Engineering Evaluation/ Cost Analysis, Lancaster...

D r a f t F i n a l

Engineering Evaluation/ Cost Analysis,

Lancaster Mine Summit County, Colorado

Prepared for

U.S. Forest Service Denver, Colorado

November 2013

Prepared by

215 S. State Street, Suite 1000

Salt Lake City, Utah 84111

ES022111114210SLC /EECA DRAFTFINAL iii

Contents

Acronyms and Abbreviations ................................................................................................. vii

1.0 Executive Summary ..................................................................................................... 1-1 1.1 Removal Action Objectives ............................................................................ 1-1 1.2 Removal Action Alternatives ......................................................................... 1-2 1.3 Evaluation of Alternatives ............................................................................. 1-3 1.4 Recommended Alternative ............................................................................ 1-3

2.0 Characterization ........................................................................................................... 2-1 2.1 Background and Description ......................................................................... 2-1

2.1.1 Site Location and Physical Setting ................................................... 2-1 2.1.2 Previous Lancaster Site Investigations ............................................ 2-8 2.1.3 Physical Characteristics of the Study Area ..................................... 2-8 2.1.4 Surrounding Land Use and Populations ...................................... 2-10 2.1.5 Ecological Assessment ..................................................................... 2-11 2.1.6 Meteorology ...................................................................................... 2-13

2.2 Nature of Contamination ............................................................................. 2-13 2.2.1 Concentrations of COCs .................................................................. 2-13 2.2.2 Upper Lancaster ............................................................................... 2-13 2.2.3 Middle Lancaster .............................................................................. 2-13 2.2.4 Lower Lancaster ............................................................................... 2-14 2.2.5 Downstream Sampling .................................................................... 2-14

2.3 Risk Evaluation .............................................................................................. 2-15 2.3.1 Human Health Risk Evaluation Results and Conclusions ......... 2-15 2.3.2 Ecological Effects Assessment Summary ...................................... 2-16

3.0 Identification of Removal Action Objectives ........................................................ 3-1 3.1 Statutory Limits on Removal Actions ........................................................... 3-1 3.2 Identification and Compliance with ARARs ............................................... 3-1 3.3 Determination of Removal Schedule ............................................................ 3-6

4.0 Identification and Analysis of Removal Action Alternatives ............................. 4-1 4.1 Alternative 1—No Action ............................................................................... 4-3 4.2 Alternative 2— Full Site Restoration with Semi-Passive Treatment of ARD4-3 4.3 Alternative 3— Partial Site Restoration with Semi-Passive Treatment of ARD

............................................................................................................................ 4-6 4.4 Alternative 4—Partial Site Restoration with Control of ARD Drainage . 4-7 4.5 Alternative 5—Partial Site Restoration with No Treatment or Control of ARD

Drainage ............................................................................................................ 4-7 4.6 Site Restoration ................................................................................................ 4-8

4.6.1 Suitability of Site Topsoil .................................................................. 4-8 4.6.2 Suitability of Waste Rock to Support Vegetation .......................... 4-8 4.6.3 Amending Waste Rock ...................................................................... 4-9 4.6.4 Removal of Building and Structure Debris ..................................... 4-9

CONTENTS (CONTINUED)

iv ES022111114210SLC /EECA DRAFTFINAL

4.6.5 Drainage Swales .................................................................................. 4-9 4.6.6 Stream Channel Restoration ............................................................ 4-10

5.0 Detailed Analysis of Alternatives ............................................................................. 5-1 5.1 Effectiveness ..................................................................................................... 5-2

5.1.1 Overall Protection of Public Health and the Environment ........... 5-2 5.1.2 Compliance with ARARs and Other Criteria, Advisories, and

Guidance .............................................................................................. 5-3 5.1.3 Long-Term Effectiveness and Permanence ..................................... 5-7 5.1.4 Short-Term Effectiveness ................................................................... 5-8

5.2 Implementability .............................................................................................. 5-9 5.2.1 Technical Feasibility ........................................................................... 5-9 5.2.2 Administrative Feasibility ............................................................... 5-10 5.2.3 Availability of Services and Materials ........................................... 5-10 5.2.4 State and Community Acceptance ................................................. 5-10

5.3 Cost .................................................................................................................. 5-10

6.0 Comparative Analysis ................................................................................................. 6-1

7.0 References ..................................................................................................................... 7-1

Tables

Table 2-1 .................................................................................................................................... 2-12 Threatened, Endangered, and Candidates Species List for Lancaster Mine Site

Table 3-1 ...................................................................................................................................... 3-3 Identification of Potential Applicable or Relevant and Appropriate Requirements

and TBCs

Table 4-1 ...................................................................................................................................... 4-2 Major Components of Alternatives

Table 5-1 ...................................................................................................................................... 5-1 Evaluation Criteria

Table 5-2 ...................................................................................................................................... 5-5 Primary ARARs Invoked by Alternatives Implementation

Table 5-3 .................................................................................................................................... 5-11 Order of Magnitude Cost Estimates for Alternatives

Table 6-1 ...................................................................................................................................... 6-1 Comparative Analysis of Alternatives


ES022111114210SLC /EECA DRAFTFINAL v

Pictures

Picture 2-1: Lancaster Upper Mine—Physical setting of mine ............................................ 2-3

Picture 2-2: Lancaster Upper Mine – Seasonal Drainage Channel of North Morgan Gulch .............................................................................................................................. 2-3

Picture 2-3: Lancaster Middle Mine—Physical setting of mine .......................................... 2-5

Picture 2-4: Lancaster Middle Mine – ARD Channel ........................................................... 2-5

Picture 2-5: Lancaster Lower Mine—Physical setting of mine ............................................ 2-7

Picture 2-6: Lancaster Lower Mine – Marsh area and spring drainage ............................. 2-7

Figures (Located at the end of text) 2-1 Location Map 2-2 Lancaster Mine Current Conditions 2-3 Topography 4-1 Upper Lancaster Alternatives 4-2 Middle Lancaster Alternatives 4-3 Lower Lancaster Alternatives

Appendices A BioChemical Reactor White Paper B Alternative Cost Estimates C Site Visit Report


vi ES022111114210SLC /EECA DRAFTFINAL

THIS PAGE INTENTIONALLY LEFT BLANK

ES022111114210SLC /EECA DRAFTFINAL vii

Acronyms and Abbreviations

4WD 4 wheel drive

°C degree(s) Celsius

°F degree(s) Fahrenheit

µg/L microgram(s) per liter

amsl above mean sea level

AQCC Air Quality Control Commission

ARAR Applicable or Relevant and Appropriate Requirement

ARD acid rock damage

As Arsenic

Ba Barium

BCR Biochemical Reactor

BLM United States Bureau of Land Management

Ca Calcium

CCR Control Commission Regulations

Cd Cadmium

CDPHE Colorado Department of Public Health and the Environment

CDRMS Colorado, Division of Reclamation, Mining and Safety Program

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CFR Code of Federal Regulations

COC contaminant of concern

Cr Chromium

Cu Copper

CWQCD Water Quality Control Commission

cy cubic yard(s)

EE/CA Engineering Evaluation and Cost Analysis

EPA United States Environmental Protection Agency

ESV Ecological Screening Value

ACRONYMS AND ABBREVIATIONS (CONTINUED)

viii ES022111114210SLC /EECA DRAFTFINAL

Fe Iron

ft feet

GPM gallons per minute

HDPE high density polyethylene

Hg Mercury

HHR human health risk

MCL Maximum Contaminant Level

Mg Magnesium

mg/kg milligram(s) per kilogram

mg/L milligram(s) per liter

Mn Manganese

NA not applicable

NCP National Contingency Plan

NE not established

NPDES National Pollution Discharge Elimination System

O&M operation and maintenance

OSHA United States Occupational Safety and Health Administration

PA/SI Preliminary Assessment and Site Inspection

Pb Lead

PM10 particulate matter less than 10 micrometers in aerodynamic diameter

RMC Risk Management Criteria

sq ft square feet

TSV Threshold Screening Value

USFS United States Forest Service

USFWS United States Fish and Wildlife Service

USGS United States Geological Survey

WRCC Western Regional Climate Center

WRNF White River National Forest

yr year

Zn Zinc

ES022111114210SLC /EECA DRAFTFINAL 1-1

1.0 Executive Summary

This Engineering Evaluation and Cost Analysis (EE/CA) was prepared for the Lancaster Mine located in the White River National Forest (WRNF) approximately 0.5 miles northeast of Montezuma, Colorado, in the northwest quarter of Section 25 and southeast quarter of Section 26, Township 5 South, Range 76 West. The United States Forest Service (USFS) authorized the EE/CA under Contract Number AG-82D7-K-13-0002. A Notice to Proceed was signed by the USFS on July 1, 2013. The purpose of the EE/CA is to evaluate various non-time-critical removal action alternatives at the Lancaster Mine in accordance with the National Contingency Plan (NCP) in Part 40 Code of Federal Regulations (CFR) Section 300.415.

The proposed remedial alternatives are largely based on the information that has been provided to date, which includes the Preliminary Assessment & Site Inspection Report for the Lancaster and Tip Top Mines (PA/SI). Contaminants of concern (COCs) identified by the 2011 PA/SI are arsenic, barium, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, silver, uranium and zinc.

As a result of the findings of the PA/SI, the USFS decided to focus interim remedial efforts on the Lancaster Mines to reduce potential hazards to human and ecological receptors. This includes human receptors who may frequent the mine site, including campers and hikers and residences in the area with groundwater wells. Risks to ecological receptors include detrimental impacts on water quality in the North Morgan Gulch. This EE/CA was prepared to evaluate removal alternatives to mitigate these hazards posed by the Lancaster Mine.

1.1 Removal Action Objectives Based upon the findings of the PA/SI and a site visit with the USFS in August 2013, removal action scope and objectives were developed for the three Lancaster Mine sites (Upper, Middle and Lower). The scope is defined in the following sections, and the objectives include the following:

Reduce offsite migration of contaminated sediments from the waste rock piles

Reduce risk to human and ecological receptors from exposure to contaminated water and soil

Attain Applicable or Relevant and Appropriate Requirements (ARARs) to the extent practicable

The focus of the EE/CA is to address all reasonable exposure pathways (soil, surface water, groundwater and direct exposure).

ENGINEERING EVALUATION/ COST ANALYSIS—LANCASTER MINE SUMMIT COUNTY, COLORADO

1-2 ES022111114210SLC /EECA DRAFTFINAL

1.2 Removal Action Alternatives The Lancaster Mine sites share many of the same physical and geologic features including proximity to each other, similar site layout (waste rock dumps on slopes), groundwater issues, proximity to surface water and discharge pathways; therefore, the removal action alternatives were developed to address clean up at all three sites, comprehensively. The removal action alternatives developed and evaluated in this EE/CA are as follows:

Alternative 1—No Action

Leave mine sites as they currently are, with unrestricted access to the site.

Alternative 2—Full Restoration with Treatment of ARD

Excavate the entire waste rock pile from each site, and restore sites to as much as practicable to pre-mining conditions, with slopes matching the natural grade. Treatment of acid rock drainage (ARD) from the Middle and Lower sites prior to discharge to North Morgan Gulch drainage.

Alternative 3—Partial Restoration with Treatment of ARD

Regrade waste rock piles at each site to contour the slopes to more uniform and stable grades, and restore sites with amendments and vegetation, to match natural surroundings. Construct a rock berm at the base of the waste piles on the Upper and Lower sites to provide stabilization of the waste pile and to prevent offsite sediment transport. Treatment of ARD from the Middle and Lower sites prior to discharge to North Morgan Gulch drainage.

Alternative 4—Partial Restoration with Control of ARD

Regrade waste rock piles at each site to contour the slopes to more uniform and stable grades, and restore sites with amendments and vegetation, to match natural surroundings. Construct a rock berm at the base of the waste piles on the Upper and Lower sites to provide stabilization of the waste pile and to prevent offsite sediment transport. Containment and collection of the ARD from the Middle and Lower sites and discharge to North Morgan Gulch drainage.

Alternative 5—Partial Site Restoration with No Control or Treatment of ARD

Regrade waste rock piles at each site to contour the slopes to more uniform and stable grades, and restore sites with amendments and vegetation, to match natural surroundings. Construct a rock berm at the base of the waste piles on the Upper and Lower sites to provide stabilization of the waste pile and to prevent sediment transport to North Morgan Gulch Drainage.

These alternatives also have some form of stormwater control in order to minimize offsite migration of sediment and to route storm water runoff around disturbed areas. Each alternative, except for Alternative 1, also reduces human health and ecological risks to varying degrees by reducing or eliminating contact with waste rock and ARD.



1.3 Evaluation of Alternatives An evaluation of alternatives for effectiveness, implementability, and cost was completed. No one alternative consistently outperformed the others with respect to meeting all the evaluation criteria.

From an effectiveness standpoint, Alternative 2 (Full Restoration with treatment of ARD) was the most comprehensive and could meet the required criteria in a timely fashion and with the greatest reduction in human and ecological risk, although it is the most expensive.

Alternative 3 (Partial Restoration with treatment of ARD) meets the required criteria, is technically and administratively feasible with no shortage of materials and service, although it is more expensive then Alternatives 4 and 5 and does not remove the risk for contact with waste rock like Alternative 2.

Alternatives 4 (Partial Restoration with control of ARD) and 5 (Partial Restoration with no treatment or control of ARD) meet the required criteria. Both are technically and administratively feasible with no shortage of materials and service, although each of these alternatives continues to discharge ARD to the North Morgan Gulch drainage without removing contaminants.

From a total present-worth cost perspective Alternatives 4 (Partial Restoration with control of ARD) and 5 (Partial Restoration with no treatment or control of ARD) were the most cost-effective, not including the No Action alternative. Capital costs were significantly less than for the other alternatives. Long-term operation and maintenance (O&M) requirements for Alternatives 2 and 3 require a higher level of O&M at the site, as required by the treatment of ARD, as compared to Alternatives 4 and 5.

1.4 Recommended Alternative Alternative 4 is the recommended alternative based on evaluation of the effectiveness, implementability, and cost of all the alternatives. Alternative 2 is the most protective alternative but costs significantly more than Alternative 4 and requires ongoing operation and maintenance at a remote location.

Alternative 3 provides for an increase in protection from Alternative 4 with only a slight increase in short term costs. However, Alternative 3 requires increased long term costs associated with ongoing operation and maintenance at a remote location. In the event the maintenance for Alternative 3 cannot be performed when required (weather or other issues), the effectiveness and protection of the alternative will be reduced.

Alternatives 4 and 5 do not provide for the treatment of contaminants prior to discharge to surface water, thus not fully eliminating the risk to human and ecological receptors. Alternatives 4 and 5 do not require long term costs associated with operations and maintenance. Alternative 4 offers increased protection through the reduction of offsite migration of sediments and reduced contact time between surface water and waste rock. Alternative 4 provides for optimum containment and control without require long term operation and maintenance at a remote site.






2.0 Characterization

2.1 Background and Description Colorado has a rich mining history, which dates back to the late 1850s, when prospectors heading west to California were forced to winter in Colorado. By the end of the 1850s, gold had been discovered south of Denver in Cherry Creek. Since 1859, 45 million ounces of gold had been mined from Colorado. Later discoveries of silver ore and lead near what is now the town of Leadville continued to increase mining production throughout Colorado.

2.1.1 Site Location and Physical Setting The Lancaster Mine is an abandoned mine on National Forest System Lands located on the White River National Forest managed by the Dillon Ranger District. Lancaster Mine is located in mountainous topography at an elevations ranging from 10,600 to 11,800 feet above mean seal level (amsl). Lancaster Mine is located on the west slope of Collier Mountain, approximately 0.25 to 0.75 miles northeast of the town of Montezuma, Colorado. The Lancaster mine site consists of three sites, Upper, Middle and Lower Lancaster (Figure 2-1) with the upper site located at timberline and the middle and lower sites located in heavily vegetated areas.

The Lancaster Mine site is located within the North Morgan Gulch drainage basin in the White River National Forest on the western slope of the Continental Divide, northeast of and adjacent to the town on Montezuma in Summit County, Colorado. The North Morgan Gulch drainage is a tributary within the overall Snake River Watershed. Drainage from the Lancaster mine sites flows into North Morgan Gulch, which drains into the Snake River approximately 0.25 miles downstream of the mine site, just west of the town of Montezuma (See Figure 2-1, found at the end of the report). North Morgan Gulch appears to generally drain to the Snake River as groundwater and not as a surface water tributary, except in periods of high flows. The Snake River eventually discharges to Dillon Reservoir, which is used as a drinking water source for Denver.

The Lancaster Mine exists in a subalpine environment near the transition to an alpine tundra at the Upper site, and experiences a cool, wet climate. Because of heavy snowpack, the sites are generally accessible from June through September. Weather in October is variable, with freezing temperatures and snow common. Snowpack typically lasts through late May.

Upper Lancaster Location and Physical Setting The Upper Lancaster site contains a waste rock pile, collapsed mine building debris; and experiences seasonal snowmelt runoff (see Picture 2-1). Approximately 1,671 cubic yards (cy) of waste rock are on the slope1 (TT-206), with erosion rills and an apparent kill/erosion zone below the pile. There is a collapsed building along with an unclosed shaft entrance at the top of the waste rock pile. There has been no previous work done by the USFS or the

1 Referred to as Tip Top Mine waste pile TT-206 in the PA/SI Report (USFS, 2011)



State of Colorado, Division of Reclamation, Mining and Safety Program (CDRMS) to close or decommission the manmade structures at the upper mine site. There is no surface water flow at the upper site, and water discharge occurs only as runoff from snowmelt or rain events. When present, runoff from the upper site flows approximately 1,600 ft through the seasonal drainage of North Morgan Gulch located southwest of the site (see Picture 2-2) where it connects to the Middle Lancaster site.



Picture 2-1: Lancaster Upper Mine—Physical setting of mine

Picture 2-2: Lancaster Upper Mine – Seasonal Drainage Channel of North Morgan Gulch



Middle Lancaster Mine Location and Physical Setting The Middle Lancaster site contains a waste rock pile, waste rock debris, a draining adit, intact cabin, campsite with fire pit and an access road to the campsite (see Picture 2-3). Approximately 4,044 cy of waste rock2 (LL-202) is mounded in the center of site, with the presence of some vegetation and no signs of significant erosion. Additionally, below the waste rock pile is approximately 1,548 cy of a thin layer of waste rock debris3 (LL-203) which varies in color from the main waste rock pile and shows no signs of vegetative growth.

The draining adit (LL-102) is located above the waste rock pile and at the time of the site visit had a continuous discharge rate of approximately 10 gallons per minute (gpm). The ARD flows around the waste rock pile in two separate channels, and eventually infiltrates into the North Morgan Gulch drainage on the northwest corner of the site (see photo 2-4). There has been no previous work done by the USFS or the CDRMS to close or decommission the adit at the middle mine site. The intact cabin appears to remain in good condition and to be maintained. The campsite is easily accessible via a 4-wheel drive (4WD) road and appears to be well maintained with a fire pit.

2 Referred to as Upper Lancaster Waste Pile LL-202 in the PA/SI Report (USFS, 2011) 3 Referred to as Upper Lancaster Waste Pile LL-203 in the PA/SI Report (USFS, 2011)



Picture 2-3: Lancaster Middle Mine—Physical setting of mine

Picture 2-4: Lancaster Middle Mine – ARD Channel



Lower Lancaster Mine Location and Physical Setting The Lower Lancaster site contains two waste rock piles, rail tracks between the two piles, collapsed mine building debris, two closed adits, a marsh area and an access road (see Picture 2-5). The waste rock piles contain approximately 4,116 cy in the upper waste pile4 (LL-200) and 3,456 cy in the lower waste pile5 (LL-201). Neither waste pile shows signs of vegetative growth and the southwestern side of the upper waste pile has been undercut due to erosion. The adits are located on the upper waste pile and were closed by the CDRMS in 2007. There is a collapsed building on the lower waste pile and mine operations debris spread throughout the marsh and lower area of the site, including old train tracks.

Surface water from North Morgan Gulch drains through the center of the site between the upper and lower waste piles, creating a marshy area and coming into contact with waste rock. Additionally, a spring, with a flow rate at the time of the site visit of approximately 10 gpm is present at the toe of the upper waste pile. The drainage from the marsh area and the spring flow to a low spot on the southern side of the lower waste pile, where they meet up with the North Moran Gulch drainage (see Picture 2-6). An access road is located off the 4WD road and enters the Lower Lancaster site at the base of the upper waste pile, to the east of the lower waste pile.

4 Referred to as Lower Lancaster Waste Pile LL-200 in the PA/SI Report (USFS, 2011) 5 Referred to as Lower Lancaster Waste Pile LL-201 in the PA/SI Report (USFS, 2011)



Picture 2-5: Lancaster Lower Mine—Physical setting of mine

Picture 2-6: Lancaster Lower Mine – Marsh area and groundwater seep



2.1.2 Previous Lancaster Site Investigations Lancaster Mine Preliminary Assessment and Site Inspection (USFS, 2011) The Natural Resource Management Internship program conducted a preliminary assessment and site investigation (PA/SI) of the Lancaster and Tip Top Mines in 2011 to assess potential human and ecological receptor threats posed by waste rock exposure and ARD. The goal of the PA/SI was to determine if a release of hazardous substances has occurred at the Lancaster and Tip Top mines, which pose a threat to human health or the environment.

Sampling activities during the PA/SI included surface soil sampling of waste rock, surface water sampling and groundwater sampling. Surface water samples were collected throughout North Morgan Gulch above and below mine waste piles, at the draining adit at Middle Lancaster, at the surface expression of groundwater at Lower Lancaster, and in the Snake River above and below input from the North Morgan Gulch. Groundwater samples were collected from two residential wells that are downstream of the site, near the town of Montezuma. Soil samples from the waste piles were analyzed for total metals and leachable metals. Groundwater and surface water samples were analyzed for total and dissolved metals. Surface water samples were additionally analyzed for major anion analysis.

Results of the PA/SI are presented in Section 2.3.

2.1.3 Physical Characteristics of the Study Area Surface Features The Lancaster Mine site is located in the eastern reaches of the Southern Rocky Mountains within the Physiographic Province (United States Geological Survey [USGS] HA 730-C). The mines are located in a mountainous region with elevations exceeding 11,500 feet amsl. The town of Montezuma, approximately 0.75 miles to the southwest, lies at approximately 10,300 feet amsl in a valley carved out by the drainage channel of the Snake River.

Lancaster Mine Site The steep local topography is shown in Figure 2-3. The upper waste pile slopes to southwest at a grade of 1.25:1, and covers an area of approximately 9,968 square feet (sq ft). At the Middle site, the waste pile (LL-202) covers an area of 4,084 sq ft and slopes mainly to the west at a slope of 1.7:1. The waste rock pile (LL-203) covers an area of 8,960 sq ft and slopes to the west at a grade of 1:0.35. The waste rock at the Lower site has two piles that cover areas of approximately 11,7866 sq ft (LL-200) and 4,809 sq ft (LL-201), respectively. The upper waste pile (LL-200) has an average grade of 1.4:1 and slopes from the southeast to the northwest. The smaller waste pile slopes generally to the southwest, with a slope on the top the pile of about 7:1 and steeper slide slopes.

All three Lancaster sites are accessed via County Road 264, a 4WD road not accessible year round due to snowpack. The Upper Lancaster site is located approximately 0.20 miles north of this road and is accessed via a foot trail. The Middle and Lower sites can be accessed via separate two tracks off of Country Road 264. The Middle Lancaster site sits approximately 1,600 ft to the southwest of the Upper Lancaster site. Lower Lancaster is located approximately 700 ft to the southwest of the Middle Lancaster site. All three sites face to the southwest and are in alignment with the drainage channel for North Morgan Gulch.



Surface Water Hydrology

Drainage. Watershed surface water regimes respond to seasonal patterns, with high flows occurring in the spring (May through June) in response to snowmelt. Low flows typically occur in early fall through late winter (October through February). Occasional summer thunderstorms can create temporary “flashy” peaks defined by rapid increases and decreases in flow rate, but these flows are less likely than a typical spring runoff. Surface water in the North Morgan Gulch Watershed flows southwest, collecting in North Morgan Gulch, which feeds into the Snake River as groundwater just west of the town of Montezuma.

Upper Lancaster Mine Site. Surface water from the site flows into the North Morgan Gulch drainage channel at the southwest corner of the site. At that elevation, the North Morgan Gulch drainage channel is intermittent and only flows when it receives water due to snowmelt or large precipitation events. Surface water from the Upper Lancaster site flows approximately 1,900 ft southwest through the drainage to where North Morgan Gulch becomes a year round stream fed by groundwater springs.

Middle Lancaster Mine Site. Surface water from the Middle Lancaster site includes both ARD from the draining adit and runoff from precipitation events and snowmelt. Surface water from the site flows into the North Morgan Gulch drainage channel at the northwest corner of the site. The draining adit supplies a continuous source of surface water into the drainage channel, however due to the low flow rate and gradual slope of the channel most infiltrates to groundwater prior to reaching North Morgan Gulch. Approximately 200 ft southwest of the site, North Morgan Gulch becomes a year round stream fed by groundwater springs.

Lower Lancaster Mine Site. Surface water from the Lower Lancaster site is comprised of the North Morgan Gulch, a groundwater spring, and runoff from precipitation events and snowmelt. The North Morgan Gulch drainage channel fans out over a relatively flat area though the site between the two waste piles. The North Morgan Gulch contacts waste rock that washed down into the marsh area from the upper pile and flows around the north and south sides of the lower waste pile. Additionally, a groundwater spring, located at the base of the upper pile, flows through the marsh area, where it meets up with the North Morgan Gulch on the south side of the lower pile. The groundwater spring has some discoloration near the source point, indicating it may be ARD. Most of the surface water on the lower Lancaster site flows to the northeast corner of the site, where the North Morgan Gulch drainages continues southwest toward the town of Montezuma. Both the North Morgan Gulch creek and the groundwater spring appear to be continuous year round at the Lower Lancaster site.

Geology The Lancaster Mine sits within the ‘Colorado Mineral Belt’ which runs from the southwest area of the state, near Durango, northeast to the Front Range near Boulder, Co. The mineral belt is the byproduct of hydrothermal fluids that infiltrated a Pre-Cambrian lineament of weakness, which may be the product of ancient continental suture. The deposition of mineral rich deposits occurred during the latter part of the Laramide Orogeny, in the Eocene. The basement of the Montezuma quadrangle is largely Pre-Cambrian rocks including granite, gneiss, and schist. Near the town of Montezuma, a large stock of quartz monzonite invaded the pre-Cambrian rocks during the Laramide Orogeny. Most of the ore



deposits in the Montezuma Mining District are mesothermal veins that strike northeast and dip northwest. Although mining in the area began due to placer gold, most ore veins consisted of lead, zinc and silver ores. Galena, sphalerite, pyrite and quartz are found in most ore deposits within the Montezuma quadrangle (Lovering, 1935).

The geology at the site is largely the Montezuma quartz monzonite stock, which encompasses most of Tip Top Peak. Much of the town on Montezuma, downslope of the site, sits on glacial till and alluvium (Lovering, 1935). Soil cover at the site is most likely part of the Frisco-Peeler complex that exists on 25-65% slopes. These soils are well drained and are found on mountainsides and ridges. This soil is typically covered with duff of littler (needles and twigs), which is underlain by a sandy loam. The Frisco-Peeler complex has a moderate permeability, moderate to high water capacity, and high water erosion capacity (Miles R. and Fletcher L., 1980).

Hydrogeology The hydrology of North Morgan Gulch is the expression of groundwater outflow. Surface Water flow displays significant interconnection between the surface groundwater. This is very apparent adjacent to the middle site (LL-202 and LL-203). Surface water was observed approximately 200 feet downstream of the Middle site. Surface water flow in North Morgan Gulch infiltrates and becomes groundwater before entering the Snake River, and before reaching the town on Montezuma. There is no surface water flow at the Upper site, except during snowmelt and storm runoff. It is assumed that flow from North Morgan Gulch continues to flow down gradient from the site and recharges groundwater in the Snake River valley, but the fault and fracture system of the site and its connection to the groundwater have not been verified.

2.1.4 Surrounding Land Use and Populations The land surrounding the Lancaster sites is mixture of National Forest System lands managed by the WRNF (USFS) and private land ownership. The 2.5-million-acre WRNF is a destination for outdoor enthusiasts and includes hunting, fishing, skiing, backpacking, camping, and motorized vehicle trails (WRNF, 2010). Adjacent southeast of both the Middle and Lower Lancaster sites is a privately owned piece of land. Additionally, there are private lands to the north south and east of the Upper Lancaster site. Along County Road 264 are several privately owned properties that the road passes through. Access to all of the Lancaster sites requires passing through privately owned lands.

Summit County is heavily populated in several areas due to the presence of ski resorts. However, the surrounding area of the Lancaster mine site is sparsely populated, with the town of Montezuma, population of 65, residing approximately 0.25 miles southwest of the site. The town of Montezuma, along with limited residences, is located along the Snake River at the confluence of North Morgan Gulch and the Snake River. Water from the North Morgan Gulch helps recharge the Snake River alluvial aquifers, which is the primary source of drinking water for Montezuma and other downstream residence. Additionally, the Snake River feeds into the Dillon Reservoir, which is used as a drinking water source for the city of Denver.



2.1.5 Ecological Assessment Habitat Characterization and Delineation The lands surrounding the Lancaster mine site is primarily subalpine ecosystems with dense stands of Engelmann spruce, subalpine fir and some lodgepole pine. The understory is defined by sagebrush, fescue and bogsedge. Wildlife that may occur in the subalpine ecosystem includes elk, mule deer, coyote, marmot, pika, black bear, mountain lion, bobcat, red fox, pine marten and various chipmunk species (Fitzgerald et al., 1994). Table 2-1 lists plant and wildlife species with the potential to occur near the mine site that are listed as threatened, endangered or protected (USFWS, 2013 and CPW, 2011). There is no designated critical habitat in Summit County (USFWS, 2013). There are no known occurrences of threatened or endangered species within the site itself.



TABLE 2-1 Threatened, Endangered, and Candidates Species List for Lancaster Mine Site

Common Name Distribution Status

FISH

Bonytail chub Western Colorado Federally Endangered, State Endangered

Colorado pikeminnow Colorado River system Federally Endangered, State Threatened

Greenback cutthroat trout Western Colorado Federally Threatened, State Threatened

Humpback chub Western Colorado Federally Endangered, State Threatened

Razorback sucker Western Colorado Federally Endangered, State Endangered

AMPHIBIANS

Boreal toad Western Colorado State Endangered

Northern leopard frog Statewide State Special Concern

BIRDS

Greater sage-grouse Western Colorado Federal Candidate

Mexican spotted owl Western Colorado Federally Threatened

Yellow-billed cuckoo Western Colorado Federal Candidate

Bald eagle Statewide State Special Concern

American peregrine falcon Statewide State Special Concern

MAMMALS

Canada lynx Western Colorado Federally Threatened, State Endangered

North American wolverine Western Colorado Federally Proposed Threatened, State Endangered

Townsend’s big-eared bat Western Colorado State Special Concern

INSECTS

Uncompahgre fritillary butterfly Western Colorado Federally Endangered

PLANTS

Osterhout milkvetch Western Colorado Federally Endangered

Penland alpine fen mustard Western Colorado Federally Threatened

Aquatic Assessment Overall, the Snake River is a gaining stream with flow characteristics consistent with typical mountain stream flows, although some segments may lose surface water to groundwater. Several tributaries contribute to the flow of the Snake River. The Snake River has been identified as by the Colorado Water Quality Control Division (CWQCD) as a 303(d) impaired segment (CDPHE, 2008). The upper portion and all its tributaries, including North Morgan Gulch, are listed as high priority due to impairments associated with pH, cadmium, copper, lead and zinc. Impairment is caused by both anthropogenic mining sources and naturally occurring acid rock drainage.



2.1.6 Meteorology The town of Breckenridge, Colorado, located approximately 10 miles southwest of Montezuma, has an average annual precipitation of 20.26 inches, including 163.6 inches of annual snowfall. Temperature extremes for the town of Breckenridge range from highs around 75 degrees Fahrenheit (°F) in late summer to lows below 10°F in December and January (WRCC, 2013).

2.2 Nature of Contamination Results of the PA/SI are discussed in this section.

2.2.1 Concentrations of COCs Concentrations of COCs in the waste rock, surface water, and groundwater were determined by collecting samples around the Lancaster Mine sites, including along North Morgan Gulch and the Snake River during the PA/SI. The discussion below provides a summary of findings and the PA/SI should be referred to for further details.

2.2.2 Upper Lancaster The Upper site contains no visible expression of surface or groundwater. At this site, COCs were only found in mine waste materials.

Ag, As, Ba, Cr, Cu, Fe, Mn, Pb, Sr, Ti and Zn were all detected in the mine waste sampled. As and Pb were both detected at levels that exceed human health risks at concentrations of 242 mg/kg and 6,634 mg/kg, respectively. Additionally, As, Ag, Ba, Cr, Cu, Fe, Pb, Mn and Zn were detected at concentrations that present an ecological health hazards. Of the exceedences As, Pb and Zn (1,193 mg/kg) are considered to have medium to extremely high risks for ecological receptors. Potential COCs from leachate of the mine waste include As, Cd, Cu, Pb, Zn, Ba and Cr.

2.2.3 Middle Lancaster The Middle site contains surface water from North Morgan Gulch, groundwater at the definition of the adit, and two separate waste rock piles LL-202 and LL-203.

At the Middle site Ag, As, Ba, Fe, Ni, Pb, Sr, Ti and Zn were detected at both waste piles, Cu and Hg were detected at LL-202 and Mn was detected at LL-203. As and Pb were both detected at LL-202 at levels that exceed human health risks at concentrations of 101 mg/kg and 1,418 mg/kg, respectively. Additionally, Ag, As, Ba, Fe, Hg (LL-202 only), Mn, Ni, Pb and Zn were detected at concentrations that present an ecological health hazard. Of the exceedences As, Pb and Zn are considered to have medium to high risks at LL-202 and low to medium risks at LL-203 for ecological receptors, with concentrations ranging from 21-101 mg/kg, 521-1,418 mg/kg and 1,207-2,597 mg/kg, respectively. Potential COCs from leachate of the mine waste include Al, As, Cu, Fe (LL-202 only), Mn, and Zn.

Groundwater at the site is presented in the form of the draining adit and detected COCs include Al, Ca, Cd, Fe, Mg, Mn, Pb, U and Zn. Of those detected, Fe, a secondary EPA contaminant, is the only COC detected above the EPA MCL or groundwater standard. Cd, Mn, and Zn were all detected at concentrations that present a low to medium health risk to campers and medium to extremely high risk to residents, with total concentrations of 4.23



ug/L, 4,400 ug/L and 2,727 ug/L. Concentrations of Cd, Fe, Mn, Pb, U and Zn in groundwater pose a threat to ecological health.

Surface water at the site is in the form of the North Morgan Gulch drainage, which is a seasonal surface water source that runs adjacent to the north side of the site. Surface water samples were collected both downstream and upstream, and the upstream sample was used as a background. Al, Ba, Ca, Fe, Mg, Mn, and Zn were detected in both surface water samples. Of the COCs detected, none exceeded human health risks. Zn poses a threat to ecological health, at total concentrations of 363.7 ug/L upstream and 818.8 ug/L downstream.

2.2.4 Lower Lancaster The Lower site contains surface water from North Morgan Gulch, groundwater at the definition of the seep, and two separate waste rock piles LL-200 and LL-201.

At the Lower site Ag, As, Cu, Fe, Mn, Pb, Sr, Ti and Zn were detected at both waste piles. As and Pb were detected at both sites at concentrations of 732 mg/kg and 11,896 mg/kg at LL-200 and 582 mg/kg and 7,897 mg/kg at LL-201. These concentrations provide medium to high health risks for campers onsite and extremely high health risks to residents on the site. Additionally, Ag and Zn at concentrations of 184 mg/kg and 5,991 mg/kg at LL-200 and 147 mg/kg and 2,658 mg/kg at LL-201, respectively, present a low to moderate risk to residents. Ag, As, Cu, Fe, Mn, Pb and Zn were detected at both waste piles in concentrations that pose an ecological risk, with concentration of Pb, Cu and Zn presenting a low to moderate risk and As presenting an extremely high risk. Potential COCs from leachate of the mine waste include As (LL-201 only), Cd, Cu, Pb, Zn, Ba and Cr (LL-201 only).

Groundwater at the site is presented in the form of a seep at the base of LL-200 and detected COCs include Al, Ca, Mg, Mn, and Zn. None of the COCs detected exceed EPA MCLs and groundwater standards. Mn and Zn were detected at concentrations that present a low health risk to campers and a medium to high risk to residents, with total concentrations of 214.6 ug/L and 1,459 ug/L, respectively. Concentrations of Al, Mn and Zn in groundwater pose a threat to ecological health.

Surface water at the site is in the form of the North Morgan Gulch drainage, which is a seasonal surface water source that runs adjacent to the north side of the site. Surface water samples were collected both downstream of LL-201 and adjacent to LL-200.Al, Ba, Ca, Mg, Mn and Zn were detected in both surface water samples, along with Cd and Fe in the downstream sample. Of the COCs detected, none exceeded human health risks. Al, Cd, Mn and Zn pose a threat to ecological health downstream of the site, at total concentrations of 175.8 ug/L, 3.05 ug/L, 436.7 ug/L and 1,858 ug/L, respectively.

2.2.5 Downstream Sampling In addition to onsite sampling, groundwater and surface water samples were collected downgradient of the site, near the town of Montezuma. Two residential wells were sampled for groundwater and the Snake River was sampled upstream and downstream of the confluence with North Morgan Gulch.

The two residential wells sampled were adjacent to the Lower site (ER) and downgradient of the site (PH). Al, Ca, Cd, Su, Fe, Mg, Mn, Pb, Se, and Zn were detected in both residential



wells. Of those detected in ER Cd, Fe, Mn, Pb and Zn exceeded EPA MCLs at total concentrations of 18.72 ug/L, 12,420 ug/L, 16,362 ug/L, 53.19 ug/L and 10,272 ug/L, respectively. Fe, Mn and Zn are all considered secondary contaminants by the EPA. Cd and Pb also exceeded the EPA groundwater criteria at well ER. Concentrations at ER of Cd, Mn and Zn present a high to extremely high health risk to residents, while Pb and Se present a lower risk. Of those COCs detected at PH, none exceeded EPA MCL and groundwater criteria. Zn presents a high health risk to residents, while Cu, Mn and Se present a lower risk, at well PH.

Surface water samples collected from the Snake River had detected concentrations of Al, Ba, Ca, Fe, Mg, Mn, and Zn both upgradient and downgradient of the confluent with North Morgan Gulch. Of the COCs detected, Mn, a secondary contaminant, was detected above the EPA MCLs at concentrations of 95.62 ug/L upstream and 90.49 ug/L downstream. Al, Ba, Mn and Zn were detected at concentrations that present an ecological health risk.

2.3 Risk Evaluation 2.3.1 Human Health Risk Evaluation Results and Conclusions A streamlined approach was used for the human health risk (HHR) presented in the PA/SI with the intention of avoiding having to gather unnecessary information. This approach integrated relevant information obtained during the PA/SI to quantify risk to reasonably anticipate current and future human and ecological receptors. This approach considered EPA regulation and guidance, BLM RMCs and the bounds of technical feasibility. Important aspects of this approach included the following:

The COC concentrations in soil samples were compared with BLM-developed Risk Management Criteria (RMC) to evaluate potential health risks posed by COCs to residents and campers.

The COC concentrations in surface water samples were compared to primary and secondary EPA drinking water MCLs. Additionally, COC concentrations in surface water were compared with BLM-developed RMC to evaluate potential health risks posed to campers.

The COC concentrations in groundwater samples were compared to primary and secondary EPA MCLs and groundwater standards. Additionally, COC concentrations in groundwater were compared with BLM-developed RMC to evaluate potential health risks posed to campers and residents.

Table 2-2 gives a summary of the human health screening criteria compared with sampling results from the 2011 PA/SI and includes the source of COCs, exposure routes, contaminant exceedences and threshold criteria.



Table 2-2 Human Health Risk Evaluation – Lancaster Mine

Media Source Receptor Exposure Route

Metals Exceeded Threshold Criteria

Upper Lancaster

Waste Rock TT-206 Human

(Camper) Dermal, Ingestion

As, Pb BLM Camper

Middle Lancaster

Waste Rock LL-202, LL-

203 Human


As, Pb BLM Camper

Groundwater Adit LL-102 Human


Cd, Mn, Zn BLM Camper

Human

(Residential) Dermal, Ingestion Fe, Cd, Mn, Zn

BLM Residential, EPA MCL, EPA

groundwater

Lower Lancaster

Waste Rock LL-200, LL-201

Human (Camper)

Dermal, Ingestion

As, Pb BLM Camper

Human (Residential)

Dermal, Ingestion

Ag, As, Pb, Zn BLM Residential

Groundwater Seep LL-04a Human

(Camper) Dermal, Ingestion Mn, Zn BLM Camper

Human (Residential)

Dermal, Ingestion

Mn, Zn BLM Residential, EPA MCL, EPA

groundwater

NOTES:

EPA MCL – EPA National Primary MCL, MCLG and Secondary MCL (EPA, 2009)

EPA groundwater – EPA National Groundwater Regulations (EPA, 2009)

BLM Human Health RMC (Risk Management Criteria for Metals at BLM Mining Sites, Table 2 [October 2004])

2.3.2 Ecological Effects Assessment Summary A streamlined approach was used to evaluate the potential risk to ecological receptors at the Lancaster Mine site. Information obtained during the PA/SI was used to evaluate the ecological risks within the vicinity of the mine sites. This approach considered US Fish and Wildlife Ecological Screening Values, BLM RMCs, and CDPHE Table Standard Values for the Protection of Aquatic Life. Important aspects of this approach include the following:

The COC concentrations in soil samples were compared with BLM-developed Risk Management Criteria (RMC) and USFWS ESVs to evaluate potential ecological risks posed by COCs.

The COC concentrations in surface water samples were compared with CDPHE TSVs and USFWS ESVs to evaluate potential ecological risks posed by COCs.

The COC concentrations in groundwater samples were compared with USFWS ESVs to evaluate potential ecological risks posed by COCs.



Table 2-3 gives a summary of the ecological screening criteria compared with sampling results from the PA/SI and includes the source of COCs, exposure routes, contaminant exceedences and threshold criteria.

Table 2-3 Ecological Risk Evaluation – Lancaster Mine

Media Source Receptor Exposure

Route Metals Exceeded

Threshold Criteria

Upper Lancaster

Waste Rock TT-206 Ecological Dermal, Ingestion

As, Ag, Ba, Cr, Cu, Fe, Pb, Mn , Zn

BLM Elk, ESV

Middle Lancaster


203 Ecological Dermal,

Ingestion Ag, As, Ba, Fe, Hg,

Mn, Ni, Pb, Zn BLM Elk/ESV

Groundwater Adit LL-102 Ecological Dermal, Ingestion

Cd, Fe, Mn, Pb, U, Zn

ESV, CDPHE TVS

Surface Water

North Morgan Gulch

Ecological Dermal, Ingestion Zn ESV

Lower Lancaster


201 Ecological Dermal,

Ingestion Ag, As, Cu, Fe, Mn,

Pb, Zn BLM Elk/ESV

Groundwater Seep LL-04a

Ecological Dermal, Ingestion

Al, Mn, Zn ESV, CDPHE TVS

Surface Water

North Morgan Gulch

Ecological Dermal, Ingestion

Al, Cd, Zn, Mn ESV

NOTES:

BLM Human Health RMC (Risk Management Criteria for Metals at BLM Mining Sites, Table 2 [October 2004])

ESV – US Fish and Wildlife Service Ecological Screen Values (USFWS, 1999)

CDPHE TVS – Colorado Department of Public Health and Environment Table Standard Values for the Protection of Aquatic Life





3.0 Identification of Removal Action Objectives

This section identifies the objectives of the non-time-critical removal action at the Lancaster Mine Sites. Conditions at the Lancaster Mine warrant the evaluation of removal action alternatives for the protection of human health and the environment. The objectives of the removal action are based on the results of the PA/SI, as well as the requirements in the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and ARARs.

The removal objectives of the Lancaster Mine include the following:

Reduce offsite migration of contamination from the waste rock piles

Reduce risk to human and ecological receptors from exposure to contaminated water and soil

Attain ARARs to the extent practicable

The primary risks at the site are direct exposure to metals through ingestion or dermal contact with waste rock, surface water and groundwater at the site, and sediments migrating offsite to the surrounding land and surface waters.

3.1 Statutory Limits on Removal Actions Section 104 of CERCLA addresses the response authority for releases or threats of releases at a site. The USFS has CERCLA authority and therefore has response authority at the Lancaster Mine sites.

3.2 Identification and Compliance with ARARs Section 121(d) of CERCLA requires remedial actions to comply with ARARs. The ARARs evaluation is a two-part process to determine (1) whether a given requirement is applicable and, if it is not applicable, then (2) whether it is both relevant and appropriate.

1. Applicable requirements are cleanup standards and environmental protection regulations per federal or state law that specifically address a hazardous substance, contaminant, remedial action, location, or other circumstance at a CERCLA site.

2. Relevant and appropriate requirements are cleanup standards and environmental protection regulations per federal or state law that do not directly and fully address a specific hazardous substance, contaminant, remedial action, location, or other circumstance at a CERCLA site but address problems or situations similar to those encountered at the CERCLA site.



CERCLA actions may have to comply with several different types of requirements. For this reason, ARARs are typically divided into three categories, which are defined as follows and then discussed in more detail in the following sections:

1. Chemical-specific ARARs are regulatory health- or risk-associated numerical values that govern acceptable concentration of a chemical in environmental matrices such as soil, groundwater, or air. The most stringent chemical-specific standard should be used in the case of a chemical having more than one requirement, or in the case of a mixture of chemicals, several chemical-specific requirements.

2. Action-specific ARARs are determined according to the specific technologies or activities taking place under each alternative. Each alternative has an individual, distinct list of action-specific ARARs depending on the technologies and activities being implemented.

3. Location-specific ARARs are determined according to site-related characteristics such as geology, floodplains, wetlands, sensitive ecosystems and habitats, and historic places.

Table 3-1 summarizes the potential chemical-, action-, and location-specific ARARs and TBCs identified for the response activities at the Lancaster Mine sites.



TABLE 3-1 Identification of Potential Applicable or Relevant and Appropriate Requirements and TBCs

Description of ARAR AA or RA Reasoning

Chemical Specific ARARS

Safe Drinking Water Act – National Primary and Secondary Drinking Water Regulations, 40 CFR 141 and 142

RA The water in the North Morgan Gulch area of concern is a potential source of drinking water

CWQCD – 5 CCR 1002-31 AA Establishes requirements for restoring and maintaining the quality of surface water (effective January 1, 2011).

CWQCD – 5 CCR 1002-31.11 AA Basic Standards Applicable to Surface Waters of the State. Establishes basic surface water quality standards.

CWQCD – 5 CCR 1002-31.13 AA State Use Classifications. surface water classification based on use, agriculture, aquatic life, domestic water supply, and wetlands.

CWQCD – 5 CCR 1002-33.6 AA Classifications and Numeric Standards for Upper Colorado River Basin and North Platte River (Planning Region 12). North Morgan Gulch drains directly into the Snake River that is included in Segment 6a. These requirements establish segment specific water quality standards for Segment 6a.

CWQCD – 5 CCR 1002-41 RA The Basic Standards for Groundwater (effective November 30, 2009).

CWQCD – 5 CCR 1002-41.4 RA Classification of groundwater.

CWQCD – 5 CCR 1002-41.5 RA Groundwater quality standards.

CWQCD – 5 CCR 1002-41.8 RA Severability. Establishes human health, secondary drinking, agricultural, and water quality standards.

Location Specific

Archaeological and Historic Preservation Act – 16 USC § 469,

AA Evaluation and preservation of historic and archaeological data that may be destroyed by alteration of the terrain resulting from this response action.

Archaeological Resources Protection Act of 1979 – 16 USC §§ 470aa – 47011; 43 CFR 7.4(a) and 7.5(b)(1)

AA This is not an ARAR for the site unless remedial actions uncover or disturb previously unknown archaeological resources. Permit required for any excavation or removal of archaeological resources from public lands or Indian lands. Archaeological resource means any material remains of human life or activities that are at least 100 years of age and which are of archaeological interest.

Permits are not required for on-site actions. If archaeological resources are found, notification will be made, items secured and protected and proper disposition coordinated.

American Indian Religious Freedom Act –a 42 USC § 1996

AA Protect and preserve traditional religions of American Indians, including but not limited to, access to sites, use and possession of sacred objects, and the freedom to worship through ceremonials and traditional rites.





Native American Graves Protection Repatriation Act – 25 USC § 3001; 43 CFR 10.4(b), (c), and (d)

AA Requires notification to Native American organizations and action to secure and protect excavated or inadvertently discovered remains/objects.

Though on-site actions are not required to meet administrative/procedural requirements (e.g.,, notification), notification will be completed as needed to verify compliance with substantive requirements.

If human remains, funerary objects, sacred objects, or objects of cultural patrimony are found, notification will be made, items secured and protected and proper disposition coordinated.

Endangered Species Act – 16 USC § 1536(a)(2) and (c); 16 USC 1538 (a)(1); and 50 CFR 402.01 and 04

AA Prohibits actions that jeopardize the continued existence of any listed species, results in destruction or adverse modification of designated critical habitat of such species (1536), or results in a “taking” of any listed species (1538).

Though on-site actions are not required to meet the administrative/procedural requirements of the Act (e.g., consultation), consultation will be completed as needed to verify compliance with substantive requirements if listed species or critical habitat is identified in the response area.

Migratory Bird Treaty Act – 16 USC § 703 – 712

AA Prohibits the taking, possessing, buying, selling, or bartering of any migratory bird, including feathers or other parts, nest eggs, or products, except as allowed by regulations. This includes disturbing nesting birds.

Bald Eagle Protection Act – 16 USC § 668

AA Prohibits the taking, possessing, selling, purchasing, bartering, offering to sell, purchase or barter, transporting, exporting or importing, at any time or in any manner any bald eagle commonly known as the American eagle or any golden eagle, alive or dead, or any part, nest, or egg thereof of the foregoing eagles.

Antidegradation – 5 CCR 1002-31.08

RA Defines surface water quality based on water quality criteria into three categories: outstanding waters, use-protected, and undesignated.

Action Specific

Clean Water Act – 33 USC §§ 1251, 33 CFR 330

AA The objective of this Act is to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters. North Morgan Gulch runs on the northwest side of the response area. There is the potential for transport off-site from this site





Hazardous Waste – 6 CCR 1007-3, Part 261

AA This part identifies those solid wastes which are subject to regulation as hazardous wastes under parts 262-265, and 268 which are subject to the notification requirements.

Sets Toxicity Characteristic Leaching Procedure (TCLP) concentrations above which generated wastes must be managed as hazardous wastes. Soil, gravel, etc. is generated when it is removed from the ground and taken outside of the area of contamination (AOC).

This requirement is applicable if concentrations in waste exceed TCLP concentrations.

No listed wastes are believed to be present.

Hazardous Waste Management Standards applicable to Generators – 6 CCR-1007-3 Part 262-11 and 6 CCR 1007-3 Part 262 30 – 33

RA A generator needs to characterize all wastes (including media) that are generated and then appropriately manage any hazardous waste. Generator requirements include properly labeling waste containers, storing containers in containment areas and protecting them from the elements.

The site could potentially generate waste that exhibit hazardous characteristics.

Hazardous Waste Management Standards applicable to Use and Management of Containers – 6 CCR 1007-3 Parte 265 171 through 173

RA Containers must be in good condition; compatible with the type of waste placed in the container; always be closed during storage except when it is necessary to add or remove waste; and must not be opened, handled or stored in a manner that could cause it to rupture or leak.

RA if hazardous waste is generated.

Hazardous Waste Management Land Disposal Restriction Requirements 6-CCR 1007-3, 268-7; 268-40; and 268-48

RA Provides testing, tracking, and recordkeeping requirements for generators, treatment, and disposal facilities.

Hazardous waste must be treated to specific concentrations before they can be placed back on the ground.

If a hazardous waste is generated, the hazardous waste characteristic and all UHCs would need to be treated to the applicable land disposal restriction concentration for the characteristic (6-CCR 1007-3, 268-7) or the UHCs (for the UHCs) (6-CCR 1007-3, 268-48) before it can be placed on the ground.

RA if hazardous waste is generated.

Oil Pollution Prevention - 40 CFR 112

AA if >1320

gallons of oil are

managed; RA if <1320

gallons are managed

Governs management of oil or fuels in amounts greater than 1320 gallons, if held in containers 55 gallons or larger.

Requirements include secondary containment, routine inspections of containment before discharging accumulated storm water, implementation of spill prevention procedures, and spill response procedures.

If oil or oil-based compounds are managed during the remediation, then the design and management requirements of this rule would apply.





CERCLA Off-Site Rule – 40 CFR 300.440

AA Any waste from a CERCLA site that is disposed of off-site must be sent to a facility reviewed by EPA under the Off-Site Rule, once a decision document is signed for the waste (e.g., ROD, Action Memo). The concentrations in the waste may be extremely low (below risk-based standards or below TCLP concentrations), but the waste must still go to an Off-Site Rule EPA-approved facility

(http://www.epa.gov/osw/hazard/wastetypes/wasteid/offsite/).

Stormwater – 5 CCR 1002-61, Colorado Discharge Permit System (CDPS) General Permit for Storm water Discharges Associated with Construction Activity, COR030000, dated May 31, 2007

RA Defines use of best management practices for effluent management, erosion and sediment control plan, plans for minimizing discharge and erosion during and after construction, and other general provisions including best management practices, stormwater controls, and monitoring, and other requirements for construction activities that would normally require CDPS permitting by virtue of disturbing more than 1 acre of land.

Obtaining a CDPS permit is an administrative requirement and is not required for on-site activities. However, the requirements and best management practices associated with this general permit are relevant for some of the proposed response actions and should be adhered to.

National Ambient Air Quality Standards – 40 CFR § 50.6 (PM10); 40 CFR § 50.12 (lead)

AA Standards for PM10 emission to air.

AQCC – 5 CCR 1001-3, Regulation No. 1

RA Emission Control for Particulate Matter.

Environmental Covenant,

CRS 25-15-320

AA An environmental covenant is required for any environmental remediation project that does not meet unrestricted use standards and incorporates any engineered feature or structure or requires any monitoring, maintenance, or operation.

NOTES: AA = Applicable AQCC = Air Quality Control Commission CCR = Code of Colorado Regulations CFR = Code of Federal Regulations CRS = Colorado Revised Statutes CWQCD = Colorado Water Quality Control Division PM10 = particulate matter less than 10 micrometers in aerodynamic diameter RA = Relevant and Appropriate USC = United States Code

3.3 Determination of Removal Schedule Potential factors that may affect the removal action schedule include project funding, seasonal weather-related restrictions, and considerations involving successful mobilization of construction equipment to the sites. Based on the removal alternative selected, implementation of the construction activities is anticipated to require one construction season. Annual site inspections for at least the first 3 years after implementation of the removal action will be required to assess the performance of the selected removal



alternative. The NCP requires a minimum public comment period of 30 days for this EE/CA. The USFS will determine the time period between approval of this EE/CA and implementation of the selected removal alternative.





4.0 Identification and Analysis of Removal Action Alternatives

Response actions that may be used to satisfy the removal action objectives generally include waste/debris removal, site grading and waste containment, and surface water management including potential water treatment. These actions are the most qualified actions for the sites, given the site contaminants and the affected media. Per the Guidance on Conducting Non-Time-Critical Removal Actions under CERCLA (EPA, 1993), only the most qualified technologies and applicable presumptive remedies need to be discussed in the EE/CA.

Based on site-specific conditions, various alternatives for the Lancaster Mine sites have been assembled from these general response actions. To ensure that the action will achieve an optimum combination of cost effectiveness and protection of human health and the environment, a range of alternatives were considered. The alternatives evaluated for the Lancaster Mine sites non-time-critical removal action include the following:

Alternative 1—No Action

Alternative 2—Full site restoration with semi-passive treatment of ARD

Alternative 3—Partial site restoration with semi-passive treatment of ARD

Alternative 4—Partial site restoration with control of ARD drainage

Alternative 5—Partial site restoration with no treatment or control of ARD drainage

Table 4-1 identifies the major components of each alternative. A brief description of each alternative is provided in Sections 4.1 through 4.5. Reference is made in these sections to Lower, Middle, and Upper sites; as the mine features visible at the surface are grouped in these three specific areas. In order to reduce repetition and enhance clarity, site restoration elements that are common to all of the alternatives (except for No Action) are presented in Section 4.6.

Figure 2-2 shows the existing general site layout for the Lancaster Mine sites. Pictures 2-1 through 2-6 show existing site conditions of the Upper, Middle and Lower sites. Section 5 contains the results of a detailed evaluation of the alternatives.



TABLE 4-1 Major Components of Alternatives Alternative 1 No Action

Alternative 2—Full site restoration with semi-passive treatment of ARD

All (Lower, Middle and Upper) Sites

Excavate and remove entire volume of waste rock material down to native soil.

Excavate and remove all building and other structural debris.

Regrade excavated areas to match undisturbed ground surface, and cut benching or water bars for erosion control

Add topsoil and/or amendments to the native soil to encourage revegetation over all disturbed areas and to accelerate development of a stable landform

Add temporary drainage controls such as unlined drainageswales, with turf reinforcement mats if necessary, berms for storm water control until vegetation is established as the long-term erosion control solution.

Middle Site

Semi-passive treatment of drainage from adit.

Lower Site

Semi-passive treatment of drainage from seep.

Stream channel restoration following removal of waste rock material.

Alternative 3— Partial site restoration with semi-passive treatment of ARD

All (Lower, Middle and Upper) Sites

Excavate and remove all building and other structural debris.

Add topsoil and/or amendments to the native soil to encourage revegetation over all disturbed areas and to accelerate development of a stable landform.

Lower Site

Construct a rock berm at the base of waste pile LL-200 to stabilize the toe of the slope and to form an area for partial consolidation of the lower Lancaster waste pile. Grade and bench waste rock upslope of the rock berm to match adjacent undisturbed slopes, eliminate over-steepened slopes, and divert storm water around the pile.

Excavate waste rock pile LL-201 from the middle of the drainage, and place this material upslope of the rock berm and as necessary, within the cut of the access road to the site from the Morgan Gulch Road. Grade the waste to match adjacent undisturbed slopes.

Construct a semi-passive treatment system to treat drainage from the seep at toe of LL-200. The system may also include a passive seepage collection system at the toe of the LL-200 slope to reduce water contact with waste, and to collect and route Acid Rock Drainage (ARD) to the treatment system.

Stream channel restoration following regrading of waste rock material.

Middle Site

Reshape the lower waste pile (LL-203) to achieve lower slopes for stable landforms, divert storm water and ARD around the piles, and grade the site to match adjacent undisturbed slopes.

Construct a semi-passive treatment system to treat ARD, similar to that for the Lower Site. This will include collection and routing of ARD to a treatment system.

Upper Site

Construct a rock berm at the base of the upper Lancaster waste pile (TT-206) to stabilize the toe of the slope and provide sediment control. Cut benches or water bars across the face of the waste pile for erosion control, and install drainage swales with turf reinforcement mats and/or riprap around the perimeter of TT-206, to stabilize slope, divert surface water run-on to the pile, and establish vegetative growth as the long-term erosion control solution.



TABLE 4-1 Major Components of Alternatives Alternative 4— Partial site restoration with control of ARD

Similar to Alternative 3 except for no semi-passive treatment of ARD. The focus will be collecting and routing the ARD to the North Morgan Gulch drainage, to reduce the contact between ARD and waste rock.

The seep at the lower site waste pile (LL-200) would be exposed at the toe of the waste rock pile, and a passive seepage collection system would be installed at the toe of LL-200. Drainage material and piping would be installed to re-route the seepage to discharge into North Morgan Gulch drainage.

The discharge from the collapsed adit (LL-102) at the Middle site would be collected near the adit portal and routed down the north side of waste pile LL-202 to discharge into the North Morgan Gulch drainage.

Alternative 5— Partial site restoration with no treatment or control of ARD

Similar to Alternative 3 except for no treatment or collection/routing of ARD. The focus will be to minimize ARD loading through the reduction of surface water recharge to waste from precipitation and snowmelt.

This will primarily be done through by limiting the amount of surface water that may recharge the workings, or that flows onto and through the waste rock piles. The regrading of waste rock piles and storm water controls for reduction of ARD loading is proposed as part of Alternatives 2, 3, 4 and 5.

The selected alternatives are intended to provide a range of reasonable alternatives for evaluation (the purpose of the EE/CA) and not necessarily to select the optimal design. The optimum design based on effectiveness, implementability, and cost, may vary and final design grade, and other details, should be addressed during the removal alternative design process.

4.1 Alternative 1—No Action Alternative 1 would allow existing conditions at the site to continue. No construction activities or institutional controls would reduce the potential of risks to human health and the environment in the area on and adjacent to the mine site. Concentrations of COCs would remain unchanged. The No Action alternative is required by NCP to be used as a comparison against the action alternatives.

4.2 Alternative 2— Full Site Restoration with Semi-Passive Treatment of ARD

Alternative 2 consists of removal of all building and other structural debris, and waste rock, along with impacted sediments and precipitates within the onsite drainage channels at the Upper, Middle, and Lower sites. Prior to removal, the waste rock would be sampled and characterized in order to determine viable disposal options. Disposal options may include consolidation onsite or offsite disposal. Onsite disposal requires a repository, located in an area with favorable hydrologic conditions, where waste would be consolidated and capped. Offsite disposal would require loading the waste rock into trucks and hauling the waste to an offsite repository that accepts mining waste. For costs purposes, it was assumed that an acceptable offsite repository exists within Summit County. The volume of waste rock to be removed is approximately 1,671 cubic yards (cy) from Upper Lancaster, 5,591 cy from



Middle Lancaster, and 7,572 cy from Lower Lancaster, for a total of 14,834 cy. These volume estimates are based on excavation to an assumed bottom (native soil) surface.

Following removal of the debris and waste rock, the disturbed area would be regraded to match adjacent undisturbed slopes, with approximate slopes of 1.1:1, 2.5:1 and 1.4:1 for Upper, Middle, and Lower Lancaster, respectively. Based on the natural slopes, benching or placement of water bars may be required at the Upper and Lower sites to help facilitate erosion control and vegetative growth, resulting in a relatively stable landform. This alternative would essentially result in the sites being restored to approximately the grade that existed before mining activities commenced at the sites.

Surface water will be routed around the reclaimed areas, to the extent possible, to prevent concentrated flow from impacting the newly graded area. Surface water diversions consisting most likely of cut swales lined with turf reinforcement mats and riprap, where feasible, will be constructed around the perimeter of the regraded areas, as feasible, to divert surface water flows around the regraded areas while stable stands of vegetation develop. It is assumed for this and other alternatives that turf reinforcement mats and riprap will provide relatively long-term erosion control. See Section 4.6 for more details.

For this and other alternatives, the disturbed surfaces will remain in a rough condition to reduce erosion, to promote the growth of vegetation when the site is seeded after the removal actions are completed, and to promote future vegetation growth. During construction and until vegetation has been established, silt fencing or other sediment control measures will be used to minimize the amount of sediment that may enter North Morgan Gulch from the Middle and Lower Lancaster sites. Following completion of work, the North Morgan Gulch drainage channel through lower Lancaster will be restored to its current alignment and cross sectional flow area. See Section 4.6 for more details. Access to the mine sites will be limited by scarifying the access roads to Middle and Lower Lancaster and randomly placing boulders at the entrance of the two access roads.

Once the final slope contours are achieved at each site, the top few inches of the remaining native soil will be amended with organic amendment, and/or commercial fertilizer. A layer of topsoil will then be spread over the amended material, in specific areas of low slopes where topsoil is likely to remain in place, to provide a suitable material for seeding. Based on the steep slopes at the site and the limited availability of topsoil, it is assumed that 4-inches of top soil would be placed over 25% of the disturbed areas. The purpose of the amendments is to create a suitable growth medium for establishing vegetation. For cost purposes, it was assumed the topsoil and/or amendments/fertilizer would be imported from the Summit County area and spread on top of the amended waste rock. The site will be seeded with a USFS-approved seed mixture. See Section 4.6 for more details.

For this alternative, ARD discharging from the adit at the Middle site (LL-102) and the seep at the Lower site (LL-04a) would be collected and treated using a semi-passive treatment technology. Prior to installing the treatment system both drainages would be sampled and characterized quarterly for a year for water chemistry and flow rate data to determine if treatment is necessary following the removal of waste rock and to help size the systems to address seasonal variations in flow rate and water quality. For cost estimating purposes, it is assumed that the ARD streams at both the Middle and Lower sites would require treatment and that the nominal, annually-averaged flow rate at each location is 15 GPM.



Limited excavation would be performed at the Middle site to enable effluent to flow freely from what appears to be a collapsed adit, and at the Lower site to enable definition of the seepage source and area. At the Middle site, an appropriately-sized collection sump, such as a lined 6 ft by 6 ft graded precast concrete vault, would be embedded adjacent to the portal to enable ARD to collect and pool adit drainage, for subsequent routing to a treatment unit or discharge. At the Lower site, excavation will enable definition of a seepage face and field-design of a blanket drain to collect and route seepage to a treatment unit or point of discharge. For cost estimating purposes, it is assumed the blanket drain would be constructed of 75 ft of 4 in diameter HDPE slotted piping and routed to a 72 inch precast manhole. From the collection points at the Middle and Lower sites, ARD will be delivered via 4-in diameter HDPE buried pipelines under gravity flow conditions, to treatment units located 200 ft and 60 ft downstream of collection points, respectively.

The preferred ARD treatment technology will be defined following a technology screening based on flow measurements and water quality defined from sampling, but for cost estimating purposes it is assumed that the preferred technology will be a biochemical reactor (BCR); given the currently-understood characteristics of the ARD and climate conditions. A detailed description of BCR geochemistry is provided in Appendix A.

At the Middle and Lower sites, BCRs would likely consist of 2 and 3 pre-cast 6 foot by 6 foot precast concrete vaults with lids, placed in series. The reactive substrate used would be a combination of natural materials (e.g., woodchips, plant residue, grass cuttings, hay, straw manure, and compost) and limestone sand, with 12 inches of limestone gravel at the bottom of each reactor for drainage. For cost estimating purposes, it is assumed that the limestone sand will be mixed at 5% of total volume, however this value should be verified with bench scale testing.

Due to the limited availability of level areas at the Middle and Lower sites and the climate, it is impractical to develop wetland vegetation as a primary or polishing step in treatment. An aeration bed, 15 ft by 15 ft by 3 ft deep filled with an aggregate (sized to achieve a D50 of 6 inches) would be constructed at the BRC discharge point, prior to North Morgan Gulch, to allow for aeration of the treated material and remove excess biological oxygen demand and iron. The treated water will be drained from the center of the aeration bed to North Morgan Gulch, which at the point of discharge will be enhanced with limestone aggregate with a D50

of 6 inches for an area of 5 ft by 50 ft downstream. This will provide for the removal of manganese as a finishing step. Sample ports would be installed upstream and downstream of the treatment units at the Middle and a Lower site to facilitate sampling that confirms influent water chemistry and treatment system effectiveness.

Implementation of this and other alternatives will require a temporary construction staging area for equipment and materials storage and maintenance. It is assumed that the construction staging area will be located adjacent to the east end of the Middle site, in the location of the informal campsite, for work performed at the Upper and Middle sites. For work performed at the Lower Lancaster site, the construction staging area will be located on the south side of the Lower site, between the two waste piles and on dry ground adjacent to the access road. The advantage of both locations is that the areas are generally level and large enough to accommodate trailers and other required facilities, are not readily visible from the main road, are centrally located amongst the three project sites; remain out of the active work zones, and are within the footprint of an area that has already been disturbed.



Annual site inspections for at least three years after completion of construction work would be required to assess the condition of soil cover and success of revegetation. Over this period, sampling of treatment unit effluent discharges at the Middle and Lower sites would be required to confirm treatment system effectiveness. During the first year of operation of the BCR, quarterly samples of both the influent and effluent would be collected to verify system effectiveness and capture seasonal variations in flow and water quality. Following the first year of operation, samples of both the influent and effluent would continue to be collected on a semi annual basis, during times of high and low flow, to verify the system effectiveness and compliance with discharge standards.

Based on an assumed flow rate of 15 GPM, it is expected that reactive materials in the BCR would be replaced every 10 years. However, actual reactive material replacement would take place when effluent concentrations are detected above discharge standards. Operations and maintenance during reactive material replacement would require disposal of spent reactive material at an approved landfill.

4.3 Alternative 3— Partial Site Restoration with Semi-Passive Treatment of ARD

Alternative 3 consists of constructing a rock berm at the base of the large waste pile (LL-200) at the Lower site to stabilize the toe of the waste rock slope, provide additional volume for waste rock consolidation from other sources at the site, and provide erosion control from high stream flows through the site. For cost estimating purposes, it is assumed that the rock berm will be constructed of angular rock having a D50 of 12-in; in-filled with gravel and sand to a height of 6 feet with stable side slopes of 2H:1V, and a top width of 10 ft. The rock berm will tie into natural slopes on either side of the existing waste rock pile, and have an approximate length of 100 ft. Upslope of the rock berm, waste pile LL-200 will be regraded, with benching, to an approximate slope of 1.4:1 or lower to match that of undisturbed slopes adjacent to the pile, reduce undercutting from erosion, and promote vegetative growth. Waste rock downstream of the rock berm, including the smaller Lower pile (LL-201) and sediments from the level areas and stream that are deposited onsite, will be excavated and placed behind the rock berm. If the volume of material excavated from areas downstream of the rock berm exceeds the available storage upslope of the rock berm, the excess waste material will be placed against the cut slope along the access road on the South side of the site. Approximately 3,456 cy of waste material will be excavated and consolidated.

The middle and lower portions of the Middle Lancaster site (LL-203) will be regraded to an approximate slope of 2.5:1 to create stable landforms and to match the natural grade of the undisturbed adjacent lands. The waste rock pile in the upper portion of the site is currently being reclaimed naturally, and therefore no proposed action is proposed for this waste rock pile.

The Upper site (TT-206) will be regarded and benched with an approximate slope of 1.1:1, to match adjacent undisturbed lands, and to enable storm water runoff to be directed to the edges of the pile. As described under Alternative 2, the waste rock will be amended as needed to create a suitable growth medium for establishing vegetation, and the regraded area will be reseeded. Additionally, a small rock berm will be built at the toe of the Upper Lancaster pile to minimize short –term discharge of sediment from the site, while vegetative



cover is being established on the regraded pile. The rock berm will be constructed with angular rock having a D50 of 12-in; in-filled with gravel and sand to a height of 6 feet with stable side slopes of 2:1, and a top width of 10 ft. The rock berm will tie into natural slopes on either side of the existing waste rock pile, and have an approximate length of 50 ft.

Surface water management measures will be implemented as described for Alternative 2. Silt fencing will be placed at the bottom of each waste pile to contain any sediment that may otherwise discharge from the site. Following completion of work, the North Morgan Gulch drainage channel through lower Lancaster will restored to its current alignment and cross sectional flow area. See Section 4.6 for more details.

For this alternative, drainage from the adit at the Middle site and the seep at the Lower site would be collected and treated, as described in Alternative 2. Additionally, a seepage collection system would be installed at the toe of the waste rock slope at the Lower site, in the vicinity of the rock berm. The seepage collection system would be as described under Alternative 2.

As described under Alternative 2, the construction staging area would be located on the south side of the Lower Lancaster site.

Annual site inspections for at least three years after completion of construction work would be required to assess the condition of soil cover and success of revegetation. Over this period, sampling of treatment unit effluent discharge at the Middle and Lower sites would be required to confirm treatment system effectiveness. BCR sampling schedule and BCR reactive material replacement schedule would be carried as described in Alternative 2.

4.4 Alternative 4—Partial Site Restoration with Control of ARD Drainage

Alternative 4 is similar to Alternative 3 in that the waste piles will be regraded and consolidated as described in Alternative 3. However, ARD will not be treated, but rather rerouted to the North Morgan Gulch drainage. For this alternative, contact between ARD and waste rock would be minimized, thus decreasing the toxicity of the ARD. Prior to rerouting, existing discharge points at both the Middle and Lower sites would be daylighted to define and concentrate the point sources; and ARD would be collected via a blanket drain at the Lower site and a vault at the Middle site, and routed as described in Alternative 3. The collected water would be piped through 4 in diameter HDPE buried piping for 200 ft at the Middle Site and 50 ft at the Lower Site to the North Morgan Gulch drainage.

4.5 Alternative 5—Partial Site Restoration with No Treatment or Control of ARD Drainage

Alternative 5 is similar to Alternatives 3 and 4 in that the waste piles will be regraded and consolidated as described in Alternative 3. However, for Alternative 5, ARD will not be treated or controlled via piping. By implementing the regrading described in Alternative 3, ARD loading will be minimized through the reduction of recharge from precipitation and snow melt. Implementing grading and storm water controls and revegetation of the waste



piles is expected to reduce the amount of surface water that flows onto and through the waste rock piles, and recharges groundwater.

4.6 Site Restoration This section discusses site restoration measures that are common to each alternative, except for the No Action alternative. This includes waste regrading and establishing a vegetative cover, removal of all building and structural debris, placement of swales lined with turf reinforcement mats and riprap to control surface water runoff in regraded areas, and stream channel restoration. It should be noted that a detailed analysis of the suitability of available material onsite to support vegetation has not been performed, and the recommendations in the subsections below should be considered preliminary. Further analysis of the site soils and waste rock may be needed to support detailed design of closure measures.

4.6.1 Suitability of Site Topsoil Alternatives 2 through 5 each have a site restoration component that requires revegetation of the sites. However, based on the geology at the sites, there is limited available topsoil. None of the options presented above would generate excess topsoil during regrading activities. Due to steep slopes present at the Upper and Lower sites, the use of topsoil to aid in the revegetation of disturbed areas may be infeasible. It is estimated that top soil placement is only feasible at approximately 25% of disturbed areas, generally being feasible in areas of relatively low slopes. It is expected that amendments will be required for all disturbed areas based on the limited quantity of topsoil. Due to the limited quantity of available topsoil onsite, it is assumed that topsoil will be imported from a local, outside source and delivered by truck to the site.

4.6.2 Suitability of Waste Rock to Support Vegetation The waste rock material does not appear to be highly acid forming, contain a significant amount of salts, or have other undesirable chemical characteristics and may be able to be amended enough so that it will support vegetation. The waste rock material is generally coarse and contains few organics. However, the waste rock piles in some areas do currently support a limited amount of vegetation so there is enough fine-grained material to hold some moisture. The waste rock piles that do not currently support vegetation would likely require the addition of fine-grained soil and/or organics and commercial fertilizer in order to enhance the ability of the waste rock to support significant vegetation.

For the purposes of this EE/CA, it was assumed that topsoil would not be imported in enough quantity to construct a relatively thick (18 to 24 inches) growth medium. Rather, it is assumed that a limited amount of topsoil would be imported to place a 4-inch layer of topsoil over 25% of the disturbed area to facilitate establishing native grasses and other plants. It was also assumed that prior to the placement of the relatively thin topsoil layer, the top 12 inches of waste rock will be amended in order to support the development of deeper rooted plants. Specifically, organic material will be added to the waste rock with the objectives of improving the chemical, biological, and physical properties of the waste rock. This approach is discussed further in the following section.



4.6.3 Amending Waste Rock Several types of organic amendments are often added to waste rock materials to promote the growth of vegetation. These include compost, biosolids, peat, or other materials. It has been demonstrated at high elevation mine sites in Colorado that waste rock can be directly revegetated when properly neutralized, fertilized, and amended with organic matter (Sydnor and Redente, 2002).

Common application rates for organic amendments range considerably based on site characteristics. According the document Mine Reclamation Using Biosolids (EPA, 2001), a common mine reclamation project requires 10 to 25 dry tons of biosolids per acre. The actual application rate at Lancaster will need to be determined based on site-specific parameters and perhaps some limited pilot testing.

An application rate of 20 tons per acre was assumed for cost-estimating purposes. Assuming a 1-foot depth and an average density of 120 pounds per cubic foot for the waste rock, this results in an organic content of almost 1 percent (weight amendment/weight soil) over the top foot of the waste rock material. For cost estimating purposes, it is assumed that organic amendments can be sourced locally.

4.6.4 Removal of Building and Structure Debris All three Lancaster sites contain building debris from the mining operations which will require removal as part of site restoration. Prior to any removal action, all mine waste will be surveyed for hazardous materials such as asbestos, lead and PCBs in transformers. For costing purposes, it is assumed that all building waste onsite in considered to be non hazardous. Approximately, 50 cy of building and structure debris will be removed offsite via a hauling company and disposed of at the Summit County Landfill in Dillon, CO.

4.6.5 Drainage Swales Drainage swales will be constructed to control surface water runoff around disturbed surfaces and waste rock piles. Drainage swales will be placed upgradient and around all regraded and disturbed surfaces to capture and reroute surface water around waste piles. The drainage swales will help control erosion within the footprint of the waste piles and reduce impacts from surface water contacting waste rock. The swales will be constructed in a “V” shape, with 3:1 side slopes to a depth of 2 feet. The swales will be lined with prefabricated turf reinforcement mats, which are imbedded with seed to provide natural erosion control. Turf reinforcement mats will be placed from the top of the swales to the base of the swales, over the full width. The turf reinforcement mats will be anchored in place using staples, stakes and fabric pins.

Riprap will be placed in the bottom 15-20 ft of the drainage swales, where feasible, as they approach the toe of the slope to minimize offsite transport of sediments. Riprap will be placed with a 1-feet depth of aggregate having a d50 of 8-inches placed in the bottom of the swale. The majority of the riprap and rock required to complete the project will have to either be imported from off-site or from a designated borrow source near the project site. Drainage lengths of approximately 400 ft at the Upper site, 425 ft at the Middle site, and 525 ft at the Lower site, with 20 ft of riprap at the toe of the perimeter drainage swales are assumed for purposes of cost estimating.



4.6.6 Stream Channel Restoration Stream channel restoration activities will be performed as necessary following regrading activities at the Lower site. Following the regrading of waste rock material and the removal of waste pile LL-201, the stream channel will be restored with a new channel that is similar to the stream’s current alignment, cross sectional flow area, and sinuosity. The restored stream channel will be lined with rock to the estimated high water line, where appropriate, to help control erosion damage. Stream banks above the rock will be graded to uniform slopes to match undisturbed areas upslope, and revegetated. For the purposes of cost estimating, it is assumed that North Morgan Gulch and the associated drainage channel are 1 ft wide and are a total of 420 ft in length.


5.0 Detailed Analysis of Alternatives

The alternatives analysis uses three main evaluation criteria (effectiveness, implementability, and cost) in accordance with the EE/CA guidance (EPA, 1993). Each evaluation criterion is described in Table 5-1. The detailed analysis of the five alternatives is described in this section and summarized in Table 6-1. Appendix B provides details of the cost estimates for the five alternatives.

TABLE 5-1 Evaluation Criteria

Effectiveness

Protection of human health and the environment

The assessment describes how the action achieves and maintains protection of human health and the environment and achieves site-specific objectives both during and after implementation.

Compliance with ARARs

An alternative is assessed in terms of its compliance with ARARs or, if a waiver is required, how it is justified.

Long-term effectiveness and permanence

An action is assessed in terms of its long-term effectiveness in maintaining protection of human health and the environment after response action objectives have been met. The magnitude of residual risk and adequacy and reliability of post-removal site controls are taken into consideration.

Short-term effectiveness

An action is assessed in terms of its effectiveness in protecting human health and the environment during the construction and implementation of a removal alternative before response action objectives have been met. The duration of time until the response objectives are met is also factored into this criterion.

Implementability

Technical feasibility The ability of the technology to implement the removal alternative is evaluated.

Administrative feasibility

The administrative feasibility factor evaluates requirements for permits, zoning variances, impacts on adjoining property, and the ability to impose institutional controls.

Availability of services and materials

The availability of offsite treatment, storage, and disposal capacity; personnel; services and materials; and other resources necessary to implement the alternative is evaluated.

State and community acceptance

The acceptability of an alternative to the state agency and the community is evaluated.

Cost

Direct and indirect capital costs

Includes costs for construction, equipment and materials, analytical services, engineering and design, and permit/licenses.



5.1 Effectiveness 5.1.1 Overall Protection of Public Health and the Environment Based on the results of the PA/SI, risks to human health and the environment may result from ingestion or direct contact with soils, groundwater and surface water with elevated metal concentrations, in and around the sites. Wind and water erosion of the exposed waste rock pose a risk to human and ecological receptors due to migration of eroding materials.

The five alternatives proposed in this EE/CA offer varying degrees of human health and environmental protection, as discussed in the following text. Four of the alternatives minimize the direct contact exposure risk by discouraging access to the mine sites, providing containment/removal of the waste rock material, reducing potential migration/leaching of metals to ground and surface water, and controlling wind and water erosion to reduce transport of sediments containing high concentration of metals offsite.

Alternative 1 would leave existing conditions at the Lancaster Mine site unchanged. With unrestricted access, the steep and eroding waste rock piles at the Upper and Lower site would remain a potential threat to safety as well as human health and the environment. Sediments would continue to migrate offsite, affecting the surrounding land and surface water. Snowmelt runoff and precipitation would allow surface water to continue to contact and erode the waste rock piles, which act as a source of contamination to North Morgan Gulch drainage. Groundwater from the adit and the seep would continue to be a source of ARD that will migrate offsite.

Alternative 2 consists of removal of waste rock from the site and collecting and treating the ARD prior to offsite discharge into North Morgan Gulch. This alternative offers the highest protection of human health and the environment. After the waste rock is removed the site would be graded, drainage swales constructed, and the site revegetated to minimize erosion and promote reclamation of the site. By capturing and treating ARD, further impacts to North Morgan Gulch and the local groundwater would be greatly reduced.

Alternative 3 reduces erosion of the waste rock piles that may impact surface and groundwater and treats the ARD prior to discharge. Alternative 3 also offers a high degree of protection but, unlike Alternative 2, the waste rock piles will remain in place except for the Lower Site where the lower pile will be consolidated. Erosion of the waste rock piles would be greatly reduced but not completely eliminated as it would be for Alternative 2. The Upper and Lower waste rock piles will be graded and stabilized with rock berms. The sites will be graded and vegetated to promote reclamation. By capturing and treating ARD, further impacts to North Morgan Gulch drainage and the local groundwater would be greatly reduced.

Alternative 4 is similar to Alternative 3 with impacts from the waste rock piles significantly reduced, but for this alternative the ARD will not be treated prior to discharge. Alternative 4 offers a high degree of protection to onsite receptors, but only moderate protection of offsite receptors. ARD will continue to be discharged to North Morgan Gulch drainage and will continue to migrate offsite, at a reduced rate, impacting both surface and groundwater. The ARD will be collected and conveyed to North Morgan Gulch drainage which should



reduce contaminant loading to surface and groundwater due to reduced leaching of metals from the waste rock.

Alternative 5 is the least protective of alternatives 2-5 because it provides for no treatment or control of the ARD. The waste rock piles will be addressed in a similar fashion as Alternatives 3 and 4, with a similar effectiveness and reduction of risks. For this alternative however, ARD will continue to flow through the waste rock piles and flow to groundwater and North Morgan Gulch drainage. Although the ARD will not be collected or treated directly, it is possible the generation of ARD may be somewhat reduced through the grading of the waste rock piles and control of surface water.

5.1.2 Compliance with ARARs and Other Criteria, Advisories, and Guidance Table 3-1 contains an analysis and discussion of potential ARARs for the Lancaster Mines non-time-critical removal action. Table 5-2 identifies the primary ARARs for each alternative. Alternative 1 would not involve any construction or O&M activities and therefore would not trigger any ARARs that control such activities.





TABLE 5-2 Primary ARARs Invoked by Alternatives Implementation

ARAR

Alternative

1 2 3 4 5

National Primary and Secondary Drinking Water Regulations

Possible routes of contamination from mine site to groundwater, used as a drinking supply, still

exist.

Removal of waste rock and treatment of ARD eliminates potential

drinking water contact with contaminated media.

Regrading of waste rock reduces contact of

potential drinking water with contaminated media

and treatment of ARD eliminates contaminant discharge to potential

drinking water sources.


potential drinking water with contaminated media and containment of ARD

reduces contact with contaminated media, prior to discharge to potential drinking water sources.


potential drinking water with contaminated media, however contamination to drinking water from ARD

still exists.

National Surface Water Regulations

Possible routes of contamination from mine site to surface water still

exist


surface water contact with contaminated media.

Regrading of waste rock reduces contact of surface water with contaminated media and treatment of

ARD eliminates contaminant discharge to

surface water.

Regrading of waste rock reduces contact of surface water with contaminated

media and containment of ARD reduces contact with contaminated media, prior

to discharge to surface water


media, however contamination to surface

water from ARD still exists.

State Surface Water Standards

Possible routes of contamination from mine site to surface water still

exist


surface water contact with contaminated media.



surface water.



to discharge to surface water


media, however contamination to surface

water from ARD still exists.

State Groundwater Quality

Possible routes of contamination from mine site to groundwater still

exist


groundwater contact with contaminated media.



groundwater.



to discharge to groundwater.


media, however contamination of

groundwater from ARD still exists.



TABLE 5-2 Primary ARARs Invoked by Alternatives Implementation

ARAR

Alternative

1 2 3 4 5

National Hazardous Waste Regulations

NA-No waste being transported offsite

Applicable to waste being transported to landfill




National Air Quality Standards

NA Applicable to construction

activities Applicable to construction



activities

State Stormwater Management NA

Applicable to construction activities and ARD

treatment


treatment


collection

Applicable to construction activities

State Environmental Covenant

NA Required for ARD treatment system

Required for waste rock remaining on site, rock

berm and ARD treatment system

Required for waste rock remaining on site, rock

berm and ARD collection system

Required for waste rock remaining on site and rock

berm

Historic and Archaeological

NA NA, no excavation of

native soils NA, no excavation of


native soils NA

Native American Cultural Resources

NA NA, restoring site NA, partially restoring site NA, partially restoring site NA

Migratory Birds and Protected/ Endangered Species

NA NA, no excavation of



native soils NA

NOTES: NA=not applicable


Alternative 2 includes the excavation and offsite disposal of the waste rock, along with capture and treatment of ARD. Removal of the waste rock to an onsite or offsite repository will eliminate the migration of contaminated soils to North Morgan Gulch drainage. Additionally, regrading, drainage swales and revegetation will help reduce erosion of newly placed soils by routing storm water runoff around the disturbed area. Capture and treatment of ARD will eliminate the transportation of contaminated groundwater to both surface water bodies and groundwater, by treating contamination prior to discharge back to the aquifer. Periodic maintenance of the ARD treatment system will be required to ensure that the system remains effective over time.

Alternative 3 controls migration of contaminated soils by controlling surface water drainage and limiting the effects of wind erosion from unprotected soils through site grading, drainage swales, and revegetation. By routing storm water runoff around waste rock and covering the exposed waste rock with vegetation, transportation of contaminated soils to surface water is reduced. Additionally, the installation of a rock berm at the Upper and Lower sites will help limit the potential for soils being transported offsite. The rock berm at the lower site will also provide a barrier between surface water in North Morgan Gulch and the waste rock pile during periods of stream flow. Periodic inspections are required to assess the effectiveness of the regraded and vegetated waste piles. Capture and treatment of ARD will eliminate the transportation of contaminated groundwater to both surface water bodies and groundwater, by treating contamination prior to discharge back to the aquifer. Periodic maintenance of the ARD treatment system will be required to ensure that the system remains effective.

Alternative 4 is similar to Alternative 3 in the proposed control methods of controlling surface water and preventing wind and water erosion over the mine site. Controlling ARD will reduce erosion through regraded and vegetated areas, along with limiting contact time of ARD with waste rock. ARD control will reduce transport of contaminated groundwater to both surface water and groundwater, however it will not eliminate the risk. Periodic inspections of the ARD collection system should be performed to evaluate if the system is operating as designed.

Alternative 5 is similar to Alternative 3 in the proposed control methods of controlling surface water and preventing wind and water erosion over the mine site. Alternative 5 does not provide for any control or treatment of ARD, thus erosion of waste rock piles and transport of contaminants to surface water and groundwater will continue.

Alternatives 2 through 5 all trigger construction-related ARARs, including surface water quality and national air quality standards. Presuming that the activities would be carried out in compliance with the applicable requirements, Alternatives 2 through 5 would comply with ARARs for construction. Alternative 2 offers the highest compliance with ARARs because of the removal or treatment of all sources of contaminants. Alternatives 3, 4 and 5 offer similar physical control for contaminants in waste rock. However, Alternatives 2 and 3 offer the greatest physical control and treatment of ARD, while Alternative 4 offers greater physical control of ARD as compared with Alternative 5.

5.1.3 Long-Term Effectiveness and Permanence Alternative 1 would leave existing conditions at the Lancaster Mine site unchanged. This alternative would be least effective of the five alternatives in the long term.



Alternative 2 offers the greatest amount of long-term effectiveness and performance by removing waste rock, treating ARD and restoring the mine sites to their natural settings. Removing the waste rock dumps would eliminate the migration of sediments offsite and to surface water. The slopes would be similar to the natural surroundings, resulting in less erosion and therefore less migration of sediment, which can affect the surrounding land, surface water, and downstream water users. Capturing and treating ARD would reduce infiltration of ARD to groundwater and surface water, and eliminate erosion channels from ARD runoff. Additionally, revegetation and storm water diversion would allow for natural reclamation over time.

Alternative 3 offers a high degree of long-term effectiveness, although less than Alternative 2 because waste rock will remain onsite. Grading and revegetation of the waste rock piles would allow for long term slope stability, reduce surface water erosion, and support natural reclamation. Surface water controls around the disturbed areas would reduce erosion and therefore result in less migration of sediment, which can affect the surrounding land, surface water, and downstream water users. Capturing and treating ARD would reduce infiltration of ARD to groundwater and surface water. Alternative 3 offers a high degree of long term protection; however, there is a potential for nominal erosion of the waste rock piles although this would be at a greatly reduced rate and would decrease over time.

Alternative 4 offers similar long-term effectiveness as Alternative 3 with respect to the waste rock piles. However, it provides less long-term effectiveness with respect to ARD. The ARD would be collected and conveyed to the drainage, reducing infiltration to groundwater and surface water. However, because ARD is not treated, long-term effectiveness for the protection of surface water in North Morgan Gulch would not be provided. Alternative 4 offers a high degree of long term protection; however, there is a potential for nominal erosion of the waste rock piles although this would be at a greatly reduced rate and would decrease over time.

Alternative 5 offers the least amount of long-term effectiveness to human and ecological health. Like Alternatives 3 and 4, implementation of Alternative 5 allows for long-term control of offsite migration of contaminated soils. However, it does not address human and ecological risks associated with ARD onsite or the discharge of ARD to surface water. Alternative 5 offers a high degree of long term protection; however, there is a potential for nominal erosion of the waste rock piles although this would be at a greatly reduced rate and would decrease over time.

5.1.4 Short-Term Effectiveness Alternative 1 would have the least short-term effectiveness because there would be no construction. Human and ecological receptors will continue to be at risk due to contaminated soils, groundwater and surface water.

Alternatives 2 through 5 would initially carry some short-term safety risk because of the transport and operation of construction equipment. Also, the amount of time required to construct Alternatives 2 through 5 would be directly related to onsite worker exposure risks. Implementation of Alternative 2 requires the greatest amount of onsite worker hours. Implementation of Alternatives 3 and 4 requires similar amount of onsite worker hours; therefore, they share similar short-term effectiveness. Alternative 5 requires the fewest onsite worker hours to implement.



Potential exposure risk from contact with waste rock, groundwater, surface water and dust is also a concern in the short term with these alternatives. Safety risks can be mitigated by proper planning, implementation of safety procedures, monitoring particulate emissions and vigilance by onsite coordinators while workers are onsite. Precautions to inform the local residents of the construction and to keep the general public away from the site would also be implemented to help reduce the risk to the community. Any transport of impacted material would be contained and covered prior to removal offsite. Short-term environmental impacts by implementation of these alternatives would be addressed by the following:

Improve access road(s) and install stormwater management BMPs

Install signage and site access controls during construction to limit access to the site by the public

Upon completing construction, seed the disturbed area around the mine site for erosion control

5.2 Implementability 5.2.1 Technical Feasibility Alternative 1 would not involve construction, so there are no technical constraints to its implementation.

Alternatives 2, 3, 4 and 5 would require contractor services to construct these alternatives. Level D personal protection equipment (PPE) is assumed to be sufficient for onsite workers. Details on PPE would be addressed in the site Health and Safety Plan. Dust generated during soil moving could impact the environment, but State and United States Occupational Safety and Health Administration (OSHA) regulations governing dust suppression would be implemented. The time required to complete these alternatives would be one construction season, assumed to be about 4 months over the summer. Seed specifications including seed mix and seeding methods will need to be established.

Alternative 2 requires the offsite transport of the greatest amount of material, an estimated 14,584 cy this alternative would require heavy equipment access to all three mine sites, which are currently only accessible by a 4WD road. Additionally, there is no access road to Upper Lancaster, making access with heavy construction equipment infeasible. Steep slopes at the Upper and Lower Lancaster sites may present accessibility issues during excavation. Lastly, construction traffic hauling waste would significantly increase the amount of vehicle activity in Montezuma, and coordination with residents would be necessary.

Alternative 3, 4 and 5 require the regrading and consolidation of the waste rock piles. This alternative could be implemented at the Upper Lancaster site using hand tools or small construction equipment. Truck traffic hauling rock for the berm would increase vehicle activity in Montezuma, however it would be significantly less than Alternative 2. Alternative 3 would require additional impacted area and construction times than 4 and 5, due to the installation of the infrastructure for the ARD biochemical reactor. No material from the waste rock dumps would be removed offsite.



5.2.2 Administrative Feasibility Alternative 1 has no administrative constraints to its implementation.

Alternatives 2, 3 and 4 require excavation of the waste rock dumps but do not pose any significant administrative challenges. Due to the control and treatment of ARD, a National Pollution Discharge Elimination System (NPDES) permit for surface water discharge to North Morgan Gulch may be required for Alternatives 2 and 3.

Alternative 5 involves minimal construction activities. Administrative constraints would be limited to trucking permits.

All alternatives except for Alternative 1 may require other state or county required permits, such as a Colorado Stormwater Discharge Permit for construction activities.

5.2.3 Availability of Services and Materials Alternative 1 has no constraints associated with the availability of services and materials.

Most of the services and materials associated with the implementation of Alternatives 2 through 5 would be available locally or regionally. All services and materials including access road improvements, vegetation clearing, and erosion control seeding would be readily available.

5.2.4 State and Community Acceptance State and community acceptance will be evaluated through the community involvement process following standard methods used by the USFS including public meeting and providing information to stakeholders. As members and representatives of the state and community provide comments, removal action alternatives will be reassessed and potentially modified. State and community concerns will be carried into final consideration of an alternative recommended by the EE/CA process and into the final selection of an Alternative in the Action Memorandum.

5.3 Cost Table 5-3 summarizes the direct and indirect capital costs for the five alternatives. Direct capital costs pertain to construction, materials, land, transportation, and analysis of samples. Indirect capital costs pertain to design, legal fees, and permits. Appendix B contains information and assumptions used to estimate costs.



TABLE 5-3 Order of Magnitude Cost Estimates for Alternatives

Alternative Capital Costs1

Maintenance Costs2 (3 yrs)

Lancaster Mine

Alternative 1—No Action $ 0 $ 0

Alternative 2—Full Restoration, ARD Treatment $678,238 $17,500

Alternative 3—Partial Restoration, ARD Treatment $240,411 $20,000

Alternative 4—Partial Restoration, ARD Control $216,007 $10,000

Alternative 5—Partial Restoration $177,288 $10,000

NOTES: 1 The capital cost estimate is consistent with a Class 4 cost estimate per the Association for the Advancement of Cost Engineering, with an accuracy range of -30%/+50%.

2 For Alternative 2, assumed $2,500 per year for 3 years for site visits and limited site work the first year in regards to the waste rock piles. For Alternatives 3, 4, and 5, assumed $5,000 for first year for site visit and moderate site work and $2,500 for the next 2 years for site visit and limited site work for the waste rock piles. Additionally, for Alternatives 2 and 3 costs associated with evaluating the ARD treatment is assumed to be $10,000 for the first year.

Unit prices used for the cost estimate were based on construction references such as RSMeans Heavy Construction Cost Data (2013), or from construction costs at similar sites. Actual unit prices for the work at the Lancaster Mine Site may vary depending on availability of equipment, resources and time of the year. The objective of the cost estimate is to develop an estimate that complies with EE/CA guidance, and is of sufficient accuracy to provide the basis for comparison of removal alternatives.





6.0 Comparative Analysis

The five non-time-critical removal action alternatives were compared against each other to evaluate the relative performance of each alternative in relation to each of the criteria (Table 6-1). A rating scale ranging from poor to excellent was used for each criterion. The criteria used in this comparison are the same as in Section 5, namely effectiveness, implementability, and cost.





TABLE 6-1 Comparative Analysis of Alternatives

Option Eff

ecti

ven

ess

(Sed

imen

tati

on

)

Eff

ecti

ven

ess

(Dir

ect

Exp

osu

re)

Eff

ecti

ven

ess

(AR

D E

xpo

sure

)

Im

ple

men

tab

ility

Rel

ativ

e C

ost

Ove

rall

Rat

ing

Comments

Alternative 1 No Further Action ● ● ● ● ● ● Least cost, but threats to human health and the environment remain.

No discernable improvement in downstream habitat.

Alternative 2 Full Site Restoration with Semi-Passive Treatment of ARD

● ● ● ◑ ● ○ Protective of human health and the environment and meets all the site removal action objectives.

Difficult to implement especially at the Upper site, where access is limited

Will result in returning the site to the most natural state, as all waste rock will be removed and the final grade will most closely match native slopes.

Full treatment of ARD prior to discharge to North Morgan Gulch

Due to removal of all waste rock material, this alternative has the highest cost.

Improvement of downstream habitat due to increase in water quality and elimination of offsite migration of sediments.

Long term O&M costs associated with operation of BCR.

Alternative 3 Partial Site Restoration with Semi-Passive Treatment of ARD

◑ ◑ ● ○ ◑ ◑ Protective of human health and the environment, although waste rock does remain onsite and may have erosion greater than Alternative 2

Moderately simple to implement and can be done using hand tools at the Upper site. Slopes will closely match native slopes.

Full treatment of ARD prior to discharge to North Morgan Gulch

Due to treatment of ARD, this Alternative has moderately high costs.

Improvement of downstream habitat due to increase in water quality and decrease of offsite migration of sediments.

Long term O&M costs associated with operation of BCR.



TABLE 6-1 Comparative Analysis of Alternatives

Option Eff

ecti

ven

ess

(Sed

imen

tati

on

)

Eff

ecti

ven

ess

(Dir

ect

Exp

osu

re)

Eff

ecti

ven

ess

(AR

D E

xpo

sure

)

Im

ple

men

tab

ility

Rel

ativ

e C

ost

Ove

rall

Rat

ing

Comments

Alternative 4 Partial Site Restoration with Control of ARD

◑ ◑ ○ ◑ ◑ ◑ Moderately protective of human health and the environment due to no treatment of the ARD and waste rock does remain onsite


Containment of ARD prior to discharge to North Morgan Gulch does not treat contaminants in groundwater or those discharged to surface water

Due to containment of ARD, this Alternative has moderately high costs.

Improvement of downstream habitat due to decrease of offsite migration of sediments. Water quality would remain the same,

Alternative 5 Partial Site Restoration with no Treatment or Control of ARD

○ ○ ● ◑ ◑ ◑ Low protection of human health and the environment due to no treatment of containment of the ARD and waste rock does remain onsite


No treatment or containment of ARD will continue to provide direct pathway for exposure, may erode regarded waste rock, and will continue discharge of contaminants into surface and ground water

This Alternative has relatively low costs.

No discernable improvement in downstream habitat.

● Excellent

◑ Good ○ Average or No Impact

◑ Fair

● Poor


7.0 References

Cappa, Jim/Chief of Minerals, Colorado Geological Survey. 2010. http://www.geosurvey.state.co.us/Default.aspx?tabid=237. Accessed September 23, 2013.

CH2M HILL. 2013. Work Plan for Lancaster Mines Engineering Evaluation and Cost Analysis. CH2M HILL. August.

Colorado Department of Public Health and the Environment, Water Quality Control Commission. 2008. Snake River Total Maximum Daily Limits Assessment Snake River and Peru Creek, Summit County, Colorado. August.

Colorado Department of Public Health and the Environment, Water Quality Control Commission. 2010a. Colorado Primary Drinking Water Regulations, 5 CCR 1003-1. Effective 11/30/2010.

Colorado Department of Public Health and the Environment, Water Quality Control Commission. 2010b. The Basic Standards and Methodologies for Surface Water, 5 CCR 1002-31. Effective 11/30/2010.

Colorado Department of Public Health and the Environment, Water Quality Control Commission. 2011. The Basic Standards for Ground Water, 5 CCR 1002-41. Effective 01/01/2011.

Colorado Mountain College. 2011. Preliminary Assessment & Site Inspection Report for Lancaster & Tip Top Mines: Montezuma Mining District, Summit County, CO.

Colorado Parks and Wildlife (CPW). 2011. Threatened and Endangered List. Last Updated: December 21, 2011. http://wildlife.state.co.us/WildlifeSpecies/SpeciesOfConcern/ThreatenedEndangeredList/Pages/ListOfThreatenedAndEndangeredSpecies.aspxAccessed: September 17, 2013

Fitzgerald, J. P., C. A. Meaney and D. M. Armstrong. 1994. Mammals of Colorado. Denver Museum of Natural History and University Press of Colorado, Niwot.

Ford, Karl L., Ph.D./United States Department of the Interior, Bureau of Land Management. 2004. Risk Management Criteria for Metals at BLM Mining Sites. October.

Lovering, T.S., 1935, Geology and Ore Deposits of the Montezuma Quadrangle, Colorado. United States Geological Survey Professional Paper 178. United States, Washington

Miles, R. and Fletcher, R., 1980. Soil Survey of Summit County, Colorado. United States Department of Agriculture, Soil Conservation Service.

Sydnor, M.E., and E.F. Redente. 2002. “Reclamation of High-elevation, Acidic Mine Waste with Organic Amendments and Topsoil.” J Environ Qual. September–October. Department of Rangeland Ecosystem Science, Colorado State University.



United States Environmental Protection Agency (EPA). 1993. Guidance on Conducting Non-Time-Critical Removal Actions Under CERCLA. Office of Emergency and Remedial Response. September 17.

United States Environmental Protection Agency (EPA). 2001. Mine Reclamation Using Biosolids. Office of Solid Waste and Emergency Response. August.

United States Environmental Protection Agency (EPA). 2009. National Primary and Secondary Drinking Water Regulations. May.

United States Fish and Wildlife Service (USFWS). 2013. IPaC- Information, Planning, and Conservation System. http://ecos.fws.gov/ipac/wizard/chooseLocation!prepare.action Accessed: September 17, 2013.

United States Fish and Wildlife Service (USFWS). 2013. Critical Habitat Portal. http://criticalhabitat.fws.gov/crithab/ Accessed: September 17, 2013.

United States Geographical Survey (USGS). 2004. http://tapestry.usgs.gov/Default.html. Accessed September 10. 2013

Western Regional Climate Center (WRCC). 2013. http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?co2281. Accessed September 10, 2013

White River National Forest (WRNF). 2010. http://www.wildernet.com/pages/area.cfm?areaID=0215&CU_ID=1. Accessed September 10, 2013.

Figures

Date post:	08-Nov-2020
Category:	Documents
Upload:	others
View:	0 times
Download:	0 times

Engineering Evaluation/ Cost Analysis, Lancaster...

Documents