Attachment_23_Test_Pits_at_LMDT_WTP_Leadville__CO_Travel_Report.pdf

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Bureau of Reclamation Great Plains Region

Geology and Exploration Services Group

July 2019

TRAVEL REPORT

To: Cody Clark, Regional Geologist, Great Plains Region

From: Seth Joramo, Geologist

Subject: 2018 Test Pits at Leadville Mine Drainage Tunnel - Water Treatment Plant

Leadville, Colorado

1. Travelers: Seth Joramo, Geologist and Chance Reynolds, Operator; Great

Plains Regional Office, Geology and Exploration Services (GP-2300)

2. Travel Period: November 5, 2018 through November 8, 2018

3. Places or Offices Visited: Leadville Mine Drainage Tunnel Water Treatment Plant, Colorado

4. Purpose of Trip:

Located approximately 1.5 miles north of the town of Leadville, CO is the Leadville Mine Drainage Tunnel (LMDT) - Water Treatment Plant (WTP). Owned and operated by the Bureau of Reclamation, the facility is used to treat acid mine drainage water draining from local mines through the LMDT. The treated water is discharged into the nearby East Fork of the Arkansas river. There is a long history of mining activities in the Leadville area. The LMDT was acquired from the former U.S. Bureau of Mines in December of 1959 to potentially use as a water conveyance feature for the Fryingpan- Arkansas Project. The current Water Treatment Plant has been in operation since 1992.

The Field Exploration Request (FER) called for three test pits. Two test pits, TP18-1 and TP18-2, are located outside and east of the existing perimeter fence (FER Figure #2). TP18-1 and TP18-2 will be used to determine foundation conditions for the pad cut back and stem wall. TP18-3 is located just east of the existing water treatment plant in the sludge box storage yard (FER Figure #2). TP18-3 will be used to determine foundation conditions of the proposed water treatment plant. Materials were collected from each test pit for lab testing at the TSC Concrete, Geotechnical and Structural Laboratory.

The intent of these test pits is to develop geologic design data by characterizing the subsurface geologic conditions, collecting samples, and determining the physical properties of foundation soils for the proposed Water Treatment Plant. Data will also be used to develop an understanding of in-situ soil strength to evaluate slope stability.

5. Synopsis of Trip:

On November 5th, Chance Reynolds and Seth Joramo traveled to Leadville, Colorado.

Tuesday morning, Chance Reynolds and Seth Joramo rented a bobcat 337D mini excavator and worked with Colorado One-Call to locate any utilities in the vicinity of the proposed test pits. The afternoon was spent excavating TP18-1. Wednesday, TP18- 2 and TP18-3 were excavated and samples were delivered to the TSC Concrete, Geotechnical, and Structural Laboratory. On November 8th, personnel traveled back to Billings, MT.

6. Site Geology:

Historical mining operations along with recent development may have altered the landscape and locally disturbed the geologic units to some degree near the WTP. The current and proposed replacement water treatment plant is situated within Outwash Gravel of Pinedale Glaciation (Qgp). The East Fork of the Arkansas River has dissected down through the glacial deposits followed by deposition of Quaternary Alluvium (Qal) approximately 160 feet north of the plant [1].

Quaternary Alluvium (Qal) is predominantly post-glacial flood plain and terrace deposits. Locally, glacial kettles and other glacial depressions have accumulated alluvial silts and clays. Typically, Qal is found less than 5 meters above active stream channels [1]. An ephemeral stream most likely deposited the alluvium that was only encountered in test pit TP18-2.

Outwash Gravel of Pinedale Glaciation (Qgp) consists of gravel, cobbles, and boulders in a silty sand matrix. Sand lenses and sandy gravel are interbedded within this unit.

Outwash terrace treads of this unit range from 3 to 10 meters above active stream channels. The outwash gravel is primarily reworked till [1]. Glacial outwash was encountered in all three test pits.

7. Report of Findings:

TP18-1

TP18-1 was located approximately 30 feet east of the northeast corner of the yard fence and east of the current water treatment plant. Excavation of the test pit proceeded quickly and easily. The operator excavated the test pit with a Bobcat 337D mini excavator equipped with a 24-inch bucket and teeth. The test pit largely stayed open, only caving in at the depth of termination. The test pit was terminated at 10.0 feet, when the limits of the equipment were reached (Photograph #2).

The visually classified Poorly-Graded Sand with Silt and Gravel (SP-SM)g encountered in test pit was homogenous, light brown, firm, and moist. Roots and other organics were present from 0.0 to 3.0 feet. Hard, 3-inch to 12-inch subrounded cobbles were encountered throughout the test pit and made up approximately 25% of the sample by volume. Maximum size recovered from the test pit was 1.0’ x 0.9’ x 0.8’. The material is interpreted to be Outwash Gravel of Pinedale Glaciation (Qgp) (Appendix B).

Since the maximum grain size varied from cobbles to small boulders, a large sample volume was needed for representative soil samples [3]. One supersack (≈ 500 lb) sample was collected in the test pit for shear box and standard physical properties testing (Photograph #1). A large amount of 3-inch plus cobbles and boulders were removed at the request of the TSC Concrete, Geotechnical and Structural Laboratory (Photograph #1). The removed cobbles and boulders were used to estimate the percentage by volume of 3-inch plus material. Upon completion, the cobbles and boulders were placed back into the test pit.

Lab Results: 0.0 to 10.0 feet. – Sample no. 95 – fines=7.6%, sand=46.4%, gravel=46.0%, LL=NP, PI=NP, Laboratory Classification is: (SP-SM)g [4].

Direct Shear Test: 0.0 to 10.0 feet. – Sample no. 95 – Compacted Dry Unit Weight = 130.2 lbf/ft2; Peak Drained Linear Friction Angle = 44.4o; Actual Normal Stress at Failure (lbf/ft2) - Spec1 = 1115, Spec2 = 2156, Spec3 = 4181; Peak Shear Stress on Failure Plane at Failure (lbf/ft2) – Spec1 = 1080, Spec2 = 1820, Spec3 = 4250 [4].

Two plastic-lined five-gallon buckets were collected at 5.0 feet and two at 10.0 feet for standard physical properties testing. Two 1-gallon double bagged samples were collected at 5.0 feet and two at 10.0 feet to determine moisture content.

LAB TEST DATA: 0.0 to 5.0 feet – Sample no. 96 – fines=5.5%, sand=46.7%, gravel=47.8%, LL=NP, PI=NP, MC=5.7%, Laboratory Classification is: (GP-GM)s [4].

LAB TEST DATA: 5.0 to 10.0 feet – Sample no. 97 – fines=7.3%, sand=45.3%, gravel=47.4%, LL=NA, PI=NA, MC=3.0%, Laboratory Classification is: (GP-GM)s [4].

A corrosivity sample was collected at 10.0 feet to represent foundation and retaining wall corrosivity potential. It included two half-filled 1-gallon Ziploc bags placed together inside another 1-gallon Ziploc bag. The samples were then placed inside a cooler packed with snow from the site. Resistivity, Chloride Concentration, Sulfate Concentration, and pH testing were performed on the sample. To minimize the action of sulfate reducing bacteria for sulfate testing, the sample needed to remain cool at approximately 40 degrees.

The results of the corrosivity test are: Resistivity (Ω-cm) = Moderate, pH = Neutral, Chlorides (mg/L) = Low, and Sulfates (mg/L) = Low [2].

TP18-2:

Test pit was located approximately 140 feet southeast from the northeast corner of the yard fence and east of the current water treatment plant. Excavation of the test pit proceeded quickly and easily. The operator excavated the test pit with a Bobcat 337D mini excavator equipped with a 24-inch bucket and teeth. The test pit largely stayed open, only caving in at the depth of termination. The test pit was terminated at 10.0 feet, when the limits of the equipment were reached (Photograph #4).

The visually classified Clayey Sand (SC) encountered from 0.0 to 3.0 feet in the test pit was homogenous, gray to dark brown, firm, and moist. Roots and other organics were present throughout to a depth of 3.0 feet. The material is interpreted to be Quaternary Alluvium (Qal) (Appendix B).

The visually classified Silty Sand with Gravel (SM)g encountered from 3.0 to 10.0 feet, in the test pit was homogenous, light brown, firm, and moist. Hard, 3-inch to 12-inch subrounded cobbles were encountered throughout the test pit and made up approximately 20% of the sample by volume. Maximum size recovered from the test pit was 1.2’ x 0.8’ x 0.4’. The material is interpreted to be Outwash Gravel of Pinedale Glaciation (Qgp) (Appendix B).

Since the maximum grain size varied from cobbles to small boulders, a large sample volume was needed for representative soil samples [3]. One supersack (≈ 500 lb) sample was collected in the test pit for shear box and standard physical properties testing. A large amount of 3-inch plus cobbles and boulders were removed at the request of the TSC Concrete, Geotechnical and Structural Laboratory (Photograph #1).

The removed cobbles and boulders were used to estimate the percentage by volume of 3-inch plus material. Upon completion, the cobbles and boulders were placed back into the test pit.

LAB TEST DATA: 3.0 to 10.0 feet – Sample no. 99 – fines=12.8%, sand=46.1%, gravel=41.1%, LL=NP, PI=NP, Laboratory Classification is: (SM)g [4].

DIRECT SHEAR TEST: 3.0 to 10.0 feet – Sample no. 99 – Compacted Dry Unit Weight = 124.8 lbf/ft2; Peak Drained Linear Friction Angle = 38.2o; Actual Normal Stress at Failure (lbf/ft2) - Spec1 = 1000, Spec2 = 1967, Spec3 = 3968; Peak Shear Stress on Failure Plane at Failure (lbf/ft2) – Spec1 = 710, Spec2 = 1380, Spec3 = 3220 [4].

Two plastic-lined five-gallon buckets were collected at each of the depths of 3.0 feet,

5.0 feet and 10.0 feet for standard physical properties testing. Two 1-gallon double bagged samples were collected at each depth of 3.0 feet, 5.0 feet and10.0 feet to determine moisture content.

LAB TEST DATA: 0.0 to 3.0 feet – Sample no. 100 – fines=35.7%, sand=36.9%, gravel=27.4, LL=31, PI=15, MC=8.8%, Laboratory Classification is: (SC)g [4].

LAB TEST DATA: 3.0 to 5.0 feet – Sample no. 101 – fines=24.3%, sand=56.3%, gravel=19.4%, LL=NP, PI=NP, MC=9.3%, Laboratory Classification is: (SM)g [4].

LAB TEST DATA: 5.0 to 10.0 feet – Sample no. 102 – fines=5.8%, sand=43.7%, gravel=50.5%, LL=NP, PI=NP, MC=4.5%, Laboratory Classification is: (GP-GM)s [4].

A corrosivity sample was collected at 10.0 feet to represent foundation and retaining wall corrosivity potential. It included two half-filled 1-gallon Ziploc bags placed together inside another 1-gallon Ziploc bag. The samples were then placed inside a cooler packed with snow from the site. Resistivity, Chloride Concentration, Sulfate Concentration, and pH testing were performed on the sample. To minimize the action of sulfate reducing bacteria for sulfate testing, the sample needed to remain cool at approximately 40 degrees.

The results of the corrosivity test are: Resistivity (Ω-cm) = Moderate, pH = Neutral, Chlorides (mg/L) = Low, and Sulfates (mg/L) = Low [2].

TP18-3:

The first test pit (TP18-3) was conducted at the proposed site for TP-18-3 (FER Figure 2 in Appendix #). Excavation of the test pit proceeded quickly and easily. The operator excavated the test pit with a Bobcat 337D mini excavator equipped with a 24-inch bucket and teeth (Photograph #5). The test pit largely stayed open, only caving in at the depth of termination. The test pit was terminated at 10.0 feet, when the limits of the equipment were reached (photograph #6).

The visually classified Poorly-Graded Sand with Silt and Gravel (SP-SM)g encountered in test pit was homogenous, light brown, firm, and moist. Hard, 3-inch to 5-inch subrounded cobbles were encountered throughout the test pit and made up approximately 5% of the sample by volume. By volume, a trace of hard, 5-inch to 12-inch, subrounded cobbles, with a maximum size of 0.8’ x 0.8’ x 0.5’ was recovered from the test pit. The material is interpreted to be geologic unit Outwash Gravel of Pinedale Glaciation (Qgp) (Appendix B).

Two plastic lined five-gallon buckets were collected at 5.0 feet and two at 10.0 feet for standard physical properties testing. Two 1-gallon double bagged samples were collected at 5.0 feet and two at 10.0 feet to determine moisture content.

LAB TEST DATA: 0.0 to 5.0 feet – Sample no. 104 – fines=21.1%, sand=58.1%, gravel=20.7%, LL=NP, PI=NP, MC=13.7%, Laboratory Classification is: (SM)g [4].

LAB TEST DATA: 5.0 to 10.0 feet – Sample no. 105 – fines=17.7%, sand=57.0%, gravel=25.3%, LL=NP, PI=NP, MC=7.5%, Laboratory Classification is: (SM)g [4].

8. Summary:

The location of the three test pits are shown in Figure 2 of the FER. The excavation of the test pits was in the same approximate locations as in the FER. Coordinates and elevation were collected using a Delorm Earthmate PN-40 handheld GPS unit with DATUM WGS

84. The locations were also marked with standard t-posts to aid in surveying.

The in-situ subsurface appears to be undisturbed glacial outwash in the areas the test pits were excavated. However, historical mining or development may have led to disturbance that cannot be seen or predicted in these areas. Glacial Outwash is expected to extend across the proposed construction site. The two USCS visual classifications of the glacial outwash units in the three test pits include; Poorly-Graded Sand with Gravel and Silty Sand with Gravel with approximately 50% to 60% fine to coarse sand. 3-inch to 12-inch cobbles make up 5% to 25% of the samples, by volume. In TP-18-2 there is an upper layer of alluvium with a USCS visual classification of Clayey Sand that includes approximately 60% fine to coarse sand. Logs with test pit sketches are included in Appendix B.

The lab classification for the super sack sample taken in TP18-1 was Poorly-Graded Sand with Silt and Gravel (SP-SM)g. The bucket samples were lab classified as Poorly-Graded Gravel with Silt and Sand (GP-GM)s. Sample size was too small in the bucket sample to be representative of the corresponding zone within the test pit.

The lab classification for the super sack sample taken in TP18-2 was Silty Sand with Gravel (SP-SM)g. The bucket samples were lab classified as Sandy Clay with Gravel (SC)g, Silty Sand with Gravel (SM)g, and Poorly-Graded Gravel with Silt and Sand (GP-GM)s. Sample size was too small in the bucket sample to be representative of the corresponding zone within the test pit.

The bucket samples collected in TP18-3 were lab classified as Silty Sand with Gravel (SM)g. Sample size was too small in the bucket sampled to be representative of the corresponding zone within the test pit.

TP18-1 direct shear testing on the Poorly-Graded Sand with Silt and Gravel (SP-SM)g collected from a depth of 0.0 to 10.0 feet showed an effective stress peak friction angle equal to 44.4o and a post-post peak effective stress friction angle of 32.3o. The effective stress cohesion was assumed to be zero for remolded, free draining, coarse grained soil.

Well-defined peak drained shear stresses for this sample were fully developed between 2.8% and 3.6% relative horizontal strain. Specimens exhibited only minor volume change during shear, with two specimens contracting with less than 0.3% axial strain at failure, and one specimen dilating with less than -0.2% axial strain at failure. [4]

TP18-2 direct shear testing on the Silty Sand with gravel (SM)g collected from a depth of

3.0 to 10.0 feet showed an effective stress peak friction angle equal to 38.2o and a post-peak effective stress friction angle of 33.7o. The effective stress cohesion was assumed to be zero for remolded, free-draining, coarse-grained soil. Poorly-defined, peak drain shear stresses for this sample were developed between 4.2% and 5.5% relative horizontal strain. All specimens exhibited a small amount of dilative behavior with less than -0.9% axial strain at failure. [4]

Lab results of the corrosivity testing indicates there is a low probability of adverse reaction with buried structures. [2]

References:

[1] Ruleman, C.A., Brant, T.R., Caffee, M.W., and Goehring, B.M., 2018, Geologic Map of the Leadville North 7.5’ Quadrangle, Eagle and Lake Counties, Colorado: The Geological Survey, Map SIM-3400, one Adobe Acrobat (PDF) file, scale 1:24,000, available on https://ngmdb.usgs.gov/Prodesc/proddesc_107166.htm.

[2] Bureau of Reclamation, 2019. Corrosivity Testing – Leadville Mine Drainage Tunnel Water Treatment Plant, Referral Number: 8540-2019-06, Great Plains region, Colorado. U.S.

Department of the Interior, Technical Service Center, Denver, Colorado.

[3] ASTM D7928-17, Standard Test Method for Particle-Size Distribution (Gradation) of Fine- Grained Soils Using the Sedimentation (Hydrometer) Analysis, ASTM International, West Conshohocken, PA.

[4] Bureau of Reclamation, 2019. Geotechnical Laboratory testing Results for Leadville Mine Drainage Tunnel Water Treatment Plant Foundation Material, Technical Memorandum Number:

8530-2019-25, Great Plains Region, Colorado. U.S. Department of the Interior, Technical Service Center, Denver, Colorado.

https://ngmdb.usgs.gov/Prodesc/proddesc_107166.htm

Appendix

Appendix A – Photographs

Appendix B - Geologic Logs

Appendix C – Corrosivity Testing – Leadville Mine Drainage

Tunnel Water Treatment Plant

Appendix D – Geotechnical Laboratory testing Results for

Leadville Mine Drainage Tunnel Water Treatment Plant

Foundation Material

Appendix E - FER (Field Exploration Request)

Appendix A

Photographs

Photograph 1 - Leadville Mine Drainage Tunnel Water Treatment Plant – Colorado This photograph shows 2 bucket and 1 super sack samples from test pit TP18-1. On the right side of the photograph is the 3-inch plus material sorted on the blue tarp.

Bureau of Reclamation Photograph by Seth Joramo on 11-6-2018

Photograph 2- Leadville Mine Drainage Tunnel Water Treatment Plant – Colorado This photograph shows test pit TP18-1. The Poorly-Graded Sand with Silt and Gravel was easily excavated to a total depth of 10.0 feet.

Bureau of Reclamation Photograph by Seth Joramo on 11-6-2018

Photograph 3- Leadville Mine Drainage Tunnel Water Treatment Plant – Colorado This photograph shows the 1 super sack sample from test pit TP18-2. On the right side of the photograph is the 3-inch plus material sorted on the blue tarp.

Bureau of Reclamation Photograph by Seth Joramo on 11-7-2018

Photograph 4 - Leadville Mine Drainage Tunnel Water Treatment Plant – Colorado This photograph shows test pit TP18-2. Above the red line shows the Clayey Sand to a depth of 3.0 feet. Below the red line shows the Silty Sand with Gravel from 3.0 to a total depth of 10.0 feet. The test pit was easily excavated to a total depth of 10.0 feet.

Photograph 5 - Leadville Mine Drainage Tunnel Water Treatment Plant – Colorado This photograph shows test pit TP18-3. A super sack sample was not required in this test pit. 3-inch plus material was estimated at 5 percent.

Photograph 6 - Leadville Mine Drainage Tunnel Water Treatment Plant – Colorado This photograph shows test pit TP18-3. The Poorly-Graded Sand with Silt and Gravel was easily excavated to a total depth of 10.0 feet.

Appendix B

Geologic Logs

7-1336-A (1-86) Bureau of Reclamation LOG OF TEST PIT OR AUGER HOLE HOLE NO: TP18-1

SHEET 1 OF 1

FEATURE: Leadville Water Treatment Plant PROJECT: Leadville Mine Drainage Tunnel

GROUND ELEVATION: ≈ 9998’

COORDINATES: N 390 16.4643’ W 1060 17.2428’ DATUM: WGS84 METHOD OF EXPLORATION: Bobcat 337D APPROXIMATE DIMENSIONS: 3.0’x 15.0’x 10.0’ deep LOGGED BY: S. Joramo DEPTH TO WATER: Not Encountered DATE(S) LOGGED: 11/16/2018

CLASSIFICATION

GROUP

SYMBOL

(describe sample taken)

CLASSIFICATION AND DESCRIPTION OF MATERIAL

SEE USBR 5000, 5005

% PLUS 3 inch

(BY VOLUME)

3 – inch

5 – inch

PLUS

inch

(SP-SM)g (visual)

One Supersack

0.0 – 10.0 ft.

(SP-SM)g (lab class.)

2 - Buckets

0.0 – 5.0 ft.

(GP-GM)s

5.0 – 10.0 ft.

(GP-GM)s

10.0 ft. 2, 0.5-gal. Ziploc bags (Corrosivity)

10.0 ft.

0.0 to 10.0 ft. POORLY-GRADED SAND WITH SILT AND GRAVEL (SP-SM)g:

Approximately 50% fine to coarse, predominantly medium, hard, subrounded sand;

approximately 40% fine to coarse, hard, subrounded to subangular gravel;

approximately 10% nonplastic fines, rapid dilatancy, low dry strength. No reaction with HCl.

TOTAL SAMPLE (BY VOLUME): Approximately 20% 3 to 5 inch hard, subrounded cobbles; approximately 5% 5 to 12 inch, hard, subrounded cobbles;

approximately a trace of 12 inch plus, hard, subrounded boulders; remainder minus 3 inch; Maximum size recovered = 1.0’ x 0.9’ x 0.8’.

IN-PLACE CONDITION: Homogenous, organic matter and roots 0.0 to 3.0 feet, firm, dry to moist, light brown.

LAB TEST DATA: 0.0’ to 10.0’ – Sample no. 95 – fines=7.6%, sand=46.4%, gravel=46.0%, LL=NP, PI=NP, Laboratory Classification is: (SP-SM)g

DIRECT SHEAR TEST: 0.0’ to 10.0’ – Sample no. 95 – Compacted Dry Unit Weight = 130.2 lbf/ft2; Peak Drained Linear Friction Angle = 44.4o; Actual Normal Stress at Failure (lbf/ft2) - Spec1 = 1115, Spec2 = 2156, Spec3 = 4181; Peak Shear Stress on Failure Plane at Failure (lbf/ft2) – Spec1 = 1080, Spec2 = 1820, Spec3 =

LAB TEST DATA: 0.0’ to 5.0’ – Sample no. 96 – fines=5.5%, sand=46.7%, gravel=47.8%, LL=NP, PI=NP, MC=5.7%, Laboratory Classification is: (GP-GM)s

LAB TEST DATA: 5.0’ to 10.0’ – Sample no. 97 – fines=7.3%, sand=45.3%, gravel=47.4%, LL=NA, PI=NA, MC=3.0%, Laboratory Classification is: (GP-GM)s

Corrosivity Testing: Resistivity (Ω-cm) = Moderate, pH = Neutral, Chlorides (mg/L) = Low, Sulfates (mg/L) = Low.

GEOLOGIC INTERPRETATION: Outwash Gravel of Pinedale Glaciation (Qgp)

20 5 T

REMARKS: Test pit was performed to determine foundation conditions for the pad cut back and stem wall for the Water Treatment Plant replacement. A majority 3-inch plus material was removed onsite from the sample Before sending the sample to the lab. Test pit was terminated at 10.0 ft upon reaching limit of mini excavator.

LOCATION: Approximately 45 feet east from the northeast corner of the yard fence. East of the existing Water Treatment Plant.

S. Joramo 11-6-2018 Leadville Mine Drainage Tunnel

Water Treatment Plant

Test Pit TP18-1

Plan

45.0'

15.0'

3.0'

N

East Fence

10.0'

Profile

(SP-SM)g

Scale 1" = 5'

1 1

North East Corner of the Yard Fence

Bureau of Reclamation LOG OF TEST PIT OR AUGER HOLE HOLE NO: TP18-2

SHEET 1 OF 1

FEATURE: Leadville Water Treatment Plant PROJECT: Leadville Mine Drainage Tunnel

GROUND ELEVATION: ≈9,998’

COORDINATES: N 390 16.4406’ W 1060 17.2486’ DATUM: WGS84 METHOD OF EXPLORATION: Bobcat 337D APPROXIMATE DIMENSIONS: 3’x 15’x 10’ deep LOGGED BY: S. Joramo DEPTH TO WATER: Not Encountered DATE(S) LOGGED: 11/17/2018

CLASSIFICATION

GROUP

SYMBOL

(describe sample taken)

CLASSIFICATION AND DESCRIPTION OF MATERIAL

SEE USBR 5000, 5005

% PLUS 3 inch

(BY VOLUME)

3 – inch

5 – inch

PLUS

inch

SC

(visual)

0.0 – 3.0 ft.

(SC)g

3.0 ft.

0.0 to 3.0 ft. – CLAYEY SAND (SC): Approximately 60% fine to coarse, predominantly medium, hard, subrounded sand; approximately 30% medium plasticity fines, high toughness, slow dilatancy, high dry strength; approximately 10% fine to coarse, hard, subrounded gravel. No reaction with HCl.

IN-PLACE CONDITION: Homogenous; organic matter and roots throughout; firm;

gray and dark brown.

LAB TEST DATA: 0.0’ to 3.0’ – Sample no. 100 – fines=35.7%, sand=36.9%, gravel=27.4, LL=31, PI=15, MC=8.8%, Laboratory Classification is: (SC)g

GEOLOGIC INTERPRETATION: Quaternary Alluvium (Qal)

(SM)g (visual)

One Supersack

3.0 – 10.0 ft.

3.0 – 5.0 ft.

(GP-GM)s (lab class.)

10.0 ft. 2, 0.5-gal. Ziploc bags (Corrosivity)

10.0 ft.

3.0 to 10.0 ft. SILTY SAND WITH GRAVEL (SM)g: Approximately 60% fine to coarse, predominantly medium, hard, subrounded sand; approximately 20% fine to coarse, hard, subrounded to subangular, gravel; approximately 20% nonplastic fines, rapid dilatancy, low dry strength. No reaction with HCl.

TOTAL SAMPLE (BY VOLUME): Approximately 15% 3 to 5 inch hard, rounded to subrounded cobbles; approximately 3% 5 to 12 inch, hard, subrounded cobbles;

approximately 2% 12 inch plus, hard, subrounded boulders; remainder minus 3 inch;

Maximum size recovered = 1.2’ x 0.8’ x 0.4’.

IN-PLACE CONDITION: Homogenous, firm, moist, light brown.

LAB TEST DATA: 3.0’ to 10.0’ – Sample no. 99 – fines=12.8%, sand=46.1%, gravel=41.1%, LL=NP, PI=NP, Laboratory Classification is: (SM)g

DIRECT SHEAR TEST: 3.0’ to 10.0’ – Sample no. 99 – Compacted Dry Unit Weight = 124.8 lbf/ft2; Peak Drained Linear Friction Angle = 38.2o; Actual Normal Stress at Failure (lbf/ft2) - Spec1 = 1000, Spec2 = 1967, Spec3 = 3968; Peak Shear Stress on Failure Plane at Failure (lbf/ft2) – Spec1 = 710, Spec2 = 1380, Spec3 =

LAB TEST DATA: 3.0’ to 5.0’ – Sample no. 101 – fines=24.3%, sand=56.3%, gravel=19.4%, LL=NP, PI=NP, MC=9.3%, Laboratory Classification is: (SM)g

LAB TEST DATA: 5.0’ to 10.0’ – Sample no. 102 – fines=5.8%, sand=43.7%, gravel=50.5%, LL=NP, PI=NP, MC=4.5%, Laboratory Classification is: (GP-GM)s Corrosivity Testing: Resistivity (Ω-cm) = Moderate, pH = Neutral, Chlorides (mg/L) = Low, Sulfates (mg/L) = Low.

GEOLOGIC INTERPRETATION: Outwash Gravel of Pinedale Glaciation (Qgp)

15 3 2

REMARKS: Test pit was performed to determine foundation conditions for the pad cut back and stem wall for the Water Treatment Plant replacement. A majority 3-inch plus material was removed onsite from the sample Before sending the sample to the lab. Test pit was terminated at 10.0 ft upon reaching limit of mini excavator.

LOCATION: Approximately 140 feet southeast from the northeast corner of the yard fence.

S. Joramo 11-7-2018 Leadville Mine Drainage Tunnel

Test Pit TP18-2

15.0'

3.0 '

N

20.0'

East Fence

10.0'

Plan

Profile

SC

(SM)g

1 1

Scale 1" = 5'

Bureau of Reclamation LOG OF TEST PIT OR AUGER HOLE HOLE NO: TP18-3

SHEET 1 OF 1

FEATURE: Leadville Water Treatment Plant PROJECT: Leadville Mine Drainage Tunnel

GROUND ELEVATION: ≈ 9982’

COORDINATES: N 390 16.4428’ W 1060 17.2658’ DATUM: WGS84 METHOD OF EXPLORATION: Bobcat 337D APPROXIMATE DIMENSIONS: 3’x 12.2’x 10’ deep LOGGED BY: S. Joramo DEPTH TO WATER: Not Encountered DATE(S) LOGGED: 11/17/2018

CLASSIFICATION

GROUP

SYMBOL

(describe sample taken)

CLASSIFICATION AND DESCRIPTION OF MATERIAL

SEE USBR 5000, 5005

% PLUS 3 inch

(BY VOLUME)

3 – inch

5 – inch

PLUS

inch

(SP-SM)g (visual)

2 - Buckets

0.0 – 5.0 ft.

10.0 ft.

0.0 to 10.0 ft. POORLY-GRADED SAND WITH SILT AND GRAVEL (SP-SM)g:

Approximately 60% fine to coarse, predominantly medium, hard, subrounded sand;

approximately 30% fine to coarse, hard, subrounded to subangular gravel;

approximately 10% nonplastic fines, rapid dilatancy, low dry strength. No reaction with HCl.

TOTAL SAMPLE (BY VOLUME): Approximately 5% 3 to 5 inch hard, rounded to subrounded cobbles; approximately a trace of 5 to 12 inch, hard, subrounded cobbles; remainder is minus 3 inch; Maximum size recovered = 0.8’ x 0.8’ x 0.5’.

IN-PLACE CONDITION: Homogenous, firm, moist, light brown.

LAB TEST DATA: 0.0’ to 5.0’ – Sample no. 104 – fines=21.1%, sand=58.1%, gravel=20.7%, LL=NP, PI=NP, MC=13.7%, Laboratory Classification is: (SM)g

LAB TEST DATA: 5.0’ to 10.0’ – Sample no. 105 – fines=17.7%, sand=57.0%, gravel=25.3%, LL=NP, PI=NP, MC=7.5%, Laboratory Classification is: (SM)g

GEOLOGIC INTERPRETATION: Outwash Gravel of Pinedale Glaciation (Qgp)

5 T

REMARKS: Test pit was performed to determine foundation condition beneath the Water Treatment Plant Replacement. Test pit was terminated at 10.0 ft upon reaching limit of backhoe.

LOCATION: Approximately 65 feet east of the existing Water Treatment Plant building half way between the north and south perimeter fence.

S. Joramo 11-7-2018 Leadville Mine Drainage Tunnel

Test Pit TP18-3

140.0'

15.0'

3.0' N

Plan

Profile

(SP-SM)g

10.0'

East Fence

Scale 1" = 5'

1 1

Northeast Corner of Yard Fence

Appendix C

Corrosivity Testing – Leadville Mine Drainage Tunnel Water

Treatment Plant

United States Department of the Interior

BUREAU OF RECLAMATION

PO Box 25007

Denver, CO 80225-0007

86-68540 January 30, 2019 2.2.4.21

VIA ELECTRONIC MAIL ONLY

MEMORANDUM

To: Reclamation Technical Service Center, Civil Engineering Services Division, Water Treatment Group, Denver, CO Attention: Katie Guerra (86-68190)

From: Jessica Torrey, Materials and Corrosion Laboratory (MCL), 86-68540

Subject: Corrosivity Testing – Leadville Mine Drainage Tunnel Water Treatment Plant, Great Plains Region, CO Referral Number: 8540-2019-06

INTRODUCTION

Corrosivity testing was performed on two samples from the Leadville Mine Drainage Tunnel Water Treatment Plant. Samples were tested at Colorado Analytical Laboratory for resistivity, pH, and soluble chloride and sulfate concentrations.

CONCLUSIONS

• Resistivity values fall in the “moderate” range for all samples.

• pH values fall in the “neutral” range for all samples.

• Chloride concentrations fall in the “low” range for all samples.

• Sulfate concentrations fall in the “low” range for all samples.

• These results do not indicate need for special considerations on this project pertaining to corrosion of metals and sulfate attack on concrete. TSC-MCL staff has expertise in corrosion mitigation and TSC Concrete, Geotechnical, and Structural Laboratory (CGSL) staff has expertise in concrete mix design. These groups can provide additional interpretation and support, if needed.

CORROSIVITY TESTING AND RESULTS

The purpose of corrosivity testing is to quantify properties of soil that indicate a high probability for adverse reaction with buried structures, such as corrosion of metals or sulfate attack in concrete. Such properties include the concentrations of water-soluble minerals that may be dissolved and transported to the structure during periods of high precipitation. Reclamation recommends corrosivity testing for any structure, metallic or concrete, which comes in contact with soil. Corrosivity testing consists of measuring soil resistivity, pH, and the concentrations of water-soluble anions, with primary analytes being chloride (Cl-) and sulfate (SO4-2).

Samples were tested at a third-party laboratory, Colorado Analytical Laboratory. The standards used by this laboratory for corrosivity testing are:

o Resistivity – AASHTO T288-91 o pH – AASHTO T289-91 o Chlorides – AASHTO T291-91 / ASTM D4327 o Sulfates – AASHTO T290-91 / ASTM D4327

Resistivity values fall in the “moderate” range for all samples tested. The measured values for pH are within neutral limits for all samples. Chloride concentrations fall in the “low” range for all samples. Sulfate concentrations fall in the “low” range for all samples. Test results are included as Appendix A.

Table I. Corrosivity Categories

Range Values # of Samples in Range

Resistivity (Ω-cm)

Low >10,000 0 Moderate 5,000-10,000 2

Severe 2,000-5,000 0 Very Severe <2,000 0 pH Acidic <6 0 Neutral 6-9 2 Basic >9 0

Chlorides (mg/L) Low <100 2

Moderate 100-500 0 Severe >500 0

Sulfates (mg/L)

Low <1000 2 Moderate 1000-2000 0

Severe 2000-20000 0 Very Severe >20000 0 cc: 86-68190 (K. Guerra), 86-68320 (R. Lung), 86-68530 (R. Rinehart), 86-68540 (J. Torrey), 86-68320 (T. Lewis), GP-2300 (K. Roccoforte and C. Clark), 86-68311 (J. Worner), 86-68330 (J. Rittgers), 86-68313 (M. Gobla)

APPENDIX A

Appendix D

Geotechnical Laboratory testing Results for Leadville Mine

Drainage Tunnel Water Treatment Plant Foundation Material

United States Department of the Interior

PO Box 25007

Denver, CO 80225-0007

86-68530 2.2.4.23

May 23, 2019

MEMORANDUM

To: Manager, Water Treatment Group Civil Engineering Services Division, Technical Service Center, Denver, CO Attention: 86-68190 (Katherine Guerra, P.E., Civil Engineer)

From: Gergo Arany, Civil Engineer Concrete, Geotechnical & Structural Laboratory (86-68530), Technical Service Center, Denver, CO

Subject: Transmittal of TM No. 8530-2019-25, “Geotechnical Laboratory Testing Results for

Leadville Mine Drainage Tunnel Water Treatment Plant Foundation Material,” Bureau of Reclamation, Great Plains Region, CO

Attached is the Technical Memorandum (TM) documenting the geotechnical laboratory testing program to evaluate the foundation material of a potential new water treatment plant for Leadville Mine Drainage Tunnel that was submitted by Bureau of Reclamation Great Plains personnel.

If you have any questions or comments regarding this report, please contact Gergo Arany at 303-445-2389 or via email at garany@usbr.gov.

Attachment

Electronic copy CC recipients (w/att):

kguerra@usbr.gov – Katherine Guerra, TSC Team Lead mhenrick@usbr.gov – Michael Henrick, TSC Civil Engineer mgobla@usbr.gov – Michael Gobla, TSC Civil Engineer rlung@usbr.gov – Robert Lung, TSC Geologist cclark@usbr.gov – Cody Clark, GP Regional Geologist sjoramo@usbr.gov – Seth Joramo, GP Geologist rrinehart@usbr.gov – Robert Rinehart, TSC Civil Engineer

U.S. Department of the Interior Bureau of Reclamation Technical Service Center Denver, CO May 2019

Geotechnical Laboratory Testing Results for Leadville Mine Drainage Tunnel Water Treatment Plant Foundation Material Leadville Mine Drainage Tunnel Project, Water Treatment Plant Replacement

Great Plains Region, Colorado

Concrete, Geotechnical, & Structural Laboratory (CGSL) Technical Memorandum No. 8530-2019-25

Mission Statements The U.S. Department of the Interior protects America’s natural resources and heritage, honors our cultures and tribal communities, and supplies the energy to power our future.

The mission of the Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public.

Concrete, Geotechnical, and Structural Laboratory, 86-68530

Technical Memorandum No. 8530-2019-25

Geotechnical Laboratory Testing Results for Leadville Mine Drainage Tunnel Water Treatment Plant Foundation Material

Prepared by: Gergo D. Arany, M.Sc.

Civil Engineer, Concrete, Geotechnical, and Structural Laboratory, 86-68530

Checked by: Richard G. Bearce, Ph.D.

Technical Approval: Robert V. Rinehart, Ph.D., P.E.

Civil Engineer, Concrete, Geotechnical and Structural Laboratory, 86-68530

Peer Review: Tyler L. Chatfield, P.E.

iv

Contents Introduction Results and Conclusions

Soil Physical Properties Test Results

TP-18-1

TP-18-2

TP-18-3

Direct Shear Test Results Laboratory Testing Methods

Material Conditioning Gradation Analysis & Atterberg Limits Direct Shear Testing

References Physical Property Test Reports..................................................................A-1 Direct Shear Test Reports and Photos .......................................................B-1

Tables Table 1: Soil Sample Index and Test Request Summary Table 2. Summary of Physical Property Test Results Table 3. Summary of Direct Shear Test Results

Figures Figure 1: CGSL Large Soil Direct Shear Testing Machine

8530-2019-25

Introduction The Leadville Mine Drainage Tunnel (LMDT) is primarily an underground pipeline system extending from the Environmental Protection Agency (EPA) California Gulch Superfund Site at Operable Unit 6 to a water treatment plant in Leadville, CO. Originally owned by the now defunct Bureau of Mines, it was purchased by Bureau of Reclamation (Reclamation) in 1959 to be potentially used as a water conveyance feature for the Fryingpan-Arkansas Project. Due to poor water quality as a result of historic mining operations, Reclamation designed and constructed a water treatment plant that has been releasing treated water into the Arkansas River since 1991.

The current water treatment plant is nearing 30 years of service. Because of changed metal concentrations due to the 2008 addition of a groundwater well by EPA and the aging infrastructure, Reclamation has decided that plant replacement is warranted. Feasibility level designs for the new water treatment plant, including appurtenant chemical storage and feed facilities are currently being performed by Reclamation’s Technical Service Center (TSC).

A field investigation was conducted in November 2018 in an effort to characterize subsurface conditions at the site and to obtain samples for detailed laboratory testing (Lung, 2018).

Disturbed, bulk samples from three test pits were delivered to the TSC’s Concrete, Geotechnical, and Structural Laboratory (CGSL) in Denver, CO on November 7th, 2018, and assigned lab index numbers as shown in Table 1. The testing program, also detailed in Table 1, consisted of physical properties testing, consolidated-drained direct shear testing, and soil chemistry testing.

Results will be used in the evaluation of foundation stability and cathodic protection design for the new LMDT Water Treatment Plant. Testing was performed by both CGSL personnel and by Denver area contract laboratories, as noted in the text. Note that corrosion testing is reported separately by the TSC’s Material and Corrosion Laboratory in TM No. 8540-2019-06.

Results and Conclusions

Soil Physical Properties Test Results

Large bulk samples (approximately 2400 lbf of material) were received from TP-18-1 and TP- 18-2 to allow for accurate gradation testing and to provide sufficient material for direct shear testing. It is important to note that the material for the bulk samples was sorted in the field and only minus 3-inch material was delivered to CGSL. See the GP Region Geology Report for full material descriptions and test pit logs (report not available at this time). In addition to the large bulk samples, smaller samples in 5-gallon buckets from TP-18-1, TP-18-2, and TP-18-3 representing changes in material type by the field geologist were also delivered. While these samples were not large enough to provide fully representative gradations – due to maximum particle size – they were tested to confirm the field observations. Physical property test results are summarized below and in Table 2. Full gradation reports are available in Appendix A.

Geotechnical Laboratory Results for LMDT Water Treatment Plant Foundation Material

TP-18-1

Minus 3-inch material from the large bulk sample obtained from TP-18-1 from the depths of 0.0 to 10.0 ft classified as poorly graded sand with silt and gravel, (SP-SM)g, per the Unified Soil Classification System (USCS). The sample comprised of 7.6% fines, 46.4% sand, and 46.0% gravel; the sample can be considered a borderline classification of GP-GM/SP-SM due to the close proximity of sand and gravel content. The minus No. 40 U.S. sieve size material did not exhibit plastic behavior. Compaction with vibratory hammer found the maximum dry density to be approximately 135.4 lbf/ft3. Compaction with vibratory table found the minimum and maximum index unit weights to be 112.9 lbf/ft3 and 124.4 lbf/ft3, respectively.

Bucket samples representing material from 0.0 to 5.0 ft and from 5.0 to 10.0 ft also contained non-plastic material. Gradation analysis showed fines content ranging from 5.5 to 7.3% and both samples classified as poorly graded gravel with silt and sand, (GP-GM)s. Although as noted above, the plus 3-inch particles were removed by hand in the field and the bucket samples sizes were insufficient to be considered representative.

TP-18-2

Minus 3-inch material from the large bulk sample obtained from TP-18-2 from the depths of 0.0 to 10.0 ft classified as silty sand with gravel, (SM)g, per USCS. The sample comprised of 12.8% fines, 46.1% sand, and 41.1% gravel. The minus No. 40 U.S. sieve size material did not exhibit plastic behavior. Compaction with vibratory hammer found the maximum dry density to be approximately 129.7 lbf/ft3. Compaction with vibratory table found the minimum and maximum index unit weights to be 111.5 lbf/ft3 and 133.0 lbf/ft3, respectively.

A bucket sample representing material from 0.0 to 3.0 ft showed plastic behavior with a Liquid Limit (LL) of 31 and a Plasticity Index (PI) of 15 and classified as clayey sand with gravel, (SC)g with 35.7% fines. A bucket sample representing material from 3.0 to 5.0 ft showed non-plastic behavior and classified as silty sand with gravel, (SM)g with 24.3% fines. A bucket sample representing material from 9.0 to 10.0 ft showed non-plastic behavior and classified as poorly graded gravel with silt and sand (GP-GM)s with 5.8% fines. As noted above, the plus 3-inch particles were removed by hand in the field and the bucket samples sizes were insufficient to be considered representative for gradation analyses, but are considered representative for plasticity testing.

TP-18-3

A representative bulk sample was not received from TP-18-3. Bucket samples representing material from 0.0 to 5.0 ft and from 5.0 to 10.0 ft contained non-plastic material. Gradation analysis showed fines content ranging from 17.7 to 21.2% and both samples classified as silty sand with gravel, (SM)g, although as noted above, the plus 3-inch particles were removed by hand in the field and the bucket samples sizes were insufficient to be considered representative.

Direct Shear Test Results

Consolidated-drained direct shear testing on (SP-SM)g material from TP-18-1 from a depth of

0.0 to 10.0 ft showed an effective stress peak friction angle (’) equal to 44.4° and a post-peak effective stress friction angle (’pp) of 32.3o. The effective stress cohesion (c’) was assumed to be zero for remolded, free-draining, coarse-grained soil. Well-defined, peak drained shear stresses for this sample were fully developed between 2.8% and 3.6% relative horizontal strain.

Specimens exhibited only minor volume change during shear, with two specimens contracting with less than 0.3% axial strain at failure, and one specimen dilating with less than -0.2% axial strain at failure.

Consolidated-drained direct shear testing on (SM)g material from TP-18-2 from a depth of 0.0 to

10.0 ft showed ’ equal to 38.2° and ’pp equal to 33.7o. The value for c’ was assumed to be zero for remolded, free-draining, coarse-grained soil. Poorly-defined, peak drain shear stresses for this sample were developed between 4.2% and 5.5% relative horizontal strain. All specimens exhibited a small amount of dilative behavior with less than -0.9% axial strain at failure.

The results of the direct shear testing are summarized in Table 3. Full direct shear test reports and post-test shear plane photos are available in Appendix B.

Laboratory Testing Methods

Material Conditioning

Upon arrival, each large bulk sample (approximately 2400 lbf) was mixed thoroughly and reduced in size to form individual test specimens according to guidelines set by USBR 5205-89.

For all physical property and direct shear testing, the material used was again mixed thoroughly and reduced in size to create representative samples for specimen preparation. All tests on the large, bulk samples were completed by CGSL personnel unless otherwise specified. The 5-gallon bucket samples were sent to Knight-Piesold for physical property testing, while the accompanying water content specimen bags were blended and tested by CGSL personnel.

Gradation Analysis & Atterberg Limits

Gradation analyses were performed to determine the soil type of the received samples. USBR 5325-89 and 5335-89 standards were used for gradation testing. This testing was performed on oven-dry, minus 3-inch materials. To complete the classification of the samples, Atterberg limits testing was performed on air-dry, minus No. 40 material according to ASTM D4318-17. Results are summarized in Table 2, and gradation plots are available in Appendix A.

Direct Shear Testing

Consolidated-drained, soil direct shear strength testing was performed according to ASTM D3080/D3080M-11. A 12x12x6-inch (length by width by height), two-part shear box was employed for testing samples. Due to the particle size limitations of the testing equipment, the material gradation was modified according to the scalping with replacement technique as outlined by Donaghe & Torrey (1985). Samples were screened over a 1.5-inch sieve to remove plus 1.5-inch materials, and then an equivalent mass of No. 4 to 1.5-inch material was subsequently was added to replace the plus 1.5-inch material. Specimens were compacted to approximately 80% relative density (about 96% compaction per Lee & Singh, 1971) in the shear box in three, 2-inch thick lifts via manual tamping. Once the specimen was compacted, the shear box was mounted into the testing machine via a hydraulic hoist. The specimen was then inundated in a water bath prior to consolidation under a seating load provided by the shear box top plates and the weight of the loading yoke. A photograph of the direct shear test machine is provided in Figure 1.

Two test suites, consisting of testing three separate specimens consolidated at three normal stresses were performed. The separate specimens were consolidated at 1000 lbf/ft2, 2000 lbf/ft2, and 4000 lbf/ft2 (nominal) before shearing the samples; specimens at 2000 lbf/ft2 and 4000 lbf/ft2 were incrementally consolidated using a load increment ratio of one until the desired stress was reached. The specimen was allowed to consolidate until it was in a well-defined state of secondary consolidation before any shear deformations were applied.

Normal force was applied to the specimen by means of a loading yoke and a hydraulic actuator.

The normal force was manually controlled and kept constant throughout each consolidation phase. During shearing, the normal force varied slightly due to axial displacement, and the loading variation due to the inherent nature of the hydraulics. The normal force was measured with a load cell placed between the loading yoke and the top plate on the specimen.

Prior to shearing, the two box halves were gapped approximately 0.75-inch with nylon tipped bolts to decrease box friction forces. The shearing portion of the test was strain controlled via a programmable gear box and performed in a drained manner – i.e., the applied strain rate was sufficiently slow to ensure that excess pore water pressures did not develop in the specimen. For the testing performed here, a strain rate of 0.002 in/min (equal to 1% relative horizontal displacement/hour) was used. Tests were run until the relative horizontal displacement reached at least 15%. The normal and horizontal displacements were monitored with linear variable differential transformers (LVDTs), and the shear load was monitored with a strain-gage based load cell. All sensors were connected to PC-based data acquisition.

From previous direct shear testing by CGSL, box friction was measured by running direct shear tests with no soil at several different stain rates. It was determined that the average box friction force was equal to or less than 20 lbf. This average box friction force was not considered in this direct shear testing suite; the effect of the average friction force at high normal loads and low strain rate is negligible.

While the state of stress in the sheared zone is not fully known, the analysis is carried out assuming that the failure plane is horizontal, i.e., the applied normal stress is the normal stress on the failure plane and that the measured horizontal stress is the shear stress on the failure plane.

The shear stress was corrected for the changing shear surface area as straining progresses. The stress required to shear each specimen was then plotted against the relative horizontal strain.

The peak shear stresses for each testing suite are plotted against the associated normal stresses, and a best-fit line is drawn through the data. The post-peak shear stresses were picked at 15% relative horizontal displacement and similarly plotted and fitted against the associated normal stresses. This Mohr-Coulomb linear failure envelope defines the peak and post-peak drained strength parameters for the soil: the slope of the line is the ’, and the y-intercept is the c’. Since the material is normally consolidated and free-draining, c’ is assumed to be zero. The best-fit line is then fit through the origin and ’ is determined from the slope.

Note, that drained strength parameters from direct shear tests are typically higher than those obtained from triaxial shear strength testing due to the failure plane being restrained horizontally (Lambe and Whitman, 1969). Also note, that due to the stress concentrations at the gap between the boxes and the progressive nature of the failure surface, some researchers believe that the peak shear strength values from the direct shear test are less reliable than triaxial shear testing (Germaine and Germaine, 2009).

A summary of the test results is given in Table 3. Stress-strain curves, axial strain, and failure envelopes are presented in direct shear reports located in Appendix B.

References ASTM D3080/D3080M-11. (2011). “Standard Test Method for Direct Shear Test of Soils Under

Consolidated Drained Conditions,” ASTM International, West Conshohocken, PA, 2011, www.astm.org

ASTM D4253-16. (2016). “Standard Test Methods for Maximum Index Density and Unit Weight of Soils Using a Vibratory Table,” West Conshohocken, PA, 2016, www.astm.org

ASTM D4254-16. (2016). “Standard Test Methods for Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density,” West Conshohocken, PA, 2016, www.astm.org

ASTM D4318-17. (2017). “Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils,” ASTM International, West Conshohocken, PA, 2017, www.astm.org

ASTM D6913/D6913M-17. (2017). “Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis,” ASTM International, West Conshohocken, PA, 2017, www.astm.org

ASTM D7382-08. (2008). “Standard Test Method for Determination of Maximum Dry Unit Weight and Water Content Range for Effective Compaction of Granular Soils Using a Vibrating Hammer (Withdrawn 2017),” ASTM International, West Conshohocken, PA, 2008, www.astm.org

Donaghe, R. T., and Torrey III, V. H. (1985). “Strength and Deformation Properties of Earth- Rock Mixtures (No. WES/TR/GL-85-9).” Army Engineer Waterways Experiment Station Geotechnical Lab, Vicksburg, MS.

Germaine, J. T., and Germaine, A. V. (2009). “Geotechnical Laboratory Measurements for Engineers,” John Wiley and Sons, Inc., Hoboken, NJ.

Lambe, W. T., and Whitman, R. V. (1969). “Soil Mechanics,” John Wiley and Sons, Inc., New York, NY.

Lee, K. L., and Singh, A. (1971). “Relative Density and Relative Compaction.” Journal of the Soil Mechanics and Foundations Division, pg. 1042-1052.

Lung, R. (2018). “Field Exploration Request for Leadville Mine Drainage Tunnel Water Treatment Plant…