9.3. SR 08-15-1994 - Laserfiche WebLink

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. Mr. Phil Hals August 8, 1994 Page Two wall. There is a stairwell entrance into the cinema building at the southeast comer of the basement and a rented garage area at the southwest comer, and there may be other unknown open or voided spaces behind this wall. The proposed backfill materials in these locations could create an unstable and overstressed wall condition. The existing wall and footings do not appear structurally adequate/stable to restrain outward lateral earth pressures without any inward lateral restraint. The City has no as-built record of the design and construction of the south wall and footing for the abandoned basement and adjacent cinema building walls. Without this information, a thorough structural evaluation and rating cannot be performed. Also, without correct footing size and construction information, the overall wall stability will be unknown. To assure that the earth backfill does not impair the existing basement and cinema building walls, the outward lateral earth forces must be minimized. . The most cost-effective and maintenance-free method would be to stabilize the backfill material with the proper fill slope away from the existing wall. A slope angle of approximately 45 degrees for well compacted granular material would be required for slope stability. The wedged area between the sloped backfill and wall face should be filled with an engineered concrete fill. The concrete fill should be placed in 2-foot maximum lifts. There are a few concrete fill materials that would work well for this application, two of them being Elastizell EF Class II and K-Crete. Both concrete products can be supplied with a 50 psi compressive strength. Elastizell EP Class II is lighter weight than K-Crete, more self- compacting, and less difficult to contour to the desired slopes. The cost for Elastizell EF Class II is more expensive than K-Crete. Elastizell will cost around $60 per cubic yard and K-Crete will cost approximately $40 to $45 per cubic yard. Because the vertical height of the concrete fill is not critical and the proposed ground slope is relatively gradual, K-Crete fill would be most practical for the City to use. I estimate the cost to furnish and install the K-Crete for this project in the range of $5,000 to $10,000, depending on the orientation of the patio area. Please reference the attached proposed concrete fill placement details. If you have any questions, please feel free to call. Sincerely, 0~~~S David L. Conkel, P.E. . DLC:tw Attachments 230100o-0504.aug