failure of baldwin hills reservoir 1963 interpretation of step by step failure sequence 1987...

8/16/2019 Failure of Baldwin Hills Reservoir 1963 Interpretation of Step by Step Failure Sequence 1987 Engineering Geology

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Engineer ing Geo logy ,

2 4 ( 1 9 8 7 ) 8 3 - - 8 8 8 3

E l s ev i e r S c i e n c e P u b l i s h e r s B .V . , A m s t e r d a m - - P r i n t e d in T h e N e t h e r l a n d s

F A I L U R E O F B A L D W I N H I L L S R E S E R V O I R 1 9 6 3 - - I N T E R P R E T A T I O N

O F S T E P- B Y -S T E P F A I L U R E S E Q U E N C E

T H O M A S M . L E P S

Consu l t ing Civi l Eng ineer, P .O . Box 2228 , Men lo Park , Cal if . 94026 U.S .A . )

( A c c e p t e d f o r p u b l i c a t i o n D e c e m b e r 1 9 8 6 )

I N T R O D U C T I O N

I n t h e 1 9 6 4 a n d 1 9 6 9 r e c o rd s o f o b s e r v a ti o n s m a d e o f e x p l o r a t o r y e x ca -

v a t i o n s in t o t h e n a t u r a l f o u n d a t i o n m a t e r ia l s u n d e r l y i n g t h e B a l d w i n H il ls

R e s e r v o i r li ni ng a n d u n d e r d r a i n s y s t e m , th e r e w e r e n o le ss t h a n 2 5 i n s t a n c e s

w h e r e o b s e r v e r s d e t e c t e d o p e n v o i d s p a ce s i n t h e f o u n d a t i o n . V a r i o u s p o i n t s

o f v i e w h a v e b e e n a d v a n c e d c o n c e r n i n g t h e o r ig i n o f t h e v o i d s o r c a v it ie s . It

is c l ea r, h o w e v e r , t h a t t h o s e v o i d s u n c o v e r e d w e r e n o t o f a si ng le t y p e , o r

s h a p e , a n d i t f o l l o w s t h a t n o s i n gl e m e c h a n i s m w a s r e s p o n s i b l e f o r t h e f o r m a -

t i o n o f t h e v o i d s .

A s g e n e r al b a c k g r o u n d f o r t h e f o l l o w i n g d i s c u ss i o n , it m a y b e b o r n e i n

m i n d t h a t g e o l o g i st s c o n c u r th a t t h e b a si c f o u n d a t i o n f o r m a t i o n i m m e d i a t e l y

b e n e a t h t h e r e se r v o ir is t h e I n g l e w o o d F o r m a t i o n , a s t ra t if i ed s e d i m e n t a r y

u n i t c o m p o s e d o f s i l t s to n e s , s a n d s a n d c l a y s t o n e s , a l l o f w h i c h w e r e o r i gi n al ly

b u i l t u p b y d e p o s i t i o n i n q u i e t s a l t w a t e r . A c c o r d i n g l y , t h e v o i d s p r e s e n t l y

e x i s t i n g c o u l d n o t h a v e b e e n o r i g i n a l l y p r e s e n t .

D E S C R I P T I O N O F V O I D S

A l l o b s e r v e d v o i d s h av e b e e n w i t h i n t h e v e r y n a r r o w , s h e a r e d , s t e e p l y d i p -

p i n g p l a n a r z o n e s c r e a t e d b y F a u l t s I , I I a n d V . T h e l o c a t i o n s o f t h e s e f a u l t s ,

a n d o f t h e t e s t e x c a v a t i o n s i n w h i c h t h e v o i d s h a v e b e e n s e e n , a r e s h o w n i n

f i g . l l o f L e p s ( 1 9 7 2 ) . R e f e r r in g t o th e l a y o u t o f t e s t e x c a v a t i o n s g iv e n

t h e r e o n , f o l l o w i n g i s a s u m m a r y o f t h e r e p o r t e d c a v it ie s .1 o r v o id s , m o s t o f

w h i c h w e r e r e c o r d e d o n P l a te s 2 2 a t o 2 2 m o f th e A p r il 1 9 6 4 R e p o r t o f th e

E n g i n e e ri n g B o a r d o f I n q u i r y c h a i re d b y R o b e r t B . J a n s e n .

1 Ad it 9

p e n e t r a t e d a l o n g F a u l t I f o r a d i s t a n c e o f 2 5 6 f t . t h r o u g h t h e

r ig h t a b u t m e n t o f t h e M a i n E m b a n k m e n t . I t w a s a t a l ev e l a b o u t 4 7 f t . b e l o w

t h e r e s e r v o ir f l o o r a n d 7 0 f t . b e l o w a b u t m e n t s u r f ac e , a t w h i c h l e v el i t w a s

r e l at i v e ly u n d a m a g e d b y t h e p r e s s u r iz e d o u t f l o w o f re s e rv o i r w a t e r w h i c h

c u t th r o u g h t h e ri g ht a b u t m e n t o n D e c . 14 , 1 9 6 3 .

* 1 C a v i t i e s o r v o i d s a re t e r m s i n t e n d e d to i d e n t i f y p r e - fa i lu r e f o u n d a t i o n v o id s .

E r o s i o n a l z o n e is a t e r m i n t e n d e d t o i d e n t i f y v o i d s i n t h e f o u n d a t i o n c a u s e d p ri n -

c i p a l ly b y o u t r u s h i n g w a t e r o n t h e d a y o f f a i lu r e .

0 0 1 3 - 7 9 5 2 1 8 7 ] $ 0 3 . 5 0 © 1 9 8 7 E l se v ie r S c i e n c e P u b l i s h e r s B . V .


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As this adit was excavated, 18 locations were noted where either: (a) the

fract ures with in and caused by Faul t I were o pen, up t o 1A inch; or (b)

small, open, lenti cula r cavities, up to 31/2 inches in diamete r, were present .

A significant number of instances was also noted wherein fractures had re-

cent ly been invaded by fo reign materials such as clay, pea gravel and asphalt,

thus indicating that generally the entire trace of F ault I along this reach

just prior to wa shout had been open to substantial depth, an inevitable con-

sequence of the horizon tal tension caused by subsidence.

2 . T r e n c h N o . 6 located 70 ft. north of the inspection chamber, exhibited

a large erosional zone just under the fractured pea-gravel drain and along

Fault I, subsequently nearly filled with foreign materials. Additional ly, a

small, lenticular cavity, isolated in an unidentified fracture zone near Fault I,

was also present.

3 . T r e n c h N o s . 7 E a n d 7 F located just south of the circulator pipes Wye,

exhibited a large erosional zone adjacent to the fractured concrete cradle and

tile pipe of Fault I drain.

4 . T r e n c h N o . 2 located about 70 ft. north of the boat stairway over

Faults I--II, exhi bite d a small lenticula r cavity abo ut 5 ft. below the gravel

drain an d adj acen t to Faul t II, as well as an extensive refilled erosional zone

on Fault II just under the gravel drain.

5 . T r e n c h N o . 8 located near the f oot of the boat stairway, as logged both

in 1964 and 1969, exhi bited small lenticula r and refilled cavities, similar to

those in Trench No. 2.

6 . T r e n c h e s N o s . 3 a n d 1 3 located near the center of the reservoir and

south o f the bot tom tile drains, exhibited a large cavity, apparently contin-

uous between the two trenches and lying along Fault V. At its apparent

maximum just north of No. 3, the cavity was several feet in diameter. It ex-

tended southerly from just under the pea-gravel drain at No. 13 to a level

ab out 7 ft. below the pea-gravel drain at No. 3. This was the largest open

cavity enco unte red in the explorati on program. No invasion of foreign solids

into it was seen, and it was reporte d t hat there was slight calcification on

the surface of the ca vi t y . . . .

MECHANISMS OF VOID FORMATION

As presented by Leps (1972), major areal subsidence, accompanied by

tensile openings in a horizontal sense across minor faults beneath and south

of the reservoir, and relative displacements at the faults in a vertical sense,

were occurring at the pre-existing faults, probably since about 1924, in the

natural strata below the reservoir. The tensile opening in a direction across

the lines of F aults I--II and V amo un ted to app rox ima tel y 1A inch per 100 ft.

of horizontal distance between 1950 and 1964. This means that if all of the

developing stretch in the west sub block (see fig .l l of Leps, 1972) westerly

of Fault V to the reservoir perimeter road had conc entrat ed at Fault V, tha t

faul t trace w ould have opened abo ut 11~ inches during the life of the reser-

voir. Since, however, the re is evidence to sh ow th at Faults V, I and II are


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p r o b a b l y j u s t t h e r e l a t i v e l y m a j o r f r a c t u r e s i n a s i n g l e s h e a r e d m a s s , w h i c h i s

f u r t h e r s u b d i v i d e d b y m a n y o t h e r s t e e p l y d i p p i n g s h e ar s a n d f r a c t u r e s , it is

u n d o u b t e d l y u n r e a s o n a b l e t o a l l o c a t e a ll t h e t e n s il e o p e n i n g t o o n e f a u l t

p l a n e . I n s te a d , i t w o u l d b e r e a s o n a b l e t h a t s u c h o p e n i n g w o u l d b e d i s tr i b u -

t e d t o m a n y f a u l t s a n d f r a c t u r e s , i n s u c h a f a s h i o n t h a t e a c h w o u l d a c c o m -

m o d a t e a f r a c t i o n o f t h e t o t a l , w i t h t h e m a j o r f a u l t p la n e s b e i n g t h e l o c u s o f

t h e l a r g e r i n c r e m e n t s .

S u c h a n a r r a n g e m e n t o f te n s i l e st r ai n s a p p e a r s t o b e v e ri f ie d b y a c t u a l o b -

s e r v a t i o n s , w h i c h h a v e s h o w n t h e f o l l o w i n g o p e n i n g s : F a u l t I I , l es s t h a n 1A

i n c h ; F a u l t I , a s m u c h a s ½ i n c h ; F a u l t V , a b o u t ~A i n c h .

T h u s i t is c l ea r t h a t a s o f D e c . 1 9 6 3 , a n d j u s t a s c e r t a in l y f o r m a n y y e a r s

p r i o r t h e r e t o , t h e p r i n c i p a l f a u l t p l a n e s p a s s i n g u n d e r t h e r e s e r v o i r w e r e

c h a r a c t e r iz e d b y v e r y n a r r o w b u t n e v e r t h e l e ss f i n i t e o p e n g a ps . T h e i r ex is -

t e n c e e v e n a t t h e t i m e o f re s e rv o i r c o n s t r u c t i o n is n o w f u r t h e r s u g g e s t ed b y

t e s t t r e n c h e x c a v a t i o n w h i c h h a s s h o w n t h e e x i s t e n c e o f l o c a l a s p h a l t s t ai n in g

a l o n g a f r a c t u r e i n s i l t s to n e b e l o w t h e a s p h a l t u n d e r s e a l , p r o b a b l y o c c u r r i n g

a t t h e t i m e t h e i n it ia l , l o w v i s c o s i t y , a s p h a l t s e a l c o a t w a s s p r a y e d o n t h e s u b -

g r a d e in 1 9 5 0 . I t is i m p r o b a b l e , h o w e v e r , t h a t a n y s h e a r p l a n e w a s o p e n

e n o u g h i n 1 9 5 0 t o b e d i sc e r n i b le b y t h e u n a i d e d e y e , es p e c i al ly in v ie w o f

t h e s u r f a c e d i s t u r b a n c e c a u s e d b y t h e g r ad i ng o p e r a t i o n s b e i n g c a r ri e d o u t i n

t h e a r e a .

T h u s t h e p r i m a r y m e c h a n i s m f o r o b s e r v e d v o i d s i n t h e f o u n d a t i o n , h o r i z o n -

t a l t e n s i o n , is e x p l a i n e d a n d v e r i fi e d. T h e s e c o n d a r y m e c h a n i s m w a s t h e e n -

l a r g e m e n t o f t h e p l a n a r v o i d s i n r a n d o m f a s h i o n w h e r e v e r f lo w i n g w a t e r

f o u n d i ts w a y i n t o t h e p r e - e x i s t i n g c r a c k s . I t a p p e a r s c e r t a i n t h a t t h i s s e c o n -

d a r y m e c h a n i s m s h o u l d b e s u b d i v i d e d i n to t w o c a t eg o r i es , as f o l l o w s .

( A ) V e r y s l o w , v e r y g r a d u a l , d o w n w a r d m i g r a t i o n o f s o il p a r t i c l e s o v e r a

p e r i o d o f y e a r s f r o m t h e o p e n w a l ls o f t h e f a u l t s a n d f r a c t u r e s , in r e s p o n s e

t o t h a t d o w n w a r d t r i c k l e l e ak a g e o f n o r m a l r e s er v o i r s e e p a g e p a ss i ng

t h r o u g h t h e c l a y li n in g , w h i c h l e a k a g e , in a f e w l o c a t i o n s , f o u n d a n d p a s s e d

t h r o u g h r u p t u r e s a n d i m p e r f e c t i o n s i n t h e a s p h a l t u n d e rs e a l .

( B ) V e r y r a p i d , v i o l e n t m i g r at i o n , b o t h d o w n w a r d a n d l a te r a ll y , o f so il

p a r ti c le s f r o m t h e o p e n w a l ls o f th e f a u l ts a n d f r a c tu r e s , i n r e s p o n s e t o t h e

s h o r t - t i m e , h i g h - v e l o c i t y lo s s o f r e s e r v o i r w a t e r t h r o u g h t h e f i n a l b r e a k o r

b r e a k s i n t h e r e s e r v o i r l i n i n g .

ANALYSIS OF EVENTS

F r o m h i n d s i g h t i t i s o b v i o u s t h a t , a t t h e t h r e e f a u l t s , t h e i n c r e a s in g t e n s i l e

s t ra i n s , t h o u g h s h g h t , a n d t h e i n c r ea s i n g v e r ti c a l o f f s e t s , w h i c h w e r e m a j o r ,

b e g a n t o d a m a g e a n y r i gi d, b r i t t le f e a t u r e s o f t h e r e s er v o i r a l m o s t a s s o o n a s

t h e r e s er v o i r w e n t i n t o o p e r a t i o n . T h e f o l l o w i n g l o c a t i o n s w e r e p a r t ic u l a r l y

i m p o r t a n t , b e c a u s e a t th e s e l o c a t i o n s t h e e a r ly f r a c tu r i n g a n d p a r t in g o f t h e

b r i tt l e , u n r e i n f o r c e d c o n c r e t e c r a d le s f o r t h e t il e u n d e r d r a i n s w h e r e t h e y p a s -

s e d o v e r th e f a u l t s m u s t h a v e al s o t o r n a n d p a r t e d t h e a s p h a l t u n d e r s e a l c o n -

c u r r e n t l y : ( 1 ) F a u l t V a t b o t t o m d r a i n s ; ( 2 ) F a u l t s I - - I I a t S . E . t o e d r a i n ; ( 3 )

F a u l t I a t f a u l t d r a i n ; ( 4 ) F a u l t I a t i n s p e c t i o n c h a m b e r .


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With respec t to locati on (1), DWP's M. & S. Chart .1, page 111, suggests

tha t as early as 1951 some vertical offs et was occurring at Fau lt V. Certa inly

by 1957 such offset, being on the order of 1 inch, was enough to crack and

open t he b ottom-dr ain cradle. Since normal seepage from over half of the

reservoir's clay lining woul d pass over such a crack on its way to the inspec-

tion c hamber, it is inevitable that some of the flow would filter down t hrough

the crack in the underseal and thence into Fault V.

In this conn ection, it is notable that the cradle at this point was underlain

by about 11~ ft. of compacted earth fill. A short distance to the south the

fill feath ered out, a nd to t he no rth the fill became muc h thicker. Evidence in

Trench No. 11 suggests that the fill never was cracked and opened by defor-

mations adjac ent to Fault V. Instead, the seepage water, escaping from the

cracked bo tt om drain at this point and in effect being slightly pond ed in the

area west of the vertical offset at V, flowed southerly over the feat her edge

of the fill, and the n dow n a nd laterally into the slightly open f ound ati on

shear zone at V. It was this continuing and slowly increasing seepage flow

into V in the vicinity of Trenches Nos. 13 and 3 that, over the years, eroded

out the largest cavity in the found atio n. The materials moved out of the

cavity were translated vertically downwar ds in the slightly open fault.

In regard to location (2), at the southeast corner of the reservoir, the same

mechanism as described above for location (1) was at work. The am oun t of

seepage available for dow nwa rd diversion was at this po int very small, how-

ever, so no sizeable cavities were developed. On the o the r hand, the Dec. 1963

ext ent of vertical offsett ing was sufficient at this location to open a gap com-

pletely through the gunite-topped, pea-gravel drain, into the cracked S.E. tile

drain, and on into the found atio n. With its protection against piping thus

destro yed, the clay lining was then perfora ted by piping action, and the

foundation via the Fault I--II complex as well as the tile pipe for the S.E. toe

drain were pressurized under full reservoir head. Muddy water violently

flowed throug h the S.E. drain and highly erosive flow passed downw ard and

nort hwar d along the Faults I--II complex.

With respect to location (3), at the fault drain, the cavity was erosional,

and was probably due both to long-term, slow, seepage loss through the frac-

tured concrete cradle at Fault I, and to short-term, violent flow on Dec. 14,

1963. T hat th e latte r occurred in this drain is know n. The source of the heavy

flow is not entirely certain, but it could have been the neighboring S.E. toe

drain pipe, which, as described above, had become pressurized and which

undoubtedly pressurized all nearby pea gravel. The two drains, i.e., fault and

S.E. toe, are only 14 ft. apart at this point.

In regard to location (4), at the inspection chamber, there is little doubt ,

tha t the vertical bending and cracking of the inspection chamber, where it

was off set by Faul t I vertical displacements, were severe enough to cause

ruptur e of the pea-gravel blanket, and its gunite topc oat and asphalt under-

,1 Los ngeles Department of Water and Power 's Measurem ents and Surveys Chart .


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c o a t , l o c a t e d ju s t 4 f t. o v e r h e a d . F u r t h e r m o r e , t h e v e r t ic a l o f f s e t s o f F a u l t I

o n e i th e r s i d e o f t h e c h a m b e r w e r e m e a s u r e d t o b e a l m o s t t w i c e t h a t m e a -

s u r e d w i t h i n t h e r ig i d c h a m b e r . T h u s , w i t h a s m u c h a s 61/2 i n c h e s o f l o c a l-

i z e d , d i f f e r e n t i a l v e r t i c a l d i s p l a c e m e n t h a v i n g o c c u r r e d , a n d w i t h a t l e a s t

21/~ i n c h e s h a v i n g b e e n c o n c e n t r a t e d i n D e c . 1 9 6 3 , t h e g u n i t e - p e a g r av e l-

u n d e r s e a l c o m p l e x w a s c o m p l e t e l y r u p t u r e d . T h i s a l l o w e d r es e r v o ir w a t e r to

c a u s e p i p in g t h r o u g h t h e c l a y l i ni ng a n d u n d e r s e a l , a n d t h e r e a f t e r t o s u b j e c t

t h e p l a n a r o p e n i n g a t F a u l t I t o f u l l r e s e r v o i r p r e s s u r e , e r o s i o n a n d d e t e r i o r a -

t i o n . A r e a d y e s c a p e f o r f l o w n o r t h e r l y i n F a u l t I t h r o u g h t h e r ig h t a b u t m e n t

f o l l o w e d r u p t u r e a t t h is p o i n t . S i m i la r a n d s i m u l t a n e o u s r u p t u r e c o u l d h a v e

o c c u r r e d a l o n g t h e 3 0 0 f t . r e a c h o f F a u l t I n o r t h e r l y f r o m t h is p o i n t ; o r a ll

s i n k h o l e s in t h a t r e a c h c o u l d h a v e b e e n t h e r e s u l t o f v i o le n t n o r t h e r l y o u t -

f l o w a n d e r o s i o n j u s t b e l o w t h e a s p h a l t u n d e r s e al . T h e f u l l p r e s s u r iz a t io n o f

t h e p e a g ra v e l a d j a c e n t t o t h i s r u p t u r e c o u l d e x p l a i n t h e v i o l e n t d i sc h a rg e

r e p o r t e d o n D e c . 1 4 f o r t h e N . E . d r a in , w h i c h p a s s e s as c l o s e a s 2 0 f t . t o t h e

r u p t u r e , a n d is a n o p e n j o i n t t i l e p i p e .

CONCLUSIONS

( 1 ) T h e u n d e r d r a i n s y s t e m , c o n s i s t in g o f a p e a - g ra v e l b l a n k e t w i t h a p e r -

v i o u s g u n i t e t o p c o a t a n d a n i m p e r v i o u s a s p h a lt u n d e r c o a t , t o g e t h e r w i t h a

s y s t e m o f p a r t l y e m b e d d e d t il e o u t f a l l p i p e s s u p p o r t e d o n c o n c r e t e c r ad l es ,

w a s s e r i o u s l y d a m a g e d b y p r o g r e s s i v e l y i n c r e a s i n g t e n s i l e s t r a i n s a n d v e r t i c a l

o f f s e t s c o n c e n t r a t e d a t c r o ss i n g s o f F a u l t s I , I I a n d V .

( 2 ) T h e o b s e r v a t i o n s i n t e s t A d i t 9 c o n c l u s i v e l y s h o w e d t h a t a n o p e n ,

t h r o u g h - g o i n g , p l a n a r v o i d e x i s t e d a l o n g F a u l t I i n 1 9 6 4 .

( 3 ) A t a f e w l o c a ti o n s , v e rt ic a l o f f s e t d a m a g e t o t h e u n d e r d r a i n s y s t e m

w a s s u f f i c i e n t to r u p t u r e t h e a s p h a l t u n d e r s e a l s o m e y e a r s p r i o r t o d e s t r u c t i o n

o f t h e r e se r v o ir a n d t h u s p e r m i t n o r m a l s e e p a g e t o t r ic k l e d o w n i n t o o p e n

f a u l t p l a n e s i m m e d i a t e l y b e n e a t h f o r an e x t e n d e d p e r i o d o f t i m e .

( 4 ) T h e l o n g -t im e s e e p a g e l os s i n t o f a u l t p l an e s , p r o b a b l y a m o u n t i n g t o n o

m o r e t h a n a f e w g a l lo n s p e r m i n u t e , c a u s e d l o c a li z ed e ro s i o n w i t h in t h e o p e n ,

n a r r o w f a u l t z o n e s , l e a d in g t o t h e f o r m a t i o n o f s m a l l l e n t i c u l a r v o i d s o r c av i-

t ie s . T h e m o s t p r o n o u n c e d o f th e s e c a v it ie s w a s o n F a u l t V n e a r th e c e n t e r

o f t h e r e se r v o ir ; b u t t h is c a v i t y , w h i c h w a s m a n y h u n d r e d t i m e s l ar ge r t h a n

a n y o t h e r l o n g - t e rm , s l o w - se e p a g e c a v i ty , in n o w a y c o n t r i b u t e d t o w a r d s t h e

a c t u a l d e s t r u c t i o n o f t h e r e s er v o ir .

( 5 ) N o n e o f t h e r e l a ti v e l y s m a l l, le n t i c u l a r, d i s c o n n e c t e d c a v i ti e s c a u s e d

b y s l o w , l o n g - t e r m s e e p a g e h a d a p a r t i n t h e a c t u a l d e s t r u c t i o n o f th e r e s e r v o i r.

( 6 ) T h e o p e n , t h r o u g h - g o i n g , p l a n a r v o i d s c r e a t e d i n t h e f a u l t p l a n e s b y

h o r i z o n t a l t e n s i o n p r o v i d e d a n i m m e d i a t e a n d h i g h l y e r o d i b l e e s c ap e a v e n u e

f o r r e s er v o ir w a t e r a f t e r u n a n t i c i p a t e d f a u l t v e rt ic a l o f f s e t s o f u p t o 7 i n c h es ,

o c c u r r i n g o v e r a p e r i o d o f 1 3 y e a r s , o p e n e d f r a c t u r e s i n th e u n d e r d r a i n s y s-

t e m s u f f i c i e n t l y t o p e r m i t p i p in g a c t i o n s t h r o u g h t h e c l a y l in in g .

( 7 ) T h e m a j o r f a u l t o f f s e t s w h i c h e v e n t u a l l y d e s t r o y e d t h e i n t e g r i t y o f t h e

u n d e r d r a i n s y s t e m w e r e d u e i n p a r t t o l o n g - t e r m s u b s i d e n c e , i n p a r t d u e t o


6/6

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differential fou nda tio n consolidation, and in part to re bound and retarded

subsidence of the east sub block caused by oil field repressuring south of the

reservoir. One episode of the measured and do cum ent ed rebounds, which

began five mont hs prior to the failure, amo unt ed to as much as 7/8 inch at

the wa ter ta nk just so uth of the reservoir at the time of failure. The addi-

tional displacement then occurring progressively northerly along Fault I is

visualized as just the final disruption of a seepage control system that had

already sustained near fatal damage.

REFERENCE

L e p s T h o m a s M . 1 9 7 2 . A n a l y s e s o f f a i l u r e o f B a l d w i n H i l l s R e s e r v o i r . P r o c e e d i n g s A S C E

S p e c i a l t y C o n f e r e n c e P u r d u e U n i v . V o l . I P a r t I.

failure of baldwin hills reservoir 1963 interpretation of step by step failure sequence 1987...

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