GP29 – Church Camp Landslide
Church Camp GP29
~250 m wide and ~200 m in length to the river Ponding water
Background • The river valley is a pre-glacial valley with drift deposits to about 50m- 100m depth. • It is unknown if the slide predated the highway possibly ancient deep seated landslide. • Highway was widened in 2013 for a new NBL likely constructed over backscarp. • Karl Engineering Consultants Ltd. Installed 3 Slope Inclinometers to 36 m and 3 piezometers • Primary cause due to river erosion at the toe and high ground water regime
Localized Landslides
2015 Lidar
Additional Geotechnical Investigation • Drilled 9 test holes auger and wet rotary • Three SIs installed to 51 m with 3 pneumatic piezometers to hopefully catch deep seated movement • Two SIs installed to 36 and 39 m deep with 2 pneumatic piezometers • Three tests holes 6.6 m to 11.1 m deep with standpipes for re-alignment information
6.6 m 6.6 m 36.1 m 51.2 m 51.4 m 11.1 m Gas Well Heads 51.4 m 39.2m 6.6 m
Findings from Investigation FIGURE 17102 PIEZOMETRIC DEPTHS FOR HWY 2:70 11.8 km SOUTH OF RYCROFT -10 PN17-3C -8 PN17-3B PN17-4B -6 PN17-1A -4 Frozen GROUNDWATER DEPTH (m) PN17-1B PN17-4C PN17-2A Ground Surface -2 PN17-2B PN17-2C PN17-3B 0 PN17-3C PN17-4A 2 PN17-4B PN17-4C PN17-5A 4 PN17-5B SP17-6 6 SP17-7 SP17-8 SP17-9 8 10 12 14/Aug/13 23/Sep/13 2/Nov/13 12/Dec/13 21/Jan/14 2/Mar/14 DATE
SI17-3 43 m (586.4 m elev.)
SI17-4 44.3 m (586.8 Elev.) Wasn’t read in January because pneumatics were frozen and stuck inside
Karl’s old SIs
Remedial Measures • Landslide is too large and deep for pile wall or toe berm • Re-alignment of the highway is most cost effective option • Well heads in farmers field will need to be taken into consideration • WSP will be completing the re-alignment design
70 m Setback 110 m Setback Well heads Bridge
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