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Eagan Gardens - 2007-12-27 Ltr Walk Through Letter for Parking Facility , IlD , yr3 � l2��� 2 � � Walker Restoration Consultants WALKER 1660 S.Highway 100,Suite 350 �esroxanoN cor�su�Ta,Nrs Minneapolis,MN 55416 Voice: 952.595.91 16 Fax: 952.595.9518 www.walkerrestoration.com December 27, 2007 Mr. Bill Hauge Condominium Manager 2100 Summer Street, N.E. Suite 280 Minneapolis, MN 55413 Re: Walk Through Letter Report for Eagan Gardens Parking Faciliiy Eagan, Minnesota Walker Commission No. 21-3485.00 Dear Mr. Hauge: The purpose of this walk through review of the parking facility is to concentrate on structural deterioration and structural concerns requiring safety/immediate repairs. We understand that Eagan Gardens has been requested, by the City of Eagan, to have a structural engineer perform an Evaluation Report of Findings of the parking facility byJanuary 1, 2008. Also, the City requires a Proposed Plan of Action for repairs, which will not be part of this report. EXECUTIVE SUMMARY We did observe significant corrosion induced concrete deterioration to the stair landing at the northwest stairwell that, in our opinion, should be shored immediately and repaired in spring of 2008. Also, we recommend installing a shore under the stair landing at the northeast stairwell to supplement the unanchored timber post. The remainder of the parking structure is in generally fair , condition with no structural deterioration, deficiencies or safety related issues that would limit the structure to its intended use of parking passenger vehicles. FACILITY DESCRIPTION Constructed in the 1970's, the parking facility consists of one supported level (approximately 128 feet wide by 356 feet long) and an on-grade level. The structural system for the supported level is precast double tees 8 feet wide by about 64 feet long supported by concrete masonry unit at the north and south sides, and precast inverted tee beams and precast columns along the center column line. An expansion joint (in the north/south direction) is located at the midpoint of the long direction. The facility is two parking bays wide with one-way traffic and straight in parking. The entrance/exit to the supported level is located at the northwest corner and the southwest corner to the on-grade level. The facility has four stair wells. The stairs and landings are constructed of conventionally reinforced, cast- in-place concrete and enclosed with fluted block walls. :.�. V1/ALKER M�. B� Hauge aesTORar�oN coNsu�r,aNrs December 27, 2007 Page 2 VISUAL OBSERYATION SUMMARY AND CONCLUSIONS During the course of our visual observation of this parking facility, we did observe one condition, northwest stairwell landing, which in our opinion, has considerable corrosion induced deterioration and requires immediate shoring. Limited overhead concrete deterioration requires removals to reduce the hazard of falling concrete are recommended. However, hidden or latent conditions may exist in this facility, which have not yet revealed themselves through visual evidence and may require subsequent removal. The following is a summary of conditions noted: 1 . Significant corrosion induced concrete deterioration, delamination and lift off was observed to the concrete stair landing at the northwest stairwelL 2. A 4 inch by 4 inch timber s�pport post is used to support the stairwell landing and is located at the northeast stairwell. The timber does not appear to be anchored to the slab or the block wall which it bears. Wood should not be used for permanent structural support. 3. Horizontal movement (bowing) of the block retaining walls were noted at all of the stairwells. 4. Shear cracks in block walls were observed at the bearing areas for the stairwell landings. Cracks appear to be due to differential movement between the parking structure and the stairwell resulting from the lack of a slide bearing for the landing slab. 5. Cracks in block and mortar joints were noted at stairwells and isolated locations in the bumper walls. 6. Previous repairs to the bumper wall along the south half of the west wall included installation of steel tie rods anchoring the wall to the adjacent double tee stem. 7. Isolated and small (1/2 square foot or less) floor delaminations were noted in the supported level slab primarily located at double tee shear connectors. 8. Previous floor spalls/delaminations at the double tee shear connectors were sealed with joint sealant materiaL 9. Large areas (100 to 200 square feet) of moderate to severe scaling (freeze/thaw deterioration) of the supported driving surface (top of double tees) were noted at isolated locations. lO.Visual observations from the top side indicated isolated adhesive and cohesive joint sealant failures at the tee to tee joints. Visual observations from the underside of the upper level indicated leaking of tee to tee joints throughout. Most leaks were b inches or less with isolated leaks up to 10 foot in length. 1 l .lsolated and small (1/4 square foot or less) tee flange spalls/delaminations were noted and located at leaking or previously leaking tee to tee joints 12.Isolated inverted beam delaminations were observed. 13.Worn traffic topping, located at the inverted tees at the upper level end crossovers,was noted. Leaking was noted below. 14.Floor cracks were noted throughout and primarily located at the end of the double tees and parallel the tee stem below. This is common and occurred during removal of the double tee from the formwork. Many of these cracks have been previously routed and sealed. 15.Miscellaneous lights were noted not functioning. 1 b.Expansion joints were observed leaking. WALKER M�. Bill Ha�ge eEsroekTioN coNsu�raNls December 27, 2007 Page 3 Leaking tee to tee joints, expansion joints, or cracks can contribute to corrosion of embedded reinforcing steel in the double tees, inverted tee beams, and columns. Based on our observations, the structure is capabfe of supporting the loads for which it is used. This structure is primarily used for parking of passenger vehicles and, in our opinion, presently is capable of supporting that load. However, we recommend immediate shoring of the stair landing at the northwest stairwell, install a supplemental post shore under the stair landing at the northeast stairwell and remove all loose overhead concrete and continue, as it is detected. Further recommendations include repair/replacement of the stairs and landing at the northwest stairwell and replacement of the timber post with an anchored steel post at the northeast stairwell in 2008. We recommend repair of all remaining items above in the next 2 to 3 years. It should be noted that Walker Restoration Consultants has not performed a structural review to verify the structural adequacy of the original design, as this is not within the scope of work. During our review, we did not observe deterioration to be indicative of inadequate original structural design or construction. If we can be of further assistance or answer any questions, please call on us. Sincerely, WALKER RESTORATION CONSULTANTS ,�==���-. C� Richard J. Elsner, P.E. Senior Restoration Engineer