The Baldwin Hills Reservoir Failure in Retrospect Prepared Discussion 1987 Engineering Geology

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Engineering Geology, 24 (1987) 89--92 89Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

THE BALDWIN HILLS RESERVOIR FAILURE IN RETROSPECT*P R E PA R E D DISCUSSION

THOMAS M. LEPSConsulting Civil Engineer, P.O. Box 2228, Menlo Park, Calif. 94026 U.S.A.)(Accepted for publication December 1986)

The paper by Casagrande et al. (1972) has been reviewed by the present

writer with t he benefit of unusually detailed acquaintance with the docu-ment ed design, construction and perfo rmance, but no original involvementin the design and c onst ruct ion of the reservoir. This review also has the tem-pering benefit of over 20 years of hindsight.

One aspect of the paper t hat emerges time and again is the appar ently ir-resistible ten den cy to make qualitative statements of judgment which would,if used in court, have been support ive of the interests of the aut hor s' clients,Standa rd Oil Co. and others. The following review will be basically restrictedto reactions to those qualitative statements, but will, by implication, compli-ment the authors on their excellent presentation of factual descriptions and

performance data, by not comment ing on that aspect of their paper.

I tem 1

On p.551, the autho rs state unequivocally, Early on the day of failure,port ions of the reservoir lining collapsed into large voids formed by longterm piping. This stateme nt is no more than misleading speculation in thatthere were no large void s related to long term, tr ick le seepage actual lyfou nd in the fo und ati on except in Fault V, about 70 ft. south of the southbottom drain, where an open cavity up to 3 ft. in diameter and 30 ft. long,in and along the trace o f F ault V, was discovered to exist, generally a fewfeet under the asphalt membrane. The reservoir lining had not collapsed intothis cavity despite its size. All other cavities foun d in the postfailure explora-tion, except those eroded on the day of failure, were no larger than 1% ofthe Fault V cavity. Accordingly, the implicatio n of the exi stence of pre-existing or seepage-created large voids in the f ou nda ti on is unsu ppo rte d b ydirect observati on, but might certainly have served the client's interests indiverting attention from the subject of subsidence effects. The same mis-placed emphasis on, and exaggeration of, ...Large erosional cavities andpipes... appears again at the b ott om of p.568. Note tha t no dimensions werequoted, so the reader must guess what Lar ge means.

*By Casagrande et al., 1972.

0013-7952/87/$03.50 © 1987 Elsevier S c i e n c e P u b l i s he r s B.V.


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I t e m

O n p . 5 7 0 , t h e a u t h o r s s t a te : . . .R e g i o n a l s u b s i d e n c e o r u p l i f t is c a u s e d b yt e c t o n i c s , o il fi e ld o p e r a t i o n s , a n d p o s s i b l y b y o t h e r a s y e t u n i d e n t i f i e d

c a u s e s . . . F i r s t, i t i s a g r e e d t h a t r e g i o n a l s u b s i d e n c e h a s b e e n r e p e a t e d l y i d e n -t i f i e d a s h a v i n g b e e n t h e r e s u l t o f o i l f i e ld o p e r a t i o n s ( p r o d u c t i o n o f o i l, g a sa n d w a t e r ). S e c o n d , t e c t o n i c a d j u s t m e n t s in a g e o l o g ic ti m e f r a m e c h a ra c -t e ri s ti c a ll y a re k n o w n t o h a v e c a u s e d m a j o r b l o c k s to m o v e u p w a r d , d o w n -w a r d a n d s i d e w a y s , b u t e x t r e m e l y s l o w l y. T h i r d, t h e r e i s c le a r e v i d e n c e t h a tl o c a l iz e d , d i f f e r e n t i a l u p l i f t h a s b e e n c a u s e d b y o i l f i e ld o p e r a t i o n s , s p e c if i -c a l ly b y p r e s s u r e i n j e c t i o n o f b r i n e i n t o t h e o i l a n d g a s p r o d u c i n g h o r i z o n s .F o u r t h , s u b s i d e n c e d u e t o g r o u n d w a t e r w i t h d r a w a l is w i d e l y re c o g n i z e d .F i f t h , w h a t p u r p o s e i s s e r v e d b y r ai s in g t h e i ss u e t h a t . . . o t h e r a s y e t u n i d e n -t i fi e d ca u s e s .. . r e s u l t i n s u b s i d e n c e o r u p l i f t, e x c e p t h o p e f u l l y t o i n t r o d u c ea n e l e m e n t o f u n c e r t a i n t y.

I t e m 3

O n p . 5 7 3 , th e a u t h o r s s ta t e : . . . T h e a u t h o r s c o n c l u d e t h a t s ha r p d i f fe r e n -t ia l s e tt l e m e n t s o f a b o u t 0 . 2 t o 0 . 3 f o o t d e v e l o p e d a c r o s s F a u l t I w e l l i n ad -v a n c e o f f a i l u r e, a s a r e s u l t o f c o m p r e s s i o n o f t h e l o o s e r s o il s l o c a t e d i m -m e d i a t e l y W e s t o f F a u l t I , a n d n o t b y F a u l t d i s p l a c e m e n t . . . O t h e r e q u a l l yw e l l q u a l i f i e d e x p e r t s , ( i .e ., C a st le a n d Y o u d , 1 9 7 2 ) , h a v e c o n c l u d e d t h a t t h es u r f a c e e x p r e s s i o n o f b l o c k m o v e m e n t s a d j a c e n t t o F a u l t s I , I I a n d V, a s d e -f i n e d b y a v a i la b le s e t t l e m e n t s u r v e y s a r e fu l l y e x p l ai n e d b y c o n s o l i d a t i o n o ft h e o i l p r o d u c i n g h o r i z o n s a t d e p t h , n o t b y sh a ll o w c o n s o l i d a t io n o f l o o s e rs o il s . S i n ce t h e r e i s n o a b s o l u t e p r o o f o f e it h e r c o n c l u s i o n , i t s e e m s o n l yf a ir t o c o n c l u d e t h a t b o t h m e c h a n i s m s m a y h a v e c o n t r i b u t e d , i n c lu d i n g d is -t o r t i o n c a u s e d b y t h e u p l i f t m e c h a n i s m i n v o lv i n g fu l l- s ca l e, h i g h - p r e ss u r e ,b r i n e in j e c t io n i n t h e o i l p r o d u c t i o n h o r i z o n s w h i c h w a s c a r ri e d o u t a f t e r1 9 5 7 b y t h e o il f i e ld o p e r a t o r s . I n c i d e n t a l l y, t h e s m a l l e a r t h q u a k e s o f F e b . 1 8 ,1 9 6 3 a n d M a r c h 1 0 , 1 9 6 3 , w h i c h d a m a g e d o i l w e l l c as in g s in th e p r o d u c i n gz o n e s w e r e u n d o u b t e d l y c a u s e d b y t h e b r i n e i n j e c ti o n p r o g r a m . S u c h e v e n tsa r e w o r t h y o f c a r e fu l c o n s i d e r a t i o n w h e n e v a lu a t in g u p l i f t ea s t o f F a u l t I .

O n e v e r y i ll u m i n a ti n g p e r f o r m a n c e r e c o r d w h i c h t h e a u t h o r s m a y n o th a v e n o t i c e d is i l l u s tr a t e d i n t h e i r f i g . 1 2 , p . 5 7 3 , a s f o l l o w s : D i f f e r e n t i a ls e t t l e m e n t o f t h e s o u t h p a r a p e t w a l l , w h i c h c r o s s e s F a u l t s I a n d V, h as in -c r e a s e d s t e a d i l y s i n c e t h e 1 9 6 3 f a i l u r e p e r i o d , d e s p i t e t h e f a c t t h a t l o a d i n g o ft h e l o o s e r so i l s b y r e s er v o ir w a t e r c e a s e d in D e c . 1 9 6 3 . D o e s t h is n o t m e a nt h a t a ll d i f f e r e n t i a l a s p e c t s o f t h e s e t t l e m e n t p r o f i l e s in c e th a t d a t e a r e d u et o s u b s id e n c e - c a u s e d , b l o c k m o v e m e n t r a t h e r t h a n c o m p r e s s i o n d u e t o re se r-v o i r l o a d i n g ?

I t e m 4

T h e a u t h o r s ' f i g . 15 , p . 5 7 8 , e x h i b i t s c o n t o u r s o f s u b s i d e n c e b e t w e e n 1 9 5 0a n d 1 9 6 3 . T h i s i n t e r p r e t a t i o n is g r o s s ly m i s le a d i n g i n t h a t i t p r e s e n t s o n l y


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average contour s, with no recogni tion of the strong irregularities th at wereevidenced at each o f th e t hree fault traces. These irregularities, which amoun-ted to offsets of as much as 0.5 to 0.6 ft., were of the same order of magni-tude as the s moot hed contours, and hence totally invalidate the impression

conveyed by the contours of gentle, regional tipping.

I tem 5

On p.581, the auth ors state: ...Th e authors, however, find no convincingevidence tha t a ny fault m oveme nt occurred under the reservoir prior tofailure... Perhaps the authors failed to consider the detailed settlementrecords for the bench mark on Pier 1 of the elevated water tank located onthe block east of Fault I, over 500 ft. south of the reservoir, and sufficientlydist ant to be ind epe nde nt of reservoir loading and leakage effects. The rec-

ords show that this bench mark rebou nded 0.05 ft. between July 1 andSept. 15, 1963, and rebounded another 0.01 ft. by Nov. 15, 1963. It did notsettle back to its master regional subsidence trend curve for 18 m onth s. Thisremarkable amou nt of rebound , shown by set tlement records for the inlettunnel and inspection chamber to have been concent rated east of Fault I,can logically onl y be ascribed to the oil field brine injection oper ations tothe sou th of the water tank. It chronologically just preceded, but is entirelycompatible with, the larger amou nt of rebound measured at the east side ofFault I at the reservoir on Dec. 17, 1963. T hat r ebou nd, of as muc h as0.18 ft., was clearly due t o the comb ined remo val of (a) reservoir loadingand (b) the block uplift recorded at the water tank which was progressingslowly northerly from the injection well area.

On p.581, the author s repeat: ...Th e author s, however, find no convincingevidence tha t a ny fault movem ent occurred under the reservoir prior tofailur e... Afte r reviewing the foregoing discussion, one wonders if th ey wouldnow agree that fault movem ent at the reservoir's Fault I un do ub te dl y occur-red during the 24 h prior to failure, and may well have contributed the finalincrement of foun dati on distortion which permitted piping to commence.

I tem 6

On p.585 the aut hors state: ...Ther e is no evidence tha t vertical displace-ments along faults have occurred at the time of failure anywhe re in theBaldwin Hills... It is suggested by this discusser th at th e record q uot ed inItem 5 strongly disputes that conclusion. Furthermore, there is an extensiverecord of prior surface cracks and vertical differ ential displacements alongsubsidiary and subparallel minor fau lts south of the reservoir during theperiod 1959- -1963 (see Grant IV, 1968). These sub-fault-block displacementswere highly evident across paved areas and stru ctures in the vicinity of LaBrea Avenue, Stocker Avenue and Overhill Drive. Vertical offsets of up to11/2 inches were repo rte d. Paving repairs were made fr equ ent ly. Some of thi ssurface response was ascribed by Grant IV to rebou nd coin ciden t with nearby


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The Baldwin Hills Reservoir Failure in Retrospect Prepared Discussion 1987 Engineering Geology