The Eklutna Hydroelectric Project, Anchorage, Alaska

STOLEN FROM RICHARD D. REGP THE ALASKA EARTHQUAKE, MARCH 27, 1964: EFFECTS ON TRANSPORTATION, COMMUNICATIONS, AND UTILITIES

Effect of the Earthquake Of March 27,1964, on The Eklutna Hydroelectric Project, Anchorage, Alaska

By MALCOLM H. LOGAN

With a Section on TELEVISION EXAMINATION OF EARTHQUAKE DAMAGE TO UNDERGROUND COMMUNICATION AND ELECTRICAL SYSTEMS IN ANCHORAGE By LYNN R. BURTON

GEOLOGICAL SURVEY PROFESSIONAL PAPER 545-A UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY William T. Pecora, Director

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 35 cents (paper cover) THE ALASKA EARTHQUAKE SERIES The U.S. Geological Survey is publishing the results of its investigations of the Alaska earthquake of March 27, 1964, in a series of six professional papers. Professional Paper 545 describes the effects of the earthquake on transportation, communications, and utilities. Where needed to complete the record, reports by individuals from organizations other than the Geological Survey are included in the series. Thus, this description of the Eklutna Hydroelectric Project-a key part of south-central Alaska's power system-was requested from the U.S. Bureau of Reclamation; so, too, was the section on the use of television for investigating damaged underground utility lines. Additional chapters in Professional Paper 545 mill describe the effects of the earthquake on The Alaska Railroad and on highways, airports, utilities, and communications. Other professional papers describe the field investigations and reconstruction and the effects of the earthquake on communities, on regions, and on the hydrologic regimen.

CONTENTS

Page Page Abstract ------A1 Effects-Continued Television examination of earth- Introduction and acknov ledg- Penstock, surge tank, and quake damage to underground communication and electrical ments------anchor block ------Powerplant and associated systems in Anchorage, by Geologic setting------Lynn R. Burton ------The first 24 hours------structures------Introduction------__------Effects on individual features Tailrace------Underground systems------_ ------of the Eklutna project- .---..- Transmission lines-- Equipment ------Eklutna Dam --_------Substations------Procedure------Intake structure ------Other earthquake effects in the Damage to systems------Tunnel and gate shaft - - - - - area------Interpretation of data------

ILLUSTRATIONS

FIGURES

Page Page Page 1. Index map of the Eklutna 14. Photograph of Eklutna power- Photograph showing damaged Hydroelectric Project---- A2 plant before the earthquake- A15 pump in project office---- - A20 2. Topography and surface ge- 15. Photograph showing piling Typical section of tailrace ology of the project area- - 3 in the powerplant founda- channel------20 3. Schematic plan and profile of tion------26. Photograph showing cleaning- the Eklutna project- - -- - _ 4 16. Geologic section through up operation at outlet of 4. Map and section of damsite surge tank, penstock, and tailrace conduit------area showing explorato~ powerhouse------27. Plan, section, and chart giv- work----_------____ 17. Typical ground settlement ing summary of damage 5. Photograph of spillway gate resulting from the earth- to tailrace conduit ------structure------quake------__------28. Aerial photograph showing 6. Aerial photograph of intake 18. Plan view of powerplant locations of cracks near area showing network of giving measurements of the powerplant------cracks- - _ ------settlement and deflection- 29. Aerial photograph showing 7. Geologic section showing lo- 19. Photograph of machine-shop Eklutna Lake area------cation of earthquake dam- foundation, showing sep- 30. Photograph of truck-mounted age to intake structure- - - aration of backfill mate- television equipment being 8. Geologic section along the rial from concrete footing- loaded at Denver for its line of the pressure tunnel- 20. Photograph showing damaged flight to Anchorage------9. Photograph of debris depos- 20,000-kva transformer con- 31. Details of television probes- ited in Eklutna tunnel- _ _ duit and terminal box---- 32. Arrangement of television 10. Geologic section through gate 21. Photograph showing damaged equipment during exami- shaft - - - - _ - _ - - - - - _ - - - - _ - heating-sy stem piping in nation------11. Geologic sect~on through the floor of the automotivc 33. Topographv, surface geol- surge tank-_------repair shop __------ogy, and location of frac- 12. Section through surge tank, 22. Sketch map of major earth- tures in underground penstock, and anchor- quake cracks in power- communication and elec- block area------_--_- plant area------trical systems------13. Photograph showing earth 23. Photcgraph showing cracks 34. Axial view of breaks in the settlement over penstock in pavement of Eklutna ducts, as seen on the tele- anchor block------roadway------__- - - - vision monitor screen---- -

THE ALASKA EARTHQUAKE, MARCH 27,1964: EFFECTS ON TRANSPORTATION, COMMUNICATIONS, AND UTZLZTZES

EFFECT OF THE EARTHQUAKE OF MARCH 27, 1964, ON THE EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE, ALASKA

By Malcolm H. Logan, U.S. Bureau of Reclamation

ABSTRACT

The March 27, 1964, Aliasha eaa- ported from Eklutm Lake to lthe power- consolidated sediments and overburden quake and its a&&ed aftershocks plant at tidewa'ter on Knik Amd Cook which densified and subsided during the caulsed damage requiring sever'al million Inlet by an underwater intake con- earthquake. Structures built on bed- dollars worth of repair to the Ekluitna nected to a 4.46-mile tunnel penstork. rock experienced little or no damage. HydroelMc Project, 34 miles north- The primary damage caused by the Underground communimtion and elec- east of Anehomge. Eleotric mice earthquake was at the intake structure trical 'systems in Anchorage mere exam- 6nom the Eklutma powerplant was inter- in Eklutna hke. No damage to the ined with a small-diameter television rupted during the early phase of the power tunnel wzs observed. The pile- camera to lmte damaged areas requir- Mamh 27 eanthquake, but was restored supported powerplanit and appurtenant ing repair. Most of the damage was (iaixrm.1'btently)until May 9,1964, when strudures, Anchorage and Palmer sub- concentrated at or near valley slopes. the plant was cl& for inspection and stations, and the twnsrmi~ssionlines suf- Thw parts of the systems within the wpai~. fered minor damage. Most damage majar slide areas of the ciity were Water for Eklutm project is tram- occurred to facilities construoted on un- destroyed.

INTRODIJCTION AND ACKNOWLEDGMENTS

The Eklutna Hydroelectric The lake is 7 mi'la long and is fed Although this report does not Project is a 30,000-kw (kilomtt) by melt maker from Eklutna Gla- discuss earthquake-damage reha- power development designed and cier, 4 miles ajbove the lake, and by bilitation, the repair of facilities constructed by the Bumau of Rec- precipi'tation runoff from a 119- damaged by the great Alaska lamation, U.S. Department of the square-mile watershed. Water is earthquake of March 1964 was dif- Interior, Ito bring urgently needed transported from the lake by an ficult, hazardous, and cositly. electric power to the rapidly ex- underwater intake connected ,to a Transmission poles had to be set panding mekropol~itmarea at An- 4.46-mile tunnel and 'tunnel pen- on steep icy mountain slopes; chorage, Alaska. The project was bstwck through Goat Mountain to \~eakened precast-concrete con- constructed during lthe 4-year pe- 'the powerplant (figs. 1,2,3). The duits could be strengthened only riod 1951-55. The powerpht project is for power production by working under 40 feet of near- (fig. 1) is lmted 34 miles north- only. Transmission lines, operat- freezing \\-ater; and sand and eagt of Anchorage on the Glenn ing at 115 kv (kilovolts) and ter- gravel were mucked from 4.46 Highway and is supplied by water minating a* substation facilities, miles of 9-foot tunnel requiring fmEklutna Lake, about 10 miles extend noPth to Palmer and south access by means of a 220-foot by road from the Glenn Highway. to Anchorage from the plant. vertical ladder. Al A2 ALASKA EARTHQUAKE, MARCH 27, 1964

CANADA

1000 MILES

1.-Index map of the Eklutna Hydroelectric Project. EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE

EXPLANATION I I I - ./ FLOOD PLAIN 1$:::.:.

Glacial till

Graywacke containing argillite inclusions

Greenish-gray metagraywacke

Thin-bedded argillite and some thin beds of graywacke

Contact

-,-I--75 Fault, approximately located Showing dip of fault plane

73 _L Strike --and- dip of beds Shattered zone o33 Drill hole

10 Test pit

700u 0 700 2100 FEET CONTOUR INTERVAL 500 FEET

2.-Topography and ourfare geology of the project area. ALASKA EARTHQUAICE, MARCH 2 7, 19 64

' diameter gate shaft 115-kv transmission

H igh-water line

PLAN

3.-Schematic plan and profile of the Eklutna project.

The decisions, actions, and im- of flow of electric energy. Juneau, Alaska, to W. Williams, provisions of Alaskan personnel This report was prepared in the project superintendent, Anchor- during the emergency and subse- Enginwring Geology Division of age, Alaska, and to their staffs quest repair operation have since the Chief Engineer's Office, U.S. ~vhose \vritten contributions, proven to have been in the best in- Bureau of Reclamation, Denver, photographs, and assistance dur- terest of communities in an area Colo. Acknowledgment is made ing the investigation formed the grown to depend on the continuity to G. N. Pierce, distriot manager, basis of this work.

GEOLOGIC SETTING

Cook Inlet is an elongated inter- Goat Mountain, a prominent local In places, glacial and more recent montane structural basin that feature of )the Chugnch Range, streams have reworked the 'till, so trends northeast-southwest be- rises abruptly from the southeast- it is sorted and somewhat bedded. tween the Chigmit and Talkeetna ern flank of the Knik Arm low- In some areas, nearly pure silt and Mountains on the north and the lands and forms a divide between clay are interstratified with coarser Kenai and Chugach Mountains on the Knik River and Eklutna River material. I11 the stream channels the south. Knik Arm, a north- drainages. and flood plain of the Ihik River, easterly extension of Cook Inlet, The Knik and Eklutna Rivers well-rounded gravel and clean occupies a lowland that is char- are in old glacial valleys, and hence sand predominate. acterized by glacial and al- the overburden consists of glacial Very little well-rounded gravel luvial sediments. braided streams, till containing material ranging in occurs along Eklutna River-the marshy areas, and broad tidal flats. size from large boulders to clay. stream which drains Eklutna Lake. EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE A5

The present stream channel is nar- The mountain through which densification of unconsolidated row and the steep banks have been the tunnel is driven is composed sediments and overburden. Myr- cut through a succession of sand, of a series of graywacke, argillite, iad cracks, ranging from a frac- clay, silt, and "dirty" gravel beds. and slate, all metamorphosed to tion of an inch to several feet in All this material is partly re- varying degrees (fig. 2). The width, were formed in areas un- worked glacial till. Where the rocks in the graymacke-slate- derlain by the unconsolidated velocity of the pr~ntstream is argillite series on the north slope sediments. Near bedrock out- slow, rounded gravel is found but have been extremely metamor- crops, a linear pattern of cracks its extent is not great. Shingle phased and crushed; bedding formed which, in general, paral- gravel mantles the ground surface planes are indistinct, and the rocks leled the bedrock configuration. in the vicinity of the dam. are highly weathered along the in- As distance from bedrock and Several terrace remnants, repre- tricate fractures and are jointed, depth of overburden increased, the senting old glacial lakeshores, are in several places the rocks are ser- linear pattern graded into a blocky present at higher altitudes along pentinized and slickensided. On pattern having the general ap- the south slope the rocks are the Eklutna River valley. Drill pearance of magnified mud cracks. poorly exposed. The bedding All cracking observed on the Ek- holes through the glacial till on planes are recognizable but vary this shore revealed varying depths in aktitude within short distances. lutna project was caused by ten- to bedrock. In the floor of the The higher peaks are composed of sional failure resulting from valley, bedrock is estimated to be dark-greenish-gray graywacke. densification of saturated alluvial several hundred feet below the The most obvious factor con- sediments. No failures were ob- surface; elsewhere it is closer to tributing to the destruction of the served where structures mere built the surface. Eklutna project facilities was the on bedrock.

THE FIRST 24 HOURS

When the earthquake occurred, amination, was started and station gized through a bus tie switch at at 5: 36 p.m. (Alaska standard service was restored at 5:55 p.m. 10: 10 p.m. The 115-kv Palmer time) on March 27, 1964, the pow- A wood-pole transmission line line, which had been damaged by erplant was operating at near structure on the 115-kv Palmer the slide, mas isolated mt the power- maximum capacity (31,000 kw) , line had been oarried away by snow plant. Service was first restored and the power system ~vasinter- slides. Two adjacent spans of to the Matanuska Electric Associa- connected through the Anchorage, transmission line, totalling 7,500 tion at Reed substation at 10: 43 Reed, and Palmer substations. feet, were destroyed. p.m., Marc11 27, after completion Major damage was sustained by Radio communication was tem- of system repairs. Service msre- two 115-kv air circuit breakers porarily interrupted btween the stored to the Palmer substa t' on and bushing-type circuit trans- Anchorage substation land the about 10 :00 a.m. on March 28 after formers serving the Anchorage powerplant. Damage at the An- completion of system repairs. and Palmer lines, but there mas chorage substation wnsisted of At 12: 12 a.m., March 28, both no visible indication of damage to fractured porcelain on all three generating units at Eklutna w~e either generating unit. The 115-kv lightning arresters. All off the line when the normal pen- two 20,000-kva (kilovolt-ampere) transformers shifted on their bases, stock pressure dropped apprecia- power transformers had shifted but, although )the 115-kv bus work bly. At 12 :40 a.m., penstock pres- on their rails and had subsided was distorted and severe strain sure restored itself and Unit 2 was several inches, as had the Camp placed on several bushings, 'there put back on the line. A11 exami- line transformer. A11 bushings were no failures. Indicating and n~ationof the inbake area showed and connecting busses were intact, alarm circuits had conduit damage, that the headgste was Still in full although under abnormal me- but all circuits remained operable. open position bdt \vas accepting chanical strain. The generator, A 'temporary bypass was installed, only a very small flow of water. which had been stopped for ex- and the Anchorage line was ener- There was no apparent damago A6 ALASKA EARTHQUAKE, MARCH 27, 1964 although shattered and upturned energized and an aerial patrol of areal subsidence disrupted cooling- ice on the lake indicated that there all lines and the lake wa~made. water facilities. Structural dam- had been considerable disturbance At 2 : 40 p.m., March 28, a shear age also occurred to the power- in the lakebed and shoreline. At, pin was lost on the Unit 1 wicket- plant building and boilers. The approximately 1: 30 a.m., low pen- gate drive, and thus began the first Chugacl~Electric Association Coo- stock pressure again caused a com- of a lfong series of shutdowns to per Lake plant was isolated by ex- plete plant outage. At 3 : 55 a.m., remove rock and other debris from tensive damage to its 115-kv pressure began to return to normal, the gaks and scrollms~. transmission line, and widespread so one unit was lagain started and During this period, other util- damage in the Anchorage area pro- station service and the camp load ities in the area were also having duced many distribution-system was picked up. At aboult 8: 00 problems. In the city of Anchor- faults which had to be located, then a.m., the penstock pressure s'tarted age, two 15,000-kv gas turbines either repaired or isolated. The dropping again, then suddenly were inoperable because of broken power-generating facilities at El- surged to above normal before lev- gas mains and ruptured oil tanks. mendorf Air Force Base and Fort eling off. A considerable amount The Chugach Electric Association Richardson were partly crippled of debris was noted in the tailrace. Knik Arm steamplant lost coal- by the loss of cooling-water The Anchorage line was again and ash-handling facilities, and facilities.

EFFECTS ON INDIIVID~UALFEATURES OF THE EKLUTNA PROJECT

EKLUTNA DAM On the upstream slope of the dam, gate structure (fig. 5) began to sub- the riprap is underlain by a sand side into the underlying void. The dam is an enlargement of a and gravel blanket 12 inches thick. This movement did not take place natural dam formed by a receding The dam has a height of 26 feet to any noticeable extent until early alpine glacier. As indicated in above the foundation, a length of in July 1964. At this time, two figure 4, the site was thoroughly 555 feet, and a volume of 5,000 cracks approximately 1 inch wide explored by means of drill holes, cubic yards. formed-one in the base of the test pits, and geologic mapping. An uncontrolled overflow spill- spillway slab and one in the sill of The reservoir, which is an enlarge- way having a crest altitude of 867.5 the gate structure. In addition, a ment of Eklutna Lake, is about 10 feet and a length of 150 feet is lo- large part of the spillway base slab miles southeast of the powerplant. cated onlthe right abutment. Lake had been #deprived of foundation The lake has a surface area of level at the time of the earthquake support by the densification that 3,247 acres, a length of 7 miles, was approximately 20 feet below caused the void. The gate struc- and a capacity of 182,000 acre-feet the spillway gate sill. ture was then declared unsafe for at mlaximum water surface alti- Early inspections of the dam impounding water. All gates tude of 867.5 feet. after the earthquake revealed no were locked open, pending recon- Construction of Eklutna Dam apparent damage. Immediately struction of the dam. after the quake, no cracks or other was completed by private interests evidence of quake-induced move- INTAKE STRUCTURE in 1929. In 1943 it was purchased ment were found in the vicinity of Diversion from EMutna Lake is by the city of Anchorage from the dam and spillway. The frozen made through an inlet channel, 100 which the Federal Government ground near the surface probably feet wide and about 500 fe& long, purchased it at the 'time the Bu- moved as a mass during the quake. excavated in the lake bottom about reau's Eklutna project was built. L a t e r observations, however, 60 feet below lake-surface altikude The dam was raised to a crest alti- showed that the alluvium beneath (fig. 3). The intake structure ex- tude of 875 feet above sea level. the frozen layer had densified and tends from this inlat channel for The upstream and downstream created a void. As thawing pro- 133 feet 8 inches. slopes of the dam and other areas gressed, therefore, the upper layers The intake structure hlas an ini- have been covered with riprap. of alluvium under the spillway tial trashrack, 112 feet long, built EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE A7

0 0 0 0 0 0. 9 9 9 4 2 -I d m tn EXPLANATION TYPE OF DEPOSITS 06 U.S. Geological Survey Churn-drill hole (4 in ) -1

.3 Alluv~um Test pit (6 ft x 7 ft) (,I10 m Drill hole (8 -to 3 -in. casing)

0 Bulldozer pit 0Till X Bench mark * Water table A-A Several perched tables Proposed dam axls noted dunw drsllzng

sand Lenses1

0 100 200 300FEET LilII I I

4.-Map and Section of damsite area showing exploratory work.

5.-Spillway gate structure. ALASKA EARTHQUAKE, MARCH 2 7, 19 64

Eklutna Lake

6.-View of Eklutna intake area, showing intricate network of cracks caused by the earthquake along the shore of the lake. of rectangular precast-concrete the structure and bo obtain samples The trashrack? transition, bulk- ssctilons. Each swtion is 26 feet of the gllacial flour and till on the head, and conduit seotions back of 8 inches wide and 37 feet long. lake bottom for stability studies. station 194- 06 in the bottom of Immediately do\mstream from the Two types of glacial materials, Eklutna Lake sustained the major trashrack structure is a precast- designated A and B, were found damage from the earthquake. wncre'te transition secti'on, 14 feet in the intake structure area. (Station numbers start at the in- 2 inches long. The inside of this These materials were classified pri- take and increase in the direction transition seation t,apers from a of water flow.) marily by their compaction and re- rectangular reinforced-concrete Earthquake-induced densifica- section 9 feet by 22 feet 8 inches to lated construcition clla~r;tcteristics tion of materials in Eklutna Lake a circular section 9 fee't in diam- rather than by composition : (fig. 6) caused the intake structure eter. At the end of the square-ho- Material A.-Owing to the in- to move approximately 44 inches round transition section is a bulk- stability of the material, the gla- toward the lake. Principal move- head seotion 7 feet 6 inches long. cial flour was excavated on a 20 to ment wm in a horizontal direction, Slots 'are provided in the bulkhead 1slope, and the lower part of mate- but was accompanied by a lesser section for either @topplanks or a rial A as exaavahd on a 10 to 1 amount of vertical displacement. fabricated bulkhead to be used in slope. A thin l~ayerof sandy clay Tensional forces produced by the event of (an emergency or for containing many boulders as much the horizontal shift caused separa- inspection purposes. as 3 fedt in diameter underlies the tion along joinbs in the precast Prom the end of the bulkhead glacial flour and overlies a loosely conduit, as shown in figure 7. section 'the water is conveyed to compacted glacial till. Ullconsolidated sediments, rang- the ent~anceof Eklutna tunnel Material R.-Fmm the top of ing in size from fine sand to through a 9-foot (inside-diamder) the B glacial-till contiact to the bd- cobbles the size of a football, funneled through these ruptures. precast-concrete pipe 225 feet long. kom of the inlet chlannel, the mate- An elliptical cone-shaped deprss- The wall of the pipe is 12 inches rial had to be blasted prior to sion, approximately 40 feet in thick. The pipe was cast in 16- dredging. Ifts clay content and maximum dimension, formed at foot sections, em11 section weigh- impermeability caused %he mate- the edge of Eklu'tna Lake over the ing about 40 tons. rial to be very compact in place conduit alinement near station Numerous holes were drilled in and even to settle back as a wm- 18 + 55, and numerous cracks were the general area of 'the tunnel 5n- pact mass on the lake hthafter present dong the lakeshore on take to selecrt the best location for blasting. either side of the oonduit. EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE A9

19+W PRECAST CONDUIT

JOINT SEPARATIONS. OFFSET. JOINT SEPARATIONS, OFFSET. IN INCHES IN INCHES IN INCHES IN INCHES A 0 LO 20 30 FEFl w HORIZONTAL AN0 VERTICAL

FLOW 10 3% 3% 2 2% 3 3 1% 1 1% 1% 3 3% 1% 1% 1% 1% 12 1% 1% 2 1%

c 5 2% 1% w In 13 2% 2% 1% 1% ALTITUDE AT JOINT SECTION A-A' 10 10 10 14 % 1% 1%

7 6% 6% 8 4% 15 2% 2% 1%

PRECAST CONDUIT 8 3% 3 3%

7.-Geologic section showing location of earthquake damage to intake structure. Rupturing of joints in the precast conduit occurred at the nmnbered locations. Amount and direction of l~lovenlentis shown in the table. Failure on or within the bedding material, induced by the earthquake, is believed to have caused the damage to the intake structure. No earthquake damage in the glacial till foundation was detected.

TUNNEL AND GATE SHAFT wheel gate that is used both for per minute. From station 25 + 82 A circular concrete-lined pres- emergency closure of the tunnel in to station 198 + 00 the rock is most- sure t~uinel,9 feet in inside diam- case the penstocks below or the ly interbedded argillite and gray- eter ancl 23,550 feet loiig (4.46 turbine in tlie powerplant are dam- wacke. The bedding planes are miles), conr-eys water froin tlle in- aged and for del~ateringthe pen- closely spaced and are recognizable take structure to tlie penstocks stock for illspection and mainte- but erratic. Much of the rock is leading to the po\verplant. The nance. intensely fractured, and iimumer- ca~acityof tlle t~ulnelis 640 sec- A tunilel adit is located at the able minor fault plailes and slip- ond-feet at a velocity of 10.06 feet outlet end of the tuililel near the page planes cut through the rock per secoilcl. The slope of the in- surge tank. The adit, which is at various angles to the tunnel axis. vert is 0.00341. ,\ 9-foot-diam- virtually the same diameter as tlhe From station 198+00 to station eter gate shaft, bet\\-eel1 invert main tunnel aiid is approximately 234f75 the rock is a metamor- altitude 790.76 aild 1,012 feet, is 300 feet long, provides one means phosed greenish-gray graymacke. located at station 27+25 so that of access to the tunnel for inspec- From statioil234 + 75 downstream, the tunnel may be dell-atered. tion and maintenance. It also the rock is uniformly fractured The t~tnnelternliildes at :I surge acts as n free-flow conduit for graymacke contaiiliiig irregular in- tank iiistallecl directly over the draining the tuiiiiel \\-hen eiltraiice clusions of nrgillite. During con- t~uinel 22,805 feet do~~*nstreain into the tunnel is necessary. The struction, ground ~vater flowed fro111 the bulkhead gate shaft. access door from the adit to the from most of the open joints. The surge tank, of the restricted- ttunel is watertight. Water also flowed through many orifice type, has an inside diameter From station 20+00 to station fault-gouge seams, which range in of 30 feet and a concrete-wall 25+32 (fig. 8) the material con- thickness from a fraction of an thickness of 18 inches, it extends sists of B-type glacial till. The inch to several feet and dissect the 176 feet vertically above the tun- sand layers coii~aiiisome ground rock at varying angles. nel. A 4%-foot rectangular sep- water, ~vllichhas a maximum total Approximately 2,000 cubic yards aration serves as a slot for the fixed flow of approximately 300 gallons of material was deposited along the ALASKA EARTHQUAKE, MARCH 2 7, 1964

Dri"y/yk D,,qng

H H WATER CONDITIONS AT TIME TUNNEL WAS DRIVEN

SEA L 5 ,b AXIS OF TUNNEL BEARING N. 10'52'45'' W. SLOPE=0.00341- - NO SUDDOrtS t-- LEVEL None-rock section +iHHHIH HHHI H H Cin. H-beams or lighter on centers more than 4 ft H Light support- H l H l lHHl HlHl -I uHHHy I Heavy support - H H H H 5-in. H-beams or heavier on centers 4 ft or less TUNNEL SUPPORTS 20 ft Roof overbreak T T Roof of tunnel n

40'F Rock 40" F40'F. 41' F. 12' F. 43.5' F. 44- F. 44.5" F. 45' F. 46' F. 46.5' F 47.5' F 48' F. 50' F. temperature Steel relnforcernent ///w/M&I///A 0 kzm g8 0 0 Type 1 Type 2 F+ o+ + 2s Y) 5 EXPLANATION

Glacial till Steeply dipping inter- Fault trace Strike and dip of beddedgraywackeand Showingdirectionof bedding planes argillite movement (In plan view) EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE

8000-10.W gallon

- 2-ftgouge seam (Station 208+75). \ - In this location supports are shown as 6-in., 20-lb. "H" Beam horseshoes on 2-ft centers but closer under Point of maxi- - mum cave height (Station 208+35). Here there are 10 Sets - between Station 208+30 and Station 208-l-40 - -

0ve tunnel invert at alt 747e'

1SEA LEVEL

f r E + 3 a i0 1: r\ mi ----- tag-ti ei== .-E gp *E a=$2: 0 s l 35 r

NOTE: Bedding symbols are averages of bedding planes in areas indicated. Bedding dip and strike symbols are 0 600 1200 1800 2400 averages in areas indicated and are ploned in plan view FEET with tunnel line bearing N. 10°52'45" W. - All geology on this summary sheet is from tunnel logs rather than projections from the surface

8 (above and left).-Geologic section along the line of the pressure tunnel. A12 ALASKA EARTHQUAKE, MARCH 27, 19 64

6" H-rlngs 5' outslde circumference Entlre shaft lagged wlth 2" x 12" t~mbers

Orlglnal ground DH 43 Alt 1032 4' lone

9.-Debris in Eklutna tunnel, typical of that deposited throughout the initial 3% miles of tunnel as a result of the earthquake.

tunnel invert. The debris consisted predominantly of rock fragments 1 inch in diameter, but ranged in size from sand to an occasional fragment 14 inches across. The debris (fig. 9) ~vas 12-18 inches deep and was uniformly dis- tributed from the gate shaft at station 274-25 to near Station 103+ 00. From statioii 103f00 to sta- 'tion 235 i-00, debris mas deposited in gravel bars of varying depths. The last mile of tunlie1 was relatively free of material. No structural damage to the tunnel was found. As part of the plan to design an ea~thquake-resistantstn~cture, the 42' N gate shaft at station 27t25 \\--as 780 I I 1 I I 26+65 26C85 27+0 5 27+45 27+65 27+85 28+05 founded in competent rock (figs. 8, STATIONS / Water sump 10) ; it mas reinforced to witlistand 15' x 15' x 20' internal bursting pressures. Hori- zontal joints in the shaft, indi-

cated by dashed lines on figure 10, 0 20 40 FEET II,,, I helped compensate for any possi- HORIZONT4L AND VERTICAL ble vertical deflections during an 10.-Geologic section through gate shaft. earthquake. No damage- to this structure was discernible. EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE

PENSTOCK, SURGE TANK, AND ANCHOR BLOCK

The power penstock conveys water from the surge tank at the end of the Eklutna tunnel to the pow- orplant turbines. Tlie penlstock is about 1,088 feet long, is installed in 30-foot sections, and is a t-arilable- diameter (91-, 83-, and 75-inch out- side diameter) welded and coupled steel pipe encased i11 concrete. Plate 'thickness of the pelistack varies froin KG inch at t11e initial section to 1%inclies at the terminal section. In profile, the penstock roughly parallels the mountain- side, descending for approxi- inately 864 feet at an angle of 58" ; it the11 levels off and oontinues througl~a liorizontal section about 501 feet in length. At the powver- plant the penstock bifurcates into two 51-inch-diameter 23-fooit-long branches which are connected 'to the spiral cases of the tu~bines. The penstock tunnel was excavated in weathered rock, except at the lower end where the tunnel section emerges into overburden material (figs. ll, 12). In order to traverse this overburden material, wl~iclilay between tAllerock-tunnel 11.-Geologic section through surge tank. section and the pile-supported penstock anchor, a special tunnel section had to be designed and built. A maximum residual separation penstock was filled with tunnel In effeot, this reach of tunnel was of one-sixteenth to one-eighth inch leakage water. After the penstock designed as n length of conduit was measured in the penstock ports was filled,)the leakage was diverted suppoted a't one end by the tunnel of the powerhouse wall. The en- out through the adit-tunnel door rock and at the other end by a pile- tire penEftock from the tunnel to and a two-man liferat%was floated supported bent. the unita appeared to have sus- down the penstock. The desired The penstock, surge tank, pile- tained no permanent deformation. rate of descent of the raft was con- Fine line cracks in the overlapped supported anchor )black,and pow- trolled by releasing the water from painted surfaces at bhe coupled erliow evidently oscillated as rtn the penstock through 'the butterfly sleeve joints did, however, indicate integml unit during the earth- unusual pipe vibration. valves, wicket gabs, land drain quake. Very libtle relative move- In order .Do examine the interior lines. Indtruotions to obtain the ment occurred between these fea- of the penstock, an unusual method desired water discharge were re- tures although backfill in the an- of descending through this 6-fodt- layed from the raft to the plant by chor-block area subsided (fig. 13). dirtmeter pipe was devised. The radio and telephone. A14 ALASKA EARTHQUAKE, MARCH 2 7, 1964

EXPLANATION GrStat~on254+90 (high-level surge tank) Start of penstock (hlgh level) Statlon 255+14 50 1 TOPSOIIand pebbles, cobbles 10 Graywacke and argillite. Quartz- //Statton 255+30 (low-level surge tank) and calcite-filled fractures. 2 Weathered rock, greentsh-gray Very broken, brecciated, some 3 Graywacke and argiliite, dark-gray crushed core, sllckensides. to black: distorted. Quartz- and small intrusions; contorted calclte-ftiled joints and fractures. 11 Topsoil Slickensides. Iron-stained. Some open joints 12 Clay, sandy, Gravel and boulders 4 MOSS.topsoil 13 Graywacke. argillite. and epilitic 5 Sand. silt, gravel. boulders basalt. Broken, crushed and brecclated. Contorted. Granite 6 Siliceous graywacke. argiliite and intrusions. Quartz and calcite metasiltstone. Badly broken. Stringers shattered, brecclated. Iron- stained weathered fractures. 14 Organic material Quartz- and calctte-filled joints 15 Clay. silty. plastic and fractures and open jolnts 16 Sand. boulders, rock fragments 7 Clay. sandy. silty 17 Rock fragments 8 Weathered rock, granular, brownish-gray 18 Graywacke and argilllte, broken 9 Graywacke, hne-gratned; contains and weathered intrusions of brown felsttic ma- 19 Rock fragments. broken. crushed, terial brecclated, serpentlnlzed

LL 500 - z

12 (above).-Section through surge tank, penstock, and anchor-block area, showing drill-hole data.

13 (left) .-Earth settlement over the penstock anchor block directly behind the powerhouse. This settlement did not appear until 2 weeks after the earthquake. Presumably, the bridging effect of the blacktop and ground frost concealed the settlement during this period. - EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE A15 POWERPLANT AND ASSOCIATED STRUCTURES The powerplank (fig. 14) is di- vided into four main stmctures : the power'house containing the generating units and accessories, the machine shop, the transformer structure, and the switchyard. Surrounding the powerplant is a yard area containing an automotive repair shop, warehouse, and office building. The powerhouse is a reinforced- concrete structure 71 feet long and 80 feet 8 inches wide. Because of the relatively unstable foundatioil conditions and the high earthquake potential, the design included pile foundat,ions for the powerhouse, machine shop, trans- 14.-Eklutna powerplant before the earthquake. former strnctnre, and penstock anchor block. The foundation included 289 I-ertical and 110 bat- tered 14-inch, 73-pound, H-section piles (fig. 15) and \\*asdesigned to withstand an earthquake factor of 0.15 gravity and an acceleration of the foundation of 4.8 feet per sex- ond per second. A11 average pile penetration of 5.0 feet into bedrock was achieved. Foundation material between the piles consisted of in-place water-bearing river sand and gravel. Adjacent to the west wall of the powerllouse is a pile-supported machine shop 78 feet long, 27 feet wide, and 20 feet high. The su- perstructure of the machine shop has structural-steel framing and reinforced-concrete walls 10 inches thick. The structure is pinned to 15.-Some of the piling in the powerplant foundation during construction. Piles in piles througll concrete pile caps. lower foreground and along left slide have been cut off to grade prior to capping. The main power transformers that step up the generator lorn protect the transformers from The switching equipment for voltage are located in the pile- snow and rock slides. Firewalls the powerplant is located on three supported transformer structure separate the transformers and levels. The switchyard equip- adjacent to and southwest of the serve as foundations for the take- ment itself-consisting of the powerhouse at altitude 41.25 feet. off structures that carry the pow- power circuit breakers, disconneot- Protective walls were placed on erlines to the switchyard on the ing switches, and busses-is the south side of the structure to powerhouse roof. on the roof of %hepowerplant at A 1.6 ALASKA EARTHQUAKE, MARCH 27, 1964

h + 2 '5 c a .P m 6i NOTE: In DH 92, 65.5 ft east of centerline. fault material from altitude -27.4 to bottom of hole at altitude -87.6, indicates that fault zone increases in thickness and altitude to the east. Gouge layers within 1000 the fault zone vary in thickness from 1/2 to about 4 in. Drill core extremely difficult to recover. Ap- proximate dip and strike -N 87" E-16' N. Fault W material is consolidated material except in the lL narrow seams. The rock is recemented fault breccia f 900 and is fairly sound in place. When excessive water pressure is used indrilling, rock breaks into small 0 particles I/. to % in. It can be cored with diamond -

500 - Graywacke and argillite - 700 IIIIII 0 0 L 8 8 0 k! 400 - 5, 7 Lo3 LD 8 f ui - CONTINUATION OF PROFILE n 3 FROM POINT H '- 300 - 3 -

200 - -

100 -

0 -

- Graywacke and

loo 0 0 0 0 0 0 0 0 0 0 o+ 8 + 8 8 ? Y 7 0 ? 0+ 0 2 m 0 d Lo h 01 rn rn % w 2 w 0 w w 2 w F w N N N N N N N N N % 2 N r. N

16.-Generalized geologic section through surge tank,penstock, and powerhouse. altitude 92.50. The main power penetration resistance holes made conduit were excavated in water- transformers that step up the gen- to evaluate the bearing capaci,ty of bearing river sand and gravel, and erator low voltage are located in the overburden material under the the area had to be pumped during the transformer bay at altitude powerhouse foundation. A gener- excavation. Some sloughing of the 41.25. The high-voltage bushings alized geologic section is shown in backslope in the noritheast corner of these main power transformers figure 16. of the excavation occurred during are connected to the main switch- The upper 10-12 feet of the sec- the extreme high-water period of ing equipment locater? Dn the roof tion consists of organic, slightly the Lake Gwrge breakup. at altitude 92.50. The 115-kv bus plast,ic sil,t containing occasional Interstratified discontinuous lay- structure on the powerplant roof angular graywacke fragments. ers of stream gravel, sand, silt, and oonsists of two bays to supply the Below the silt a layer of talus 5-8 clay underlie the talus and overlie 115-kv lines to the cities of Palmer feet thick, containing angular the weathered bedrock surface. A and Anchorage. graywacke boulders in dark- flood plain extends north and w&t About 30 holes were drilled in brownish-gray organic sandy clay, from the powerplant site for sev- the powerplant area during the ex- lensed out downstream from the eral miles. The drainages from ploratory and early construction powerhouse foundation. The base both the Knik and Matanuska stages. Nineteen of these were of the powerhouse and the tailrace Rivers spasmodically aggrade, EFFECTS ON EKLUTNA FIYDROELECTRIC PROJECT, ANCHORAGE A17

degrade, and change their channels throughout the spring, sum- mer, and fall seasons. These erratic sedimentation phases ac- count for the interstratified sedi- I ments in the powerplant area. 1 Talus from the adjacent hillside I extends a short distance from the toe of the slope. The talus is I I generally overlain by slightly plas- ) tic organic silt recently deposited during the annual flood stage of the Lake George breakup. The water table beneath the power- I plant fluctuates with the Knik River and has a mean depth of 28 feet. The principal area of damage occurred between the powerhouse and machine shop along the 1-inch 17.-Typical ground settlement resulting from the earthquake. Settlement is near cork-filled expansion joint. The the northeast corner of the powerhouse at the location of the septic tank. two structures oscillated a%differ- ent intensities, and the intercon- I necting drainage and electrical 1 systems were sheared. The differ- 1 ential horizontal displacement be- '~rea around transformer / tween buildings was three-fourths structure has been graded. Extent of 1 of an inch, bu6 the vertical dis- settlement could not placement was negligible. Back- be measured IW Horlrontal movement fill around the entire periphery of (gravel surface and concrete) the plant and under the machine I POWERHOUSE 1 I shop settled erratically from a few I inches to a few feet (figs. 17-19). The fill in which these failures I Relative movement Yl.4 oocurrd is composed of well- i graded sand and gravel obtained from 'the Knik River. Most of the I gfiavel pa~t5cleswere subrounded lib I and were composed of a wide va- C------MACHINE SHOP ------4 riety of unweathered igneous, met- I NOTE: Numbers indlcate inches of relative amorphic, and sedimentary rocks. settlement as measured between earth O 20 40 FEET The sand ranged in ghape from surface (backfill) and concrete - I rounded to langular, a noticeable 18.-Measurements of settlement and deflection at the powerplant. percentage being elongated and flattened. The sand was eom~d bution in the gravel fraction of the A dragline and two bulldozers predominantly of slate grains. were used for phaeing and spread- Standard ing the backfill. The material was Silt-size particlles mere present in aieve Percent Percent wetted for proper compaction and small amounts, but tended to wasl~ size retained cumulative 6 in------0 0 consolidated by equipment travel. away during h~andling. The pit 3 in------2 2 Gasoline-powered immersion-type 1% rn------22 24 run material oonsisted of 35.1 per- vibrators and mechanical bampers cent sand and 64.9 percent gravel. 3/4 in ------36 60 % in ------27 87 were used in areas Snamssible to A weighted average of size distri- No. 4------13 100 the bulldozers. A18 ALASKA EARTHQUAKE, MARCH 27, 1964 Postearthquake examination showed that the drainage system leading into the floor sump was plugged with a mixture of fmely ground concrete and cork and the drainage line from the fanroom area was sheared. In addition, an aroma of fuel oil from several of the drains was quilte prevalent. Ground walter from the surrounding sedimenbs and fuel wil from s ruptured, buried bnk entered the drainage system through the sheared line. Within the transformer structure, the two 20,000-kva transformers moved from 3 'to 5 inches when tack-welded mil s6ops broke loose. Both transformers settled a few inches but not enough t~toverst~ess any of the bushings or bus connec- 19.-Machine-shop foundation showing the separation of backfill material from the tions. Although the bottom of the concrete footing. Approximately 1.5 feet of H-section pile is now exposed as a result of settlement caused by the earthquake. 120-volt terminal cdbinet (fig. 20) on one of 'the transformers broke open and the athhed conduits were pulled loose, the circu$.ts remained operative. The 750-kva cmp transformer settled nearly a foot, land the primary leads had to be lengthened to relieve the strain. The 115-kv switchyard on the roof of the powerplant was exten- sively damaged. Two single- phase air circuit breakers were damaged. Each phase consists of an air receiver, two hollow porcelain insulator columns, porcelain extinction chambers, arcing contacts, and a bushing-type current transformer. The hollow insulator columns are mounted at the ends of the air receiver and carry compressed air to, and provide support for, the extinction chambers and arcing contacts. The free- standing hollow insulator columns broke at the base and thus caused complete collapse of the contact 20.-The 20,000-kva transformer conduit and termlnal box damaged by movement of mecllanism. porcelain of tile cur- the transformer during the earthquake. Rail stops consisted of a %- by l-inch-wide bar tack-melded to the rail. The tack-wdds broke and allowed the transrfomer to rent transformer cracked and move on the rails. was lost. EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE A19

The ground beneath the north end of the wood-frame structure housing the automotive repair shop settled about 1 foot and moved approximably 10 inches horizontally along a tensional crack that destroyed the floor and the radiant heating sygtem in the floor slab (fig. 21). Lighting fixtures were torn loose from the wall. Prom a point west of the garage, cracks as much as a foot wide and several feet deep (figs. 22, 23) extended eastward adjacent to the north wall of the warehouse and crossed the roadway to the project office building. Cracks also extended from garage to the ZI.-Damage to the heating-system piping in the floor of the automotire repair shop southwest corner of the warehouse. caused by the earthquake. 7Surge tank IPenstock

0- 50 100 FEET 22.-Location or major earthquake cracks in the powerplant area. fl.20 ALASKA EARTHQUAKE, MARCH 27, 1964 A much larger crack occurred in State Highway 1 opposite the entrance to the project area. Backfilling the pavement cracks was a continuing operation for several weeks as adjustment- believed to have been caused by ground thaw along the cracks- continued to take place. Damage to the camp housing was not extensive. Chimneys were damaged, and two heating-oil tanks tipped over. The project office is a wood- frame structure with concrete floors. The concrete foundation and curb separated from the floor slab as much as 2 inches. The floor settled around the well casing, leaving the pump base approxi- 23.-Pavement damage caused by the earthquake. Cracks extend from the garage mately 5 inches above the floor (fig. east along the north wall of the warehouse (right of photograph) and thence acrm 24). Miscellaneous damage con- the road to the project office (left of photograph). sisted of overturned files and storage cabinets, cracked floors, damaged light fixtures, and broken joints in the chimney. The north wall of the structural- steal warehouse separated from the floor slab from 1 to 3 inches. Storage bins were tipped, and spare insulators were damaged. Foundations supporting the main structural members settled approximately an inch along the north side and a slight cracking

Pump t of the building resulted. The -- electrical service-drop attached to the roof pulled loose during the earthquake, and breaks in the asphalt roofing were caused by the flexing of the cold roofing paper.

TAILRACE Water from the draft tubs of %.-Pump in Eklutna project office showing the effect of the earthquake. Base of the turbines in the powerplant is pump is now approximately 5 inches above the floor. discharged through a 209-foot- long pressure tailrace conduit under the Glenn Highway to an open tailrace channel leading to the Knik River. The tailrace conduit is made up of rectangular reinforced-concrete 25.-mica1 section of tailrace channel. transition sections of varying EFFECTS ON EKLUTNA WDROELECTRIC PROJECT, ANCHORAGE A21 widths and depths. The terminal section of the conduit is 50 feet long and flares outward in the downstream direction from a width of 14 feet 6 inches to 46 feet 6 inches. This terminal section is also of varying depth and has five openings separated by 10-inch walls through which the water passes into the tailrace channel. Stoplog slots at the outlet of the conduit are used Ito dewater the conduit or to dewater both draft tubes at the same time. The banks of the open tailrace channel (fig. 25) are built on a 2 to 1 slope and are lined wit11 riprap at the junction wit11 the tailrace conduit. The channel has a top width of about 75 feet, a bot- 26.-Cleaning-up operation at the outlet of the tailrace conduit. Debris was de- tom width of 25 feet, and a depth posited following the rupture of the tunnel intake at Eklutna Lake during the of about 12 feet 6 inches. earthquake. The upper 4-6 feet of material utlderlying the tailrace is silt and sandy silt, which in turn is underlain by a 2-foot layer of sand and hegravel. Beneath the sand and fine grarel is sand and coarse gravel. During construction of the tailrace, some sloughing occurred in the sand and gravel layers during extreme high tides and when water was added to the cl~aimelby operation of the powerplant. Also, during the period of extremely high water at the time of the Lake George breakup, there was some sloughing of the banks. When the pow-erplant was shut down for repair of the intake (fig. 26), the 209-foot-long pressure tailrace conduit mas inspected and t- No apparent latera cleaned. About 110 cubic yards of rock and mud had been deposited in the conduit, presumably Approx~rnateground surface after the break in the precast pipe PLAN OF TAILRACE CONDUIT AI~40 0' )Crack in ceiling 28' asphalt highway section of the tunnel intake. The I L--J4 ABC D E ' Alt 19.5 j ' F inspection also revealed consider- I able shifting of the seations near- -Flow-+ est the powerplant (fig. 27). Regional subsidence raised the SECTION B-B high-tide water level approximately 3 feet. 27.-Summary of damage to tailrace conduit. pp --

ALASKA EARTHQUAHE, MARCH 2 7, 1 9 6 4

28.-Location of ground cracks in the vicinity of the powerplant. EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE A23

The ground surface was severely Matanuska Electric Association's on their bases. Primary bushings cracked (fig. 28) in the area ad- 34.5-kv line and the 12.47-kv were not damaged, but one second- jacent to, and parallel with, the Palmer area distribution system. ary bushing had sufficient stress 2,000-foot-long open canal section I11 order to carry the Palmer load on it to bend the transformer of the 'tailrace. The cracks through the limited capacity of cover. Conduits for the indicat- ranged in width from a few inches the Reed substation, auxiliary ing circuits on the phase C trans- to 5 feet and had the effect of cooling had to be provided by former were broken at the ground squeezing in the sides of the chan- truck-mounted fans. line, but the circuits remained nel. The invert was irregullarly operative. Sections of the rigid mantled by gravelly debris rang- SUBSTATIONS bus at the high-voltage bus were ing in depth from a few inches to The Anchorage substation is bent. The single-phase station several feet. situated on a terrace of glacial till service transformer shifted on its overlain by less than 1 foot of soil. base but was not damaged. The TRANSMISSION LINES Beneath this overburden and be- battery rack and radio equipment yond a depth of 8 feet, or below inside the substation building The 115-kv Anchorage line was foundation grade, the material shifted but were not damaged. not damaged, but the earthquake consists of a fairly uniform clayey The Palmer substation is in a triggered a sno\v and ice slide near sand and gravel. The water table heavily wooded arezz immediately the Knik River bridge that swept is 25 feet below ground surface. south of the town of Palmer. away a three-pole guyed structure, Lightning arresters on each of Foundation materials consisted of 7,500 feet of conductor cable, and the single-phase power transform- 0.8 feet of dark humus and topsoil, an access road on the Palmer line. ers at the substation were dam- 3.0 feet of dark-grayish-brown The transmission lines were re- aged. The arresters broke at their slightly sandy silt, and about a 1- paired on April 8, 1964, and serv- bases and dangled from the line. foot mixture of dark-gray silty ice was restored on April 16,1964, All three "stacks" of each arrester sand and poorly graded gravels after the air circuit breaker was were broken. One lightning ar- and cobbles. The depth to the repaired at the Eklutna switch- rester on the Chugach Electric water table \\-as not determined. yard. While the Palmer line was Association 16-mva (millivolt-am- The only evidence of damage at the out of service, power was deliv- pere) transformer was also dam- Palmer substation was an oil leak ered to the Palmer substation aged. All three transformers at at the base of a transformer from the Reed substation over the the Anchorage substation shifted bushing.

OTHER EARTHQUAKE EFFECTS IN THE AREA

There is evidence, though mea- The slides were composed of talus summarized as follo\vs : ger, indicating a general subsi- fragments held in an ice matrix, 1. No major slides were observed dence of the Eklutna powerplant but water was freely flowing be- along the Copper River main area, including Goat Mountain. neath them and no ponding was stem, although a slide was An exceptionally high tide was re- taking place. Earthquake effects present across Klutina River, a tributary of the Copper ported during the week of May 12- mere confined to alluvial deposits, River. No water was being 15,1964, but settlement of the gen- and conspicuous cracks were ob- impounded. eral area probably contributed to served in nearly all alluvial fans 2. Numerous sno\\-slides were seen the flooding. bordering Eklutna Lake. along the Matanuska River A helicopter reconnaissance of Aerial surveys were conducted valley. the Eklutna Lake drainage area to determine if major dlamage had 3. Some shiftring of 'the Lake (fig. 29) disclosed that earthquake occurred at potential project areas. George, Surprise, and Colum- slides had blocked three valleys. The results of these surveys clan be bia glacier icefield was noted. A24 ALASKA EARTHQUAKE, MARCH 2 7, 1964

29. Aerial photograph showing general area surrcr~~ndingEklutna Lake. 1

4. The U.S. Geological Survey Creek, liash\vitiza R i v e r , Hongkong Bend. The only assessed the earZllqualre ef- T a 1 k e e t n a River, Sheep new large-scale landsliding fects on pteatial dainsites in Creelr, Small Lnke near Ju- \\-as oil the Kashwitna =ver, the Anchorage-Semard area. neau Creek, Moose Horn but this slide did not affect These sites are on Nellie Juan Rapids, ICeilni River, Juneau consideration of B damsite Lake, Surprise Creek, Lost Creek, IZasilof River, and upstream. - .- EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE A25

TELEVISION EXAMINATION OF EARTHQUAKE DAMAGE TO UNDERGROUND COMMUNICATION AND ELECTRICAL SYSTEMS IN ANCHORAGE

BY LYNNR. BURTON,U.S. BURE~UOF RECLAMATION

I I INTRODUCTION asbestos-cement ducts, buried 4-6 and brush before the examination. feet beneath the streets and alleys That part of the communication As a result of the earthquake of the city. These ducts, contain- system extending from A Street to of March 27, 1964, the city of ing telephone and power cables, are E Street along the alley bet~ceen Anchorage experienced s e v e r e encased in concrete envelopes. Third and Fourth Avenues was de- damage to its underground utili- Manholes, spaced 180-540 feet stroyed by the Fourth Avenue ties systems in addition to the apart, provide access to the en- slide, and a section of the system great damage sustained by surface velopes. Each bank of ducts along Eighth Avenue west of L structures. Temporary repairs to includes at least one empty duct Street mas destroyed by the L these systems were made as that was used for the television ex- Street slide. quickly as possible after the earth- amination. 14i1y damage observed quake to permit resumption of in this duct was assumed to incti necessary services ~~-ithinthe city. EQUIPMENT calte damage to the entire envelope Permanent repairs were included at that location. In areas where The closed-circuit television in that phase of the Alaska Resto- the two systems are closely paral- equipment used was designed pri- ration Program administered by lel, only one system was examined. marily for examination of explor- the Corps of Engineers. The ducts mere cleaned by mandrel tutory drill holes 3 inches or more In order to avoid costly excavation of the buried communication and electrical systems to determine the specific locations requiring repair, the Corps of Engineers requested the use of a small-diameter closed-circuit television camera owned by the U.S. Bureau of Rec- lamation. This instrument, 2% inches in diameter, was the only television camera available which was small enough to pass through the cable ducts. The television equipment was flown from Denver, Colo., to Anchorage and back by the Military Air Transport Serr- ice (fig. 30). During September and early October 1964, 23,594 linear feet of cormnunication system and 10,510 feet of electrical system mere examined in the An- chorage business distriat and various residential areas by means of this equipment. UNDERGROUND SYSTEMS The ~mdergrouncl communication and electrical systems consist generally of banks of four to 30.-Truck-mounted television equipment being loaded at Denver for its flight to twelve 31h-inch-inside-diameter Anchorage, Alaska. ALASKA EARTHQUAKE, MARCH 27, 1964

Configuration for fishing tool Coaxial cable Upper terminal piece Ball bearings Expanding seal Lower end of terminal piece Vidicon camera Vidicon tube Focusing coils Focusing port Camera lens Illumination bulb Mirror Compass Viewing window Illumination bulb Resistance clinometer Slip ring Servomotor Moisture warning Silica gel

PROBES FOR:

Lateral Axial - viewing viewing

31.-Details of television probes. EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE

- Ground surface

3%-inch-diameter Concrete envelope

32.-Amngement of television equipment during examination.

in diameter to obtain various geo- PROCEDURE systems, locations of cracks ob- logic data. It also has numerous The television probe was drawn served during the examination, nongeologic applications. The through the ducts by a small-gage and approximata positions of the equipment is mounted on a truck wire rope attached to a pulling grabens formed at the heads of the and includes a control console and bridle on the probe and wound on L Street, Fourth Avenue, and monitoring unit, approximately a winching drum. The winching First Avenue slides are shown in 1,000 feet of coaxial cable, and two drum was coupled to an electric figure 33 (p. A28, A29). For aim- types of probes in which the mini- motor through a variable-speed plicity, the alinements of the two aturized television camera is in- transmission to permit variation in systems are combined and shown serted (fig. 31). All operating logging speed. Direct communi- as a single system. The direction switches and an 8-inch monitor or cation between the television and of movement, where it could be de- viewing screen are located at the winch operators by sound-powered termined, is indicated by small control console. The instrument telephone provided coordination arrows. operates on 110-volt 60-cycle alter- of viewing and logging speed, Cracks in ithe ducts were clearly nating current. An attempt was which was normally 10-12 feet per visible on the monitor screen, and made to use a lateral-viewing minute in undamaged ducts. The the amount of separation and off- probe in this examination, but its general arrangement of the various set was accurately determined. length (55 inches) prevented pas- components of equipment during Approximately 90 percent of the sage through many of the bends in operation is shown in figure 32. cracks exhibited no measurable the duct lines. The axial-viewing displacement and were not con- probe, which is only 30 inches long, DAMAGE TO SYSTEMS sidered indicative of serious dam- could be passed through all but the Topography and surface geol- age to the concrete envelopes. sharpest of the bends and was used ogy of the northern half of the Lateral, vertical, and longitudinal throughout the examination. city, alinement of the underground displacements along fractures were ALASKA EARTHQUAKE, MARCH 27, 1964

P 33.-Topography, surface geology, 'mdlocation of fractures EFFECTS ON EKLUTNA HYDROELECTRIC PROJECT, ANCHORAGE

EXPLANATION 0 500 1000 1500 FEET Qal Alluvium ...... Qs Swamp deposits Contact - Qaf A'1uvia1 fan deposits ---- Alinement of underground communication N QO' Outwash and electrical systems Qc Abandoned-channel -*+- deposits Location of cracks having discernible 1 Qpi Pitted outwash separation or offset. Arrow indicates apparent direction of movement Geology from Miller, R.D., and Dobrovolny, Qgi Glaciofluvial ice-con- YL-L- -. . . Ernest, 1959 (1960). Surf~cialgeology of , tact deposits Location of cracks having no discernible Anchorage and vicinity, Alaska: U.S.Geol. Qbc Bootlegger Cove Clay separation or offset Survey Bull. 1093, pl. 1

in underground communication and electrical systems. A30 ALASKA EARTHQUAKE, MARCH 27, 1964

%.-Axial views of breaks in )the ducts, as seen on onthe television monitor screen. observed at 52 locations. Photo- vicinity of the Fourth Avenue slide Movement mas to the north or graphs of two such fractures, as and in areas near the slopes of south at 13 of these locations. In viewed on the monitor screen, are stream valleys and local drainage general, these data suggest that the shown in figure 34. The maximum channels. The concentrations of north-south component of ground displacement noted was 1 inch, al- fractures north of Sixth Avenue motion was more severe than the though most were in the 1/1 6- to x- between Barrow and F Streets are east-west component and that the inch range. Soil and water had clearly the result of ground adjust- direction in which the induced entered the ducts through many ments related to the Fourth Ave- tensile forces acted was strongly such openings, and water was nue slide. Others, such as those influenced by the free faces repre- found in some areas where only located on Thirteenth Avenue and sented by Ship Creek valley to the hairline cracks were present. along C Street south of Thirteenth Avenue, probably refleot local sub- north, Chester Creek valley to the INTERPRETATION sidence resulting from incipient south, and the Cook Inlet bluffs to OF DATA failure of outwash and alluvial the west. Lack of a comparable materials on valley slopes. free face to the east may explain Although their plotted locations The direction of movement was the absence of serious damage to exhibik no well-defined pattern, the determined at 18 of the 52 loca- the underground systems in the cracks are conce~~tratedin the tions where displacement occurred. eastern part of the area.

U. S. GOVERNMENT PRINTING OFFICE : 1967 0 - 224-630