Loading...
HomeMy WebLinkAboutAPA1734I 1 1 ;1 il 1 r,:l I ;I ··I I 'J 1 J, I .I "' ,I I J ,. ~~~ I .. ,l L -I • ~ .. ;J.i' .. \ ' • SUSITNA HYDROELECTRIC PROJECT FEDERAL ENERGY REGULATORY COMMISSION PROJECT No. 7114 [}!J~[fdl£~t=J~ill3~®©@ SUSITNA JOINT VENTURE 1984 GEOTEC-iNICAL EXPLORATION PROGRAM W AT At" A DAMSITE MAIN REPORT FINAL REPORT JULY 1984 DOCUMENT NO. 1734 L ..._..__ALASKA POWER AUTHORITY ______ tit' ••.. ,.zamp;;.s ~~~*~~~~~~·~'-!Mf':-4t-,~~ l ::0 :m '1J -o ·:o .-f !""' ! fTI 'l( " -"' ..L -m -' ·-f ten , ;~_. __ -_ .. -. ' r ._, }. r ' I ~ .... ::.-: .. J I ~I I 'I I I I I I I ,. ) SUSITRA HYDROELECTRIC PROJECT 1984 GEOTECHNICAL EXPLORATION PRCXiRAM WATANA DAIISITE MAIN REPORT Report by Harza-Ebasco Susitna Joint Venture Prepared for Alaska Power Authority Fi!lal Report July 1934 Document No. 1734 Susitna File No. 5.6~1 ( a·~ I I I I I I I I. I I . I I I I, I I 14 ARY QUBST:IONS OR COMMBRTS CONCE'aR:ING TBl:S RBPOR~ SBOOLD BB D:IRBCDfD TO TaB ALASKA POWER AUTHOR:IT;t SUSl:DA 1-'ROJEC~ OPPI{".B I I I I I a I J I l I I J 1984 GEOTECHNICAL EXPLORATION PROGRAM WATANA DAMSITE TABLE OF CONTENTS SUMMARY AND CONCLUSIONS 1&0 INTRODUCTION 1.1 BACKGROUND 1.2 PROGRAM OBJECTIVES 1.3 PURPOSE AND SCOPE OF REPORT 1.4 ACKNOWLEDGEMENTS 2.0 EXPLORATION AND TESTING METHODS 2.1 GEOLOGIC MAPPING 2e2 OVERBURDEN-DRILLING AND SAMPLING 2.3 OVERBURDEN-BOREHOLE PERMEABILITY TESTING 2.4 BEDROCK-DRILLING AND CORING 2 •. 5 BOREHOLE ALIGNMENT SURVEYS 2. 6 GROUNDWATER SAJ:t1PLING 2.7 BEDROCK-HYDRAULIC PRESSURE TESTING 2.8 GEOPHYSICAL LOGGING 2.9 OBSERVATION DEVICES 2.10 LABORATORY TESTING 2.11 POINT LOAD TESTING 3.0 PE~~ITS AND ENVIRONMENTAL PROTECTION 4.0 INVESTIGATIONS IN FINS AREA 4.1 IRTRODUCTION 4.1.1 Previous Work 4 ~ 1. 2 Scope of Current Inves tiga ti.on 4.2 OVERBURDEN 4.2.1 General Description 4.2.2 Classification of Materials 4.2 .. 3 Material Properties 4.3 BEDROCK 50314/TOC 840725 4.3.1 Bedrock Topography 4.3.2 Lithology/Rock Quality 4.3.3 Structure 4.3.4 Alteration Zones 4~3.5 Weathering 4.3.6 Hydraulic Pressure Test Results 4.3.7 Geophysical Logging Results ~ - PAGE 1 1-1 1-1 1-2 1-3 1-3 2-1 2-1 2~2 2-2 2-2 2-3 2-4 2-4 2-5 2-6 2-6 2-7 3-1 4-1 4-1 4-1 4-1 4·-2 4-2 4-3 4-3 4-4 4-4 4-4 4-5 4-5 4-6 4-8 4-9 •• I l 11 J ' I I ' .1' TABLE OF CONTENTS (Cont'd) SECTION s.o 4.4 GROUNDWATER 4. 5 PERMAFROST 4.6 EVALUATIONS 4.6.1 Erosion Potential 4.6.2 Seepage Poteatia1 INVESTIGATIONS IN DOWNSTREAM 5.1 INTRODUCTION 5.1.1 Previous Work PORTAJ~3 AREA 5.1.2 Scope of Current Investigations 5.3 5.4- 5.5 OVERBURDEN 5.2.1 General Des:ription BEDROCK 5.3.1 5.3.2 5.3.3 5.3.4 5.3.5 5.3.6 5.3.7 . Bedrock Topography Lithology/Rock Quality Structure Alteration Zones Weathering Hydraulic Pressure Test Results Geophysical Logging Results GROUNDWATER PERMAFROST 6.0 INVESTIGATIONS IN AREA OF UNDERGROUND POWERHOUSE '.J .. 1 INTRODUCTION 6.1.1 Previous Work 6.1.2 Scope of Current Investigations 6.2 OVERBURDEN 50314/TOC 840725 6.2.1 General Description - PAGE 4-9 4-10 4-10 4-10 4-11 5-1 5-1 5-1 5-2 5-2 5-2 5-2 5-2 5-3 5-3 5-3 5-4 5-4 5-5 5-5 5-6 6-1 6-1 6-1 6-1 6-2 6-2 I I I I I l I - I I .. I SECTION TABLE OF CONTENTS ( Cont' d) 6. 3 13EDROCK 6.3.1 Bedrock Topography 6.3.2 Lithology/Rock Quality 6.3.3 Structure 6G3.4 Alteration Zones 6.3.5 Weathering 6.3.6 Hydraulic Pressure Test Results 6.3.7 Geophysical Logging Results 6 • 4 GROUNDWATER · 6.5 PERUAFROST 6.6 FOUfiDATION EVALUATION REFERENCES 50314/TOC 840725 PAGE 6-2 6-2 6-2 6-3 6-3 6-3 6-3 6-4 6-4 6-4 6-5 I I I I I I '<( -· J J I ~ fl -- I I I I I I NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 50314/TOC e4o725 EXHIBITS -VOLUME 1 TITLE PROJECT LOCATION MAP SITE PLAN AND VICINITY MAP 1984 GEOTECHNICAL PROGRAM -BOREHOLE LOCATION PLAN DAMSITE AREA -EXPLORATION PLAN iiNS OUTCROP AREA -GEOLOGIC MAP FINS AREA -EXPLORATION PLAN FINS AREA -BEDROCK CONTOUR MAP FINS AREA -GEOLOGIC PROFILE A-A FINS AREA -GEOLOGIC SECTION B-B FINS AREA -GRAPHIC LOGS~ BOREHOLES DH84-l, 4, 4A, 9, 10 DOWNSTREAM PORTALS AREA -GEOLOGIC MAP DOWNSTREAM PORTALS AREA -GEOLOGIC SECTIONS D-D, E-E, F-F DOWNSTREAM PORTALS AREA -GRAPHIC LOGS, BOREHOLES DH84-3, 5, 6, 7, 8 RIGHT ABUTMENT -GEOLOGIC MAP POWERHOUSE AREA -GEOLOGIC SECTION C-C POWERHOUSE A~~ -GRAPHIC LOG, BOREHOLE DH84-2 . l.V ,__ ____________ ----:·-·-·~---""~·-·--·--·-··-···~"-----··· I) TABLES 1.0 DRILL HOLE DATA SUMMARY APPENDICES APPENDIX A -BOREHOLE LOGS APPENDIX B -BOREHOLE PERMEABILITY TEST DATA APPENDIX C -HYDRAULIC PRESSURE TEST DATA APPENDIX D -GEOPHYSICAL LOGS APPENDIX E -LABORATORY TEST DATA/SOILS APPENDIX F -OBSERVATION DEVICES/GROUNDWATER APPENDIX G -POINT LOAD TEST DATA 50314/TOC 840725 v PAGE 2-8 VOL. 2 VOL .. 3 VOLs 3 VOL. 3 VOL. 3 VOL. 3 VOL. 3 'f· .. ··.· --;:-._·_·-::_ ....................... _._ ............... , ............... _ .......... _ ........ -·-···· ....... ------............ ... ' --~~-~-~-·~--.... -~ .. ~.-.,<--,---..--.----.. ,~"'·~-~------.. -~ ,, ·-''-'><'~--~~--........... _.,....__.,~ ' ' , ... l - ::D m , 0 ::0 -1 rr~, ><= :r: -[10 m --1 (JJ I I I I I 'I .. I I I I. I Fins Area 1984 GEOTECHNICAL EXPLORATION PROGIAH WATAlU. DAKSITE SUMMARY AND CONCLUSIONS An exploration program comprised of five deep angle holes, totalling 2676 lineal feet of core drilling and borehole testing, was <~onduc ted across the upstream. entrance face o.f the area known as the Fins. The program encountey;ed no evidence of major shearing or faulting which would lead to significant underground eros ion under filled . reservo~r seepage. or conditions. The rock mass behind the face of the Fins feature is dominantly hard, competent diorite, with locally developed zones of closely spaced. fractures, and alteration zones. Individual fracture and alteration zones have maximum widths of about 15 feet. A residual zone of highly weathered to decomposed diorite exists locally at the bedrock surface, beneath the cover of glacial overburden. The zone has a maxjmum thickness of about 70-80 feet. The decomposed diorite appears to be the same material as was encountered in borehole DR-20 which prompted concern by the FERC review team in August 1983. The decomposed rock shows a progressively less weathered profile with increasing depth. The in-situ weathered rock does not represent a zone of structural weakness deep within the projected trend of the Fins feature. Groundwater levels in bedrock at the Fins are consi~tently high, ranging in elevation from 2070 to 2142 feet. The high groundwater levels su?port the test data that indicate low transmissibility throughout the bedrock mass, from El. + 2160 to river level at El. 1450. With future full 50314/1 840725 T 1 I I I ' ' ' I I I I I I I I I I I I I I I pool reservoir level at 2185 ft., the underground hydraulic gradient for J-~ngth of 7000 feet to a possible outlet at Tsusena Creek seepage over a _ (El. ! 1670) is very low, being on the order of only seven percent. . l.S to be the result interpreted The origin of the Fins topography of headward erosion and ice wedging in normally jointed, fractured and altered rock, rather than being the result of deep eros1on of a major shear or fault-zone. The question ad to why fin-like topography developed at this . particuli:r point along the valley wall appears to be rel3ted to the local drainage basin lying immediately above the Fins (See Exhibit 6). The basin directs concentrated surface runoff and seepage to the Fins outcrop area where it can, erode the weaker or closely fractured rock and develop enlarged ravines and fin-like ribs by ice wedging and gravity toppling. Downstream Portals Area Moderately-to closely-fractured rock exists throughout most of the Downstream Portals Area, however, no major zones of shearing, faulting, or alteration were encountered. The Downstream Portals Area corresponds to the geol.ogit.:: area previously referred to as the nFingerbuster". The area is characterized by steep, rugged topography, partially wooded slopes, talus chutes, and limited outcrops along bedrock cliffs and benches. Geologic mapping has identified a dominant northwesterly structural trend and scattered outcrops demonstrate the presence of closely fractured rock and local shear I al teral:ion zones. Drilling in this area was undertaken to explore the extent of the fracturing, shearing and alteration which had previously been identified by surface mapping. The thickest alteration zone with weal< rock material is approximately 10 feet thick. The degree of rock fracturing varies widely in this area, and is influenced by structural control and near-surface, stress relief fracturing. 50314/1 840725 ;u A - ·- 2 ····~ I I I I I I I I I I I I l I I I I I Groundwater levels in the Downstream Portals Area generally vary from 40 to 80 feet below g~ound surface. Local permafrost conditions were encountered in part of the lower right abutment. Ice was found filling fractures in core from boreholes DH84-3 (in the inter·val from 8.0 to 27.3 feet) and DH84-8 (from approximately 18 to 54 feet). After completion of borehole DH84-6, ice was found blocking the standpipe piezometer at a depth of 50-56 feet. These were the only instances o.f ice being encountered in rock or soil in the 1984 program. Powerhouse (Design Refinement Location) A 765-ft deep borehole was drilled to explore geologic conditions in the . area of the proposed underground powerhouse. The rock mass in general is very hard, strong diorite and quartz diorite. Minor fracture zones and weak alteration zones were encountered, but primarily in the upper half of the borehole. Bedrock in the area of the proposed cavern was of excellent quality, characterized by high strength, high RQD's and low permeability. 50314il 840725 ,, ....• ,. ('' '. ' '?'?I .. ,.,.. -t ' 3 I I I I I I , , I I a· . I' 1'. I. ~~· J: J .. I. I~ I,. I" , 1.0 INTRODUCTION 1.1 Background In August of 1983, Engineers of the Federal Energy Regulatory Commission (FERC) conducted a site review of the Susitna Hydroelectric Project. The review included both the Watana and Devil Canyon Developments (See Exhibit 1) as both are included in the license applicaticm submitted to FERC. by the Alaska Power Authority in March, 1983. The 1984 Geotechnical Exploration Program was developed primarily to answer questions raised by the FERC review panel relative to the Watana development (Exhibit 2). The conceptual project plan for Watan~, as d3pictea in the license application, consists of an 885 foot high embankment dam impounding a reservoir approximately 40 miles long. Crest length of the dam would be roughly 4000 feet~ and the base of t:he dam would measure approximately 3900 feet in the upstream/ downs trea.m direction. Adjacent spi 1 bmy and power intake structures would be located immediately upstream of the dam alignment on the right abutment. A 1020 MW underground powerstation is proposed in the downstream right abutment (Exhibit 3). used to pass river flow during constructiono Two diversion tunnels would be 1 1.1 Principal Issue During the site visit, FERC Engineers expressed concern over the potential erodibility and seepage potential of the bedrock mass northwest of the Fins, an area of high rock cliffs containing se_veral nearly vertical zones of closely fractured and altered bedrock. The Fins lie immediately upstream of the proposed diversion tunnel core from Corps of Engineers decomposed, friable diorite intakes. The F_ERC Engineers also examined drill holes DR-18, DR-19, and DR-20. The from hole DR-20 prompted further concern relative to potential seepage and erodibility within the Fins feature. 50314/1 840725 1-1 r ·-·~-.. ~·····,--~·-------"' ---·-·""" ., e ~ . - 1 .. · * { . I I I I I I I 1·. I a: In a letter dated September 23, 1983, th2 FERC Engineers formally expressed concern to APA regarding the Fins area. The FERC letter also discussed potential impacts on licensing, and recommended fur~her geotechnical exploration in the Wi11ter/Spring of 1984. 1.1.2 Program Response In response to the FERC concerns, the Alaska Power Authority initiated correspondence with the FERC to discuss possible exploration programs at the Fins {correspondence dated October 12, 1983; November ~) 1983; November 9, 1983; and December 30, 1983). The fi.nal program re~ommendation, APA letter to FERC dated December 30, 1983 provided for subsurface investigation of the · Fins feature and additional work at the site of the Underground PI)Werhouse, and in the Downstream Portals Area (Fingerbuster Area).. The decision to extend the scope of the investigation beyond the immediate area of the Fins was made primarily to support the license applic.:ation by obtaining geologic information in the area of the powerhouse and the tailrace area of the proposed hydraulic structureso 1.2 Program C~jectives The principal objective of the 1984 Geotechnical Exploration Program V?a3 to further determine the character of th~ Fins feature and to evaL·ate the potential for seepage and erosion within the feature. These objectives were to be achieved through a program of surface . mapp1ng and subsurface investigations including core drilling, hydraulic pressure testing, borehole geophysical logging and groundwater observations and measurements. Additional objectives of the program were to obtain basic geologic information in two downstream areas of proposed major structures. The first of these was the Downstream Portals Area which includes the proposed 50314/1 840725 1-2 *?"+*''*"'*'*""' - I I I I I I I I I I I • locations for the spillway flip bucket and the outlet structures for the diversion and power tunnels. The second area was at the site of the proposed underground powerhouse (Design Refinement location) in the right abutment. These objectives were also t.o be achieved by a program of surface mapping and subsurface drilling and testing. 1.3 Purpose and Scope of Report The purpose of this report is to document and present the results of the 1984 Geotechnical Exploration Program, and to evaluate the data. .. ~ .·: ;- '· "' "· -... '\:. ·: . :. ~-" -. " The scope of the report also includes discussions of the inves tigatic,n · techniques, the env1.ronmental and permitting conditions of tl!e investigation, and background su~aries of previous investigations in the areas addressed. 1.4 Acknowledgements The Joint Venture wishes to acknowledge the pilrticipation and support of t:he Alaska Power Authority throughout both the planning and performance phaues of the field program. Technical advice and field review was provided by Harza-Ebasco Interlla\1 Review Board Members, Joe L. Ehasz, David E. Kleiner and Earl E. Komie. High standards of drilling and borehole testing were carried out by Interstate Exploration, Inc. of Anchorage, Alaska, under direction of the Joint Venture fi~ld staff. Field logistics support for the safe and economic conduct of the prqgr am uere provided by Frank Moolj ... and Associates, Air Logistics, and KNIK AD1: .. S~\rvey conttol and instrumentation moni taring was performed by R~1M Consultants. 50314/1 1-3 840725 ...... - I I I I I I I I I I I I I • I 2. 0 EXFLORATIOH AND TESTING The scope of the various exploration and testing aspect~ of the 1984 Geotechnical Program is presented in the following section, 2.1 throt,.:::,':1 2.11. 2.1 Geologic Mapping ·A program of geologic mapping and review of previous work was conducted in August and September, 1983, for the Fins outcrop area and the Do~stream P":trtals area (Fingerbuster Area of previous reports). The limited outcrop on the upper right abutment, in the general area of the proposed spillway approach and power intake, was also mapped at this time. The maps (Exhibits 5 l 11 and 14) are p"t"esented at scales of one inch = 50 feet for the ~.,ins and the Downstream Portals Area; and one inch = 100 feet for the Upper Right Abutment. The scale change from previous work (one inch = 480 feet) was made to be consistent with future engineering layout work.. field mapping was . us1ng a close network of performed Tape and compass established survey. points for control. Map preparation involved checking and integrating current work and that from previous mapping programs (Corps of Engineers, 1978; and Acres Ar'.erican, Inc., 1980-1983). The philosophy of the current map presentations i8 to restrict projection or extension of features beyond their actual limits in the field. This was done in order to more clearly identify known geologic control on the maps. Office work also included preparation of joint set contour summaries for each of the mapped areas. The geologic mapping has been used in evaluating project refinements to the 1 icense applica.t ion, and in. establishing the orientation and location of boreholes for the current Geotechnical Explor.ation Program • 50314/2 840725 ....... 2-1 - I I~ ' I 1\ ; I ' . ftl I I I I I I I, ~ 2.2 Ovet'burden Drilling and Sampli~ All drilling in overburden was accomplished with helicopter-transportable, Longyear-38 drilling r~gs equipped with HQ size, triple tube, wireline coring equipment. Samples were recovered using a 5-ft barrel with 2-split inner liner. Soils from glacial deposits, including alluvium, till and lacustrine materials, were successfully recovered from several boreholes in the Fins area when a polyacrylamide, non-particulate drilling additive was used to increase viscosity of the circulation fluid. Use of the polymer system allowed nearly 100% recovery in the overburden deposits, whereas little to no recovery was possible when using only water as the drilling fluid • Samples were wrapped . ~n plastic to being to maintain moisture . pr~or photographed, and representative samples were selected for laboratory classification testing (Appendix E). 2.3 Overburden-Borehole P~'rmeability Testing Several constant head tests and one falling head test were conducted ~n overburden. Data are presented in Appendix B. The majority of the overburden drilling in the Fins area was performed, as discussed above, with a polymer drilling additive which allowed virtually 100 percent core recovery in the soil section. Review of the soil samples revealed no materials of potentially high permeability and therefore permeability testing was minimized. 2.4 Bedrock Drilling and Corin& Coring equipment at all rigs was HQ-size, triple tubr wireline core barrels, five feet long, with split 50314/a 840725 . , . ~nner J.~ners. NQ wireline equipment was also 2-2 T - 11 ! r 1., I I I, -. -~ availal:>le but was used in only one borehole to advance approximately 60 feet below the HQ size hole (DH84-4, 318 feet to 378 feet). All holes were drilled at angles of 30°-35° from the vertical. In most instances it was possible to drill sucessfully with clear water as the drilling medium. In the deeply weathered :?ection of the Fins area, however, it was necessary to use a drilling additive (the non-particulate, polymer discussed in 2.2) to increase core recovery and remove cuttings from the boreholes. Very high core recovery was possible even in zones of friable material when the polymer was used. The polymer also permitted more complete flushing of drill cuttings which otherwise tended to settle and bind the drill string and casing in the borehole. A total of 4370 lineal feet of bedrock coring was completed during the 1984 program. A summary table of drilling statistics (Table 1.0) is presented at the end of Section 2.0, page 2-8. All core was logged and checked in the field (See logs in Appendix A). Record photographs of all core were taken and are on file in the Harza- Ebasco office in Anchorage (one record set also submitted with (tt'iginal report to FERC). The core is now housed in storage facilities in Anchorage along with all other core and soil samples from the Watana site. 2.5 Bnrehole Alignment Surveys Two deep boreholes in the Fins area j DH84-l, DH84-4A, and the Underground Powerhouse Hole$ DH84-2, were surveyed using a Sperry-Sun, single-shot, borehole camera, to determine hole alignment. The unit, which consists of a flo;;a_ting compass, timer, camera and film, and 15 feet of non-magnetic rods, was lowered down the hole through the wir~li.ne rods on the wire line cable. The 15-foot length of non-magnetic rods carried the instrument through the wireline bit, beyond the magnetic influence of the drill string. The instrument was retrieved after each reading to process the film disk and reload. 50314/2 840725 2-3 r J I' I I I I -J Surveys were generally taken at 100 to 200 foot intervals when the drill rods were pulled, either during a bit change or upon completion of the hole. Inclinations and bearings . 1n the three boreholes surveyed, remained consistent to within one to two degrees throughout the length of the borehole. 2.6 Groundwater Sampling A program of groundwater sampling and analysis was initiated in order to characterize tne geochemistry of groundwater in the Fins area. Samples for analysis were also obtained from the lake water that was used ~s drillwater supply. Following initial sampling at a borehole, the borehole was bailed using a modified air lift, which employed compressed nitrogen introduced at the bot tom of each hole through 3/4 inch -diameter steel rods. Samples were again taken after the water level within the borehole had recovered. The pH of water samples was read directly in the field. The samples were then sealed and shipped to Anchorage for laboratory analysis. The analyses reported the following parameters: conductivity; total dissolved solids; and concentrations of Na, Mg, K, C03, HC03, HS04, CI, N03, and B. The data are maintained on file for incorporation with future monitoring and sampling work. 2.7 Bedrock-Hydraulic Pressure Testing Hydraulic pressur@ permeabilities of 50314/2 840725 tests were conducted in boreholes to estimate relative the rock mass. All tests were conducted with an 2-4 I I I I . I I I I I I I I, open-bottomed, wireline packer system lowered through the drill rods to test the interval of hole below the drill bit. In general, boreholes were tested in 50-foot intervals as the drilling progressed, however . 1.n some cases, longer intervals of boreholes were tested by moving progressively uphole in 50 foot increments. In these cases the water take values of lower intervals were subtracted from higher interval tests to estimate the water takes of higher zones (further discussion is presented in Appendix C). Boreholes in which drilling additives were used to maintain hole conditions were thoroughly treated and flushed prior to conducting final water tests. All pressure tests were conducted by measuring water losses at three increasing pressures~ and then reversing the sequence of pressures to return to the initial test pressure. The test data were converted to Lugeon valvas for co· 1arison between test intervals. The summary table of Lugeon values· is presented 1.n Appendix C, and representative Lugeon values are shown on Exhibits 10, 13, and 16 • 2.8 Geophysical Logging Geophysical logging was conducted to aid in the interpretation of subsurface data, especially in zones of poor core recovery; and to provide a standard to evaluate use of such techniques in future programs. The geophysical program consisted of density (gamma gamma), porosity (neutron), and a natural gamma logging. The density tool was selected to develop criteria for recognizing low density zones such as fractured, sheared, altered or deeply weathered . rock. The neutron or porosity tool was used to help identify water bearing zones and static water levels. The natural gamma tool was use~ to indicate correlations between boreholes and to assure that boreholes were free of obs true tions (it was necessary to 50314/2 840725 2-5 r-_ I I I J I I I I I I I I J f assure the open conditions and safety of each borehole prLor to using either the neutron or density tools, since both employ nuclear sources closely regulated by the NRC). Geophysical surveys were run in all boreholes of the 1984 current program, and they are presented in Appendix D along with equipment descriptions, notes on operational procedures, and general notes on interpretation of the logs. 2.9 Observation Devices Each of the boreholes drilled in the current program is equipped so that water level(s) within the borehole can be monitored. The specific installations vary from single, open-standpipe piezometers using 3/4 inch to 2-inch ID slotted PVC, to inst~llations covering two intervals within one borehole. Remote sensing pneumatic pressure cells were also added to some installations to ensure continuity of readings during the winter months when near surface water in the piezometer.s would be subject tc freezing. Summary sketches of piezometer installations and recovery curv~s for the bailed piezometers are presented in Appendix F. 2.10 Laboratory testing/Soils Representative samples from the overburden encountered in the Fins, and soil-like materials from the buried weathered zone were tested for classification at the on-site soils laboratory. The materials were classified according to the Unified Soils Classification System. Atterberg limits were determined for the fine grained materials, while grainsize analyses were conducted on the coarser fractions. was tested. Results are presented in Appendix E. 50314/2 840725 2-6 A total of 15 samples I I I fl ~' ' i "-'~ 2.11 Point Load Testing Diametral point load tests were performed on representative bedrock samples to establish a range of values for st-..:.cific rock types. The tests were performed at the on-site laboratory as the core was being reviewed during final logging. Test data and notes are presented in Appendix Go 50314/2 840725 2-7 .. . , -v , •...• .:)-'1 ' • ..--_...,.,... r t •• • • ·-· ~-li'filfQII!iM$ I . l ' ::~ ·' j l ! f ! ! j ! i ·• I l . f I l I ' 1 ltt~of!i I ) I, ! l ! l_ ~ aw.w 00 \.11 ~0 ow '-J ...... N~ IJ1 ......_ 1\.) N I 00 ~~ ·~~ .,..,. __ l1iii ]iii ~ 12§1 ~ ;;.'4 Cil ;;:a b1l .ta &:JI f?ll 1:11 bll =-~ l1liiiiii ~ \' . Table 1.0 1984 Exyloration Prograa Data SWIDilary Inclination Borehole Ground Surface Overburden Bedrock Total Number Azimuth From Vertical Elevation (ft) Thickness (ft)l Elevation { ft) Depth. ( ft) - DH84-1 244° 34° 2143.1 18.5 2124.6 848.5 DH84-2 019° 30° 2024.2 14.7 2011.5 765.0 DH84-3 025° 30° 1503.3 8.5 1495.9 132.2 DH84-4 050° 35° 2161.4 116.9 2065.6 378.0 DH84-4A 040° 35° 2167 .. 8 72.4 2108.5 698.5 DH84-5 010° 30° 1725.6 15.1 1712.5 265.0 DH84-6 025° 30° 1521.4 9.0 1513.6 167.8 : DH84-7 025° 30Q 1625.3 4.2 1621.7 263.5 DH84-8 012° 30° 1677.1 8.5 1669.7 100.0 DH84-9 225 ° 35° 2161.5 148.2 2040.1 497.5 DH84-10 230° 35° 2161.5 6le6 2111.0 254.0 1 Overburden thickness as measured along the hole axis. I I - I I I 3.0 PERMITS AND EHVIRONMEH~ PROtECTION The 1984 Geotechnical Exploration Program was conducted with land use authorizations and permits obtained before and during the program. Permit stipulations and control of exploration activities resulted in the program being executed with minimal damage to the environment. A nationwide permit (Section 404) from the U.S. Army Corps of Engineers authorized fi~ld explorations on Federal lands. The Alaska Power Authority coordinated land use with CIRI Native Corporations. Other permits obtained include a temporary water use permit (No. SC/MS 84-1) from the Alaska Department of National Resources (ADNR). Archaeological clearance of all boreholes was obtained from the University of Alaska Museum/ADNR. Rail Transport was coordinated with the Alaska Railroad. 50314/3 840725 r-.. 3-1 . ~ .... 4.0 INVESTIGATIONS IN FINS AREA 4.1 Introduction 4.1.1 Previous Work Previous work relating to the Fins feature has invCilved geological mapping 0 ,f the outcrop area along the inner gorge of the Sus i tna River Valley, and subsurface projection to the northwest from the outcrop toward Tsusena Cr~~ek. The projections were based on seismic interpretations, and an outc.~rop of altered and sheared diorite located on the northwest bank of Tsusl~na Creek (Acres American,· 1982 PP• 5-23 to 5-27). In 1978, the U.S. Army Corps of Engineers drilled five boreholes along the strike projection of the feature (DR-16, -17, -18, -19, and -20) but maximum penetration of bedrock was limited to only 42 feet. The 1983 \¥inter exploration program also involved borings in this area (see Exhibits 6 and 7), but the investigation was aimed primarily at soils exploration and penetration into bedrock was quite limited. The basic information available from previous mapping is that the outcrop area of the Fins is comprised predominantly of sound, jointed bedrock, but the rock mass also contains steeply inclined, northwesterly trending zones of closely fractured rock, 5-!0 foot wide zones of weak, friab~e altered rock and zones of plastic, sandy clay which measure one inch to approximately one foot in thickness. The zones are difficult to trace in outcrop due to the steepness of the terrain, talus cov.er, and thick overburden deposits above approximate elevation 2000 feet. 4.1.2 Scope of Current Investigation The current program to investigate the erodibility and seepage potential of the rock mass in the Fins area involved 2,676 linear feet of coring in a series of five deep, inclined boreholes. 'The boreholes were spaced acres s the projected strike of the Fins to achieve coverage of approximately 900 50314/4 840725 T f 4-1 fJ ~· u~ fl feet perpendicular to strike, and 400 feet parallel to the strike trend (Exhibits 6 and 9). Hole depths ranged from 254 feet to 848.5 feet. The total vertical span covered approximately 700 feet from an average elevation of about 2150 on the upland surface to elevation 1450 approximately at river level. Each of the holes was drilled, tested and completed with observation devices under direct supervision of a rig geologist/inspector. Core was logged directly at the hole as it was recovered (logs presented in Appendix A); and all core and logs were reviewed aga~n at the site storage facility for completeness and uniformity. Boreholes DH84-1 and DH84-4, and -4A follow the original plan of spann~ng the projection of the Fins feature. Borehole DH84-9 was added to obtain geologic information along strike to the northwest; and DH84-10 was added to extend geologic coverage beyond the projected featur.e to the southwest. 4.2 Overburden 4,2.1 General Description Overburden thickness in the area drilled ranged from about 15 feet at DH84-l to a maximum of about 95 feet at DH84-4. The materials generally consist of moderately weathered to unweathered dense glacial deposits rang~ng from slightly clayey, silty sand to pebbly, bouldery silty sand. The compact nature of the glacial deposits was confirmed by the geophysical logging which showed the apparec ·-density of the overburden section to be locally comparable to competent bedrock. Drilling in the overburden encountered no zones of high permeability. Testing is primarily limited to several constant head tests performed in DH84-4, and these indicate permeability values on the order of lo-4 em/ sec. Data are presented in Appendix Bo 50314/4 840725 4-2 ,. UIJ I Inspection of continuous core across the contact between overburden and the underlying zone of decomposed diorite indicates that the contact is also impermeable. 4.2.2 Classification of Materials Index property tests were performed on selected samples of overburden and the decomposed diorite from the Fins area. All samples were prepared and tested using ASTM methods. Materials were classified using the Unified Soil Classification System. Soil descriptions are based on field and laboratory visual examination and laboratory test results. The test results for grain size distribution, Atterberg Limits and moisture content tests are presented in Append~x E, and are discussed below in section 4.2.3. 4.2.3 Material Properties Ten soil samples from the overburden 1.n boreholes DH84-4, -4A, -9 and -10 were selected for gra1.n size distribution and plasticity testing. The samples we .... 1 found to consist of well graded, medium to fine grained sand, silty sand, and clayey sand (SW, SW-SM, SC); and silt and clay (ML, CL). The data (see Figures E-1, E-3 and Table E-1 in Appendix E) indicate that the stratigraphically higher soil samples generally consist of clay and very clayey sand, with an average of 51 percent of the matarial passing through the 4F200 sieve. The materials have low plasticity with an average Liquid Limit of 19, and an average Plastic Index of 6. Atterberg Limit test results are shown in Figure E-3. The data fall just above the A Line in the clay and silt-clay region of the chart. The stratigraphically lower soil samples generally consist of clean to silty, well graded sands. The average fines content in these samples was determined to be 5 percent paosing through the #200 sieve. In addition to the classification of overburden soils, five samples of decomposed diorite were also tested. The samples were taken from boreholes 50314/4 840725 4-3 r-_, ... , oa . I 1 ~~ I ~: I I I DH84-4A, -9, and -10. Ins pee tion of Figure E-2 and Table E-1 (Appendix E) indicates that the deeply weathered diorite, when mechanically broken down to a soil, results in medium to fine grained, poorly to well graded sands and silty sands (SW, ~P-SM, SW-SM)c The average fines content passing the #200 sieve was 6 percent. 4.3 Bedrock 4.3.1 Bedrock Topography Buried bedrock topography . 1n the Fins indicates a northwesterly area trending topographic low extending from elevation .: 2100 feet at the current drill area to elevation + 1700 feet at Tsusena Creek (Exhibit 7). Top of bedrock in the Fins boreholes lies be tween elevations 2066 and 2125. The close spa..cing of holes in the area of DH84-4, -4A and -10 indicates that locally the bedrock surface (top of decomposed diorite) varies in relief to a greater extent than the sur~ace topography. Relief on the bedrock surface in this immediate area is shown to be as much as 45 feet vertically in a horizontal distance of only 60 feet (Exhibit 9). The relatively steep relief . lS the result believed of differentia~ eros1on . pr1or to be to deposition of the glacial overburden. 4.3.2 Lithology and Rock Quality The bedrock encountered in the Fins area consists primt.trily of hard, strong diorite and quartz diorite. Intervals of andesite porphyry and minor felsic dikes were also encountered. With the exception of local, highly altered zones and the decomposed diroite weathering zone to be discussed below (sections 4.3.4 and 4.3.5), rock quality across the Fins area appears to be quite good: RQD values vary considerably (Exhibit 10), but with regard to seepage potential erodibility, no uncommon or extensive rock defects were encountered. 50314/4 840725 4-4 If tl r1 fl 4.3.3 Structure Drill core from the current program presents a virtually complete picture of the structural features of the Fins area. The high percentage of recovered core. adds continuity and de tai 1 to the s true tural features observed from mapp~ng, and the new data generally confirm the validity o:r the early surface observations. ·Zones of closely fractured rock as much as 15-20 feet wide are present (see Exhibit 9), in the Fins area, and all boreholes encountered a~eas of fractured rock. There . 15 however no evidence indicating continuity of fracture zones, either by correlation between boreholes or by high takes during the pressure tests. Detailed examination of fracture surfaces in the core reveals occasional instances of slickensides, and clay infilling which may be related to loc.~al shearing. Healed breccia and healed microfractures are also common in the overall rock mass. The most significant observation regarding structural features 1n the core is that no major, through-going structural elements persist through the area of the Fins indications feature. No major faults, of structural weakness were shears, breccia zones or other encountered that might permit excessive seepage or internal erosion of the rock mass comprising the Fins area. Another indication of the lack of maJor structural features or extensive poor rock conditions was the ability to drill inclined boreholes to depths of 700 to 850 feet with deviations of bearing and inclination amounting to only 1-2 degrees. 4.3.4 Alteration Zones Hydrothe!rmal alteration in the Fins, as elsewhere on the site, has affected the bedrock to widely varying degrees. In most cases a yellow to red 50314/4 4-5 840725 l .... ~--- • llr fl tl fl fl alteration of feldspars is apparent with little to no effect on the structural integrity of the rock. At the opposite extreme, and to a much tesser extent, the bedrock may be locally altered to a bleached, grey/white, d rUliiiJ).y or clayey, low density, friable material with very low strength o This rock can be broken easily with finger pressure. Kaolin and chlorite are the dominant secondary minerals. The alteration processe!S appear to have gained access to the rock mass through discrete fractures or fracture systems. In some instances an alteration zone 2 to 3 inches wide may be developed on either side of a distinct fracture, but in most cases there is no readily apparent control s tructur'e. The local zones of deeply altered and weake~ed rock occur with mu.ch the same distribution and lack of continuity cts the zones of closely fractured rock. Maximum thickness, assuming verticality, of any single severely altered zone is on the order of 5-10 feet. 4.3.5 Weathering Two distinct styles o.f weathering have developed in the Fins area. At borehole HD84-l on shown primarily by the northeast side ~f the area, bedrock weathering it, iron oxide stains on · joints and fractures. On the southwest side of .the Fins area, however, a thick weathered zone of decomposed diorite has developed as a "cap" on the bedrock surface. The decomposed diorite was first encountered in hole DH84-4 but· core recovery was very low. Subsequent drilling with a polymer additive system increased ~ore recovery to essentially 100% and the nature and origin of the material became readily apparent. As shown on Exhibit 9, the h!.ghly weathered zone is developed to a maximum. depth of approximately 70 to 80 feet. The rock within the weathered zone is decomposed diorite, with crystal fabric still quite evident, but the rock is friable and breaks down readily to coarse, sand-size particles. The upper 50314/4 840725 l I 4-6 - rm. portion of the zone is iron-stained. gradually over several tens of feet. The transition to sound rock occurs No pressure tests have been obtained in the highly weathered zone due to the inability to seat packers, but there have been n.o indications of high the zone, permeability . 1n either by loss of dri llwater or by visual inspection of the recovered core from DH84-4A, -9 or -10. The presence of a weathered zone of decomposed bedrock had not been recognized previously at the site, presumably because preservation of the zone is dependent on a mantle of overburden and it has therefore not been observed in outcrop. Material recovered in Corps of Engineers borehole DR- 20, however, is also highly weathered-to decomposed diorite from beneath a cover of overburden deposits, and it is now evident that the core from borehole DR-20 represents partial penetration of the same highly weathered bedrock zone defined by the current drilling programo The areal extent of the buried, decomposed diorite zone is not known with certainty beyond the occurences in boreholes DH84-4, -4A, -9 and -10; and DR-20, 1700 feet to the northwest. Preliminary review of refraction seismic data, however, does indicate a small area in the southeastern part of the Fins feature which has lower seismic velocity response than the surr?unding areas (Exhibit 7). The velocity contrast is from 11,000-12,000 ft/sec to 13,000-18,000 ft/sec. A direct correlation of the lower seismic velocity area with the decomposed diorite zone is not fully tested, however the higher velocity response in the surrounding areas, as well as previous borehole information in the surrounding areas, indicates that the "cap" of decomposed diorite is of limited extent .. 50314/4 840725 4-7 0 '-:; I ) ' I ' l. ' m ' [ II r· ll .. ':' . . 4.3.6 Hydraulic Pressure Test Results The results of hydraulic pressure testing ~n the Fins boreholes are presented in tabular form in Appendix C, and graphically on Exhibit 10. The most complete testing was performed in DH84-l, the initial hole in the Fins area, a hole drilled with water as the circulation fluid. The test data indicate very low permeability, with Lugeon values ranging from 0.0 to a maximum of 3.5. Testing in DH84-4, a second borehole drilled with water, also indicated low water takes. Lugeons values of 0. 6 to 1. 6 were calculated for the lower part of the borehole but complete testing was not possible due to the lack of packer seats in the decomposed to highly weathered zone at the top of the borehole. Indeed, removal of drill cuttings from the borehole became an increasingly difficult problem as the cuttings continually built up around the rods and caused seizure of the drill string. Repeated cement plugs were not able to control the problem. Even after casing had been advanced through the decomposed diorite zone, cuttings bound the rods at a depth of 378 feet and a decision was made to abandon the hole and redrill using a polymer additive system. The polymer additive greatly improved recovery in the remaining boreholes and helped eliminate the binding of rods. As a consequence of using the additive, the remaining boreholes were not pressure tested until final depth was reached, at which point the polymer was flushed out; the borehole was treated with a chlorox solution; and then reflushed with fresh water. Short duration hydraulic tests were then conducted over large intervals of the borehole as there was still considerable risk of locking the rods during the testing operatia~ when circulation in the water-filled borings had to be stopped. No tests were conducted in DH84-10 because of indications of binding even with the use of the polymer drilling additive. 50314/4 840725 4-8 . ·r· ' .. -------~-----.... ··-·---~ .. ·-----.......... """··-···.r·------·------- -rJ ' ' ' ': '1 .. i.• t ; fl l~~ il Tests from bor'eholes in which the polymer had been removed also showed low permeability~ less. The range of results for all such tests was 1.0 Lugeon or 4.3.7 Geophysical Logging Results Results of borehole geophysical surveying in the Fins area (see Appendix D)indicate that hard, strong diorite is present at approximately 100 feet (vertically below ground surface) in DH84-4; 110 feet in DH84-10; between 98 and 115 feet in DH 84-1; 115 feet in DH 84-4A; and 220 feet in DH 84-9. In each borehole below these depths, the diorite is less fractured and jointed, is mostly fresh and unweathered, and becomes more dense and more competent with increasing depth. The overburden is generally characterized by a lower neutron count (higher water content) than the underlying rock. Glacial till ~s generally characte.rized by a lower gamma-gamma count (higher density) than the overlying clayey silt and sand and the underlying deeply weathered diorite. For example, ·in DH 84-4A and DH 84-10 where geologic samples and core indicate stiff, dense basal till overlying weathered diorite, the logs show a slight increase in porosity and a large decrease in density with depth. The large density shift at 18 feet on DH 84-4A marking the top of brown, clayey sand correlates with the + 42 foot point on DH 84-4. 'Dense ti 11 is indicated by the density log in the 40-80 foot interval of DH 84-4. 4.4 Groundwater Bedrock groundwater levels determined in the current inves tigat:ion of the Fins area are uniformly high, ranging from El. 2070 to El. 2142 (recovery curves and stabilized waterlevels are presented in Appendix F). By plotting piezometer data vertically above the instrument position in the inclined borehol~s (see Exhibits 9 and 10), groundwater across the Fins is indicated at a general depth of 10-20 feet below ground surface. 50314/4 840725 l I. l 4-9 - ~·~ liJ ~ !lll t· 1 I\ II ~::'! The high grouu.dwater levels associated with all of the current boreholes, as 11 b · t·n the area (see also Exhibit 8) are a primary we as prevtous ortngs . indication of the overall low permeability of the bedrock mass in the Fins area. Further, it should be noted that the current groundwater levels are only 40 to 115 feet lower than normal pool elevation of 2185 feet, so that full reservoir conditions will mean only slight changes in the. elevation head difference of the groundwater between the Fins area and Tsusena Creek, where seepage is now essentially non-existente 4.5 Permafrost No ice was present in any of the core recovered from the Fins area drilling and no other indications of permafrost were encountered during subsequent testing and moni taring. This condition is consistent with the results of other borings and thermister data in the immediate area. 4.6 Evaluations The data obtained in the current investigation indicate that the potential to develop significant seepage losses or internal erosion within the rock mass extending from the Fins outcrop to Tsusena Creek is extremely low. 4.6.1 Erosion Potential The occurence of soil-like material in the decomposed diorite zone and in severely altered sections tn the subsurface of the Fins area has been established by the current investigation. The question of whether the material is erodible, however, is primarily dependent upon the physical nature of the materials (fabric and compactness), the degree of confinement, and/or access to water having sufficient velocity to move particles. Visual inspection ot core and soil classification results both indicate that the material is not subject to piping or internal erosion. 50314./4 840725 1 l 4-10 ·(jl • 'I ~ ~ .·.~ (I ~ fl; I j. > ··; IR!f ~ ; ll ~; I JJ 11 I ' ' ""_ ... ····t.,:-- ,.' .. ~i-> On the entrance face of the Fins outcrop it is clear that surface weathering f · 1.. erode weaker rock materials and undermine and erosion can pre erent1.a 1y adjacent areas of strong rock. In the subsurface however, the weak materials are discontinuous in extent and are confined either by massive rock or by an overlying layer of very dense glacial till~ Further, there has been no indication of c1pen fractures or breccia zones which could · · · -1 f t r The conf1'nement ot-weak rock materials ma1.nta1.n an eros1.ve r ow o wa e • in the subsurface, the low gradient (approximately seven percent), and the lnw bedrock permeability combine to indicate an extremely low probability of developing internal erosion conditions in the Fins feature. 4.6.2 Seepage Potential The potential for development of excess1.ve seepage through the rock mass of the Fins, from the outcrop in the reservoir area to Tsusena Creek, is also extremely low. For such conditions to develop, the rock mass would have to be characterized by open, permeable conditions which might accompany major regional faults, or shear and b1:eccia zones. The subsurface drilling and testing data demonstrate that the rock mass is not cut by such major structural zones. The high groundwater levels in the Fins area also indicate low permeability th~oughout the rock mass. If the :t;'ock mass contained areas of high permeability, the regional water table would be drained to a much lower level than is currently maintained. Over 600 feet of head differential now exists between the current boreholes (DH84-l, -4, -4A, -9 and -10) and the Susitna River, a distance of 1200 feet; and this potential gradient of 50 percent has produced no indications of unusual seepage at the Fins, In conclusion, the addition of about 100 feet of reservoir head to the high static water levels in the Fins would result in an overall gradient of seven percent acting over a 7000-foot flowpath towards Tsusena Creek. This low gradient and the low bedrock permeability would result in insignificant seepage to Tsusena Creek. 50314/4 840725 1 ~ 4-11 • PI Ill ·I: j ' ·-·' ~l·l· I i ll IJ 5.0 INVESTIGATIONS IN DOWNSTREAM PORTALS AREA 5.0 Introduction 5.1.1 Previous Work Previous surface work in the Downstream Portals Area, also known as the "Fingerbuster" (Corps of Engineers, 1978), has included general reconnaissance, tape and compass geologic mapping (COE, 1978; Acres 1980-82, and Harza/Ebasco, 1983) and seismic refraction profiling ( 1978, 1980 and 1982). One deep (401 ft) exploratory borehole (BH-2, Acres 1980) was also drilled in the westernmost portion of the area to investigate the Fingerbuster area (Exhibit 4). Geologic mapping has stru~tural orientation indicated dominant northwesterly and for jointing and fracturing .. Slosely northerly fractured, sheared, and weak, hydrothermally altered rocks crop out in limit~d areas, but their extent is largely concealed by vegetation, talus, and the limited access on steep terrain. As in the Fins area, most of the rock outcrop ~s hard massive diorite with open jointing very evident on the steep slopes of the inner gorge. Seismic refraction work has indicated a near surface zone of low velocity rock ( 7000 ft/ sec) extending to depths of roughly 50 to 100 feet below ground surface in the area of the spillway bucket. The seismic lines where this occurs are shown on Exhibit 4 (see SL82-7, SL82-8, and the westernmost 200 feet of 8182-6). Additional low velocity zones, 7500 ft/ sec to 9000 ft/sec, were also nt;>ted on line 8182-5 further upslope along the spillway alignment (see Acres, 1982 Supplement to the 1980-81 Geotechnical Report, Volume 2, Figs 6, 7 and 8 for profiles of all lines referenced above). 50314/5 840725 5-1 l'' --,-_ '' I ' t ' I I [ ' t I ' L 1], ~~~ I; J)l 5.1 .. 2 Scope of Current Investigations The current program to obtain basic geologic information in the Downstream Portals Area consisted of the drilling and evaluation of five inclined boreholes, ranging in depth from 100 to 265 feet. The boreholes were oriented to cross the general northwest strike of the geologic structural trends, with locations in the area of the spillway cut, spillway bucket, and the area of the diversion and tailrace tunnel portals (Exhibit 3). 5.2 Overburden 5.2.1 General Description Overburden in tne Downstream Portals area was found to consist of a shallow pervious cover of talus, slope debris and remnants of river alluvium. Talus· blocks generally measure two or three feet in maximum dimension, and overall thickness of the overburden . l.n the boreholes was found to vary from approximately 5 to 15 feet, 5.3 Bedrock 5.3.1 Bedrock Topography The generally steep valley slopes in the Downstream Portals Area contain little to no overburden as evidenced by mapping and the current drilling program. As a result, surface topography of the steeper slopes 1.s a reliable indicator of bedrock topography. The Oa:;;ly general exception is the area southeast of boreholes DH84-3 and -6. Here, the terrace-like bench below Elevation 1500 suggests deeper overburden cover and this is supported by the approximately 50-foot (vertical) section of alluvial material encountered in borehole HD83-47 which was inclined beneath the terraced area from the north bank of the. river. 50314/5 840725 l. { rj Jl S-2 -- il I i I i L •• 5.3.2 Lithology/Rock Quality Bedrock in the Downstream Portals area ranges 1n composition from diorite to d . · Much of the rock mass is unaltered, but the effects of quart~ 10r1 te. hydrothermal alteration are still evident to varying degrees. As elsewhe.re on the site, the quality of the rock mass is largely a function of the degree and extent of alteration and fracturing. In general terms, rock quality in this area can best be characterized as highly variable. The extent or degree of alteration is not unusual (see section 5.3.4), however the intensity of fracturing, especially in the boreholes drilled on the steeper rock slopes (DH 84-5 and -7), is such that low RQD values can be found throughout much of any· given borehole. In contrast, there are areas of very high quality rock as in boreho:e DH84-3 which encountered very strong, hard diorite throughout its length (see Exhibit 13). The rock quality 1n the Downstream Portals Area 1s controlled by a combination of structural influence as well as near surface stress relief. 5.3.3 Structure All five boreholes drilled in the Downstream Portals Area were oriented to intersect the major west-northwest trending joint systems determined from surface mapping (Exhibit 11). Although the boreholes did encounter much variability in fracturing, no major structural features were identified. The area is characterized by a widespread condition of variable jointing, local sheared and altered areas, and local occurren~es of healed breccia. 5.3.4 Alteration Zones Hydrothermal alteration of bedrock in the Downstream Portals Area involves essentially the same range of variations as seen in the Fins area. Slight 50314/5 840725 5-3 1;.· ' ' l.!.l! alteration is suggested by minor color changes in the feldspar groundmass with no apparent loss in rock strength. Severely altered materia 1 however has a bleached 3ppearance from the development of kaolin and chlorite, and frequently has a d!UDWJy, friable texture, and very law strengthc Severely altered rock occurs in zones 0.1 to 0.2 feet wide adjacent to shear or fracture planes, or in nearly vertical zones up to approximately 8-10 feet in thickness. There appear to be no predictable patterns to its ·distribution. 5.3.5 Weathering Surface weathering in the Downstream Portals Area is limited primarily to iron-oxide staining. There is no in-situ zone of decomposition, as noted 1n portions of the Fins area. The depth of staining is quite variable owing to the control of fracturing and has little effect on the quality of rock from a structural standpoint. 5.3.6 Hydraulic Pressure Test Results The results of hydraulic pressure testing in the Downstream Portals Area are presented in tabular form in Appendix C and graphically on Exhibit 13. Hydraulic pressure tests were conducted in this area to explore for open fractures. As seen on Exhibit 13 and 1n Appendix C, water takes were locally quite high, however such water takes are not unusual considering the steep relief through the area and attendent stress relief fracturing. 50314/5 840725 5-4 . ····--~-...... ".'·~-~, 'I ---·· ~ ~ '• 5.3.7 Geophysic~l Logging Results -Downstream Portals Area Borehole geophysical logging 1n the downstream portal area was completed in all five shallow boreholes: DH 84-3, -5, -6, -7, and -8. All of the borehole logs show increasing density with depth below 65 feet (vertical) becoming very dense below 156 feet in DR 84-7 and below 192 feet in DH 84-5. The neutron log indicates that fractures are closed (non-water bearing) below 182 feet in DH84 .. ~7, and below 187 feet in DH84-5 .. 5.4 Groundwater Groundwater in the Downstream Portals Area generally occurs 40 to 80 feet below the ground surface (Exhibit 12). Artesian flow of one gpm occurs at borehole DH84-8, with an elevation head approximately equal to the collar elevation of the borehole, El. + 1675 (Exhibit 13). - The presence of discontinuous permafrost, discussed below in Section 5.5, may affect groundwater in this area by creating local perched or confined conditions. 50314/5 840725 5-5 - 1 1 1 I I ~ " . ~7< ~:· . -'",.. .... ', (> 5.5 Permafrost Permafrost conditions have been recognized in tha south abutment of the Watana damsite in previous investigations (Corps of Engineers, 1978; Acres American, Incc, 1980-1981). No evidence of permafrost had been noted in the north abutment, however, with the exception of one instrumented borehole, BH-6, which was drilled beneath the north bank of the river from ground El. 1608.8 feet. In the current investigation, permafrost conditions were encountered in three boreholes drilled from the lower part of the north abutment. Partially ice-filled fractures, 1/8 to 3/4 inch wide were recovered in core from DH84-3 at a depth of 8.0 to .~7.3 feet. Trace~ of ice were also recovered from DH84-8 at a depth of 18.0 to 54.0 feet. Trace ice was logged from a depth of 9.0 to 20.0 feet in DH84-6~ and ice formed in the borehole· blocking the piezometer pipe at a depth of 50-55 feet. The permafrost ice encounter~d in these boreholes appears to be local and discontinuous. Its occurrence in the lower portion of the north abutment is probably related to shade, due to the screening effect of the high, steep vallay walls of the south abutment. 50314/5 840725 5-6 - ·l .... --.·~-------··-----······«_,-............ -.......... . ' '· l t •···~· ----1 1 1 '·I ,,{~ ,m 1 ,. I I I 6.1 6.0 INVESTIGATIONS IN AREA OF UHDEKGROUMD PO~mRHOUSE {Design Refinement Le>cation) Introduction 6.1.1 Previous Work . Previous work in the area of the Underground Powerhouse was conducted by Acres American, Inc., in 1981: with the drilling of two 950-foot deep boreholes, BH-3 and BH-4. Both boreholes were directed to proposed chambers approximately 500 feet northwest of the current, FERC license design refinement location for the underground powerhouse. Two relatively shallow boreholes, 200 to 300 feet deep, were also drilled in the vicinity by the Corps of Engineers (1978). These holes (DH-10 and DH- 11) are located approximately 60 feet northeast of the current program borehole, DH84-2. Previous seismic work, 1980-1982, also crossed the area but is limited to near surface refraction profiling. Borings BH-3 and BH-4 encountered sound rock with areas of fracturing and alteration but nothing to preclude siting underground chambers within this portion of the abutment. The reorientation and relocation of the power house for the design refinement location was done so that the dominant structural trends of N50W would be intersected perpendicularly by the long walls of the major caverns. The initial orientation bisected the dominant and secondary joint sets. 6.1.2 Scope of Current Investigations The current program to obtain basic geologic information in the Underground Powerho.use Area consisted of drilling and testing one 765-foot deep, 50314/6 840725 6-1 --....... -..... .. :_] I inclined borehole. The borehole was c.rilled on a bearing of N25E, parallel to the long axes of the proposed chambers, and was inclined 30 degrees from vertical .. 6.2 Overburden 6.2.1 General Description Approximately 12.5 feet of coarse overburden was encountered in borehole D!i84-2. Similar shallow overburden, ranging from 10.5 to 25.0 feet . l.n thickness was reported in the four other boreholes in the immediate area (DH-10, {ind -11; and BH-3, and -4). The materials are genera.lly described as gravelly, pebbly sands with occasional boulders to 2.0 feet diameter. 6.3 Bedrock 6.3.1 Bedroc~ Topographl Refraction seismic data and the borehole data in the immediate area indicate that the top of bedrock generally lies at a depth of 25 feet or less. 6.3.2 Lithology and Rock Quality The current borehole, DH84-2, encountered diorite and quartz diorite with minor felsic intrusions$ As in other boreholes at the site, the rock mass shows varying degrees of hydrothermal alteration and fractu~ing, but the majority of the rock mass is hard a.nd strong. RQD values in the lower portion of the borehole, and specifically in the underground chamber area are good to excellent (see Exhibit 16). Similar conditions were also encountered at cavern level in nearby borehole BH-3. 50314/6 840725 6-2 , ~J, fl: ~ 6 .. 3.3 Structure · 1 · s tr ctur ~1 featu ... es were encountered 1n No indications of maJOr geo og1c u .;& ~ DH84-2. Discrete planar shears, slickensided joints, fractured zones, and associated alteration zones and clay filled fractures are present locally, however the rock maas in the area of the underground powerhouse appears to be generally excellent. 6.3.4 Alteration Zones Slight alteration of the rock mass is quite common in DH84-2, with a characteristic red color in large portions of the groundmass. Deeply altered zones, however, characterized by significant decrease in rock strength are limited in distribution, and generally involve zones of 2 to 3 feet or less in thickness. 6.3.5 Weatheri~ Surface weathering in borehole DH84-2 was primarily limited to iron-staining in zones of fracturing. No zone of decomposed rock was encountered as in borings on th~ southwest side of the Fins area. The deepest occurrence of significant weathering in DH84-2 was at a vertical depth of 59.0 feet. 6.3.6 Hydraulic Pressure Test Results Hydraulic pressure test r€sul ts for the Underground Powerhouse borehole, DH84-2) are presented in tabular form in Appendix C and in graphic form on Exhibit 16. The majority of the testing indicated very low permeability. Within the area of the powerhouse cavern, Lugeon values were in the range of 0. 0 to 0.4. Lugeons varied to a maximum value of 5.5 in the upper portion of the hole .. 50314/6 840725 l t .... 6-3 - ! 1m tJ Similarly, low permeability values were obtq,ined when borehole BH-3 was tested. This hole was tested at ten foot intervals w'ith the exception of depths 471 to 520 feet, 110-121 feet and 0-34 feet where no tests were completed because of hole conditons. The vast majority of the remaining test values were in the range of lo-5 to lo-7 em/ sec. No high take zones were identified. 6.3.7 Geophysical Logging Results Borehole geophysical logs run in DH 84-2 to a depth of 626 feet vertically below ground surface indicate that fractures are very tight and much less frequent below a depth of 295 feet. The density log for depths below 295 feet is relatively uniform and shows the diorite to be quite dense. 6.4 Groundwater Bedrock groundwater level is monitored at two depths in borehole DH84-2. The data indicate tha~ the groundwat,er table occurs 25 to 50 feet below ground surface (Exhibit 16). Artesian flows of approximately 1.0 to 1~5 gpm were noted in DH84-2 during tests ~n the lower portion of the borehole. The slight flow originates from depth interval 570 to 660 (El.l530 to 1452), in the upper levels of the proposed chamber~ pie~ometer installed (Appendix F). 6.5 Permafrost Total elevation head indicated by the pneumatic at elevation 1515 feet is approximately El.2070 No ~ce was noted in any of the core recovered from DH84.-2 and no other indications of permafrost conditions were encountered during drilling, testing or monitoring. Neighboring boreholes BH-3, BH-4, DH-10, and DH-11 also encountered no indications of permafrost. 50314/6 840725 6-4 -- ' ll·· .. ··-.·-j.r · ... ' '!~') l I 'i _.~~ l- i' \ \ I, I (\ <.; : 0 6.6 Foundation Evaluation Initial indications of the general foundation conditions in the area of the proposed Underground Powerhouse are quite favorable. The rock is generally sound and massive, and no major shears, faults or alteration zones were etcountered in DH84-2. The volumes of water to be handled by drainage and pump~ng during construction are expected to be low, based on the low permeability test values in the cavern area. 50314/6 840725 6-5 .;ae&$44iW .... 0 --~·-;e·--, • .,.,,. ·. ,, . ' ·r ! ' i ; l.":V I ' ' L ....__, ·I· ' t;:J ~; ' ' ! ! . ' ' i ' t 'I' \t'j REFERENCES Harza-Ebasco Susitna Joint Venture, Watana Development, Winter 1983 Geotechnical Exploration Program, 1983. Acres American Incorporated, Susitna Hydroelectric Project, 1980-81 Geotechnical Report, 1981. Acres American Incorporated, ~usitna Hydroelectric Project, 1982 Supplemen~ to the 1980-81 Geotechnical Report, 1982. Acres American Incorporated, Susitna Hydroelectric Project, Feasibilitr Report, 1982. U.S. Army Cor.ps of Engineers, Hydroelectric Power and Related Purposes, Upper Susitna River Basin, Southcentral Railbelt Area, Alaska, Final Feasibility Report, 1978. 50314/REF 840725 '' l '~ l ' i m X ::I: -m ·--1 (/J .~ " " l j l.OCATION t4N' l l 1 1 ,• l 1 ~ ~-.. : .· ,. ·.~:· . .i'•el WlJJ,tUI ...... "·'.:. ~ 0 U) SCALI ~-· __ _j I ALASK;~ POWER AUTHORITY WATANA DAM AND RESERVOIR PROJECT LOCATION MAP ltQ.wA. EXHIBIT 1 l I I I I I r I ') 1 1 l l I -, --; j \.;," i '11'7 fi,; 1' l' u J ;!' i IJ .'!!v IJ 11 t. t~ ~ ·~' ~ ~ ~ N I .·' ·--/ SU311'NA PROJECT DAWSITES VICINITY l1AP l 0 .l:z=:: 8 MILES SCALE~ d l .. ,. "\ j ; ' j' ·-' f rFINS AREA-EXPLORATION PLAN (EXHIBIT 6) ,..__ -- -. NOTEs: I. BASE MAP FROM 197B CORPS OF E;IGI~JEERS I" • 200' DAMSITE TOPOGRAPHY, 2. OAM LAYOUT FROM •suSITNA HYDROELECTRIC PROJECT, BEFORE THE FEDERAL ENERGY REGULATORY COMMISSION -APPLICATION FOR LICENSE FOR MAJOR PROJECT~ PREPARED BY ACRES AMERICAN, 11-!C., FEBRUARY 1983 0 1000 fOOO FEET Sr.AL£~ ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PRO.IECT WATANA OM.4 AND RESERVOIR SITE PLAN AND V~CINITY MAP OATt .M.Y 1984 llfi:AWIU tiO EXHISIT 2 1 I I I I ]I ,. I' .. ,..,, .. , . . . - .· i ... .•. _ . .-"'-... ~- ~~···""""- .~---:: •!, .. ---. .._f.~~.'...O b:.~~-DOWNSTREAM '. --------------------------------~----------------~ rSPILLWAY I· . -;·· .. n· ... "" CREST OF DAM___/ "'t EL.2210 -\'r ,..\,t .() .~t 1··~ .(y ,. < 1 !.· / f / N 3,2lHi,OCO' .. • SEE IJ<JRftiOLE: lOC:ATION OETI\IL -!:.0 v '\ \ / - r ~ 0 -200 ··4oo FEET SCALE ~r-'!·?~~Siiiiiiiiiiiii~' \1<;~) •• ,. i -~~or-----~----~----------------------------~ ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT WATANA DAM AND RESERVOIR 1984 GEOTECHNIC.AL PROGRAM BOREHOLE LOCATION PLAN JULY 1DU OAA*IffO NO EXHIBIT 3 ., 'I r .~ n ll n h TI n u ~ L ' ~ ....._.- ~ i • < I ~11 , .. ., !'li ;, w l'' t~ n L'1 ,1 H ... d I u ~ I ~ PREVIOUS EXPLORATION BOREHOLES AND TEST PITS .· 1978 CORPS OF ENGINEERS ROTARY DRILL BORING 1978 CORPS OF ENGINEERS INCLINED CORE HOLE 19BC•BI ACRES AMERICAN,INC;,INCUNED CORE HOLE 1981 ACRES A,IIIERICAN,IN~. BACKHOE TEST PIT 1982 ACRES AMERICAN,INC.,ROTARY/CORE OORlNG 19113 HARZA·E,.ASCO, HAMMER !lORING 1983 HARZA-EB.C: .>CO, CORE HOLE INCLINED BORING WITH DIP ANGLE OF 45• GEOPtiYSICAL SURVEYS --r~ ~ f.j.,;_' !_:1.) ~ SEISMIC R!::FRACTION JURVEY Ll 1975 DAMES a MOORE 19711 SHAHNON 8 WILCDN 1980 ·81 WOODWARD· CLYDE CONSULTANTS 1982 WOOOWARD-C!..YDE CONSULTANTS SEISMIC REFRACTION SURVEY LINE 1983 HARZA·EBASCO/HARDING LAWSON ASSOC. GROUND RADAR SURVF.Y LIHE 1983 HARZA·EBASCO/HARDING LAWSON ASSOC. .. ~···-/ • oO ., :.: 1984 GEOTECHNICAL EXPLORATION PROGRAM ~ CD ® @ DH84-I ---~- ................ ".'''"" 198<4 HARZA·EBASCO INCLINED BOREHOLE 00\'/NSTREAM PORTALS AREA-GEOLOGIC MAP (l:XHIBIT 11) RIGHT ABUTMENT-GEOLOGIC MAP (EXHIBIT 14) FINS OUTCROP AREA -GEOLOGIC MAP (EXHIBIT 5) ',• SCALE O~e--"~50iO;;i2zOO~::s;;;t5;;;;4i;iOO FEET A1..ASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT WATANA OAM /.NO RESERVOIR DAM SITE ARE A EXPLORATION PLAN OAlt ANCHOAAOE. ALASKA JULY ISS4 DfiA"IIfG HO EXHIBIT 4 I ,. j ! \ \ l i I + ~ l j ,, .. t• i I ~~ .• JOINT PLOT FINS AREA lb124 LEGEND LlniOLOGY: o ~~aF~&Lt~s~~~OSITS:INCLUDES ALLUVIUM 0 g~~lj.)Jg1b~~~~UDES QUARTZ DIORITE/ D ANDESITE PORPHYRY -x-FELSIC DIKE CONTACTS: -BAEDROCK CONTACT, DASHED WHERE PPROXIMATE -BWEDROCK/SURFICIAL DEPOSITS DASHED HERE APPROXIMATE ' STRUCTURE: ~ SHEAR ZONE;WIDTH GREATER THAN 5FEE'I: ~ EXTENSIONS SHOWN BY OASHE!I ' __.... SHEAR ZC'IE;WIDTH 1 TO 5 f'EET ' EXTENSIONS SHOWN BY DASHES 1 p SHEAR ~ FRACTURE ZONE, WIDTH GREATER TH.AN 1::2221 5 FEET; EXTENSIONS SHOWN BY DASHES #" FRACTURE ZONE, Wi!lTH I TO 5 FEET. ,.. EXTENSIONS SHOWil BY DASHES WHERE KNOWN OR INFERRED 7070 f 1/ ;f JOINTS i INCLINEO,OPEN INCLINED, VERTICAL OTHER: -···-RIV~R EDGE ...f.B.EVIOUS EXPLORATION BOREHOLES: 1978 CCRPS OF ENGINEERS INCLINED CORE HOLf: , I•' • 1980-81 ACRES AMERICAN, INC., INCLINED CORE HOLE •. ,[U~· 1963 HARZA·E6ASCO, HAMMER BORING ""•' 1 HARZ A • EBASCO CORE HOLE GEOPHYSICAL SURVEYS: SEISMIC REFRACTION SURVEY LINE 1978 SHANNON a WILSON 1960 WOODWARD-CLYDE CONSULTANTS 1981 WOODWARD-CLYDE CONSULTANTS 1962 WOODWARD-CLYDE CONSULTANTS 1963 HARZA•EBASCO/HAROING LAWSON ASSOC. GROUND RADAR SURVEY UN( 1963 HARZA•EBASCO/HAROIHG LAWSON ASSOC NOTES: L COMPOSITE GEOLOGIC MAP BASED ON !lATA FROM ~Ofri_s6 ~; 11EtRGi~f:.W,;J~b~t:fe~RES AMERICAN,INC,, 2. BASE MAP FROM 1978 CORPS OF ENGINEERS I"• 200' DAMSITE TOPOGRAPHY 3. JOINT PLOT CONTOURS ARE THE PERCENT OF iW~J~3 :~~J ~ !j_F AREA;CONTOUR INTERVALS 0""'!!!!!!!!!5j;O;;;;;;iiiiiji?O FEET SCALE E . ALASKA POWER AUTHORITY .~. =--·:~~~"iJ§}rFA H~~Ro§!:fr'U1'<J:"i'Ro~c.::..r:..-·----• WATANA DAM AND RESERVOIR FINS OUTCROP AREA GEOLOGIC MAP -~-·-------·- EXHIBIT 5 r n • " ij u ~ ;i , I ~ ~ ;i_ ' ,_~ n JJ , n '\ '1 • F . . ' '!; l ; I~. ' ' 1 ., ' \ ()fJR·22 E~,2185 \ ·' ';.: PREVIOUS EXPLORATION BOREHOLES AND TEST PITS (•) Dl?-19 0 lJH-1 cJ' BH-5 -TPR-11 0 AH•IM?2 @ HOB:3·1 (:) OHB:3·1 (!I 1\, DHB4•1 1978 CORPS OF ENGINEERS ROTARY DRIU. BORING 1978 COR:>S OF ENGINEERS INCLINED CORE HOLE 1590·81 ACRES AMERICJ\1'1, IN~ INCLINED CORE HOLE 19()1 ACRES AMERICAN, INC., BACKHOE TEST PIT 1982 ACRES AMERICAN, INC., ROTARY/CORE BORING 1983 HARZA·EBASCO, HAMMER BORING 1983 HARZA-EBASCO,CORE HOLE INCLINED BORING WITH DIP ANGLE OF 45• 1984 HARZA -EBASCO INCLINED BOREll OLE GEOPHYSICAL SURVEYS ~·-41 OM·C SW-1 SL80-1 $£ 81-2 SL 82·1 ~ sa3-5 8-·-8 R83-I SEISMIC REFRACTION SURVEY LINE 19'/5 DAMES a MOORE 1978 SHANNON a WILSON 1980 WOODWARD• CLYDE CONSULTANTS I9BI WOODWARD-CLYDE CONSULTANTS 1982 WOODWARO•CLYOE CONSULTANTS SEISMIC REFRACTION SURVEY LINE 1983 HARZA•EaASCO/HARDING LAWSON ASSOC. GROUND RADAR SURVEY LINE 19'~' HAilZA·EBASCO/HARDING LAWSON ASSOC. N<ITE: 1984 EXPLORATIO!l IN THE FINS MEA IS SHOWU IN MORE DETAIL IN EXHIBIT 3, ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT WATAHA DAM AND RESERVOIR FINS AREA EXPLORATION PLAN EXHIBIT e l 1 l J [ J l i • .,1 •.] J I I I ------~~--~·-----..... ~----~- . ' , . (' ., () F' ,:; ,. <r t• • w ,.;} LEGEND LITHOLOGY• F:J:'~~:~~~ r--~J EXPLORATION: 0 .,. CONTOURS• OTHER: NOTES: tONf: OF HIGIILY WEATHERED TO DECOMPOSED aEOROCK, APF'IOXIMATE BEDROCK OUTCROP, UNDIFFERENTIATED AND APPROXIMATE 1994 EXPLORATION PROGRAM BOREHOLE ROTMY, AUGER, P.ND HAMMER BOREHOLES SEISMIC REFRACTION SURVEY LINE RESERVOIR LEVEL, 2185 FEET TOPOGRAPHY, CONTOUR INTERVAL IOO FEET TOP OF BEDROCK, CON'rOUR INTERVAL 50 FEET DOT INDICATES SEISMIC CONTROL POINT FOR TOP OF ROCK 1. ONlY THOSE BOREHOLES WHICH ENCOUNTERED OR PENETRATED BEDROCI{ ARE SHOWN MODIFIED AFTER ACRES AMERICAN, INC, 1982 SEE FIO.URE 6.7 3 BASE M"P FROM 1978 CORPS ,]F ~NGINEERS l'ti200'0AMSITE TOPOGRAPHY 4 PREVIOUS BORINGS BY CORPS Of ENGINEERS, 19781 At.:RES AME.RlCAN, INC., 10~1>-821 AND HARZA • oBASCO. 1983. 5 SEISMIC REFRACTION SURVEY LINES BY DAMES AND MOORE, 19751 SHANNON AHD WilSON. 1978; AND WOOOWAAO·CL YOE CONSULT,.NTS, 1980•82 1000 SCALE~--· 2000 FEET =;;a ALASKA! POWER AUTHORITY . SUSITNA HYDAOELECTRIC-PROJE'i::T ·_.·· WATAtiA OAM AND RESERVOIR 'FINS AREA BEDROCK CONTOUR MAP -~~~-~"-.. _,_,_., , __ _ JULY 1984 .,...,.,.., •o EXtiiBIT 7 """ ANCHOOAOE, AV.SK.\ 2400 ~ Ul Ul 2200 ~ 2000 z 0 ;:: 1800 < > Ul 1600 ..... w 1400 1 I 2400 2300 .J 2200 2100 J r.: 2000 w w ~ z 1900 0 ;:: < > l.t ;.J w 1800 1700 J 1800 1500 HOO I O+OO 10+00 ~I ~I r OVERBURDEN·' _ TOP OF BEDROCK·~~-L----~ -..,ll .. liiiil=-n~------_.,.----ZONE OF HIGHLY WEATHERED TO DECOMPOSED DIORITE DIORITE SUITE 20+00 30+00 40+00 50+00 60+00 GEOLOGIC PROFILE A-A TRUE SCI\LE ~I 70+00 f OVERBURDEN J .. ~~-~-:· TILL / ~ -- : _.,......-.' T.D,252,fl----·: __ ......., __ _ -~ ,· TOP OF BEDROCK~ / T.O. 248.3 L. ZONE OF HIGHLY WEATHERED ; TO DECOMPOSED DIORITE / _./ // r.o. 497.5 .......----~----/ ---........ -DIORITE SUITE: ~ \ --~ , _ _,.... Generally fresh, hard, strong O+OO 10+00 20+00 30+00 4o+oo 50+00 6D+OO 1o+oo GEOLOGIC PROFILE A-A SCALE EXAGGERATED (V TO 1 H ~I ~I r MAXIMUM NORMAL OPERATING POOL EL. 2165 2400 ..l.......o::!;..--· -·--~--;::: 2200 w w !!. FINS OUTCROP 2000 z 0 -1800 t= ~ 1800 Ul ..... Ul 1400 BO+OO so+oo 100+00 2400 2300 '2200 2100 2000 ~ Ul !!; :z 1900 0 t=. < --FINS OUTCROP > Ul .... 1800 Ul 1700 1600 1500 1400 80+00 BO+OO 100+00 SOIL ~ ~ k=··:e.::=j [:;·:;.:-:·:1 ROCK CONTACTS ~ OTHER• -\1- -s )-s s Fz A NOTES: CD ® G> ® @ ® (i) ® ® LEGEND OUTWASH TILL LACUSTRINE ALLUVIUM DIORITE SUITE; DIORITE, OUARTZ DIORITE, GRANOOIOII11t DIORITE SUITE; SEVERELY WEATiiERED ALTERED DIORITE, MODERATELY TO SEVERELY ALT£~ED MONZONITE TO GRANITE ANDESITE PORPHYRY FELSIC SURFICIAL DEPOSIT TOP OF BEDROCK BEDROCK, DOTTED WHERE APPROXIMATE GROUNDWATER TABLE WITH DATA POINT JIA.Y 3, 1984 FEATURE LESS THAN 3 FEET WIDE FEATURE GREATER THAN 3 FEET WIDE SHEAR CLOSELY TO VERY CLOSELY FRACTURED FRACTURE ZONE(VERY CLOSELY FRACTURED) ALTERED, WEAK SECTION LOCATION SHOWN O)i EXHIBIT G. SURFACE PROFILE FROM I"• 2001 TOPOGRAPHIC MAP; COI!PS OF ENGINEERS,I97B. FOR DETAILED BOIIEHOI.E DESCRIPTIONS, SEE EXPLORATION LOG!I IN APPENDIX A • FOR GROUNDWATER DATA SEE APPENDIX F. CHANGES IN LITHOLOGY AilE SHOWN FOR THICKNESSES OJIIEATER THMI 4 FEET. TOP OF ROCK PROFILE ADJUSTED TO FIT THE BEDROCK ELEVATION IN EACH I'ROJECTED BOREHOLE FOR GEOLOGIC IIOTES ON DHB4 -4A, SEE FINS AREA GEOLOGIC PROFILE B-B ELEVATION OF GROUNDWATER TABLE IN Dll-111 IS FROM AUG. I978.1NSTRUMENTATION MOliiTOftlNG INDICATES LITTLE CHANGE IN GROUNDWATER TAIILE AFTER WATER LEVELS HAVE STAil.IZED, THEREFORE DATA FROM DR-IB IS CONSIOEIIED VALID. ALL BOREHOLES ARE ~ROJECTED. THE OISTkNCE PROJECTED IS FROM THE BOREHOLE COLLAR, ALASKA POWER AUTHORITY SUS~TNA HYDROELECT.ill9 PAc..::Oo.:J:::.EC=..T;..._ ___ 1 WATAHA DAM AND RESERVOIR FINS AREA GEOLOGIC PROFILE A-A ~·001!~ JUJitM 101"11' YI'"IIJttt AP~A 1\1(0 """ ANCiiQRAG£, .ALA$!( A (.'ftAllolfWQ.ffO JULY 1084 EXHIBIT 8 2200 2100 2000 1900 t Ul !;; z 1800 \0 ;:: < > w -' w 1700 1 1600 151.1) ] j 1400 I 1300 I sw DH84-4A (PROJ. 95 FT.) C:ONE OF HIGHLY WEATHERED TO DECOMPOSED DIORITE TO 254.0 FT. o+oo 1+00 DH64-10 (PROJ, 100 l'T) 2+00 3+00 NE 4+00 HD63-2 !PRO,;. 140FT.) r GROUND SURF.\CE DH84-1 (PROJ. 140 FT.) -=---=~-u:t--~O~U;;TI;~A;:;S;Htl._-~~--·"~ .~-~~-~----· ~ ··~--,"~'\)---, , <-~"·---~_, ,-1.· F;~g¢~E 5+00 OUTWASH _. ---_.....--l ' ZONE ---~It"" / I FRACTURE ZONE .... ..____ -::.-..::::_._ ... ..,_.... I CLOSE TO --Jl1\al[11.-----,'L V.CLOSELY FRACTURED DIORITE SUITE: Generally fresh, hard, strong SHEAR f ~SEVERELY WEATHERED I I ANDESITE ' ANDESITE PORPHYRY ll>IKE I PORPHYRY DIKE ---CLOSE TO V. CLOSF.L Y FRACTURED ·-ALTERATION ZONE ·• CLOSELY TO V. CLOSELY FRACTURED I CLOSE TO v. CLOSELY FRACTURED ·-FRACTURE ZONE --MASSIVE T .0 698.5 FT. ~-CLOSE TO V CLOSELY FflACTURtM .GHtAR T.O. 848.5 FT 6+00 7+00 B+OO B+OO 10+00 11+00 GEOLOGIC SECTION B-B -2200 2100 2000 1900 1600 1700 1600 1500 ·-1400 1300 E w !;; z 0 j:: < > w ..J w ROCKi ~ e rillilll ~ CONTACTS• OTHER• -\1.- -sHEA" LEGEND OUTWASH TILL DIORITE SUITE; DIORITE, QIJ>\RTZ DIORifE, GRANODIORITE DIORITE SUITE; SEVERELY WEATHERED TO DECO! 'OSED ALTERED DIORITE; MODERATELY TO SEVERELY ALTERED MONZONITE TO GRANITE ANDESITE PORPHYRY SURFICIAL DEPOSIT TOP OF BEDROCK BEDROCK, DOTIED WHERE APPflOXIMATE GROUNDWATER TABLE WITH DATA POINT JULY 3,1984 FEATURE LESS THAN 3 FEET WIDE )-N..n~ATIOH FEATURE GREATER THAN 3 FEET WIDE <i!f}i>--GEOLOGIC FEATURE, SEE ACRES AMERICAN, 1982 NOTES' <D ® 0 0 0 SECTION LOCATION SHOWo'l ON EXHIBIT 6. SURFACE PROFILE FROM I"• 200' TOPOGRAPHIC MAP; CORPS OF ENGINEES ,1978 FOR DETAILED BOREHOLE DESCRIPTIONS, SEE EXPLORATION LOGS Ill APPENDIX A FOR GROUNDWATER DATA SEE APPENDIX F. CHANGES IN LITHOLOGY ARE SHOWN GRAPHICALLY FOR THICKNESSES GREATER THAN 4 FEET 0~~~5!§0;;;;;;,;~100 FEET SCALE E!! ::J ALASKA POWER AUTHORITY SUSITNA HVDROI:LEC'fRIC PROJECT WATANA OIIM AND RESERVOIR FINS AREA GEOLOGIC SECTION B-B DATE ~1t(.'ifjO 1\NCHO!lAOF, ALASKA JULY 1964 EXHIBIT 9 l J ] J J I 0.0'·72.4' OVERBURDEN ~~~~~EL!:_;.:.J2~1~3!2.~5 EL 2 :Y, EL. 2135.1 ' .,. JULY 1984 ~·~ -.· 3 JULY 1964 • I [PP) 3 JULy 1984-1' I SPl {FPl ZONE OF DECOMPOSED DIORITE, MODERATELY WEATHJ:RED TO SEVEREt Y WEATHERED, VERY SOFT TO SLIGHTL V HARD, CRYSTAL fABRIC INTACT OU.ARTZ DIORITE MOOERATEL V WEATHERED TO fRESH, MOO ERA TEL Y H.,RO TO STRONG, LOCAL SHEARS/FRACT1JRE ZONES AND ALTERATION ZONES 0.0'•11G.9' OVERBURDEN MOSTLY CLAYEY, SANDY SILT VERY DENSE ZONE OF PECOMPOSED DIORITE, SEVERELY WEATHERED OUACTZ DIORITE. MODERATELY WEATHERED TO fRESH MOOERAT:L Y STRONG TO STRONG, VARIABLE FRACTURING, lOCAL ALTERATION AND SHEARS EL.214~ 3 JlJLY .904 -~ (SP&PPl QUARTZ DIORITE fRESH HARD TO VERY HARD STRONG DH84-10· GROUND SURF ACE El., 2161.5 o.o'• 61.6 OVERBURDEN MOSTLY SILTY SAND VERY DENSE ZONE OF DECOMPOSED DIORITE, SEVEREL 'f WEATHERED, SOFT, WEA~. fRIABLE, CRYSTAL FABRIC INTACT DiO;illE,MODERA TELv ·WEATHEREo;-- SLIGHTLY TO MODERATELY HARD, WEAK TO MODERATELY STRONG, _ J:.Qi:AJ:..§H§M!S __ _ DIORITE, OUARTZ DIORITE, ANDESITE UNWEATHERED. VERY HARD TO HARD, STRONG I l ~~E~L~·~20~7~0~.9--------­I 3 JULY 1984 EL. 212D;!l-~ a JULY 190/ I ... "' I- I ,.;'! f GROU>lO SURFACE EL 21~3.1 ANDESITE PORPHYRY AND DIORITE, MODERATELY TO CLOSELY FRACTURED, LOCAL AL TERAT!DN ZOHES LEGIEND: 100 ROO/CORE RECOVERY SCALE lomm0--r-150h-li~:E~T[TOP OF R~ 14.7 FT DIORITE AND QUARTZ OIORITE, LOCAL GRANITIC AND FELSIC INTRUSIONS, ROCK MASS GENEAALL Y HARD AIJO STRONG, Mr·nERATEL V FRACTURED, LOCAL SHEARS .'f___El:.!?!~----·~_R~ V 2 JULY 1g94 DATE MEASURED ·-CORE RECOVER'( ROD (ROCK QUALITY DESIGNATION) EL. 214M,;t 3 JULY 1984 I LOCAL FRACTUR!; ZONES TO 12 FT. WIDTH LOCAL SEVERELY ALTERED ZONES TO 8 FT. WIDTH ~214~1.6~------­T 3 JULY 1984 ~GROUND SURFACE EL. 2161.5 TOP OF ROCK 148.2 FT. INTERVAL lUGEON T VALUE •· ····-2.0 1 FRACTURE ZONE INTERVAL r.t--+--1-PIEZOMETER INSTALLATION SP • STANDPIPE PIEZOMETCR PP • PNEUMATIC PIEZOMETER ~---·--OIORITE,SEVERELY ALTERED, WEA~ (In oxcosa at 3.0 It, drlllod longth J NOTES; ZONe OFoECoMPOsED DiORiTE.--- - -- MODERATELY TO SEVERELY WEATHERED. I. ALL BOREHOLES IN ~INS AREA INCLINED 35' FROM VERTICAL 2. DESCRIPTIVE TERMINOLOGY DEFINED IN APPENDIX A, CORE LOGS DIORITE, DIORITE, VERY SOFT TO SLIQHTL Y HARD, LOCALLY FRIABLE', _CI!!S!:il~Bl!!Q I!IT,AC_L ____ _ FRESH, HARD, STRONG MODERATELY TO VERY CLOSELY FRACTURED, MINOR ALTERATION, LOCAL SHEARS MOOERATEL Y TO SEVERELY ALTERED, VARIABLE STRENGTH AND HARDNESS ------------ DIORITE AND OUARTZ DIORITE, MDDE.RATELY TO V"RY CLOSELY FRACTUnEO. LOCAL SHEARS, SLIGHT TO MODERATE AlTERATION, LOCAL ZONES OF SEVERE ALTERATION (3.0 FT. MAX LENGTH) 0 50 100 SCAUt ._1 ..1--'-1-J''-''-'-' _.__._ ... ,_,! FEET ALASKA POWER AUTHORITY . s~slrf!F iivoRoe_@qiRl£=~_FfQ:.Jeci-·=·-- wArANA OAM ANO RESERVOIR FINS AREA GRAPHIC LOGS ~~~~:=-~=4-1 :~: 9 10 •NCHORAOE, ALASK:r JU.Y 1904 EXHIBIT 10 I f 1984 GEOTECHNICAL EXPLORATION PROGRAM ~H84·5 !984 HARZA-EBASCO INCLINED BOREHOLE PREVIOUS EXPLORATION BOREHOLES: 191!0·81 ACRES AMERICAN, INC., INCLINED CORE liOt.E ··' 1983 HARZA·E8ASCO, HAMMER BORING GEOPHYSICAL SURVEYS: SEISMIC REFRAC710N SURVEY UNE ;.ct , ' 1978 SHANNON a WILSON ;c.(; ' 1980 WOODWARO•CLYDE CONSULTANTS ~,.0,, , 1981 W()()()WARD-CLYDE I.:ONSULTANTS 1982 \I'OODWARD·CLYDE CONSULTANTS ''' · •< 1963 HARZA·EBASCO/HAROING LAWSON ASSOC ' GRO:JNO RADAR SUfiVEY UNE ,;;;; 4 1983 HARZA·£8ASCD/HAROING t.AWSCN ASSOC ~;==- :l JOINT t'~OT COWt ')!ReAM PORTALS AREA N•294 sosirN4 ~~-.,-. Rtv~IT -.,_ ". ~. ~' ' LEGEND LITHOLOGY: L.=! CJ D -x- SURFICIAL DEPOSITS: INCLUDES ALLUVIUM AND COLLUVIUM DIORITE; INCLUDES CUARTZ DIORITE I GRANODIORITE ANDESITE PORPHYRY FELSIC DIKE CONTACTS: --~~~~g~~M~~~TACT, DASHED WHERE -BEDROCK /SURFICIAL DEPOSITS, DASHED WHERE APPROXIMATE STRUCTURE: SHEAR ZONE;WIDTH GREATER THAN 5 fEET, EXTENSIONS SHOWN BY DASHES SHEAR ZONE)W!Q,TH I TO 5 FEET, EXTENSIONS SHOWN BY DASHES SHEAR FRACTURE ZONE,WIDTH GREATER 1'HAN 5 FEET; EXTENSIONS SHOWN BY DASHES FRACTURE ZONE, WIDTH I TO 5 FEET; EXTENSIONS SHOWN BY DASHES WHERE KNOWN OR INFERRED JOINTSJINC!.INED, OPEN INCLINED, VERTICAL ~g~~~g~C~~RP,TO 20 FEET HIGH,JOINT -\\"'-\\" RIDGE CREST OF SLUMP BLOCK OTHER: t j LINE OF SECTION ~ SPRIN$ NOTES' l COMPOSITE GEOLOGIC MAP BASED•Otl DATA FROM 'CORP'.l OF ENGINEERS,I97Bi ACRES AMf.R 1CAN,INC., I9BO·S2; HARZA·ESASCO,I983 2. GEOLOGIC SECTIONS ARE SHOWN ON EXHIBIT Ia ~. BASE MAP FROM 1978 CORPS ClF ENGINEERS I" • 200' DAMSITE 1'0POGRAPHY 4. JOINT PLOT CONTOURS ARE THE PERCENT OF JOINTS PER 1% OF AREA; CONTOUR INTERVAL OF 113,517 "/, 0 50 SCALE,_, ___ 100 FEET I ALASKA POWER AUTHORITY _. _ _§g~J:I'!'!J!!OE\J=C'@ip PROJECT·---1 WATANA DAM AND RESERVOIR DOWNSTREAM PORTAL'S AREA GEOLOGIC MAP a ~ e I I \l j I • I i ~ l I t::: Ul Ul ~ ~ 0 l= < > w ..... Ul NW ""l DH84-5 iffiOJ. 7Q fTJ 1700 1600 1500 1400 1300 1200 o+oo 1+00 2+00 t::: Ill w ~ z 0 l= < > 111 ..... w r · tlROUNO SURF ACE TD.~El3SH. \ ~SLHiHl TO \ ' MOD. Al.TEREO \ 3+00 4+00 5+00 G+OO 7+00 DH84-3 (PROJ. 20 fTl a+oo 9+1l0 GEOLOGIC SECTION D-D N ~I 1900 1 GI'!O\JND SU!lFACF. 1800 ., . i OH84-8 1700 fROZEN X :-.. DH84-6 10+00 11+00 .,j ~~ "' ,., "' "' (.'){ t..? SE ·1600 ··1700 1500 1400 1300 ·1200 12+00 1600 1500 \ ~;~[PRQJ 103FT) ·, "" -..; DH84-3 '-..""-.. ~ {PROJ30FTJ ~ TD.100l!FT. ........, -........._...._ FRO~~-'\ SUSITNA RIVER 1 H083-48 MOO WEATH ~ "'"'-....... / {PROJ, 30 FT J ;~-~ 'f I -·-······~-~ - ALTERATION .. ._ !1-MASSIVF.._ ----------- 1400 ._ ~ ALL1JV"JM I T D. 132.2 FT , -MASSIVE • f ---.1 TOP OF ROCK TD. jQS.O FT. 1300 1+00 3+00 4-tOO 5+00 6+00 7+00 8+00 9+00 GEOLOGIC SECTION F-F t::: w IJJ ~ z 0 i= < ,. ...:J .... UJ s 1900 1800 1700 t::: w ... !!; z 0 ··1600 i= •< > IJJ ..... w 1500 '1400 1300 10+00 t::: w IJJ ~ z 0 i= < > w .... w SOli:.; ROCK: ~ ~ N s 2000 ·2000 1900 1iiOO 1.800-1t.Oil 1700. ·1700 16Q();" /-GROUND SURFACE ·16(10 1500 T .tl. iG5.0 fT. .r SUSlTtiA RIVER 1500 I -9 1400 -;n~ ·1<400 ""1 ~ .... o+oo 1+00 2+00 3+:10 ;+oo 5+oo 6+00 7+00 C+OO GEOLOGIC SECTION E-E LEGEND NOTES: ALLUVIUM (l) ® DIORITE .SUITE; DIO!IITE ,QVAJITZ DIOIIIT£, GR.l!l()()IC.,mt. G) A'.TEREO DIORITE':;IIOOEIIATt:LY TO st~ElY ALTtl!fll @ ® r.eDNZOHITE TO GRANITE SECTION LOCATIONS SHOWH 011 EXHIBIT II SURFACE PROFILE FROM I" • 200' TOPOGRAFl!IC MAP; CORPS OF ENGINEER3,1171. FOR DETAILED IOIIEHOLE DESCIIIPTIOIII, SEE EXPLOIIATIOH LOGS IN APPEIIDIX 1... FOR GRO.UNOWATER DATA SEE APPEIIOIX F. CHMlGES IN LITHOLOGY ARE SHOWN GRAPHICALLY FOR THICKNESSES GREATER THAN ~FEET. t::: Ill Ill ~ z 0 ~ > w .... w STRUCTURE: @ ALL BOIIEHOL •ts ARE PROJECTED. THE IDENTIFIED DISTANCE IS TO THE BOIIEHOI.E COLLAR. ~ -·--··- CONTACTS: ~ OTHER: -\J.- -st£A" ]-ALTE"ATIOif ~ . SHEAR Z.ONE,WIOTH lTD !I FEET FRA'l:TURE ZONE, WJLWli GREATER Tll.AN ~ Fttt Fft .. ,CTUIIE ZOHE,WIOTH I'TO !I FEU TOP OF BEDROCK GROUNDWATER TAl'>l.lt \lll~ ~\11'._ N!IH'i' JULY 3,1$11-4 FEATURE LEU \'lU.t< ~ ¥'tH '11/IN. FEATURE OR(i<ft,R 'f~~-N M'ti~ 'Wrbl PEIIMAf'r.Q! t' Ill<,\.\ AYf •' '1'-'t ~N!Plf\• ; " '\i.t\Sl<A POW::R AUTHOiiUTY ~~r-:.nN~ H'I'IJROEL !@.'fulc'?'fia·JE-'""c'""'r----1 ~lANA DAM AM!> REIIERVOIR ~{1\\!NSTREAM PORTALS AREA I '<3~m.o ~1c ~c.~-:~~ .. ~·~ ~.=:-~. ~-~= <:~fj,l;.(I.,W.ii,A\0i!!Go ., 't •\.). V'-\4-HW..• lH .ltTtlfM-0 ut p.Aif t~:ote 4-;;·~~:Ae • .JUl..'{ "U l EXHmti' 12. ___ :;:u:::::·:~.;-.;:;.:;;::. ... ~--··~ ~·------ I EL 1481.6 ~ 2 JUI.Y 1984 I I I I II • [ STANO PIPE PIEZOMETER ] FLOWING 1.0 GPM 3 J\li.Y 1984 J 3 J\li.Y 1984 EL.1673.S ~ ] J J 'i I I II l DHS4-3 [ GROUND Sl.lllFACE E~. 1503,3 0.0•11.S OVERBUfltJEN TOP OF IIOCK 8.5 f1'. --------------OUARTZ DIORITE, MOO£RATELY TO SEVERELY WEATHERED, CLOSELY TO VEIIY ~OSELY fRACTURED. _ O~S..!Q!IA!:J! €:f!Lill> F~C.]!lE...§. T.!?_gT ~ .. fHL ~ I _y_ EL.164Jll._·"~--. 71 __ T 2 JUl. v 1984 DH84-8 j GROUND SURFACE EL 1671.1 0.0 • 8.5 OVERBURDEN DIORITE, CLOSELY TO MODERATELY FRACTURED, TRACES OF ICE IN FRACTURE:;, 18.0 TO 54.0 fT. LOCAl. AI. TERA TION ZOtlES I 01184-S DIORITE, HARD AND STRONG, LOCAL ALTERATION, DIORITE. GROUND SURFACE EL. 1725.6 0.0 ·15.1 OVERBURDION VERY CLOSELY FRACTURED, MODERATELY TO SEVERELY ALTERED VERY CLOSELY TO MODERAT~LY FRACTURED I / DH84-7 .,GROUND SURFACE EL. 1625.3 0.0 • 4.2 OVERBURDEN I ,'ll EL.l~S!'-'67~.5~--·----+--T 2 JULY 1984 I I ,1 I ~~ QUARTZ DIORITE THROUGHOUT HARD, FRESH, STRONG, MODERATELY TO VERY CLOSELY FRACTURED, LOCAL ZvNES OF SLIGHT TO MODERATE ALTERATION DIORITE, DH84-6 • GROUND SURfACE El.. 1521.4 0.0 • 9 0 OVERBURDEN TOP OF ROCK 9.0 FT ;------------ DICl'liTE, MODERATELY ALTERED VERY CLOSELY FRI\CTUIIEO, WEATHERED, LOCALLY ALTERED -I~ IN ~I~F~ ~ T~O.O FT _ CLOSELY TO VERY CLOSEL V FRACTURED, LOCAL ALTERATION, GENE<IALLY HARD AND STRONG LEGEND: VIATEA LEVEL DATE MEASURED ROO/CORE RECOVERY SC,LE 0 50 100 PERCENT LTOP OF ROCK lr..rJ--.-hrl 14.7FT CORE R':COVERY ROO (ROCK QUALITY DeSiGNATION) UITEAVI\L LUOEON T VALUE ·------2.0 .• -+11-1--1-FR ... CTURE ZONE INTERVAL 1 IIOTES: f.H--1--Ii-piEZOMETER INSTALLATION SP • STANDPIPE PIEZOMETER PP ·PNEUMATIC PIEZOMETEII '----DIO~ITE.SEVERELY fiLTERED, WE ... K (in •XCOII ol 3.0 It, drilled lonolh) 1. ALL BOREHOLES IN DOWNSTREAM ~ORT ALS AREA INCLINED 30'FROM VERTICAL 2. DESCRIPTIVE TERMINOLOGY DEFINED IN APPENDIX A, CORE LOOS 0 50 SCALE FEET ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT WATANA DAM AND RESEnVOIR DOWNSTREAM PORTALS AREA GRAPHIC LOGS BOREHOLES OH84-3,5,6,"f,8 G{!£001Ui\•~~ M1T~" }CIOI't y(fllfUitt' UIIROVCb ANCIIORACE', ALASKA JULY 1984 D'tA'III'IH.i ItO. EXHIBIT 13 I I J I I I j '• ] l I I I \ '\ ••. ·'t ~ . t \ ~.,-. \ Gl ) ·~·~ ..... .. \ -,,~ ___ .... ~ .. --.~ ~.: '-,. 1 .. -..;' 4~8: ~,.'!"'o'' -.,.._,.., ,_._..,__,. ___ "'!' ·+ w JOINT PLOT RIGHT ABUTEMENT N '1•1 l • ~ E / ,, LEGEND LITHOLOGY• D D D SURFICIAL DEPOSITS• INCLUDES ALLUVIUM AND COLLUVIUM DIORITE • INCLUDES QUARTZ DIORITE/ GRANODIORITE ANDESITE PORPHYRY CONTACTS• -BEDROCK CONTACT, DASHED WHERE APPROXIMATE -BEDROCK /SURFICIAL DEPOSITS, DASHED WHERE APPROXIMATE OTHER: A A t. jLINE OF SECTION 1984 GEOTECHNICAL EXPLORATION PROGRAM &~ CH>.Jol•l 1984 HARZA-EBASCO INCLINED BOREHOLE PR~VIOUS EXPLORATION BOREHOLES: ·~ .... ~-. 1 ~· f.lt~,e 1978 CORPS OF ENGINEERS ~IHED COllE HOLE 1900·81 ACRES AMERICAN,~ INCLINED CORE HOLE GEOPHYSICAL SURVEY• 'V' .tp SEISMIC REFRACTION SURVEY LINE -'Lt·l 3<.1)0·1 :_:.._ 8,' :? st oe ... , NOTES: 1978 sHANNON a WIL90!l 1990 WOODWARD-CLYDE CONSULTANTS 1981 WOODWARD-CLYDE COHSULTANTS 1982 WOODWARD-CLYDE CONSULTANTS I, BASE MAP FROM 1978 CORPS OF ENGINEERS I" • 2001 DAMSITE TOPOGRAPHY. 2. JOINT PLOT CONTOURS ARE THE PERCENT OF JOINTS PER I% OF AREA; CONTOUR INTERVAL OF 1,2, AND 3% O~~~~~O~Oiiiiiim:il200 FEET SC.t.L,t t ALASKA POWER AUTHORITY __ SUSITNA HYDROELECTRIC PRo,_J--EC~T::-----i WATANA DAM AND RESERVOIR <:nli\OO!<lil•I3!R~ RIGHT ABUTMENT GEOLOGIC MAP ., SOiltllo:AJQ~1 Vl~fti"t AI~MO~-------,== -..,------1 ANCHORAGE. ALASKA •• ,. JULI 1984 -, ........ ~EXHIBIT 14 NE ··~ .. 2300 ~ 2200 "" :u 2100 ; 2000 I 1900 I j:: w w 1800 ,!: z· R 0 ;:: < > 1700 w .... Ill! I' 1800 1500 1400 1300 T.O. 955.T FT. -~ / I I i r l I t ; l .__SHEAR '--fRACTURE ZONE · ·A~TERATJON ~~A~ TERATION "'-FRACTURE ZONE ·-·SHEAR -SHEAR ~I DH-11 (PROJ. ~0 Hl '· ·-ALTERATION ·-·SL. TO MOO ALTERED -FRACTURE ZONE MASSIVE DIORITE: rPOWERHOUS~ FOUNDATION LEVEL EL. !138Q f L_ GEOLOGIC SECTION C-C sw 2300 2200 2100 2000 1900 1600 1700 1600 1500 1400 1300 j: w w ,!: z 0 ~ > w _, w LEGEND ROCK~ ~ ~ DIORITE SUITE; DIORITE ,QUAftTZ DIOIIITE, GftANDDIOftiTE ALTERED DIORITE;IIODEIIATELY TO dEVEIIEL'I' ALTEIIf:O MONZONITE TO GRANITE STRUCTURE: SHEAR ZONE,WIDTH I TO!! FEET CONTACTS: -·~ TOP OF BEDROCI< OTHER: -'!\J-GROUNDWATER TABLE WITH D.lTA POINT, ~UNE/JULY 19B4 -si£AII FEATURE LESS THAN 3 FEET WIDE ]-ALTEIIATIOH FEATURE GREATER THAN 3 FEET WIDE NOTES: <D ® ® ® @ ® SECTION LOCATIONS SHOWN Otf EXHIBIT 12. SURFACE PROFILE FROM t"•200'10POGRAPHIC MAP; CORPS OF ENGINEERS,I978. FOR DET/IILED BOREHOLE DESCRIPTIONS, SEE EXPLORATION LOGS IN APPENDIX A. FOR GROUNDWATER DATA SEE ~PPENOIX F. CHANGES It> LITHOLOGY ARE SI!OWN GRAPHICALLY FOR THICKNESSES GREATER THAN !! FEET. All BOREHOLES ARE PROJECTED. THE IDENTIFIED DISTANCE IS TO THE BOREHOLE COLLAR. THE NOTES FOR BH-3 AND DH-11 AilE MODIFIED FROM ACRES AMERICAN, 1981. 0~!!!!!!!!!!!!5SO;';;;;;;.:il00 FEET SCALE c:: ALASKA POWER AUTHORITY SUSITNA iiYormr•.ECTRIC f"10Jt:CT WATANA DAM AND RESERVOIR POWERHOUSE AREA GEOLOGIC SECTION C-C ~run·~ IUSIJN4~oalfl"'fi.JI'( .1,/;V•;rttc ~·· ANCHORAGe, ALAS JULY 1984 EXtuBIT 15 -....... 2100 ........ _ I --~I::.~!J~9~_JL .. 3 JULY 19B4'f ' 'l I 2000 I I 1900 .. I 1800 I !!"! ~ w w ~ z 0 1700 i= < > w .... Ill 1600 1500 1400 1300 -...._ ----._('r-OI10UND SURFACE ' -' "' / .,"1 j ' -DH84-2 DIORITE r . GROUND SU'I~ ACE fL. 2024.2 o,J • 14 7'0VERBURDEN TOP OF ROCK 14,7 FT. OI.)RtTE - - - - FnESH TO SLIGHTLY WEATHERED HARD MODERATELY STRONG £_L_O~!~.}~Ef!.! • .C~f:!:.! F~TUI'EO FRESH, HARD, STRONG LOCAL ALTERATION, FRACTURE ZONES AND SHEARS DIORITE-QTZ DIORITE· MINOR FELSITE INTRUSIONS LOCAL VARIATIONS lN FRACTURE FREOUENCY AND DEGREE OF ALTERATION ROCK MASS GENERALLY VERY HARD, MODERATELY FRACTURED,f.TRONG LEGEND: -~ El.. 1565 WATER LEVEL ~ 2 JULY 1984 DATE MEASL'AED INTERVAL Llla(;QN T VALl£ --2.0 l NOTES; '1 ROO/CORE RECOVERY SCALE 0 50 100 PERCF.Nl' cTOP OF ROCK IU FT -CORE RECOVERY ROO (ROCK QUALITY DESIOHATION) FRACTURE ZONE INTERVAL li:'fl-t--if--1-piEZOMETER INSTALLATION SP • STANO PIPE PIEZOMETER PP • PNEUMATIC PIEZOMETER ·--DIORITE,SEVERF.LY ALTERED, WEAK (In uctu ot 3.Q II. drilled Jonglh) 1. BOREHOLE IN POWERHOUSE AREA INCLINED 30'FROM VERTICAL 2. DESCRPTIVE TERMINOLOGY DEFINED IN APPENDIX A. COAELOOS 0 50 100 SCALE 1 ,11 ~FEET ALASKA POWER AUTHORITY susiTNA }lvcitoE~E£rRiC ~ r;_l.1o~.9.'r: WATANA DAM AND RESERVOIR POWERHOUSE AREA GRAPHIC LOG BOREHOLE OH84-2 .J.f.W.Ifll(; NO -·--·-·--.. EXHIBIT 16