TM_8550-2025-02_Geotechnical_Laboratory_in_Support_of_Final_Design_Modifications_Heart_Butte_Dam_0002.pdf

- BUREAU OF -

RECLAMATION

GLFS TM No. 8550-2025-02

Heart Butte Dam Geotechnical Laboratory Testing in Support of Final Design Modifications

Pick Sloan Missouri Basin Program, North Dakota Missouri Basin Region 5

U.S. Department of the Interior February 2025

Mission Statements The U.S. Department of the Interior protects and manages the Nation’s natural resources and cultural heritage; provides scientific and other information about those resources; honors its trust responsibilities or special commitments to American Indians, Alaska Natives, and affiliated Island Communities.

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.

GLFS TM No. 8550-2025-02

Heart Butte Dam Geotechnical Laboratory Testing in Support of Final Design Modifications

Pick Sloan Missouri Basin Program, North Dakota Missouri Basin Region 5

Prepared: Blake O. Armstrong, PE Civil Engineer, Geotechnical Laboratory and Field Support, 86-68550

Checked: Kaitlyn Senechalle, MSc Civil Engineer, Geotechnical Laboratory and Field Support, 86-68550

Technical Approval: Evan J. Lindenbach, PE, PG Civil Engineer, Geotechnical Laboratory and Field Support, 86-68550

Peer Review: Kevin Schaeffer, PhD, PE Civil Engineer, Geotechnical Laboratory and Field Support, 86-68550

Cover Photo: Heart Butte Dam and Lake Tschida by Armstrong (Reclamation) 11/29/2023

Contents Contents ................................................................................................................. iii

Tables .................................................................................................................... iv

Figures.................................................................................................................... iv

Introduction

Background Previous Work

2014 IE FER

April 2018 CAS FER November 2018 CAS FER

2024 FD FER

Scope of Study Summary of Laboratory Test Results

Physical Properties Undrained Strength

In-situ Condition As-constructed Condition Mohr-Coulomb Failure Envelope

Permeability Summary of Laboratory Testing Methods

Physical Properties Undrained Strength Permeability

References

Appendix A. Physical Properties Test Reports

Appendix B. KoCU TRX Test Reports and Post-test Specimen Photos iii

Tables Table 1. Sample index and test completed Table 2. Summary of soil physical properties Table 3. Summary of Zone 2 TRX test results Table 4. Summary of Zone 2 constant head permeability test results

Figures Figure 1. Approximate locations of 2018 – 2019 drill holes (Wagner, 2018b)... 13 Figure 2. Approximate locations of 2024 drill holes (Reed, 2024) Figure 3. Zone 2 a) Mohr-Coulomb effective stress failure envelope and b) undrained strength slope-intercept models iv

Introduction

Background Heart Butte Dam is a 142-foot-tall earthfill dam located on the Heart River, approximately 72 miles southeast of Bismarck, ND, and impounds Lake Tschida (60,763 ac-ft at the top of active conservation elevation of 2064.5 ft). The structure was constructed between 1948 and 1949 on predominantly fine-grained, sandstone of the Fort Union Formation. Due to internal erosion issues with the outlet works, many studies have been conducted over the last 10 years including a Safety of Dams (SOD) Issue Evaluation (IE) study and Corrective Action Study (CAS) detailed in the Previous Works section below.

As a result of the CAS, a Decision Document/ Technical Report Findings (Yu, 2023) was developed by the United States Bureau of Reclamation (USBR) Technical Service Center (TSC) Geotechnical Services Division and reviewed by the Dam Safety Advisory Team (DSAT) in 2023. The following SOD recommendation was issued.

2023-SOD-A Perform final designs and construct a jet grout cutoff wall and a blanket filter drainage system (Alternative 7) to reduce static and hydrologic risks of internal erosion at Heart Butte Dam. Confirm risk reduction is achieved following construction with a Risk Reduction Verification.

To address this SOD recommendation, the current modification has three parts (Yu, 2023).

1. Jet grout the permeable sandstone foundation downstream right of the outlet works

2. Install a sand filter trench downstream left of the outlet works

3. Construct a zoned seepage berm around the outlet works

To collect design data from this modification, USBR TSC Geotechnical Services Division and Geotechnical Laboratory and Field Support group (GLFS) developed a Field Exploration Request (FER) in 2024 (Reed, 2024). The 2024 FER detailed a field investigation including drill holes DH-24-01 through -05 downstream of the dam to gather Final Design (FD) data for modifications proposed at Heart Butte Dam.

The purpose of this GLFS Technical Memorandum (TM) is to document:

• Existing Zone 2 undrained strength and permeability testing to inform stability of excavations during construction

• Drill holes DH-24-03 through -05 soil physical property test results to support the design of the sand filter trench and zoned seepage berm installations

Waxed rock core samples were collected from DH-24-01 and -02, but no testing was performed for this TM.

Previous Work A summary of salient points from previous GLFS TMs is provided in this section. TMs are available in USBR TSC Engineering and Laboratory Services Division’s (8500) archive.

2014 IE FER

In 2014, a FER was developed to investigate voids around the outlet works conduit and obtain soil physical property data on the foundation material in support of the IE. Samples were collected from core holes drilled from inside the outlet works conduit, but the holes did not penetrate the foundation rock deep enough to fully evaluate the potential seepage pathway through the foundation rock.

In August 2016, the IE was completed, and the following SOD recommendation was issued.

2016-SOD-A Initiate a Corrective Action Study to identify and evaluate modification alternatives to mitigate the risk of internal erosion failure associated with the outlet works conduit.

April 2018 CAS FER In April 2018, a FER was developed to provide supplemental data for future spillway/outlet works conduit modifications under the 2016 CAS. The CAS sought to identify and evaluate modification alternatives to mitigate the risk of internal erosion failure associated with the outlet works conduit (Wagner, 2018a). Similar to the 2014 investigation, samples were collected from core holes drilled from inside the outlet works conduit to characterize the embankment bedrock foundation materials and give particular attention to the potential for voids and/or other discontinuities within the rock foundation or along the contact of the rock foundation with the overlying concrete conduit.

At that time and prior to the formation of the GLFS, the TSC Concrete, Geotechnical, and Structural Laboratory (CGSL) conducted a geotechnical laboratory testing program on the foundation samples collected. Almost all material was classified as nonplastic (NP) and had Unified Soil Classification System (USCS) classifications of SM – silty sand to SP-SM – poorly graded sand with silt. Some gravels had strong reactions to HCl, and drained direct shear (DS) strength was relatively high. X-ray diffraction (XRD) composition analysis indicated the most significant contributions from quartz and clay (i.e., smectite and illite). The April 2018 FER also included a borrow soil investigation to evaluate potential candidates to be used as miscellaneous fill for potential future modifications. All three test pit samples from the borrow area classified as SM – silty sand. All results from that study are summarized in a 2018 preliminary Data Transmittal (DT) (Armstrong, 2018).

November 2018 CAS FER In November 2018, a second FER was completed including 10 drill holes within the dam footprint, downstream toe, and right abutment areas; laboratory testing of the foundation soil and rock; and tracer testing as a phase two investigation (Wagner, 2018b). In 2018 - 2019, drill holes were bored through the crest, mid-slope, and downstream toe to collect intact samples of embankment (Emb), Quaternary alluvium (Qal), Bullion Creek Formation shale (Sh), and Bullion Creek Formation sandstone (SS). After injecting dye into the foundation from inside the conduit, it was detected in the stilling basin over 150 ft away in just over an hour.

As part of the November 2018 FER, samples were tested for soil physical properties, permeability, erodibility, soil unconfined compressive strength (soil UCS), and rock uniaxial compressive strength (rock UCS). Jet erosion testing (JET) and permeability testing of the foundation alluvium indicated the material was erodible to extremely erodible with a vertical hydraulic conductivity (kv) of 8E-4 centimeters per second (cm/s). During JET testing, the variability of the foundation ‘bedrock’ erodibility was apparent. One sample was predominantly erodible sandstone, but the test was terminated when a very thin, erosion resistant shale vein was impinged upon and did not erode. The shale foundation lenses had UCS’s similar to stiff soil or an intermediate geomaterial. Results including Armstrong (2018) DT results were documented in a TM from the newly developed (at that time) GLFS group (Arany, 2020).

Based on the findings of the 2018 field exploration, a baseline Risk Analysis was completed in 2019 and indicated that the potential failure modes (PFMs) associated with the sandstone foundation of the outlet works conduit contributed substantial risks to the facility and risk reduction is warranted. Since the CAS alternatives developed in 2016 didn’t address the internal erosion concerns of the foundation sandstone and didn’t achieve sufficient risk reduction, developing new CAS alternatives were required. The following 2019-SOD-A was issued for developing the new CAS alternatives to achieve risk reduction (Yu, 2023).

2019-SOD-A Identify and evaluate modification alternatives to reduce the risks of internal erosion PFMs associated with various seepage paths in the backfill and the sandstone foundation of the outlet works conduit.

In 2021, a novel laboratory testing program was developed to investigate the feasibility of grouting the disaggregated sandstone (or silty sand) foundation using ultrafine grout and modified flexible wall permeameters. The assumption was made that composite reconstituted silty sand specimens (0%, 5%, and 10% fines) compacted to an equivalent in-situ density would have a similar groutability to the non-disaggregated sandstone. Five rounds of laboratory permeation testing were conducted (Lindenbach, 2021a). For all fines contents evaluated, it was concluded that the silty sand with majority fine sand could not be grouted on the laboratory scale with the proposed ultrafine grout (Lindenbach, et al., 2022).

In cooperation with the 2021 grout investigation, a field exploration was conducted to assess the feasibility of grouting sandstone downhole on the right abutment of the dam using chemical grout. Flight auger dry core (FADC) was used to get to depth. Then chemical grout was pumped downhole into the abutment foundation alluvium and sandstone. The hole did not stop taking grout, and the effort was abandoned with this behavior occurring at several target depths (Zukowski, TBD).

As part of the CAS sandstone grout testing program, a disaggregation investigation was conducted. It was suggested that the sandstone was competent when the outlet works was originally constructed but has since disaggregated, leading to weakening and susceptibility to internal erosion. Competent sandstone was soaked in solutions of hydrochloric acid, salicylic acid, sodium hexametaphosphate, and DI water (for a control) for several days. Only the fines portion of the particle size distribution increased due to deflocculation of clay clods in sodium hexametaphosphate. Sandstone disaggregation was not observed for any other solution evaluated.

Lasater (2022) has since reported on records from the 1952 Heart Butte Dam Technical Record of Construction (USBR, 1952) that stated, “The Fort Union sands were quite firm when damp but would not stand up under traffic when either very dry or very wet.” During pre-construction investigations, Reclamation’s Denver Laboratory in USBR (1950) classified the bedrock material in the channels as “Unconsolidated and uncemented, indicating that foundation consolidation was to be expected.”

It can be assumed that the term consolidation used in this 1950s report solely refers to the decrease in soil volume. True (or modern) soil consolidation refers to the decrease in volume due to compressing and expelling pore fluid from fine-grained soil such as clay or silt. Years’ worth of soil physical properties test results shows the material does not contain a significant amount of fine-grained silt or clay, and therefore would not experience substantial volume change due to consolidation. The decrease in volume must have occurred through the breakdown of the soil structure.

Further XRD and x-ray fluorescence (XRF) analyses indicate there are at least two primary sandstone units: calcitic sandstone and weakly-bonded clayey sandstone. However, the petrographer suggested reclassifying the calcitic sandstone as “calcitic limestone” based on the high calcium carbonate content (greater than 50% by weight). This is an interesting finding considering the sandstone sample chosen to disaggregate in HCl in the previous campaign did not show a reaction. This could shed some light on the variation of the calcium carbonate concentration within the sandstone unit.

Referring to the hypothesis about the foundation losing strength over time, it could be the case that the clay-bonded sandstone’s strength was much higher during construction but has since lost strength, likely due to hydration or other processes (Lindenbach, 2021b) with the calcitic sandstone (or limestone) remaining largely intact. Again, the clay content did increase when soaking sandstone in sodium hexametaphosphate, and the rest of the gradation did not show a significant change.

Additional testing in 2021 included soil physical properties, soil UCS, rock physical properties, and JET testing. A majority of the 17 specimens tested had erodibility classifications of erodible, with two extremely erodible and two moderately resistant classifications (Lindenbach, 2021b).

2024 FD FER

In September 2023, the CAS was completed, and the new 2023 SOD recommendation was issued, detailed in the Background section above (Yu, 2023). In November 2023 (prior to the completion of the 2024 FER), GLFS investigated potential commercially available sand and gravel sources to be used to construct the sand filter trench, the seepage berm’s sand filter, and the berm’s gravel drain. GLFS personnel visited 3 suppliers and sampled one sand and gravel sample from each. A Trip Report was developed to document the quarry visits (Armstrong, 2024a). Material testing included soil physical properties, durability, density, cementation potential, permeability, minerology, and general acceptability (clay lumps, friable particles, mica etc.). The results of the laboratory testing and quarry investigations are summarized in the GLFS TM, Dziedzina (2024) with Armstrong (2024a) in the Appendix.

In January 2024, the 2024 FER was completed to inform a FD modification to reduce the risk of internal erosion. In Spring 2024, Missouri Basin (MB) Regional Geology conducted a field investigation on 2 borrow areas: Downstream Left Abutment Borrow (DSLAB, TP-23-1 through TP-23-10) and Downstream Right Abutment Borrow (DSRAB, TP-23-11 through TP-23-15).

Twenty-one (21) 5-gallon bucket samples were sent to GLFS to be tested as potential borrow soil sources for miscellaneous fill during the berm construction. Per the TSC FD Team, DSLAB borrow soil candidates were not tested due to shallow bedrock encountered and therefore, the limited quantity of material available. DSRAB samples were tested for use as miscellaneous fill in berm construction. Testing was conducted by GLFS and Upper Colorado Basin Region’s (UCB) Provo Area Office (PAO) Materials Laboratory and included soil physical properties, standard Proctor and vibratory hammer compaction, dispersion potential, undrained strength, and permeability testing; see GLFS TM 8550-2024-25 (Armstrong, 2024b) for more information.

Scope of Study During the 2024 field investigation, 5 drill holes (DH-24-01 through -05) were bored downstream of the dam, near the outlet works and toe of the dam. Six (6) Tb waxed rock core samples were collected to the right of the stilling basin from drill holes DH-24-01 and -02 to inform the jet grout design (Lasater, 2025).

To inform the design of the sand filter trench and zoned berm installations, bagged soil samples were collected from drill holes DH-24-03 through -05. Nine (9) bagged soil samples of Qal and Tb were collected from drill hole DH-24-03 on the left bank of Heart River. Eight (8) Fill, Qal, and Tb samples were collected from drill hole DH-24-04 on the peninsula to the left of the stilling basin. Three (3), Zone 2 bagged samples were collected from the toe of the dam adjacent to the stilling basin sidewalk. See Figure 2 for a map of the approximate drill hole locations (Reed, 2024). The geologic investigation is detailed in Lasater (2025).

Standard soil physical properties testing was performed on the bagged soil samples from drill holes DH-24-03 through -05 by GLFS and CTL Thompson (Denver, CO). The results of the soil physical property testing are documented in this TM. A summary of the samples received, and tests conducted is provided in Table 1.

In Summer 2024, GLFS conducted an undrained strength and permeability testing program on Zone 2 material collected from the downstream midslope of the dam during the 2018 – 2019 field effort from drill hole DH-19-4 to inform the design of an excavation during construction. See Figure 1 for a map of the approximate drill hole location (Wagner, 2018b). Since Shelby tube samples were stored in a humidified room for 5 years prior to testing, care was taken to remove any corroded soil. Two (2) 3-point triaxial compression (TRX) suites were performed on reconstituted specimens compacted to the approximate in-situ and as-constructed densities. One constant head permeability test was also performed.

Summary of Laboratory Test Results The peak undrained strength (su) of the Zone 2 (SM – silty sand) material was assessed via Ko-consolidated, undrained (KoCU) TRX testing on specimens moisture conditioned and compacted to the approximate in-situ and as-constructed conditions. In-situ water content and dry unit weight of the Zone 2 material was measured from 3 Shelby tube samples from drill hole DH-19- 4, 27.4 to 49.4 ft below the midslope of the dam. The average in-situ water content and dry unit weight were equal to 13.8% and 92.0 pcf, respectively. The as-constructed water content and dry unit weight were estimated based on construction and drilling records and were equal to 11.2% and 101.8 pcf, respectively. Mohr-Coulomb failure envelopes were developed for each in-situ and as-constructed condition. The test results from the in-situ testing indicated undrained effective stress friction angle (ϕ’) and undrained effective stress cohesion (c’) were equal to 34.4° and 0 pounds per square foot (psf), respectively. As-constructed testing indicated ϕ’ and c’ were equal to

32.9 and 95.0 psf, respectively. When plotting all tests together, the overall ϕ' and c' were equal to 33.9° and 23.0 psf, respectively. The value of kv was evaluated to be 2.1E-4 cm/s.

From the 2024 investigation, the Fill material had USCS classifications that ranged from SC-SM

– silty clayey sand to (GC-GM)s – silty clayey gravel with sand. The Zone 2 material from the 2024 investigation classified as SM – silty sand. The Qal material had USCS classifications that ranged from CL – lean clay to (SP)g – poorly graded sand with gravel. The Tb material classified from s(CL) – sandy lean clay to SP-SM – poorly graded sand with silt.

Physical Properties A composite Zone 2 sample from the 2018 – 2019 investigation in drill hole DH-19-4, 27.4 to

49.4 ft below the ground surface, had a USCS classification of SM – silty sand and contained 27.9% fines, 71.6% sand, and trace gravel. The minus #40 sieve material could not be rolled to determine the plastic limit (PL), but the liquid limit (LL) was evaluated to be to 23. Average in-situ and as-constructed water contents and dry unit weights are provided above.

Three (3), Zone 2 bag samples collected from 0.0 to 8.9 ft in drill hole DH-24-05 had USCS classifications of SC-SM – silty clayey sand. Fines, sand, and gravel contents ranged from 21.7 to 27.7%, 72.1 to 76.6%, and 0.2 to 1.7%, respectively. LL and plasticity index (PI) of the minus #40-sieve-size material were very consistent and ranged from 23 to 25, and 5 to 6, respectively.

In-situ water content ranged from 11.5 to 22.7%; the water content was found to increase with depth.

Four (4), Fill bag samples, collected from 0.0 to 13.5 ft in drill hole DH-24-04, had USCS classifications of SC-SM – silty clayey sand, (SC-SM)g – silty clayey sand with gravel, and (GC-GM)s – silty clayey gravel wit sand. Fines and sand contents ranged from 18.0 to 38.8% and 33.0 to 67.0%, respectively. Gravel content ranged from 1.0 to 49.0% and appeared to be increasing with depth. The plasticity of the Fill material was very consistent with LL evaluated to be 22 and 24 and PI evaluated to be 5 and 6. In-situ water content ranged from 11.0 to 12.5%.

Nine (9), Qal bag samples, collected from 0.0 to 21.3 ft in drill hole DH-24-03 and 15.4 to 19.1 ft in drill hole DH-24-04, varied widely and had USCS classifications of CL – lean clay, (CL- ML)s – silty clay with sand, SM – silty sand, SP-SM – poorly graded sand with silt, (SM)g – silty sand with gravel, and (SP)g – poorly graded sand with gravel. Fines content ranged from

4.6 to 98.3% with an average of 39.6%, and sand content ranged from 1.7 to 93.3% with an average of 56.8%. Two samples contained gravel (16% and 17%) with a max particle size of 1 inch. Four (4) out of 9 specimens behaved plasticly with LL and PI ranging from 23 to 44 and 3 to 22 with averages of 31 and 11, respectively. In-situ water content ranged from 2.6 to 34.4% with an average of 21.2%.

Four (4) Tb samples, collected from 24.4 to 29.1 ft in drill hole DH-24-03 and from 21.6 to 26.6 ft in drill hole DH-24-04, had USCS classifications of s(CL) – sandy lean clay, SM – silty sand, and SP-SM – poorly graded sand with silt. Fines and sand contents ranged from 7.8 to 62.5% and

37.5 to 92.2%, respectively. No gravel was encountered. Two (2) out of 4 samples behaved plasticly with LL evaluated to be 28 and 31 and PI evaluated to be 3 and 11, respectively. In-situ water content was very consistent ranging from 27.4 to 28.5%.

Soil physical properties test results are summarized in Table 2. Test reports are available in Appendix A.

Undrained Strength Two (2), three-point KoCU TRX tests were conducted on reconstituted specimens of Zone 2 embankment material. Three (3) specimens were compacted to the approximate in-situ dry unit weight (92.0 pcf) and water content (13.8%), and another 3 specimens were compacted to the approximate as-constructed dry unit weight (101.8 pcf) and water content (11.2%).

In coordination with the TSC FD Team, consolidation stresses were estimated based on the assumed in-situ effective stresses in the Zone 2 during anticipate construction activities.

Specimens were saturated and consolidated to effective vertical consolidation stresses (σ’vc) of 990, 1040, 1990, 2000, 3980, and 4000 psf, reflecting overburden pressures at 11 to 44 ft below the ground surface. Consolidation data was analyzed to determine the axial strain rate for the shear phase. A conservative strain rate of 0.2% per hour was initially utilized but adjusted later to 0.5% per hour after a separate analysis revealed strain rates could be sped up making testing more efficient. Selection of failure was chosen at the point in which stress paths approached the critical state line (Kf -line) in p’-q space.

In-situ Condition The first 2 in-situ condition specimens exhibited contractive behavior when sheared, generating positive pore pressure, but the third specimen actually liquified immediately once the shear phase was initiated. This can occur when a low-density sand is sheared under a high σ’vc. An undrained strength models was developed using the su and σ’vc.

su = 0.26 σ’vc + 0 psf

As-constructed Condition The as-constructed condition specimen exhibited dilative behavior, generating negative pore pressure, and su was chosen at the point when excess pore pressure became negative. An undrained strength models was developed using the su and σ’vc.

su = 0.71 σ’vc + 0 psf

Mohr-Coulomb Failure Envelope Results were combined to develop a Mohr-Coulomb failure envelop using su and effective normal stress at failure (σ’n) where τ is shear stress.

τ = σ’n tan (33.9°) + 23 psf

A summary of the TRX testing is available in Table 3. Figure 3 presents undrained strength and effective stress analyses. Full TRX test reports and post-test specimen photos are available in Appendix B.

Permeability Constant head permeability testing was performed on a reconstituted Zone 2 specimen conditioned and compacted to the as-constructed water content and dry unit weight. The test was performed under a gradient of 2.0. The value of kv was evaluated to be 2.1E-4 cm/s. A summary of constant head permeameter test results is provided in Table 4.

Summary of Laboratory Testing Methods

Physical Properties Samples were tested for in-situ water content (ASTM D2216-19), sieve gradation (ASTM D6913-17 and USBR 5330-89), Atterberg limits (ASTM D4318-17 – Method B), USCS classifications (ASTM D2487-17), and minus #4 US sieve size material specific gravity (ASTM

D854-23) (ASTM, 2023).

Undrained Strength KoCU TRX testing was performed in general accordance with ASTM D4767-21 to determine peak undrained strength (ASTM, 2023). Composite specimens were reconstituted using tamping compaction into rigid 2-inch-diameter split molds. Once removed from the molds, the ends were squared by hand trimming to create a cylindrical specimen with a height of 4 inches keeping an aspect ratio of 2:1 (H:D).

Specimens were encased in a latex membrane, attached to drainage lines, and placed in the triaxial chamber. Saturation was accomplished via backpressure saturation to a minimum B-value of 0.95. After saturation, specimens were Ko-consolidated to target σ’vc chosen in coordination with the TSC FD Team. Axial strain continued until primary consolidation was complete and a well-defined state of secondary consolidation was established, indicating that any excess pore pressures were dissipated.

In TRX testing, Ko-consolidation involves creating a stress state in which the cell pressure (σ3 = σ2 = minor principal stress) is not equal to the axial stress (σ1 = major principal stress), but rather σ3 = Koσ1 where Ko is the coefficient of lateral earth pressure at rest. The desired vertical effective consolidation stress and vertical strain rate are input into the TRX testing software in order to guide the consolidation process. Axial strain is applied according to the input rate until the desired consolidation stress is reached. Simultaneously, the pore water pump extracts pore water at a rate equivalent to the volumetric strain rate due to the axial compression. The cell pressure is continuously adjusted to ensure there is no excess (positive or negative) pore pressure. In this way, the specimen itself dictates the value of Ko, and the specimen does not experience any lateral strain – in fact, Ko consolidation is sometimes also termed “zero-lateral strain consolidation.” Testing via this procedure allows for the stress state of the test specimen to more closely mimic the stress conditions known to exist in-situ than does the more familiar isotropic consolidation (σ3 = σ2 = σ1) method. Testing with anisotropic consolidation stresses represents best practice (Ladd and DeGroot, 2003) and is preferred to testing with isotropic consolidation which is known to give unconservative results (Germaine and Ladd, 1988).

Following consolidation, specimens were axially compressed (i.e., sheared) under undrained conditions to 20% axial strain. The strain rate was deemed slow enough based on physical properties to allow pore pressures to equilibrate throughout the specimen during undrained shearing, resulting in accurate effective stress measurements. Measured stresses were corrected for changes in cross-sectional area due to compression and the effects of the latex membrane (if greater than 5% of the peak strength). Based on the effective stress states at failure, a linear Mohr-Coulomb failure envelope was created to determine the ϕ’ and c’. Furthermore, a linear best-fit slope-intercept undrained strength model was developed using su and σ’vc.

Permeability Permeability testing was performed in general accordance with ASTM D2434-22 (Method A) to determine the coefficient of hydraulic conductivity for laminar flow of water through a soil specimen under constant head conditions (ASTM, 2023). Specimens were air dried and compacted (i.e., tamped) into a rigid-wall permeameter cell to a nominal height of 5 inches with a nominal diameter of 3 inches, which was greater than 10 times D95 particle size of the sand, the minimum requirement outlined in ASTM D2434-22. The specimen was compacted in 0.5-inch lifts to the target dry unit weight.

After compaction, drainage screens were placed on top of the specimen and a light load (approximately 5 to 10 lbf) was applied to the specimens via a spring attached to the top cap of the permeameter. The specimens were vacuum saturated from the bottom to the top using deaired water prior to testing to eliminate entrapped air within the void spaces. Flow through each specimen (from bottom to top) was initiated using a constant head tank. Two ports on the permeameter cell were connected to a double-tube manometer to measure changes in head across the specimens. Outflow was collected from the overflow port on the permeameter to determine volume and was measured over time using a handheld timer to determine flow rate (i.e., permeability).

References Armstrong, B. O. (2018). “Results of Soil Testing on Heart Butte Dam Conduit Material,” CGSL

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Lindenbach, E. J., Armstrong, B. O., Downs, J., Lucero, C., Joy, W. T., and Qiao, J. (2022). “A Novel Testing Approach to Investigate Cementitious Grout Permeation in Fine Sand,” 2022 United States Society on Dams, San Diego, CA.

Reed, A. (2024) “Field Exploration Request for Heart Butte Dam Final Design,” United States Department of Interior, Bureau of Reclamation, Technical Service Center, Engineering Geology and Geophysics, Denver, CO.

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Wagner, C. (2018a). “Field Exploration Request for Heart Butte Dam Corrective Action Study,” United States Department of Interior, Bureau of Reclamation, Technical Service Center, Engineering Geology and Geophysics, Denver, CO.

Wagner, C. (2018b). “Field Exploration Request #2 for Heart Butte Dam,” United States Department of Interior, Bureau of Reclamation, Technical Service Center, Engineering Geology and Geophysics, Denver, CO.

Yu, J. (2023). “Decision Document/ Technical Report of Findings: Corrective Action Study Preferred Alternative, Heart Butte Dam,” United States Department of Interior, Bureau of Reclamation, Technical Service Center, Geotechnical Services Division, Denver, CO.

Zukowski, Z. (Draft). “Heart Butte Dam Grout Testing Results and Analyses,” United States Department of Interior, Bureau of Reclamation, Technical Service Center, Geotechnical Services Division, Denver, CO.

EB OnllHoles

203-O-71-RD-1

□o -63

□ 6300000001 - 2ss

E9 Drill Hole DH-19-4

Note: O Drill Holes scheduled for 20 19

□ FER #3 Onll Holes t::I Dnll Hole completed during 2018

□ Drill Hole canceled

Cffl~1 "'-~ ncrt ~l'e-ei: '1a11C)l'l3!

Geogra~ wrrerr: ,i: ~ potcy Scuree-s. ~1!1aru• GeogT~phic, Esrl Del.or~ HERE. UNEP

WCMC USGS. NASA. £SA.

METl, kRCAN, GEBCO. NOAA.

0 2550 100 150 200 -- Feet

UnlodSt.itoa Oeparunen1 of the Inter.,, Bure~u of Recltmotion Pid<-sloan Missouri Basin Pr0!>'3m

Heart Division

Heart Butte Dam 2018 Field Exploration Request #2

Bo<ehole Locations Sept 2018 Figure-

Drill Hole DH-19-

Figure 1. Approximate locations of 2018 – 2019 drill holes (Wagner, 2018b).

Figure 2. Approximate locations of 2024 drill holes (Reed, 2024).

Table 1. Sample index and test completed.

Drill Hole Location Material Depth ft Sample Type

Physical Properties Permeability Consol. Shear Strength Misc.

N at ur al

W at er C on te nt , A

ST

M

D

U ni t W ei gh t, AS

TM

D

M in

/M ax

In de x U ni t W ei gh t, AS

TM

D a nd

D

G ra da tio n, A

ST

M

D

Hy dr om et er , A

ST

M

D

At te rb er g Li m its

M oi st o r A ir

Dr y, A

ST

M D

At te rb er g Li m its

O ve n Dr y, A

ST

M

D

M od ifi ed

Sp ec ifi c

G ra vi ty

, A

ST

M D

Pi n ho le

D isp er sio n Te st , A

ST

M

D

Cr um b Di sp er sio n te st

, A

ST

M D

Do ub le H yd ro m et er D isp er sio n

Te st

, A

ST

M D

Co m pa ct io n

- S ta nd ar d Pr oc to r, AS

TM

D

Co m pa ct io n

- V ib ra to ry H am m er , A

ST

M

D

Co ns ta nt h ea d Pe rm ea bi lit y, A

ST

M

D

Fl ex ib le

W al l P er m ea m et er , A

ST

M

D

M et ho d C

Fi lte r T es tin g

/ F ilt er C em en ta tio n, U

SB

R in -h ou se

Fl ow

P um p Pe rm ea bi lit y, A

ST

M

D

M et ho d D

O ne

-D im en sio na l c on so lid at io n, A

ST

M D

Sw el l/C ol la ps e, A

ST

M

D

Co ns ta nt

R at e of

S tr ai n, A

ST

M D

U nc on fin ed C om pr es siv e, A

ST

M

D

Di re ct S he ar

, A

ST

M D

Di re ct S im pl e Sh ea r, AS

TM

D

Cy cl ic S im pl e Sh ea r, AS

TM

D

U U

T ria xi al

S he ar , A

ST

M

D

CU

T ria xi al S he ar

, A

ST

M D

CD

T ria xi al S he ar

, A

ST

M D

Cy cl ic T ria xi al S he ar

, A

ST

M D

Re pe at ed

D ire ct S he ar

, A

ST

M D

M od ifi ed

Se ns iti vi ty (l ab v an e)

, A

ST

M D

JE

T

Er os io n, U

SB

R In

-h ou se

Pe tr og ra ph ic e xa m in at io n

O rg an ic

C on te nt

, A

ST

M D

Co rr os io n Su ite (p

H, S ul fa te s, C hl or id es , R es ist iv ity

DH-19-4 Mid-slope Zone 2

27.4 - 29.4

Shelby Tube, 5-inch X X

X X X X X37.4 - 39.4 X

47.4 - 49.4 X

DH-24-01

Right of Stilling

Basin Bullion Creek

Formation (Tb)

14.0 - 15.0 Waxed Core, PQ 38.0 - 39.0

45.0 - 46.0

DH-24-02

Right of Stilling

Basin Bullion Creek

Formation (Tb)

14.2 - 15.0 Waxed Core, PQ 25.2 - 26.0

41.75 - 42.85

DH-24-03

Left Bank of Heart

River

Quaternary Alluvium (Qal)

0.0 - 3.2

Bag Sample, 1-gal

X X X

5.5 - 6.5 X X X

6.5 - 7.0 X X X

8.3 - 9.1 X X X

9.7 - 10.0 X X X

13.0 - 13.8 X X X

18.1 - 21.3 X X X

Bullion Creek Formation (Tb)

24.4 - 26.6 X X X

26.6 - 29.1 X X X

DH-24-04

Peninsula Left of

Stilling Basin

Fill

0.0 - 2.3

Bag Sample, 1-gal

X X X

6.2 - 6.6 X X X

10.1 - 11.6 X X X

12.5 - 13.5 X X X

Quaternary Alluvium (Qal)

15.4 - 16.6 X X X

16.6 - 19.1 X X X

Bullion Creek Formation (Tb)

21.6 - 23.0 X X X

24.1 - 26.6 X X X

DH-24-05

Toe of Dam

Adjacent to Stilling Basin Sidewalk

Zone 2

0.0 - 2.0

Bag Sample, 1-gal X X X

3.5 - 6.4 X X X

7.3 - 8.9 X X X

Table 2. Summary of soil physical properties.

Drill Hole Location Material Depth

(ft) USCS

Particle Size Fraction Coefficients 1 Atterberg Limits 2 In-situ

Post Construction

Fi ne s

0)

Sa nd to

4)

G ra ve l to in ch

Co bb le s in ch

Co ef fic ie nt o f U ni fo rm ity C u Co ffi ci en t o f C ur va tu re

C c Li qu id

L im it

Pl as tic ity

In de x

Dr y

U ni t W ei gh t

( p cf

W at er C on te nt

Dr y

U ni t W ei gh t

( p cf

W at er C on te nt

DH-19-4 Midslope Zone 2

27.4 - 29.4

SM 27.9 71.6 0.5 0.0 - - 23 NP 92.0 13.8 101.8 11.237.4 - 39.4

47.4 - 49.4

DH-24-03

Left Bank of Heart

River

Qal

0.0 - 3.2 SM 33.2 66.8 0.0 0.0 - - 23 3 8.6

5.5 - 6.5 SP-SM 6.7 93.3 0.0 0.0 2.52 1.32 NP NP 2.6

6.5 - 7.0 (CL-ML)s 70.9 29.1 0.0 0.0 - - 25 5 20.5

8.3 - 9.1 CL 89.5 10.5 0.0 0.0 - - 32 12 34.2

9.7 - 10.0 CL 98.3 1.7 0.0 0.0 - - 44 22 34.4

13.0 - 13.8 (SP)g 4.6 78.4 17.0 0.0 3.56 0.89 NP NP 18.6

18.1 - 21.3 SM 14.8 85.2 0.0 0.0 - - NP NP 23.8

Tb 24.4 - 26.6 s(CL) 62.5 37.5 0.0 0.0 - - 31 11 28.4

26.6 - 29.1 SM 12.6 87.4 0.0 0.0 - - NP NP 28.2

DH-24-04

Peninsula Left of

Stilling Basin

Fill

0.0 - 2.3 SC-SM 31.0 67.0 2.0 0.0 - - 24 6 11.9

6.2 - 6.6 SC-SM 38.8 60.2 1.0 0.0 - - 24 6 11.3

10.1 - 11.6 (SC-SM)g 28.4 47.6 24.0 0.0 - - 24 5 12.5

12.5 - 13.5 (GC-GM)s 18.0 33.0 49.0 0.0 - - 22 5 11.0

Qal 15.4 - 16.6 (SM)g 27.3 56.7 16.0 0.0 - - NP NP 23.1

16.6 - 19.1 SP-SM 10.8 89.2 0.0 0.0 N/A N/A NP NP 25.3

Tb 21.6 - 23.0 SP-SM 7.8 92.2 0.0 0.0 2.86 1.36 NP NP 27.4

24.1 - 26.6 SM 22.4 77.6 0.0 0.0 - - 28 3 28.5

DH-24-05

Toe of Dam

Adjacent to Stilling Basin Sidewalk

Zone 2

0.0 - 2.0 SC-SM 21.7 76.6 1.7 0.0 - - 23 5 11.5

3.5 - 6.4 SC-SM 23.6 74.8 1.6 0.0 - - 24 6 18.7

7.3 - 8.9 SC-SM 27.7 72.1 0.2 0.0 - - 25 6 22.7

1 Cu = D60 / D10 ; Cc = D30 2 / ( D60 x D10 ) . If N/A, D10 was not obtained.

2 NP = Nonplastic

Table 3. Summary of Zone 2 TRX test results.

Sample Info Test Conditions Principal Stresses Mohr-Coulomb Effective Stress Undrained Strength Slope-Intercept

Drill Hole

Depth

(ft) Material LL

Li qu id L im it

PI

Pl as tic ity

In de x

Sp ec im en

C on di tio n w (%)

In iti al W at er

C on te nt γ d (pcf)

In iti al D ry U ni t W ei gh t σ ' vc (psf)

Ve rt ic al

E ff ec tiv e Co ns ol id at io n

St re ss

K o

Co ef fic ie nt o f L at er al

E ar th

Pr es su re a t R es t P os t-

Co ns ol σ ' 1f (psf)

M aj or E ff ec tiv e

Pr in ci pa l St re ss a t F ai lu re σ ' 3f (psf)

M in or E ff ec tiv e

Pr in ci pa l St re ss a t F ai lu re u (psf)

Ex ce ss P or e

W at er P re ss ur e at F ai lu re φ ' CU ( °)

U nd ra in ed E ff ec tiv e

St re ss Fr ic tio n An gl e c' CU (psf)

U nd ra in ed E ff ec tiv e

St re ss Co he si on τ ff (psf)

Sh ea r S tr es s o n Fa ilu re

P la ne at F ai lu re s u (psf)

Pe ak ed U nd ra in ed

S he ar St re ng th s u / σ ' vc

M ea su re d U nd ra in ed

St re ng th

R at io

(psf)

U nd ar in ed S tr en gt h

M od el

DH-19-4 29.4 - 49.4 Zone 2 23 NP

In-situ

13.3 95.0 1040 0.58 1249 374 235

33.9 23

363 438 0.42

0.26 σ' vc + 013.5 93.2 1990 0.66 2334 635 668 705 850 0.43

13.4 94.6 3980 0.48 2223 616 1271 667 804 0.20

As- Construction

11.0 100.9 994 0.44 2099 526 -29 653 786 0.79

0.71 σ' vc + 010.9 101.8 2002 0.60 5120 1397 6 1545 1862 0.93

10.4 100.9 4003 0.52 7297 2069 -6 2170 2614 0.65 1 Due to strain hardening behavior (no clear peak in deviator stress) failure was chosen based on analysis of the p'-q stress path as it approached the K f line.

2 NP = Nonplastic

Sh ea r S tr es s ( ps f)

As-constructed In-situ M-C Failure Envelope

0 1000 2000 3000 4000 5000 6000 7000 8000

I I I I I I I I I I I --- -

- - - 0

;r , J I i, , , I I -i""o, if'.

~ r,.

I .,, I~ ,,.... .,, 7 I'\..

I," !/ -...~ I\.

I~ ~ I 1,,.. I\. . ) -- r

1, 'f "' ' A 'J I ' \

, I\ ~ l...d,..- ' F-:: ~ I~ I ' " I

):/. r, 1, ' \ I , '(' I r \ I

--.,, ... .,, 0 --.. --, su = 0.71 σ'vc su = 0.26 σ'vc

0 500 1000 1500 2000 2500 3000 3500 4000 4500

As-constructed

In-situ

U nd ra in ed S he ar

S tr en gt h (p sf

0 0

a) Effective Normal Stress (psf) b) Effective Consolidation Stress (psf)

Figure 3. Zone 2 a) Mohr-Coulomb effective stress failure envelope and b) undrained strength slope-intercept models.

c'cu = 23 psf

Φ' cu = 33.9°

Table 4. Summary of Zone 2 constant head permeability test results.

Drill Hole Depth

(ft) Material LL Li qu id

L im it

PI

Pl as tic ity

In de x

La b

U

SC

S Cl as si fic at io n w

W at er C on te nt

S

De gr ee o f S at ur at io n γ d

Dr y

U ni t W ei gh t ( pc f) e o

In iti al V oi d

Ra tio

G s

Sp ec ifi c

G ra vi ty i

G ra di en t k

Hy dr au lic

C on du ct iv ity

(c m

/s

DH-19-4 27.4 - 49.4 Zone 2 23 NP SM 11.2 45.9 101.8 0.661 2.71 2 2.09E-04 1 Constant head permeability testing

Appendix A. Physical Properties Test Reports

Bureau of Reclamation Engineering and Laboratory Services Division

Denver Federal Center Building 56 PO Box 25007 Denver, CO 80225-0007 www.usbr.gov/tsc/tscorganization/8500.html

Material Test Report Feature/Job: Heart Butte - Final Design Region/Project: GP-Pick Sloan Missouri Basin Program

Blake Armstrong, Civil Engineer (Geotechnical)Reviewed By:

Report No: MAT:24-00213-S04 Issue No: 3

8/19/2024Date Signed:

Blake ArmstrongChecked By: 7/8/2024

99.79.5mm (3/8in) 99.54.75mm (No.4) 99.22.36mm (No.8)

99.819.0mm (¾in) 100.075.0mm (3in) 100.037.5mm (1½in)

% PassingSieve Size Limits

53.2150µm (No.100) 27.975µm (No.200) 92.1300µm (No.50) 99.01.18mm (No.16) 98.8600µm (No.30)

Date Tested: 7/3/2024

USBRSpecification Thin Wall Sampler (Shelby), 5"Sampling Method

Sample Details 24-00213-S04Sample ID Zone 2Material

DH-19-4Boring No

27.4 – 49.4 ftDepth

5/1/2029Date Sampled

Atterberg Limit:

Liquid Limit:

Plastic Limit:

Plasticity Index:

Sample Description:

Zone 2 Composite, SM - silty sand

Grading:

NP

NP

0.2643D85: 0.1693D60: 0.1374D50:

0.0794D30: N/AD15: N/AD10:

USBR 5330

Tested By: Kaitlyn Truss

Particle Size Distribution

COBBLES GRAVEL

Coarse (0.2%)

Fine (0.3%)

SAND

Coarse (0.3%)

Medium (3.7%)

Fine (67.6%)

FINES (27.9%)

Silt Clay (0.0%)

Page 1 of 4© 2000-2024 QESTLab by SpectraQEST.comForm No: 18909, Report No: MAT:24-00213-S04 A-1

Denver Federal Center Building 56 PO Box 25007 Denver, CO 80225-0007 www.usbr.gov/tsc/tscorganization/8500.html

Material Test Report Feature/Job: Heart Butte - Final Design Region/Project: GP-Pick Sloan Missouri Basin Program

Blake Armstrong, Civil Engineer (Geotechnical)Reviewed By:

Report No: MAT:24-00213-S04 Issue No: 3

8/19/2024Date Signed:

Blake ArmstrongChecked By: 7/8/2024

Sample Details

Tyler Dziedzina 2.00E-04

101.82

13.8 92.0

USBRSpecification Thin Wall Sampler (Shelby), 5"Sampling Method

24-00213-S04Sample ID Zone 2Material

DH-19-4Boring No

27.4 – 49.4 ftDepth

5/1/2029Date Sampled

Result In-Situ Dry Unit Weight (lb/ft³) ASTM D 1587

Other Test Results MethodDescription Limits

In-Situ Water Content (%) Percentage Oversize (%) ASTM D 2434 Maximum Dry Density (lb/ft³) Optimum Moisture Content (%) Relative Density (%) Moisure Content (%) Dry Unit Weight (lbf/ft³) Void Ratio Average Permeabilty (cm/s) Tested By

8/19/2024Date Tested SMGroup Symbol ASTM D 2487

Silty sandGroup Name Approximate maximum grain size ASTM D 4318 Material retained on 425µm (No. 40) (%)

Method of Removal Grooving Tool Type Specimen preparation method Drying Method Special selection process Rolling Method for PL As Received Water Content (%) Liquid Limit Device Type

23Liquid Limit NPPlastic Limit

Sample Details

Page 2 of 4© 2000-2024 QESTLab by SpectraQEST.comForm No: 18909, Report No: MAT:24-00213-S04

NP = Non Plastic Silt-clay fraction = 0.005 mm, should be 0.002 mm Comments

A-2

Denver Federal Center Building 56 PO Box 25007 Denver, CO 80225-0007 www.usbr.gov/tsc/tscorganization/8500.html

Material Test Report Feature/Job: Heart Butte - Final Design Region/Project: GP-Pick Sloan Missouri Basin Program

Blake Armstrong, Civil Engineer (Geotechnical)Reviewed By:

Report No: MAT:24-00213-S04 Issue No: 3

8/19/2024Date Signed:

Blake ArmstrongChecked By: 7/8/2024

Sample Details

8/1/2024 Kaitlyn Truss

20.0 A

2.71 2.71

7/3/2024 Kaitlyn Truss One-point (B)

NP

USBRSpecification Thin Wall Sampler (Shelby), 5"Sampling Method

24-00213-S04Sample ID Zone 2Material

DH-19-4Boring No

27.4 – 49.4 ftDepth

5/1/2029Date Sampled

Result Plasticity Index

Other Test Results MethodDescription Limits

Liquid Limit Procedure Tested By Date Tested Specific Gravity (at 20°C) ASTM D 854 Average Specific Gravity (at 20°C) Method Passing 4.75mm (No.4) (%) Test temperature (°C) Tested By Date Tested

13.8Water Content (%) ASTM D2216 7/3/2024Date Tested

Kaitlyn TrussTested By

0.26D85 USBR 5330

0.17D60 0.14D50 0.08D30 0.00D15 0.00D10

Method WetSample Obtained While

Group Name Group Symbol

NoComposite Sieving Used Dispersant by handDispersion Method

Sample Details

Page 3 of 4© 2000-2024 QESTLab by SpectraQEST.comForm No: 18909, Report No: MAT:24-00213-S04

NP = Non Plastic Silt-clay fraction = 0.005 mm, should be 0.002 mm

A-3

Denver Federal Center Building 56 PO Box 25007 Denver, CO 80225-0007 www.usbr.gov/tsc/tscorganization/8500.html

Material Test Report Feature/Job: Heart Butte - Final Design Region/Project: GP-Pick Sloan Missouri Basin Program

Blake Armstrong, Civil Engineer (Geotechnical)Reviewed By:

Report No: MAT:24-00213-S04 Issue No: 3

8/19/2024Date Signed:

Blake ArmstrongChecked By: 7/8/2024

USBRSpecification Thin Wall Sampler (Shelby), 5"Sampling Method

24-00213-S04Sample ID Zone 2Material

DH-19-4Boring No

27.4 – 49.4 ftDepth

5/1/2029Date Sampled

Result Prior Testing

Other Test Results MethodDescription Limits

Page 4 of 4© 2000-2024 QESTLab by SpectraQEST.comForm No: 18909, Report No: MAT:24-00213-S04

NP = Non Plastic Silt-clay fraction = 0.005 mm, should be 0.002 mm

A-4

DH-24-03 DH-24-03 DH-24-03 DH-24-03 DH-24-03 DH-24-03 DH-24-03 DH-24-03 DH-24-03

Sieve No. Particle Diameter (mm) 0.0'-3.2' 5.5'-6.5' 6.5'-7.0' 8.3'-9.1' 9.7'-10.0' 13.0'-13.8' 18.1'-21.3' 24.4'-26.6' 26.6'-29.1'

3 in. 0.762

1.5 in. 3.81 100 1 in. 2.54 88

0.75 in. 1.905 88

0.5 in. 1.27 85

0.375 in. 0.9525 85 #4 4.75 100 83 #8 2.38 99 80 100

#16 1.19 98 76 100 99 #30 0.59 97 100 100 70 99 100 99 #50 0.297 92 80 98 100 39 86 99 95

#100 0.149 57 16 87 98 100 11 33 85 24 #200 0.074 33.2 6.7 70.9 89.5 98.3 4.6 14.8 62.5 12.6

23 N/L 25 32 44 N/L N/L 31 N/L 3 N/P 5 12 22 N/P N/P 11 N/P

8.6 2.6 20.5 34.2 34.4 18.6 23.8 28.4 28.2

US Bureau of Reclamation Heart Butte Dam Project No. DN51045-300

Table 1

Particle Size Distributions Percent Passing

Moisture Content (%) Plasicity Index (%)

Liquid Limit (%) Table 2

A-5

DH-24-04 DH-24-04 DH-24-04 DH-24-04 DH-24-04 DH-24-04 DH-24-04 DH-24-04

Sieve No. Particle Diameter (mm) 0.0'-2.3' 6.2'-6.6' 10.1'-11.6' 12.5'-13.5' 15.4'-16.6' 16.6'-19.1' 21.6'-23.0' 24.1'-26.6'

3 in. 0.762 100 100 100

1.5 in. 3.81 91 86 91 1 in. 2.54 89 72 89

0.75 in. 1.905 86 65 86

0.5 in. 1.27 81 59 85

0.375 in. 0.9525 100 100 79 56 85 #4 4.75 98 99 76 51 84 #8 2.38 97 98 74 45 83 100

#16 1.19 96 97 72 42 82 99 #30 0.59 95 96 71 40 81 100 99 100 #50 0.297 89 89 68 37 76 94 72 97

#100 0.149 50 59 45 27 46 46 16 49 #200 0.074 31.0 38.8 28.4 18.0 27.3 10.8 7.8 22.4

24 24 24 22 N/L N/L N/L 28 6 6 5 5 N/P N/P N/P 3

11.9 11.3 12.5 11.0 23.1 25.3 27.4 28.5

US Bureau of Reclamation Heart Butte Dam Project No. DN51045-300

Table 4 Liquid Limit (%)

Plasicity Index (%) Moisture Content (%)

Table 3

Particle Size Distributions Percent Passing

A-6

Sample of SAND, SILTY (SM) GRAVEL 0 % SAND 67 % From DH - 24-03 AT 0-3.2 FEET SILT & CLAY 33 % LIQUID LIMIT 23

PLASTICITY INDEX 3

Sample of POORLY GRADED SAND WITH SILT (SP-SM) GRAVEL 0 % SAND 93 % From DH - 24-03 AT 5.5-6.5 FEET SILT & CLAY 7 % LIQUID LIMIT NL

PLASTICITY INDEX NP

U.S. BUREAU OF RECLAMATION

U.S. BUREAU OF RECLAMATION

CTL|T PROJECT NO. DN51,045.000.300

FIG. 1

Gradation Test Results

0.002

15 MIN.

.005

60 MIN.

.009

19 MIN.

.019

4 MIN.

.037

1 MIN.

.074

*200

.149

*100

.297

*50

0.42

*40

.590

*30

1.19

*16

2.0

*10

2.38

*8

4.76

*4

9.52

3/8"

19.1

3/4"

36.1

1½"

76.2

3"

5"

6"

8"

.001

45 MIN.

CLAY (PLASTIC) TO SILT (NON-PLASTIC)

SANDS

FINE MEDIUM COARS

GRAVEL

FINE COARSE COBBLES

DIAMETER OF PARTICLE IN MILLIMETERS

25 HR. 7 HR.

HYDROMETER ANALYSIS SIEVE ANALYSIS

TIME READINGS U.S. STANDARD SERIES CLEAR…