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COMPLETION REPORT

YAK TUNNEL

MONITORING WELLS

CALIFORNIA GULCH SITE

LEADVILLE, COLORADO

February 1992

Prepared for

Res-ASARCO, Incorporated

Leadville, Colorado

Woodward-Clyde

Woodward-Clyde Consultants

4582 South Ulster Street Parkway

Stanford Place 3, Suite 1000

Denver, Colorado 80237

Project No. 22907C-22327 T2210
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B ••••••• COMPLETION REPORT

* YAK TUNNEL

I MONITORING WELLS

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 CALIFORNIA GULCH SITE

I LEADVILLE, COLORADO

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February 1992

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Res-ASARCO, Incorporated

Leadville, Colorado

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Woodward-Clyde Consultants

4582 South Ulster Street Parkway

Stanford Place 3, Suite 1000

Denver, Colorado 80237

Project No. 22907C-22327 T2210
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Section

1.0 INTRODUCTION

1.1 PURPOSE AND SCOPE

1.2 SITE BACKGROUND

1.3 REPORT ORGANIZATION

2.0 SITE DESCRIPTION

2.1 GEOLOGY

2.2 HYDROGEOLOGY

2.3 SELECTION OF WELL LOCATIONS

2.4 SURFACE GEOPHYSICS

2.4.1 Electromagnetic Surveys

2.4.2 Very Low Frequency (VLF) Surveys

2.4.3 Resistivity Soundings

2.4.4 High Resolution Seismic Reflection

2.5 HISTORICAL RESOURCES SURVEY

3.0 INSTALLATION OF BBW-1

3.1 DRILLING SUMMARY

3.2 GEOLOGIC CONDITIONS

3.3 SELECTION OF SCREENED INTERVAL

3.4 WELL COMPLETION

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TABLE OF CONTENTS

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TABLE OF CONTENTS (Continued)

Section

4.0 INSTALLATION OF BBW-2

4.1 DRILLING SUMMARY

4.2 GEOLOGIC CONDITIONS

4.3 SELECTION OF SCREENED INTERVAL

4.4 WELL COMPLETION

5.0 INSTALLATION OF BBW-3

5.1 DRILLING SUMMARY

5.2 GEOLOGIC CONDITIONS

5.3 SELECTION OF SCREENED INTERVAL

5.4 WELL COMPLETION

6.0 INSTALLATION OF BBW-4

6.1 DRILLING SUMMARY

6.2 GEOLOGIC CONDITIONS

6.3 SELECTION OF SCREENED INTERVAL

6.4 WELL COMPLETION

7.0 INSTALLATION OF BBW-5

<3 7.1 DRILLING SUMMARY

7.2 GEOLOGIC CONDITIONS

7.3 SELECTION OF SCREENED INTERVAL

7.4 WELL COMPLETION

7.5 ADDITIONAL GEOPHYSICAL LOGGING

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TABLE OF CONTENTS (Continued)

Section

8.0 INSTALLATION OF BBW-7

8.1 DRILLING SUMMARY

8.2 GEOLOGIC CONDITIONS

8.3 SELECTION OF SCREENED INTERVAL BBW-7

8.4 WELL COMPLETION

9.0 WELL DEVELOPMENT

9.1 DEVELOPMENT PROCEDURES

9.2 DEVELOPMENT OF BBW-1

9.3 DEVELOPMENT OF BBW-2

9.4 DEVELOPMENT OF BBW-3

9.5 DEVELOPMENT OF BBW-4

9.6 DEVELOPMENT OF BBW-5

9.7 DEVELOPMENT OF BBW-7

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10.0 SUMMARY OF CHANGES FROM THE WORK PLAN/SAP 10-1

10. 1 CHANGES IN THE WORK PLAN

10.2 CHANGES IN THE SAMPLING AND ANALYSIS

11.0 DISCUSSION OF HYDROGEOLOGIC CONDITIONS

11.1 GENERAL HYDROGEOLOGIC CONDITIONS

1 1.2 WELL BBW-1 HYDROGEOLOGY

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PLAN 10-1

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11.4 WELL BBW-3 HYDROGEOLOGY 11-3

11.5 WELL BBW-4 HYDROGEOLOGY 11-4

11.6 WELL BBW-5 HYDROGEOLOGY 11-4

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TABLE OF CONTENTS (Concluded)

Section

1 1.7 WELL BBW-7 HYDROGEOLOGY

12.0 REFERENCES

LIST OF FIGURES

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FIGURE 2-1 PROPOSED PIEZOMETER/MONITORING WELL

LOCATIONS

FIGURE 3-1 GEOLOGIC AND WELL COMPLETION

FIGURE 4-1 GEOLOGIC AND WELL COMPLETION

FIGURE 5-1 GEOLOGIC AND WELL COMPLETION

FIGURE 6-1 GEOLOGIC AND WELL COMPLETION

FIGURE 7-1 GEOLOGIC AND WELL COMPLETION

FIGURE 8-1 GEOLOGIC AND WELL COMPLETION

LIST OF APPENDIXES

APPENDIX A FIELD BORING LOGS

LOGS, BBW-1

LOGS, BBW-2

LOGS, BBW-3

LOGS, BBW-4

LOGS, BBW-5

LOGS, BBW-7

APPENDIX B DOWNHOLE GEOPHYSICAL LOGS (see Volume H)

APPENDIX C WELL COMPLETION LOGS

^ APPENDDC D WELL DEVELOPMENT LOGS

APPENDIX E SURVEYING DATA

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1.0

INTRODUCTION

This section describes the purpose of this document, and the general site history and

location..

1.1 PURPOSE AND SCOPE

The purpose of this report is to summarize the drilling, well completion and

development of six piezometers/monitoring wells installed for the Yak Tunnel Operable

Unit, California Gulch Site, Leadville, Colorado. This report also presents the data

collected in the field during the installation and development of the wells.

The six monitoring wells discussed in this document are part of the monitoring program

for the selected remedy determined by the Record of Decision (ROD) March 29, 1988,

as modified on March 23, 1989, for the Yak Tunnel Operable Unit (EPA 1988 and

1989a). The Modified ROD (EPA 1989a, p. 1-2) describes the eight components of the

selected remedy, one of which is a monitoring program to establish baseline

preremediation water quality and to predict and evaluate hydrologic changes.

The objectives of the monitoring program (EPA 1988, pp. 40-41) are as follows:

• "Define the preremediation groundwater and surface water conditions

against which the impacts of the selected remedy can be evaluated;

• Provide information on the effectiveness of the remedy by monitoring

water quality and water levels in the vicinity of the plugs; and

• Provide ongoing information on how the remedy is affecting regional

groundwater and surface water."

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The baseline monitoring program will consist of the establishment and routine

monitoring of groundwater and surface water locations for at least one year prior to

tunnel plugging until equilibrium conditions are reached as a result of the remediation.

The Res-ASARCO Joint Venture proposed changes to the remedy components in the

Selected Remedy Component Change Proposal (SRCCP) (Res-ASARCO 1990a). One

change was to reduce the groundwater monitoring portion of the monitoring program

from 23 monitoring well locations to seven locations. This change has been incorporated

in the Draft Explanation of Significant Differences (ESD) document issued by EPA

(EPA 1991). Six of the seven wells were installed in the Fall of 1992. The seventh well

will be installed later.

The locations of the monitoring wells were outlined in the Technical Memorandum for

Piezometers and Monitoring Wells (Res-ASARCO 1991). The construction methods are

presented in the Work Plan, Yak Tunnel Operable Unit, (Res-ASARCO 1990b) and the

Sampling and Analysis Plan (SAP), Yak Tunnel Operable Unit (Res-ASARCO 1990c).

1.2 SITE BACKGROUND

The California Gulch site is in Lake County, Colorado, approximately 100 miles

southwest of Denver. The Phase I Remedial Investigation (RI) study area, which

includes the City of Leadville (population 3,800), encompasses an 16 square mile

watershed that drains along California Gulch to the Arkansas River west of Leadville.

The California Gulch drainage basin ranges from 10,000 to 14,000 feet above mean sea

level (msl) in elevation.

Mining began in the Leadville area in 1859 with the discovery of gold in California

Gulch. Initial mining of placer deposits was short-lived but led to the discovery of

silver-bearing lead carbonate. The search for ore expanded and resulted in the discovery

and extensive mining of replacement deposits of lead and silver. This was followed by

mining of gold and associated copper, and later by mining of zinc and manganese.

As the mines were deepened and mining areas expanded, effective drainage of the mine

workings became an economic necessity. The Yak Tunnel and the Leadville Drainage

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Tunnel were constructed as the two major drainage facilities beginning in 1895 and 1943,

respectively.

Mining in the area has continued at varying levels of intensity since its beginning in the

mid-1800's; it has continued through depressions, labor unrest and two world wars.

Today there remains only limited active mining. The Yak Tunnel and the Leadville

Drainage Tunnel, however, continue to function as designed and drain the connected

mine workings.

1.3 REPORT ORGANIZATION

Section 2.0 of this document describes the site location, geology and pre-drilling

activities. Sections 3.0 through 8.0 describe the drilling and installation of six monitoring

wells. Section 9.0 discusses development of the wells, while Section 10.0 summarizes

deviations or changes from the Work Plan and SAP. Section 11.0 discusses the

hydrogeologic conditions encountered. Section 12.0 contains references.

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2.0

SITE DESCRIPTION

This section describes the geology and hydrogeology of the Yak Tunnel area. In

addition, an explanation of the selection of well locations is included.

2.1 GEOLOGY

Bedrock in the Yak Tunnel area consists of a granitic and metamorphic Precambrian

basement overlain by Paleozoic sedimentary beds of dolomite, limestone, sandstone,

siltstone, and shale. The total thickness of sedimentary rocks exposed in the area ranges

from 0 to 1600 feet (Emmons et al. 1927). Younger igneous intrusive rocks (porphyry)

from large deep-rooted irregularly-shaped masses (stocks) and sheets between

sedimentary beds (sills). Alteration by ore-forming fluids has changed the porphyry,

particularly the sills, to predominantly mica minerals.

Unconsolidated sedimentary deposits in the area were formed by alluvial (surface water)

or glacial processes. Alluvial deposits of stratified silt, sand and gravel occur in present

stream valleys, including California Gulch. Glacial deposits of poorly sorted gravel- to

silt-sized sediment cover the bedrock in the northeast part of the Yak Tunnel area to

a thickness of 0 to 220 feet.

The sedimentary and igneous bedrock is intensely broken by numerous major and minor

faults. Major faults have predominantly reverse (compressional) or normal (extensional)

displacement. On a district-wide scale, northerly-striking major faults cause an irregular

stair-step arrangement of fault-bounded blocks with downward displacement of the

blocks toward the west. Major faults occurring in the vicinity of the Yak Tunnel include

the Iron, Tucson Maid, Adelaide, Mike, Pilot, Weston, Colorado Prince, and Ball

Mountain Faults.

The major faults typically include adjacent zones of displacement and deformation. The

interior zone of displacement contains soft gouge developed on subparallel planes of

movement, separated by crushed rock (fault breccia). The gouge is a mixture of finely

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pulverized rock and clay. The zone of displacement may be several tens of feet wide,

and thickness of gouge on the slip planes ranges from several inches to several feet. The

zone of displacement is enveloped by the zone of deformation, which grades from

fractured rock to fault breccia toward the central zone of displacement. The zone of

deformation ranges from a few feet to several hundred feet in width (Emmons et al.

1927).

Minor faults and fissures occur within the structural blocks bounded by the major faults.

Minor fault types include reverse, normal, and flat (bedding plane) faults. The minor

faults have a wide range of orientations, although a predominant orientation exists in

some areas, such as the N30°E to N50°E trend of minor faults in the Resurrection mine

area (Jonson 1955). Rocks adjacent to intersections of minor faults are generally highly

shattered (Emmons et al. 1927).

2.2 HYDROGEOLOGY

Groundwater in the Yak Tunnel area occurs in bedrock and alluvial aquifers. The

bedrock aquifer drains toward stream valleys and into alluvial aquifers. The alluvial

aquifer consists of sand to boulder size unconsolidated sediments. The bedrock aquifer

has three types of porosity that contribute to groundwater storage and flow: primary

(intergranular rock porosity); secondary (faults, fractures, and karst); and mine workings.

The primary porosity and permeability of most of the rock types in the area are low, and

are relatively insignificant compared to secondary porosity and permeability, and to the

influence of mine workings.

Groundwater flow in bedrock is influenced by the major and minor faults. Major faults

separate the strata into a stair-step arrangement of fault blocks with decreasing

elevations towards the west. The displacement of bedrock blocks along the major faults

has created large-scale complexities in the regional bedrock aquifer due to separation

and displacement of permeable aquifer units. Relatively impermeable gouge zones along

the major faults appear to restrict groundwater flow between blocks, perpendicular to

fault planes (Emmons et al. 1927). Large flows of water were commonly encountered

when gouge-bearing fault zones were breached by early mining activities (Emmons et al.

1927), suggesting that the faults acted as barriers between faulted aquifer blocks. The

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rock adjacent to the faults however, is generally permeable and readily conducts water

along the plane of the fault zone through the fracture zones adjacent to the faults.

Groundwater movement within the fault blocks is facilitated by permeable highlyfractured zones adjacent to the major faults and by numerous interconnecting minor

faults within the blocks.

The effects of mining and mine drainage have dramatically changed the hydrogeologic

system. Groundwater flow in the vicinity has been redirected toward the Yak Tunnel,

which was constructed originally for the purpose of large scale groundwater interception

and drainage from the adjacent mineralized zones in order to facilitate mining. Mine

workings that are distant from the Yak Tunnel but connected to it, also appear to

capture water from neighboring drainages, such as Evans Gulch. Natural permeability

within the fault blocks is increased in some areas by free-flowing mine workings, arid

new fractures caused by mine subsidence. The Yak Tunnel and the associated network

of mine workings perforate fault gouge zones, thereby enhancing hydraulic

interconnection between groundwater bearing fault-blocks.

2.3 SELECTION OF WELL LOCATIONS

The locations of the bedrock monitoring wells (Figure 2-1) were selected using the

following criteria:

• The screened intervals of the monitoring wells should be installed in

hydraulically conductive fault zones (or fracture zones adjacent to such

zones) within the bedrock aquifer.

• Monitoring wells should be located away from mine workings that are

interconnected to the Yak Tunnel system to avoid measuring water levels

that simply reflect subsurface conduit flow through mine workings.

• Monitoring wells should be located far enough from the tunnel to reflect

large scale hydrologic conditions but not so far as to be on the other side

of a groundwater divide.

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• One monitoring well should be placed near the portal to evaluate the

possibility of flow away from the tunnel in that area.

Monitoring well drill site locations and estimated screened interval depths were

identified based on interpretation of geologic field relationships in conjunction with

available geologic maps and literature. Surface geophysical methods were used to

confirm the location of the drill sites and indicate potential hydraulically conductive

zones near the anticipated screened intervals. The summarized selection criteria for

each well is described below. A more detailed explanation of well site selection criteria

is presented in the Technical Memorandum for Piezometers and Monitoring Wells (ResASARCO 1991). The well locations are shown on Figure 2-1.

Well BBW-1

Well BBW-1 is located 1,100 feet north of the Yak Tunnel and 420 feet west of the

surface trace of the Pilot Fault on the western slope of Breece Hill. The BBW-1 drill

site was located using the surface trace of the fault from the Behre (1953) map and an

approximate 65 °W dip of the fault reported in the Emmons et al. (1927) report and

Thompson (1974) cross-sections. The mapped surface features were field checked, and

the geologic interpretation was confirmed with surface geophysical methods.

Well BBW-2

Well BBW-2 is located 900 feet south of the Yak Tunnel and 235 feet west of the

approximate surface trace of the Pilot Fault near the bottom of Whites Gulch. The

position of the BBW-2 drill site was located using the Behre (1953) map and an

approximate 65 °W dip indicated in cross-sections by Emmons et al. (1927), and

Thompson (1974). The mapped surface features were field checked, and the geologic

interpretation was confirmed with surface geophysical methods.

Well BBW-3

Well BBW-3 is located 2,500 feet northwest of the Yak Tunnel and 175 feet west of the

approximate surface trace of the Weston Fault. The BBW-3 drill site was located using

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the surface trace from Behre's (1953) geologic map and a 78 °W dip taken from crosssections by Emmons et al. (1927) and Thompson (1974). The mapped surface features

were field checked, and the geologic interpretation was confirmed with surface

geophysical methods.

Well BBW-4

Well BBW-4 is located 1,750 feet southeast of the Yak Tunnel and 225 feet west of the

approximate trace of the Weston Fault. The position of the BBW-4 drill site was located

using the approximately 78 °W dip of the Weston Fault. This dip is based on work

within the Yak Tunnel indicated in cross-sections by Emmons et al. (1927) and

Thompson (1974) in conjunction with the surface trace of the west branch of the Weston

Fault, recently mapped by ASARCO personnel using intercepts in drill holes and mine

workings. The mapped surface features were field checked, and the geologic

interpretation was confirmed with surface geophysical methods.

Well BBW-5

Well BBW-5 is located near the northeast end of the Yak Tunnel, approximately

2,500 feet southwest of the Diamond Shaft and 1,500 feet northwest of the Yak Tunnel.

This drill site is located west of the Resurrection mine workings near the bottom of

Evans Gulch.

Well BBW-5 is intended to monitor water levels in the vicinity of the upgradient

(northeast) terminus of the Yak Tunnel. The drill site 5 area, unlike the other proposed

drill site areas, is not crossed by a major fault zone. Based on the available data, only

moderate- and minor-sized faults were identified in the drill site 5 area. The borehole

at drill site 5 was located to intercept inferred northeast-striking minor faults associated

with the Silent Friend Fault. The geologic interpretation was confirmed with surface

geophysical methods.

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Proposed Well BBW-6

The proposed site of Well BBW-6 is located along the Ball Mountain Fault

approximately 3,500 feet northwest of the top of Ball Mountain (Res-ASARCO 1990a).

This location is currently within an area of piezometric surface depression caused by

pumping from the Black Cloud Mine. It has been indicated that water levels in the area

of the proposed BBW-6 location are probably 2,500 feet below the ground surface, which

places it well below the elevation of the Yak Tunnel (Mr. Chuck Klimper, pers. comm.

1990). Therefore, the specific location and installation of this piezometer will be

deferred until such time as pumping ceases in the Black Cloud Mine.

Well BBW-7

Well BBW-7 is located approximately 350 feet south of the Yak Tunnel portal and

500 feet northeast of California Gulch. The BBW-7 drill site was located using the

subsurface geometry and thickness of the Iron Fault zone reported by Emmons et al.

(1927) and the surface trace of the fault mapped by Behre (1953). The mapped surface

features were field checked, and the geologic interpretation was confirmed with surface

geophysical methods.

2.4 SURFACE GEOPHYSICS

Surface geophysical methods were used in connection with optimizing final placement

of each Yak Tunnel monitoring well. The decision to utilize geophysics was made after

initial monitoring well sites were selected, and available subsurface information

reviewed. Because of the technical challenge of drilling each monitoring well into

subsurface fault zones to depths of 400-1200 feet, and considering the uncertainty of

subsurface fault orientations at each site, a prudent recommendation for additional

subsurface characterization was made. Surface geophysical surveys were designed to

obtain additional subsurface information and aid estimation of the degree of faulting and

the orientation and dip of fracture zones at each monitoring well site. At a minimum,

the geophysical results were intended to allow better extrapolations of the fault zones

to depth, in comparison to those made solely with the previously available site

information.

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Several surface geophysical methods were used to obtain near-surface information as

well as deeper information on fault zone orientation. The methods included

electromagnetics (EM), very low frequency (VLF), electrical resistivity soundings, and

high-resolution seismic reflection (HRSR).

2.4.1 Electromagnetic Surveys

EM surveys were conducted at all proposed monitoring well sites to obtain near-surface

(upper 100-feet) information on faulting. EM methods provide a rapid means of

measuring the electrical conductivity of subsurface soil and rock. The EM method

involves the induction of an electrical current into the earth. A time-varying magnetic

field is generated by a transmitter coil that induces a current into the ground. A

secondary field is generated by the primary field due to subsurface conductivity

variations, and is measured by a receiver coil. Changes in magnitude and phase of the

individual currents are output as voltages and directly related to the subsurface electrical

conductivity.

Conductivity is a function of the soil or rock composition, the porosity and permeability

of the subsurface units, and the conductivity of the fluids filling the pore spaces. As a

result, EM can be a useful tool for assessing lateral variations in soil or rock, faulting

relationships, and the relative degree of fluid saturation. Individual conductivity values

are not necessarily diagnostic in themselves, but the variations in conductivity, both

laterally and vertically, are significant. EM techniques respond to subsurface electrical

conductors, and thus thin resistive zones within conductive materials may have little or

no effect on the EM response. However, in areas of high resistivity such as the Leadville

area, seemingly minor variations in the conductivity can become significant.

2.42 Very Low Frequency (VLF) Surveys

VLF was conducted at all monitoring well sites to correlate with the EM data, and to

aid near-surface control of faulting. VLF methods measure various components of the

electromagnetic field generated by existing military radio transmitters used for longdistance communication. A primary electromagnetic field is generated by the transmitter

horizontally with a frequency of 15 kHz to 30 kHz. This field consists of a vertical field

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component and a horizontal field component, although the horizontal field dominates

in a uniform or homogeneous earth. A secondary field is created over areas in which

the primary field propagates along a boundary separating two different resistivities. This

secondary field will cause fluctuations in the local horizontal and vertical field strengths,

which are measured by the VLF instrument. Collection of VLF raw data involves the

measurement of the real and imaginary components of the complex ratio between the

vertical and horizontal electromagnetic fields. Data are often displayed as a percentage

of the horizontal and vertical field strength ratio. Because of the characteristics it

measures, VLF can be an effective tool for locating water-bearing fracture zones in

crystalline rock.

VLF was conducted at all monitoring well sites to correlate with the EM data, and to

aid near-surface control of faulting.

2.4.3 Resistivity Soundings

Resistivity surroundings were applied at monitoring well site 1, using electrical, or direct

current (DC) resistivity soundings, which allow the measurement of subsurface soil or

rock resistivities. A DC resistivity sounding, using the Schlumberger electrode array,

provides sufficient information to estimate a resistivity versus depth profile. DC

resistivity using the Schlumberger array involves inducing electrical current into the

ground using a pair of surface electrodes. The resulting potential field (voltage) is

measured at the ground surface between a second pair of electrodes. Subsurface

resistivities are calculated from the separation and geometry of the electrode positions,

the applied current, and the measured voltage.

In general, soil and rock act as electrical insulators and are, therefore, highly resistive.

The flow of current is conducted primarily through moisture-filled pore spaces. Thus

resistivity (the inverse of conductivity) is a function of the same parameters as that of

conductivity, and water-bearing fracture zones are seen as resistivity lows.

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2.4.4 High Resolution Seismic Reflection

HRSR surveys were conducted at monitoring well sites 2, 3, 4, 5 and 7 to obtain deeper

information on fault zone orientations. HRSR has, in recent years, been applied to

shallow (less than 1500 feet) subsurface investigations for environmental and engineering

applications. Shallow applications of the method involves scaling down of all data

acquisition parameters in comparison to those commonly used in traditional oil and gas

exploration. This scaling down of all parameters however, potentially complicates

problems not generally significant with deeper targets. These problems include nearsurface seismic noise and ground-roll, sensitivity to surface statics (elevation and nearsurface velocity variations), and sensitivity to recording filters. As a result, the success

of a HRSR survey is often site dependent. HRSR can, under favorable subsurface

conditions (i.e., existing seismic velocity contrasts between shear zones and unfaulted

units), produce a diagnostic picture of the subsurface orientation of the fault zone.

The seismic reflection method consists of generating an acoustic wave source near the

ground surface and recording acoustic waves that are reflected from subsurface layers

and fault zones, or any interface in which a measurable seismic velocity contrast exists.

Reflected acoustic waves are detected by geophones and recorded on a seismograph.

HRSR surveys commonly use the Common Depth Point (CDP) technique of data

collection which allows resolution of seismic reflection events that have low signal-tonoise (S/N) ratios. Utilizing the CDP method, reflection points in the subsurface are

recorded from multiple offsets at different source and receiver pairs. This multiplicity

of data (commonly denoted "fold") allows us to stack reflection energy together,

increasing the S/N ratio.

2.5 HISTORICAL RESOURCES SURVEY

Numerous historic sites and artifact locations are scattered throughout the Leadville

District. Since the disturbance of historic sites by drilling activities is not permitted,

historic resources surveys were performed at all of the proposed drill site areas.

Foothills Engineering Consultants, Inc. personnel, archeological consultants to

Res-ASARCO, identified the historic resource survey areas shown in Figure 2-1 as being

devoid of historic resources. Historical resources were identified along the access to

22907A-22327/R2.2 02-28-92/RPT 2-9
* Woodward-Clyde

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• Drill Site 7. Res-ASARCO received permission from the Colorado State Historical

Preservation Office to cross the identified area.

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LEGEN D

Mj PIEZOMETER/MONITORING WELL LOCATION

/ APPROXIMATE LIMIT OF MINE WORKINGS

S CONNECTED TO YAK TUNNEL

MAP FROM BEHRE, 1953

0 1000 20OO

5=^=E=

SCALE IN FEET

4000

Job No. 22327-7103

D.B.

1/9/91

PROPOSED PIEZOMETER/MONITORING

WELL LOCATIONS

2.1
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3.0

INSTALLATION OF BBW-1

3.1 DRILLING SUMMARY

The drilling of monitoring well BBW-1 was conducted according to Standard Operating

Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well Installation in

Bedrock. A site-specific summary of the BBW-01 drilling follows. Figure 3-1 shows

geologic and well completion logs.

Borehole drilling for Monitoring Well BBW-1 started on September 9, 1991 and core

drilling at the bottom of the hole was finished on September 12, 1991. Surface casing

was installed to 20 feet below ground surface using the air rotary drilling method and

a 20.5-inch diameter tricone bit. The main bore from the bottom of the surface casing

to 903 feet was drilled by the rotary dual-wall air reverse-circulation method with a

downhole hammer and an 8.5-inch diameter bit. The lower part of the hole, between

903 feet and the total depth of 914 feet, was drilled with a 6-inch outside diameter (OD)

diamond coring bit with a 15-foot-long core barrel, using air and water as the drilling

fluid.

Air rotary drilling for the surface casing was accomplished without difficulty. The

drilling of the main part of the borehole with the reverse-circulation downhole hammer

proceeded normally, except that the downhole hammer iced up and ceased working

several times. The hammer was pulled up 20 feet or less from the bottom of the hole

and was allowed to thaw before proceeding with drilling. Core drilling was successful

and all of the 11-foot core run was recovered.

32 GEOLOGIC CONDITIONS

A summary of the geologic conditions encountered in the BBW-1 borehole follows.

Detailed geologic information is contained in Appendix A - Field Boring Logs.

22907A-22327/R2.3 02-05-92/RPT 3-1
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The BBW-1 borehole is located adjacent to the Pilot Fault within or near the Breece

Hill stock. The first 10 feet of the hole were drilled in a colluvium of weathered rock

of the Gray Porphyry group. The remainder of the hole, to a total depth of 914 feet

below ground surface, was drilled in the Gray Porphyry of the Breece Hill stock. The

porphyry is moderately to intensely altered to sericite throughout the length of the

borehole. Some minor argillic alteration occurs locally in conjunction with the sericitic

alteration. Disseminated pyrite is ubiquitous, forming 1% to 5% of the rock volume, and

as much as 15% pyrite occurs locally. Fracture coatings of pyrite and veinlets of pyrite

and quartz were also observed locally.

Several faults were indicated during drilling by an increased content of clay and fines in

the drill cuttings. Only three such apparently faulted intervals were encountered from

10 to 880 feet below ground surface. Limonite (oxidation) does not occur in the

apparent fractures below 430 feet. One fracture occurring at 895 feet had a 3-inch open

space that the drill string penetrated without hammering. Drill core from the 903 to 914

foot interval exhibits numerous small fractures.

3.3 SELECTION OF SCREENED INTERVAL

Water production was recorded during drilling by measuring the amount of water

produced by air lifting. Beginning at 725 feet below the surface, water production was

measured every 20 feet. In addition, specific conductivity was measured in the produced

water. Approximately three gallons per minute of water was produced until a depth of

905 feet when the flow increased to approximately 4.5 gallons per minute. The specific

conductivity also increased in the sample at 905 feet.

The following downhole geophysical logs were run in BBW-1:

Temperature - fluid resistivity

16"-64" normal resistivity, SP and IP

Caliper

Full wave-form sonic

Gamma and neutron

22907A-22327/R2.3 02-05-92/RPT 3-2
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Borehole deviation

Acoustic televiewer

The results of drilling, water measurements and downhole geophysics suggested the

presence of significant fracture zones at approximately 855 feet and 905 feet. The

acoustic televiewer, caliper and temperature\fluid resistivity logs showed the fracture

zones most clearly. Based on these data, the screened interval was selected to be 860

to 900 feet. The filter pack zone was extended below the screen to capture water from

the fracture zone at 905 feet. The filter pack was also extended 10 feet above the

screened interval to capture flow from the fracture zone at 855 feet.

3.4 WELL COMPLETION

The installation of monitoring well BBW-1 was conducted according to Standard

Operating Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well

Installation in Bedrock. A site-specific summary of the BBW-1 well installation follows.

More detailed well installation data are presented in Appendix D - Well Completion

Logs.

Subsurface installation of monitoring well BBW-1 commenced on September 12, 1991.

The tremie pipe and well construction materials were decontaminated prior to well

installation according to SOP No. 1 - Decontamination. The tremie pipe was lowered

down the open hole to a depth of 900 feet. Forty feet of 2-inch ID, 0.05-inch slot, wire

wound, channel packed stainless steel screen was used for this well. The well screen was

capped on the bottom, attached to the well casing, and set at a depth of 900 to 860 feet

below ground surface. The lower part of the well casing consists of 520 feet of flushthreaded 2-inch ID Schedule 10 stainless steel casing. The upper 340 feet of well casing

consists of flush-threaded 2-inch ID Schedule 80 low-carbon steel pipe. Centralizers

were placed at the top and the bottom of the well screen, and at approximately 100-foot

intervals along the length of the well casing. Neither the tremie pipe nor the well

screen/casing encountered any obstructions as they were lowered down the open hole.

The 8 X 12 mesh Colorado Silica Sand filter pack was installed from 914 to 848 feet

below ground surface by pumping the sand down the tremie pipe with potable water.

22907A-22327fll2.3 02-05-92/WT 3-3
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The tremie pipe was raised incrementally as the filter pack level was raised. The

bentonite seal was emplaced between 848 and 721 feet by pumping a mixture of 3/8-inch

bentonite chips and potable water down the tremie pipe and incrementally raising the

tremie as the bentonite seal level was raised.

The grout composition used in the borehole annulus consists of approximately 35 100-lb

bags of Type V Portland cement, one 50-lb bag of bentonite powder, and one 80-lb bag

of calcium chloride pellets mixed with potable water to produce approximately 400

gallons of grout. The first lift of grout was pumped down the tremie pipe and allowed

to harden over the four day shift break. The remaining grout was pumped down the

tremie pipe in 400 gallon batches. The tremie pipe was raised after the pumping of each

batch of grout. After the grout hardened, the annulus was topped off with additional

grout and a protective surface casing with locking cap was installed. The subsurface well

construction activities were completed on September 17, 1991. The mortar collar,

mortar blanket, and steel guard posts were installed at a later date.

The well casing and screen has been subsequently tested for straightness and possible

damage by passing a bailer through the entire length. No problems were encountered

in the bailer test. The location and elevation of the well have been surveyed (see

Appendix E).

22907A-22327/M.3 02-28-92/RPT 3-4
GEOLOGIC LOG WELL COMPLETION

ALTERATION AND

MINERALIZATION

FAULTS AND

FRACTURES

LITHOLOGY — i

QUATERNARY

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\N*^^ GROUT

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--^ STAINLESS STEEL CASING

., — BENTONITE CHIP SEAL

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^STAINLESS STEEL 50 SLOT

CHANNEL PACK SCREEN

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Job No. : 22327

Prepared by : D.X.B.

Date : 11/14/91

GEOLOGIC AND WELL

r* ^\ L j r*t i ^TI ^ k i i f\ o c*

COMPLETION LOGS

BBW-1

YAK TUNNEL OPERABLE UNIT ^^

FIG. 3-1
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4.0

INSTALLATION OF BBW-2

4.1 DRILLING SUMMARY

The drilling of monitoring well BBW-2 was conducted according to Standard Operating

Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well Installation in

Bedrock. A site-specific summary of the BBW-2 drilling follows.

Borehole drilling for Monitoring Well BBW-2 started on October 16, 1991 and was

finished on October 17, 1991. Surface casing was installed to 20 feet below ground

surface using the air rotary drilling method and a 20.5-inch diameter tricone bit. The

main bore from the bottom of the surface casing to 442 feet below ground surface was

drilled by the rotary dual-wall air reverse-circulation method with a downhole hammer

and an 8.5-inch diameter bit. From a depth of 442 feet to 451 feet, the hole was drilled

with 6-inch OD diamond coring bit with a 15-foot long core barrel, using air and water

as the drilling fluid. After the core barrel was removed, the reverse-circulation downhole

hammer was installed again and the hole was drilled to total depth of 475 feet.

Air rotary drilling for the surface casing was accomplished without difficulty. The

reverse-circulation downhole hammer drilling proceeded normally. The core drilling rate

was very slow, and downward progress ceased after 8.5 feet of drilling. The rock

material extracted from the core barrel was broken into angular fragments with long

dimensions of several inches. Approximately 50% to 75% of the 8.5-foot core run was

recovered.

4.2 GEOLOGIC CONDITIONS

A summary of the geologic conditions encountered in the BBW-2 borehole follows.

Detailed geologic information is contained in Appendix A - Field Boring Logs.

The BBW-2 borehole is located adjacent to the Pilot Fault within or near the Breece

Hill stock. The first 15 feet of the hole were drilled in a colluvium of weathered rock

22907A-22327/R2.4 02-05-92/RPT 4-1
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of the Gray Porphyry group. The remainder of the hole, to a total depth of 475 feet,

was drilled in the Gray Porphyry. The porphyry is moderately to intensely altered to

sericite throughout the length of the hole. Some minor argillic alteration occurs locally

in conjunction with the sericitic alteration. Disseminated pyrite is ubiquitous, forming

1 to 5 percent of the rock volume, with greater amounts to about 15% occurring locally.

Fracture coating of pyrite and veinlets as pyrite and quartz were also observed locally.

Several faulted areas were indicated during drilling by an increased content of clay and

fines in the drill cuttings. Three such faults occur in the interval from 130 to 170 feet

below ground surface, and four faults appear to occur between 350 and 405 feet. The

area between 430 and 445 feet appears to be strongly fractured, as indicated by large

angular fragments in the drill cuttings. Limonite (oxidation) does not appear to occur

below 385 feet in the borehole. The cored interval from 442 to 451 feet has small, open

fractures of variable orientation occurring every few inches along the surface of the core.

Slickensides are common in the core.

4.3 SELECTION OF SCREENED INTERVAL

Water production was recorded during drilling by measuring the amount of water

produced by air lifting. Beginning at 345 feet below the surface, water production was

measured every 20 feet. In addition, specific conductivity and pH were measured in the

produced water. Approximately five gallons per minute of water was produced at 345

feet. Flow increased gradually to eight gallons per minute at 425 feet. At 445 feet the

flow increased to approximately 23 gallons per minute. The specific conductivity

decreased from 270 uS/cm (equivalent to umhos/cm) in the sample at 425 feet to 253

uS/cm in the sample from 445 feet.

The following downhole geophysical logs were run in BBW-2:

Temperature - fluid resistivity

16"-64" normal resistivity, SP and IP

Caliper

Full wave-form sonic

22907A-22327/R2.4 02-24-92/RPT 4-2
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Borehole deviation

Acoustic televiewer

The results of drilling, water measurements and downhole geophysics suggested the

presence of numerous fractures from approximately 350 to 450 feet. The acoustic

televiewer and caliper logs showed a zone of fractures from 420 to 450 feet. Based on

these data, the screened interval was selected to be 420 to 460 feet. The filter pack was

extended 10 feet above the screened interval to provide protection of the screened

interval from the bentonite seal.

4.4 WELL COMPLETION

The installation of monitoring well BBW-2 was conducted according to Standard

Operating Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well

Installation in Bedrock. A site-specific summary of the BBW-2 well installation follows.

More detailed well installation data is presented in Appendix D - Well Completion Logs.

Subsurface installation of monitoring well BBW-2 commenced on October 18,1991. The

tremie pipe and well construction materials were decontaminated prior to well

installation according to SOP No. 1 - Decontamination, and were installed in an open

hole. Forty feet of 2-inch ID, 0.05-inch slot, wire wound stainless steel screen was used

for this well. The well screen was capped on the bottom, attached to the well casing,

and set at a depth of 460 to 420 feet below ground surface. The well casing consists of

420 feet of flush-threaded 2-inch ID Schedule 10 stainless steel casing. Centralizers were

placed a.t the top and the bottom of the well screen, and at approximately 100-foot

intervals along the length of the well casing. Neither the tremie pipe nor the well

screen/casing encountered any obstructions as they were lowered down the open hole.

The 8 X 12 mesh Colorado Silica Sand filter pack was installed from 475 to 408 feet

below ground surface by pumping the sand down the tremie pipe with potable water.

The tremie pipe was raised incrementally as the filter pack level was raised. The

bentonite seal was emplaced between 408 and 314 feet by pumping a mixture of 3/8-inch

bentonite chips and potable water down the tremie pipe and incrementally raising the

tremie as the bentonite seal level was raised.

22907A-22327/R2.4 02-24-92/WT 4-3
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The grout composition used in the borehole annulus consists of approximately 35 100-lb

bags of Type V Portland cement, one 50-lb bag of bentonite powder, and one 80-lb bag

of calcium chloride pellets mixed with potable water to produce approximately

400 gallons of grout. The first lift of grout was pumped down the tremie pipe and

allowed to harden for 24 hours. The remaining grout was pumped down the tremie pipe

in 400 gallon batches. The tremie pipe was raised after the pumping of each batch of

grout. After the grout hardened, the annulus was topped off with additional grout and

a protective surface casing with locking cap was installed. The subsurface well

construction activities were completed on October 19, 1991. The mortar collar, mortar

blanket, and steel guard posts were installed at a later date.

The well casing and screen has been subsequently tested for straightness and possible

damage by passing a bailer through the entire length. No problems were encountered

in the bailer test. The location and elevation of the well have been surveyed (see

Appendix E).

22907A-22327/R2.4 02-28-92/RPT 4-4
Woodward-Clyde Consultants -

GEOLOGIC LOG WELL COMPLETION

QUATERNARY

COLLUVIUM

PORTLAND CEMENT

GROUT

16" ID SURFACE CASING

PORTLAND CEMENT

GROUT

2" ID SCHEDLUE 10

STAINLESS STEEL CASING

BENTONITE CHIP SEAL

FILTER PACK

STAINLESS STEEL 50 SLOT

CHANNEL PACK SCREEN

NATURAL COLLAPSE RUBBLE

SCALE: 1"=100'

Job No. :

Prepared by :

Date :

22327

D.X.B.

11/14/91

GEOLOGIC AND WELL

COMPLETION LOGS

BBW-2

YAK TUNNEL OPERABLE UNIT ^

FIG. 4-1
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5.0

INSTALLATION OF BBW-3

5.1 DRILLING SUMMARY

The drilling of monitoring well BBW-3 was conducted according to Standard Operating

Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well Installation in

Bedrock. A site-specific summary of the BBW-3 drilling follows.

Borehole drilling for Monitoring Well BBW-3 started on October 2, 1991 and core

drilling at the bottom of the hole was finished on October 4, 1991. Surface casing was

installed to 48 feet below ground surface using the air rotary drilling method and a 20.5-

inch diameter tricone bit. The main bore from the bottom of the surface casing to 785

feet below ground surface was drilled by the rotary dual-wall air reverse-circulation

method with a downhole hammer and an 8.5-inch diameter bit. The lower part of the

hole, between 785 feet and the total depth of 800 feet, was drilled with a 6-inch OD

diamond coring bit with a 15-foot-long core barrel, using air and water as the drilling

fluid.

Air rotary drilling for the surface casing was accomplished without difficulty. Drilling

the main part of the borehole with the reverse circulation downhole hammer proceeded

normally, except that the downhole hammer iced up and ceased working several times.

The hammer was tripped out of the hole the first time it iced up. Subsequent icing was

remedied by injecting 30 to 50 gallons of 15% to 20% calcium chloride solution into the

drill string. Core drilling was successful and all of the 15 foot core run was recovered.

5.2 GEOLOGIC CONDITIONS

A summary of the geologic conditions encountered in the BBW-3 borehole follows.

Detailed geologic information is contained in Appendix A - Field Boring Logs.

The BBW-3 borehole is located adjacent to the Weston Fault in an area north of the

Breece Hill stock. The top 60 feet of the hole were drilled through Quaternary glacial

22907A-22327/R2.5 02-OS-92/RPT 5-1
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till. The remainder of the hole was drilled through Paleozoic strata and Tertiary

porphyry sills. Both the Gray Porphyry group and the Pando Porphyry are common in

the borehole. The Gray and Pando porphyries compose 30% and 38% of the drilled

interval respectively. Both of the porphyry units are have moderate to strong sericitic

alteration, and the Gray Porphyry locally contains minor disseminated pyrite. Paleozoic

units represented in the borehole include the Belden Formation, the Manitou Formation,

the Peerless Formation, and the Sawatch Quartzite. The Paleozoic section is incomplete

in the borehole, possibly due to displacement by the porphyry sills.

Minor fractures appear to occur locally throughout the drilled interval. These fractures

can be inferred from the increased content of clay and fines in the drill cuttings,

commonly in association with an elevated concentration of limonite. Limonite is

common above a depth of 785 feet. Unusually large angular fragments in the drill

cuttings may also indicate fractures. The most significant fault appears to occur at 755

feet, at the contact between the Sawatch Quartzite and the Gray Porphyry. The cored

interval from 785 to 800 feet has only three small partially open fractures.

5.3 SELECTION OF SCREENED INTERVAL

Water production was recorded during drilling by measuring the amount of water

produced by air lifting. Beginning at 705 feet below the surface, water production was

measured every 20 feet. In addition, specific conductivity and pH were measured in the

produced water. Approximately two gallons per minute of water was produced at 705

feet. The flow increased to approximately 9 gallons per minute at 745 feet and 12

gallons per minute at 765 feet. The specific conductivity decreased as the water

production increased.

The following downhole geophysical logs were run in BBW-3:

Temperature - fluid resistivity

16"-64" normal resistivity, SP and IP

Caliper

Full wave-form sonic

22907A-22327/R2.5 02-05-92/RPT 5-2
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Borehole deviation

Acoustic televiewer

The results of drilling, water measurements and downhole geophysics suggested the

presence of numerous fractures from approximately 720 to 750 feet. The acoustic

televiewer and caliper logs showed a zone of fractures from 720 to 750 feet. The

temperature/fluid resistivity log showed an increase of water at approximately 730 feet.

Based on these data, the screened interval was selected to be 740 to 780 feet. The filter

pack was extended 25 feet above the screened interval (to 715 feet) to provide

protection of the screened interval from the bentonite seal and to capture flow from the

fracture zone from 720 to the top of the screen.

5.4 WELL COMPLETION

The installation of monitoring well BBW-3 was conducted according to Standard

Operating Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well

Installation in Bedrock. A site-specific summary of the BBW-3 well installation follows.

More detailed well installation data is presented in Appendix D - Well Completion Logs.

Subsurface installation of monitoring well BBW-3 commenced on October 5, 1991. The

tremie pipe and well construction materials were decontaminated prior to well

installation according to SOP No. 1 - Decontamination. The tremie pipe was lowered

down the open hole to a depth of 785 feet. Forty feet of 2-inch ID, 0.02-inch slot, wire

wound stainless steel screen was used for this well. The well screen was capped on the

bottom, attached to the well casing, and set at a depth of 780 to 740 feet. The lower

part of the well casing consists of 340 feet of flush-threaded 2-inch ID Schedule 10

stainless steel casing. The upper 400 feet of well casing consists of flush-threaded 2-inch

ID Schedule 80 low-carbon steel pipe. Centralizers were placed at the top and the

bottom of the well screen, and at approximately 100-foot intervals along the length of

the well casing. Neither the tremie pipe nor the well screen/casing encountered any

obstructions as they were lowered down the open hole.

The lower part of the hole, from 800 feet to approximately 785 feet below ground

surface, was filled with natural material that sloughed off the wall of the borehole. One

22907A-22327/R2.5 02-05-92/RPT 5-3
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bag of 3/8-inch bentonite chips was pumped down the tremie with potable water to

backfill and seal the hole below the screened interval. The top of the bentonite/rubble

backfill was tagged with the tremie pipe at a depth of 786 feet below ground surface.

The 8 X 12 mesh Colorado Silica Sand filter pack was installed from 786 to 715 feet

below ground surface by pumping the sand down the tremie pipe with potable water.

The tremie pipe was raised incrementally as the filter pack level was raised. The

bentonite seal was emplaced between 715 and 615 feet by pumping a mixture of 3/8-inch

bentonite chips and potable water down the tremie pipe and incrementally raising the

tremie as the bentonite seal level was raised.

The grout composition used in the borehole annulus consists of approximately 35 100-lb

bags of Type V Portland cement, one 50-lb bag of bentonite powder, and one 80-lb bag

of calcium chloride pellets mixed with potable water to produce approximately

400 gallons of grout. The first lift of grout was pumped down the tremie pipe and

allowed to harden for 24 hours. The remaining grout was pumped down the tremie pipe

in 400 gallon batches. The tremie pipe was raised after the pumping of each batch of

grout. After the grout hardened, the annulus was topped off with additional grout and

a protective surface casing with locking cap was installed. The subsurface well

construction activities were completed on October 7, 1991. The mortar collar, mortar

blanket, and steel guard posts were installed at a later date.

The well casing and screen has been subsequently tested for straightness and possible

damage by passing a bailer through the entire length. No problems were encountered

in the bailer test. The location and elevation of the well have been surveyed (see

Appendix E).

22907A-22327/M.J 02-28-92/RPT 5-4
GEOLOGIC LOG WELL COMPLETION

Al TFRATIHN AMH ""^

MINERALIZATION

FAULTS AND 1

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Job No. : 22327

Prepared by : D.X.B.

Date : 11/14/91

^-16" ID SURFACE CASING

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GEOLOGIC AND WELL

COMPLETION LOGS

BBW-3

YAK TUNNEL OPERABLE UNIT £*

FIG. 5-1
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6.0

INSTALLATION OF BBW-4

6.1 DRILLING SUMMARY

The drilling of monitoring well BBW-4 was conducted according to Standard Operating

Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well Installation in

Bedrock. A site-specific summary of the BBW-4 drilling follows.

Borehole drilling for Monitoring Well BBW-4 started on September 18 1991 and core

drilling at the bottom of the hole was finished on September 23, 1991. Surface casing

was installed to 19 feet below ground surface using the air rotary drilling method and

a 20.5-inch diameter tricone bit. The main bore from the bottom of the surface casing

to 1224 feet below ground surface was drilled by the rotary dual-wall air

reverse-circulation method with a downhole hammer and a 8.5-inch diameter bit. The

lower part of the hole, from 1224 feet to the total depth of 1227 feet, was drilled with

a 6-inch OD diamond coring bit with a 15-foot-long core barrel, using air and water as

the drilling fluid.

Air rotary drilling for the surface casing was accomplished without difficulty. Drilling

the main part of the borehole with the reverse-circulation downhole hammer proceeded

normally, except that the downhole hammer iced up at approximately 285 below ground

surface. The hammer was tripped out of the hole to thaw before drilling was resumed.

Drilling was intermittently delayed at depths below 550 feet because water storage and

transport capacity was insufficient to handle the large quantities of water produced by

drilling in the aquifer. Due to the depth of the hole and the large quantities of water

produced, an auxiliary compressor was attached at approximately 1070 feet. Core

drilling proceeded quickly for the first foot of drilling, but slowed abruptly and reached

refusal at less than three feet from the starting point. Approximately 2 feet of the core

was recovered.

After the core barrel was removed from the hole, a wireline lowered to check the

condition of the hole found the hole to be obstructed at a depth of 850 feet. A

22907A-22327/R2.6 02-05-92/RPT 6-1
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7-7/8-inch tricone bit tripped into the hole was unsuccessful in drilling through the

obstruction. The tricone bit was tripped out, and an 8-inch OD open-face drill bit was

then tripped into the hole. The open face bit got through the obstruction at 850 feet,

but lost circulation at 900 feet. The open face bit was tripped out of the hole and the

7-7/8-inch tricone bit was tripped back into the hole. The tricone bit drilled through

newly collapsed material to a depth of 895 feet, where circulation was lost. The tricone

bit was tripped back up the hole and the open face bit was once again tripped into the

hole. Obstructions at 790 and 900 feet were removed with the open face bit and the

hole was cleared to a depth of 1205 feet. The bit was pulled up to a depth of 995 feet

to allow geophysical logging and the installation of the well.

6.2 GEOLOGIC CONDITIONS

A summary of the geologic conditions encountered in the BBW-4 borehole follows.

Detailed geologic information is contained in Appendix A - Field Boring Logs.

The BBW-4 borehole is located adjacent to Weston Fault at eastern edge of the Breece

Hill stock. The first 5 feet of the hole were drilled in a colluvium of weathered rock of

the Gray Porphyry group. The remainder of the hole, to a total depth of 1227 feet, was

drilled in the Gray Porphyry of the Breece Hill stock. The porphyry is moderately to

intensely altered to sericite throughout the length of the hole. Sericite/chlorite

alteration is common locally. Some minor argillic alteration occurs locally in conjunction

with the sericitic alteration. Disseminated pyrite is ubiquitous, forming 1 percent to

5 percent of the rock volume. Veinlets of pyrite and quartz with pyrite forming as much

as 25 percent of the rock volume occur locally.

Minor faults were indicated during drilling by an increased content of clay and fines in

the drill cuttings. Unusually large angular fragments in the drill cuttings may also

indicate fractures. The small faults appear to be widely separated within the drilled

interval. Limonite (oxidation) does not occur in the apparent fractures below a depth

of 875 feet. One fracture occurring at 895 feet had a 3-inch open space that the drill

string penetrated without hammering. Drill core from the 1224 to 1227 foot interval

exhibits numerous small fractures.

22907A-22327/R2.6 02-05-92/RPT 6-2
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6.3 SELECTION OF SCREENED INTERVAL

Water production was recorded during drilling by measuring the amount of water

produced by air lifting. Flow measurements were taken at 800 feet and 900 feet and

every 20 feet beginning at 1005 feet. In addition, specific conductivity and pH were

measured in the produced water. Approximately 15 to 20 gallons per minute of water

was produced until a depth of 1065 feet, and then production began to gradually increase

to 50 gallons per minute at 1205 feet. Specific conductivity and pH also increased from

1065 to 1205 feet.

The following downhole geophysical logs were run in BBW-4:

Temperature - fluid resistivity

16"-64" normal resistivity, SP and IP

Caliper

Full wave-form sonic

Borehole deviation

Acoustic televiewer

The results of drilling, water measurements and downhole geophysics suggested the

presence of a significant fracture zone from approximately 1155 feet and 1170 feet. The

acoustic televiewer and caliper logs showed the fracture zone most clearly. The

televiewer log showed a steeply north-dipping fracture. Based on the logs and geologic

data, the screened interval was selected to be 1155 to 1195 feet. The filter pack was

extended 15 feet above the screened interval to capture flow from other producing

fractures and to protect the screen from the bentonite seal.

6.4 WELL COMPLETION

The installation of monitoring well BBW-4 was conducted according to Standard

Operating Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well

Installation in Bedrock. A site-specific summary of the BBW-4 well installation follows.

More detailed well installation data is presented in Appendix D - Well Completion Logs.

22907A-22327/R2.6 02-05-92/RPT 6-3
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Subsurface installation of monitoring well BBW-4 commenced on September 25, 1991.

The tremie pipe and well construction materials were decontaminated prior to well

installation according to SOP No. 1 - Decontamination. This well was installed through

the inner annulus of the drill string which was hung to a depth of 995 feet below ground

surface.

Forty feet of 2-inch ID, 0.05-inch slot, wire wound, channel packed stainless steel screen

was used for this well. The well screen was capped on the bottom, attached to the well

casing, and set at a depth of 1197 to 1157 feet below ground surface. The lower part of

the well casing is 720 feet of flush-threaded 2-inch ID Schedule 10 stainless steel casing.

The upper 440 feet of well casing consists of flush-threaded 2-inch ID Schedule 80

low-carbon steel pipe. Centralizers were placed at the top and the bottom of the well

screen, and at two approximately 100-foot intervals above the well screen. Additional

centralizers were not used due to the centralizing effect of installing the well through the

drill pipe. After the well string was lowered, the tremie pipe was lowered through the

drill pipe to an approximate depth of 1150 feet. Neither the tremie pipe nor the well

screen/casing encountered any obstructions as in the open hole below the drill string.

The bottom of the hole from 1227 to 1202 feet below ground surface is filled with

natural collapse rubble from the walls of the borehole. The 8 X 12 mesh Colorado

Silica Sand filter pack was installed from 1202 to 1142 feet by pumping the sand down

the tremie pipe with potable water. The tremie pipe was raised incrementally as the

filter pack level was raised. The bentonite seal was emplaced between 1142 and

approximately 1040 feet by pumping a bentonite powder/potable slurry water down the

tremie pipe and incrementally raising the tremie as the bentonite seal level was raised.

The bentonite seal was allowed to set for 12 hours before placement of the first stage

of grout.

The grout composition used in the borehole annulus consists of approximately 35 100-lb

bags of Type V Portland cement, one 50-lb bag of bentonite powder, and one 80-lb bag

of calcium chloride pellets mixed with potable water to produce approximately

400 gallons of grout. The bottom of the drill string was raised to 895 feet before the

grout was installed. The first lift of grout was pumped down the tremie pipe and

allowed to harden over the four day shift break. Prior to grouting the remainder of the

22907A-22327/R2.6 02-05-92/RPT 6-4
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annuhis, the drill pipe was removed from the hole and the tremie pipe was re-inserted.

The remaining grout was pumped down the tremie pipe in 400 gallon batches. The

tremie pipe was raised after the pumping of each batch of grout. After the grout

hardened, the annulus was topped off with additional grout and a protective surface

casing with locking cap was installed. The subsurface well construction activities were

completed on October 1,1991. The mortar collar, mortar blanket, and steel guard posts

were installed at a later date.

The well casing and screen has been subsequently tested for straightness and possible

damage by passing a bailer through the entire length. No problems were encountered

in the bailer test. The location and elevation of the well have been surveyed (see

Appendix E).

22907A-22327/R2.6 02-2J-M/RPT 6-5
GEOLOGIC LOG WELL COMPLETION

ALTERATION AND

MINERALIZATION

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NATURAL COLLAPSE RUBBLE

SCALE: 1" = 150'

Job No. : 22327

Prepared by : D.X.B.

Date : 11/14/91

GEOLOGIC AND WELL

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COMPLETION LOGS

BBW 4

YAK TUNNEL OPERABLE UNIT ^

FIG. 6-1
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7.0

INSTALLATION OF BBW-5

7.1 DRILLING SUMMARY

The drilling of monitoring well BBW-5 was conducted according to Standard Operating

Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well Installation in

Bedrock. A site-specific summary of the BBW-5 drilling follows.

Borehole drilling for Monitoring Well BBW-5 started on October 6, 1991 and finished

on October 12,1991. Surface casing was installed to 20 feet below ground surface using

the air rotary drilling method and a 20.5-inch diameter tricone bit. The main bore from

the bottom of the surface casing to a total depth of 902 feet was drilled by the rotary

dual-wall air reverse-circulation method with a downhole hammer and a 8.5-inch

diameter bit. Core drilling was not used in this borehole.

Air rotary drilling for the surface casing was accomplished without difficulty. Drilling

the main part of the borehole with the reverse-circulation downhole hammer proceeded

normally.

After the downhole hammer was removed from the hole, a wireline lowered into the

hole indicated and obstruction at 400 feet below ground surface. A specially constructed

8-inch open face/tricone bit was tripped down the hole and cleared all obstructions to

a depth of 885 feet. The bit was pulled up to a depth of 540 feet to allow geophysical

logging and the installation of the well. The geophysical hole deviation probe indicated

a possible obstruction at a depth of 823 feet.

12 GEOLOGIC CONDITIONS

A summary of the geologic conditions encountered in the BBW-5 borehole follows.

Detailed; geologic information is contained in Appendix A - Field Boring Logs.

22907A-22327/R2.7 02-05-92/RPT 7-1
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Unlike the other boreholes, the BBW-5 borehole site is not located adjacent to a major

fault. However the borehole is located near the northern terminus of the Silent Friend

Fault. The top 25 feet of the borehole was drilled through Quaternary colluvium

composed primarily of fragments of Belden Formation sandstone. Between the base of

the colluvium and the total depth of 900 feet, the entire local Paleozoic stratigraphic

section is represented. The stratigraphic units include the Belden Formation, the

Leadville Limestone, the Dyer Dolomite, the Parting Quartzite, the Manitou Formation,

the Peerless Formation, and the Sawatch Quartzite. The borehole was terminated within

the Sawatch Quartzite. The Gray Porphyry forms several sills within the stratigraphic

section. The porphyry is moderately to strongly sericitized, and generally contains a

trace of disseminated pyrite.

The majority of the faults indicated by drilling occur in the Leadville Limestone, the

Dyer Dolomite, and the Sawatch Quartzite. These faults were indicated during drilling

by an increased content of clay and fines in the drill cuttings. Unusually large angular

fragments in the drill cuttings may also indicate fractures. Limonite (oxidation) does not

occur in the apparent fractures below 730 feet. Carbonate rocks are silicified along

several of the fractured areas.

Sulfide mineralization occurs in two intervals in the borehole. In the interval from 760

to 790 feet below ground surface, several percent of combined pyrite, sphalerite, and

galena occurs in the Peerless Formation. In the 5-foot interval below 770 feet, total

sulfides comprise 10% of the rock volume. The interval from 815 to 900 feet contains

a trace to 4% of combined pyrite, sphalerite, and galena. RecrystaUized dolomite also

occurs locally within this zone.

7.3 SELECTION OF SCREENED INTERVAL

Water production was recorded during drilling by measuring the amount of water

produced by air lifting. Water production was measured every 100 feet from 205 feet

to 725 feet and every 20 feet thereafter to 900 feet. In addition, pH and specific

conductivity were measured in the produced water. Approximately seven to twelve

gallons per minute of water were produced in the interval between 205 and 505 feet

when the flow ceased. Flow began again at approximately 705, producing four to eight

22907A-22327/R2.7 02-05-92/RPT 7-2
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gallons per minute. Flow increased to approximately 25 gallons per minute at 845 feet.

The specific conductivity also decreased in the samples from 845 to 905 feet.

The following downhole geophysical logs were run in BBW-5:

Temperature - fluid resistivity

16"-64" normal resistivity, SP and IP

Caliper

Full wave-form sonic

Borehole deviation

Acoustic televiewer

The results of drilling, water measurements and downhole geophysics suggested the

presence of significant fracture zones at approximately 810, 840 and 855 feet. The

acoustic televiewer, caliper and temperature\fluid resistivity logs showed the waterproducing fractures most clearly. Based on these data, the screened interval was selected

to be 820 to 860 feet. The filter pack was extended 15 feet above the screened interval

to capture flow from the fracture zone at 810 feet and to protect the screen from the

bentonite seal.

7.4 WELL COMPLETION

The installation of monitoring well BBW-5 was conducted according to Standard

Operating Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well

Installation in Bedrock. A site-specific summary of the BBW-5 well installation follows.

More detailed well installation data is presented in Appendix D - Well Completion Logs.

Subsurface installation of monitoring well BBW-5 commenced on October 9,1991. The

tremie pipe and well construction materials were decontaminated prior to well

installation according to SOP No. 1 - Decontamination. This well was installed through

the inner annulus of the drill string which was hung to a depth of 540 feet below ground

surface.

22907A-22327/R2.7 02-05-92/WT . 7-3
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Forty feet of 2-inch ID, 0.05-inch slot, wire wound, channel packed stainless steel screen

was used for this well. The well screen was capped on the bottom, attached to the well

casing, and set at a depth of 858 to 818 feet below ground surface. The lower part of

the well casing consists of 120 feet of flush-threaded 2-inch ID Schedule 10 stainless steel

casing. The upper 700 feet of well casing consists of flush-threaded 2-inch ID Schedule

80 low-carbon steel pipe. Centralizers were placed at the top and the bottom of the well

screen, and at three approximately 100-foot intervals above the screen. Additional

centralizers were not used due to the centralizing effect of installing the well through the

drill pipe. After the well string was lowered, the tremie pipe was lowered through the

drill pipe to a depth of 834 feet. Neither the tremie pipe nor the well screen/casing

encountered any obstructions in the open hole below the drill string.

The bottom of the borehole from 902 to 877 feet below ground surface is filled with

natural collapse rubble from the walls of the borehole. The 8 X 12 mesh Colorado

Silica Sand filter pack was installed from 877 to 802 feet by pumping the sand down the

tremie pipe with potable water. The tremie pipe was raised incrementally as the filter

pack level was raised. The bentonite seal was emplaced between 802 and approximately

660 feet by pumping a bentonite powder/potable water slurry down the tremie pipe and

incrementally raising the tremie as the bentonite seal level was raised. The bentonite

seal was allowed to set for 12 hours before placement of the first stage of grout.

The grout composition used in the borehole annulus consists of approximately 35 100-lb

bags of Type V Portland cement, one 50-lb bag of bentonite powder, and one 80-lb bag

of calcium chloride > pellets mixed with potable water to produce approximately 400

gallons of grout. The first lift of grout was pumped down the tremie pipe and allowed

to harden for 24 hours.

When the first lift of grout had hardened for 24 hours, it was found that the tremie pipe

was hung up in the borehole. The end of the tremie pipe was 600 feet below ground

surface and the grout was tagged through the tremie pipe at 585 feet below ground

surface. The annulus was bridged off at 400 feet. Since the tremie pipe could not be

removed from the caved section of the borehole, the tremie pipe was split with an

explosive charge at a depth of 545 feet. Two 400-gallon batches of grout were pumped

through the split in the tremie pipe.

22907A-22327/R2.7 02-OJ-92/RPT 7-4
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By using a wrench at the surface, 290 feet of the tremie pipe were recovered from the

hole. The remaining 310 feet of tremie pipe, from 600 to 290 feet below ground surface,

were cemented into the annulus.

Another tremie pipe was lowered to a depth of 400 feet into the borehole. The

remaining grout was pumped down the new tremie pipe in 400-gallon batches. The

tremie pipe was raised after the pumping of each batch of grout. After the grout

hardened, the annulus was topped off with additional grout and a protective surface

casing with locking cap was installed. The subsurface well construction activities were

completed on September 17, 1991. The mortar collar, mortar blanket, and steel guard

posts were installed at a later date.

Following well completion but before the installation of the protective casing, a water

level probe was lowered into the well to check the water level and the depth at the

bottom of the well. The probe would not go all the way to the bottom of the well, and

when removed, the probe appeared to have bentonite on it. Additional testing was

conducted as discussed below.

The well casing and screen has been subsequently tested for straightness and possible

by passing a bailer through the entire length. No problems were encountered in the

bailer test. The location and elevation of the well have been surveyed (see Appendix E).

7.5 ADDITIONAL GEOPHYSICAL LOGGING

EPA was notified of the presence of the bentonite in the well and was present during

the initial bailing of the well, when the bentonite was removed. EPA raised concerns

over the integrity of the well and requested that a natural gamma log be made of BBW5. The downhole geophysical logging equipment was mobilized to the site and a natural

gamma log, 4-pi density log and downhole video were made. The logs indicate that the

well is intact and the screened interval undamaged. The video log also showed the

presence of minor sediment in the well screen.

22907A-22327/R2.7 02-28-92/WT 7-5
GEOLOGIC L

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GEOLOGIC AND WELL

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BBW-5

YAK TUNNEL OPERABLE UNIT ^

FIG. 7-1
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8.0

INSTALLATION OF BBW-7

8.1 DRILLING SUMMARY

The drilling of monitoring well BBW-7 was conducted according to Standard Operating

Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well Installation in

Bedrock. A site-specific summary of the BBW-7 drilling follows.

Borehole drilling for Monitoring Well BBW-7 started on September 5, 1991 and was

finished on September 8, 1991. Surface casing was installed to 12 feet below ground

surface using the air rotary drilling method and a 20.5-inch diameter tricone bit. After

the surface casing, drilling resumed with by the rotary dual-wall air reverse-circulation

method with a downhole hammer and a 8.5-inch diameter bit.

At a depth of 20 feet below ground surface, the hammer was removed and the drill bit

was changed to a 7-7/8-inch tricone bit. The tricone bit was used to drill to a depth of

78 feet, where 6-inch OD core drilling began. Core drilling proceeded from 78 to

107 feet below ground surface. Tricone drilling resumed at 78 feet, the core hole was

reamed to 107 feet, and tricone drilling continued to 278 feet. The bottom of the cored

hole was cored from 278 to 290 feet. After coring , the tricone bit was used to ream the

cored hole to a total depth of 291 feet.

Air rotary drilling for the surface casing was accomplished without difficulty. Drilling

the main part of the borehole with the reverse-circulation rotary tricone proceeded

normally. Core drilling recovered approximately 90% of the core in the 78 to 107-foot

depth interval, and 75% of the core in the 278 to 290-foot interval.

8.2 GEOLOGIC CONDITIONS

A summary of the geologic conditions encountered in the BBW-7 borehole follows.

Detailed geologic information is contained in Appendix A - Field Boring Logs.

22907A-22327/R2.8 02-05-92/RJT 8-1
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The BBW-7 borehole is located adjacent to the Iron Fault. The first few feet of the hole

were drilled in a colluvium of weathered rock of the Pando Porphyry. The remainder

of the hole, to a total depth of 291 feet, was drilled within the Pando Porphyry. The

porphyry is moderately to intensely altered to sericite throughout the length of the hole.

Some argillic alteration occurs locally in conjunction with the sericitic alteration.

Fracture coatings of iron and manganese oxides are common throughout the length of

the borehole. Traces of pyrite and calcite along fractures occur locally.

Small fractures occur throughout the borehole, evidenced by oxide-coated fracture

surfaces brought up with the drill cuttings.

8.3 SELECTION OF SCREENED INTERVAL BBW-7

Water production was observed during drilling of BBW-7. Water flow began at 161 feet

below ground surface and appeared to increase with depth.

The following downhole geophysical logs were run in BBW-7:

Temperature - fluid resistivity

16"-64" normal resistivity, SP and IP

Caliper

Full wave-form sonic

Gamma and neutron

Borehole deviation

Acoustic televiewer

The results of drilling and downhole geophysics suggested the presence of a significant

fracture zone from approximately 235 feet to 260 feet. The acoustic televiewer log

showed the fracture zone most clearly. Based on these data, the screened interval was

selected to be 250 to 290 feet. The filter pack zone was extended 18 feet above the

screen to capture water from the fracture zone from 235 feet to the top of the screen.

22907A-22327/R2.8 02-05-92/RPT 8-2
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8.4 WELL COMPLETION

The installation of monitoring well BBW-7 was conducted according to Standard

Operating Procedure (SOP) No. 22 - Groundwater Piezometer/Monitoring Well

Installation in Bedrock. A site-specific summary of the BBW-7 well installation follows.

More detailed well installation data is presented in Appendix D - Well Completion Logs.

Subsurface installation of monitoring well BBW-7 commenced on September 8, 1991.

The tremie pipe and well construction materials were decontaminated prior to well

installation according to SOP No. 1 - Decontamination. The tremie pipe was lowered

down the open hole to an approximate depth of 280 feet. Forty feet of 2-inch ID, 0.05-

inch slot, wire wound, channel packed stainless steel screen was used for this well. The

well screen was capped on the bottom, attached to the well casing, and set at a depth

of 290 to 240 feet. The lower part of the well casing consists of 120 feet of flushthreaded 2-inch ID Schedule 10 stainless steel casing. The upper 130 feet of well casing

consists of flush-threaded 2-inch ID Schedule 40 low-carbon steel pipe. Centralizers

were placed at the top and the bottom of the well screen, and at approximately 100-foot

intervals along the length of the well casing. Neither the tremie pipe nor the well

screen/casing encountered any obstructions as they were lowered down the open hole.

The 8 X 12 mesh Colorado Silica Sand filter pack was installed from 291 to 232 feet

below ground surface by pumping the sand down the tremie pipe with potable water.

The tremie pipe was raised incrementally as the filter pack level was raised. The

bentonite seal was emplaced between 232 and 132 feet by pumping a mixture of 3/8-inch

bentonite chips and potable water down the tremie pipe and incrementally raising the

tremie as the bentonite seal level was raised.

The grout composition used in the borehole annulus consists of approximately 35 100-lb

bags of Type V Portland cement, one 50-lb bag of bentonite powder, and one 80-lb bag

of calcium chloride pellets mixed with potable water to produce approximately

400 gallons of grout. Because the depth to the bentonite seal was only 131 feet below

ground surface, grouting by lifts was not required. The grout was pumped down the

tremie pipe and allowed to harden. The tremie pipe was raised after pumping the first

batch of grout. After the grout hardened, the annulus was topped off with additional

22907A-22327/R2.8 02-Q5-92/RPT 8-3
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grout and a protective surface casing with locking cap was installed. The subsurface well

construction activities were completed on September 9,1991. The mortar collar, mortar

blanket, and steel guard posts were installed at a later date.

The well casing and screen has been subsequently tested for straightness and possible

damage by passing a bailer through the entire length. No problems were encountered

in the bailer test. The location and elevation of the well have been surveyed (see

Appendix E).

22907A-22327/R2.8 02-28-92/WT 8-4
Woodward-Clyde Consultants

GEOLOGIC LOG

12

WELL COMPLETION

QUATERNARY

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Job No, : 22327

Prepared by : D.X.B.

Date : 11/14/91

GEOLOGIC AND WELL

COMPLETION LOGS

BBW-7

YAK TUNNEL OPERABLE UNIT

FIG. 8-1
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9.0

WELL DEVELOPMENT

9.1 DEVELOPMENT PROCEDURES

Development of the six piezometers was conducted according to the procedures specified

in SOP No. 4 - Monitoring Well Development. The well was surged and water removed

using a decontaminated stainless steel bailer on a wireline. The bailer was

approximately 10 feet long and 1-1/4 inches in diameter. A minimum of 10 well

volumes were removed from each well. Temperature, pH, and specific conductivity were

measured during the development process. Development logs, including the

measurement of temperature, pH, and specific conductivity, are presented in Appendix

D. Due to the large quantities of water that required removal, a request was made to

EPA to allow the use of air-lifting as a development method in wells with sufficient

water. EPA agreed to the modification.

The air-lift development employed the use of the dual-tube method. Air was introduced

into the well using a 1-inch diameter decontaminated steel tube. The 2-inch diameter

well riser served as the second tube. The injection tube was set at least 50 feet above

the top of the sand pack and the air was injected from the compressors on the drill rig.

At no time was the water level allowed to fall below the end of the injector pipe. Only

wells with greater than 100 feet of water in the casing were developed using the air-lift

method. Approximately nine well volumes were removed using the air-lift method. The

tenth well volume was removed by bailing. At EPA's request, dissolved oxygen and field

redox were measured during airlift development.

92 DEVELOPMENT OF BBW-1

Air-lift development of BBW-1 began on October 21, 1991 and was completed in

approximately six hours. The injector tube was set at approximately 700 feet below the

surface. The water was turbid at the start of air-lifting and slightly turbid when air-lifting

was completed after removal of approximately 640 gallons of water. Approximately 100

22907A-22327/R2.9 02-28-92/RPT 9-1
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gallons of water were produced per hour. The temperature, pH and conductivity did not

stabilize during airlifting.

Bailer development started on October 31, 1991 and was completed on November 1,

1991. Approximately 75 gallons of water were removed. The water was very turbid at

the beginning of bailing and was slightly turbid at the end of bailing. The temperature

stabilized at 7.5°C, the pH at 9.45 and the conductivity at 360 uS/cm (equivalent to

mmhos/cm).

9.3 DEVELOPMENT OF BBW-2

Air-lift development of BBW-2 began on October 21, 1991 and was completed in

approximately two hours. The injector tube was set at approximately 300 feet below the

surface. The water was turbid at the start of airlifting and clear when air-lifting was

completed after removal of approximately 620 gallons of water. Approximately 300

gallons of water were produced per hour. The temperature, pH and conductivity did not

stabilize during airlifting.

Bailer development was completed on November 3, 1991. Approximately 75 gallons of

water were removed. The water was very turbid at the beginning of bailing and was

slightly turbid at the end of bailing. The temperature stabilized at 7.3°C. The pH was

stable at 6.2 but problems were encountered with the pH meter. The conductivity varied

between 500 and 600 uS/cm.

9.4 DEVELOPMENT OF BBW-3

Air-lift development of BBW-3 began on October 20, 1991 and was completed in

approximately twelve hours. The injector tube was set at approximately 660 feet below

the surface. The water was turbid at the start of airlifting and remained turbid when airlifting was completed after removal of approximately 380 gallons of water.

Approximately 30 gallons of water were produced per hour. The temperature, pH and

conductivity did not stabilize during airlifting.

22907A-22327/R2.9 02-28-92/RPT 9-2
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Bailer development was completed on October 30, 1991. Approximately 72 gallons of

water were removed. The water was very turbid throughout bailing. The temperature

varied from 4.8 to 6.1°C. The pH stabilized at 7.4 and the conductivity stabilized at 290

uS/cm.

9.5 DEVELOPMENT OF BBW-4

Air-lift development of BBW-4 began on October 20, 1991 and was completed in

approximately three hours. The injector tube was set at approximately 1090 feet below

the surface. The water was turbid at the start of air-lifting and clear when air-lifting was

completed after removal of approximately 800 gallons of water. Approximately 260

gallons of water were produced per hour. The temperature, pH and conductivity did not

stabilize during air-lifting.

Bailer development started on October 21, 1991 and was completed on October 23,

1991. Approximately 92 gallons of water were removed. The water was turbid

throughout bailing. The temperature stabilized at 7.8°C, the pH at 8.2 and the

conductivity at 235 uS/cm.

9.6 DEVELOPMENT OF BBW-5

BBW-5 was not developed using air-lifting. Bailer development started on October 19,

1991. Four different periods of bailing occurred at BBW-5. The first period was

October 19-20. Ten well volumes of water (100 gallons) were removed from the well.

The first several bailer-fulls produced a diluted bentonite fluid. As development

proceeded, the bentonite disappeared. The temperature stabilized at 10.2°C, the pH at

7.5 and the conductivity at 530 uS/cm.

At the request of EPA, due to their concern over the bentonite in the well, the well was

bailed again on October 23 and 24. This time 75 gallons of turbid water were removed

from the well. Bentonite was not encountered during bailing. The temperature

stabilized at 9.3°C, the pH at 7.5 and the conductivity at 480 uS/cm. The well was bailed

again of October 29, when 40 gallons were removed, and on November 4 when 10

gallons were removed. Field parameters were not measured during these additional events.

22W7A-22327/R2.9 02-28-92/RPT 9-3
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9.7 DEVELOPMENT OF BBW-7

BBW-7 was not developed using air-lifting. Bailer development started on November

2, 1991. Ten well volumes of water (110 gallons) were removed from the well. As

development proceeded, the water went from turbid to slightly turbid. The temperature

stabilized at approximately 5.5°C, the pH at 6.5 and the conductivity at 1300 uS/cm.

22907A-22327/R2.9 02-28-92/RPT 9-4
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10.0

SUMMARY OF CHANGES FROM THE WORK PLAN/SAP

The drilling and development of the monitoring wells described in this document were

completed according to the methods and procedures described in the Work Plan, Yak

Tunnel Operable Unit (Res-ASARCO 1990b), the Sampling and Analysis Plan (SAP),

Yak Tunnel Operable Unit (Res-ASARCO 1990c) and the Technical Memorandum for

Piezometers and Monitoring Wells, Yak Tunnel Operable Unit (Res-ASARCO 1991).

Where warranted by conditions in the field, modifications were made to the SOPs to

facilitate completion of the program. All changes were approved by the EPA field

representative prior to implementation.

10.1 CHANGES IN THE WORK PLAN

The Work Plan (Res-ASARCO 1990b) presented the approach to the location and

drilling of the borings. The major change to the Work Plan was in the locations of the

wells. The locations of the wells were described in the Selected Remedy Component

Change Proposal (SRCCP)(Res-ASARCO 1990a) as described in Section 1.0 above.

10.2 CHANGES IN THE SAMPLING AND ANALYSIS PLAN

The major changes to the Sampling and Analysis Plan (Res-ASARCO 1990c) relate to

field modifications to two SOPs. Five field changes were made to

SOP No. 22 and one change was made to SOP No. 4. The specific field changes are

described below.

Field Change YAK-001 - In SOP No. 22, a period of 12 hours will be allowed between

the placement of a bentonite slurry seal and installation of the first stage of grout. A

period of 30 minutes will be allowed between the placement of a bentonite chip or pellet

seal and installation of the first stage of grout. Approved by K. Hemlein, EPA's field

representative, on September 5, 1991.

22907A-22327/R2.10 02-05-92/RPT 1Q-1
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Field Change YAK-002 - In SOP No. 22, following well completion, a 6-inch diameter

steel surface casing with a hinged lockable cover will be imbedded three feet into the

grout. The surface casing will project approximately two feet above the ground surface.

Approved by K. Hemlein, EPA's field representative, on September 5, 1991.

Field Change YAK-003 - In SOP No. 22, following well completion, the protective casing

and posts will be painted to make them visible,labeled (with white paint) with the well

designation, and locked. Red paint was used to paint the protective casing and posts.

Approved by K. Hemlein, EPA's field representative, on September 5, 1991.

Field Change YAK-004 - In SOP No. 22, for BBW-7 only, schedule 40 low-carbon steel

was used for casing above the water table to ground surface. Schedule 80 steel was used

above the water table in the other wells. Approved by K. Hemlein, EPA's field

representative, on September 11, 1991.

Field Change YAK-005 - In SOP No. 22, a 0.5-foot thick mortar blanket will extend

approximately 2-feet radially from the protective casing to provide an effective surface

protection. Approved by K. Hemlein, EPA's field representative, on September 12,

1991.

Field Change YAK-006 - In SOP No. 4, air-lift development methods may be used in

wells with greater than 100 feet of water in the well. See Section 9.0 for additional

information, a 0.5-foot thick mortar blanket will extend approximately 2-feet radially

from the protective casing to provide an effective surface protection. Approved by

EPA's field and office representatives, on October 2, 1991.

22907A-22327/R2.10 02-05-92/RPT 10-2
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11.0

DISCUSSION OF HYDROGEOLOGIC CONDITIONS

11.1 GENERAL HYDROGEOLOGIC CONDITIONS

The hydrogeologic conditions encountered during the drilling of the Yak Tunnel O.U.

monitoring wells were generally those expected by the hydrogeologic interpretation

presented in the SRCCP (Res-ASARCO 1990a) and the Technical Memorandum for

Piezometers and Monitoring Wells (Res-ASARCO 1991). Several variations in

hydrogeologic conditions from the previous hydrogeologic interpretations were revealed

during the course of drilling, well installation and development of the monitoring wells.

Water was generally produced from fracture zones within the bedrock, as expected,

however, the distribution of faults and fractures in the bedrock was greater than

expected. Static water levels and water quality in the wells were different than expected.

The distribution of faults and fractures in the bedrock was greater than had been

expected. Surface seismic refraction methods produced cross-sections of the subsurface

in the vicinity of the monitoring wells. These seismic sections indicate more moderateand large-sized faults and fractures than were reported in the available literature.

Observations made during drilling of the well boreholes suggested the presence of

numerous moderate- and large-sized fractures, and the presence of the faults indicated

by the seismic refraction was confirmed. The downhole geophysical logs, particularly the

acoustic televiewer log, clearly showed the high density of small- to large-sized faults and

fractures in the lower sections of the monitoring well boreholes. The greater than

expected occurrence of faults in the vicinity of the monitoring wells suggests that the

bedrock aquifer is more permeable and interconnected than was previously thought.

Static water levels in the wells BBW-1, BBW-2, BBW-3, and BBW-4 are higher than

expected. The static water levels were expected to occur near the level of the Yak

Tunnel (Res-ASARCO 1990a). The observed water levels in these wells range from

approximately 300 to 500 feet above the Yak Tunnel level. The static water level in well

BBW-2 is unusually close to the ground surface, but there is evidence of abundant

shallow-level groundwater in the Whites Gulch drainage where BBW-2 is located. The

22907A-22327/R2.11 02-05-92/RPT 11-1
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static water levels in BBW-1 through BBW-4 indicate a steeper water level gradient

toward the Yak Tunnel than had been expected. The large columns of water hi these

wells require considerable effort to purge the required water volumes from the wells

during development and sampling.

Static water levels in wells BBW-5 and BBW-7 are closer to expected levels. The

observed static water level in BBW-5 is approximately 10 feet below the Yak Tunnel

level. The lower-than-expected water level in this well is probably due to the proximity

of the well to mine workings which drain directly into the Yak Tunnel. The observed

static water level in well BBW-7 is 135 feet below the level of the Yak Tunnel. The

BBW-7 water level was expected to be below the Yak Tunnel level based on the location

of the well.

Water quality parameters measured in the field after well development by bailing are

shown in Appendix D. The pH values are generally higher than expected, indicating that

acid groundwater is not being generated in the bedrock aquifer peripheral to the Yak

Tunnel at the same elevation as the Yak Tunnel.

112 WELL BBW-1 HYDROGEOLOGY

The first groundwater encountered during the drilling of BBW-1 was 310 to 315 feet

below ground surface. The inflow temporarily ceased as drilling progressed beyond this

point. Water was encountered again at 725 to 885 feet below ground surface, where

airlifting produced 3 to 4 gpm. The specific conductivity of the 725 to 885 foot interval

water generally increases from 2,060 to 2,460 uS/cm (equivalent to umhos/cm) with

depth. A significant fracture encountered at a depth of approximately 890 feet

temporarily reduced drill water circulation, but subsequently increased the airlifted flow

rate of water from the. borehole. At a depth of 905 feet, airlift flow increased to 4.5 gpm

and specific conductivity increased slightly.

The static water level after completion of well BBW-1 is 470 feet below ground surface,

which corresponds to 380 feet above the Yak Tunnel level closest to that well.

Groundwater encountered in the 310 to 315-foot interval probably represents flow along

fractures in the unsaturated zone.

22907A-22327/R2.11 02-24-W/WT 11-2
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11.3 WELL BBW-2 HYDROGEOLOGY

The first groundwater encountered during the drilling of BBW-2 was during the

installation of the surface casing. The next zone of groundwater was encountered

approximately 175 to 205 feet below ground surface. An airlift of the water at 205 feet

produced 3 to 4 gpm. At a depth of 305 feet, airlifting produced only a trace of water.

The fractured interval from 345 to 430 feet below ground surface produced from 4.5 to

8 gpm with increasing depth. A water-bearing fracture was intercepted at a depth of 437

feet. Airlifting produced 23 gpm at a depth of 445 feet. The specific conductivity of the

airlifted water decreased from 340 to 253 uS between 345 and 445 feet below ground

surface. The field pH of water airlifted from a depth of 345 feet was 10.3. The pH

dropped to 6.65 at 365 feet, and ranged from 6.46 to 6.65 below a depth of 365 feet.

The static water level after completion of well BBW-2 is 30 feet below ground surface,

which corresponds to 390 feet above the Yak Tunnel level closest to that well.

Groundwater encountered in the intervals above the screened zone probably represent

fracture flows within the saturated zone.

11.4 WELL BBW-3 HYDROGEOLOGY

The first groundwater encountered during the drilling of BBW-3 was approximately 405

feet below ground surface. The flow ceased temporarily as drilling progressed beyond

this point. Airlifting at 625 and 725 feet produced 2 gpm. Water bearing fractures were

intercepted from 730 to 755 feet. Airlift flow rates for 745 and 765 feet were 8.6 and

12 gpm respectively. The specific conductivity of the water decreased with depth from

252 to 238 uS in the 705 to 765-foot interval, and pH ranged from 6.6 to 7.6.

The static water level after completion of well BBW-3 is 516 feet below ground surface,

which corresponds to 340 feet above the Yak Tunnel level closest to that well.

Groundwater encountered at the 405-foot level probably represents flow along a fracture

in the unsaturated zone.

22907A-22327/R2.11 M-24-92/RPT 11-3
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Woodward-Clyde

Consultants

11.5 WELL BBW-4 HYDROGEOLOGY

The first groundwater encountered during the drilling of BBW-4 was 425 feet below

ground surface. More water was encountered at 470 feet, and airlifting at 505 feet

produced 5 gpm. From 540 to 605 feet, the amount of drill circulation water gradually

increased. Airlifting at 605, 705, 805, and 905 feet produced approximately 50 gpm.

Airlift flow decreased to approximately 15 gpm at 1005,1025, and 1045 feet. From 1065

to 1185 feet airlift flow ranged from 25 to 40 gpm. At 1205 and 1225 feet airlifting

produced 50 gpm. Specific conductivity generally increased with depth from 193 to 282

uS in the 825 to 1225 foot interval. The pH in this interval varied irregularly from 5.4

to 7.1.

The static water level after completion of well BBW-4 is 672 feet below ground surface,

which corresponds to 490 feet above the Yak Tunnel level closest to that well.

Groundwater encountered above the 672 foot level probably represents fracture flow

through the unsaturated zone.

11.6 WELL BBW-5 HYDROGEOLOGY

The first groundwater encountered during the drilling of BBW-5 was during the

installation of the surface casing. Water was not encountered again until approximately

7 to 12 gpm was airlifted in the interval from 205 to 505 feet below ground surface. The

flow of v/ater subsequently ceased before a depth of 705 feet. From 765 to 845 feet

deep, airlifting produced 4 to 8 gpm. Large fractures intercepted below 845 feet

increased airlift flow to approximately 25 gpm at 885 to 900 feet below ground surface.

The specific conductivity of the airlifted water ranged from 1006 to 1263 uS in the

interval from 205 to 825 feet below ground surface. In the interval from 845 to 900 feet,

specific conductivity ranged from 522 to 631 uS. The field pH of water airlifted from

the interval from 425 to 900 feet ranged from 8.2 to 8.6.

The static water level after completion of well BBW-5 is 796 feet below ground surface,

which corresponds to 11 feet below the Yak Tunnel level closest to that well.

Groundwater encountered above the 705-foot level probably represents local perched

aquifers or fracture flow in the unsaturated zone.

22907A-22327/R2.11 02-24-92/RPT 11-4
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Woodward-Clyde

Consultants

11.7 WELL BBW-7 HYDROGEOLOGY

The first groundwater encountered during the drilling of BBW-7 was approximately 161

feet below ground surface. The static water level in the 278-foot deep open hole was

measured at 222 feet below ground surface after letting the water level rise for three

hours after drilling.

The static water level after completion of well BBW-7 is 229 feet below ground surface,

which corresponds to 135 feet above the Yak Tunnel level closest to that well.

Groundwater encountered above the 229-foot level probably represents a local perched

aquifer or fracture flow in the unsaturated zone.

22907A-22327/R2.11 02-03-92/RPT 11-5
• Woodward-Clyde

_ Consultants

I

12.0

REFERENCES

I Behre, C.H., Jr. 1953. Geology and Ore Deposits of the West Slope of the Mosquito

_ Range. U.S. Geological Survey Professional Paper 235.

Emmons, S.F., J.D. Irving, and G.F. Laughlin. 1927. Geology and Ore Deposits of the

• Leadville Mining District, Colorado. U.S. Geological Survey Professional Paper

148.

Jonson, D.C. 1955. The Geology of the Resurrection Mine Area, Lake County,

• Colorado. M.S. Thesis. Golden, Colorado. Colorado School of Mines.

_ Klimper, Chuck (ASARCO Black Cloud Mine Engineer). 1990. Personal

| Communication with Woodward-Clyde Consultants.

| Res-ASARCO. 1990a. Selected Remedy Component Change Proposal (SRCCP).

Prepared by Woodward-Clyde Consultants. March 20, 1990.

Res-ASARCO. 1990b. Work Plan, Yak Tunnel Operable Unit, California Gulch Site,

• Leadville, Colorado. Prepared by Woodward-Clyde Consultants. August 1990.

_ Res-ASARCO. 1990c. Sampling and Analysis Plan (SAP), Yak Tunnel Operable Unit,

I California Gulch Site, Leadville, Colorado. Prepared by Woodward-Clyde

Consultants. April, 1990. Revised November, 1990 and March, 1991.

Res-ASARCO. 1991. Technical Memorandum for Piezometers and Monitoring Wells,

I Yak Tunnel Operable Unit, California Gulch Site, Leadville, Colorado. Prepared

by Woodward-Clyde Consultants. August 1991.

• Thompson, T.B. 1974. Cross-sections. Property of ASARCO, Leadville Unit.

I

22907A-22327/R2.12 02-05-92/RPT 12-1
• Woodward-Clyde

_ Consultants

I U.S. Environmental Protection Agency (EPA). 1988. Record of Decision (ROD), Yak

Tunnel Operable Unit, California Gulch Site, Leadville, Colorado. March 29,

• 1988.

U.S. Environmental Protection Agency (EPA). 1989. Record of Decision Modification,

I Yak Tunnel Operable Unit, California Gulch Site, Leadville, Colorado. March

_ 23, 1989.

U.S. Environmental Protection Agency (EPA). 1991 DRAFT. Explanation of Significant

• Differences (ESD), Yak Tunnel Operable Unit, California Gulch Site, Leadville,

Colorado.

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22907A-22327/R2.12 02-05-92/RPT 12-2
I

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• APPENDIX A

• FIELD BORING LOGS

I

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1

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I

229CT7A-22m/R2.TS 02-05-92/RPT
PROJECT NAME A -HOLE

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GRAPHIC LOG

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Woodward-Clyde <Consultants wp PROJECT NAME A.SARC 0 BgW-Q-7

DESCRIPTION

GRAPHIC LOG

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SAMPLES

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REMARKS

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JECT NO 3.23-qT SHEET _LL_ OF
The downhole geophysical logs are included in Borehole Geophysical Log Interpretation

for Yak Tunnel Operable Unit, prepared by COLOG, Inc. and included as Volume II

I

I

i

I

i

of this report.

I

I

I

1

I

I

I

I

I

I

I

I

I

APPENDIX B

DOWNHOLE GEOPHYSICAL LOGS

229CT7A-22321/R2.TS 02-24-92/RPT
IIIfjIIIIIIIII1IIII

APPENDIX C

WELL COMPLETION LOGS

22907A-2::327/R2.TS 02-03-92/RPT
WELL INSTALLATION REPORT

PROJECT

LOCATION

DATE COMPLETED ?-J3-?/ [i« to'l& *t

Ct>(orae/o

WELL NO.

PROJECT NO. A? 3 3-7

PREPARED BY

HEICHT OF SWPKCE CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF SURFACE CASING

HEIGHT OF WELL CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF WELL CASING

ID OF SURFACE CASING AND niAMFTER

'E OF .GROUT SEAL

'3T

e 6-jers'ujg

DEPTH OF SURFACE CASING BELOW GROUND

ID OF INTERMEDIATE CASING AND DIAMETER .

TYPE OF GROUT SEAL

=E OF GROUT SEAL Qffi- &vet

ID OF WELL

fltute -

CASING AND D .? Xt> ^.375 OP

DEPTH OF INTERMEDIATE CASING BELOW GROUND

DIAMETER OF BOREHOLE.

DEPTH OF TOP OF BENTONITE SEAL

E OF BENTONHTE SEAL %" fer1p^;k ft/e Pfua <A('/

noij <r

<><We g«J« (Ale^fKn Btytm^te

DEPTH OF BOHOM OF BENTONfTE SEAL

DEPTH OF TOP OF SAND PACK

TYPE OF SAND PACK &>lt>nJ.t> ^i/.'fa

DEPTH OF TOP OF SCREENED SECTION

ELEVATION OF TOP OF SCREENED SECTION

ID.. OF SCREENED SECTION

') yktVte

- 3"O(> -SQ ft*t~^

DEPTH OF BOTTOM OF SCREENED SECTION

ELEVATION OF BOTTOM OF SCREENED SECTION

LENGTH OF BLANK SECTION

DEPTH OF PLUG/BOTTOM CAP BELOW GROUND

ELEVATION OF PLUG/BOTTOM CAP

DEPTH OF BOTTOM OF SAND PACK

TYPE OF BACKFILL &~ '2- A?JoraJg 5.'l.r^

IN. I

DEPTH OF HOLE BELOW GROUND SURFACE

ELEVATION OF BOTTOM OF HOLE

I

FIGURE 4
WELL INSTALLATION REPORT

PROJECT

LOCATION

DATE COMPLETED

Virk ou

'/f// t * toft*

WELL NO. 6

PROJECT NO.

PREPARED BY

HEIGHT OF GUrcrAeC CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF SURFACE CASING

HEIGHT OF WELL CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF WELL CASING

ID OF SURFACE CASING AND DIAMETER

TYPE OF GROUT SEAL

DEPTH OF SURFACE CASING BELOW GROUND

ID OF INTERMEDIATE CASING AND DIAMETER

TYPE OF GROUT SEAL At*

TYPE OF GROUT SEAL "Ri*Ai*.tJc

t*

ID OF WELL CASING AND DIAMETER A_

DEPTH OF INTERMEDIATE CASING BELOW GROUND

DIAMETER OF BOREHOLE

DEPTH OF TOP OF BENTONITE SEAL

TYPE OF BENTONfTE SEAL /fr/a

DEPTH OF BOTTOM OF BENTONITE SEAL

DEPTH OF TOP OF SAND PACK

TYPE OFSAND PACkftf 5 /

DEPTH OF TOP OF SCREENED SECTION

ELEVATION OF TOP OF SCREENED SECTION

ID OE SCREENED SECTION

DEPTH OF BOTTOM OF SCREENED SECTION

ELEVATION OF BOTTOM OF SCREENED SECTION

LENGTH OF BLANK SECTION

DEPTH OF PLUG/BOTTOM CAP BELOW GROUND

ELEVATION OF PLUG/BOTTOM CAP

DEPTH OF BOTTOM OF SAND PACK

TYPE OF BACKFILL

e>.

DEPTH OF HOLE BELOW GROUND SURFACE

ELEVATION OF BOTTOM OF HOLE

JU./' ?

FIGURE A
WELL INSTALLATION .REPORT

PROJECT _

LOCATION

DATE COMPLETED \o\Sft\~

oO

CO

WELL NO.

PROJECT NO.

PREPARED BY

HEIGHT OF SUnn'iCE CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF SURFACE CASING

HEIGHT OF WELL CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF WELL CASING

ID OF SURFACE CASING AND ntAUfTFR 16

TYPE OF GROUT SEALffWrs

3. bd* Q.Q.PQ • h

(y 5-^655, )•

-^

DEPTH OF SURFACE CASING BELOW GROUND

ID OF INTERMEDIATE CASING AND DIAMETER

TYPE OF GROUT SEAL

TYPE OF GROUT SEAL ?0r-th*dCpinint

''i'

: 8"

OF WELL CASING AND DIAMETER

fto'J

/f>

£ f07»L $qq .4) -frerrj

DEPTH OF INTERMEDIATE CASING BELOW GROUND

DIAMETER OF BOREHOLE

DEPTH OF TOP OF BENTONITE SEAL

TYPE OF BENTONITE SEAL

CO < fa *

DEPTH OF BOTTOM OF BENTONITE SEAL

DEPTH OF TOP OF SAND PACK

TYPE OF SAND PACK

DEPTH OF TOP OF SCREENED SECTION

ELEVATION OF TOP OF SCREENED SECTION

ID OF SCREENED SECTION & JO

DEPTH OF BOTTOM OF SCREENED SECTION

ELEVATION OF BOTTOM OF SCREENED SECTION

LENGTH OF BLANK SECTION

DEPTH OF PLUG/BOTTOM CAP BELOW GROUND

ELEVATION OF PLUG/BOTTOM CAP

DEPTH OF BOTTOM OF SAND PACK

TYPE OF BACKFILL A/o/£- P/QCy ClbdQ y

DEPTH OF HOLE BELOW GROUND SURFACE

ELEVATION OF BOTTOM OF HOLE

g-oo

FIGURE 4
WELL INSTALLATION REPORT

WELL NO. _

PROJECT NO.

PREPARED BY

- -711

HEIGHT OF SUnrASC CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF SURFACE CASING

HEIGHT OF WELL CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF WELL CASING

ID OF SURFACE CASING AND DIAMETER.

Oltili JLr** •

TYPE OF GROUT SEAL

DEPTH OF SURFACE CASING BELOW GROUND

ID OF INTERMEDIATE CASING AND DIAMETER

11.3

TYPE OF GROUT SEAL

TYPE OF GROUT SEAL

4- ?o l

io£-

ID OF WELL CASINGAND DIAMETER . /O

/

DEPTH OF INTERMEDIATE CASING BELOW GROUND

DIAMETER OF BOREHOLE

DEPTH OF TOP OF BENTONITE SEAL

TYPE OF BENTONrTE SEAL J

VJ7/

V

y

DEPTH OF BOTTOM OF BENTONITE SEAL

DEPTH OF TOP OF SAND PACK

TYPE OF SAND PACK

DEPTH OF TOP OF SCREENED SECTION

ELEVATION OF TOP OF SCREENED SECTION

- ?

ID OF SCREENED SECTION tO -

o

'

to?<f

DEPTH OF BOTTOM OF SCREENED SECTION

ELEVATION OF BOTTOM OF SCREENED SECTION

LENGTH OF BLANK SECTION

DEPTH OF PLUG/BOTTOM CAP BELOW GROUND

ELEVATION OF PLUG/BOTTOM CAP

DEPTH OF BOTTOM OF SAND PACK

TYPE OF BACKFILL ^

1/17. 7V'

DEPTH OF HOLE BELOW GROUND SURFACE

ELEVATION OF BOTTOM OF HOLE

FIGURE 4
PROJECT _

LOCATION ^g-<

DATE COMPLETED

WELL INSTALLATION .REPORT

Y*k WELL NO.

PROJECT NO. ft'5337-705

PREPARED BY

HEIGHT OF S«RF*ee CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF SURFACE CASING

HEIGHT OF WELL CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF WELL CASING

ID OF SURFACE CASING AND niAMFTFR 1C

TYPE OF GROUT SEAL

DEPTH OF SURFACE CASING BELOW GROUND

ID OF INTERMEDIATE CASING AND DIAMETER _

TYPE OF GROUT SEAL

fltA

TYPE OF GROUT SEAL A ""•'*"**

1~t 3T 4 hi) llg kfi4

< *~t f

ID OF WELL CASING AND DIAMETER

" * s.s.

DEPTH OF INTERMEDIATE CASING BELOW GROUND

DIAMETER OF BOREHOLE.

DEPTH OF TOP OF BENTONITE SEAL

TYPE OF BENTONfTE SEAL h ~

DEPTH OF BOTTOM OF BENTONITE SEAL

DEPTH OF TOP OF SAND PACK

TYPE OF SAND PACK

DEPTH OF TOP OF SCREENED SECTION

ELEVATION OF TOP OF SCREENED SECTION

ID OF SCREENED SECTION fl " f 0 Q.oS'

DEPTH OF BOTTOM OF SCREENED SECTION

ELEVATION OF BOTTOM OF SCREENED SECTION

LENGTH OF BLANK SECTION

DEPTH OF PLUG/BOTTOM CAP BELOW GROUND

ELEVATION OF PLUG/BOTTOM CAP

DEPTH OF BOTTOM OF SAND PACK

TYPE OF BACKFILL Co//a/Tg

DEPTH OF HOLE BELOW GROUND SURFACE

ELEVATION OF BOTTOM OF HOLE

3 '

O

FIGURE 4
WELL INSTALLATION REPORT

PROJECT _

LOCATION L<*.

DATE COMPLETED

ftfr WELL NO. .

PROJECT NO. 2A?27 - 7X5"

PREPARED BY

HEIGHT OF 3Hni"AOC CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF SURFACE; CASING

HEIGHT OF WELL CASING ABOVE GROUND SURFACE

ELEVATION OF TOP OF WELL CASING

ID OF, SURFACE CASING AND D1AUFTER lG> "

TYPE OF GROUT ,SEAL ( f° * I

DEPTH OF SURFACE CASING BELOW GROUND

ID OF INTERMEDIATE CASING AND DIAMETER

TYPE OF GROUT SEAL A/A

TYPE OF GROUT SEAL

\jl ffi- ke

Pt,fH<^tf 7^/«

ID OF WELL CASING AND DIAMETER 1*0 •< 2' ff

DEPTH OF INTERMEDIATE CASING BELOW GROUND

DIAMETER OF BOREHOLE

DEPTH OF TOP OF BENTONITE SEAL

TYPE OF BENTONITE SEAL f-fc-te />/*<* Vtr" l,e* J

DEPTH OF BOTTOM OF BENTONITE SEAL

DEPTH OF TOP OF SAND PACK

TYPE OF SAND PACK <irx.t* £<Jto. ^,

DEPTH OF TOP OF SCREENED SECTION

ELEVATION OF TOP OF SCREENED SECTION

ID OF SCREENED SECTION l!l

DEPTH OF BOTTOM OF SCREENED SECTION

ELEVATION OF BOTTOM OF SCREENED SECTION

LENGTH OF BLANK SECTION

DEPTH OF PLUG/BOTTOM CAP BELOW GROUND

ELEVATION OF PLUG/BOTTOM CAP

DEPTH OF BOTTOM OF SAND PACK

TYPE OF BACKFILL £//t^ fl^-t-h V*/3

DEPTH OF HOLE BELOW GROUND SURFACE

ELEVATION OF BOTTOM OF HOLE

FIGURE 4
IIII1IIIIIIIII1III

APPENDIX D

WELL DEVELOPMENT LOGS

22907A-2232''/R2.TS 02-05-92/RPT
MONITORING WELL DEVELOPMENT SUMMARY

TWc* VJo- 2-2-32.7 C -lil^ -Fx.; 7^,^,, /f> Tv,4£

^

Volume of Hater In Voluna

Depth to Wel l Under Static Removed Specific Conductance Temperature

Hel l Date Tine Mater (ft) Conditions (gallons) (gallons) pH (tmhos at 25 'O (*C)

I>O Water

Clarit y

/0/&//9/ iios

1240

M-30

/6£?O

/745

/52-0

iO/3tfr 1 01 25

1^35

/./ ' 5

/405

app rove.

O

/5

'30

40

5o

T5

removed

-7,6-7

52.0 ^.57

-r. 37

z/0

20;

y.^7

7.?

•7.3

6. I

7.25

Z(8 7.70

7.75

7. i. /.4 /

per hour

*

, . _

Iff, (£>

tt f hi a

^J

. 5 — ^

9.47

?.57-

 3^3

i

" «• «r _J f7 ' • «~J<Jc? ^,S^

-, -7 _

/ < ' -

\S- a

Sheet of
MONITORING WELL DEVELOPMENT SUMMARY

Kio ; 2.2^7^1 C - 7 (I Co .

Specific Conductance Temperature <z.rt

(unhos at 25'C) CO

—3-

Ket Date

Volume of Ket«r In Volume

Depth to Wel l Under Static Removed

Tine Water (ft) Conditions (gallons) (gallons)

txD Water

Clarit y

:."

2.20 . .

6

, ,j. /.J

\ I A1450

1545

v\oV

< c V

O

'50

562.

Ls) £> to, 2O SO~7

-75 7.57**

O

A

5/7 ~ -

7,4

7.3

7. 3

7.O

o

o I

•fa.r b i d

— — -V-ujr \o v'A

Sheet of
MONITORING WELL DEVELOPMENT SUMMARY

2.Z-3Z7-

Volume of Water In Volume

Depth to Wel l Under Static Removed

Wel l Date Tine Water (ft) Conditions (gallons) (gallons)

*3uV3 AcrVJV

tft/q/ 5/74, 4_2(4.

/0/2C/1I 1710 — — / i

I^DO — — 12.5 c-t

lOJZljm 0 tOO — -~ '30O !

Specific Conductance

pH (umhos at 25*C)

£} ^ £ V.o"p rrv Q.KA~

?.^ 34 )

^'^^ 24 /

B.05 ZoS

Temperature «.H t>O Water

CO Clarity

<4-, 2. 2-31 &• 1 t> '«

5>^ Z/9 7,4 'frtr'h'J

^3 220 7, 3 -turbCel

^^ ^ CD ^- ^-^ '

ZZl 7.g

'/I Q

elof> n

^.

/4c?5

1545

43

— o

— 2.5

- 45

62.

ved':. ~ SS 4

^,56>

7.50

T,3?

7, 3 /

75V5O Gallons

U

Z&&

5

-3 ,

» *^

5.2 —

£? « /

5,^ —

J

VP»'C.' •/M*'

* )

Sheet of
MONITORING WELL DEVELOPMENT SUMMARY

3 3 3Z~>- 7// C

Specific Conductance Temperature «j.H

Veil Date pH (wihos at 25*C) CO

Voluma of Watar In Voi

Depth to Wel l Under Static Removed

Tine Mater (ft) Conditions (gallons) (gallons)

t>O Hator

Clarit y

/<? yo *.cv,i

//•J o

I* TOO £f««J

O

600

^eo

c.-Ti

•a ^7

- i

*-/

7 •?

7-7

7.35 Tuft,,. s

5*0

7. 70 7.

7-

Sheet / of
MONITORING WELL DEVELOPMENT SUMMARY

- 7/if .

Well Date

Volume of Ketar In Volume

Depth to Well Under Static Removed

Tine Water (ft) Conditions (gallons) (gallons)

Specific Conductance Temperature «.H

pH <w«hos at 25*C) CO

t>O Water

Clarity

lo'- 10

./"*M

t'/31/Cf, yc Ar

fti

«-.$• 7.? a

til 23V

? 55 237

7, <j ~

y?Z" flietur UifA *»«U' r1^ V

Sheet .3 ot"
MONITORING WELL DEVELOPMENT SUMMARY

T

7 - 7/'£

Wel l Dote

Volume of Water In Volume

Depth to Well Under Static Removed

Tine Water (ft) Conditions (gallons) (gallons)

Specific Conductance T«nparetur« «.H

pH (unttos at 25*C) CO

I>O Water

Clarity

7? X

n : oo

/a \*o

I J : fo

i 7 • "/.*• O

t«.,3 t,..,

C «•« n i

10 r

. y i^ii^ G

o

/ o

/ 5

? 3

C 5"

7>*

.r ••

7 <Jc?

7.72

7. A/

7.V2

7.5'?

?. V?

V" 2 2.

77 7

-T32

^-5

to. t

,o- 3

/o-s

f /. X

/c; 3

;o. /

/o. 3

Sheet / of
MONITORING WELL DEVELOPMENT SUMMARY

7- 7/l(, &

Aff-'-'Y ->

Volume of Water In Volume

Depth to Wel l Under Static Removed Specific Conductance Tenperature «.ft

Wel l Date Tine Water (ft) Conditions (gallons) (gallons) pH (wibos at 25*C) CO

/?(/-05* fi>4(fer Otvc(o/>i wj- ~ l^cf 77~i

'

ivffn/tf i?:^O 7 f£.} fO 1 '

XV*

i^iUO Qje<ji«} ^

f<i.-Lff (^ "7. fi 5" 2 3 ~(C)-0

t*;oO (<tt*f) IV 7-fr/ S'/S' 1-7

iQ/w/if o9:'jo (3l~^& ot-cc) 3 O ?.<•<» 5^<J 9. ' •

t>O Water

Clarity

'i'-l?

/fr:/J

7 1

i.JZ

Sheet o of 2
MONITORING WELL DEVELOPMENT SUMMARY

2-2.3Z.7C. -1 I U.

Wei 1 Date

Volume Of Hater In Volume

Depth to Wel l Under Static Removed

Time Water (ft) Conditions (gallons) (gallons)

Specific Conductance Temperature

pH (tmhos at 25'C) CO

I>O Water

Clarity

10/24 fit 16,00 221.

1030 —

12.00 —

/35c; —

/OOCL\ o

£

50

10

30

<oo

I O

. -77

7, 12-77

5,2>

s.e

s.?

(o.O

5,7

u

a

Sheet of
IIIIIIIIIIIIIIIIIII

APPENDIX E

SURVEYING DATA

02-28-92/RPT
^ _H fi^c* T>eeP M»«niMA* Weu*

Dat« JAU. 2O. I«W2. Job No.: SJ-111

Map Projection: 1927 State Plane: Lambert Confromal Confc

Projection Zone Colorado Central

Identification

and Point

Number

BBVU-I

peepvuecL.

^^^4^%O

TjtT^'jl*"*^

•BBVU-4

•BBUJ-S

•BBW-7

Date

of

Location

t/7/12.

1/7/12.

1/13/12.

•AM

,/*/*

^.

State Plane

Northing

513,778.37

sn;7i4.si

S,7ySS«,^

511,866. ZO

518,68^.4^

511,777.70

State Plane

Easting

|/788,3«.ai

W"-»

,,TM,»7.0«

WW.S,

»"M»-»

1,782,327.15

Scale Factor. O.11113884

Sea Level Factor O.T11'474OG>

Combined Fac

Reciprocal Fa

Elevation

(Top of External

Well Housing)

iu*i-<n

,0,^..^

».***

1 1,545. IG

M,J10.86

10,445.51

rtor: 0.11141213

ctor 1. 0005874-1

Elevation

[Top of

Well Casing)

s

1^220.43

***»

nnt.ii

(1,544.11

»^a55

10,445.06

Uevatfon

Ground at

Norm Side

(s)

1,220.15

10,714.41

M, 235. 11

II,S43.85

.wu

ft*«77

Data File

File and

Fieldbook

•BK.20/

/P.35

^^s

*OI»3

8K'?B43

SK.20/

/R3S

^0113

Rl/ toX 9^» » *y ^^

ttt^^OX

• •Z/

f/^fl

'i^Lr' '^Zii "J tib Consultants, Ltd.

^~ ^^ 1 BOOn Cn.<ti \~~rt-** D«^

Engtewood. Colorado 80112

(303)690-7700

Project

Basemap

Sheet

1

,

5

10

5

=|

Notes

l/<S/«?i & 1/7/12.

Locanow BV S?S. I/6/12.

8» 1/7/12,

*^loo &> * 2O3

LocA-nowBY &HS. 1/6/12.

^"(oo ?/ ""^2.03

Loc/^noAj FI^OM Co*jn?D(_ nwvn

*2O8 8f*2C^
\m

i

HE Consultants, Ltd.

PROJECT.

SUBJECT.

Deep W6LLS

CLIENT.

. BY

CHK.

. JOB NO. O/~//T

. DATE.

OF

/ /

SHEET NO..

OF

CM TfPlCftL VvJELJL S\TE

TOP OF WELLftoUSlMG CftP

Top OF

WORTH SIDE OF VAJ6LL