EBA Engineering consulta~ts Ltd.

CHASE CREEK DETAILED TERRAIN STABILITY MAPPIN

(TSIL C) RIVERSIDE FOREST PRODUCTS LIMITE

ARMSTRONG DIVISION

EBA Project No. 0801-00-81159

#255, 1715 Dickson Ave., Ke/owna, a.c.1 Canada V1Y 9G6 • Telephone: (250) 862-4832 • Fax: (250) 862-294f • Intemet: kelowna@eba.ca

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DETAILED TERRAIN STABILITY ~PING (TSIL C)

CHASE CREEK

SALMON ARM FOREST DISTRICT

Prepared by:

EBA ENGINEERING CONSULTANTS LTD. Kelowna, B.C. I

Submitted to: , Riverside Forest Products ~imited

Armstrong Division I I

EBA Project No. 0801-0q-81159 I

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June, 2001

This project has been rt.Jded by FOREST RENEWAL BRITISH COLUMBIA

TABLE OF CONTE TS PAGE

1.0 IN'TRODUCTION ................................................ ~ ...................................................... 1

2.0 METHODOLOGY ............................................... f ...................................................... I 2.1 Terrain Mapping ...................................... t ...................................................... 1 2.2 Description of the Interpretive Classes ............................................................. 3

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2.2.1 Terrain Stability Class .................. ,' ....................................................... 3 2.2.2 Soil Erosion Potential Class ......... ! ....................................................... 4

2.2.3 Likelihood of Landslide Debris Entering ~treams Class ................................ 5 2.2.4 Potential for Sediment Delivery from Soi~ Erosion Sources Class ................. 6

3.0

2.3 Mapping Reliability .................................. ! ....................................................... 6

REGIONAL PHYSIOGRAPHY ........................ ..1. ...................................................... 8

4.0

3.1 Topography and Bedrock Geology .......... ~ ....................................................... 8 3.2 Regional Landscape Evolution ant;! DepOjition of Surficial Materials ........... 9

SURFICIAL MATERIALS AND ASSOCIATEID LANDFORMS ......................... 10 4.1 Till (M) .................................................... 1 .............................••...................... 10 4.2 Glaciofluvial Materials (FG) ........................................................................ 11 4.3 Colluvium (C) ............................................................................................... 12 4.4 Fluvial Materials (F) ..................................................................................... 13 4.5 Glaciolacustrine Materials (LG) ................................................................... 13 4.6 Weathered Bedrock (D) ................................................................................ 14 4.7 Organic (0) ................................................................................................... 14

5.0 ACTIVE GEOMORPHOLOGICAL PROCESS S .................................................. 14 5.1 Rapid Mass Movement (-R, -R") and Slo, Mass Movement (-F, -F")

5.1.1 Debris Slides (-Rs, -R"s), Debris Flows (-Rd, -R"d) and Slump ...... 15 in Surficial Materials (-R"u)........ ..................................................... 15

5.1.2 Rockfall (-Rb, -R''b) ......................................................................... 16 5.1.3 Tension Cracks (-F"k) ...................................................................... 16 5.1.4 Slump in Bedrock (-F"m) ............ 1 ..................................................... 17

5.2 Gully Erosion (-V) ................................... j ..................................................... 17 5.3 Glacial Meltwater Channels (-E) ............. I ....................................................... 17 5.4 Abundant Seepage (-L) ................................................................................. 18

6.0 IN'TERPRETIVE CLASSES - DISCUSSION MANAGE:MENT IMPLICATIONS ...................................................................................................... 18 6.1 Terrain Stability Class .................................................................................. 18 6.2 Soil Erosion Potential Class ......................................................................... 19 6.3 Terrain Stability and Soil Erosion Poten al- Management Implications ..... 20 6.4 Likelihood of Landslide Debris Entering treams Class .............................. 21 6.5 Potential for Sediment Delivery from So' Erosion Sources Class ............... 21

7.0 RECOMMENDATIONS ..................................... ~ .................................................... 22

8.0 i ACKNOWLEDGMENTS .................................... ~ .................................................... 24

9.0 REFERENCES .................................................... l ................................................... 24

10.0 CLOSURE ............................................................ ~ .................................................... 26

FIGURES

Figure l ......................... Location Map and Previous MaJping Projects in Adjacent Watersheds Figure 2 ............................................................................ r ................................ Traverse Routes

TABLES

Table 2.1 - TRIM Sheet and Air Photograph List ........... ~ ....................................................... 3 Table 2.2 - Terrain Stability Mapping Projects Complet~d in Watersheds Adjacent

to the Chase Creek Study Area .............................................................................. 3 Table 2.3 - Guidelines for the Assessment of Detailed Tbrrain Stability Classes

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Chase Creek Area .......................................... ~ ................................... ~ ................... ·4 Table 2.4 - Guidelines for the Assessment of Soil Erosior Potential Classes

Chase Creek Area .................................................................................................. 5 I

Table 2.5 - Field Checking Statistics for the Crown Land Portion of the Chase Creek Study Area ................................ l ....................................................... 7

Table 5.1 - Stratigraphy of the Upper Chase Creek VaUdy Slide Between Sites PU60 and PU231 ................................ .. l ......... ............................................ 16

Table 6.1 - Management Implications of Detailed Terrafu Stability Classes ........................ 20 I

Table 6.2 - Management Implications of Soil Erosion Potential Classes ............................. 21 Table 6.3 - Implications of Likelihood of Landslide Debrs Entering Streams Class ........... 21 Table 6.4 - Implications of Potential for Sediment Delivery from Soil Erosion

Sources ClasS ................................................ -j-... _ ............................................... 22

APPENDICES .

Appendix A .................................................................... .l. .................... Annotated Photographs Appendix B ..................................................................... J ............................................... Legend Appendix C ...................................................................... l ....................................... Field F011l1s

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0801-00-81159 - 1 - June 12, 2001

1.0 INTRODUCTION

The objective of this project was to prepare det~iled terrain stability maps for Chase Creek with interpretations for terrain stability class, soil erosion potential class, likelihood of landslide debris entering streams class and potential for sediment delivery from soil erosion sources class. EBA IEngineering Consultants Ltd. (EBA) conducted pre-typing for the entire Chase Cree4 Watershed which was completed in March 1999. Between May 1999 and March 2000, EBA completed the field work and map production for Chase Creek's largest tributary, called Charcoal Creek. F or the current project, EBA completed the field work and map production for the remainder of the Chase Creek watershed between June 2000 and March 2001. EBA completed this work for Riverside Forest Products Limited, Armstrong Division with funding provided by Forest Renewal British Columbia (FRBC). The current project updates terrain stability mapping completed for the Chase Creek watershed by Dobson Engineering Ltd in 1996.

The Chase Creek watershed is situated about ~O km west of Salmon Arm, BC (see Figure 1). Part of the Thompson River system, the upper reach of Chase Creek flows west from the Fly Hills to Pillar Lake, then southwards to the town of Chase. The study area covers an area of 21,120 hectares and excludes its largest tributary called Charcoal Creek.

2.0 METHODOLOGY

2.1 Terrain Mapping

The terrain mapping was carried out in 3 basic phases: i) review of resource information and initial air photo interpretation; (ii) fieldwork and final typing; and, (iii) data entry, map compilation, editing, repot1 writing and review. To initiate the project, the following pertinent geo-physical mapping resources were obtained:

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• Colour Air Photographs, 1:17,000 scale, 1994.

• Surficial Geology, Shuswap Lake, BC, Map i391A, GSC, scale 1: 126,720. I

• Bedrock Geology of the Thompson-Shuswap-Okanagan area, BC; GSC, 1979, OF 637,1:250,000.

• Terrain Stability Mapping of the Chase Cfeek watershed (Dobson Engineering Ltd., 1996).