SOUTHERN REGION GRMP SITE INSPECTION FORM Slope movement has - PDF document

SOUTHERN REGION GRMP SITE INSPECTION FORM SITE NUMBER AND NAME: HIGHWAY & KM: PREVIOUS INSPECTION DATE: S039 - I & II Brocket Slides 3:06, 12.952 & 13.062 INSPECTION DATE: May 10, 2019 May 3, 2018 LEGAL DESCRIPTION: NAD 83 COORDINATES: RISK ASSESMENT: 09/10-07-007-28 W4M UTM Northing Easting PF: 10 CF: 4 TOTAL: 40 12 5491976 298990 AVERAGE ANNUAL DAILY TRAFFIC (AADT): CONTRACTOR MAINTENANCE AREA (CMA): 4,700 (west), 4800 (east), (Ref. No. 84050) 24 SUMMARY OF SITE INSTRUMENTATION: INSPECTED BY: Chris Gräpel (KCB) 3 slope inclinometers and 2 vibrating wire piezometers Chris Morgan (KCB) Alex Frotten (AT) Roger Skirrow (AT) Nicolas Ropchan (AT) LAST READING DATE: May 2019 PRIMARY SITE ISSUE: Natural slope landslide encroaching on west lane of highway. APPROXIMATE DIMENSIONS: S039-I: Landslide approximately 45 m wide at edge of westbound lane (undermining edge of pavement), overall width of slide zone is approximately 135 m. Landslide slope sloped at 1H:1V to 1.5H:1V for upper 3 m below edge of pavement, flattens to 2H:1V to a mid-slope bench. Overall slope of 2H:1V from crest to toe. Slope greater than 50 m high. S039-II: A smaller slide on upper 10 m of natural slope, head scarp 2 to 3 m high, head scarp located approximately 10 m from edge of pavement. Natural slope adjacent to slide sloped at approximately 2H:1V. DATE OF ANY REMEDIAL ACTION: Pavement patching, crack filling, and installation of a curb to limit pavement runoff from flowing onto landslide and subsequent repair in 2015. Gravel has been dumped over the guard rail onto the head of the slide to reduce the height of the head scarp. Instruments were installed in November 2016 and additional patching and curb repairs were carried out in 2017. NOTICABLE CONDITION CHANGE ITEM EXISTS DESCRIPTION AND LOCATION FROM LAST INSPECTION YES NO YES NO Cracks extending 1 to 2 m from guard rail into westbound X X Pavement Distress lane over a 20 m length. Ongoing movement, cracks opening at crest of slide, in X slide mass, and along west flank. Slide extends X Slope Movement downslope, failure block/bench at mid slope height. Runoff from highway is causing erosion near head of Erosion X X slide and on non-vegetated surfaces. Seepage noted on left (west) flank of slide and dense X X Seepage vegetation noted on right (east) flank of slide. X X Culvert Distress COMMENTS Main slide has impacted the highway. Pavement cracking in 2019 was generally unchanged from the 2018 inspection. The 2017 patching has cracked. Cracks are a couple of inches wide and deep, and partially collapsed. Page 1 of 2

SOUTHERN REGION GRMP SITE INSPECTION FORM Slope movement has extended onto the pavement and cracks have reached the white line. Cracking of highway surface indicates that retrogression of head scarp into the highway lanes will continue. Water flow off the highway is eroding the placed gravel. Ongoing need for patching and asphalt curb repair. Seepage inferred at slide location based on dense vegetation zone at east flank. Seepage observed on the access road constructed for drilling investigation. Bench in slide mass located approximately mid slope and appears to be the location of the failure plane just above the elevation of bedrock outcrops on natural slopes on flanks of slide zone, with the slide mass falling to the toe of the natural slope. Vegetation (shrubs, grass) present on slide mass except where cattle trails, landslide cracking and scarps are present. Numerous tension cracks and scarps present on slide mass. The access roads constructed for drilling have revegetated. Cattle trails on slide are obscuring some of the tension cracks. The second site (S039-II) is located to the east of the main slide site. Small slide in upper slope which extends into the ditch, causing runoff to flow onto the slide area. The second site was not inspected in 2019. In the short-term, the asphalt curb should be reestablished as required to limit pavement drainage onto the slide zone. The curb may need to be protected from snowplows by a high-tension-cable barrier. Design of remedial measures and preparation of tender documents has been completed by KCB. The proposed repair option includes soil nails and surface mesh to stabilize the highway embankment. Page 2 of 2

Alberta Transportation S039 - I & II Brocket Slides Southern Region GRMP Hwy 3:06, km 12.952 & 13.062 Photo 1 Pavement cracking across the highway proximal to the slide. Photo was taken facing west on May 10, 2019. Photo 2 Head scarp impacting the highway. The 2017 patching has cracked. Photo was taken facing west on May 10, 2019. 2019 S039 Inspection Photos.docx Page 1 A05115A03 July 2019

Alberta Transportation S039 - I & II Brocket Slides Southern Region GRMP Hwy 3:06, km 12.952 & 13.062 Photo 3 Instrumentation installed on a bench constructed mid slope in the middle of the slide area (red circle). Photo was taken facing northeast on May 10, 2019. Photo 4 Cracks on the ground on instrumentation bench, partially infilled due to sediment runoff and vegetation. SI readings indicate movement is directed approximately 40° from the downslope direction (perpendicular to the cracking). Photo taken facing northeast on May 10, 2019. 2019 S039 Inspection Photos.docx Page 2 A05115A03 July 2019

Alberta Transportation S039 - I & II Brocket Slides Southern Region GRMP Hwy 3:06, km 12.952 & 13.062 Photo 5 Head scarp of slide to the west of the main slide area, located between the highway and fence line. Photo was taken facing northwest on May 10, 2019. 2019 S039 Inspection Photos.docx Page 3 A05115A03 July 2019

³ NORTHWEST TERRITORIES BRITISH COLUMBIA High Level Pincher Creek ! Fort McMurray ! SASKATCHEWAN Grande Prairie ! Main landslide Edmonton Approximate location ! of bedrock outcrop Red Deer Approximate location ! of bedrock outcrop D Slide Calgary D ! D D Project Location ^ _ ! Lethbridge BH16-04B (SI) BH16-04A (VW) D U.S.A BH16-03 (SI) ? " 5 " 5 To Brocket 09-28 W4M 09-29 W4M " BH16-01 (SI) 5 Hwy 3:06 08-28 W4M D 08-29 W4M D To Jct Hwy 785 Asphalt curb U V V U 510 3 BH16-02 (VW) ? ! Chokio 07-28 W4M 07-29 W4M _ ^ U V ! 785 Brocket Pincher ! File: Z:\A\EDM\A05115A03 ABT Southern Region GRMP\400 Drawings\2019\2. Section B\MXD\S039_190527.mxd U V ! 06-28 W4M 06-29 W4M U V 507 786 U V 6 05-29 W4M 05-28 W4M ! Hartleyville Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community Legend Metres 0 100 ? Vibrating Wire Piezometer CLIENT PROJECT NOTES: SOUTHERN REGION GEOHAZARD RISK MANAGEMENT PROGRAM 1. HORIZONTAL DATUM: NAD83 " Slope Inclinometer 5 2. GRID ZONE: UTM Zone 12N 3. IMAGE SOURCE: World Imagery, ArcGIS Online. TITLE Source date: January 2015. Site Plan Slide S039 - West Brocket Slide Date: June 13, 2019 Time: 16:39:12 PM Flow Direction Hwy 3:06, km 12.952 SCALE PROJECT No. FIG No. A05115A03 1 1:2,000