Geological_Report_Final_Design_0005.pdf

Geologic Report for Final Design – Cle Elum Dam Fish Passage Facilities Yakima River Basin Integrated Water Resource Management Plan Yakima Project, Washington

U.S. Department of the Interior Bureau of Reclamation

Pacific Northwest Region Regional Resource & Technical Services Geology & River Systems Analysis Group

Boise, Idaho May 2014

Mission of the Department of the Interior

Protecting America’s Great Outdoors and Powering Our Future

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.

Mission of the Bureau of Reclamation

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.

Cover Photograph: View looking northwest at Reclamation drill rig set-up on drill hole (DH-13-16) near the proposed Fish Passage Multilevel Intake Structure, Lake Cle Elum in background. Cle Elum Dam Fish Passage Structure – Yakima Project, Washington – Bureau of Reclamation. Photograph by T. Maguire, September 19, 2013.

Geologic Report for Final Design – Cle Elum Dam Fish Passage Facilities Yakima River Basin Integrated Water Resource Management Plan

Yakima Project, Washington

Prepared by Donnie N. Stelma, Geologist Under general supervision of Richard A. Link, Regional Geologist

U.S. Department of the Interior Bureau of Reclamation Pacific Northwest Region Regional Resource & Technical Services Geology & River Systems Analysis Group Boise, Idaho

May 2014

Acronyms

AEP annual exceedence probabilities bpf blows per foot

DS drive samples

FER Field Exploration Request

MERL Material Engineering Laboratory

PN Pacific Northwest

PSHA probabilistic seismic hazard analysis

SPT standard penetration tests

TSC Technical Service Center

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Table of Contents

Page

Acronyms

Summary and Conclusions ........................................................................................................... v

Introduction

Purpose

Location

Previous Investigations

Current Investigations

Regional Geology

Seismicity

Site Geology

Glacial Ice-contact Lakebed Sediments (Qgi)

Glacial Till (Qgt)

Glacial Outwash (Qgol)

Engineering Geology

Multilevel Intake Structure

Testing and Sampling

Helix (transition) Structure

Testing and Sampling

Juvenile Bypass Conduit

Testing and Sampling

Outlet Works Rehabillitation Construction Geology

Adult Collection Facility

Testing and Sampling

Gravity Permeability Testing

Instrumentation

Corrosivity and Concrete Aggregate Testing

Geophysical Testing

Reference Reports and Memorandums ii May 2014 – Cle Elum Dam Fish Passage Facilities Geologic Report

Table of Contents (Continued)

Figure

Figure 1. Vicinity Map

Tables

Table 1. Results of drill hole gravity permeability testing Table 2. Summary of Slotted-pipe Piezometer Installations

Photographs

Photograph 1. View looking south (downstream) at the ground surface in the area Photograph 2. Close-up view of fine-grained Glacial Ice-contact (Qgi) material Photograph 3. View of excavation in Glacial Till (Qgt) from the main borrow pit Photograph 4. View of Glacial Outwash (Qgo1) exposed at the portal Photograph 5. View of Glacial Outwash (Qgo1) in the stilling basin excavation Photograph 6. View of drift excavation and lining (timber) work Photograph 7. View of Glacial Outwash (Qgo1) exposed during tunneling work

Appendices

Appendix A – TSC Memorandum – Field Exploration Request (FER)

Appendix B – Summary of Drilling, Geologic Logs with photographs of soil

Appendix C – Laboratory Data – Summary Sheets – Laboratory Moisture, Gradation and Soil Consistency Data (drill holes) TSC Memorandum – Corrosivity Testing TSC Memorandum – Evaluation of Proposed Concrete Aggregate-Final Design

TSC Memorandum – Petrographic Examination of Concrete Aggregate

Appendix D – Geophysical Data

TSC Memorandum – Seismic Refraction Survey Data

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Table of Contents (Continued)

Appendix E – Drawings Drawing No. 33-100-6148 – Geologic Legend, Explanation and Notes Drawing No. 33-100-6149 – Geologic Plan Map and Location of Explorations Drawing No. 33-100-6150 – Geologic Section A-A’ Drawing No. 33-100-3394 – Cle Elum Dam - Rehabilitation of Outlet Works – Stacked Drift Configuration Drawing No. 33-D-4000 – Cle Elum Dam - Rehabilitation of Outlet Works – General Longitudinal Section iv May 2014 – Cle Elum Dam Fish Passage Facilities Geologic Report

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Summary and Conclusions This report presents the results of geologic investigations conducted in 2013 as part of the Yakima River Basin Integrated Water Resource Management Plan which includes providing fish passage at existing reservoirs within the basin. Field investigations were performed to gather data to evaluate the characteristics of the foundation for the fish passage structures at Cle Elum Dam, Washington. The 2013 field investigations included standard penetration tests, gravity permeability tests, obtaining soil samples for laboratory analysis, installing piezometers in foundation materials, and surface geophysical (seismic refraction) testing.

• Geologic investigations included soil sampling and testing in sixteen drill holes. Soil samples of foundation materials for the structures were obtained using various methods depending on the subsurface conditions and available equipment. Two testing and sampling methods were employed during the investigation: (1) standard penetration testing; and (2) split-tube drive sampling. Gravity water tests were conducted in 13 of the holes drilled.

• Standard penetration tests were performed in the glacial ice-contact lakebed sediments (Qgi) in drill holes DH-13-12 through -16. Uncorrected blow counts in the glacial ice-contact lakebed sediments ranged from a low of 15 blows per foot (bpf) to a maximum of 80 blows for 0.2 feet of penetration. Based on laboratory classifications the material is composed primarily of Silty Sand with Gravel (SM)g with scattered Sandy Silt s(ML), Poorly Graded Sand with Silt (SP-SM), Silty Gravel with Sand (GM)s and Well-graded Gravel with Silt and Sand (GW-GM)s layers.

• The glacial ice-contact sediments (Qgi) form the foundation for the upstream portion of the Multilevel Intake Structure. This layer is the primary water barrier holding the reservoir and penetration or damage to this layer could lead to unforeseen seepage problems downstream of the reservoir. Hence, care should be taken when penetrating the glacial ice-contact lakebed sediments to maintain the integrity of the layer by replacing the material into the fill or by using suitable fine-grained material to backfill around any structure.

• Standard penetration tests were performed in the glacial till (Qgt) in drill holes DH-13- 6, and -8 through -14. Uncorrected blow counts in the glacial till ranged from a low of 28 bpf to a maximum of 80 blows for 0.2 feet of penetration. Numerous discontinued tests were recorded as refusal due to the presence of coarse gravel and over-size (plus 3-inch diameter) material. Based on laboratory classifications the material is composed primarily of Silty Sand with Gravel (SM)g with layers of Well-graded Gravel with Silt and Sand (GW-GM)s, Poorly Graded Gravel with Silt and Sand (GP- GM)s, Poorly Graded Sand with Silt and Gravel (SP-SM)g, and scattered zones of Silt with Sand s(ML) and Clayey Gravel with Sand (GC)s.

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• Standard penetration tests were performed in the glacial outwash (Qgo1) in drill holes DH-13-1A, -3 and -5 through -13. Uncorrected blow counts in the glacial outwash counts ranged from a low of 69 bpf to a maximum of 100 blows for 0.2 feet of penetration. Numerous discontinued tests were recorded as refusal due to the presence of coarse gravel and over-size (plus 3-inch diameter) material. Based on laboratory classifications the material is composed primarily of Well-graded Gravel with Sand (GW)s, Poorly Graded Gravel with Sand (GP)s, Well-graded Gravel with Silt and Sand (GW-GM)s and Poorly Graded Gravel with Silt and Sand (GP-GM)s.

• The hydraulic conductivity values determined from gravity permeability tests for the glacial outwash (Qgo1) and glacial till (Qgt) geologic units are typical of silty sand to coarse clean sand materials. Values for the glacial ice-contact sediments (Qgi) are typical of silty sand to fine, clean sand materials.

• Single slotted-pipe piezometers were installed in eight holes drilled at the dam during the field investigations. The piezometer influence zones are all in glacial outwash (Qgo1) material. Groundwater levels recorded in November 2013 upon completion of the field investigation were generally below the invert depths of the proposed fish passage structures. Groundwater is shallower in the vicinity of the Adult Collection Facility due to direct influence from the Cle Elum River. The newly installed piezometers were equipped with vibrating-wire pressure transducers and data loggers for continuous monitoring of water levels.

• Technical Service Center (TSC) personnel conducted chemical analysis for a cathodic protection and laboratory testing to evaluate the glacial till and glacial outwash for concrete aggregate. Soil samples for testing were obtained from drill holes DH-13- 2A, -4 and -7 and test pits TP-13-1 and -2. Detailed memorandums presenting the finding of testing performed by the Technical Service Center are included in the appendices of this report.

• TSC personnel conducted seismic refraction tomography surveys along the Cle Elum Dam fish passage structure alignment. A detailed report of the geophysical survey is presented in a memorandum included in the appendices of this report.

Introduction

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Introduction This report presents the results of geologic investigations conducted in 2013 as part of the Yakima River Basin Integrated Water Resource Management Plan which includes providing fish passage at existing reservoirs within the basin.

The proposed Cle Elum fish passage facilities include both downstream juvenile and upstream adult passage. The downstream passage facilities include a multilevel intake and helical (transition) structures, and a conduit through the right abutment of the dam that would discharge flows into the spillway stilling basin. The proposed juvenile downstream passage intake would be located upstream from the existing spillway inlet channel. The upstream adult fish passage facilities include a barrier dam spanning the width of the Cle Elum River, a fish ladder and a collection facility. The barrier dam is designed to block upstream fish movement and to direct fish to the ladder entrance. These structures would be located immediately downstream from the spillway stilling basin.

Field investigations were performed to gather data to evaluate the characteristics of the foundation for the fish passage structures at Cle Elum Dam, Washington. The 2013 field investigations included standard penetration tests, gravity permeability tests, obtaining soil samples for laboratory analysis, installing piezometers in foundation materials, and surface geophysical (seismic refraction) testing.

Purpose

This document presents information obtained from geologic investigations conducted by staff of Reclamation’s Pacific Northwest (PN) Region Geology and River Systems Analysis Group, Boise, Idaho for use by the engineering technical team for design of fish passage structures at Cle Elum Dam. The investigations were performed to determine the physical and engineering properties of the foundation and provide instrumentation for monitoring variations of water levels within foundation materials.

Location

Cle Elum Dam is located on the Cle Elum River about eight miles north of the town of Cle Elum in central Washington, as shown on the vicinity map in Figure 1.

Previous Investigations

Geologic investigations of the site for Cle Elum Dam were begun as early as 1905 when the initial explorations were conducted for a timber crib dam built later that same year. Additional

2 May 2014 – Cle Elum Dam Fish Passage Facilities Geologic Report explorations were performed intermittently to evaluate a large storage dam downstream of the timber crib dam in the period from 1905 to preconstruction activities in 1931 when construction of the present dam was begun. A major rehabilitation of the outlet works tunnel was undertaken from 1978 to 1981 to correct mechanical gate problems related to surging and pulsations during periods of high flow. A large diameter pump well and four observation wells were drilled on or adjacent to the crest of the dam in the immediate vicinity of the gatehouse to design a dewatering system for the rehabilitation work. The rehabilitation included replacement of a goose-neck section of the outlet tunnel immediately downstream from the gate shaft and all excavations related to this work were mapped in detail to document the excavation geology and site conditions. A geologic investigation of the area downstream of the embankment near the stilling basin was conducted in 1981 to evaluate the feasibility of constructing a powerplant at the downstream portal of the outlet works tunnel. The modification decision analysis for Cle Elum Dam was initiated as part of the Safety of Dams program to evaluate the performance of the structure under static, hydrologic or flood and seismic loading conditions. The 1992 and 1998 field exploration programs including testing and sampling in boreholes, down hole geophysical surveys, and surface geophysical surveys.

Geologic investigations performed for proposed fish passage facilities in 2006 consisted of two holes along the right abutment area in the vicinity of the current investigations. Information from these investigations is included in following reports:

• Bureau of Reclamation, 1982, Geologic Feasibility Report, Cle Elum Dam Powerplant, Yakima Project, Washington, Bureau of Reclamation, Boise, Idaho.

• Bureau of Reclamation, 2005, (Draft) Geologic Report on Investigations for Modification Decision Analysis, Safety of Dams Program, Cle Elum Dam, Yakima Project, Washington, Bureau of Reclamation, Boise, Idaho.

• Bureau of Reclamation, 2006, Geologic Summary for Cle Elum Dam, Yakima Dams Fish Passage Project, Yakima Project, Washington, Bureau of Reclamation, Boise, Idaho.

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Figure 1. Vicinity Map

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Current Investigations

The current geologic exploration program was performed in accordance with the memorandum entitled Field Exploration Request (FER), Cle Elum Fish Passage Modification, Yakima Integrated Plan, Yakima Project, Washington, Technical Service Center (TSC), Denver, Colorado, dated September 10, 2013. The FER memorandum is included in Appendix A.

These investigations were requested to obtain data for use in the final design level evaluation for the proposed Cle Elum Fish Passage Project. The PN Region Drill Crews performed the drilling and sampling work.

The current investigation consisted of soil sampling and testing in sixteen drill holes: (1) two located downstream near the adult collection facility, (2) eight along the alignment of the juvenile bypass conduit, (3) three at the helical (transition) structure and (4) three along the alignment of the multilevel intake structure. Exploration work included drilling and sampling using standard penetration tests (SPT) and large diameter drive sampling methods and permeability testing to determine foundation characteristics and conditions for both open-excavation and tunneling construction methods. Eight of the drill holes were completed as monitoring wells. For locations of drill holes refer to Drawing No. 33-100-6149. Locations of Geologic Explorations are included in Appendix E. Geologic logs of the drill holes and test pits are included in Appendix B.

Soil samples of foundation materials for the structures were obtained using various methods depending on the subsurface conditions and available equipment. The exploration work in the drill holes located right of the existing spillway stilling basin and along the upper right abutment was performed using either a rock bit while advancing the steel casing using top-drive pneumatic hammer, or the ODEX down-hole hammer system. Drilling and sampling in the shallow drill holes located in the reservoir basin were performed using hollow-stem flight augers and casing advancers when difficult conditions were encountered. Two testing and sampling methods were employed during the investigation: (1) standard penetration testing and

(2) split-tube drive sampling.

Standard penetration tests were performed using two methods to advance the sampler: (1) the rope and cathead method and (2) a CME brand automatic hammer. Standard penetration tests were conducted on 5- and 10-foot intervals; samples were visually classified in the field and submitted for laboratory analysis. Standard penetration test energy measurements for the CME 850 track-mounted drill with CME automatic hammer range from 89.7 to 90.1 percent. Energy measurements for the rope and cathead equipment are not available.

Actual use of the SPT in the Cle Elum field program was largely ineffective due to the coarse-grained nature of the foundation materials. In most instances, the glacial till and outwash material included particles larger than the diameter of the SPT sample barrel, resulting in very limited penetration into the test intervals. Drive samples were collected to obtain samples which were too coarse grained to permit testing with the SPT barrel.

Regional Geology

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Drive samples (DS) of the coarse-grained glacial till and outwash materials were collected using a 3.5-inch inside diameter by 1.5 foot long heavy-wall, split-spoon sampler. The drive sampler was used to recover field samples which were too coarse grained to permit effective testing and sampling with the SPT barrel. The sampler was attached to the API drill rods used for rotary drilling and advanced into the formation using a bonnet or sleeve attachment which was fitted onto the end of the drill string and was sized to accommodate the pneumatic down-hole hammer. The hammer was then used to drive the sample barrel with an action similar to a jack hammer. This method proved fairly effective in advancing the sample barrel and large cobbles were often cored by the shoe of the barrel.

Samples recovered during drilling were logged and visually classified using methods described in USBR 5005 [Earth Manual, Part 2, Third Edition, and the Unified Soil Classification System (USCS)]. Classifications and descriptors of soil and rock samples are defined in the Engineering Geology Field Manual, Volume 1, Second Edition (Reclamation 1999). Standard penetration testing was performed in accordance with Reclamation test procedure USBR – 7015 and ASTM standards D-1586-08A and D-6066-96R04. Samples were submitted for physical properties and gradation analysis by the Mid-Pacific Construction Office (Willows, California) and Materials Engineering Group (Lab) Provo Area Office (Provo, Utah). The results of the laboratory testing are summarized on the geologic logs in Appendix B and on laboratory moisture, gradation and soil consistency data sheets in Appendix C.

Test pits were excavated to obtain samples which were submitted to the TSC’s Material Engineering Laboratory (MERL), Denver, Colorado for concrete aggregate quality testing.

Soil obtained using the large diameter drive sampling method from drill holes were also submitted to the MERL for corrosivity testing. Detailed test results are presented in memorandums prepared by TSC in Denver which are included in Appendix C.

TSC personnel conducted surface seismic refraction tomography surveys in the vicinity of the proposed fish passage structures. Detailed results of the geophysical testing are presented in a separate memorandum prepared by the TSC which is included in Appendix D.

Regional Geology The valley of the Cle Elum River drains a large basin on the east flank of the northern Cascades that is underlain by a sequence of intrusive and strongly deformed metamorphic rocks of probable Late Jurassic to Cretaceous age. Unconformably overlying the older rocks is a thick sequence of Eocene sedimentary and volcanic rocks, which crop out along the reservoir.

Successive multiple advances of alpine glaciers during the Pleistocene have formed the U-shaped valley in which the dam and reservoir are sited. The youngest of several terminal moraines/outwash complexes deposited during the most recent Pleistocene glacial advance essentially blocked drainage of the valley. Following deglaciation, a lake formed behind this natural dam. The natural dam was subsequently breached, and a deep channel was incised through moraine and outwash deposits, forming the modern outlet of Lake Cle Elum.

Site Geology

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For a complete discussion of the tectonic setting and regional geology, refer to the Geologic Summary for Cle Elum Dam, Yakima Dams Fish Passage Project, Yakima Project, Washington, Bureau of Reclamation, Boise, Idaho (Reclamation 2006).

Seismicity

Seismic hazards at the Cle Elum Dam are present in terms of ground motion as a function of annual exceedance probability. Seismic sources incorporated into the probabilistic seismic hazard analysis (PSHA) consisted of six faults, which include fault sources within about 100 km of the dam, two zones associated with the Cascadia subduction zone, three seismic source zones in the Cascade range, and five background (random) regional source zones. The hazards associated with all potential sources of earthquakes are combined to estimate the total mean hazard to the dam. For annual exceedence probabilities (AEP), the estimated high frequency (PH) is 0.38 g for a return period of 10,000 years, and 0.58 g for a 50,000-year return period.

The estimated 1.0 second spectral acceleration hazard, is 0.49 g for a return period of 10,000 years and 0.80 for a 50,000-year return period (Reclamation 2003).

Site Geology The geology of Cle Elum Dam is described in detail in the Geologic Summary for Cle Elum Dam, Yakima Dams Fish Passage Project, Yakima Project, Washington, Bureau of Reclamation Boise, Idaho (Reclamation 2006). The embankment and foundation geologic units encountered during the current exploratory drilling (2013) are described in the following sections from youngest (recent) to oldest, and on the geologic explanation on Drawing No. 33- 100-6148 in Appendix E. Refer to Drawing Nos. 33-100-4149 and -6150 for surface locations and subsurface configurations of the geologic units. The stratigraphic sequence present in the foundation of proposed fish passage structure at Cle Elum Dam consists of Glacial Ice-contact Lakebed Sediments (Qgi), Glacial Till (Qgt) and Glacial Outwash (Qgo1).

Glacial Ice-contact Lakebed Sediments (Qgi)

The glacial ice-contact lakebed sediments are composed chiefly of sand and silt with gravel, the unit is over consolidated due to loading from Pleistocene glacial ice. Chiefly lakebed sediments gouged from the floor of Lake Cle Elum by an alpine glacier and deposited on the upstream side of the terminal moraine impounding the present lake, this unit is poorly exposed in outcrop due to overlying cover of wave-worked beach deposits and shoreline drift derived from adjacent till deposits and in wave-cut benches along the extreme right abutment of the dam (see Photographs 1 and 2). Fine-grained lacustrine sediments ranging in thickness from 25 to 45 feet blanket the floor of the reservoir upstream from the dam, effectively preventing excessive reservoir leakage through the semi-pervious glacial till and outwash materials (Reclamation 2005). The unit was encountered in drill holes DH-13-12 through -16, see

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“Engineering Geology” section. Based on laboratory classifications the material is composed primarily of Silty Sand with Gravel (SM)g with scattered Sandy Silt s(ML), Poorly Graded Sand with Silt (SP-SM), Silty Gravel with Sand (GM)s and Well-graded Gravel with Silt and Sand (GW-GM)s layers. Thickness varies from about 30 to 50 feet based on 2013 drilling information. The unit forms the foundation for the upstream section of the multilevel intake structure.

Photograph 1. View looking south (downstream) at the ground surface in the area of the multilevel intake structure. Note the fine-grained Glacial Ice-contact (Qgi) material in lower right foreground near the rock hammer and the drill rig set-up on DH-13-16 in background. Cle Elum Dam Fish Passage, Yakima Project, Washington – Bureau of Reclamation.

Photograph by T. Maguire, September 21, 2013.

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Photograph 2. Close-up view of fine-grained Glacial Ice-contact (Qgi) material exposed in the reservoir basin in the vicinity of the multilevel intake structure. Cle Elum Dam Fish Passage, Yakima Project, Washington – Bureau of Reclamation. Photograph by T. Maguire, September 21, 2013.

Glacial Till (Qgt)

The glacial till is composed chiefly of gravel, sand and silt with cobbles and boulders. The glacial till includes large erratic boulders up to 6 feet in size. The unit appears to be homogeneous with no apparent bedding or stratification. Variably compact, ranging from dense to loose, the material within reservoir basin is susceptible to wave-induced erosion. The glacial till is chiefly ice-contact materials deposited by a Pleistocene alpine glacier forming the terminal moraine which dammed the Cle Elum River and created natural Lake Cle Elum. The moraine crest was used as the primary borrow source for the impervious section of the dam embankment, especially the area right of the existing spillway (see Photograph 3). The unit was encountered in drill holes DH-13-6 through -14, see “Engineering Geology” section.

Based on laboratory classifications the material is composed primarily of Silty Sand with Gravel (SM)g with layers of Well-graded Gravel with Silt and Sand (GW-GM)s, Poorly Graded Gravel with Silt and Sand (GP-GM)s, Poorly Graded Sand with Silt and Gravel (SP- SM)g, and scattered zones of Silt with Sand s(ML) and Clayey Gravel with Sand (GC)s.

Thickness varies from about 20 to 80 feet based on 2013 drilling information. The unit forms the foundation for the middle section of the multilevel intake structure.

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Photograph 3. View of excavation in Glacial Till (Qgt) from the main borrow pit located on the upper right abutment of Cle Elum Dam. Cle Elum Dam Fish Passage, Yakima Project, Washington

– Bureau of Reclamation. Photograph by C. Anderson, August 16, 1932.

Glacial Outwash (Qgo1)

Based on data from subsurface explorations the glacial outwash unit is subdivided into two sub-units, a coarse grained outwash (Qgo1) and a fine grained outwash (Qgo2). The fine-grained outwash unit was not encountered during investigations for the fish passage facilities, and is therefore not described here. It is likely present at depth based on previous explorations performed for the dam safety evaluation of the structure. The coarse-grained outwash (Qgo1) sub-unit is described below.

The coarse-grained outwash is composed chiefly of gravel, sand and cobbles with scattered boulders up to 24 inches in size. The unit is crudely stratified, with irregular layers, lenses and stringers of fine sand and silt and occasional lenses of openwork gravel. It is variably compact ranging from dense to loose. The outwash is composed chiefly of fluvial sediments deposited by glacial melt water forming a large outwash plain or apron downstream from the terminal moraine at Lake Cle Elum. The unit was encountered in drill holes DH-13-1A through -13, see “Engineering Geology” section. Based on laboratory classifications the material is composed primarily of Well Graded Gravel with Sand (GW)s, Poorly Graded Gravel with Sand (GP)s, Well Graded Gravel with Silt and Sand (GW-GM)s and Poorly Graded Gravel with Silt and Sand (GP-GM)s. Thickness is variable up to a maximum of 130 feet in explorations at the dam. The unit was not penetrated during the 2013 investigation. The glacial outwash forms

10 May 2014 – Cle Elum Dam Fish Passage Facilities Geologic Report the foundation for the downstream section of the multilevel intake structure, the helical (transition) structure, juvenile bypass conduit and adult collection facility. The outwash unit was also observed during original construction of the dam in excavations for the outlet tunnel conduit, spillway chute, stilling basin and downstream river channel enlargement (see Photographs 4 and 5). For additional descriptions of the glacial outwash refer to “Outlet Works Rehabilitation Construction Geology” section.

Photograph 4. View of Glacial Outwash (Qgo1) exposed at the portal of the outlet tunnel conduit excavation. Photograph taken during construction of Cle Elum Dam. Cle Elum Dam Fish Passage, Yakima Project, Washington – Bureau of Reclamation. Photograph by R.J. Newell, October 29, 1931.

Engineering Geology

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Photograph 5. View of Glacial Outwash (Qgo1) in the stilling basin excavation taken during construction of Cle Elum Dam. Cle Elum Dam Fish Passage, Yakima Project, Washington – Bureau of Reclamation. Photograph by C. Anderson, August 3, 1932.

Engineering Geology A field exploration program was prepared by the TSC to obtain data for design of the fish passage structure. The investigation included drilling and sampling in sixteen drill holes (DH- 13-1A through -16). The proposed facility includes juvenile downstream passage consisting of a Multilevel Intake Structure, Helical (transition) Structure and Juvenile Fish Passage Bypass Conduit. An Adult Collection Facility will be located in the existing spillway stilling basin area where adult fish are be captured and placed in transport trucks and delivered to upstream locations around the reservoir. Refer to Drawing No. 33-100-6149 for approximate locations of the proposed fish passage structures.

Geologic logs of the drill holes and test pits, and photographs of samples and excavations are included in Appendix B. Laboratory test data on samples obtained are included in Appendix C.

For locations of drill holes and test pits refer to Drawing Nos. 33-100-6149 and -6150 in Appendix E.

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Multilevel Intake Structure

The multilevel intake structure will consist of a rectangular concrete structure with multiple inlets and outlets to allow the release of fish passage flows in the upper 50 feet (approximate) of the reservoir pool.

Three exploratory holes (DH-13-14 through -16, inclusive) were drilled to obtain samples and determine the properties of the subsurface materials in the reservoir basin (refer to Drawing Nos. 33-100-6149 and -6150). For a detailed description of overburden and foundation materials recovered from these drill holes, refer to the logs of exploration and sample photographs in Appendix B. Laboratory test results are included in Appendix C.

Testing and Sampling

DH-13-16 is located near the upstream end of the proposed intake structure. Due to steep ground surface conditions the hole was moved approximately 20 feet south of the original location (refer to Drawing Nos. 33-100-6149 and -6150 for hole location). The hole was advanced to a total depth of 51.2 feet. The foundation material consists of glacial ice-contact lakebed sediments (Qgi). Nine standard penetration tests were performed in the material with blow counts ranging from 2 bpf to 50 blows for 0.2 feet of penetration. Laboratory classifications of the samples were primarily Silty Sand (SM). Groundwater was not encountered during drilling.

DH-13-15 is located near the upstream section of the proposed intake structure (refer to Drawing Nos. 33-100-6149 and -6150). The hole was advanced to a total depth of 46.2 feet.

The material consists of glacial ice-contact lakebed sediments (Qgi) (refer to Drawing No. 33- 100-6150). Nine standard penetration tests were performed in the material with blow counts ranging from 10 bpf to 50 blows for 0.4 feet of penetration. Laboratory classifications of the samples were primarily Silty Sand (SM) and Silty Sand with Gravel (SM)g. Groundwater was not encountered during drilling.

DH-13-14 is located near the middle section of the proposed intake structure (refer to Drawing Nos. 33-100-6149 and -6150). The hole was advanced to a total depth of 51.2 feet. The hole was terminated approximately 20 feet above the desired depth, due refusal, attributed to difficult drilling conditions using the hollow-stem augers. From ground surface to 39.7, feet the foundation material consists of glacial ice-contact lakebed sediments (Qgi). Two standard penetration tests were performed. Blow counts ranged from 5 bpf to 50 blows for 0.8 feet of penetration. Laboratory classifications of the samples were primarily Silty Sand with Gravel (SM)g with some Silty Gravel with Sand (GM)s. The remainder of the material in the boring consisted of glacial till (Qtg). Three standard penetration tests were performed with blow counts ranging from 41 to 64 bpf. Laboratory classifications of the samples were Poorly Graded Sand with Silt and Gravel (SP-SM)g and Poorly to Well-graded Gravel with Sand (GP)s to (GW)s. Groundwater was not encountered during drilling.

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The glacial ice-contact sediments (Qgi) form the foundation for the upstream portion of the multilevel intake structure. Excavation for the multilevel intake structure would need to be performed in a manner that would ensure that the glacial ice-contact lakebed sediments (Qgi) covering the glacial till are not penetrated in the reservoir basin. This layer is the primary water barrier holding the reservoir and penetration or damage to this layer could lead to unforeseen seepage problems downstream of the reservoir. Following is an excerpt from an undated construction documentation, “The inside slopes of the reservoir basin carried a natural cover of fine sediment practically impervious and from 25 to 40 feet thick. The upstream blanket of similar impervious material covered all exposed gravel to a substantial thickness and connected on each side with natural blanket, as mentioned above, and to the blue clay stratum in the river bed. No core wall was constructed. A cut-off trench was dug across the damsite” (Reclamation undated). Hence, care should be taken when penetrating the glacial ice-contact lakebed sediments to replace them or use suitable fine-grained material to backfill around any structure.

Helix (transition) Structure

The Helix Structure would provide a transition or drop structure between the intake and the downstream juvenile bypass conduit, designed with open channel flow through a gradually sloping helical conduit that would provide sufficient energy dissipation to protect the juvenile fish.

Three exploratory holes (DH-13-11, -12 and -13) were drilled to obtain samples and determine the properties of the subsurface materials (refer to Drawing Nos. 33-100-6149 and -6150). For a detailed description of overburden and foundation materials recovered from these drill holes, refer to the logs of exploration and sample photographs in Appendix B. Laboratory test results are included in Appendix C.

Testing and Sampling

DH-13-13 is located near the upstream end of the proposed helix structure (refer to Drawing Nos. 33-100-6149 and -6150). The hole was advanced to a total depth of 110.0 feet. From ground surface to 31.0 feet the material consists of glacial ice-contact lakebed sediments (Qgi).

Three standard penetration tests were performed with blow counts ranging from 36 to 48 bpf.

Laboratory classifications of the samples were Silty Sand with Gravel (SM)g and Silty Sand (SM). Glacial till (Qgt) was encountered from 31.1 to 71.1 feet. Four standard penetration tests were performed in the till with blow counts ranging from 33 bpf to 80 blows for 0.9 feet of penetration. Laboratory classifications of the samples were Silty Sand (SM), Sandy Silt s(ML) and Silt with Sand (ML)s. Glacial outwash (Qgo1) was encountered from 71.1 to the bottom of the hole at 110.0 feet. Four standard penetration tests were performed. Three of the tests met refusal in the initial 6-inch seating interval, one test resulted in 80 blows for 0.9 feet of penetration. Recovery was poor, but laboratory classifications of the one sample recovered was Well-graded Gravel with Sand (GW)s.

14 May 2014 – Cle Elum Dam Fish Passage Facilities Geologic Report

DH-13-12 is located near the middle of the proposed helix structure (refer to Drawing Nos. 33- 100-6149 and -6150). The hole was advanced to a total depth of 148.9 feet. From ground surface to 29.3 feet, the material consists of glacial ice-contact lakebed sediments (Qgi). Five standard penetration tests were performed with blow counts ranging from 14 to 53 bpf.

Laboratory classifications of the samples were Poorly Graded Gravel with Sand (GP)s and Silty Sand (SM). Glacial till (Qgt) was encountered from 29.3 to 82.8 feet. Nine standard penetration tests were performed with blow counts ranging from 34 bpf to 50 blows for 0.9 feet of penetration. Laboratory classifications of the samples were primarily Silty Sand with Gravel (SM)g with Silt (ML) and Poorly to Well-graded Sand (SP) to (SW) layers. Glacial outwash (Qgo1) was encountered from 82.8 to the bottom of the hole at 148.9 feet. Thirteen standard penetration tests were performed. One of the tests met refusal in the seating interval, the remaining were mostly around 100 blows for 0.3 to 0.9 feet of penetration. Laboratory classifications of the samples were primarily Well- to Poorly Graded Gravel with Silt and Sand (GW-GM)s to (GP-GM)s with Well to Poorly Graded Gravel (GW) to (GP). The water level measured in the observation well on November 5, 2013 was about 140.3 feet below the ground surface.

DH-13-11 is located near the downstream end of the proposed helical and at the upstream end of the proposed juvenile bypass conduit. The hole was advanced to a total depth of 148.7 feet.

From ground surface to 78.0 feet the overburden material consists of glacial till (Qgt). Twelve standard penetration tests were performed. One of the tests met refusal in the seating interval with results for the remaining SPT tests ranging from 28 bpf to 77 blows for 0.8 feet of penetration. Laboratory classifications of the samples reflected varied nature of the glacial till, ranging from Silt with Sand (ML)s to Well-graded Gravel with Sand (GW)s. Glacial outwash (Qgo1) was encountered from 78.0 to the bottom of the hole at 148.7 feet. Three standard penetration tests were performed in the upper portion of the unit with blow counts ranging from 80 blows for 0.7 feet of penetration to 100 blows for 0.2 feet of penetration. Laboratory classifications of the SPT samples were primarily Poorly Graded Gravel with Silt and Sand (GP-GM)s. Samples for gradation test of glacial outwash (Qgo1) from the lower portion of the unit were collected using a heavy-wall split-spoon drive sampler. A total of four drive samples were collected. Laboratory classification of the samples was primarily Poorly Graded Gravel with Sand (GP)s with some Well-graded Gravel with Sand (GW)s. The water level measured in the hole during drilling on July 28, 2013 was about 132.6 feet below the ground surface.

Juvenile Bypass Conduit

A seven-foot diameter (approximate) concrete conduit would carry passage flows from the upstream helix structure downstream along the right abutment side of the spillway chute and discharge to the spillway stilling basin. Construction of the bypass conduit would be performed using either tunneling or cut-and-cover methods. Two alignments have been delineated for each method: (1) a straight alignment for the tunnel option and (2) a slightly curved alignment of the cut-and-cover option. The geologic conditions are similar along both alignments.

May 2014 – Cle Elum Dam Fish Passage Facilities Geologic Report 15

Seven exploratory holes (DH-13-3 through -10) were drilled to obtain samples and determine the properties of the subsurface materials (refer to Drawing Nos. 33-100-6149 and -6150). For a detailed description of overburden and foundation materials recovered from these drill holes, refer to the logs of exploration and sample photographs in Appendix B. Laboratory test results are included in Appendix C.

Testing and Sampling

DH-13-10 is located near the upstream portion of the proposed juvenile bypass conduit along the tunnel alignment. The hole was advanced to a total depth of 124.3 feet. From ground surface to 68.0 feet, the material consists of glacial till (Qgt). Six standard penetration tests were performed with blow counts ranging from 33 bpf to 50 blows for 0.6 feet of penetration.

Laboratory classifications of the samples reflected varied nature of the glacial till, ranging from Sandy Silt s(ML) to Well- to Poorly Graded Gravel with Silt and Sand (GW-GM)s to (GP- GM)s. Glacial outwash (Qgo1) was encountered from 68.0 to the bottom of the hole at 124.3 feet. Seven standard penetration tests were performed in the outwash material. One of the tests met refusal in the seating interval, the remaining blow counts ranged from 50 blows for 0.5 feet of penetration to 130 blows for 0.3 feet of penetration. Laboratory classifications of the SPT samples were primarily Well- to Poorly Graded Gravel with Silt and Sand (GW-GM)s to (GP- GM)s. Groundwater was not encountered during drilling.

DH-13-9 is located along the cut and cover alignment of the proposed juvenile bypass conduit.

The hole was advanced to a total depth of 124.1 feet. From ground surface to 68.0 feet the material consists of glacial till (Qgt). Six standard penetration tests were performed with blow counts ranging from 15 bpf to 80 blows for 0.6 feet of penetration. Laboratory classifications of the samples reflected varied nature of the glacial till, ranging from Sandy Silt s(ML) to Well-graded Gravel with Silt and Sand (GW-GM)s. Glacial outwash (Qgo1) was encountered from

68.0 to the bottom of the hole at 124.1 feet. Six standard penetration tests were performed in the outwash material with blow counts ranging from 100 bpf to 100 blows for 0.6 feet of penetration. Laboratory classifications of the SPT samples were primarily Poorly Graded Gravel with Sand (GP)s to Poorly to Well-Graded Gravel with Silt and Sand (GP-GM)s to (GW-GM)s. The observation well was dry when measured on November 5, 2013.

DH-13-8 is located along the tunnel alignment of the proposed juvenile bypass conduit. The hole was advanced to a total depth of 129.5 feet. From ground surface to 68.6 feet, the material consists of glacial till (Qgt). Seven standard penetration tests were performed with blow counts ranging from 34 bpf to 80 blows for 0.2 feet of penetration. Laboratory classifications of the samples reflected varied nature of the glacial till, ranging from Silty Sand with Gravel (SM)g to Well- to Poorly Graded Gravel with Silt and Sand (GW-GM)s to (GP-GM)s and Well-graded Gravel (GW)s. Glacial outwash (Qgo1) was encountered from 68.6 to the bottom of the hole at

129.5 feet. Six standard penetration tests were performed in the material with blow counts ranging from 72 bpf to 100 blows for 0.4 feet of penetration. Laboratory classifications of the SPT samples ranged from Well-graded Gravel with Sand (GW)s and Poorly Graded Gravel

16 May 2014 – Cle Elum Dam Fish Passage Facilities Geologic Report with Sand (GP)s to Well-graded Gravel with Silt and Sand (GW-GM)s. The observation well was dry when measured on November 5, 2013.

DH-13-7 is located along the cut and cover alignment of the proposed juvenile bypass conduit.

The hole was advanced to a total depth of 118.7 feet. From ground surface to 28.2 feet, the material consists of glacial till (Qgt). Samples of the glacial till (Qgt) were collected for laboratory testing using a heavy-wall split-spoon drive sampler. Three drive samples were collected. Laboratory classification of the samples was primarily Poorly Graded Gravel with Silt and Sand (GP-GM)s. Glacial outwash (Qgo1) was encountered from 28.2 feet to the bottom of the hole at 118.7 feet. Samples of the glacial outwash (Qgo1) were collected for laboratory testing using a heavy-wall split-spoon drive sampler. Nine drive samples were collected. Laboratory classification of the samples was primarily Poorly Graded Gravel with Sand (GP)s. Samples from drill hole DH-13-7 were submitted to Reclamation’s MERL for corrosivity testing, see “Corrosivity and Concrete Aggregate Testing” section.

DH-13-6 is located along the tunnel alignment of the proposed juvenile bypass conduit. The hole was advanced to a total depth of 118.0 feet. From ground surface to 29.0 feet, the material consists of glacial till (Qgt). Three standard penetration tests were performed with blow counts ranging from 50 blows for 0.5 feet to 50 blows for 0.6 feet of penetration. Laboratory classifications of the samples reflected varied nature of the glacial till, ranging from Clayey Gravel with Sand (GC)s to Well Graded Sand with Silt and Gravel (SW-SM)g. Glacial outwash (Qgo1) was encountered from 29.0 to the bottom of the hole at 118.0 feet. Eight standard penetration tests were performed in the glacial outwash. One of the tests met refusal in the seating interval, the remaining blow counts ranged from 50 blows for 0.3 feet of penetration to 100 blows for 0.2 feet of penetration. Laboratory classifications of the SPT samples were primarily Well-graded Gravel with Sand (GW)s and Poorly Graded Gravel with Sand (GP)s. Groundwater was not encountered during drilling.

DH-13-5 is located along the tunnel alignment of the proposed juvenile bypass conduit. The hole was advanced to a total depth of 99.6 feet. From ground surface to the bottom of the hole, the material consists of glacial outwash (Qgo1). Ten standard penetration tests were performed with blow counts ranging from 100 bpf to 100 blows for 0.5 feet of penetration. Laboratory classifications of the samples were primarily Well-graded Gravel with Sand (GW)s.

Groundwater was not encountered during drilling.

DH-13-4 is located along the cut and cover alignment of the proposed juvenile bypass conduit.

The hole was advanced to a total depth of 108.4 feet. From ground surface to the bottom of the hole, the material consists of glacial outwash (Qgo1). Eight samples of the glacial outwash (Qgo1) were collected for laboratory testing using a heavy-wall split-spoon drive sampler. The samples from drill hole DH-13-4 were submitted to Reclamation’s MERL for corrosivity testing, see “Corrosivity and Concrete Aggregate Testing” section. The observation well was dry when measured on November 5, 2013.

May 2014 – Cle Elum Dam Fish Passage Facilities Geologic Report 17

DH-13-3 is located along the cut and cover alignment near the downstream end of the proposed juvenile bypass conduit. The hole was advanced to a total depth of 89.2 feet. From ground surface to the bottom of the hole, the material consists of glacial outwash (Qgo1). Nine standard penetration tests were performed. Five of the tests met refusal in the seating interval with blow counts for the remaining tests ranging from 50 bpf to 50 blows for 0.4 feet of penetration. Laboratory classifications of the samples ranged from Poorly to Well-graded Gravel with Silt and Sand (GP-GM)s to (GW-GM)s to Poorly to Well-graded Gravel with Sand (GP)s to (GW)s. The water level measured in the observation well on November 5, 2013 was about 80.2 feet below the ground surface.

Outlet Works Rehabilitation Construction Geology

Since originally constructed in 1933 the outlet works had experienced repeated problems related to deficiencies in the original design which included surging and pulsations during periods of high flow resulting in destruction of gate parts and steel liners and in cavitation at the gate portals. Frequent and expensive repairs and minor modifications were made. In 1973, a review of the maintenance report recommended that a study be undertaken to consider replacement of the existing cylinder gates, and replacing the original gooseneck outlet conduit with a straight tunnel section (refer to Drawing No. 33-D-4000). The feasibility design was completed in 1976 and specifications for the construction were released in 1978. The contract was awarded and work began in October 1978 and ended in October 1980 and the outlet works were operational by July 1980 (Reclamation 1982).

Due to the comparatively short length of the tunnel required for the project, an alternative mining method was proposed by the contractor. The sequence of construction consisted of the excavation (hand-mined) of lined stacked drifts and backfilling them with cement then excavating the replacement section of outlet tunnel (refer to Drawing 33-100-3394 and see Photograph 6).

The following sections summarize the geologic conditions documented during the rehabilitation of the outlet works and concentrates principally on the excavation of the replacement section of tunnel above the gooseneck. The site conditions encountered in this earlier work are pertinent to the design of the fish passage facilities, as similar conditions may be expected in the right abutment area of the dam.