand-dug wells, which 

tend to be rectangular, and drilled wells, which a cylindrical). NOTE: 

For drilled wells, record diamater in feet (e.g., 4” = 0.33 feet).

short 

horizontal 

dimension

long 

horizontal 

dimension

depth

diameter 0 (zero) depth

HC Hazmat 

Cache

Hazardous materials cache that is not associated with another 

feature (e.g., hazmat stash inside an adit should be entered as Feature_Type = “Adit”).

short 

horizontal 

dimension

long 

horizontal 

dimension

average 

height of 

pile

AC Artifact 

Concentration

Any pile of historically significant artifacts, e.g., machinery parts, drill 

bits, core samples, empty food cans. Describe in Feature_Notes field.

short 

horizontal 

dimension

long 

horizontal 

dimension

average 

height of 

pile

TP Trash Pile Discrete trash pile worthy of separate GPS location - to be distinguished from general debris scattered around a site or feature.

Also do not confuse with “dump,” which in mining terminology 

refers to a waste rock pile (mined material that was not sent to a 

mill). Describe further in Feature_Notes field.

short 

horizontal 

dimension

long 

horizontal 

dimension

average 

height of 

pile
 National Park Service 19

NPS Service-wide AML Database – FEATURE TYPES (continued) Dimensions as Specified in Database

CODE FEATURE DESCRIPTION Dim_X Dim _Y Depth

EC Explosives 

Cache

Onsite explosives cache that is not associated with another feature 

(e.g., not a small adit that is used for an explosives magazine).

If explosives are present, make note in Feature_Notes field and 

describe further in Haz_Notes field.

short 

horizontal 

dimension

long 

horizontal 

dimension

average 

height of 

pile

Left-overs

OT Other Anything that does not fit above – include description in Feature_Notes field. (as deemed appropriate)

UN Unknown Use only as a placeholder for legacy data where feature type is 

not specified and current staff are not familiar with site. Please 

update next time site is inspected by entering new feature record 

(with specific feature type identified) into database, then delete 

“Unknown” feature record. [This feature type does not show on 

field inventory forms.]

Figure A-1. Diagram illustrating general mining terminology. 
20 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

Appendix B: Discussion of AML feature ranking criteria considered for prioritization

During the AML inventory, the NPS used hazard, access, resource significance, and resource impacts to 

develop feature- and site-specific mitigation recommendations, cost estimates, and priorities (see table 

B-1). These ranking elements are broken out separately so that they can be applied to the specific needs 

of a project or funding source that focuses on one or more of the elements shown below. 

Table B-1. Criteria used in prioritizing NPS AML features for remedial action

NPS AML Program Feature Ranking Criteria PRIORITY

Hazard Rating (possible score: 0 to 5)

5

• Any coal mine

• Vertical shafts, winzes, or underhand collapsed stopes > 6’

• Irrespirable air

• Instantaneous fatal injury could occur due to mine-related hazard

4 HIGH

• Large unstable structures

• Deep pools of water from which it would be difficult to climb out.

• Potential fatal injury could occur

• Major collapse zones

3

• Radiation potential

• Large stopes overhead - seemingly stable

• Highwalls > 10’ drop-off not apparent from above

• Serious injury could occur

2

• Highwalls > 10’ - drop-off apparent from above

• Rubble around but rock is generally stable

• Moderate injury could occur

MEDIUM

1

• Minimal injuries could occur like tripping, bumping head, cutting oneself

• Highwalls < 10’ in area where such drop-offs are common naturally

• Minimal injury possible LOW

0 • No inherent hazards; no injury potential above normal condition

Workings Extensive

Yes Over 500 feet of workings or multiple levels

No Less than 500 feet of workings or single level

Access Rating (likelihood of visitation - possible score: 0 to 5)

5 Good road with mine as the specific destination; car accessible HIGH

4 Good dirt road, but mine is not specific destination

3 Dirt road or path without specific destination; no car access; easy hiking access < 1 mile MED

2 Near a road/path (within 1 mile); Easy hike > 5 miles or moderate hike < 5 miles

1 > 1 mile from road/path; Moderate hike > 5 miles or hard hike < 5 miles LOW

0 Hard hike > 5 miles; site not easily seen

Resource Significance Rating (possible score: 0, 2, or 4)

4 Endangered species present or site is listed on National or Local Historic Register HIGH

2 Species of concern present or site has significant cultural values MED

0 No species of concern present and site has minimal cultural value LOW

Resource Impacts Rating (possible score: 0, 2, or 4)

4 Highly elevated contaminants or greatly altered pH in water/soils; High visual impact HIGH

2 Moderately elevated contaminants or pH alteration in water/soils; Moderate visual impact MED

0 Minimal contaminants or pH alteration in water/soils; Minimal visual impact LOW
 National Park Service 21

● Hazard: Possible ratings are 0, 1, 2, 3, 4, or 5 (5 being the most hazardous). For purposes of breaking 

the analysis into high, medium, and low hazards, break lines were set as follows: high (3-5), medium 

(2), and low (less than 2). 

● Workings Extensive: Possible entries are yes or no. Larger, multi-level mines are more likely to be 

hazardous, more prone to provide wildlife habitat (especially for bat species), and more likely to be 

culturally significant.

● Access: Possible ratings are 0, 1, 2, 3, 4, or 5 (5 being the most accessible) based on easier access being more likely to attract visitors. For purposes of breaking the analysis into high, medium, and low 

accessibility, break lines were set as follows: easy (4-5), moderate (2-3), and difficult (less than 2). 

This system was set up to rank remote features lower in priority than those that are more accessible. 

For reasons discussed below, the NPS has decided not to include access in the prioritization process 

used for this report. 

● Resource Values: Possible ratings are 0, 2, or 4 (4 being most important). This rating can be further 

broken out by cultural and natural resource values based on answers to fields in the site inventory 

forms under those headings, which yields an additional ranking field. 

● Resource Impacts: Possible ratings are 0, 2, or 4 (4 having the most impacts). Impacts usually pertain 

to natural resources, such as contamination of soils or water quality, but may also pertain to cultural 

resources, such as impacts to the viewshed at historic sites. 

Table B-2 shows the distribution of high, medium, and low rankings for the NPS AML features that require remedial action. NPS added the impacts and resources significance fields to the inventory protocol 

much later than the hazard and access fields; consequently, some of the legacy data does not include values for these elements. Where the impacts and resource significance fields were left blank, NPS assumes 

a value of zero.

Table B-2. System-wide summary of individual AML feature ranking elements for features that require 

mitigation.

Parameter High Medium Low Features Requiring 

# features percent # features percent # features percent Mitigation 

Hazard (high >=3) 2,198 76.6 198 6.9 473 16.5

2,869 Impacts 65 2.3 286 10.0 2,518 87.8

Access 609 21.2 1,753 61.1 507 17.7

Resources Significance 451 15.7 1,633 56.9 785 27.4

A sorted list of all features’ cumulative scores might seem to yield a good scheme for prioritizing 

projects, but this simple evaluation does not fully take into consideration program priorities, which is 

why treatment priorities are established by site in this report (see rationale for ranking by site in the 

Prioritization of AML Sites section in the body of this report).

The percentages in table B-2 show that high priority ratings are mostly due to hazards. Due to the risk 

of a serious accident, the NPS determined that hazard ratings of 3 and above should be considered a 

high priority. 

Fewer features have associated resource impacts, but those impacts can be very significant and mitigation can be costly, so resource impacts are a top concern in the NPS ranking scheme. 
22 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

During the AML inventory, accessibility was an important factor considered when ranking individual 

features. Greater visitation typically occurs at sites that are more accessible; however, many remote 

NPS AML sites are also popular destinations for park visitors.7

 NPS staffs have observed that even 

the most remote sites or the deepest parts of underground mines have received significant visitation, 

as evidenced by trash and graffiti. In many cases, the only access to a remote park area is an old mine 

road or trail that has a mine site as the final destination. Remote sites pose a greater risk of serious 

complications and the distance to populated areas increases the complexity and risk of search and 

rescue operations. For these reasons, the NPS determined that access should not be a major factor 

in prioritizing features into high, medium, and low priorities for the purposes in this report. However, accessibility will be considered when ranking one site or project against another during project 

implementation. 

Similarly, the NPS determined that natural and cultural resource significance, while important, should 

not be considered in developing high, medium, and low prioritization in this report. Natural and 

cultural resource significance rankings developed for the inventory are typically not the results of detailed sampling, site characterization, or studies such as Determinations of Eligibility for listing on the 

National Register of Historic Places. Rather, these are initial impressions designed to identify features 

and sites where more detailed assessments are warranted. As more information is gathered, it is likely 

that more of the features will be placed in the medium and high categories for natural and cultural 

resources significance. 

Based on the OIG report’s emphasis on safety and the data in the Service-wide AML database, the 

NPS has decided that prioritization of AML sites and features should be done using hazards and 

resource impacts, resulting in the majority of NPS AML features falling in the high category. This 

ranking scheme is not the same as has been used by other agencies such as the Bureau of Land Management (BLM 2006). After careful consideration, the NPS’ mandate to protect resources while providing for visitor use supports the prioritization scheme used in this inventory and assessment project. 

The following support the NPS ranking methodology:

● The NPS 1916 Organic Act directs the NPS “... to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations.” 

This mandate focuses on preservation and visitor use. 

● Public access on NPS lands is broadly dispersed in developed and remote backcountry sites.8 

NPS is committed to the safety of park visitors to the greatest extent possible,9

 therefore access 

is not considered a primary factor in prioritizing sites into high, medium, and low categories for 

this analysis. Because park visitors go to remote backcountry AML sites, a truly hazardous feature 

should not be ranked as a medium or low priority just because it is remote. 

The rankings provided in this report are for planning purposes only. Flexibility in ranking and project 

selection will be required during project implementation. 

7

 Anecdotal information from AMLAC, park and regional staff. 

8

 Anecdotal information from park and regional staff.

9

 NPS Management Policies 2006, http://www.nps.gov/policy/mp2006.pdf
 National Park Service 23

Appendix C: Summary of AML data by region and park

Table C-1. System-wide summary of individual AML feature ranking elements for features that require mitigation.NPS Unit

Features Sites

Total Costs 

Total

Already Mitigated

Mitigation Required Total

Sites and Associated Features Requiring Mitigation

High Medium Low

# # # # Sites Features Cost ($) Sites Features Cost ($) Sites Features Cost ($)

Alaska RegionBering Land Bridge National Preserve 4 0 0 3 0 0 0 0 0 0 0 0 0 0Cape Krusenstern National Monument 1 0 0 1 0 0 0 0 0 0 0 0 0 0Denali National Park and Preserve 159 37 10 74 3 5 2,471,780 3 5 923,602 0 0 0 3,395,382

Gates of the Arctic National Park and Preserve 54 1 0 17 0 0 0 0 0 0 0 0 0 0

Glacier Bay National Park and Preserve 46 6 4 23 4 4 182,575 0 0 0 0 0 0 182,575Katmai National Park and Preserve 18 2 1 11 0 0 0 1 1 350,000 0 0 0 350,000

Kenai Fjords National Park 50 12 7 14 2 4 650,628 2 3 648,001 0 0 0 1,298,629

Klondike Gold Rush National Historic Park 3 0 0 1 0 0 0 0 0 0 0 0 0 0

Kobuk Valley National Park 21 4 0 5 0 0 0 0 0 0 0 0 0

Lake Clark National Park and Preserve 17 0 3 8 0 0 0 2 3 80,042 0 0 0 80,042Noatak National Preserve 1 0 0 1 0 0 0 0 0 0 0 0 0 0

Wrangell-St. Elias National Park and Preserve 298 43 31 83 20 29 3,037,488 1 1 56,636 1 1 32,020 3,126,144Yukon-Charley Rivers National Preserve 37 3 0 15 0 0 0 0 0 0 0 0 0 0

13 NPS Units - Alaska Totals 709 108 56 256 29 42 $6,342,471 9 13 $2,058,281 1 1 $32,020 $8,432,796Intermountain RegionAmistad Recreation Area 3 0 2 1 0 0 0 0 0 0 1 2 20,000 20,000

Arches National Park 4 0 3 1 1 3 40,000 0 0 0 0 0 0 40,000

Aztec Ruins National Monument 1 1 0 1 0 0 0 0 0 0 0 0 0 0Big Bend National Park 98 23 0 16 0 0 0 0 0 0 0 0 0 0

Big Thicket National Preserve 28 0 8 28 7 7 2,550,000 0 0 0 1 1 250,000 2,800,000Black Canyon of the Gunnison National Park 13 10 0 13 0 0 0 0 0 0 0 0 0 0
24 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System NPS Unit Features Sites Total Costs Total Already Mitigated Mitigation Required Total Sites and Associated Features Requiring Mitigation High Medium Low

# # # # Sites Features Cost ($) Sites Features Cost ($) Sites Features Cost ($)

Black Canyon of the Gunnison National Monument 20 2 6 18 0 0 0 2 2 4,500 4 4 10,500 15,000

Bryce Canyon National Park 2 0 0 2 0 0 0 0 0 0 0 0 0 0Canyonlands National Park 62 11 22 21 3 5 22,000 6 13 57,000 4 4 30,000 109,000

Capitol Reef National Park 62 20 15 14 2 3 13,500 6 11 25,980 1 1 5,000 44,480

Carlsbad Caverns National Park 11 0 0 9 0 0 0 0 0 0 0 0 0 0Chickasaw National Recreation Area 2 0 2 2 2 2 140,000 0 0 0 0 0 0 140,000

Chiricahua National Monument 13 4 0 5 0 0 0 0 0 0 0 0 0 0

Colorado National Monument 10 1 0 9 0 0 0 0 0 0 0 0 0 0Coronado National Memorial 65 59 5 8 2 4 18,000 0 0 0 1 1 5,000 23,000

Curecanti National Recreation Area 7 1 0 6 0 0 0 0 0 0 0 0 0 0Dinosaur National Monument 18 0 1 2 0 0 0 0 0 0 1 1 20,000 20,000

El Malpais National Monument 28 0 27 6 2 11 38,004 4 16 60,000 0 0 0 98,004

Florissant Fossil Beds National Monument

93 0 3 24 3 3 9,000 0 0 0 0 0 0 9,000

Fort Bowie National Historic Site 32 11 10 6 1 10 10,000 0 0 0 0 0 0 10,000Fort Laramie National Historic Site 1 1 0 1 0 0 0 0 0 0 0 0 0 0Fossil Butte National Monument 5 0 0 5 0 0 0 0 0 0 0 0 0 0

Glacier National Park 47 1 25 27 4 6 145,000 5 5 65,000 11 14 206,000 416,000

Glen Canyon National Recreation Area 73 4 1 35 1 1 200 0 0 0 0 0 0 200

Grand Canyon National Park 72 8 15 38 7 11 96,582 4 4 40,522 0 0 0 137,104

Grand Teton National Park 55 0 4 56 1 1 750 1 1 3,000,000 2 2 701,000 3,701,750

Grant-Kohrs Ranch National Historic Site

1 0 0 1 0 0 0 0 0 0 0 0 0 0

Great Sand Dunes National Park and Preserve

29 13 7 4 3 7 35,710 0 0 0 0 0 0 35,710

Guadalupe Mountains National Park 23 10 4 5 0 0 0 0 0 0 3 4 18,100 18,100

John D. Rockefeller, Jr. Memorial Parkway

1 0 0 1 0 0 0 0 0 0 0 0 0 0

Lake Meredith National Recreation Area

2 1 0 2 0 0 0 0 0 0 0 0 0 0
 National Park Service 25

NPS Unit

Features Sites

Total Costs 

Total

Already Mitigated

Mitigation Required Total

Sites and Associated Features Requiring Mitigation

High Medium Low

# # # # Sites Features Cost ($) Sites Features Cost ($) Sites Features Cost ($)

Organ Pipe Cactus National Monument

788 14 408 25 22 405 3,591,409 0 0 0 3 3 12,600 3,604,009

Padre Island National Seashore 2 0 2 2 1 1 400,000 1 1 500,000 0 0 0 900,000

Pecos National Historic Park 1 0 0 1 0 0 0 0 0 0 0 0 0 0Petrified Forest National Park 20 3 5 17 2 5 220,000 0 0 0 0 0 0 220,000Petroglyph National Monument 3 2 1 3 1 1 40,000 0 0 0 0 0 0 40,000

Rocky Mountain National Park 53 0 1 49 0 0 0 0 0 0 1 1 12,000 12,000Saguaro National Park 541 198 127 177 75 122 6,454,572 3 4 46,330 1 1 4,000 6,504,902

Timpanogos Cave National Monument 3 0 3 3 3 3 24,000 0 0 0 0 0 0 24,000

Tuzigoot National Monument 1 0 0 1 0 0 0 0 0 0 0 0 0 0White Sands National Moument 4 0 2 3 2 2 34,000 0 0 0 0 0 0 34,000

Wupatki National Monument 19 0 12 15 0 0 0 1 1 23,884 7 11 87,300 111,184

Yellowstone National Park 85 9 69 84 1 1 3,000 0 0 0 68 68 359,400 362,400

Zion National Park 28 0 2 27 0 0 0 1 2 16,000 0 0 0 16,000

44 NPS Units - Intermountain Totals 2,429 407 792 774 146 614 $13,885,728 34 60 $3,839,216 109 118 $1,740,900 $19,465,844Midwest RegionApostle Islands National Lakeshore 4 2 0 4 0 0 0 0 0 0 0 0 0 0Badlands National Park 1 0 0 1 0 0 0 0 0 0 0 0 0 0

Buffalo National River 361 6 62 48 5 22 83,100 6 11 89,550 6 29 218,800 391,450

Cuyahoga Valley National Park 18 0 15 18 0 0 0 0 0 0 15 15 421,304 421,304

Fort Union Trading Post National Historic Site 3 0 0 3 0 0 0 0 0 0 0 0 0 0

George Washington Carver National Monument 5 3 0 1 0 0 0 0 0 0 0 0 0 0

Hopewell Culture National Historic Park 3 0 0 1 0 0 0 0 0 0 0 0 0 0

Indiana Dunes National Lakeshore 6 0 0 2 0 0 0 0 0 0 0 0 0 0

Isle Royale National Park 36 7 0 14 0 0 0 0 0 0 0 0 0 0Ozark National Scenic Riverways 1 0 0 1 0 0 0 0 0 0 0 0 0 0

Pictured Rocks National Lakeshore 2 0 0 2 0 0 0 0 0 0 0 0 0 0
26 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System NPS Unit Features Sites Total Costs Total Already Mitigated Mitigation Required Total Sites and Associated Features Requiring Mitigation High Medium Low

# # # # Sites Features Cost ($) Sites Features Cost ($) Sites Features Cost ($)

Saint Croix National Scenic Riverway 20 2 1 12 0 0 0 1 1 1,000 0 0 0 1,000Scotts Bluff National Monument 4 0 4 1 0 0 0 1 4 28,000 0 0 0 28,000

Sleeping Bear Dunes National Lakeshore 15 2 13 9 0 0 0 7 13 103,000 0 0 0 103,000Theodore Roosevelt National Park 2 0 0 2 0 0 0 0 0 0 0 0 0 0Voyageurs National Park 20 5 4 15 0 0 0 3 4 17,000 0 0 0 17,000

Wilson’s Creek National Battlefield 3 0 0 1 0 0 0 0 0 0 0 0 0 0Wind Cave National Park 1 0 0 1 0 0 0 0 0 0 0 0 0 018 NPS Units - Midwest Totals 505 27 99 136 5 22 $83,100 18 33 $238,550 21 44 $640,104 $961,754

National Capital RegionChesapeake & Ohio Canal National Historical Park 38 9 5 3 2 5 32,811 0 0 0 0 0 0 32,811

National Capitol Parks - East 4 0 0 4 0 0 0 0 0 0 0 0 0 0Prince William Forest Park 11 0 0 1 0 0 0 0 0 0 0 0 0 03 NPS Units - National Capital Totals 53 9 5 8 2 5 $32,811 0 0 $0 0 0 $0 $32,811

Northeast RegionAcadia National Park 12 0 0 12 0 0 0 0 0 0 0 0 0 0Allegheny Portage Railroad National Historic Site 28 1 3 6 1 2 16,980 1 1 5,317 0 0 0 22,297

Appalachian National Scenic Trail 5 0 3 1 1 3 41,838 0 0 0 0 0 0 41,838

Cape Cod National Seashore 1 0 0 1 0 0 0 0 0 0 0 0 0 0

Colonial National Historical Park 1 0 1 1 0 0 0 0 0 0 1 1 30,000 30,000

Delaware Water Gap National Recreation Area 56 3 3 38 2 3 16,188 0 0 0 0 0 0 16,188

Fredericksburg and Spotsylvania County Battlefields Memorial National Military Park

4 2 1 3 0 0 0 0 0 0 1 1 7,031 7,031

Friendship Hill National Historic Site 5 3 1 3 0 0 0 1 1 510 0 0 0 510

Gauley River National Recreation Area 39 0 21 5 5 21 120,295 0 0 0 0 0 0 120,295

New River Gorge National River 696 124 105 122 39 92 705,240 10 13 39,961 0 0 0 745,201
 National Park Service 27

NPS Unit

Features Sites

Total Costs 

Total

Already Mitigated

Mitigation Required Total

Sites and Associated Features Requiring Mitigation

High Medium Low

# # # # Sites Features Cost ($) Sites Features Cost ($) Sites Features Cost ($)

Richmond National Battlefield Park 2 0 0 2 0 0 0 0 0 0 0 0 0 0Saratoga National Historical Park 1 0 0 1 0 0 0 0 0 0 0 0 0 0Shenandoah National Park 27 2 8 17 0 0 0 4 5 85,454 2 3 20,105 105,559

Steamtown National Historic Site 1 0 0 1 0 0 0 0 0 0 0 0 0 0Valley Forge National Historical Park 9 2 1 7 0 0 0 0 0 0 1 1 0 015 NPS Units - Northeast Totals 887 137 147 220 48 121 $900,541 16 20 $131,242 5 6 $57,136 $1,088,919Pacific West RegionCity of Rocks National Reserve 15 4 2 8 0 0 0 2 2 16,948 0 0 0 16,948

Crater Lake National Park 15 0 5 15 0 0 0 5 5 23,306 0 0 0 23,306

Craters of the Moon National Monument and Preserve 53 43 0 5 0 0 0 0 0 0 0 0 0 0Death Valley National Park 9,250 54 809 201 146 802 11,205,312 1 4 0 2 3 0 11,205,312Golden Gate National Recreation Area 11 0 0 3 0 0 0 0 0 0 0 0 0 0Great Basin National Park 281 38 93 15 5 69 609,500 3 23 486,500 1 1 12,000 1,108,000

Joshua Tree National Park 531 20 58 64 23 53 311,100 3 4 0 1 1 200 311,300

Lake Chelan National Recreation Area 8 2 0 8 0 0 0 0 0 0 0 0 0 0Lake Mead National Recreation Area 1,102 74 146 419 44 81 947,187 20 28 211,600 30 37 697,901 1,856,688

Lassen Volcanic National Park 1 0 0 1 0 0 0 0 0 0 0 0 0 0

Lava Beds National Monument 10 0 0 4 0 0 0 0 0 0 0 0 0 0

Mojave National Preserve 6,460 302 537 253 131 534 6,425,588 3 3 0 0 0 0 6,425,588

Mount Rainier National Park 48 2 5 32 0 0 0 0 0 0 2 5 6,000 6,000North Cascades National Park 73 2 13 38 5 9 110,256 3 4 43,922 0 0 0 154,178

Olympic National Park 25 0 7 13 1 2 7,638 2 5 14,583 0 0 0 22,221

Parashant National Monument 12 12 0 1 0 0 0 0 0 0 0 0 0 0

Point Reyes National Seashore 57 0 3 3 2 3 19,000 0 0 0 0 0 0 19,000

Puukohola Heiau National Historic Site 1 0 0 1 0 0 0 0 0 0 0 0 0 0

Redwood National Park 7 4 0 5 0 0 0 0 0 0 0 0 0 0

Ross Lake National Recreation Area 21 2 1 11 1 1 3,732 0 0 0 0 0 0 3,732
28 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System NPS Unit Features Sites Total Costs Total Already Mitigated Mitigation Required Total Sites and Associated Features Requiring Mitigation High Medium Low

# # # # Sites Features Cost ($) Sites Features Cost ($) Sites Features Cost ($)

Sequoia & Kings Canyon National Parks 137 0 20 12 8 20 163,000 0 0 0 0 0 0 163,000Whiskeytown-Shasta-Trinity National Recreation Area 102 20 12 23 10 12 70,000 0 0 0 0 0 0 70,000Yosemite National Park 64 2 7 5 3 7 71,000 0 0 0 0 0 0 71,000

23 NPS Units - Pacific West Totals 18,284 581 1,718 1,140 379 1,593 $19,943,313 42 78 $796,859 36 47 $716,101 $21,456,273

Southeast RegionBig Cypress National Preserve 91 0 0 15 0 0 0 0 0 0 0 0 0 0

Big South Fork National River & Recreation Area 144 48 34 40 10 21 3,448,001 13 13 432,127 0 0 0 3,880,128Chickamauga & Chattanooga National Military Park 1 1 0 1 0 0 0 0 0 0 0 0 0 0

Cumberland Gap National Historical Park 2 2 0 1 0 0 0 0 0 0 0 0 0 0Everglades National Park 17 0 0 17 0 0 0 0 0 0 0 0 0 0Great Smoky Mountains National Park 21 4 11 2 2 11 115,747 0 0 0 0 0 0 115,747

Horseshoe Bend National Military Park 2 0 0 2 0 0 0 0 0 0 0 0 0 0

Jean Lafitte National Historical Park and Preserve 11 7 4 8 4 4 95,244 0 0 0 0 0 0 95,244

Kings Mountain National Military Park 1 1 0 1 0 0 0 0 0 0 0 0 0 0

Mammoth Cave National Park 16 9 0 17 0 0 0 0 0 0 0 0 0 0Natchez Trace Parkway 4 0 1 4 0 0 0 1 1 1,845 0 0 0 1,845Obed Wild & Scenic River 3 0 2 2 1 2 31,432 0 0 0 0 0 0 31,432

Russell Cave National Monument 2 0 0 2 0 0 0 0 0 0 0 0 0 0

13 NPS Units - Southeast Region Totals 315 72 52 112 17 38 $3,690,424 14 14 $433,972 0 0 $0 $4,124,396

129 NPS Units - System- Wide Totals 23,182 1,341 2,869 2,646 626 2,435 $44,878,387 133 218 $7,498,120 172 216 $3,186,261 $55,562,768

(Detailed data reside in the Service-wide AML database. Custom data reports can be generated according to specific region and park needs.)
 National Park Service 29

Appendix D: NPS standard construction approach to estimating AML mitigation costs

NATIONAL PARK SERVICE – DENVER SERVICE CENTER

ABANDONED MINERAL LANDS INVENTORY AND ASSESSMENT 

Overview

The intent of this document is to present the standard construction cost estimating approaches that are 

used for the Eastern, Pacific West, and other regions of the National Park Service for the generation of 

mitigation costs associated with Abandoned Mineral Land (AML) sites and features located in National 

Park Service units. 

Cost Elements to Include and Associated Percentages

Class C estimates represent costs for a project without having the scope of work fully defined. The generally accepted industry accuracy range of Class C Construction Cost Estimates is -30% to +50%.

The cost estimate for mitigation options shown in the AML database should contain the following direct 

cost elements of a Class C cost estimate. These direct costs assume that work will be contracted and not 

completed with park or volunteer resources.

● Labor – Actual estimated costs for labor

● Equipment – Actual estimated costs for equipment (operator costs not included with these costs)

● Materials – Actual estimated costs for materials 

● Travel cost for remote or off-road features

The following markups should also be included with the mitigation cost Class C estimates:

● Location adjustments (location factors, remoteness, Davis-Bacon wage rates specific to location): 

0–20% depending on location

● General conditions (standard and government): 20%

● Historic preservation factor: 5% if applicable, otherwise use zero

● Overhead: 10%

● Profit: 10%

● Contracting method adjustment: 15%

● Construction management: 8% 

● Contingency (design and construction): 10%

● Compliance: 5% or more 

●

The NPS Service-wide AML database assesses costs on an individual feature basis. Undoubtedly, construction efficiencies will be realized by bundling multiple features into each mine closure project, which 

will lower the costs per feature represented here. Construction efficiencies vary based on such things as 

size of the project budget, proximity of the features from one another, and the type of work to be performed. No attempt has been made to estimate an average construction efficiency factor, but cost savings 

will be realized on larger projects. The individual feature costs in this analysis therefore constitute a highend cost estimate. 

All costs are in FY 2012 dollars. Markups shall be applied in the following order: 

$1,000 is used as an example direct cost.
30 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

Table D-1. AML cost estimating mark-ups

Line Cost Type Calculation Total

A Direct costs (labor, equipment, material) Actual estimated costs $1,000.00

B Location Adjustment Direct Costs x 0.10 $100.00

C SUBTOTAL Sum of Lines A and B $1,100.00

D General Conditions Line C x 0.20 $220.00

E Historic Preservation* Line C x 0.00 $0.00

F SUBTOTAL Sum of Lines C, D, and E $1,320.00

G Bond Line F x 0.01 $13.20

H SUBTOTAL Sum of Lines F and G $1,333.20

I Overhead Line H x 0.10 $133.32

J Profit Line H x 0.10 $133.32

K SUBTOTAL Sum of Lines H, I, and J $1,599.84

L Contracting Method Adjustment Line K x 0.15 $239.98

M SUBTOTAL Sum of Lines K and L $1,839.82

N Construction Management Line M x 0.08 $147.19

O Contingency (Design and Construction) Line M x 0.10 $183.98

P TOTAL ESTIMATE FOR MITIGATION Sum of Lines M, N, and O $2,170.99

* Historic preservation costs should only be included when applicable

Compliance is a separate overall program funding request. Because the percentage would vary depending on approach and needs of a region, it is listed separately rather than as a fixed number in the 

chart.

Cost Elements to Exclude

● Inflation escalation

● Assumptions about government furnished materials

● Builder’s risk insurance/performance bond 

● Cost savings resulting from the mitigation of multiple features within a single contract. At this time, 

there is no way to know how funding will be allocated for mitigation.

Estimating Resources

The following resources are recommended for development of mitigation cost estimates:

● National Park Service Cost Estimating Requirements Handbook available at http://www.nps.gov/

dscw/upload/CostEstimatingHandbook_2-3-11.pdf.

● RSMeans and other construction commercial cost indices. 10

● Historical data for AML mitigation (ARRA projects, in-house, other contracted, etc.), which are kept 

by the Denver Service Center, Geologic Resources Division, and the parks and regions that have 

completed this work. All this information should be recorded in the Service-wide AML database. 

10 http://rsmeans.reedconstructiondata.com/?CouponCode=IGOG2001&gclid=CPfiyJKYu7MCFcRU4Aodg2kAog
 National Park Service 31

Definitions

The following definitions can be found in the NPS Cost Estimating Requirements Handbook.

Bonds – A form of security guaranteeing fulfillment of some obligation. In the construction industry, bonds are typically provided by surety companies to project owners. If the contractor does 

not perform according to the terms of the bond, the surety company will pay the project owner 

the amount specified by the bond. 

Compliance Costs – Costs necessary to finance special studies such as Environmental Assessments or other studies/surveys necessary to be complete prior to construction activities.

Construction Management Costs – Costs associated with project management and monitoring 

of the project. These costs may include any special inspections required during construction.

Contingency (design and construction) – Costs associated with unknowns in the project. 

Contracting Method Adjustment – A majority of the construction contracting for the National 

Park Service is not performed using typical low bid procurement processes. As a result, there is 

a limitation on competition for most projects, which tends to have an upward impact on project 

costs. The primary procurement method used by NPS is competitive negotiation where award 

is based on negotiating a price with the most technically qualified contractor. This method may 

typically add 5% or more to the cost of contracting over the lowest-price, competitive bid procurement processes. The NPS also awards many contracts through the Small Business Administration’s 8(a), Service Disabled Veteran, and Hub-Zone programs. These awards may be made on 

either on a limited competitive or sole source negotiated basis. Depending on the procurement 

method chosen, costs can be affected 10–15% or more.

Equipment – Costs associated with operating owned or rented equipment used for construction activities. Mitigation of abandoned mineral land sites/features typically involves some or all 

of the following: welding machines, backhoe, front-end loader, pickup truck, trailers, generators, 

helicopters, and pumps. Hand tools (shovels, picks, drills, etc.) are not typically included with 

equipment costs.

Federal Wage Rate Factor (labor only) – Costs used to adjust the labor costs of an estimate to 

reflect the difference between the location factor, adjusted labor data used to prepare an estimate, 

and the federally mandated Davis-Bacon Act labor rates in effect for the project location.

General Conditions – A set of guidelines that defines many of the rights, responsibilities, and 

limitations of authority of the owner and contractor, and includes the general procedures governing the performance of the work. 

Standard General Conditions – These are the project indirect costs incurred by the contractor 

that are typically defined in the Division 1 specifications for a project. The costs associated with 

temporary utilities, field offices, fencing, field engineering, operation and maintenance manuals, etc., are all included as standard general conditions. Also included in the General Conditions 

percentage should be the cost of construction permits, bonds, and insurance.

Government General Conditions – These costs, which are not included in the Standard General 

Conditions, are the costs of doing work for the United States government and the National Park 

Service. Many of these government costs are attributable to the increased administrative requirements and quality requirements, along with sensitivity to the NPS mission of protecting the cultural and natural resources while allowing the public access and enjoyment thereof.

Historic Preservation Factor – Many projects within the National Park Service involve work in 

and around historical structures or cultural landscapes. It is part of the National Park Service’s 

mission to preserve and maintain the integrity of the original architectural construction, histori-
32 Interim Inventory and Assessment of Abandoned Mineral Lands in the National Park System

cal fabric, and cultural appearance of the assets at or near the proposed work. This requirement 

often creates additional access control issues, protection process requirements, and coordination 

problems during construction, which lead to additional cost impacts to a project. In some cases, 

material costs increase significantly because of the need to select compatible materials. The range 

for this factor can vary significantly, and considerable judgment is required to formulate an appropriate factor. The rationale and justification for the Historic Preservation Factor should be well 

documented in the Basis of Estimate Statement.

Inflation Escalation – Independent government and architectural/engineering company (A/E) 

estimates are generally prepared well in advance of contract procurement. Therefore, some sort of 

factor needs to be applied to an estimate’s total cost to account for a changing market over time. 

All direct unit costs within the estimates should be priced using current (date of estimate) costs. 

An adjustment for inflation is then added to the bottom line total of the estimate. This escalation 

must be based on a careful analysis of current market trends and published construction economics predictions. Escalation should be dated to the proposed mid-point of construction. If historical costs from the park or project location are used to develop the direct costs, it may be necessary 

to escalate the costs from the time in which they were incurred to present values first, and then 

escalate them to the mid-point of construction. 

Labor – Labor costs include the cost for equipment operators, laborers, welders, supervisors, and 

others to complete the scope of work. This does not include overhead labor. Overhead labor is 

included with the overhead markup.

Location Factor – This factor adjusts generic national average cost data to regional or local construction market pricing for labor, material, and/or equipment. If using a local cost database rather 

than national data, a location factor adjustment will not be required. 

Materials – Mitigation of abandoned mineral land sites/features may require the use of metal, 

concrete, PUF, wood, hardware, fencing, soil stabilization, and/or explosives. Material costs include costs for all materials necessary to complete the scope of work.

Overhead – The cost that a contractor has for staying in business. A general contractor has expenses not directly related to the construction of a project but vital to the contractor’s business 

operations. These include fixed overhead (federal and state unemployment costs, Social Security 

tax, builder’s risk insurance, and public liability costs) and variable overhead (Worker’s Compensation insurance, office overhead, etc.).

Profit – The cost or fee that a contractor charges to provide a return on their investment and to 

compensate them for assuming risk on a project. The amount of profit charged is highly variable and dependent on a number of factors, including local market conditions, the size of job, 

the amount of risk associated with the work, the contractor’s total work volume, and the company size. Contractors generally take more profit on a smaller job. One factor often overlooked 

in preparing independent government estimates and A/E estimates is that not only is the general 

contractor entitled to compensation for overhead and profit, but so are any subcontractors or independent installers that they employ to perform the work. Some cost databases include installer 

overhead and profit in a separate column.

Remoteness Factor –A majority of NPS park units are not located in one of the nearly 700 cities 

listed in the RSMeans City Cost Index or in similar indexes. They are remotely located away from 

significant source areas of labor pools, material vendors, and equipment suppliers. Because of 

the remote nature of most national parks, an adjustment typically needs to be made for mobilization/demobilization, labor pool per diem, compensated commute times, and shipping costs of 

materials, as well as less tangible impacts of managing remote operations. If labor, equipment, and 

materials can be delivered to the project site by over-the-road transportation, we generally use a 

remoteness factor of 1% for each 10 miles that the project is located away from the commercial 

center used in determining the location factor. Considerations should also be made for sites that 

are difficult to access (e.g., unimproved roads, backcountry areas, or where water or aerial access 
 National Park Service 33

is required). If a project site is significantly remote from normal vehicle transportation access, 

some attempt should be made to estimate the direct transport costs (pack teams, boat/barge, off 

road vehicles, or helicopters), or estimators can add an allowance cost or other percentage allowance based on their best estimating judgment or professional experience.

State and Local Taxes – Construction contractors for the National Park Service are required to 

pay local and state taxes on material and rental equipment used on the project. Most find the paperwork for exemption cumbersome and simply pass the taxes along to the government.
The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides scientific and other information about those resources; and honors its special responsibilities to American Indians, Alaska Natives, 

and affiliated Island Communities.

NPS 999/119401, January 2013 
National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science 

1201 Oak Ridge Drive, Suite 150 

Fort Collins, Colorado 80525

www.nature.nps.gov

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