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Home My WebLink AboutAPA374SUSITNA HYDROELECTRIC PROJECT WAT ANA DEVELOPMENT WINTER 1983 GEOTECHNICAL EXPLORATION PROGRAM VOLUME 1 MAIN REPORT SEPTEMBER 1983 .. SUS/TNA JO/NT VENTURE II-o-_ALASKA POWER AUTHORITY_-.-lI ( ..... - - SUSITNA HYDROELECTRIC PROJECT WATANA DEVELOPMENT WINTER 1983 GEOTECHNICAL EXPLORATION PROJECT VOLUME 1 MAIN REPORT Prepared for the ALASKA POWER AUTHORITY BY HARZA-EBASCO Susitna Joint Venture SEPTEMBER 1983 ARLIS Alaska Resources Library &Information Services Anchorage.Alaska ,- I TABLE OF CONTENTS J'IIIlRl - .... MAIN REPORT TABLE OF CONTENTS SECTION ACKNOWLEDGEMENTS 1.0 INTRODUCTION 1.1 PROJECT DESCRIPTION 1.2 SITE DESCRIPTION 1.3 PREVIOUS INVESTIGATIONS 2.0 PURPOSE AND SCOPE 2 .1 RIVER CHANNEL 2.2 RELICT CHANNEL 3.0 SUMMARY AND CONCLUSIONS 3.1 RIVER CHANNEL 3.2 RELICT CHANNEL 4.0 EXPLORATION METHODS PAGE 1-1 1-1 1-2 1-2 2-1 2-1 2-2 3-1 3-1 3-2 4-1 ,...,. 4.1 GEOPHYSICAL EXPLORATION Ground Penetrating Radar Seismic Refraction Borehole Gamma Logs 4-1 4-1 4-1 4-2 4.2 DRILLING AND SAMPLING 4.3 IN-SITU PERMEABILITY AND PRESSURE TESTING 4.4 LABORATORY TESTING 4.5 RELICT CHANNEL INSTRUMENTATION 4.6 PERMITS AND ENVIRONMENTAL PROTECTION 5.0 RIVER CHANNEL INVESTIGATIONS 5.1 OVERBURDEN -ALLUVIUM 4-2 4-3 4-4 4-5 4-5 5-1 5-1 5.1.1 5.1.2 Surface Morphology and Thickness Classification and Distribution 5-1 5-2 5.1.3 Permeability 5.1.2.1 5.1.2.2 5.1.2.3 5.1.2.4 Gravel (GW) Sandy Gravel (GW-GM) Gravelly Sand (SP-SW Sand (SP-SM) ARLIS 5-3 5-4 5-4 5-5 5-6 Alaska Resources Jibrary &Information services Anchorage,Alaska i SECTION PAGE - 5.2 BEDROCK 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 Channel Configuration Lithology Structure Weathering and Alteration Zones Pressure Testing 5-7 5-7 5-8 5-8 5-10 5-10 """, 5.3 FOUNDATION CONDITIONS 5.3.1 Main Dam 5-11 5-11 -5.3.1.1 5.3.1.2 5.1.3.3 Main Dam Centerline Upstream Area Downstream Area 5-11 5-13 5-14 5.3.2 5.3.3 5.3.4 Upstream Cofferdam Downstream Cofferdam Diversion Tunnel Portals 5-16 5-17 5-19 - 5.3.4.1 5.3.4.2 Upstream Portal Downstream Portal 5-19 5-20 6.0 RELICT CHANNEL INVESTIGATIONS 6.1 CLASSIFICATION SYSTEM 6-1 6-1 6 .1.1 6.1.2 Relict Channel Morphology Bedrock Exploration and Lithology 6-1 6-2 6.2 OVERBURDEN STRATIGRAPHY 6-3 6.3 OVERBURDEN PHYSICAL PROPERTIES 6.2.1 6.2.2 6.2.3 6.3.1 6.3.2 6.3.3 6.3.4 Classification Criteria Stratigraphic Units Stratigraphic Correlation Soil Types Texture and Plasticity Density Permeability 6-4 6-5 6-9 6-11 6-11 6-12 6-14 6-15 - 6.4 GROUNDWATER 6.5 PERMAFROST 6 .6 REF'~~NCES 6-17 6-18 R-1 - - ..... L1ST OF TABLE S TABLE NO . 4-1 RIVER CHANNEL,SUBSURFACE GEOPHYSICAL PROFILES, FOOTAGE SUMMARY 4-2 RIVER CHANNEL,BOREHOLE GEOPHYSICAL LOGGING,FOOTAGE SUMMARY 4-3 RELICT CHANNEL,BOREHOLE GEOPHYSICAL LOGGING,FOOTAGE SUMMARY ~, - ..... 4-4 4-5 4-6 RIVER CHANNEL,1983 WINTER DRILLING PROGRAM,DATA SUMMARY RELICT CHANNELS,1983 WINTER DRILLING PROGRAM,DATA SUMMARY SUMMARY OF 1983 WINTER PROGRAM LABORATORY TESTING,NUMBER OF SAMPLES AND TEST TYPE 4-7 RIVER CHANNEL,SUMMARY OF 1983 WINTER PROGRAM LABORATORY TESTING,NUMBER OF SAMPLES AND SPECIFIC TESTS 4-8 4-9 RELICT CHANNEL,SUMMARY OF 1983 WINTER PROGRAM LABORATORY TESTING,NUMBER OF SAMPLES AND SPECIFIC TESTS RELICT CHANNEL,SUMMARY OF INSTRUMENTATION INSTALLATION,TYPE,DEPTHS,AND ELEVATIONS 5-1 RIVER CHANNEL -SUMMARY OF MATERIAL CLASSIFICATIONS , 5-2 RIVER CHANNEL -·IN-SlTU OVERBURDEN PERMEABILITY TEST RESULTS 5-3 RIVER CHANNEL -BEDROCK PRESSURE TEST RESULTS 6-1 WATANA RELICT CHANNEL STRATIGRAPHY, GENERALIZED DESCRIPTION OF PROPERTIES -6-2 RELICT CHANNEL,DEPTHS TO TOP OF INTERPRETED STRATIGRAPHIC UNITS 6-3 RELICT CHANNEL,SUMMARY OF MATERIAL CLASSIFICATIONS BY UNITS iii FIGURE NO.TITLE LIST OF FIGURES - - - 1-1 WATANA DEVELOPMENT,PROJECT PLAN AND LOCATION MAP 1-2 WATANA DEVELOPMENT,SITE PLAN AND VICINITY MAP 5-1 DAM SITE AREA -EXPLORATION PLAN - 5-2 RIVER CHANNEL,OVERBURDEN CONTOUR MAPS 5-3 RIVER CHANNEL,FOUNDATIONS MATERIALS, GRADATION SUMMARY 5-7 RIVER CHANNEL,FOUNDATION SANDS,GRADATION SUMMARY 5-5 RIVER CHANNEL,FOUNDATION SANDY GRAVELS, GRADATION SUMMARY 5-4 5-6 RIVER CHANNEL,FOUNDATION GRAVELS, GRADATION SUMMARY RIVER CHANNEL,FOUNDATION GRAVELLY SANDS, GRADATION SUMMARY - -5-8 RIVER CHANNEL DAMSITE AREA,CONTOUR MAP, TOP OF BEDROCK 5-9 RIVER CHANNEL,DAM AXIS FOUNDATION AREA, GEOLOGIC PROFILE B-B 5-10 RIVER CHANNEL,DAM AXIS FOUNDATION AREA, GRADATION SUMMARY - 5-11 RIVER CHANNEL,MISCELLANEOUS BORINGS 5-12 RIVER CHANNEL,AREA UPSTREAM OF DAM AXIS, GRADATION SUMMARY 5-13 RIVER CHANNEL,AREA DOWNSTREAM OF DAM AXIS, SANDY GRAVEL GRADATION - ! 1 ACKNOWLEDGMENTS ACKNOWLEDGEMENTS The Harza-Ebasco Joint Venture wishes to acknowledge the advice and guidance provided by their geotechnical consultants R.B.Peck and A. J.Hendron.The planning of the winter exploration program was guided by their recommendations and suggestions which have been utilized during the preparation,of this report. The Buffalo and Anchorage offices of Acres American Inc.,contributed to a smooth and orderly trans it ion.Their cooperat ion in providing access to records and,data,assistance in subcontract transfers,and opinions on interpretation is gratefully acknowledged. Har za-Ebasco also wishes to acknowledge the guidance and support pro- vided by Alaska Power Authority and its staff. 1 - ~- 1.0 INTRODUCTION 1.1 PRO,JECT DESCRIPTION 1.2 SITE DESCRIPTION 1.3 PREVIOUS INVESTIGATIONS - - - 1.0 INTRODUCTION The work described in this report was completed by the Harza-Ebasco Susitna Joint Venture under contract to the Alaska Power Authority. 1.1 PROJECT DESCRIPTION The Susitna Hydroelectric Project consists of the Watana and Devil Canyon developments and 1S located 1n the Upper Susitna River Basin of South-Central Alaska,approximately midway between Anchorage and Fairbanks (Figure 1-1).The Watana Damsite,which this report addresses,is the upstream development,and is located on the Susitna River at about river mile 184,between two small tributaries,Tsusena and Deadman Creeks. The conceptual Watana project plan as depicted 1n the Federal Energy Regulatory Commission license application and used to guide the explor- ation program,consists of an 885 foot high embankment dam impounding a reserV01r more than 40 miles long.The dam is roughly 4,000 feet long at the crest,narrowing to 400 feet at the river bottom (Figure 1-2). The base width of the dam exceeds 3,900 feet.Spillway and power intake structures would be located immediately upstream of the dam, with an underground powerstation located downstream of the dam in the right bank.Construction of the dam will require upstream and downstream cofferdams and the excavation of two diversion tunnels.The materials required for construction of the cofferdams and ma1n dam will be acquired from borrow or quarry areas in proximity to the site and from required excavation to the extent possible. 1-1 1.2 SITE DESCRIPTION The Watana Damsite is located within a V-shaped canyon incised into a broad,glaciated upland plateau.The canyon ~s over 900 feet deep at the damsite,and more than one mile wide at the top.The lower por- "'~! tions of the canyon consist of steep slopes,while the upper port ions flatten becoming more gentle near the top.During the summer,the Susitna River flows are high,filling the river channel to a width of 400 feet.During the winter,the flow is reduced,and extensive gravel bars are exposed in the valley bottom.The bedrock in the area con- sists of Tertiary igneous rocks,chiefly diorite and andesite. The area has undergone several geologically recent periods of glacia- tion with attendant erosion and deposition.The Watana relict channel area,northeast of the site,consists of one main channel and other - secondary tributary channels.The channels are filled with fluvio- glacial,and related lacustrine deposits. 1.3 PREVIOUS INVESTIGATIONS The Susitna Project Damsites (Figure 1-2)at Watana and Devil Canyon were investigated intermittently betwen 1952 and 1979 by the U.S. Bureau of Reclamat ion and the U.S.Army Corps of Engineers.At the Watana site,these investigations consisted of geologic mapping, se~sm~c refraction surveys,and several boreholes within the r~ver channel,abutments,and the surrounding area.A total of six potential borrow and quarry sites were identified.Four of the borrow sites were explored with test pits and auger borings.The Corps of Engineers also installed ten stand-pipe piezometers and thirteen thermal probe stand- pipes in boreholes. 1-2 ""'" - - - ..... - From 1980 to 1982,the Alaska Power Authority commissioned Acres American,Inc.to conduct more extensive studies at both sites.These studies at the Watana site,aimed at developing the feasibility of the hydroelectric project,further identified and characterized the geologic conditions of the dam abutments,the potent ial borrow and quarry areas,and the relict channels.The results of these studies, presented in the 1980-81 Geotechnical Report and the 1982 Supplement, concluded that there was nothing to impair the technical feasibility of the Watana Project. 1-3 r ~~ f 2.0 PURPOSE AND SCOPE 2.1 RIVER CHANNEL 2.2 RELICT CHANNEL - - _. - 2.0 PURPOSE AND SCOPE The purpose of this report 1S to present the results obtained during the Winter 1983 Explorations Program which will be used for the geotechnical design of the Watana Dam Project.The report is comprised of two volumes.Volume 1,Main Report,summar1zes the results of the explorat ion program.Volume 2,Appendices,contains detail s of the geophysical exploration methods,drilling and sampling methods, borehole logs and laboratory test results. Discussed herein are geological conditions 1n the ma1n river valley at the damsite,cofferdams and in the adjacent relict channel.Emphasis 1S g1ven to geophysical exploration,drilling and sampling,field permeability testing in overburden and pressure testing in bedrock, laboratory testing and instrumentation. The exploration program was executed during January-April,1983.The Harza-Ebasco Susitna Joint Venture,carried out this program under interim contracts with the Alaska Power Authority,and the participa- tion by Acres American during a transition period which ended in mid- February.Subcontracted technical and logistical support was provided by Denali Drilling,Inc.,Harding-Lawson Associates,R&M Consultants, Air Logistics,Inc.,Alyeska Air Service,and Cook Inlet Region, Incorporated. 2.1 RIVER CHANNEL In general the exploration program in the r1ver channel was designed to delineate subsurface conditions at selected project features including the upstream and downstream cofferdams,the dam axis,and the diversion 2-1 A..LASKA RE~OUPCES LTRRARlJ U.S.DEPT.OF :::~'~'-"R tunnel portals.The exploration program was designed to: o determine the distribution and physical properties of the channel deposits. o to assess the suitability of the channel deposits as a foundation for the main dam. o o to provide data for cofferdam design. to estimate the potential quantities of material to be excavated in the dam foundation o to determine the characteristics of the underlying bedrock for assessing dam foundation suitability and treatment. The program was implemented by reviewing previous work.performing further geophysical surveys and by drilling boreholes using both hammer and rotary equipment.Geophysical surveys.using ground penetrat ing radar.se~sm~c refraction.and downhole gamma logging,were designed to locate the top of the alluvium and bedrock.to identify bedrock surface anomalies.and to aid in stratigraphic correlations. 2.2 REL leT CHANNEL The relict channel exploration program was designed to supplement pre- vious work by further characterizing the litho log}'and stratigraphy of the Watana relict channels.The overall purpose of the investigation was to provide further assessment of the geohydrologic propert ies of the Watana reI ict channel area and to supplement prel iminary data on liquefaction potential of the glacial and fluvial deposits.Assessment of the channel deposits was made by boreholes,geophysical monitoring and installation of piezometers. 2-2 -. - - r l r- I ( t r i ) r, 3.0 SUMMARY AND CONCLUSIONS 3.1 RIVER CHANNEL, 3.2 RELICT CHAN N EL - 3.0 SUMMARY AND CONCLUSIONS 3.1 RIVER CHANNEL The river channel exploration program provided new information regarding the channel deposits and bedrock relative to the dam foundation.The following conclusions and observations have been drawn from the exploration data: *The bedrock channel 1S generally symmetrical the nver centerline.The channel bottom 1S exception of two pronounced depressions 1n the axis and upstream toe. in cros s-sect ion about nearly flat with the area between the dam - - ""'"' ...., *The bedrock underlying the r1ver channel alluvium ranges from altered to fresh,hard,diorite.Areas of moderately to closely fractured rock were found as were a few shear zones containing fine-grained gouge material.Water takes from pressure test ing within these zones were low. *Although sections of closely spaced fractures were found within the bedrock,pressure testing indicated low water losses. *Alluvial deposits overlying the bedrock channel are typically less than 80 feet thick,although two bedrock depressions upstream of center line contain deposits over 140 feet thick . *The deposits within the r1ver channel are coarse-grained gravels,sandy gravels,and materials are generally well-graded. 3-1 comprised primarily of gravelly sands.These *The distribution of the overburden materials within the river chan- nel is related to the geometry and characteristics of the river flow, with the locat ions of ident ifiable buried gravel bars and boulder and cobble concentrations related to flow energy gradients. *Permeability of the r1ver deposits 1S variable. grain S1ze and drilling operations indicate the materials are very pervious. Evaluations of majority of the - *Downhole gamma logs of the river boreholes,1n general,reflect the lack of continuous clay layers in the river alluvium.Further,local high gamma counts 1n the channel deposits appear to coincide with accumulations of boulders which yield gamma signatures similar to fresh unweathered diorite. 3.2 RELICT CHANNEL The results of the winter exploration program of the relict channel generally support and correlate with previous results and interpreta- tions of geologic conditions in the relict channel area.No major var1ances 1n subsurface conditions from those previous exploration results were obtained 1n these relict channel explorations.The following conclusions are made relative to subsurface conditions explored. * * The borings along se1sm1C Survey Line SW-3 confirm the exis- tence of the two bedrock channel thalwegs delineated from refraction survey interpretation.The borings partially define the cross-section of the channels and provide new data on the strat igraphy and material propert ies of deep outwash and alluvium deposits. The borings along se1sm1C Survey Line DM-A define the surface of the compact,Unit GIG r till and lacustrine deposits. 3-2 - ,~ - - ,- * * * The density of Unit ElF outwash deposits and overlying units varies from medium dense to very dense beneath the act ive or seasonal frost zone,which ~s of about 15 feet below the ground surface.Unit GIG'lacustrine and till deposits and all underlying units are generally dense to very dense. Portions of the permeable outwash and alluvium deposits are not saturated.Groundwater is present in local areas of out- wash and alluvium deposits,generally above till and lacustrine aquicludes and possibly where horizontal groundwater movement ~s retarded by the presence of permafrost or the surface of the underlying aquiclude. Surface infiltration into glacial deposits below Unit GIG'~s retarded over much of the area by the lower permeability of Unit GIG'. The entrance and exit conditions for potential seepage flow through outwash and alluvium Units H,I and K are poorly defined.Future shallow explorations by seismic refraction, trenching,test pitting,augering,and possibly by aditing should be conducted at these areas.In addition,the planned deep pumping tests in Unit K material,at and near the "bottleneck"in the deep channel in the center of the relict channel area,should be carried forward if any uncertainty about the through-going nature of Unit K remains after near-- surface investigations are completed. 3-3 4.0 EXPLORATION METHODS 4.1 GEOPHYSICAL EXPLORATION 4.2 DRILLING AND SAMPLING 4.3 PERMEABILITY TESTING 4.4 LABORATORY TESTING 4.5 INSTRUMENTATION 4.6 PERMITS AND ENVIRONMENTAL PROTECTION - - - 4.0 EXPLORATION METHODS 4.1 GEOPHYSICAL EXPLORATION The winter exploration program utilized three geophysical investigation methods,the details of which are described below. Ground Penetrating Radar The ground penetrat ing radar was used as a rapid reconna1sance tool to locate areas of shallow bedrock,to determine the thickness of river ice,and to locate the top of river alluvium.The system produced a continuous profile of near surface materials.Fourteen radar profiles were run for a total coverage of 8,490 lineal feet as shown on Table 4-1. Seismic Refraction The results of seismic refraction surveys were incorporated into the bedrock drilling program by providing indications on the depth to bedrock throughout the river channel.Since the higher velocity ice layer masked the underlying lower velocity alluvium,the offset between the shot and geophone spread had to be long enough to detect the first arrival signals from the bedrock.Consequently,refraction profiles were run parallel or oblique to the river channel to take advantage of the long offset.Ten reversed refraction lines were run;totaling 8,785 lineal feet of geophone coverage as shown in Table 4-1. Borehole Gamma Logs The borehole gamma logs ass isted 1n strat igraphic correlat ion of the r1ver channel deposits and the glacial/fluvial deposits in the relict 4-1 channels.Natural gamma logs were run in 22 r~ver channel boreholes as shown in Table 4-2 and tn 8 relict channel holes as shown ~n Table 4-3. Details of the geophysical exploration program,tables,figures,and gamma logs are presented in Volume 2,Appendix A. 4.2 DRILLING AND SAMPLING The damsite exploration drilling program,performed along and adjacent to the river channel is shown on Figure 5-1;exploration in the relict channel area is shown on Figure 6-1. A hammer drill rig,Becker Model AP-1000,us~ng a percussive hammer, drilled most of the boreholes,switching to a rotary attachment with roller cone drill bits when drilling conditions became difficult at depth.The percussive hammer system used a diesel pile hammer to drive a 5-l/2-inch or 9-inch a.D.double-wall pipe while a reverse air circulation system removed the cuttings as the pipe advanced.The sample cuttings were recovered from an energy dissipating cyclone. Specially designed tooth bits were used to penetrate the soil formations and to direct the soil into the inner pipe.A diamond drill rotary head was used with an NX-size core barrel to core ins ide the drive pipe whenever bedrock or refusal was encountered. A geologist or geotechnical engineer continuously monitored the drill- ing operations.Usually at five foot intervals,a composite sample was collected,logged,and placed in a canvas bag for transportation to the ..... ~I ..... "'"" field laboratory.Samples for moisture determinat ion were sealed In plastic bags.A split-spoon drive sampler was passed inside the drive pipe as necessary to recover intermittent samples. 4-2 Blow counts for - ...... -- ....., ..... driving the split spoon sampler were taken for estimating relative densities. Blow counts recorded during driving of the double-wall drive pipe were used only as a relative indication of density.The energy delivered by the diesel hammer was not always constant because the driller adjusted the fuel injection to control p~pe penetration rate.Also,the resist- ance to penetration,due to pipe wall skin friction,increased with depth thereby absorbing an increasing amount of the hammer I s energy. Fourteen boreholes were dri lled in the reI ict channel area for a tot al of 1,927 lineal feet plus a boring for a potential water well boring WW-3 as shown in Table 4-4.A total of 43 borings were drilled in the river channel for a total of 3710 lineal feet including five 45-degree angle holes as shown in Table 4-5.A lightweight rotary core drill rig with an NX-size Gore barrel was mobilized late in the program for the river areas where ice conditions prohibited the use of the heavier hammer drill rig. A detailed discussion of the drilling and sampling methods can be found in Volume 2,Appendix B. 4.3 IN SITU PERMEABILITY AND PRESSURE TESTING Constant head tests and hydraulic pressure tests (using a mechanical packer)were conducted in the r~ver channel boreholes to determine information in regard to the overburden permeability and potential for water loss in the bedrock . During the performance of constant head tests ~n the r~ver overburden, water was added to the open drive pipe at a rate sufficient to maintain a constant water level at or near the top of the pipe for a period of 4-3 not less than 10 minutes.The pes it i ve disp lacement pi s ton beam pump on the drill rig had a capacity limited to 18 gpm.Therefore,onl y sections of alluvium anticipated to have the lowest permeability were tested.Ten constant head tests were conducted in six boreholes. For the performance of hydraulic pressure tests in the bedrock,19-foot intervals of the borehole were isolated using mechanical packers.For each test interval,water was injected in steps by increasing and decreasing pressures,and flow rates were measured at each pressure increment. boreholes. Nine hydraulic pressure tests were conducted 1n four ~, The.formulas used to compute the approximate coefficient of permea- bility for both the constant head tests and hydraulic pressure tests are from The Earth Manual,U.S.Bureau of Reclamation (1974). 4.4 LABORATORY TESTING As part of the Winter 1983 Field Drilling Program a field soils laboratory was established and operated at the Watana site The various types of soil encountered 1n the r1ver and relict channels were classified 1n accordance with the Unified Soil Classification System and tested in accordance with the following ASTM Procedures: a)Particle Size Analysis ASTMD 422-62 (modified) b)Atterberg Limits ASTM D 423-66,AS1M D 424-59 c)Moisture Content ASTM D 7126-71 d)Organic Content Standard Method e)Specific Gravity ASTM D 854-58 4-4 ..." - r f) g) Compaction Visual Classification ASTM D 698,ASTM D 1557-78 ASTM D 2488-69 - ~ I .-. .... .... During the winter program,a total of 1,421 index property tests were performed on 838 samples.The types and quantities of tests performed during the winter program are tabulated ~n Tables 4-6 through 4-8, inclusive.The results of these tests are surrnnarized on the test summary forms presented in Volume 2,Appendix D 4.5 RELICT CHANNEL INSTRUMENTATION Piezometers and thermal probes were installed l.n selected boreholes to monitor the groundwater and thermal regimes in the overburden depos its in the relict channel areas as indicated l.n Table 4-9.Pneumatic piezometers were chosen for installation to allow groundwater monitor- ing during freezing conditions which exist at the site area during much of the year.To facilitate monitoring the thermal regime of the materials,1 or 2-inch LD.capped PVC pipes filled with ethylene glycol were installed.Readings are taken at five foot intervals using a portable thermistor cable,lowered into the PVC pl.pe.Both the p~ezometers and thermal probes are scheduled to be read bi-monthly . 4.6 PERMITS AND ENVIRONMENTAL PROTECTION The winter geotechnical program was conducted with land use authoriza- tions and permits obtained before and during the program.Permit stipulations and control of exploration activities resulted l.n the pro- gram being executed with minimal damage to the environment. U.S.Bureau of Land Management (BLM)temporary use permit number AA44409 and Alaska Department of Natural Resources (ADNR)land use per- 4-5 mit number LVP SCM 82-036 were obtained to mobilize and demobilize drilling and support equipment to and from the Watana site over a w~n ter access trail across federal and state lands.This was the same trail used by the Corps of Engineers in 1978,and by the Alaska Power Authority in 1980.Permit stipulations were complied with during the mobilization ~n January,and the demobilization ~n April.BLM representatives observed a portion of the mobilization,provided authorization to use the trail for demobilization,and observed the demobilization. Other land use permits and authorizations consisted of BLM permit num- ber AK0170096 for conduct ing field explorat ions on federal lands;an agreement between the APA,Cook Inlet Village Corporations 'and CIRI for activities on lands conveyed and managed by these native organizations; and letter of non-objection from CIRI,Knikatna,Inc.,Tyonek Native Corporation,Inc.,and the State of Alaska for land access and explora- tion activities on lands selected by these agencies but managed by BLM. A letter of non-objection for construction and use of an access trail from Watana Field Camp to the Susitna River channel was obtained from Knikatna,Inc. Other types of permits obtained were a temporary water use permit from the ADNR for pumping water from test wells or surface waters.Archaeo- logical clearances of borehole locations were obtained from a Univer- sity of Alaska archaeologist acting for the ADNR.Authorizations were obtained from the ADNR and BLM for use of Miller Lake as a temporary ice airstrip. Restorat ion work was int iated at the access trail from Watana Field Camp to the Susitna River channel.Terracing and grading of the trail was performed at several locations to assure that erosion of the tundra did not occur during spring break-up and carry sediment into the river. 4-6 """'I - 5.0 RIVER CHANNEL~INVESTIGATIONS 5.1 OVERBURDEN (Alluvium) 5_1.1 Surface Morphology and Thickness 5.1.2 Classification and Distribution 5.1.3 Permeability 5.2 BEDROCK 5.2.1 Channel Configuration 5.2.2 Lithology 5.2.3 Structure 5.2.4 Weathering and Alteration Zones 5.2.5 Pressure Testing 5.3 FOUNDATION CONDITIONS 5.3.t Main Dam 5.3.2 Upstream Cofferdam 5.3.3 Downstream Cofferdam 5.3.4 Portals 5.4 CONCLUSIONS AND RECOMMENDATIONS r I I I r I -'I 5.0 RIVER CHANNEL INVESTIGATIONS Discussion of the ,findings and results of the r1ver channel exploration program are presented below.The work area extends from the upstream diversion tunnel portals to the downstream outlets,a distance of approximately 6,000 feet as shown 1n Figure 5-1.Within this area, geophysical and drilling explorations were conducted to develop topo- graphic information,characterize overburden depths and physical characteristics,and establish the depth to bedrock and the bedrock properties.Also determined were permeability and pressure test 1n- formation in overburden and bedrock respectively.The discussion below is divided into the following sections:overburden and bedrock sub- surface conditions at the cofferdams,main dam,and diversion tunnel portal areas . 5.1 OVERBURDEN (ALLUVIUM) 5.1.1 Surface Morphology and Thickness The distribution of gravel bars along the edge of the Susitna River was mapped prior to the winter exploration program.This data was combined with ground penetrating radar profiles and borehole results to develop a topographic map of the surface of the r1ver bottom presented as Figure 5-2.Topographic relief is nominally 10 feet,but locally exceeds 20 feet in the area of the upstream cofferdam.Over most of this stretch of river,the stream bed gradient is relatively flat. The thickness of the overburden deposits within the r1ver channel ranges to over 140 feet as shown on Figure 5-2.Along the centerlines of the menn dam and cofferdams,the overburden reaches a average thickness of 80 feet.The alluvial deposits are thickest within the 5-1 two bedrock depressions located approximately 900 and 1,900 feet upstream of the main dam centerline. 5.1.2 Classification and Distribution A wide range of soil types and mixtures exist in the r1ver channel. The results of the drilling and sampling program indicate that the river alluvium is mostly sandy gravels,with materials ranging from cobbles and boulders to small amounts of sand.The finer-grained materials were found to be a part of the matrix of the coarser materials rather than being a distinct layer or lense. The coarseness of the r1ver channel materials was evidenced on several occasions by deflection of the drive pipe.Coring beneath the refusal point of the drive pipe frequent ly revealed the presence of boulders which were estimated to range in diameter from less than 1 foot to over 5 feet.An isolated pocket of clay-rich peat was found 1n one angle- hole (HD83-46)drilled into the left bank,main darn centerline. The lithology of the gravels sampled 1n the r1ver channel include diorite,andes ite,gneiss,granodiorite,argillite,and minor amount s of granite.Cobbles,gravel,and sand particles are generally sub- round to round,with the larger part ic les having smooth,unweathered surfaces. Laboratory analyses of the hammer drill samples indicate that there are generally four types of material in the river channel.Table 5-1 sum- marizes the percentage distribut ion and gradat ion of each of the four major types.Almost 67%of the materials sampled 1n the river channel are classified as well-graded sandy gravel,with about 21%classified as poorly-graded gravelly sand.About 10%of the materials are classi- fied as well-graded gravel,and less than 2%are poorly-graded sands. 5-2 '""'I .., ~I - ..... .... ..... Figure 5-3 presents a summary of the grain size distributions for the four primary materials.Note that the apparent convergence of the gra- vel,sandy gravel,and gravelly sand curves near the 3-inch size range reflects the nze limitation of the drilling and sampling equipment, and does not represent the coarsest fraction of the in-situ materials. Further the coarser fractions of the gradations are subject to additional intrepretation as the hammering action of the drill bit fractured a certain amount of the coarse gravel,cobbles,and boulders. The·percentage of the total sample represented by broken fragment s retained on the 3/4-inch sieve was recorded as part of the classification as noted on the table.Fine fraction material occurs ~n samples of all four primary materials,but rarely exceeds 10%of the total sample.Details of the distribution and characteristics of each of these primary material types is presented below. 5.1.2.1 Gravel (GW) The gravel deposits show a remarkable similarity throughout the dam foundation area.Figure 5-4 presents the weighted average and upper and lower limits of the gradat ion based on 21 samples represent ing 76 feet of sampled interval.An average of 37'%of the sampled materials on the 3/4 s~eve are broken fragments,indicating that the in-situ material contains an abundance of coarser material not properly re- flected in the sample. As expected,the gravel materials encountered are located on or near the large gravel bars.These bars are on the inside part of curves ~n the r~ver channel,and represent deposition on the low-velocity side of the channel during periods of high flow.The gravel layers occur primarily in the top 30 to 40 feet. 5-3 Downhole gamma logging of borings were completed for most of the river channel holes.Gamma logging of the bedrock port ions of the borings indicate that fresh,unaltered diorite yields the highest of the primary recorded gamma counts.Within the r~ver channel fill materials,the exposed and buried gravel bars and the deposits mantling the channel bot tom also yield similarly high gamma counts,perhaps reflecting the abundance of fresh diorite cobbles and boulders. 5.1.2.2 Sandy Gravel (GW-GM) Figure 5-5 presents the high and low range,and average gradat ion curves for this material,based on 150 samples covering 524 feet of sampled interval.The materials are generally well-graded,although some of the medium sand fraction is missing.The mean grain size of these material s is fine to coarse gravel.The upper limit of part ic Ie size,shown as roughly 3 inches,represents limitations of the drilling and sampling techniques.On the average,20%of the material retained on the 3/4"sieve sampled consisted of broken fragments of larger particles,indicating that the in-situ materials are somewhat coarser than the laboratory data indicate. The sandy gravel material s represent typical lent icular r~ver channel sediment deposits.Variations in grain size and gradation are noted, with concentrations of large cobbles distributed as pockets and limited strata. 5-4 ~I r I - - The downhole gamma logs of these materials are characterized by variations in emission levels over vertical distances ranging from several inches to over one foot.Although these variations may reflect stratification or bedding of the deposits,it 1S also possible that the gamma peaks 1n part reflect distribution of fresh diorite cobbles and boulders. 5.1.2.3 Gravelly Sand (SP-SW) Figure 5-6 presents the high and low ranges,and average gradat ion curves based on 50 samples representing 166 feet of sampled interval. The median grain size of the sampled material s is a medium to coarse sand,and the material is poorly-graded.Some of the samples are skip-graded,with much of the medium sand-sized fract ion missing.An average of 11.5%of the material retained on the 3/411 sieve consisted of broken fragments. The gravelly sand materials seem to occur primarily within the central part of the channel,or along the outside section of the major curves 10 the nver.This distribution is consistent with the observed course of the river during low-flow periods.Since these material s represent deposition during low-flow periods,they ltmeanderlt within the coarser river channel deposits.The meandering pattern results in extens ive inter-fingering with the coarser deposits formed during the periods of high flow. The downhole gamma signature of the gravelly sands 1S in general less intense than those of the gravels or sandy gravels. 5-5 5.1.2.4 Sand (SP-8M) The sand materials compr~se less than 2%of the total material sampled. Figure 5-7 presents the high and low range,and average gradation curves for the material,based on 6 samples represent ing 10 feet of sampled interval.Most of the samples are classified as fine sands, and are poorly graded.Less than 4%of the material sampled contains broken fragments,indicating that the laboratory results are comparable to the gradation of the in-situ materials. The sands occur within all of the coarser units,and probably represent deposition in very local,quiet water conditions,such as eddies and overbank ponds.Their minor quant ity,thickness,and random distri- bution within the river channel precludes their consideration as an important part of the river channel stratigraphy. The downhole gamma logs of these sand units ~s typified by very low counts. 5.1.3 Permeability Constant head permeability tests were completed within the finer grained,less permeab Ie units in the river channel.Test ing of the more pervious gravels and sandy gravels was not possible due to limita- t ions of the equipment.The results 6f the tests are presented on Table 5-2.The range of permeability values obtained (1.2xlO-l to 5-6 1.5xlO-3 em/sec)are considered to be 1n the low range even for the finer materials tested. In addition to the constant head tests,field observations during the drilling operat ion provided additional insight as to relative permeabilities.During the progress of the hammer drilling,it was evident that some intervals were much more permeable than others. While all the river channel deposits were saturated,penetration of some sands and gravels was accompanied by noticeably greater quantities of return water from the reverse air circulation system.For example, 1""'" I 1n borehole HD83-l2 at the main dam centerline,large quantities of water were reported for virtually the entire 70 feet of alluvium. Borehole HD83-l0,also along the main dam centerline,reported high water returns coincident with a gravel layer,then reduced water return after pass1ng through the gravel.At borehole HD83-37,about 800 feet upstream of the main dam centerline,several discrete,1 to 5-foot intervals of high permeability material were reported 1n the top 100 feet of·the boring based upon water returns. These observations coupled with the test data indicate that the allu- will vary greatly over short lateral and vertical distances due to the lenticularity of the alluvium.- v1um in the river channel 1S generally very pervious.Permeabi 1i ty 5.2 BEDROCK 5.2.1 Channel Configuration The configuration of the bedrock channel was investigated uS1ng a com- bination of seismic refraction surveys and borehole data.A topo- _. I - graphic map of the top of the bedrock surface is shown on Figure 5-8. Bedrock elevations beneath the r1ver bed range from 1,450 to 1,310 5-7 feet.The sidewall slopes of the buried bedrock channel are similar to those of the exposed canyon walls in most areas. The base of the bedrock channel ranges 1n width from about 100 to over 300 feet.With the exception of two isolated bedrock depressions,the bedrock surface along the axis of the river is near level,with a drop of less than 20 feet over the 6,000 feet of river run between the up- stream and downstream portal locations. Two apparently isolated bedrock depressions occur about 900 and 1,900 feet upstream of the main dam centerline as seen in Figure 5-8.These low areas were first indicated by the seismic refraction work and were later verified by drilling.Overburden depths in these two depressions are 50 to 70 feet greater than the average channel bottom.Although their origin is unknown,it 1S likely the depressions result either from erOS10n during very high flows of the r1ver or differential erosion of a shear or fracture zone which crosses the river. 5.2.2 Lithology Bedrock encountered beneath the channel overburden 1S predominantly fine to medium-grained diorite,with some monzonite and granodiorite. One borehole,(HD83-27),near the downstream cofferdam encountered an II-foot section of fine-grained andesite.Core recovery.within the bedrock generally ranged from 90 to 100%,with RQD values typically above 50%.With the exception of local shear zones and altered rock all of the cored bedrock is fresh,and hard. 5.2.3 Structure Structures revealed during the drilling program were primarily joints and shear zones.Joints are generally vert ical,and joint spacing 5-8 - - - -. ..-, - ..... r varies from less than an inch to several feet.Most joint surfaces are fresh or slightly weathered,and generally rough.Calcite deposits are found as joint fillings or as light coat ings on joint surfaces.The quantity of drilling water lost through joints varies from 0 to 100%. A few of the boreholes encountered zones of moderately to severely fractured and jointed rock,for example Borings HD83-l0,43 and 44 . Core recovery ~n the fractured areas ~s usually high,although RQD values are low.Some areas are associated with loss of drilling water, although many are not.In general,the closely fractured sections of the borings appear to be localized and represent a small portion of the recovered cores. Evidence of local shear zones and gouge was encountered near the Fingerbuster shear zone near the downstream cofferdam (Hole HD83-27). A possible shear zone was encountered in Boring DH83-4 on the right abutment ,near the main dam centerline.This zone may be correlated with GF-5 as defined in the 1982 supplement (Figure 5.2).The orienta- t ion and extent of the zone is unknown.Coring within the shear zones ~s usually characterized by both poor core recovery and low RQD values. No significant drilling water loss was associated with these zones . 5-9 5.2.4 Weathering and Alteration Zones Typical surface weathering of diorite produces a rust-brown,1ron oxide staining.Weathering is usually developed to a slight or moderate de- gree in the bedrock cores.However,such weathering is usually surfi- cial,and restricted to the top of rock surfaces or along some joint faces.Penetrative weathering occurs in zones,a foot or more thick, indicated by decomposed feldspars and oxidized iron-magnesium minerals. Such penetrat i ve weathering was encountered near the right abutment of the main dam in hole DH83-4. Evidence of hydrothermal alteration of the diorite was more common than typical surface weathering.The al terat ion involves a hydrothermal chemical process which accelerates the decomposition of the rock as the feldspar minerals are altered to clay minerals.Such processes result in a bleached rock of variable strength dependent on the degree of alteration.Most of the altered diorite sampled appears to be only mildly altered.More extensive alteration appears to be associated with shear zones and zones of extens i ve fracturing.As discussed above,such zones form a minor percentage of the bedrock sampled. 5.2.5 Pressure Testing Hydraulic pressure testing 1n the bedrock was accomplished using mechanical packers.A total of nine tests were run,and yielded Lugeon values ranging between zero and 1xlO-3 em/sec.Table 5-3 summa- rizes the pressure test results.There is no apparent correlation bet- ween the observed severity of fracturing and the measured water loss. Although loss of return water was reported in over half of the borings, none of the measured Lugeon values are sufficiently high to have caused complete water loss. 5-10 - - ~. - - - .,.- -1 5.3 FOUNDATION CONDITIONS The following sect ions describe the specific foundat ion condit ion of bedrock and alluvium encountered at the proposed locations of the major project features,including the ma1n dam,upstream and downstream cofferdams,and at the diversion tunnel portals. 5 . 3 •1 Ma i n Dam The evaluation of the main dam subsurface conditions has been divided into three study areas covering the main dam centerline,the areas bet- ween the upstream toe,and between the downstream toe and the dam centerline. 5.3.1.1 Main Dam Centerline.Ten boreholes were drilled along the proposed centerline of the main dam.Seven-of the boreholes were drilled vertically,while three,near the channel sidewalls,were drilled at a 45 degree angle.The location of these boreholes is pre- sented in Figure 5-1.Downhole gamma surveys were completed in six of the boreholes.Hydraulic pressure tests were run in 3 of the borings and laborcl.tory testing was performed on selected overburden samples from each hole.Figure 5-9 presents the geologic profile of the river channel at the main dam centerline along with borehole logs,gamma logs and pressure test results. The bedrock channel is generally symmetrical 1n cross-sect ion,with sidewall slopes of approximately 40 to 50 degrees.The base of the bedrock channel 1S about 300 feet wide and ranges in elevation from about 1370 feet to about 1400 feet.The channel is deepest along the north side. 5-11 The bedrock core from boreholes along the centerline consist primarily of fresh and altered diorite.The rock varies from moderately to closely fractured.Local zones of deeply weathered or altered diorite were encountered,primarily in the boreholes on the north side of the channel.Core recovery averages 90%,although recovery in the weather- ed or altered material ranged as low as 25%.In areas of good core recovery,RQD values average 80%on the south side of the channel, dropping to about 50%on the north side in the vicinity of the bedrock depression.Only one zone of low RQD was encountered,located near the middle of the channel.The distribution of RQD and core recovery values suggest that the rock materials on the north side of the channel are,in general,more fractured or altered than those on the south side.The more extensive erosion evidenced by the deeper bedrock in this area may reflect differences in rock strength or fracture fre- quency. The alluvium along the ma~n dam centerline var~es ~n thickness from a maximum of about 93 feet on the north side of the channel to an average thickness of 70 feet across the remainder of the channel.Two of the four primary types of materials identified ~n the river channel are present ~n this area.Well-graded alluvial sandy gravel (GW-GM) accounts for 67%of the total materials sampled,and a poorly-graded gravelly sand (SP-SM)account for the remaining 33%.The average gradations are shown on Figure 5-10.An average of 21%of the sandy gravel sampled consist of +3/4"fragments broken by the drilling opera- tion.Similarly,an average of 13%of the gravelly sand samples con- sist of broken fragments.Gradation curves showing observed ranges in gradation are presented in Volume 2,Appendix D,Figures D-1 and D-2. The alluvial sandy gravels and gravelly sands deposits are lenticular. Grain size and gamma log data indicate that the gravelly sands are 5-12 - '""" - - ".... j !""'" I .... I f"" I generally found in the central part of the channel,while the coarser sandy gravels are focated along the outer perimeter.The single exception is a buried gravel lens located in the center of the channel, about 25 feet below the river level. Boulders and cobbles were encountered along much of the bedrock alluvium interface. The alluvial matj:!rial 1S expected to be very pervious.Partial or com- plete water loss from the drilling was noted in several sections of the bedrock,although pressure tests in bedrock in both the north and south abutments did not indicate appreciable water loss. 5.3.1.2 Upstream Area.Four vertical holes were drilled 1n the area upstream of the dam centerline,three of which were drilled in the ex- posed gravel bar on the north side of the channel,and one hole in the center of the channel,as shown on Figure 5-1.Downhole gamma logging was completed in two of the boreholes,and laboratory testing was per- formed on selected samples from each hole.Figure 5-11 presents summary borehole logs,gamma log curves and results of permeability tests. The bedrock floor,1n this portion of the river channel drops in elevation from 1450 feet along the margins of the channel to less than 1,310 feet within two apparent ly closed bedrock depress ions shown on Figure 5-8.The bedrock samples recovered from these depressions are closely-fractured,fresh and altered,friable diorite.The percent recovery and RQD values of core taken in this area were less than the typical values for much of the river channel bedrock,and average about 80%and 35%,respectively.The upstream most depression may correlate with geologic feature GF-2 as mapped pr~viously on the abutments (See Acres American,1982;Figure 5.2). 5-13 Three types of overburden material are present ~n this sect ion of the r~ver.The average gradation of each of the materials ~s shown on Figure 5-12.Gradation curves showing the range of materials encount- ered are presented in Chapter 2,Appendix D,Figures D-3 through D-5. Well-graded sandy gravel (GW-GM)account for 66%of the total materials sampled.An average of 24%of the samples retained on the 3/4"sieve consisted of fragments broken during drilling. Well-graded gravel (GW)accounts for 25%of the material.Almost 40% of the samples retained on the 3/4"sieve consisted of fractured particles. Gravelly sand accounts for the remaining 9%of the sampled material. An average of 15%of the sampled material consists of broken fragments. The coarse,well-graded gravel and sandy gravel sampled ~n this area represent a large buried gravel bar,deposited on the ins ide of the curve in the r~ver.This buried bar is part of the gravel bar exposed at the surface,and extends vert ically to a depth of over 140 feet as indicated in HD83-37. The permeability of the alluvial materials ~s expected to be high as evidenced by Boring HD83-39,which repeatedly encountered 1 to 5 foot intervals of materials yielding relatively high amounts of water in the return air circulation system.Water pressure testing in boring HD83-3 yielded moderate water losses in the bedrock.- -the main dam Army Corps of located approxi- 5.1.3.3 Downstream Area.The area downstream of centerline was investigated previously by the u.s. Engineers in 1978.Their Boreholes DH-4 and DH-5 are 5-14 ,.... ..... ,- - .- mately 800 feet downstream of the ma~n dam centerline.These holes encountered 65 and 51 feet.respectively.of river gravels.cobbles and boulders and some sand.The bedrock section of borehole DH-5 encount- ered a shear zone (with slickensides and gouge)and alteration roughly 22 feet below rock line.Loss of drilling water was experienced in the upper part of this zone. Farther do'wnstream.the USCE drilled three boreholes about 1.700 feet downstream of the main dam centerline.Because of equipment diffi- culties.alluvial deposits were difficult to penetrate.useE borehole DH-l encountered boulders up to 3.7 feet ~n diameter.Borehole DH-3 encountered boulders to 3.5 feet in diameter from a depth of 64 feet to the top of rock at a depth of 78 feet.Borehole DH-2 did not penetrate beyond 29 feet of alluvium ~n four attempts. Two new boreholes were drilled during the Winter 1983 program ~n the area between the dam axis and the downstream toe.Figure 5-11 presents boring logs.gamma log curves and permeabil ity test results for the borings in the downstream area.The two holes.0083-35 and 36.are approximately 1.500 feet downstream of the ma~n dam centerline.as shown in Figure 5-8.The holes were drilled m an exposed gravel bar. and the material s recovered are all class ified as well-graded sandy gravel (GW-·GM).The average gradat ion and envelope of gradat ions of the material are presented on Figure 5-13. The sandy gravels in the downstream area represent a gravel bar on the ins ide bank of a curve in the n ver.The material is presumed to have a high degree of permeability. The bedrock in the downstream area ~s intensely to moderately fractur- ed.slightly altered diorite.Core recovery was approximately 5-15 90 percent,while RQD values were much lower,ranging from 80 percent in one borehole to less than 40 percent in the other boreholes. 5.3.2 Upstream Cofferdam Eight vertical boreholes and one angle hole were drilled along the pro- posed axis of the upstream cofferdam,as shown on Figure 5-8,Profile C-C.Downhole gamma surveys were completed in five of the borings,and several permeability and bedrock hydraulic pressure tests were run.A geologic cross-section at the upstream cofferdam showing boring logs, gamma curves,permeability and pressure test results ~s presented on Figure 5-14. The bedrock channel ~s generally symmetrical in cross-section,with sidewall slopes of ranging from 30 degrees to 70 degrees.The base of the bedrock channel is roughly 300 feet wide,with an average elevation of about 1385 feet.The base of the channel is relat ively flat,with the exception of a bedrock knoll near the south side of the channel. Bedrock sampled ~n this area is generally unweathered,hard diorite, although some altered diorite was encountered in the mid-river bore- holes (HD83-l9 and 20,and in angle Hole HD83-4l on the south side of the channel.Core recovery was the highest of any sect ion drilled ~n the river,averaging over 95%recovery.RQD values were found to be slightly higher than average,ranging from 30%to 85%. The alluvium in the foundation area of the upstream cofferdam varies ~n thickness from 85 feet in a slight bedrock depression (Boring HD83-Z2) to 66 feet at the adjacent Boring HD83-Zl).All of the four primary types of material identified in the river channel are present in the area of the upstream cofferdam.Well-graded sandy gravel (GW-GM) accounts for 57%of the total materials sampled.Poorly-graded gravel- 5-16 - ~I - .-I' -! .-, ly sand (SP-SM)accounts for an additional 26%,while the remainder of the materials are a well-graded gravel (GW)and a poorly-graded sand, accounting for 13%and 4%,respectively.The average gradation 9f each of these materials is shown in Figure 5-15.The percentage of broken fragments in the recovered samples ranges from over 30%in the gravels to less than 4%in the sands.More detailed gradation curves showing the range of gradations measured are presented in Chapter 2,Appendix D,Figures D-6 through D-9. The distribution of materials within this section of the r~ver ~s related to the "s"shaped geometry of the canyon in this stretch of the r~ver.The coarsest materials containing boulders and cobbles occur at the extreme outside of the curves in the river.On the inside portion of the curves,large gravel bars have formed,consisting primarily of the coarse gravels and sandy gravels.The gravelly sands and sands, which comprise the finest materials sampled,are generally found within the central parts of the channel,and along part of the outside curves. The permeability of the alluvium ~s estimated to be high.Permeability tests ~n the finer materials indicates values ~n the range of 2 X 10-2 to 1 X 10-1 em/sec,while Boring HD83-22 recorded large volumes of excess water in the return circulation throughout most of its length. 5.3.3 Downstream Cofferdam Eight vertical boreholes and one abutment angle hole were drilled along the foundation for the proposed axis of the downstream cofferdam,as shown on Figure 5-8,Profile A-A.Downhole gamma surveys were com- pl~ted ~n nx of the holes,and labortory testing was performed on selected soil samples from each hole.Figure 5-16 present s the geo- 5-17 logic profile of the river channel at the downstream cofferdam,includ- ing summary boring logs,gamma curves,and permeability test results. The bedrock channel 1S generally symmetrical 1n cross-section,with both sidewalls showing a significant break 1n slope.The upper channel sidewall s apparent ly slope at about 70 to 80 degrees,while the lower sidewall s slope at 35 to 40 degres s •The base of the bedrock channel is about 300 feet wide.The bottom of the channel is gently undulat- ing,with a total relief of about 30 feet.The average elevation of the base of the bedrock channel is about 1380 feet. Bedrock 1n the downstream cofferdam foundation area 1S generally fresh or altered diorite.Core recovery values,with a few exceptions, were very high.RQD values typically ranged from zero in the shear zone in HDB3-27 to 80%in the altered diorite.One six-foot interval of altered and sheared diorite was encountered 1n borehole HD83-27 underlying 12 feet of fresh,hard,andesite.On the south side of the channel,Boring HD83-24 encountered a l4-foot thick interVal of hard, fresh diorite above a four-foot sect ion of alluvium.This interval of diorite may represent an overhang in the bedrock channel wall,or a large slide block in the channel alluvium. The thickness of overburden in this area ranges from 73 feet (HD83-26) in the middle of the sect ion to 59 feet (Boring HD83-3l)on the north s ide of the channel.All four of the material types ident if ied in the r1ver channel occur 1n the downstream cofferdam area.Well-graded sandy gravel (GW-GM)accounts for 75%of the total materials sampled. Poorly-graded gravelly sand (SP-8M)accounts for an additional 20%. The remaining 5%0 f the materials are a well-graded gravel (GW)and a poorly-graded sand.The average gradat ion of each of the sediment s is shown in Figure 5-17.The percent age of broken fragment s 1n the samples range from an average of 38%in the gravels to 4%in the sands. 5-18 - -. - - ...., f"'>, I r - -: - More detailed gradation curves showing the range of gradations sampled are presented in Chapter 2,Appendix D,Figures D-10 through D-14. The coarsest of the materials sampled occur at the base of the channel and in the shallow gravel bar on the south side of the channel.The sandy gravels and gravelly sands are distributed throughout the sec- tion,although some concentration of the finer materials occurs with depth along the north side of the channel. The permeability of the overburden will vary significantly based on the wide range of gradations.Relatively large amounts of water in return c irculat ion was reported from a sand layer at a depth of 48 feet in borehole HD83-25,within a short sand interval at 40 feet in HD83-26, and locally in HD83-29 and HD83-27. 5.3.4 Diversion Tunnel Portals The exploration of the diversion tunnel portal area was primarily de- s igned to develop the characteristics and topography of the bedrock ~n the threshc)ld area of both the upstream and downstream portal areas.A discussion of the findings in each of these two areas ~s presented below. 5.3.4.1 Upstream Portal.Four vertical holes were drilled near the upstream portals.Three were drilled adjacent to the north bank of the river channel (DH83-l4,15,and 16)and one was drilled approximately 900 feet upstream of the upstream cofferdam axis (HD83-2),as shown in Figure 5-1 and 5-11. The very coarse alluvium and talus blocks from the adjacent rock cliffs on the north bank vary in thickness from 11 feet (HD83-16)to 29 feet (HD83-l4).HD83-15 and 16 both required 3 attempts to reach bedrock because of the very coarse 5-19 overburden materials.Another nearby borehole,HD83-40,required 5 attempts and did not reach bedrock.Although the size of material deflecting the drive pipe 1S not known,it can be expected that boulders in the 2 to 5-foot diameter range are present. The majority of samples from this area classified as well-graded sandy gravels (GW),with 25%fractured material remaining on the 3/4-inch sieve,as shown in Figure 5-18.Approximatel y 60%0 f the material is classified as gravel,with 35%sand and 5%fines. Bedrock in all four boreholes was fresh,moderately fractured diorite. Bedrock elevation varies from 1446 (Boring HD83-l6)to elevation 1424 (Boring HD83-2).Percent recover1es ranged from 90 to 100%,while RQD values ranged between 70%and 100%. - .... 5.3.4.~Downstream Portal.Three verical boreholes were drilled 1n the area of the downstream portal area 1n the gravel bar adj acent to the north bank of the channel as shown 1n Figure 5-1 and 5-11.The alluvium in this area varies in thickness from 7 feet (Boring HD83-34) to 22.5 feet (HD83-32),becoming shallower downstream along the north bank of the river channel. Two types of materials are present In this section of the r1ver. Well-graded sandy gravel (GW)accounts for 84%of the total materials sampled.Well-graded gravel (GW)accounts for the remaining 16%of the material m1X.The average gradat ion of the two main material types is shown on Figure 5-19.An average of 20%to 30%of the material sampled contained broken fragments.More detailed gradation curves showing the range of gradations encountered are presented in Chapter 2,Appendix D, Figures D-14 and D-15. 5-20 ~\ - - - ,.... I - The elevation of bedrock r~ses ~n the downstream direction from an elevation of 1425 feet (HD83-32)to elevation 1445 (HD83-34).The bedrock sampled was found to be slightly weathered diorite with high percentage recovery and low RQD values due primarily to zones of closely fractured rock.The bedrock was found to be hard and moderately strong even in zones of low RQD. 5-21 6.0 RELICT CHANNEL INVESTIGATIONS 6.1 GENERAL 6.1.1 Relict Channel Morphology 6.1.2 Bedrock Exploration and Lithology 6.2 OVERBURDEN STRATIGRAPHY 6.2.1 Classification Criteria 6.2.2 Stratigraphic Units 6.2.3 Stratigraphic Correlation 6.3 OVERBURDEN PHYSICAL PROPERTIES 6.3.1 Soil Types 6.3.2 Texture and Plasticity 6.3.3 Density 6.3.4 Permeabi 1ity 6.4 GROUNDWATER 6.5 PERMAFROST ..- - - -I ! 6.0 RELICT CHANNEL INVESTIGATIONS 6 . 1 -GENERAL The existence of relict channels in the bedrock topography between the Susitna River valley and the tributary valley of Tsusena Creek near the Watana Dam site was originally indent ified by the U.S.Army Corps of Engineers explorations at the Watana site (Corps of Engineers,1979). Feasibility stage explorations of the relict channel from 1980 through 1982 by Acres American Inc.have developed detailed information on the bedrock topography,glac ial strat igraphy and propert ies of the glacial/fluvial deposits (Acres American Inc.,1982). The results of the winter program supplemented the previous stratigraphic interpretation and evaluation of engineering properties of the glacial deposits in the relict channels at three locations defined as being of primary interest from prevIous exploration results. The locations explored are shown on the Exploration Map,Figure 6-1. 6.1.1 Relict Channel Morphology The winter drilling results did not change significantly the interpre- t at ion of the bedrock topography In the area of the Watana ReI ict Channel.Figure 6.2 shows the configuration of the bedrock surface as interpreted from the seismic refraction lines and boreholes which al so are ,shown.Geologic profiles on Figures 6-3,6-4,and 6-5 show the interpreted bedrock surface and present summary boring logs,gamma curves and field and laboratory test results. Watana Relict Channel IS the term used in previous studies to denote a number of buried bedrock paleo-channels,ancestral to the present Susitna drainage.They are located In the area on the north side of 6-1 the Susitna valley between the mouth of Deadman Creek and a point about 1,000 feet upstream from the proposed dam axis and thence extending IIQDIfI northwesterly to Tsusena Creek.The development of the channels has wall then The -most Two been postulated (Acres American Inc.,1982)to have occured during pre-Wisconsinian time with modifications occuring during Wisconsinian interglacial stages. The thalweg of the deepest channel trends westerly for about 5,000 feet commencing at a breach in the bedrock of the Susitna valley north just downstream of the Deadman Creek confluence.The thalweg turns and trends northwest for about 7,000 feet to Tsusena Creek. bedrock floor of this deepest channel is about elevation 1825 over of its westerly reach and is deeper both upstream and downstream. secondary channels in the north bedrock valley rim have been interpret- ed about 2,000 feet and 4,000 feet upstream of the dam axis and these have been cut to elevations of 2,050 feet and 1,950 feet respectively. During subsequent development of Susitna drainage,the present main Susitna valley has cut its bedrock channel to elevation 1380. The relict channels have been found to be backfilled with fluvial and glacial deposits which are described and discussed in Section 6.2.2. 6.1.2 Bedrock Exploration and Lithology The exploration program completed at Watana relict channels consisted of 15 boreholes and a total of 2,140.5 feet of drilling as listed in - ,~, """ Table 4-4 and at locations shown on Figure 6-1.Four piezometers and nine thermal probes were installed in borings as shown in Table 4-9. Rock was encountered 1.n five of 15 borings and bedrock verified 1.n three of those borings.In HD83-52,the bedrock was cored and found to be fresh,unweathered diorite.In HD83-2,-6,and -8,bedrock appeared 6-2 MJi ,..,.. ,- ..... .- ,..,.. ..... ,..,.. to be weathered but the drilling method precluded identification of the rock lithology.In HD83-6,from 114.0 to 116.5,a white to yellowish brown clayey sand material was penetrated that resembles gouge pre- viously observed in outcrop in the damsite area. Bedrock surface elevations which are reasonably close to the bedrock elevation contours presented in the 1982 Supplement Report are present- ed in Figure 6-2.The deepest boring,HD83-52,encountered bedrock very close to that predicted by previous contour mapping.Bedrock 1.n other borings was within 10 to 30 feet and in WW-3 bedrock was about 50 feet higher then shown by contour maps.Seismic refraction data,which formed the basis for most of the bedrock surface topography,has not yet been reinterpretated uS1.ng the new bedrock surface data for correlation.Borings HD83-2 and HD83-8,did partially confirm the depth and limits of a secondary channel.An intermediate boring, planned to confirm the approximate depth at the deepest part of this channel,could not be drilled because of equipment limitations . 6.2 OVERBURDEN STRATIGRAPHY The topography of the upper Susitna River Basin has been modified by repeated glaciations as coalescing ice masses from both the Talkeetna Mountains and the Alaska Range merged and filled the broad plain of the Watana dam site area (Karlstrom 1964;Pewe,1975).As a consequence of these glaciations,the overburden deposits filling and overlying the Relict Channel on the north abutment at the Watana site are comprised of a sequence of glacial and fluvial materials. Five basic deposits have been differentiated based on their mode of deposition:1.ce disintegration,outwash,lacustrine,till,and alluvium.The system of identification of these deposits,originally by Acres Amrican Incorporated (1982)and further developed 1.n this 6-3 investigation,are based on samples collected ~n drilling,mapping of outcrop exposures,in-hole testing and geomorphology.Although not always clearly defined,12 stratigraphic units (designated A through K) have been delineated within these deposits and are shown in Table 6-1. 6.2.1 Classification Criteria The physical properties used to distinguish the units are color,gra~n size,roundness of coarse part ic1es,striat ions and polish,compact- ness,imbrication,structure,lithology,sorting and weathering.The main criteria used in distinguishing between the various deposits are as follows:- Alluvium Ice Disintegration Lacustrine Outwash Till roundness of the coarse fraction,the general absence of fine material,i.e.,clean,and well sorted morphology structure;grain s~ze high percentage of fines,absence of coarser particles roundness of the coarse fract ion,grain size, generally the material gets coarser with depth striations,polish and roundness of the coarse fraction,grain size,density None of the individual properties listed above,by themselves,are in- dicative of the type of deposit.Due to the complexity of the erosion- 6-4 - ,...", r - al and depositional processes associated with glacial environments,the variation in physical and material properties between units was,~n many instances,most difficult to ascertain. 6.2.2 Stratigraphic Units The descriptions of the stratigraphic units,particularly the upper units as defined by Acres American Incorporated (1982),have been modi- fied as a result of using the Becker Hammer Drill during the winter 1983 program and is reflected in the descriptions of the units in Table 6-1.The drilling equipment and method of sampling as discussed earlier in Section 4.2 and in Appendix B.enabled recovery of coarser material than that which had been recovered previously.Brief descriptions of the overburden stratigraphic units which have been delineated in the Relict Channel/Borrow Site D area are as follows: UNIT AlB -Surfical Deposits -is the uppermost material and consists primarily of organic silts,peat and cobbles and boulders which have been brought to the surface through frost heaving.Wi thin this thin (0-8 feet)nearly continuous material,thin volcanic ash layers have been delineated (University of Alaska Museum,1982).Post glacial ero- s~on of this material has resulted in soil formation,organic decompo- sition and frost heaving.In poorly drained or undrained areas,peat and organic silt deposits have formed.In low depressions usually occupied by small ponds and lakes,boulder fields are found where cobbles and boulders have been heaved'to the surface by frost act ion. UNIT C -Ice Disintegration Deposit -is characterized by a hummocky, knob and kettle topography which forms a discontinuous mantle across the area.It is found predominantly in the northern and northwestern portions of the Relict Channel/Borrow Site D area.The unit LS composed of a brownish grey to greyish brown,gravelly sand to silty 6-5 sand with little to some subangular to subrounded gravels and cobbles. It is usually poorly sorted,but in a few local areas ~s well sorted. The degree of compac t ion is variab le,though dens i ty tend s to increase with depth. UNIT M -Basal Till -Found near the Susitna River ~s a basal till ranging in thickness up to 79 feet.It ~s a brownish grey to dark grey,silty sand to clay with angular to subrounded striated gravel s, and some cobbles and boulders.It is dense to very dense,moist,poor- ly sorted,and occasionally frozen. UNIT D -Alluvium -~s a local alluvium found within channels ~n the underlying outwash surface,Unit E/F.Where eros ion of the overlying ice disintegration deposit has occured,this unit ~s found near the surface. The unit ~s composed of grey stratified sands and sil ts,with sub- rounded to rounded gravels and cobbles.It is generally sorted,medium dense to very dense,moist,and its thickness ranges up to 40 feet. - UNIT D'-Lacustrine ~s a discontinuous lacustrine unit.It ~s generally found in local depressions on top of the underlying outwash unit (E/F).The unit is composed of a grey to very dark greyish brown, laminated clayey silt to clayey,silty sand with small amounts of angular to subangular gravel.It is moist to wet,dense to very dense and frozen ~n some areas.Its maximum thickness is in the range of 23 feet. UNIT E/F -Outwash -forms a thick continuous mantle over the Relict Channel/Borrow Site D area.In areas not overlain by ice disintegration material,this unit is exposed at the surface and ~s characterized by a relatively flat,poorly drained surface.It averages 40 feet thick but 6-6 .-, - - -ranges to a maximum of 131 feet 1.n the northeastern port ion of the area,near Deadman Creek. It is composed of an olive brown to greyish brown matrix with varying amounts of silt,sand,gravel,cobbles,and boulders.The percentage of coarse material ranges from 5 to 60 percent,result ing in a material which ranges from a well graded silty sand with little gravel and,-cobbles well graded sandy gravel with occasional cobbles andtoa boulders.The coarse particles are subangular to subrounded and 1.n ..-general,the S1.ze and percentage of coarse material 1.ncreases with depth.The material 1.S dense to very dense,moist to wet,poorly .-sorted and frozen in some areas . UNIT G -Lacustrine -1.S a relat ively cont inuous lacustrine and/or till.- deposit with minor gaps in the strata.This unit together with the underlying till deposit,Unit G',forms a continuous,easily identifi- able marker strata across the area. feet,averaging approximately 30 feet. It ranges in thickness up to 74 The unit 1.S composed of blue grey to dark grey,laminated sandy silt to silty clay material with small amounts of gravel.The laminated lacustrine material consists of rhythmic interbeds of clay and fine silt.The unit is dense to very dense,moist to wet,locally frozen, particles are subanglar to rounded,and occasionally striated. eastern and western portion of the Borrow Site and 1.n the Relict Channel areas.It has a maximum thickness of 231 feet . is a basal till found in isolated patches 1.n the -j - ..... containing trace amounts of organics and is poorly sorted. UNIT G'-Basal Till The coarse ..... The unit ranges from an olive grey to very dark grey clayey,silty sand with minor amounts of gravel,to a gravelly,silty or clayey sand . 6-7 The coarse particles,which include occasional cobbles and boulders are subangular to subrounded with striat ions and pol ish.The material 1S dense to very dense,moist,occasionally frozen and poorly sorted. UNIT I -Outwash Deposit -1S nearly continuous stratum found over much of the Relict Channel/Borrow Site D area.It ranges in thickness up to 81 feet.The unit ranges from an olive to olive grey,well grad- ed silty sand with minor amounts of gravel and cobbles.The cobbles are slightly weathered,with limonite and some hematite staining.The coarse material is primarily subangular to subrounded with a trace of UNIT H -Alluvium -is local alluvium found 1n channels on the upper surface of the underlying outwash,Unit I.The maX1mum thickness is in the order of 42 feet.The unit is composed of greyish brown to olive grey well graded silty sands and sands with minor amounts of well grad- ed sandy gravels.The coarse material 1S generally sl ightly oxidized and rounded but subangular to subrounded particles.The unit 1S stratified,sorted and contains trace amounts of organics.It is moist to wet,very dense,and a relatively clean material. rounded particles,some particles are striated. wet,very dense and sometimes sorted. The unit is moist to - - UNIT J'Lacustrine and/or Stratified Deposits 1S a local ized fluvial and/or lacustrine deposit found 1n the northern and south- western portions of the Relict Channel/Borrow Site D area.It is found overlying bedrock and in topographic lows on the surface of the under- lying till,Unit J.It ranges in thickness up to 58 feet.The unit is composed of olive grey to olive brown,silty sand with a trace of sub- angular to rounded gravel to a sandy gravel.It is very dense and mod- erately weathered,with limonite staining and is well sorted to partly sorted. 6-8 - UNIT J -Basal Till Deposit -Maximum thickness of the basal till found 1.n the relict channels is in the order of 62 feet.It is an olive grey to dark grey,clayey sand to clay with small amount s of gravel.The gravel 1.S rounded to angular,slightly weathered with some limonite .- staining,striated polished.is possibleandTherea change at the bottom of the unit to a lacustrine or waterlain till deposit.It is-very dense and poorly sorted. UNIT K -Alluvium -is the oldest and deepest unit in the ReI ict Channel/Borrow Site D area.It 1.S found in the deepest part of the V-shaped valley comprising the main Relict Channel. The unit 1.S composed of very dense olive grey,silty sandy gravel and a poorly graded sandy gravel.The coarse fract ion which includes cobbles and boulders,is subangular to rounded,slightly weathered and well sorted. 6.2.3 Stratigraphic Correlation The overburden materials as classified above have been del ineated and correlated across the Relict Channel/Borrow Site D area (Figure 6-3 through 6-5).In general,the outwash strata (Units E/F and I)a~d the marker bed strata,(the lacustrine and till deposit;.Unit G and G'), are cont inuous across the reI ict channel and borrow area.The excep- tion to this is adjacent to the southwestern portion of Borrow Site D where 1.n HD83-2 and 8,where no lacustrine or basal till were encountered. Correlation of the stratigraphic units was attempted through the use of natural-gamma,borehole geophysical logging.The complex stratigraphy and the variations of the materials within each stratum precludes the identification of stratigraphic boundaries with any reasonable level of 6-9 confidence. Appendix A. The natural gamma log profiles are presented 1n Volume 2 - Based on the geotechnical investigation,to date,the overburden deposits beneath and including the lacustrinelwaterlain till and the basal till strata (Unit G and G')are generally dense and overconsolidated.A contour map of the top surface of the relatively impervious marker bed strata (Unit GIG')is shown in Figure 6-6.It appears that the surface of the strata forms a northeast-southwest topographic ridge that approximately coincides with seismic line DM-A (Note,the borings are also concentrated along this trend). Boring HD83-49 is about in the middle of the topographic low and is the low point in/the surface of Unit GIG'at elevation 2187 (Figure 6-4). The other topographic low 1n the surface elevation of Unit GIG'occurs 1n the vicinity of boring HD83-4 at elevation 2200.The thickness of ~ overlying Units C,and ElF varies from 10 to 70 feet along Profile B-B, Figure 6-4. The existence of the deep Unit K alluvium was further verified with boring HD83-l,which penetrated the top part of Unit K about 34 feet higher than it was encountered 1n Corps of Engineers boring DR-22, ~I - located about 700 feet to the north towards Tsusena Creek.Although only 35 feet of the unit was penetrated,the bedrock contours suggest a unit thickness of about 130 feet at this location.The extent of Unit K along the deepest part of the main channel can be reasonably well estimated 1n the bedrock control section,but as is the case with all the lower units,it remains undefined at the entrance and exit areas of the relict channel. Unit I outwash was present in all borings drilled through the overlying Unit GIG'except where GIG'was absent at boring HD83-2.Unit H allu- 6-10 ,.•..\. ~. - v~um was often present as a more permeable unit on the surface of the Unit I outwash.Thus,the relatively more permeable Units I and Hare present throughout much of the area of reI ict channel invest igat ion in the winter program. The winter program results add valuable informat ion to the data base for borrow materials above Unit GIG'.The six borings drilled along or near the limits of Borrow Site D add to the data on volume of borrow materials evaluated in the 1982 Supplement Report.No significant variations in stratigraphy affecting borrow quantities were determined during the winter program. The soil property data for units above GIG'provide additional informa- tion to add to that summarized in the 1982 Supplement Report.The grain size curves,Atterberg Limits,and moisture contents for units correlate well with the results of previous explorations as shown in Appendix D,figures D-22 and D-23,D-34 and D-35,and D-37 through D-40. 6.3 OVERBURDEN PHYSICAL PROPERTIES 6.3.1 Soil Types The var~ous types of soils encountered ~n the glacial deposits were classified in accordance with the Unified Soil Classification System, The soil descriptions are based on field and laboratory visual examina- tion,on results of laboratory and field testing and on observations of drilling behavior.Typical group classifications for each geologic unit of the glacial deposits are provided on Table 6-1. The soil type (8M)is typical for glacial till Units M,G',and J',and is common in the outwash deposits ElF and I as shown on Table 6-1. 6-11 Some silty sand (SM)is encountered 1n alluvial deposits D and H. Clayey sand (SC)soils are also common to many geologic units, particularly the glacial lacustrine and till deposits.These soils are generally absent 1n the outwash,Unit I,and 1n all the alluvial deposits.Cohesive clayey and silty (CL,ML)soils are generally 1 imited to lacustrine and till deposits.Gravelly material s (GM,GP, GW)are found in the alluvium of Unit K,and to a lesser extent,the outwash of Units J.and E/F.The coarseness of the outwash/alluvial deposits generally increases with depth.Unit K is coarser than Units J and H,which are coarser than E/F and D.Soil types with low fine contents (GW,GP,SW,SP)are limited to outwash Units E/F and I,and alluvial Units D,H,and K. 6.3.2 Texture and Plasticity Laboratory tests for soil grain size and plasticity were anaylzed for each geologic unit (C through K)tested in the winter program.Weight- ed average and upper and lower limits of the grain size distribut ion of all samples were determined for the var10US units.The average and range of soil types in each unit were compared with previous grain size distributions presented 1n the 1982 Supplement Report.When possible the summarized weighted averages and ranges for each unit 'were then compared by mode of deposition,(till,outwash,alluvium,lacustrine). Unit C,an ice disintegration deposit,was categorized with the outwash because of similar texture.A summary of the analyses or grain size distribution by geologic units is presented in Table 6-3. Till Units M,G',and the basal till deposit J had average grain S1ze distributions and a gradation envelope as shown in Figure 6-7.With the exception of clay materials in J,the deposits exhibit very similar average grain size characteristics and are predominantly silty,clayey sand to sandy clay with little gravel.The upper and lower gradation 6-12 - ~, - - limits of the till deposits include a wide variety of soil types from c lay to gravel.However,the weighted average distribution for each unit is very similar to previous results as shown 1n Appendix D, Figures D-16 through D-20.Each of the units is classified as low plastic with the Atterberg limits of the materials ranging from cohesionless to a plasticity index of approximately 10 and a liquid limit of 25 as shown in Append ix D,Figures D-37 through D-40.The limits disclosed in samples of winter program sampling were well within the range previously found in each unit. Outwash Units C,ElF,and I,are predominately stratified sil ty sand (8M)with layers or lenses of sandy gravel (GM).The average grain S1ze distribution 1S very similar for the two deposits as shown on Figure 6-8.In both Unit ElF,and I,two types of materials have been delineated which average gradations and envelopes very similar to the gradation trends from previous results as shown in Appendix D,Figures D-2l through D-26.Each of the units is classified as low plastic with the Atterberg limits of the materials ranging from cohesionless to a plasticity index less than 5 and a liquid limit less than 25 as shown in Appendix D,Figures D-37 through D-40.Upper and lower limits for winter program samples fall within the limits of previous results. Clean,granular soils (GW,8W)are present in the lower I outwash deposit,but were not detected in Unit ElF. 6-13 Alluvium Units Hand K are dissimilar ~n texture as shown on Figure 6-9.Unit H was predominantly a silty sand (8M)with layers or lenses of well graded sandy gravel (GW-GM)while Unit K was primarily a poorly graded sandy gravel (GP-GM)with layers or lenses of silty,sandy gravel (GM).Unit H sample test results from the winter program define a much coarser unit than samples from previous exploration as shown in Appendix D.The unit K data represents the only grain size distribu- tions which have been completed in the deep alluvium based on a limited pentetration of the unit (35 feet)and limited sample recovery. Lacustrine Units G,D',J I vary in texture from silty clay (CL)in G, sandy silty (ML)in D',to silty sand (8M)in J'as shown on figure 6-10.Unit J',a stratified silt and sand deposit was included for comparison purposes because of a similar mode of deposition. Comparison of winter program sample test results for each unit with results of previous explorations are provided in Appendix D,Figures D-34 through D-36.The winter program data correlate well with previous results. 6.3.3 Density The density of in-situ soil ~s normally estimated by blow counts on split-spoon samples (8PT)or measured by density testing of representative undisturbed samples.The high content of gravel and coarser materials throughout the glacial deposits and the compactmess of the deposits beneath the upper Unit C outwash material make undis- turbed sampling difficult if not impossible to accomplish.Undisturbed sampling was not included in the relict channels program due to exper- 6-14 ~I ience from previous explorations and the priority objectives of obtaining glacial strat igraphy and soil texture.Al though the finite .-, values are suspect because of the presence of gravel,standard penetration resistance blow counts on split-spoon samplers were used to further evaluate the density of the geologic units.Blow counts of the hannner drill were also used during drilling to qualitatively evaluate density by degree of drilling difficulty • The results of 71 penetration tests on split-spoon samples and hammer drill observations confirm previous exploration results.In general, glacial deposits beneath the Unit C ~ce disintegration deposits are generally dense to very dense.These deposits are overconsolidated by ~ce from the most recent major glacial advance over the area.The Unit AlB surficial deposits and Unit C ice disintegration deposits are not overconsolidated.These deposits are generally within the activel seasonal frost zone.Previous blow count data indicates the Unit C material is dense to very dense below a depth of 15 feet.At some boring locations,the surface ElF deposit was medium dense to dense where it was within about 15 feet below the ground surface. r- The blow count data ~s consistent with that presented ~n the 1982 Geo- technical Report.Of 38 data points in Unit G and G'5 were les s than, r-100 blows per foot and one was less than 50 blows per foot.Of 17 ~n Unit ElF,4 were less than 50 blows per foot,S were from 50 to 100 blows per foot and 8 were greater than 100 blows per foot. 6.3.4 Permeability Permeability of the glacial deposits varies significantly between the vertical and horizontal components of seepage due to the stratification and sorting of the soils during deposition.In addi t ion to soil structure,the permeability of the relict channel soils ~s directly 6-15 related to the grain size,density and particle shape of the deposits. All of the relict channel deposits below Units A/B,or C are evaluated to be dense to very dense. The interstructure and grain s~ze distribution of individual seams or lenses has not been accurately distinguished nor determined ~n the stratified relict channel deposits sampled by the hammer drill.The sampling method mixes the sample during retrieval,as a result the sample ~s a composite sample for the depth drilled,which varied from one to five feet. The soils within all units of the glacial deposits are generally well graded and contain appreciable fines.These textures tend to reduce the porosity of the soils. reduces the permeability. The high density of the soils further However,pervious sand and gravel deposits are present,particularly ~n the alluvium deposits.However perv~ous,~ the 35 feet of Unit K penetrated ~n boring HD83-l was not open work cobbles as postulated from the COE boring DR-22;rather it was silty gravel and sandy gravel,more similar in texture to the gravels in the present Susitna river channel. The extensive data on soil texture presented In Volume 2,Appendix D correlates very well with previous data for each of the units.The variation of grain s~ze distribution within stratified deposits ~s characterized ~n more detail from this data.This data provides a -reasonable basis for estimating permeablility and soil structure characteristics ~n future engineering studies of seepage in the relict channel. 6-16 - - - ..,. 6.4 GROUNDWATER The groundwater reg1me of the Relict Channel/Borrow Site D area is com- plex because of the variable characteristics of the var10US strati- graphic units ident ified and the presence of discont inuous or sporad ic permafrost.In general,the overburden deposits can be divided into potent ial aquifers (ice disintegrat ion deposits,outwash and alluvium) and into more impervious zones such as the dense lacustrine and basal t ill deposits.The existence of permafrost in potent ial aquifers may create blockage of groundwater flow and,therefore,port ions of the stratum might respond as an aquiclude. Limited information on the groundwater reg1me exists at the present time.During the winter drill ing program,groundwater was detected primarily in the outwash strata (Units E/F and I)above and below and the alluvial deposit (Unit H)below the lacustrine and/or basal till deposits (Unit G/G').Together,the lacustrine and basal till deposits form a continuous,thick impermeable strata across the Relict Channell Borrow Site D area,except for a small area near HD83-2 and 8 (Figure 6-6).It appears that surface recharge to the groundwater aquifers becomes trapped above this strata in the overlying materials and 1S generally very close to the ground surface. Groundwater recharge of the deposits beneath the impermeable strata (Unit G/G')is believed to be from the bedrock high to the southwest of the relict channel,where groundwater can follow bedrock and enter into the underlying pervious strata and/or surface infiltration in areas not overlain by the impermeable strata (Figure 6-6).No ground water was detected 1n the top 35 feet of the preglacial alluvium,Unit K stratum. 6-17 The detect ion of groundwater at only intermittent locat ions in the outwash and alluvium units above the till and lacustrine units may indicate that these units have drained to the adjacent Susitna river and Tsusena creek valleys.An exception to this is Where the permeable units fill lows in the underlying till and lacustrine units. 6.5 PERMAFROST The Watana Dam site area lies within a zone of discontinuous permafrost and has a mean annual temperature very close to freezing,roughly -1.5 ·C.During the winter drilling program,permafrost in the form of ice lenses and visible ice were detected in HD83-3 and 5 to a depth of 38 and 50 feet,respect ively.Thawing of ice lenses ~s indicated by abnormally high moisture contents at HD83-3.This is in good agreement with assumptions for permafrost resulting from borings during previous investigations (Corps of Engineers,1979;Acres American Inc.,1982). Permafrost has been detected primarily in the horizons above and inclu- sive of the lacustrine and basal till strata (Units G/G').The active layer in Relict Channel/Borrow Area D has been delineated and ~s generally from 5-15 feet deep Where permafrost is found. It appears,based on previous drilling information,that permafrost may locally reach depths of up to 110 feet below the ground surface. Instrumentation readings to date are indicative of a thermal regime that may be in disequi librium with the present climate.Only in 5 of 15 instrumented borings drilled prior to 1982,Which detected perma- frost,has freezeback occurred to temperatures at or below freezing, upon stabilization.Therefore,it appears that the growth or cont inued growth of permafrost is only marginal with the present climatic regime, however,this does not preclude its formation in localized areas. 6-18 I~ ~, - ~I pml """" REFERENCES REFERENCES 1.Acres American Incorporated,Susitna Hydroelectric Project, 1980-81 Geotechnical Report,1981. 2.Acres American Incorporated,Susitna Hydroelectric Project,1982 Supplement to the 1980-81 Geotechnical Report,1982. 3.Acres American Incorporated,Susitna Hydroelectric Project, Feasibility Report,1982. 4.American Geological Institute,Dictionary of Geological Terms, Dolphin Books,New York,545p.1962. 5.Karlstrom,T.H.V.,"Quarternary Geology of the Kenai Lowland and Glacial History of the Cook Inlet Region,Alaska",U.S.Geological Survey,Professional Paper 443,1964. 6.Pewe,T.L.,"Quarternary Geology of Alaska",U.S.Geological Survey,Professional Paper 835,1975. 7.U.S.Army Corps of Engineers,Hydroelectric Power and Related Purposes,Upper Susitna River Basin,Southcentral Railbelt Area, Alaska,Final Feasibility Report,1978. 8.U.S.Bureau of Reclamation,Earth Manual,1974. 9.University of Alaska Museum,Subtask 7.06 Cultural Resources Investigation,April 1982. TABLES .... - - - - .- TABLE 4-1 RIVER CHANNEL SUBSURFACE GEOPHYSICAL PROFILES FOOTAGE SUMMARY SEISMIC REFRACTION GROUND PENETRATING RADAR LINE LINE LINE NO.LENGTH,FEET LINE NO.LENGTH,FEET S83-1 430 R83-1 1200 S83-2 275 R83-2 1600 S83-3 500 R83-3 310 S83-4 1080 R83-4 800 S83-5 1100 R83-5 800 S83-6 1550 R83-6 1100 S83-7 1100 R83-7 288 S83-8 550 R83-8 384 S83-9 1705 R83-9 384 S83-10 1100 R83-10 230 R83-11 377 R83-12 324 R83-13 380 R83-14 313 TABLE 4-2 RIVER CHANNEL BOREHOLE GEOPHYSICAL LOGGING FOOTAGE SUMMARY ..... - BOREHOLE NUMBER HD83-20 HD83-2l HD83-22 HD83-23 HD83-24 HD83-26 HD83-28 HD83-29 HD83-30 HD83-3l HD83-34 HD83-35 HD83-36 HD83-37 HD83-39 HD83-42 HD83-43 HD83-44 HD83-45 HD83-46 HD83-48 DH83-4 LENGTH LOGGED,FEET 63.0 65.5 105.6 74.0 40.4 76.0 86.1 74.0 67.5 79.0 14.0 51.9 42.5 123.0 166.3 126.0 52.0 66.0 43.9 53.5 107.0 114.5 TOTAL DEPTH,FEET 76.5 86.5 107.3 87.0 57.0 96.0 88.5 104.3 75.6 82.9 32.4 71.5 43.6 155.0 168.0 127.8 107.7 118.0 80.0 98.2 108.0 116.5 LOCATION Upstream Cofferdam Upstream Cofferdam Upstream Coferdam Upstream Cofferdam Downstream Cofferdam Downstream Cofferdam Downstream Cofferdam Downstream Cofferdam Downstream Cofferdam Downstream Cofferdam Downstream Portal Downstream Shell Downstream Shell Upstream Shell Upstream Shell Dam Centerline Dam Centerline Dam Centerline Dam Centerline Dam Centerline Downstream Cofferdam Dam Centerline - TABLE 4-3 RELICT CHANNEL BOREHOLE GEOPHYSICAL LOGGING FOOTAGE SUMMARY BOREHOLE LENGTH TOTAL NUMBER LOGGED,FEET DEPTH,FEET HD83-4 58.7 94.0 HD83-5 78.0 138.0 HD83-6 91.5 126.5 HD83-7 80.3 82.0 HD83-8 78.0 78.0 HD83-9 106.0 110.0 HD83-49 37.0 38.0 HD83-50 118.0 119.5 HD83-51 94.0 98.5 LOCATION Seismic Line DM-A Seismic Line DM-A Seismic Line DM-A Seismic Line SL82-18 Seismic Line SW-3 Seismic Line DM-A Seismic Line DM-A Seismic Line DM-A Seismic Line DM-A ··1 'I f t .1 ~._.]"1 J I 1 1 1 TABLE 4-4 RIVER CHANNEL 1983 WINTER DRILLING PROGRAM DATA SUMMARY BOREHOLE SURFACE ELEVATION DEPTH TO BEDROCK TOTAL NUMBER(l)ICE OVERBURDEN INCLINATION AZIMUTH BEDROCK(2)ELEVATION DEPTH FEET FEET DH83-1 1,464.4 1,386.4 Vert.----78.0 1,386.4 91.0 DH83-2 1,470.6 1,466.1 II ----46.0 1,424.6 64.0 DH83-3 1,460.4 1,450.6 II ----92.9 1,367.5 126.5 DH83-4 1,475.2 1,473.8 45°350 0 22.0 1,459.6 116.5 HD83-10 1,459.4 1,455.9 Vert.----96.0 1,363.4 119.5 HD83-11 1,459.1 1,451.1 II ----73.2 1,385.9 89.4 HD83-P 1,459.0 1,451.5 II ----77 .0 1,382.0 87.5 HD83-13 1,458.5 1,449.5 II ----84.0 1,374.5 89.5 HD83-14 1,464.8 1,459.8 II ----34.0 1,430.8 57.5 HD83-15 1,465.1 1,460.1 II ----29.5 1,435.6 46.0 HD83-16 1,465.5 1,457.5 II ----19.0 1,466.5 39.5 HD83-17 1,464.4 1,449.4 II _...._-63.0 1,401.4 77.5 HD83-18 1,465.7 1,461.2 II ----30.0 1,435.7 39.0 HD83-19 1,463.5 1,453.0 II ----80.0 1,383.5 98.0 HD83-20 1,464.9 1,455.4 "-----------76.5(3) HD83-21 1,467.7 1,467.7 -----66.0 1,401.7 86.5 HD83-22 1,467.6 1,464.6 ----87.0 1,380.3 107.3 HD83-23 1,468.0 1,468.0 ----71.0 1,397.0 87.0 HD83-24 1,453.8 1,448.3 ----44.0 1,409.8 57.0 HD83-25 1,454.4 1,446.4 ----75.0 1,379.4 95.9 HD83-26 1,453.8 1,445.8 ----81.0 1,372.8 96.0 HD83-27 1,453.7 1,445.8 ----70.0 1,383.7 98.5 HD83-28 1,453.6 1,443.6 ----72.0 1,381.6 88.5 HD83-29 1,453.8 1,444.8 ----79.0 1,374.8 104.3 HD83-30 1,453.8 1,444.8 II ----65.0 1,388.8 75.6 HD83-31 1,456.2 1,455.2 II ----60.0 1,396.2 82.9 HD83-32 1,454.0 1,447.5 II _......_-29.0 1,425.0 57.8 HD83-33 1,453.2 1,445.7 II ----21.0 1,432.2 43.0 HD83-34 1,454.9 1,449.9 II ----12.0 1,442.9 32.4 1 I I 1.1 1 J,I 1 J ~~l 1 1 1 1 l 1 I 1 TABLE 4-4 RIVER CHANNEL 1983 WINTER DRILLING PROGRAM DATA SUMMARY BOREHOLE SURFACE ELEVATION DEPTH TO BEDROCK TOTAL NUMBER(1)ICE OVERBURDEN INCLINATION AZIMUTH BEDROCK(2)ELEVATION DEPTH FEET FEET HD83-35 1,458.4 1,455.9 Vert.----51.5 1,406.9 71.5 HD83-36 1,456.8 1,453.9 "----24.0 1,432.8 43.6 HD83-37 1,464.3 1,463.3 "_....._-153.5 1,310.8 155.0 HD83-38 1,463.6 1,461.1 "-------------94.5 (3) HD83-39 1,467.2 1,462.2 "----152.0 1,315.2 168.0 HD83-40 1,470.6 1,468.6 "--------------38.0 HD83-41 1,471.9 1,470.5 "098 0 83.0 1,413.2 104.5 HD83-42 1,462.1 1,451.1 Vert.-----70.0 1,392.1 127.8 HD83-43 1,461.1 1,451.1 "----75.4 1,385.7 107.7 HD83-44 1,459.9 1,449.9 "----67.5 1,392.4 118.0 HD83-45 1,463.5 1,462.8 "328 0 56.0 1,423.9 80.0 HD83-46 1,461.5 1,460.1 "155 0 55.5 1,422.3 98.2 HD83-47 1,459.6 1,458.2 "010 0 --""------65.0(3) HD83-48 1,455.6 1,447.6 Vert.----88.0 1,367.6 108.0 TOTAL 3,710.4 (1)Longyear boring,DH83-1.Hammer boring,HD83-1O (2)Depth to bedrock is along the hole axis (3)Refusal while drilling,(cobble/boulder or bedrock) ,....TABLE 4-5 RELI cr CHANNEL 1983 WINTER DRILLING PROGRAM DATA SUMMARY DEPTH TO(2)TOTAL BOREHOLE SURFACE (1)BEDROCK BEDROCK DEPTH NUMBER ELEVATION FEET ELEVATION FEET,- HD83-1 2,246.2 328.0 HD83-2 2,147.1 77 .5 2,069.6 87.0 HD883-3 2,220.0 82.5r-HD83-4 2,246.7 94.0 HD83-5 2,283.7 138.0 HD83-6 2,211.2 126.5 (2) HD83-7 2,095.5 82.0 HD83-8 2,217.2 78.0R HD83-9 2,237.6 110.0 HD83-49 2,205.5 38.0 HD83-50 2,289.0 119.5 HD83-5l 2,234.9 98.5 HD83-52 2,249.1 320.0 1,929(1)333.0 HD83-53 2,248.0 212.0 WW-3 2,267.0 206.5 214.5 TOTAL 2,141.5 (1)Surface Elevat ion is approximate (2)Refusal while drilling,(cobble/boulder or bedrock) - - - 1 'J 1 1 J 1 I -'1-·'1 -1 I J 1 1 TABLE 4-7 RIVER CHANNEL SUMMARY OF 1983 PROGRAM LABORATORY TESTING NUMBER OF SAMPLES AND SPECIFIC TESTS Boring No.of Visual Grain Hydrometer Atterberg Moisture OrganIc Specific Compaction No.Samples Class.Size Limits Content Content Gravity HD83 10 18 13 13 0 0 0 0 0 0 11 9 3 3 0 0 0 0 0 0 12 13 4 4 0 0 0 0 0 0 13 13 5 5 0 0 0 0 0 0 14 5 3 3 0 0 0 0 0 0 15 5 3 3 0 0 0 0 0 0 16 3 1 1 0 0 0 0 0 0 17 9 6 6 0 0 0 0 0 0 18 5 5 5 0 0 0 0 0 0 19 15 8 8 0 0 0 0 0 0 20 12 8 8 0 0 0 0 0 0 21 13 9 9 0 0 0 0 0 0 22 17 11 11 0 0 0 0 0 0 23 13 8 8 0 0 0 0 0 0 24 3 3 3 0 0 0 0 0 0 25 8 7 7 0 0 0 0 0 0 26 13 7 0 0 0 0 0 0 0 27 12 8 8 0 0 0 0 0 0 Page 1 of 2 J 1 1 1 1 J -1 1 -1 1 I --1 1 --I 1 1 TABLE 4-7 RIVER CHANNEL SUMMARY OF 1983 PROGRAM LABORATORY TESTING NUMBER OF SAMPLES AND SPECIFIC TESTS Boring No.of Visual Grain Hydrometer Atterberg Moisture Organic Specific -Compaction No.Samples Class.Size Limits Content Content Gravity HD83 28 10 8 8 2 1 0 0 2 0 29 11 6 6 0 0 0 0 0 0 30 10 6 6 0 0 0 0 0 0 31 11 6 6 0 0 0 0 0 0 32 5 3 3 0 0 0 0 0 0 33 3 2 2 0 0 0 0 0 0 34 2 1 1 0 0 0 0 0 0 35 10 6 6 0 0 0 0 0 0 36 4 2 2 0 0 0 0 0 0 37 26 14 14 0 0 0 0 0 0 38 19 10 10 0 0 0 0 0 0 39 26 14 14 0 0 0 0 6 0 40 6 3 3 0 0 0 0 1 0 41 16 9 9 0 0 0 0 4 0 42 11 8 8 0 0 0 0 2 0 43 12 9 9 0 0 0 0 0 1 44 11 8 8 0 0 0 1 0 1 45 11 5 5 3 1 0 0 0 0 46 11 6 6 0 0 0 0 0 0 47 12 7 7 0 2 0 0 0 0 48 15 9 9 1 3 0 0 0 0--- -------- Subtotal 409 258 258 6 7 0 2 16 2 Tot al :549 Tests- Page 2 of 2 1 I I 1 J 1 1 -I 1 -1 1 ---I ----1 -1 --I j I TABLE 4-8 RELICT CHANNEL SUMMARY OF 1983 PROGRAM LABORATORY TESTING NUMBER OF SAMPLES AND SPECIFIC TESTS Boring No.of Visual Grain Hydrometer Atterberg Moisture Organic Specific Compaction No.Samples Class.Size Limits Content Content Gravity HD83 1 58 50 48 11 11 23 2 0 0 2 23 17 17 0 6 16 0 0 0 3 13 6 5 2 6 13 0 0 0 4 14 12 12 3 9 6 0 0 0 5 20 14 12 7 7 9 0 2 0 6 21 16 16 7 7 2 0 2 0 7 9 7 7 3 2 6 0 0 0 8 16 8 8 2 3 0 0 0 0 9 21 12 11 4 5 0 0 0 0 49 10 7 5 2 4 1 1 0 0 50 28 15 15 11 3 0 0 4 0 51 35 15 14 1 11 13 1 1 1 52 93 52 50 14 28 16 0 4 0 53 24 16 16 6 14 1 0 3 0 Water Well No.3 44 33 34 1 4 0 0 1 0------------- Subtotal 429 280 270 74 120 106 4 17 1 Total 872 Tests '}--1 1 J --1 1 1 -I 1 '-I -)-1 1 I TABLE 4-9 RELICT CHANNEL SUMMARY OF INSTRUMENTATION INSTALLATION TYPE,DEPTHS,AND ELEVATIONS BORING SURFACE DATE PIEZOMETER PIEZOMETER READINGS,ELEVATION THERMAL PROBE NO.ELEVATION INSTALLED POINT DEPTH ELEVATION 3/83 4/83 5/83 TOTAL DEPTH-- HD83 2,246.2 2/18/83 225.0 2,021.2 2,147.0 2,059.3 2,060.4 230.0 HD83-2 2,147.1 2/07/83 75.5 2,071.6 2,162.8 2,127.0 2,127.0 HD83-3 2,220.0 NOT INSTRUMENTED HD83-4 2,246.7 2/09/83 57.0 2,189.7 2,247.4 2,242.8 2,246.2 60.0 HD83-5 2,283.7 2/10/82 70.0 2,213.7 2,299.4 2,264.5 80.0 HD83-6 2,211.2 2/12/83 125.0 HD83-7 2,095.5 2/12/83 82.0 HD83-8 2,217.2 2/13/83 80.0 HD83-9 2,237.6 2/13/83 110.0 HD83-9 2,205.5 3/20/83 38.0 HD83-50 2,289.0 3/21/83 119.5 HD83-S1 2,234.9 NOT INSTRUMENTED HD83-S2 2,249.1 3/26/83 333.0 HD83-S3 2,248.0 NOT INSTRUMENTED 1 -1 1 1 ]---1 "-1 1 1 -~-J 1 l TABLE 5-1 RIVER CHANNEL SUMMARY OF MATERIAL CLASSIFICATIONS MATERIAL %OF TOTAL NUMBER OF FEET %FRACTURED GRADING CLASSIFICATION MATERIALS SAMPLES SAMPLED +3/4 INCH-- GRAVEL 9.8 21 76 36.7 WELL GW SANDY GRAVEL 67.6 150 524 18.9 WELL GW-GM GRAVELLY SAND 21.4 50 166 11.5 POOR SP-SM SAND 1.2 6 10 3.8 .POOR SP-SM TOTALS 100.0 227 776 -J 1 1 1 I 1 ]-~ j ---1 l TABLE 5-2 RIVER CHANNEL IN-SITU OVERBURDEN PERMEABILITY TEST RESULTS BOREHOLE DEPTH DURATION OF TOTAL PERMEABILITY NUMBER TESTED (FT.)GEOLOGIC DESCRIPTION TEST (MIN.)HEAD (FT)(CM/SEC) HD83-l9 28 Fine to coarse sand and 19 3.5 1.5xlO-3 fine gravel trace silt, trace coarse gravel HD83-20 48 fine to coarse sand 30 5.0 7.4xlO-3 HD83-2l 18 fine to coarse sand and 30 8.0 5.0xlO-2 fine grave 1,trace silt/ clay 38 Medium to coarse sand,12 8.0 1.2xlO-l some grave 1,trace fine sandi silt 48 Fine to coarse sand,some 20 8.0 2.lxlO-2 fine to coarse gravel, trace silt/clay 58 Fine sand,trace medium 15 8.0 2.6xlO-2 sand,trace fine gravel, trace silt/clay HD83-22 28 Coarse sand,some fine 12 9.0 -21.lxlO to coarse gravel,trace fine sand/silt 58 Medium to coarse sand,12 9.0 1.lxlO-2 some fine to coarse gravel HD83-28 28 Coarse sand and fine 20 3.0 2.0xlO-2 grave 1,little fine sand and silt,trace to little coarse gravel. HD83-30 58 Coarse sand and fine 10 10.0 6.8xlO-2 gravel,some medium sand, little coarse gravel sub- rounded,grey saturated. "I ]1 I ]1 -1 1 -"I 1 1 ) TABLE 5-3 RIVER CHANNEL BEDROCK HYDRAULIC PRESSURE TEST RESULTS INTERVAL TESTED (ft ) GEOLOGIC DESCRIPTION DURATION PRESSURE OF TEST (min.)(psi) TOTAL HEAD (ft) PERMEABILITY (cm/sec) 55-64 Diorite)little to closely 5 15 39 fractured 5 30 73 5 45 108 5 30 73 5 15 39 DH83-3 105.3-Diorite)moderately to 5 15 38 114.3 closely fractured 5 30 73 5 45 107 5 30 73 5 15 38 DH83-4 40-49 81-100 97.5- 116.5 Diorite and altered dior- ite)closely to intensely fractured Diorite and altered diorite) moderately fractured Diorite and altered dior- ite)closely to intensely fractured 5 5 8 7 10 4 10 6 4 5 10 10 10 20 30 20 30 15 25 12.5 27 50 27 50 73 50 73 39 62 33 3.6 x 10-5 3.0 x 10-5 1.5 x 10-5 2.5 x 10-5 2.9 x 10-5 --------- 2.7 x 10-5 3.1 x 10-5 5.4 x 10-6 1.4 x 10-6 3.5 x 10-6 _......_....._---- 1.0 x 10-5 3.8 x 10-4 3.7 x 10-4 3.1 x 10-4 --------- 3.5 x 10-4 2.2 x 10-4 2.0 x 10-4 1.8 x 10-4 1.7 x 10-4 2.1 x 10-4_.....-------- 2.0 x 10-4 i 1 1 TABLE 5-3 Continued RIVER CHANNEL BEDROCK HYDRAULIC PRESSURE TEST RESULTS -J 1 INTERVAL TESTED (ft) GEOLOGIC DESCRIPTION DURATION PRESSURE OF TEST (min.)(psi) TOTAL HEAD (ft) PERMEABILITY (cm/sec) ---------------------~----------------------------------------------------------------------------- 15-Diroite moderately to or-5 20 49 8.6 x 10-4 closely fractured 6 10 26 1.5 x 10-4 ------- 5.1 x 10-4 117.5 Diorite,moderately to 10 15 38 9.2 x 10-4 126.5 closely fractured 10 30 72 9.0 x 10-4 7 45 107 -31.0 x 10 10 30 72 1.2 x 10-3 --------- 1.0 x 10-3 HD83-46 79.0-Diorite and altered dior-7 17 47 9.3 x 10-4 88.2 ite,closely to intensely 9 19 51 8.5 x 10-4 fractured 4 20 55 8.0 x 10-4 10 20 55 7.9 x 10-4 10 35 89 2.7 x 10-4 10 20 55 3.1 x 10-4 ---_......_--- 6.6 x 10-4 HD83-48 89-Diorite and altered dior-10 20 52 6.2 x 10-5 108 ite,moderately to very 10 30 75 5.9 x 10-5 closely fractured 10 20 52 6.0 x 10-5 ---'"'------ 6.0 x 10-5 1 Modified After Acres American..Inc.,1982 2 Remarks on permafrost are based on Acres Summer 1982 and Rarza-Ebasco Winter 1983 Exploration.Remarks on groundwater are based on th~ 19B3 Winter Exploration. 3 Classification is based on the primary soils types in decreasing ord@r of occurence.Those in parentheses are key secondary types. 4 Thidcness ranges are·based on outcrop exposures and arilled thicknesses. ground water detected. in DR-22. l Gravels are striated and polished. laOlstrine or waterlain till at base groundwater detected. Rounded particles,sorted,relat1v@ly clean.Found okly alon~t~ main thaltomg to date.No permaf'rt)st or groundwater ~l!t:ected.HUd-' 108s of 14 gal/ft over an 85 foot interval in DR-22.! DESCRIPTION Grey brown.gravelly ~and .~o.Sil~:~~d with little- Organ1cs~peat. acti.on. Grey to dark grey silty sand toc1.aY with little angular to subrounded gravel 'and cobbles. occasi.onal boulder.Very dense.'hard.Poorly sorted. Grey stratified sand.gravel and cobbles.Very dense. Grey to dark greyish brown.laminat@ clayey silt to clayey silty sand.Very den5@.hard.Sorted to partly sorted. Olive brown to gt:ey ~rdwn,.silty·.s.#d with little gravel and cobbles to a dlty sallt:l'Y gravel with occasional cobbles and boulders·.COarse fraction subangular to subrounded •Dense .~q:very dense. Poorly sorted. ,::..)'. Dark grey to olive grey,laminated~7isandy silt to silty clay,little or no gravel~·¥ttle to some sand.Very dense.l'oorly sorted.'. ;~ Olive grey to very dark grey.cla:~y silty sand with trace to little gravel to gra~l1y silty or clayey sand.Coar~fractionsubangular to subrounded and includes occasional,cobbles and boUlders~··Very·d:en$e.Pl:ior'lY·sarte'd; Grey brown to olive grey..silty sand'!and san¢.with l1tt¥:it>r;no ~r~vel to sandy g~vel.Coarse £~ace~i9~'i:§\J\~~~to .ro,~~d.··~1;ftb:tlYCl2:*4i,;2:~~ Very dense.Sortedtopardysort:ed~;'..: Olive grey to olive brown.silty':sa.nd, subangular gravel with some sandy;gravel (?). Oxidized and weathered particles..\some cobbles and boulders(?).Very dense.Sor1;i1-d to partly sorted. Olive grey to dark grey.clay to clay~y sand little to no subangular to subrounded oxidil!:ed(?)gravel. Dense.very hard.Poorly sorted. Olive grey.silty sandy gravel to sandy gravel with cobbles and boulders (1)Come fract.ion subangulars to rounded.oxidized.Very dens"'.Sorted. Basal Till TABLE 6-1 WATANA RELICT CHANNa Lacustrine and/or Waterlain Till Alluvium Outwasb Lacustrine and/or Stratified Deposits Basal Till AllU"!'iU1ll Q¥v;~g:tf!Y;.sUty~and w1~hlittle~el tos~drgrav~l.·.with 1Ude·fines.C0.4fse .frael::ion - subangnlar to subrounded trace rounded;some cobbles,partie1es oxidized.Very~~ense.Foody ,,,,I :",,,,..,c ,-_.._....,.,;1.,,l;i?!;~.2;·,:_c·,·....".",;,;"".',;.",.C".;,..<,'"'.; G' J' UNIT TYPE OF DEPOSIT AlB Surficial Deposit Ice Disintegration --- Basal Till --- Alluvium D f Lacustrine E/F OUtwash GRAPHIC snmOL F:;··:~·:i~....a "'./l ••".. [;·~t}/:tii ~~~~ ~ ~~ f~~~~~~~~i CJ I~~~~~~~!: .~ ~:.~.:~:::~~:~~ ,~ii~:~f~~~~il fi~lJi~ m~~~~~~l )-)]])]J 1 -1 I J i 1 J TABLE 6-2 RELI CT CHANNEL DEPTHS TO TOP OF INTERPRETED STRATIGRAPHIC UNITS STRATIGRAPHIC UNITS Boring AlB C M D D'ElF GIG'H I J'J K Bedrock Total Depth--- HD83-1 ---------------0.0 18.0 174.0 194.0 ---243.0 292.0 ---328.a HD83-2 --- --------- ---0.0 ---------20.0 ------77.7 87.0 HD83-3 ------ --- --- ---0.0 14.0 ------------------.87.0 HD83-4 0.0 8.0 --- --- ---17.0 60.0 ------------------138.0 HD83-5 ---_._----------0.0 10 .0 44.0 86.0 115.0 ---------138.0 HD83-6 ---------------0.0 11.0 ---50.5 86.0 --- ---126.5 126.5 HD83-7 ------ --- ------0.0 14.0 61.5 --------- --- --- 82.0 HD83-8 --------- ------0.0 ---51.5 56.0 ---------76.5 78.0 HD83-9 --- ------------0.0 40.0 ------------------110 .0 HD83.49 ---------------0.0 19.0 ------------ ------38.0 HD83-50 ---------------0.0 25.0 --- ---------------119.5 HD83-51 ---------------0.0 30.0 ------------------98.5 FD83-52 ---0.0 ---------8.5 32.0 208.0 229.0 ---310.0 ---320.0 333.0 HD83-53 ---0.0 ---------20.0 30.0 Not Interpretated ---------212.0 ww113 ---0.0 26.0 ---70.0 93.0 143.0 158.0 175.0 ---------206.5 214.5 }1 1 1 1 i I 1 1 I J j J J J )l TABLE 6-3 RELICT CHANNEL -SUMMARY OF MATERIAL CLASSIFICATIONS BY UNITS NUMBER FEET APPROXIMATE APPROXIMATE UNIT MATERIAL FIGURE BORI NG OF OF COEFFICIENCY OF COEFFICIENCY OF GRADE UNIFIED SOILS %OF MAT'L No.2 NO.'s SAMPLES SAMPLES UNIFORMITY CU CURVATURE CU CLASSI F ICAT I ON IN SECTION C Silty Sand D-27 4,52,53 8 27 50.0 1.25 Well SM 100.0 1'11'1-3 M Si Ity Clayey D-16 1'11'1-3 8 13 60.0 .83 Poor SM/SC 100.0 Sand D'Sandy Si It D-34 WW-3 4 4 ------------ML 100.0 E/F Summary of D-21 1,2,4,5,8,9 45 99 --------------100.0 Materials 49-52,WW-3 Sandy Gravel D-22 2,4,9,49,52 10 26 180 .1.0 Well GM 26.3 1'/1'1-3 S i Ity Sand D-23 2,4,9,49,52 35 73 50 1.03 Well SM 73.7 1'11'1-3 G Silty Clay D-35 4-6,49 9 17 -----_....-----CL/CL-ML 100.0 1'11'1-3 G'Si Ity Gravelly D-17 1,3,4,6,9 91 223 ------------SM/SC/GC 100.0 Based on the weighted average gradation of all samples tested. 2 Figures found In Appendix D 1 J 1 I 1 )1 ]1 1 J 1 } TABLE 6-3 Continued RELICT CHANNEL -SUMMARY OF MATERIAL CLASSIFICATIONS BY UNITS NUMBER FEET APPROXIMATE APPROXIMATE UNIT MATERIAL FIGURE BORING OF OF COEFFICIENCY OF COEFFICIENCY OF GRAOE UN t F I ED SO I LS %OF MATIL No.2 NO.'s SAMPLES SAMPLES UNIFORMITY CU CURVATURE CU CLASSI F ICAT I ON IN SECTION H Summary of 0-28 1,3,4,8,52 16 31 ----------------100.0 Materi al s 1'11'1-3 Sandy Gravel 0-29 1,3,5 6 10 42.85 2.67 Well GW-GM 32.3 S (Ity Sand 0-30 1,8,52,1'11'1-3 10 21 12.0 1.33 Well SM 67.7 Summary of 0-24 1,5,6,8,52 22 59 -------- --------100.0 Materials Sandy Gravel 0-25 5,6,52 5 11 128.57 1.28 Well GW-GM 18~7 Silty Sand 0-26 1,5,6,8,52 17 48 50.0 1.45 Well SM 81.3 J'Silty Sand 0-36 2,5,6 18 23 33.3 1.33 Well SM/SM-SC 100.0 J Summary of 0-18 1 8 12 ----------------100.0 Materials Sandy SI It 0-19 1 4 6 ------------SM-SC 50.0 Clay 0-20 1 4 6 -------- ---- CL 50.0 K Summary of 0-31 1 9 10 ----------------100.0 Materials Sandy Gravel 0-32 1 7 7 12.8 4.75 Poor GP-8M 70.0 Silty Sandy D-33 1 2 3 ------------GM 30.0 Gravel FIGURES LOCATION MAP LEGEND "PROPOSED DAM SITES o 20 40 liiiiiiiiiiiii~!!~~!!!!1 SCALE IN M tLES ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT WATANA DEVELOPMENT PROJECT PLAN AND I--__L=-O=-C=,:-:.A TI °N-=---=-=-M.:.:-A,:,;-P==---'-'-'=---I IJW1V1·EIlJIl~fC®AUG..1983 FIGURE SUSfrNA JOiNT VENTURE I-I NOTES I BASE MAP FROM 1978 CORf'S Of:~NG'NEERS J""200'OAMSlTE.TOf'OGRAPflY.· 2.DAY LAYOUT FROM ACRES AMERICAN,INC 1981 b. g ~ .., '" ~""," ~+ ~. -+ 8, ~ ,<:::,,~o/'..,'./)., "( J(J k./ \'-..r~:>'(-..~"((~ /-/ v ~ ~ -+ ___21.aC","",~.__ a §~~~. N 3,2~OPOO -+ N :;,2:3&.o~'n AREA NO.~~~NO, FIGURE 1-2 SUSITNA HYDROELECtRIC PROJECT WATANA DEVELOPMENT SITE PLAN AND VICINITY MAP o lOGO woo rtE'T SCALEr---;;;;;;;! ALASKA POWER AUTHORITY H,.r:u·e~Cfp SI5ITIM.t!I!JTVllOWRI 5--14 5-16 5-'5-.5-. 5-11 ,-, 6-16-'6-' 6-4'-5,-, EXfllORATION MAP TOP OF eEOROCK CROSSECTION A-A CROSSE(;TlVN 6-6 CRosSEcnON C-C TOP OF UNIT S/~' fXPLORATION MAP J ALLUVIUM THICKNESS AND RIVER 13ED CONTOURS TOP OF BEOROCI( MAIN DAM CROSSE-eTtON a-a ADDITIONAL BORINGS UPSTREAM COFFERDAM CROSSECTfON DOWNSTREAM cOFFERPAM CROSSECTloN SUSITNA RIVER RELiCT CHANNELSCD CD 'LVICINITYMAP SUSITNA PROJECT DAMSITE. ~ N j 'f ~V/..I(~R(.o/ ./,>6V''-"';/J'~(.DEVIL )' .),~_~".(("N'ON ',J,'~,~((_~'-DAM -\.'"r (-,,~r\-J \,,),",D,,;,JL~(_Jqfil "-..-\,.'\'".~ F1GlJRE 5-1 N~229.00Q WATANA DEVELOPMENT ,'"e!"'"$C"'LElt[P~ I M3,2.~7.0CO SUSJTNA HYDROELECTRIC PROJECT ALASKA POWER AUTHORITY DAMSITE AREA EXPLORATION PLAN NOTES BASE MAP FROM 1976 CORPS OF ENG1lIEERS 1""200' OtIMSITE TOPOGRAPHY (SHEETS 6 AND 13 OF 26) 2..ALASKA STAff:PLANE COORDINAlf:S rN FEET (ZONE 4) 3.DAM LAYOUT FROM ACRES AMERICAN.INC.,I!)S2 b @"ID9'3-1 HAMMEf!BORING @ DH a~l CORE HOLE ..,G IJ.lCLINm BORING WITH DIP AIIGLE OF 45~ ~~~W~E~~~~~;~~IiNDl~~TI.~~~NA~. E}-0 GROUND RADAR SURvEY LINE Fi83_1 HARZA-E8ASCO/HAROING LAWSON ASSOC. "AI.~~LINE OF SECTION ~GRAVEL BARS MAPPED BY ACRES AMERICAN, INC.,ocr.19132 FY 1983 wINi~R EXPLORATION pROGRAM GEOPHYSICAL SURVEYS SEISMIC REFRACTION SIJRVEY liNE !'M-c 1975 DAMES Eli MOORE '.!t'-(I!:I/~$HANiIION a WILSON 19130-BI WOODWARD-CLYDE CONSULTANTS '::,,1;:_1982 WDODWAAD·ClYDE C()NSIJLrANTS + ,,~j)C //PREVIOUS EXPLORATION "tj!J'--SORE;.HOLES AND TEST PITS .~~~)[)~_/}1978 CORPS OF ENGINEERS ROTARY DRILL BOAING C 1976 cORPS OF ENGtNtEf1S INCt.lNI:::LJ (;Ol<[HOLE d i:,-'_~1960-81 AC~ES AMERICAN,INC.,INCLINED CORE H()(mTP.'l-11 1981 ACRES AMERICAI'f,INC.,BACKHOE TEST PIT ()A;-C--?49B2 ACFiES AMERICAN,INC.,ROTARY/CORE BORING (PNI=:UMATIC PIEZOMETER} r--'' sus/rNA ~~ 5~ ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT I SEISM1C fiEf"RACT!ON-LINES VER1"leAL BOREHOLE. sCAU..Iff FEET LEGEND INGl.INEBB.O'REHO.l.EJ 45'") -~."!;ROUND RADAR SURVEY'LINES ViAtAN"A OE;veLOPMENT RIVER CHANNEL OVERBURDEN =-=C=ONTOUR MAPS I1~~1. r~o~:~~~· -. SURFACE OF RIVER BE:[) CO~TDlJRS REPRfSENT TEMPORARY SJJRF~C~OF FiIVE~eEt'oVElieURC!N CONTOUR IN'IEIiVAl..IS FiVE (51 FT. ---DAM AXIS '-OAM Al(JS I 1 .; CONtOURSiflEPHEEDlT THICKNESS Of OV'ERBURDEN (FT.)ABOVE-TOP Or-BErROCK.CONTOUR INTERVAL [S TWEH-TV I~Ol FEET. ~'5E1sIllIC REfRACTION UNE LENGTH SHOWN La nlE 1tITER~F.TFD BEDROCK PAOFlLE LEHGTlf.SEE APPENDIX A ~~/jI,-,0 +~------~2$'~I § t w ~~g:~:[~~~ 20~~, N3,22.7,oOO ---------::;-~~ N3,:22a.ooo~--- ,I N ],22.6.000 --------+--+-----.+--- I Ig t -1 i 1 1 ·1 1 J I I 1 ....-1 1 -I 1 GRADATION SIZE ANALYSIS u.S.Standard Sieve Openings In Inches U.S.Standard Sieve Numbers Hydrometer/ 12 9 6 2 1 /2 1 3/4 1/2 3/8 4 10 29 40 60 8010140200 210 -._-.,-~.·100100i"-oo~r""_•.LEGEND1\.1'........ ~I\!'\........ro--1"--r".WEIGHTED AVERAGE 9090~[\r""r-.'~.- - -UPPER/LOWER RANGE"-~-i\i--:-;···.,i''."~i\"-""~-,~._-.,. 80';.H~:,~6RAVELLY SAND80I\,I"---....GRAVEL '-\.1\'i\7070,\1\r\1\ I'\"~\60 ..\.c '"~60 .I't'''\,\ti'";II-'."\.">, IJ "\50:II ~.Q~50 ,\1\\l-f'I\.IJ SAND c:.....IJ SANOY GRAVEL Ie\..'\.\\40 lo.c "....;:40 "'\,c"'-IJ.. ~c \IJ r--.....1\30 IJt30Go... I'f\""!"..1'"\'1\ "!\.........f'\2020"I~"t'-o r-......~..... ~1"00..~::....'1010.........--.......~~~ 0 1 I ,- "'"-0.001 05010510.5 0.1 0.05 0.01 0.0051000500100 Grain Size In Hll11meters I GRAVEL ------SAND I FINES IBOULDERSCOBBLESCoaruFineCoarseMediumFineSiltShes,~hY Sh~~ MATER.IAL NO.OF SAMPLES FEET OF SAMPLE %FRACTURE +3/4 %MAT'L IN SECTION ALASKA POW~R AUTHORITY WELL GRADED GRAVEL 2/76 36.7 10 SUSITNA HYDROELECTRIC PROJECTWELLGRADEDSANDYGRAVEL/50 524 /8.9 68 WATANA DEVELOPMENTPOORLYGRADEDGRAVELLY$IW 50 /66 1/.5 2/RIVER CHANNELPOORLYGRADEDSAND6/0 ~.8 /FOUNDATION MATERIALS . GRADATION SUMMARYTOTALS-227 776 -/00 ll.llnlJHM13CO,\DAre I nfivltl ',... ,.,,'NA JOoNJ .,N'.A,AUG 1983 5-'3 ~ l- I I ,I 't UPSTREAM COFFERDAM N 3,229,000 /~-I300--TOPOF aEDROCK CONTOURS (INCLUDES RIVER) _"'-RIVER aoUNDARY CONTOUR INTERVALS VARY AS NOTED. og: \ ) /~~~4' NOTES SCALE IN re.l:." II TOPOGRAPHY FRail 1978 CORP OF ENGINE'RS I"'200'DAMSITE TOPOGRAPHY [SHEETS 8 lll3 OF 2&) 2)8EDROCK CONTOURS AND OUTCROP DATA ~8DVE RIVER aOUNDARY FROM ACRES AMERICA~INC.,1982 3)aeDROCK CONTOURS WITHIN RIvER 8DUNDjlRY FROM 1983 WINTER EXPLORATION PROGRAM. ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT DAMSITE AREA RIVER CHANNEL CONTOUR MAP TOP OF BEDROCK HAIm\'E!lI~1:1t SUSITNiI;.JOlt{TV"UWRE DR;\5~8t.tBER SUSffNA HYDROELECTRIC PROJECT WATANAOEVELOPMENT RIVER CHANNEL DAM AXIS FDN. AREA GEOLOGIC PROFILE B-B ALASKA POWER AUTHORITY ANCHORAGE,ALASKA I AU:;:~COO'AACTNUJ..mER 1 ~9 lum'fUSee SVS!1NAJDJNTV(NTIJREJ APPRO\/Ut ._ TO B9.4 TD 98.2 CIJ.IJI_.6"d BDUld.,:;/=: /'1./• /'-~-" TO 89A ·Pa,tlal Wof"Lo_ C(J//tp/,," Ylaf,tLGu &P 'FflET 9ECTION B-B VIEW LOOKING UPSTREAM TO 127.7 TO 107.7 HD 83-42 a.I462D TD IIB.O HD 83-44 EL.1459.9 ~~:::'':::~Q,/::::j TO 895 HD 83-13 sp HD 83-13 2/$WtJf"Loss af 1/7.5 DJtJrif"f,.,$11 elO$,ly fa mod,ra"ly f'lIdrJ,#t/. hard,sfl'flhl HD 83-10 HD 83-10 o 50 [00 TO 119.5 1380 14"" HD 83-45 EL.1463.6 TO 60.0 DH 83-4 EL.1475.2t---~-/;:0.BOII/d",/~" /">""$"';--~- ../DN IB-4 f.\,..~Grtlll.j7i;Z::~/prtJjle/,(/.J(J'-...Sand c.:....... //f"plan,Df "enon --_ // / // ./// TO 116.6 I:.LEVATION {FI:.ET'J 1 I, 1 1 1 1 1 I 1 J 1 1 )J 1 1 -]j GRADATION SIZE ANALYSIS u.S.Standard Sfeve Openln9s In Inches U.S.Standard Sfeve Humbers Hydrometer, 12 9 6 ~Z I IZ 1 3/4 1/~3/8 4 10 2Q 40 60 801 0140 200 210 100100....~1'1 I I 11111 ,LEGEND I\~1\I I II I 1 II I I I I I II I WEIGHTED AVERAGE ~o.90 ~,'DOWNSTREAM OF f ---UPPER/LDWER RANGE 1\, '\\', 8080\,-. 1\'\\7070\\\1\ 1\\\60 ... I:1t 60 ....1\,~,.. I u0- :a;:;\1\""-UPSTREAM AND 50 Jl :a ::50 I\,~DOWNSTREAM COFFERDAMS l-I'uUPSTREAMOFfcL-II 40 Lo.c \..i:40 ..."•.. II4-' ~C II 1\I'!30 OJt30... "-I~f\I'r-. 1<r'\'"2020 I'"'......I'...r--_-- """:-"-"1010"'~--1"""--l"'"-i=:::~.....-.. 0.00\0 i'0 ["- laO 50 10 ~1 0.5 0.1 0.05 0.01 0.0051000500GrafnSf:e fn Hfllfmeters --- I GRAVEL SAND.I FINES 1BOULDERSCOBBLESCoarseFfneCoarseMedIumFfneISOtShes~1ay She~ I LOCATION NO.OF SAMPLES %FRACTURE +3/4 CLASSIFICATION (USC)ALASKA POWER AUTHORITY . UPSTREAM COFFERDAM 7 30.8 WELL 6R;JPEIl GRAVEL SUSITNA HYDROELECTRIC PROJECT .DOWNSTREAM SHELL /29.9 (~W)WAT ANA'DEVELOPMENT- DOWNsrREAM COFFERDAM'3 37.4 ______RIVER CHANNELUPSTREAMSHELL1039.4 FOUNDA TION GRA VELS .TOTAL 2/WT.AVe.35.8 -G~RAtjATTO~r,r SUMMARY 1I.llllZJHMtl c~I DATE··F/liVRE, ,.",••,ttl••r .,.,...,AUG 1983 ..5 4 1 ")1 '.1 -)-J I 1 I 1 1 GRADATION SIZE ANAL YS!S U.S.Standard Sieve Openings In Inches,U.S.Standard Sieve Numbers Hydrometer 0.001 00.005 I I I I I I I 120 0.01 OF'l. 0.050.1 -++-HI I I I I I II I I I I I I I 170 Trflllrli ,-rllTrl 114'-I-~ I I I I I I II I 10 110 ---'-51 l'0.5 Grain She in Millimeters III I I II I·I I III I I I 100 I 50 I I GRAVEL SAND FINES ---~ COBBLES Coarse Fine Medium Fine Silt Shes ..Flay Sh~ III f\I ['MAIN DAM I 1\11 '~CENTERLINE 60 :: r-..L"~1\.~ ....'"r....;a,~"~\.~I~~.........50 ~ II I I I I I I,.[)(MNSTREAM PORTAL \r\.~UPSTREAM COFFER[J4,"':.40 ; -tXJIINSTREAM aJFFEROAM ~~.DOWNSTIt(AM OF {~ II I I I I I I "'I I II I 'I II I II ~~.','-..'._-u 30 :. 1111 I II I I II III I,,'~I:;').STOJ::"AM II I , I I I I I I I """-."""""....UP -'nc;,M l1l'.!oL...JIII I I I I I I II UPSTREAM PORTAL 1W-l-I---t-J.~---l++H~~irtl-4+H--H-+H-t-+--+Itl+H-H--+---t-iiitH-r---t--r--r--t1itrrH-r-180 12 g 6 ~2 1 12 1 3/4 11 3/8 4 10 20 40 60 801 0140200 270 100 I ,"""~~'"• •LEG END IIIII I I I I LLlI'~f'WEIGHTED AVERAGE 190 I'..~~\.- ---UPPER/LOWER RANGE 100 90 80 70"I ,. ~60...-OJ;a !:50 L "c: i:40.. <: "~30 20 10 0 1000 sao I BOULDERS LOCATION UPSTREAM COFFERDAM MAIN DAM CENTERLINE NO.OF SAMPLESI "/0 FRACTURE +3/4 32 I 25.1 39 I 2aB CLASSIFICATION (USC) WELL GRADED SANDY GRAVEL (GW-GM) ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT 2 I 2/.2 5 I 21.5 40 I 28.0 2~I 23.P_.".... WATANA DEVELOPMENT RIVER CHANNEL· FDN.SANDY GRAVELS GRADATION SUMMARY IlJHUJHWCO I .DAre I /'"~IIRC....,~.....,~.••~.u.,AUG 1983 5:-525.57 DOWNSTREAM PORTAL UPSTREAM POR TAL DOWNSTREAM SHELL DOWNSTREAM COFFERDAM UPSTREAM SHELL TOTAL 150 WT.AV6.24.3 1 j )1 J J 1 ]1 I -1 i GRADATION SIZE ANALYSIS -,.~ u.S.Standard Sieve Openings In Inches U.S.Standard Sieve Numbers Hydrometer.- 12 9 6 2 1 12 1 3/4 II?3/8 4 10 2Q 40 60 801 0140 200 270 100100, f""'-.I'•,I LEGEND1\iOilIli I'"'~...........WEIGHTED AVERAGE 90901\I"~'"---UPPER/LDWER RANGE I'""~",.. 8080i"'",i'f'... "-....DOWNSTREAMIll.7070~COFFERDAMI\. 1'"I\~"-60 ...~60 ~ \~~~.........u-,=-u MAIN DAM \."'~'"=-~~};50 50 .CI CENTERLINE .........~~\L.u..c..i""'"'" ,i:c 40i:40 "~\...,c...\..c ~OJ ""\.~30 30 OJ... a."~I\.I'"I'"1'\.""L-.....I.....20 UPSTREAM COFFERDAM 201'-'~~~ 10 1'1'~~....'UPSTREAM OF fl.10I.......1'...'"'"~"I I I I II I I T I I I--(0-I I I0100501010.5 0.1 0.05 0.01 0.005 0.001 0 1000 500 Grain Size In Millimeters I GRAVEL SAND FINES IBOULDERSCOBBLESCoarseFineCoarseJMediumFineSI1tSizes'.'pay Sh~~ LOCATiON NO.OF SAMPLES ,%FRACTURE +3/4 CLASSIFICATION (USC)ALASKA POWER AUTHORITY ' UPSTREAM COFFERDAM 18 1/.2 POORLY GRADED GRAVELLY SAND SUSITNA HYDROELECTRIC PROJECT -fSP-'SM.)MA IN DAM CENTERLINE /8 -/2.8 , DOWNSTREAM COFFERDAM 1/8.6 WATANA DEVELOPMENT UPSTREAM SHELL 3 15.6 .,RIVER CHANNEL TOTAL 50 wr.Ave.=Il5 FDN.GRAVELLY SANDS GRADATION SUMMARY 11.Q1UJl'(Mila:~1 DArt FlGIJRC '""'~'...,.r .,.,."'AUG 1983 5-6 ]I 1 I I 1 1 1 1 ]]J J 1 I GRADATION SIZE ANALYSIS I u.S.Standard Sieve Openings In Inches U.S.Standard Sieve Numbers Hydrometer.- \2 9 6 2 1 12 1 3/4 II 3/B 4 10 20 40 60 801 0140 200 210 , 100100,..LEGEND r"1-0 ~r---WEIGHTED AVERAGE 9090,,""I"'"1'"---UPPER/LOWER RANGE I'I"-".,8080""""'"","'Iiiii ~, ..... '""'"7070"'''1\I\. UPSTREAM ,DOWNSTREAM 60 ..-..c~60 \Dl COFFERDAM ,COFFERDAM -Dl ..-;II..~;II I 50 >,};50 ,s:) .~\I. II..C..,-I: 40 .... i:40 ~.. 1\.c....,I:e.,.,~, ~30 30 II......\~.\ \.\\"2020\\~roo. 10 r\'~10".... 0 0.001 0 100 SO .10 5 1 0.5 0.\0.05 0.01 0.0051000500GrainSheinMillimeters, I I GRAVEL SAND fiNES 1BOULDERSCOBBLESICoarseFineCoarseMediumIFineS1\t Shes 'pay Sh~~ LOCATION NO~OF SAMPLES %FRACTURE +3/4 'CLASSIFICATION (USC)ALASKA POWER AUTHORITY UPSTREAM COFFERDAM 4 3.7 POORLY r;RADED SAND SUSITNA HYDROELECTRIC PROJECTDOWNSTREAM'COFFERDAM 2 3.8 (SP -SM) T:OTAL6 WT.AVG.3.7 WATANA DEVELOPMENT _.-RIVER CHANNEL FOUNDATION SANDS GRADATION SUMMARY II~W.(M13CO,1 DATe.Fl~IIRC 1vI,'N',"".,,'N'UN,AUG 1983 5-7 1"D 58.0 HD 83-40 ELEv.:14706 ROCK RI!IIV~H«:tww;yS«t/. PNt'II! Gra{n Sit.-P;m:enl By welg/d o~SOIL 'lCWf1 Om",~z, .;and.dis'fr/lJuthn .""-"i "dtttermirMd lJy:~••;'~',•..•FIn••1 UDS~"Ane~ 10 2JO 30 40 OomPlO:l~--' -petJ1r 'fQ/wIs/ltWn inpt1f",,/I'$is LEGEND TO 57.5 ~.D;()rlt'~tl/l."'r1 PttntJ«JbilibSC~t""""_1>'&'" Pe_Df/ify$t:t1'- ko-t;tiI/.$w %tt· a.!1t mama 01-' 10ft mtlfWllg (Iyp.)t-eJr10.02 UllifiMf Sitlls-CloS$/Y/#f1liDn Permf1/1bilfly 78~1 ."typ.)kt=2.0 1t10- I Up~~~r}.;~ci~TAL----------I (9Elj Olorl1.,~H,-hifJ aJltJndfll1d lNIa!/J/!""/ltIrd,$tro", ~:7;%:Jyf:::/~od "10 . td TO 94.5 HD 83-38 ELEV.1462.7 rE"'"IDE :~ HD83-37 (LEv.1462.5 IQ TO 155.0 TO 126.5 DH 83-3 ELEV.1460.7 TO 43.6 k.l.lXltJ"3 TO 715 l--oJ;,~m'E~/~:~--1 HD 83-36 ELEV.1456.81"r -r IQ 20 J-.--L HO 83-35 ELEv.1458.4 TO 57.8 H083-32 ELEV.1454.0HD83-33 ELE\',1453.2 J oo:~gtk~iMGP&rrAL I TO 32..4 HO 83-34 ELE'l i454.9 1;,,30 TO 166.0 I ~:ft~~~~1~ I.FOR LOCATION OF SEl:FIGURE 5-' ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT W1\1"ANA OEVElOPMElIT RIVER CHANNEL MISCELLANEOUS BORINGS ;:!~.;~!!!2 GRADATION SIZE ANAL VSIS u.S.Standard Steve opentngs In Jnches U.S.Standard Steve Numbers Hydrometer.- 12 g 6 2 1 /2 1 3/4 1/3/B 4 10 20 40 60 BO 1 0140200 270 100100•I ~t--:• \~~..9090~~ 80 \r\"80i\"~7070\f\,'\1\.60 .. J:.~60 ...r\~1\-II...:aa; ">0;II GRAVEl f\GRAVELLY SAND-50 ,Q}:50 '"L.\.II1\0:;L.l-"\f"':i:II r\I: 40i:40 -"...,,c...IIC~II "-3D IIt300-....1\,~....i'... SANOY GRAVEL -I.........""'"-2020"".......... ..........r---..... ~i""~--!-o.""-1010 f-""""-I--t- O 0.001 01005010S10.5 0.1 0.05 0.01 0.0051000500 I Gratn She tn Ht11tnleters r GRAVEL SAND FINES I --BOULDERS COBBLES COa rse Ftne Coarse Medium Ft ne Stl t Shes ~hy stze~ MATERIAL NO.OF SAMPLES FEET OF SAMPLE 0/0 FRACTURE +3/4 %MAT'L IN SECTION ALASKA POWER AUTHORITY WELL SRADED GRAVEL /0 4/39.4 28 SUSITNA HYDROELECTRIC PROJECTWELLGRADEDSANOYGRAVEL259723.5 66 " WELL GRAOEO GRAVELLY SAND .'$9 '/5.6 6 WATANA DEVELOPMENT RIVER CHANNEL TOTALS 38 /47 -/00 AREA U/S OF DAM AXIS GRADA liON SUMMARY IlMllJHMtlCO,1 DAr£.1'..'IiI/if{ Iv"""JO,N'Y'NMr AUG 1983 '",5-12 ..! ]i )J --]1 -1 I 1 -1 -1 1 ]1 1 I I _... GRADATION SIZE ANALYSIS / .".- U.S.Standard Sieve Openings In Inches U.S.Standard Sieve Numbers Hydrometer " 12 9 6 2 1 12 1 3/4 11 3/B 4 10 20 40 60 BO 1 0140 200 210 100100•"R I •I LEGEND1:.., 1\,""WEIGHTED AVERAGE 9090''\-----UPPER/LOWER RANGE \8080 "1\ "~,7070~\ ~l\,60 ...z:~60 ~.,.-II.,. :-0;~~:Jl 50~50 ~...II.....II I\~i:.. 40i:40 -...~t'oo ,c:...IIC ~........~II 30 II~30 '-......'i'oo.,-.... - """~................2020................~I'~r-........... ~.........-.1010:"-r-1- a 0,001 0100SO10S10.5 0.1 0.05 0.01 0.0051000sao Grain Size In Millimeters r 1 GRAVEL I SAND 1 FlH£s 1BOULDERSCOBBLESrCoarseFineCoarseMediumIFine1511tShes~lay shesl LOCATION BORING NO.NO.OF SAMPLES %FRACTURE +3/4"CLASSIFICATION (U s C)ALASKA POWER AUTHORITY OOWNsrREAM HO 83-36 2 21.2 WELL GRAOEO SANOY GRAVEL. SUSlrNA HYDROELECTRIC PROJECTSHELL(GW-GM), "WATANA DEVELOPMENT RIVER CHANNEL COMMENT:6 OF SAMPLE AREA DIS OF DAM AXIS iSANDY GRA VEL GRAQ Il.llnIJHMI1C~1 DArE ~I FlulJlI£ 'OulNA lOll".''''''"'AUG 1983 5-13 1 I ]I J 1 1 »1 1 i 1 ) GRADATION SIZE ANALYSIS u.S.Standard Sieve OpenIngs In In~hes U.S.Standard Sieve Numbers Hydrometer ~ 12 9 6 . 2 1 "/2 1 3/4 11 3/8 4 10 20 40 60 80 1 0140200 210 -100100'"....I , "'"K",,"9090I\.r\. ~...._.. 8080\ '\ I~III 7070\I'. ~"'" ,60 ..,£!~60 l'\.'"-'""...-SANOY ;II.. GRAVELLY >-.;II ~50 .Q~50 GRAVEL """""SAND l-f'~ul-e..1\~~c 40i:40 '\~",e..uc "'~u 30 u~30 ................"......~~2020ro-.....1"\100.......~10 10r--;;;:: 0 0,001°500 100 50 10 I 0.5 0.1 0.05 0.01 0.0051000GrainSizeinMIllimetersIBOULDERSGRAVELISANDF1NES 1COBBLESCoarseFineCoarseMedIumFineSl1tShes~lay Sh~~ MATE~IAL NO.OF SAMPLES FEET OF SAMPLE %FRACTURE +3/4 %MAT'L IN SECTION ALASKA POWER AUTHORITY WELL GRADED SANOY G'MVEJ 39 148 20.8 61 SUSITNA HYDROELECTRIC PROJECTPOORLYGRADEDGRAVELLYSAND/8 12 12.8 33 WATANA DEVELOPMENT TOTALS 57 220 -100 RIVER CHANNEL. DAM AXIS FDN AREA GRADATION SUMMARY IUnlJHMl:JC~1 ~Arc ,I "fliRt ,.",.......d ."""..AUG 1983 5-10 RQO/C,,"~_t. ~~- ~!50 ""ROCK LEGEND p~'::::::::::.SCt1It!.G-rrilt$iM-~/r:tMl!JyWtJitJfrf --~Ue-,-""-"",,,,,,·SOIL(/)1J.)k'2"~~';;;/l =t::a.(Jnifi~d So[/s II ....-:1;'%;FinB *'lJm~f¥d by Clt/t;slficolltJl1.,,'<"""_,"_<,'-".lLJlJ_SI,~eA1U1Iy#$ 10 20 30 4O-GommtlSI;, Deplh morJren of _ IOftiflTerw/$ P-rm:::/,if$ ""')k,2.O''')' HD83-23 EL 14Sa0 HO 83-41 EL.147l9 >{ '....,......j "Gra••II)'flllld / "andl ___5"./.;.ra,Sutldy 'fITlIII"/ ~-~--T 'f /<:::;..~"--~'""y/~. 'f:J!lUi7F37-....------"<.y TO IM5 Pl~~~:.,I1$;,,~;:n:r':r:::,i~.,.s TO 87.0 10107.3 ~ y ,f[J;I I If FEET SEctION C-C ViEW'LOOKING UPSTREAM HD83-22 EU'<;~6 TO 86.5 ------------TO 76.5 (REFUSAL) TO 98.0 to 91.0 TO 77,5 B.drDck t:0 83-18 HO 83-17 OH 83-1 HO 83-19 HD 83-20 HO 83-21 EL 1465.7 EL 14644 EL 1464.0 EL 1463 5 El 14649:EL 1467.7 Rlr.r $and -'!"!t ~\-~~/:~=:=::::::::=:::..~-~''"'::~:f:;;;:;,;--,"J,t-----~-'--=~~~~~f.~~~~l':-::~=!':::::.~~~-.I-~,~= \6rar,1 ------X------------~------~~dJtB(Juld.r$~!!.!!.....!'!.!!-.".-J BIJou1n,ZDn,6rtt".'Bar f:~,!!:>.~.."~ .............Sand,)' Tc390 ELEVATION (FEEll 14eo <P ALASKA POWER AUTI-IORITY RIVERA CHANNEL U/S COFFER DAM FDN. GEOLOGIC PROFILE CIC SUSITNA HYDROELECTRIC PROJECT '---..... TO 107.3 TO 86.5 NOTE TO 76.5 (lUfu$lI/ill alNrId ,m"ile) HD 83-20 I.FOR LOCATION OF PROFILE SEE FIGURE 5-1 DioTiI.~aln,.lII, rfi:~:::!r:r!/r~m~'=!r Dio,il",lIghlly IJlffMd. hard;.'nmg TO 980 HO 83-19 ~'::'::IMIW/, hard,slnmg "Oieri/"DlIe.d. gronultlr,IFiolJl•• clflY_Y $2£)"0 SO' R.t;.(J~tI,.tld "bbl.,and"oar••,rav.l;land ondsillillwad.,1;1;nmlng sQlld nportld /Iy drill. ~52.0 ff. ~O-2.0'dlom,16rbCHIId., ~d"'T8.0' ~tNJIJb_,CQD"",rfJV'.'t«fWtlred~fintswallll'dowtiy 75.0-1.0'diam,ter IJtJuIoW 15.5"052,0' BOIIldl'n,t:QIJIJ/n and coar$',rtw,i Max.siz,"CDVlrl'd OB' mDsl /I'Iol.nOi 02'-0.4 rar;.d Illlu"rJ9i.~ M/!Jmunud 10 'ound6d "t:bt'I'.tI Rl'tXWl'ry ~tlDM TD91.0 DH B3-1 IrJ O;oril" t/ery hard,$lrong TO 77.5 HD83-17 ~'::::IIr"MJI liard,"ron, HO 83·18 !OJ 1420.. 5::14 I I 1 1 1 ~-J 1 1 ..•)1 i I 1 GRADATION SIZE ANAL VSIS u.S.Standard Sieve Openings In Inches U.S.Standard Steve Numbers Hydrometer"' IZ 9 6 2 I 12 1 3/4 1/3/8 4 10 20 40 60 801 0140200 270 100100r-r--r-t-o , 'i~""r-......""9090, to-.. , t\.. "1\"-r---. ""'"8080r---.....1\1\.,... 70 70 " \.r....r-. "1'"1\.60 .. .I:~60 ...i\I'"...Dl ..-:-..\r'\"-...;II GRAVELLY SAND 50250GRAVEL-'..a \"..r-\....--.c:..I ,111111111111 1\1 H-I~+I-+-H--~--+H+!j:;:c 40~40 ,..I I I I III I I II I I ,~"-,c:....c -~..1""'-t 30 1\.~30 ..SANDY GRAVEL SAND ...- I'...I'............\~-1\1'...\2020....."",~I'...~, "'"~-,r""'-IO10..........--~ I 0.001 00100501010.5 0.1 0.05 0.01 0.0051000500"Gratn She tn Hl11tPleters I I GllAVEL SAND FINES -'BOULOERS COBBLES Coarse FIne Coarse I MedIum Fine Silt Shes pay Sh,~ MATERIAL NO.OF SAMPLES FEET OF SAMPLE %FRACTURE +3/4 %MAT'L IN SECTION ALASKA POWER AUTHORITY WELL GRADEO GRAVEL .,24 30.8 13 WELL GRADED SANOY GRAVEL 32 99 25.I 57 SUSITNA HYDROELECTRIC'PROJECT POORLY GRADEO GRAVE/.i.Y SA\I 18 47 11.2 26 .WAT ANA DEVELOPMENT, POORLY GRADED SAND 4 8 3.7 4 RIV'ER CHANNEL U/S COFFERDAM FON. TOTALS 6//78 -100 GRADATION SUMMARY t1~n.uHMU4::0,1 .DArE ttliIJIIE . ,...,••,,*,N'•••,••,AUG 1983 5-15 HD 83-27 HD 83-28 EL 1453.7 EL.1453.6 TO 98.5 HD83-29 ELI453B TO 96.0 TO 104.3 'Ditwil#,~IIItWItlIh."'d, htI'481nJlJl TO 95.9 HD83-25 HD 83-30 EL1453.8 Sand HD83-25 ELI454.4 TO 95.9 TO 82.9 HD 83-31 '~20 30 l' 6,a~.'ly ...., 1460 7082.9 ~~~~~---\-----yt____~~~:7 HD 83-31 \ ----~_EL 14562 ------>- \Sand¥a;;a..'/"/~""--~-----T .-.-iT "S'Qr.lI~san't./~ '-..'/'',,-//"",'/ "TOlREFUSAL! ND _4ft._J-cfod........ ':.!J~-:~.16 pIa".Df --,__:.:.=...r"................. ?~~:;--- --.§"f/fl ~/),,~o r..,..""",,o-.... 44;11",% ~.........".,;~.J TO 104<3 NOTES I.FOR LOCATIOIl OF PROFILE SEE_FiGURE 5-1. 2.UPPER PROFILE IS TRUE SCALE (1l0 VERTICAL OR HORIZOl'ITAL EXAGGERATIOlll.LOWER PROflLE IS EXPANDED WITH 110 HORIZONTAL SCALE. ALASKA POVVERAUTHORITY SUSlTNAHVOI'lOELECTRIC PROJECT RIVf=RCHANNEt DIS COFFER DAM FDN. GEOLOGIC PROFILE A-A 5~i6 )1 -1 1 J J -··1 1 J 1 1 I I ] GRADATION SIZE ANALYSIS u.S.Standard Sieve Openings In Inches U.S.Standard Sieve Numbers Hydrometer.- lZ 9 6 2 1 12 1 3/4 1/3/8 4 10 20 40 60 801 0140200 270 100100,....•I •~r-..t--."" ~~I"'"'"-..;;;"'"9090~'"'I"- "'"i\i\'"-...~8080"r"....l\\.,"'"7070i\\ \.I\.1\\60 .. .If:~60 ...~I\.-...1\II~GRAVELLY SAND :-:-GRAVEL \."\50 };;;50 "'r'\:~I I III I I I I I II I I ~ II..0::II /rm -I 1\",·11 II I I r:::0:: 40i:40 "'~-n1J,-,-,-I I I 1 I I ..I I II III I [II I I 1\0::....II0::-~II !\ , """II~30 SAND -30 .....SANDY GRAVEL "r-....."............,. I',.......,'-\.2020""""~~""-...... -......:100....'-...::t:--....'1010-~"'"'10- 0 0.001 0 1000 500 100 50 •10 5 1 O.S 0.1 0.05 0.0\0.005 Grain Size In Millimeters r BOULDERS I GRAVEL SAND FINES -, COBBLES r Coarse Fine Coarse Medium Fine Silt Shes l:hy Slze~ -MATERIAL NO.OF SAMPLES FEET OF SAMPLE %FRACTURE +3/4 %MAT'L IN SECTION ALASKA POWER AUTHORITY WELL GRADED riRAVEL 3 8 37.4 4 WELL GRADED SANOY GRAVEL 40 /38 28.0 75 SUSITNA HYDROELECTRIC PROJECT POORLY riRAOED GiA~LLY SWl /I 38 8.6 20 WATANA DEVELOPMENT POORLY GRADED SAND 2 2 3.8 /RIVER CHANNEL DIS COFFERDAM FDN. TOTALS 56 /86 -/00 GRADATION SUMMARY IIJlnuHMtl'~1 .'WE sl''''IJIt£• Mo',A .<I,.'.,"V"AUG 1983 5-17 ~l I J 1 I -I ~1 1 I 1 I 1 I 1 I GRADATION SIZE ANALYSIS u.S.Standard Sieve Openings In Inches U.S.Standard Sieve Numbers Hydrometer~ 1Z 9 6 2 lIZ 1 3/4 1/3/B 4 10 20 40 60 801 0140 200 270 100100 1'0 "",l""- I LEGEND ~.['\"WEIGHTED AVERAGE 9090I'I~- - - -UPPER/LOWER RANGE 1\1\1\8080,1\\ ,,, 70701',1\",\,...~60 60 ..c-go~\~-.,. II&;;II ;II '\1\50 :;};50 ,,.. IILCIIl\i:c 40i:40 -..r--.,.c.."-IIC~""~30 I\.........30 II... "-I"""I......., I' 20 '.,.......20'...~"'I ..... 10 .......,t'"-....101"--0 I-.'~.I"-...-1---1--.....I-n 0.001 00 1000 500 100 50 10 5 •0.5 D••0.05 0.01 0.005 Grain She in Hillimeters I GRAVEL SAND FINES IBOULDERSCOBBLESCoarseFIneCoarseIMedIumIFineStltSizes.~1ay Sh~~ _. LOCATION BORING NO.NO.OF SAMPLES %FRACTURE +3,I4 1i CLASSI FICATlON lU S C)ALASKA POWER AUTHORITY UPSTREAM HD83-7 25.5 WELL GRADED SANDY GRAVEL (GW) SUSITNA HYDROELECTRIC PROJECTPORTAL/4-/6 AREA WATANA DEVELOPMENT RIVER CHANNEL COMMENT:20'OF SAMPLES U/S PORTAL AREA ;SANDY GRAVEL GRADATION 1l.all1JHM\3iC~1 flArE I "IiVReJul.,.....,.".""'UH AUG 1983 .5-18 1 -I 1 -1 J -I -J J I -1 -I )1 I -I ---1 -1 I GRADATiON SIZE ANAL VSIS u.S.Standard Sieve Openings In Inches U.S,Standard Sieve Numbers Hydrometer, 12 9 6 2 1 12 1 3/4 11 3/B 4 10 29 40 60 801 0140 200 210 .100100("'Ill ~ ~9090\\ 1\8080\ 70 ~1\70~\-,,.. ~60 60 -a.1\........ ;;lO...-'\1\":;;;JO GRAVEL SANDY GRAVEL 50:;;50 , L.1\.. "L. I' ---,-'-;:.. " r: 40;:40 -..1\.0:..1\"0::~.."-30 ..~30 ...I ...~'"I t\,"'-2020"""t-................1"'iO"",I-10 --..10 '---0 0,001 01005010510.5 0.1 0.05 0,01 0.0051000500GrainSizeInMillimeters r I GRAVEL SAND -,FINES IBOULDERSCOBBLESrCoarseFineCoarseMedIumFineISiltShes~hy S1z~~ -~". MATE~IAL NO.OF SAMPLES FEET OF SAMPLE %FRACTURE +3/4 %MAT'l IN SECTION A~SKA POWER AUTHORITY WELL GRADED GRAVEL I 3 29.9 /6 WELL GRADED SANDY GRAVEL 5 16 21.5 84 SUSITNA HYDROELECTRIC PROJECT WATANA DEVELOPMENT . TOTALS 6 19 -100 .RIVER CHANNEL·.DIS PORTAL AREA GRADATION SUMMARY' ff~UlJl'(M13iCO,1 OAr£II ''''Jill' M"N'J'J'"VlN'."AUG 1983 5-19 FIGURE 6-1 DATE CONTRACT NUMBER ANCHORAGE,ALASKA AUGUST 1983 sus/rNA JOfNT VENTURE APPROVED SUSITNA HYDROELECTRIC PROJECT ALASKA POWER AUTHORITY WATANA DEVELOPMENT 400 BOO ! NOTES I.BASE MAP FROM 1978 CORPS OF ENGINEERS-I"-200' DAMSITE TOPOGRAPHY,SHEETS 7-9,12-15,17-20 OF 26 2.ALASKA STATE PLANE COORDINATES IN FEET (ZONE 4) T RELICT CHANNEL EXPLORATION PLAN SCALE IN FEET GEOPHYSICAL SURVEYS SEISMIC REFRACTION SURVEY LINE 1975 DAMES a MOORE 1978 SHANNON a WILSON,INC. 1980-81 WOODWARD-CLYDE CONSULTANTS 1982 WOODWARD -CLYDE CONSULTANTS PREVIOUS EXPLORATION BOREHOLES AND TEST PITS 197B CORPS OF ENGINEERS ROTARY DRILL BORING 197B CORPS OF ENGINEERS AUGER BORING 19BO ACRES AMERICAN,INC.,AUGER BORING 1982 ACRES AMERICAN,INC.,AUGERfROTARYfCORE BORING 1978 CORPS OF ENGINEERS BACKHOE TEST PIT 1980 ACRES AMERICAN,INC.,BULK SAMPLE LOCATION 1982 ACRES AMERICAN,INC.,BULK SAMPLE LOCATION INSTRUMENTATJON PNUEMATIC PIEZOMETER P PIPE PIEZOMETER THERMISTOR THERMAL PROBE PIPE FY 1983 WINTER EXPLORATION PROGRAM o HD83-2 HAMMER BORING tV WW-3 WATER WELL BORINGoDHB3-2 CORE HOL E LINE OF PROFILE CANNOT SCAN LARGE MAP ~\100-------TOP OF BEDROCK,CONTOUR INTERVAL 1lO FEET (;)HO 83'6 HAMNER BORING (;)WW-3 BEOROCK OUTCROP.UNOIFFERENTIATEO LEGEND SURFACE CONTOURS 2.BASE NAP _1978 CORPS OF ENGINEERSr·200'DANS ITE TOFOGRAPIIY. 3.PREVIOUS.BORINGS 8T CORPS OF ENGINEERS, 1918 ANO ACRe)AMERICAN,INC.,181l()-B2. 4.PREVIOUS SEISIIIC REFRACTION SURVEY1i::~J'::~:I1~:~~~T'm'~W~ CLYDE CONSULTANTS,1880-82. So DETAILED TOP OF BEOROCK IN DANSITE AREA SHOWN IN FIGURE s-a. 6.DAN LAYOUT FROM ACRES AMERICAN,INC., 1882. PREVIOUS BORING Pl'lEVIOUS SElSMICREFRM:T10N SURVEY LI"E NOTES I.NOOIRED AFTER ACRES AMERICAN,INC., 1882.SEE FIGURE 6.7 •AII-o-Z6 .__-2Z0C'------ ~ , ill ~~ -~ ------------...C .....··-·~"----....._--- rJ 3,;~4Q,O()') N :'J,Z3ZP(){) ?~2Opo FE"ET ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT WATANA DEVELOPMENT RELICT CHANNEL CONTOUR MAP TOP OF BEDROCK !;~,~!!! lffGURi 6-2 6-3 22C1.O WATANA DEVELOPMENT SUSITNA HYDROELECTRIC PROJECT ALASKA POWER AUTHORITY NOTES RELICT CHANNEL GEOLOGIC PROFILE A-A HO 83-6 I.)SEE TABLE 1';.1 FOR STRAnGRAPHIC DESCRIPTION OF UNITS A THRU IC 2.J SEE BORING lOGS FOR DESCR(PTJOHS OF COBBLES AND BOULDERS IN GLACIAL Q£POSITS AND FOR COMPLETE SOIL AND ROCK DESCRIPTlONS. I ////r ~/~ 8 {/51IJ2L/11/T} Blows/roo' TO 97 ~~::c~~ jr IJi'I 10Ia'0/1l!' Eff 'fJ!,,:/ \ \ \ \ AHO-a6 .., tJI/ TD 109.9 -~~~ I GC '} ,,/Flsc ''l< D..<rt~i~·;;;;rs::':~-B= D,I,Ir11tiMd by l' Lob Sl8118 Anoly5U Fine'_====n LEGEI'!D C 1 8M S.OIO.iCU.,:],IClo~sjfication ~G [)rpM Ml1rk_rs o/20ft.i/lIf!n'i1ls .I Predomif/fJnl Unified SoH CI..,ifl""••D"Cripilo.-GMI Wfl'~r during dnJlill(f-J--...,...l TDIOO.. TO 211 ,WJf§j,~~~~;j ~I Ir0Il3 - 53 TO 3:29 HO 83-52 EL.2249.1 TO 333 BR WW-'3 EL.2267' 'I 27'4'JO 6<JO "JO KXjO FEET HORIZONTAL SCALE 77 -------_Blllrot;k Sutf(JU fmllt eoJtfOuF.llnitnaf"d 'I 200 400 600 aqo ,;::'Am",...,I.~(1982)~" HOR'Z~A1.SCALE / 'N n /II HOe;-52 HOl3-1 I I··, G' II 'I,P"-j ~~~~ BRI----.J TD 2'4.~ 2260 ,..J ELEVATION (FEET) ELEVATION (FEET) FIGURE8-4 TO 12~ HD83-6 WATANA DEVELOPMENT SUSITNA HYDROElECTRIC PROJECT ALASKA POWER AUTHORITY RELICT CHANNEL GEOLOGIC PROFILE B-B PROFILE LOCATION PLAN J' TO 38 HD 83-49 r--S.CTIOl{C-C ") NOTES HD 83-9 TDIIO G' J.)SEE TABLE 6.1 FOR STAATIGRAPAIC DESCRIPTION Of UNITS A THRU K. 2.)SEE BoRING LOGS FOR DESr:RIFT'tONS OF eaSelES AND BOULDERS IN GLACIAL DEPOSITS AND FOR COMPLETE SOIL AND ROCK DESCRIPTIONS. DR-22 TO 493.6 G' ./F TD98.5 HD 83-51 tP I--~-l :::'::~::::c Fool LEGE/'D Pr!~~O::/53;weigh' ~'>-...N W PLLL....-,N.SIOnd.,dP,....'!/riJ/iQfI TO 4936Ir~S//81()w$/f(Ja/'Il'W~MtJis/l,/rt COII.,en/[f:.r~rn/) 181'24,PL-Plas/ICLfml/(pNCen/) LL~Lit1lJldLiml/IpiJI'(;eh/) TO 94 HD 83-4 (j110ID9'C Unit Cloni/1CII/Jon ---G Wo/tlr durin9 drillIng o/;;'/:,'::;:"~;-- Prtll/(IJ1linant (Jnilld"Boll Classi/u;allon [)l1sCflp!ian---rGM TO 119.5 G' HORIZONTAL SCALE H 10 V"T a'WI "on ~d [Sand· (frolnShe (jrol'~/- Q zoo 4qO 690 850 1090 FEEl Otl/tumi"",d bl-,l ~lLobSitlveAnolysi!$F'h6$--1-+- TO 138 ,I' HD83-SO HD 83-5 ?>PO "'I""I""'JO ""l"FEH HORiZONTAL SCALE +t ./F 2:240 2080 ElEVATrON (fEE'n 2000 ElEVATIO..(FEET) 6~5 AH-D27 WATANA DEVELOPMENT TO 195 c I~ G I~ o i~, z. El'F SUSITNA HYDROELECmlC PROJECT ALASKA POWER AUTHORITY RELICT CHANNEL GEOLOGIC PROFILE C-C ,PROFILE LOCATION PLAN I M41N'i.L~ELlCrCHANNEL '-'--t~--..---\ :~_.~ S«:OND.J· BELlGT i eN'NNE!! I AH-D5 1fAIlA·£MICI $vs,rNA JOINf VENTURE NOTES TO 46.3 c~JL. 8M E/F 8M CL , iii .. ., 2.}SEE TABLE 6.\FOR STRATIGRAPHIC OESCR'PTI~OF"UWITS A THRU It.. 3J SEE BORING LOGS FOR OESCRIPTtONS OF C.BBLES A.ND =sQULlJEFcS IN liLAf:IAl OEPO.:i1T5 AND FeR COMPLETE SOiL ANO ROCK £,ESCfUPTIONS.,TO 328 HD 83-1 K TO 110 HD83-9 LEGEND I I !N!WIPl!Llr--r N~};~':J'Jf,:':~I-~:ran W=Mi.Jlsfl;l'eCCKI'ellf(~rc.n/} PL~PJtlSI'"Limi!/.tJercenfJ Ml: DIORITE TO 1515 CL CH G' c I~ 8R AH-D20 El'FI8M 9 29"490 "'i'".qo 10'1" HORIZONTAL SCALE H 2v~T 9 2QO "90 "S'""90 "",0 FEET HORI20NTAL SCALE H 10 VI TO 82 HO 83-7 Ed ELEVATION (FEETl ELEVATION {FEET} --1 -1 i 1 1 1 1 I 1 )1 - GRADATION SIZE ANALYSIS u.S.Standard Sieve Openings In Inches U.S.Standard Steve Humbers Hydrometer 12 9 6 3 2 1112 1 3/4 1/23/8 4 10 20 40 60 80100140200 270 100100f.:.t-.."~\LEGENDr--.~~r--...WEIGHTED AVERAGE 901\90 --~\- - -UPPER/LDWER RANGE'\ r\--....:r-.r-io-.\8080r..........r--.....--.f"'-...,..I'".l'.I"'-""f"....~kV 7070r-.... ~""'......... I"'---r--........................r................,./60 .. .&:~60 ...r-..r--..~..-..... :a... I'....r...I'...50 >,:a .Q~50 f't'-...'.. '-.. 0:.. ,,""'-....-..1\ 40 ....'"1:40 "...G/.....-~.....'M .c II.. ~C --.--'II '....I--30 OJu c..:30 ~--"...... ~. 1>0:"2020..~--1010 0 0.00\01005010510.5 0.1 0.05 0.01 0.0051000500 Grain Size In Millimeters I I GRAVEL I SAND I FINES IBOULDERSCOBBLESICoarseIFineICoarseMediumFineISiltSliesJ:hy SIz~~ UNIT I MATERIAL NO.OF SAMPLES FEET OF SAMPL E %MAT'l IN SECTION AlJ\SKA POWER AUTHORITY M SILTY SAND I (SM/SC)8 -13 100 SUSITNA HYDROELECTRIC PROJECT 0'SILTY GR AVELLY SAND,(So/So/BC)91 233 100 SANOY SILT,(SAI/SC)4 6 50 WATANA DEVELOPMENTtT RELICT CHANNEL;r CLAY.(eL)'9 6 50 .BASAL TILL '.. GRADA TION SUMMARY Il.ll/llA·£Mild:0,I DAre "livRe ,..",••-",.or ".'''.r AUG 1983 6-7. 1 1 ~J 1 J 1 1 -J 1 1 J ]I ] GRADATION SIZE ANALYSIS u.S.Standard SIeve Openings In Inches U.S.Standard SIeve Numbers Hydrometer 12 9 6 3 2 11/2 1 3/4 1/2 3/8 4 10 20 40 60 80100140200 270·--100100,I"'........,I-t...:..,LEGEND """~ ~"'-.........i'..WEIGHTED AVERAGE 9090\'~'\I'r-.\- - -UPPER/LDWER RANGE,~\r-....\8080 1\"", \...........7070\......."-. \~\"-r-...1""60 ...\.£co~60 \"...../"'-....1\uDo :a0:;"......1\50 >,:a ".Q~50 1\'\t--t'-[\l- II CL '\.~i:II I''0 40 c ...i:40 H .\c\f'..~. II... ~r: \II ,1\"-..I 30 IIUI...t 30 ,\I\.... "-""'--2020f'""HK....~""I'........ .......-...-...............10r--..r.....10 I I .""~r-I---~ I '"';1- 0.001 0~0 10 5 1 0.5 0.1 0.05 0.01 0.005100050010050 GraIn Si2e In Millimeters I I GRAVEL I SAND I FINES IBOULDERSCOBBLESICoarseIFIneICoarseMedIumFIneISOtShes~1ay Sh~~ UNIT MATERIAL NO.OF SAMPLES FEET OF SAMPLE %MAT'L IN SECTION ALASKA POWER AUTHORITY . SANDY GRAVEL,(GW/GM)6 /0 ~ZH SUSfTNA HYDROELECTRIC PROJECT H SilTY SANDI (SM)10 2/68 WATANA DEVELOPMENTSANDYGRAVEL,(GP/uMJ iK7770RELICTCHANNELKSILTYSANOY,(GM J 2 3 30 ALLUVIUM GRADA TION SUMMARY IlMUJHMtlCO,1 DArE "liVRE ,...,.....,.r .,.,,,..AUG 1983 .6-9 J I 1 1 ]I -J ,I )J J J 1 I J J .- GRADATION SIZE ANALYSIS u.S.Standard Sieve Openings In Inches U.S.Standard Sieve Humbers Hydrometer 12 9 6 3 2 lllZ 1 3/4 1/23/8 4 10 20 40 60 80 100140 200 270 100100....--......:.:..'"""-,.:......:LEGEND I......." i"l~r-r--r--.... WEIGHTED AVERAGE 1 90~b..I"-...90 ~r:::::~"I\.--"-UPPER!LOWER RANGE ""......~'"i\8080......""~1\ "t-............r-.....1\I'.7070 /D 1 ""..... r-.........I'.......-0",.,........."."60 .., '"~60 _.1'\-~~.,'";a.,. I ,,"'->, OJ i'50::II A];50 '\~1\...r'\.OJ<,0 C.. :b......1\-IJ .....<: 40;:40 1\..,~.'"ct-OJ..ecr-..""-OJ !\.\.30 OJ......:30 ".""I,".... 2020-"-.........."~ "1010 0 0.001 0 100 50 10 5 1 0.5 0.1 0.05 0.01 0.0051000500GrainSizeInMillimetersIBOULOERSIGRAVELISANDIFINES ICOBBLESICoarnIFineICoarseMedIumFineISiltShes.~1ay Sh,~ UNIT MATERIAL NO.OF SAMPLES FEET OF SAMPLE %MAT'L IN SECTION ALASKA POWER AUTHORITY G S/Lry CLAY.fCL/CL-ML)9 17 100 SUSITNA HYDROELECTRIC PROJECT 0 1 SA.NOYS/LT;IML)4 .,100 100 IWATANA DEVELOPMENTors/trY SANDI ISM/SM-SC)/8 23 RELICT CHANNEL<LACUSTRINE GRADA TION SUMMARY IJ.tIlLQ'lM1'3CO,1 DAfe l/liVRe MO".0••,""."AUG 198'3 .6-10