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P A R T C: S E P T E M B E R 2 3 M O N I T O R I N G L A N D S L I D E R I S K A S S E S S M E N T

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P E A C E R E G I O N ( P E A C E R I V E R V A L L E Y / H I G H L E V E L ) SITE PH10: EUREKA RIVER (SOUTH OF WORSLEY) L E G A L L O C A T I O N : 8 6

8
W

6 M L

c

a t i

n

a l

n

g H i g h w a y : S t a t i

n

1 + 6 AT F I L E : S H 7 2 6 : 2 Station 1 0+600 T h e s l i d e w a s i n v e s t i g a t e d b y T h u r b e r E n g i n e e r i n g L t d . f

r

t h e M D . T h u r b e r i n s t a l l e d t w

s

l

p

e i n c l i n

m

e t e r s , E R 9 8

1

a n d E R 9 8

2

, w h i c h w e r e a d d e d t

t

h e m

n

i t

r

i n g s c h e d u l e i n O c t

b

e r

f

2 . T h r e e s l

p

e i n c l i n

m

e t e r s d e s i g n a t e d a s E R 2

1

t h r

u

g h E R

2
3

w e r e i n s t a l l e d in S e p t e m b e r 2 2 . Observations S l

p

e i n c l i n

m

e t e r E R 9 8

1

is l

c

a t e d d

w

n h i l l

f

t h e r

a

d t

w

a r d s t h e t

e
f

t h e s l

p

e . I t d i d n

t

r e c

r

d a n y d i s t i n c t m

v

e m e n t z

n

e s . I t , h

w

e v e r , s h

w

e d p

t

e n t i a l t i l t i n g , w h i c h w a s a n i n d i c a t i

n

t h a t t h e m

v

e m e n t z

n

e m a y b e d e e p e r t h a n t h e i n s t r u m e n t t i p . S l

p

e i n c l i n

m

e t e r E R 9 8

2

, l

c

a t e d at t h e t

p
f

t h e s l

p

e , r e c

r

d e d s u r f i c i a l m

v

e m e n t s w i t h i n t h e u p p e r

3 m

. T h e m

v

e m e n t r a t e w a s a p p r

x

i m a t e l y 1 7 m m p e r y e a r . S l

p

e i n c l i n

m

e t e r E R 2

1

, l

c

a t e d d

w

n h i l l

f

t h e r

a

d , r e c

r

d e d m

v

e m e n t in a d i s t i n c t s h e a r z

n

e a t 1 6 m d e p t h . T h e m

v

e m e n t r a t e w a s a p p r

x

i m a t e l y 1 5 5 m m p e r y e a r ; s u b s t a n t i a l l y h i g h e r t h a n t h e 6 5 m m p e r y e a r r e c

r

d e d i n M a y 2 3 . I n c l i n

m

e t e r E R 2

2

l

c

a t e d f u r t h e r d

w

n h i l l c l

s

e r t

t

h e E u r e k a R i v e r a l s

r

e c

r

d e d d i s t i n c t s h e a r m

v

e m e n t a t 9 m d e p t h . T h e m

v

e m e n t r a t e h a d a c c e l e r a t e d t

7

8 m m p e r y e a r , c

m

p a r e d t

6

m m p e r y e a r i n M a y . I n c l i n

m

e t e r E R 2

3

i s l

c

a t e d d

w

n h i l l f r

m

t h e r

a

d t

t

h e n

r

t h

f

E R 2

2

. I t i n d i c a t e d a d i s t i n c t m

v

e m e n t z

n

e at 9 m d e p t h . T h e m

v

e m e n t r a t e w a s 3 m m p e r y e a r , d

w

n f r

m

7 m m per year in May. T h r e e p n e u m a t i c p i e z

m

e t e r s w e r e a l s

i

n s t a l l e d i n S e p t e m b e r 2 2 t

m
n

i t

r

p

r

e w a t e r p r e s s u r e s . T h e p i e z

m

e t e r s w e r e r e a d

n

S e p t e m b e r 2 7 , a n d t h e r e c

r

d e d p

r

e p r e s s u r e s a r e s u m m a r i z e d i n t h e f

l

l

w

i n g t a b l e . T h e d a t a i n d i c a t e s n

s

i g n i f i c a n t c h a n g e i n p

r

e w a t e r p r e s s u r e s s i n c e J u n e 2 3 .

Plezom lnstrume Depth Pore Water Pressure (kPa) eter No. nt 1 .0 . (m)

Sept. 24, 2002

June 2, 2003

Sept. 27, 2003

ER 02-1 2771 2 10 33 53 52 2771 0 19 32 31 28 E R 02-2 27711 14.5 4 5 7

P.IPROJECTS\6600\Eg08628\Par1 C - Sept 200316628 Site PH tO Eureka Par1 C_Sept 2003 doc

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The condition of the road section within the slide area has deteriorated significantly over the past few years. The road surface experienced extensive pavement cracks and settlement, and had to be patched three times since 2001 ; in September 2001 , in the summer of 2002, and in the summer of 2003. In September 2003, the newly patched road experienced further settlement in the vicinity of inclinometer ER-98-2, but no pavement cracks were observed. Downhill from the road, ground cracks became wider (up to 40 mm) and deeper (up to 500 mm). The slide scarp became more defined particularly in the vicinity of slope inclinometers ER02-2 and ER02-3. Interpretation The existing shallow slope inclinometers (ER98-1 and ER-98-2) did not show any distinct shear zones, even though the slide has been active for several years. Data from the deep slope inclinometers installed in 2002 (ER02-1, ER02-2, and ER02-3) confirmed that the slide is deep-

seated. The data also suggests the slide is one large slide extending from the road to the

Eureka River, rather than several shallow slumps. The monitoring data and field observations indicate that the slide is active with a steady or increasing rate of movement. The recorded movement rates in September 2003 ranged between 78 and 155 mm per year, which is considered to be a high rate of movement compared to other sites. Should the movement rates remain that high, the condition of the newly patched road is likely to deteriorate. It is also anticipated that slope inclinometers ER02-1 and ER02-2 would shear off in the near future. Since the boundaries of the slide extend across the road, any significant slide movement is likely to cause traffic disruption. It is recommended that remedial measures be designed and implement at this site.

P·\PROJECTS\86001Eg086281Par1 C ·Sept 2003\8628 Site PH10 Eureka Par1 C_Sept 2003. d

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Alberta Transportation - Instrumentation Monitoring Results

PROJECT: Eureka (Stn. 10+600) FILE NAME: ER98 MAPID: PH10 Instrument Reading Stickup Ground Azimuth Monitoring Location of Rate(s) of General comments I. D. Depth (m) Elevation A+ Groove Date movement movement (m) (m)

fr. Mag.North

zone(s) (mm/year) (m)

14 Sept27, 2003 0-2.5 Apperantly some tilting is occurring, ER98-1 no clear distinct movement zone ER98-2 14 Sept27,2003 0-4 17 Surficial movement ER 02-1 27.1 Sept27,2003 16-17 155 Movement along a distinct shear zone Movement rate accelerated substantially since May 2003 ER 02-2 21 .1 Sept 27, 2003