STONY PLAIN REGION GEOHAZARD RISK ASSESSMENT SITE INSPECTION FORM HIGHWAY AND KM: Hwy 621:02, km 16.39

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1 SITE NUMBER AND NAME: NC 52 Pembina River Bridge LEGAL DESCRIPTION: SE W5M STONY PLAIN REGION GEOHAZARD RISK ASSESSMENT SITE INSPECTION FORM HIGHWAY AND KM: Hwy 621:02, km NAD 83 COORDINATES: E, N PREVIOUS INSPECTION DATE: June 17, 2008 RISK ASSESSMENT: PF: 9 CF: 7 TOTAL: 63 INSPECTION DATE: June 2, 2009 SUMMARY OF SITE INSTRUMENTATION: Slope Inclinometers: 2 Pneumatic Piezometers: 2 INSPECTED BY: Adam Gmeinweser, P. Eng. (EBA) Chris Gräpel, P. Eng. (EBA) Roger Skirrow, P. Eng. (TRANS) Sabhago Oad, P. Eng. (TRANS) Neil Kjelland, P. Eng. (TRANS) Rocky Wang, P. Eng. (TRANS) LAST READING DATE: May 20, 2009 PRIMARY SITE ISSUE: Lateral deformation/rotation of east bridge abutment. APPROIMATE DIMENSIONS: 9 m below headslope. DATE OF REMEDIAL ACTION: None yet, structural evaluation by CH2M Hill completed ITEM CONDITION EISTS DESCRIPTION AND LOCATION NOTICABLE CHANGE FROM LAST INSPECTION YES NO YES NO Pavement Distress Settlement caused by deflection of east bridge abutment. Slope Movement Small scale slope movement of east river bank. Erosion Seepage Culvert Distress Bridge Structure Distress Top of piers rotating to the east. East abutment pushing into bridge deck. COMMENTS: Evidence of crushing failure on concrete retaining wall due to westward lateral shifting of bridge beams. Location and site plan shown on Figure 1. Site conditions shown in Photos 1 to 8. Risk level unchanged from Bridge assessment report conducted and completed by CH2M Hill.

2 STONY PLAIN REGION GEOHAZARD RISK ASSESSMENT SITE INSPECTION FORM SITE OBSERVATIONS: Instrumentation data from slope indicator SI-02 indicates that the depth of the movements is approximately 19 m beneath the pavement or approximately 13 m below river level. Artesian conditions exist within the bedrock on both sides of the river. Top of east pier rotating to the east. A crack is present at the top of the pier; this is relatively unchanged since East abutment is pushing into east abutment. The south wing wall on the east abutment has deflected outward which has caused settlement of the road surface and lateral deflection of the bridge guardrail. Transverse cracks are present to the east of the bridge and this cracking appears to match up with a scarp feature present to the south of the highway in the turn out area on the east side of the bridge. The lateral and rotational movement of the abutment structure appears to have caused the beams to be shifted to the west. Movement appears to have caused bridge beam to have moved over bearing plates on both abutments. The beams are in contact with the east retaining wall which has caused some crushing failure of the concrete at the contact. The shifting of the beams appears to have continued across both piers as indicated by the apparent lateral deflection of the beams on the west bearing plates. The east and west piers appear to have rotated slightly based on visual inspection. The erosion failure repaired in June 2008 is in relatively good condition. Some vegetation has been eroded and plastic netting from the rolled erosion control product is visible. RECOMMENDATIONS: Review completed bridge inspection report submitted to the Bridge department. Recommendations for geotechnical assessment from report should be implemented. Two additional slope inclinometers and piezometers should be installed to assess the movement at the east bridge abutment and the toe of the east head slope. TRANS should assess the environmental liability of artesian groundwater flow located at SI-01; depending on the environmental liability study outcome, SI-01 should be decommissioned to halt artesian flow A topographic survey of the area should be conducted, including the bridge deck and abutments, head slope and approach fill geometry. Existing LiDAR data may be used for the topographic survey. River bed bathymetry should also be surveyed. A hydrotechnical assessment should be conducted based on the inundation of the bridge deck during at least one past flood event. Replacement of the bridge and head slopes is recommended for the future with detailed geotechnical investigation and design.

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4 Photo 1 Deflection of guardrail posts at east abutment Photo 2 South side of bridge, looking west

5 Photo 3 East bridge pier; note rotation of pier; arrow indicates cracking at pier cap Photo 4 Repaired erosion failure on south side of east headslope

6 Photo 5 Diagonal cracking on east abutment Photo 6 Displacement of bridge beam on bearing plate at east abutment

7 Photo 7 Displacement of bridge beam on bearing plate at west abutment Photo 8 View of north side of bridge, looking east; note small slide feature at base of slope adjacent to headslope