1. PROJECT BACKGROUND. June 25, Alberta Transportation Central Region #401, Street Red Deer, Alberta T4N 6K8

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1 Alberta Transportation Central Region #401, Street Red Deer, Alberta T4N 6K8 June 25, 2001 Mr. Melvin Mayfield, P.Eng. Construction Services Coordinator Dear Mr. Mayfield: Central Region Landslide Assessment Site C20 SH771:02 Pavement Distress 2001 Annual Inspection Report Alberta Transportation has initiated a process of risk management at site-specific slope movement sites that includes a 3-ring binder document control system. This Annual Inspection report forms Section B of the document control system for the above site. The annual site inspection was undertaken on June 12, 2001 by Mr. Darren Ratcliffe, P.Eng., of Klohn Crippen Consultants Ltd. Mr. Ratcliffe was accompanied by Mr. Melvin Mayfield, P.Eng., and Mr. Fred Cheng, P.Eng., of Alberta Transportation. This report was prepared by Klohn Crippen Consultants Ltd. for Alberta Transportation Central Region under Contract No. CE053/ PROJECT BACKGROUND Following a recent site inspection on SH771:04 with Alberta Transportation and Lacombe County, an area of distressed pavement was noted. At the intersection of SH771:02 with the township road 41-0, about 2 km north of H20, standing water is present in the ditches and the pavement is beginning to fail due to the water and corresponding softening of the road base. The site plan is shown on Figure 1 and illustrated in the attached photographs. PA L- C20 Annual Report

2 ALBERTA TRANSPORTATION CENTRAL REGION June 25, 2001 Landslide Site C20 Annual Inspection Report 2. SITE OBSERVATIONS Highway 771:02 runs on a north-south alignment. The surrounding terrain is very flat, but there is a slight fall in grade to the west. As shown on Figure 1, the drainage for the site is northward along the east ditch on the south side of Twp Rd 41-0 and then westward through a 0.9 m diameter CSP culvert under SH771 and then westward, south of Twp Rd Some flow continues northwards on the east side of SH771 and passes under the local road through a 0.6 m diameter CSP culvert. Significant areas of standing water were observed in the east ditch of SH771. A small dam in the ditch was contributing to the ponded water, although it is expected that the regional groundwater table is relatively high. The ditch on the west side of SH771 was dry. Numerous cracks and depressions were observed in the pavement over a length of about 150 m. The distress in the pavement generally corresponded with the standing water in the ditches. 3. SITE ASSESSMENT It is considered that the poor drainage in the area has contributed to the softening and distress of the highway structure. There is likely also some damage as a result of frost action. Based on the risk level criteria provided by Alberta Transportation, a risk rating of 9 has been assigned to this site. This is based on a probability factor of 9 for an active feature, and a consequence factor of 1 as closure of the highway is unlikely. 4. RECOMMENDATIONS The following recommendations are provided: A survey of the area should be undertaken to determine the relative ditch grades, etc. The survey would encompass an approximate area of 200 m by 20 m. Using the survey data, a design would be developed to lower the ditch grade to provide positive drainage to the west. As part of the work, the 0.9 m diameter culvert under SH771 will likely have to be lowered. PA L- C20 Annual Report Page 2

3 ALBERTA TRANSPORTATION CENTRAL REGION June 25, 2001 Landslide Site C20 Annual Inspection Report Following the ditch remediation work, the highway should be repaved. An estimated cost for the survey and design work is about $6,000 to $7,000. A cost estimate for the construction work would be provided at this time. Please contact the undersigned if you have any questions regarding this report. Yours truly, KLOHN CRIPPEN CONSULTANTS LTD. Darren Ratcliffe, P.Eng. Senior Geotechnical Engineer Brian Rogers, P.Eng. Manager, Alberta PA L- C20 Annual Report Page 3

4 ALBERTA TRANSPORTATION CENTRAL REGION Landslide Site C20 Annual Inspection Report FIGURE PA L- C20 Annual Report

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9 Looking south (note standing water in east ditch) Looking north from previous location Page 5 of 14

10 Looking north west side Looking north east side Page 6 of 14

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12 Water in east ditch following towards the cross culvert Page 8 of 14

13 0.9 m diameter culvert inlet on east side of highway Page 9 of 14

14 Culvert outlet on west side of highway. Note crack and heaving of pavement over pipe. Page 10 of 14

15 Depressions in pavement at intersection with Twp Rd 41-0 Page 11 of 14

16 Depressions in pavement at intersection with Twp Rd 41-0 Page 12 of 14

17 Depressions in pavement at north end of site (note test core holes) Culvert under Twp Rd 41-0 north end Page 13 of 14

18 Page 14 of 14