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Home My WebLink AboutCOM2010-00077 Foundation Fire Assessment - COM Engineering / Geo-Tech Reports - 12/4/2009 James W. Ashley-Cole, P.E. CONSULTING ENGINEER Limited Visual Observation For Bradley Scott, Inc. Blue Heron Resort & Condominium Engineering Services/ Foundation Fire Assessment East 6520 Hwy 106 Union WA 98952 Project No. 2009.128 December 4, 2009 The information contained in this report has been prepared exclusively for Bradley Scott,Inc.The Engineer of Record assumes no responsibility or liability for any use of this report by other parties. The conclusions are based on limited visual observations made at the site.Destructive testing or monitoring was not performed or requested.This submittal has not included an engineering analysis to load rate(Performing an analysis to compare the existing structural capacity with the current Building Code)any aspect of the building. Within the limitations of scope,schedule and budget,this service has been executed in accordance with generally accepted practices in this area at the time this report was prepared.No warranty,express or implied, should be understood. 1 James W. Ashley-Cole, P.E. CONSULTING ENGINEER December 4,2009 Bradley Scott,Inc. Arm, Bob Macbt 400 Warren Ave. Suite 450 Bremerton, WA 98337-1408 Tel:(800)479-6900 RE: Blue Heron Resort& Condominium Recreation Center Engineering Services/Foundation Fire Assessment East 6520 Hwy 106,Union WA 98952 Project No.2009.128 Dear Bob, At the request of the Blue Heron Resort Site Manager(David Brandtt: 360.898.3123)a limited visual observation of the Recreation Center foundation was performed on Thursday December 3,2009. This service has been performed in accordance with the December 2. 2009 Engineering Services Agreement. The super structure of the club house was destroyed in the fire that occurred on September 1,2009.The removal of the fire debris was completed on December 2. The scope of this observation has been luuited to the following: • Perform a site trip to observe the existing foundation. • Prepare an engineering opinion report discussing the following: i)- Observe pre-existing geometry and condition of the foundation. ii)- Document the effect of the fire on the foundation. iii)-Present an opinion of the suitability to reuse the foundation into the reconstruction of the building. No other aspect of this existing building has been addressed. Non-structural systems in the building such as plumbing or on site storm water collection have not been addressed. Every effort has been made to perform a professional assessment. However, there may be other deficiencies in the building such as inadequate perimeter insulation, under slab vapor retarder, capillary break,poorly compacted sub grade or improper site drainage. Introduction The Recreation Center was a single story stick framed building with dimensional lumber roof rafters and beams used to support the vaulted hip roof(Reference Photo 1). The walls were constructed of 2 x studs that were supported by the floor slab bearing on the perimeter foundation. The perimeter foundation is a 6 inch wide by 4' tall retaining wall supported by a footing with the approximate dimensions of 8 inch by 1' -6"wide(Reference Photo 2). The perimeter bearing walls were installed just inside the perimeter retaining wall. The soul plates for the perimeter walls and interior partitions are recessed into the floor slab. (Reference Photos 3&4). Flashing was installed between the wood wall and the top of the 2 James W Ashley-Cale, PE CONSULTING ENGINEER perimeter retaining wall. The wood walls had been removed prior to this observation. For this reason the condition of the studs and wall sheathing could not be observed. The Site Manager indicated water intrusion through the base of the retaining wail was a frequent occurrence during wet weather. There is a high potential that portions of the base of the wood walls may have been compromised by degradation due to dry rot or wood pests. The period of construction of the Recreation Center predates building permits or second party inspections of the completed construction. For this reason the construction of the retaining wall,footing and floor slab are not likely to be in compliance with current minimum Building Code requirements. The water intrusion that has occurred through the base of the wall is an indication that a foundation drain is not present around the perimeter of the building. The back of the retaining wall was exposed at several locations after the fire to access buried utilities. There is no asphtic emulsion on the back of the wall. Portions of the floor slab were exposed. There is no vapor retarder or capillary break below the floor slab. There are no anchor bolts present between the base of the walls and the supporting slab. Vertical shrinkage cracks are present at several locations around the perimeter of the retaining wall. Diagonal settlement cracks are present at several locations around the perimeter of the retaining wall (Reference Photos 5&6). These cracks are an indication the retaining wall is under reinforced with horizontal rebar that is typically installed to control shrinkage. The presence or quantity of vertical reinforcing to resist the lateral earth surcharge of the retaining wall is not known. This reinforcing is likely to be a No. 4 Grade 40 bar at a spacing of 36 to 48 inches as was common for non-permitted construction of this vintage. Reference Appendix A for a schematic map of crack locations. Observed Fire Damage The Site Manager indicated the fire started in the men's sauna. The retaining wall at this location has experienced high heat. The heat caused rapid expansion in the concrete. This rapid expansion has induced minor crazing or alligator cracks to form on the interior face of the wall. The extent of this damage is limited to approximately 8 to 10 lineal feet of wall. In my opinion the minor crazing induced by the fire has not significantly damaged the concrete retaining wall(Reference Photo 7). If the crazing had occurred on the weather side of the wall the cracks would have the potential widen and spat] with the effects of water intrusion and freezing expansion. The excavator used for debris removal chipped the top of the wall in several locations. There are other deficiencies present in the wall and footing that are more of a concern than the fire damage or minor chipping observed. Limited Engineering Analysis A limited engineering analysis has been performed on the retaining wall and footing (Reference Appendix A). This limited analysis included the lateral surcharge of the soil and the weight of the building supported by the footing. This analysis has indicated the Recreation Center perimeter footings are over stressed for the applied loads. The following load cases were considered: 3 James W Ashley-Cole, PE CONSULTING ENGINEER Case 1: Lateral Soil and Building Dead Load • Factor of Safety against overturning= 1.38 Less than 1.5 required by code, • Bearing Pressure=2684 PSF, 180%Greater than 1500 PSF Allowable. Case 2: Lateral Soil and Building Dead Load& Snow Load • Factor of Safety against overturning= 1.51 • Bearing Pressure=2288 PSF, 153 %Greater than 1500 PSF Allowable. It is counterintuitive but the higher load placed on the wall has counterbalanced the overturning due to the lateral earth pressure reducing the bearing pressure and increasing the factor of safety. Retaining wall design is as much an art as a science. The engineering community has long relied on a standard for minimum design parameters. This standard in the Concrete Reinforcing Steel Institute (CRSI) Handbook. A comparison of the actual retaining wall footing verses the CRSI minimum recommended standard has been presented in Appendix A. As a comparison the actual footing depth is 0.66 of the recommended depth. The actual footing width is 0.72 of the recommended width. The actual wall thickness is 0.75 of the recommended thickness. The vertical wall reinforcing is 0.50 for Grade 60 or 0.33 for Grade 40 reinforcing as compared to the CRSI recommended minimum wall reinforcing. Older existing buildings are evaluated by comparison with current design requirements. It is common to find some level of over stress in older buildings. The acceptable level for overstress in an existing building is limited to 150 % as compared to current design requirements (Building Code for the Abatement of Hazardous Structures). As indicated in the limited analysis above the foundation bearing pressures exceed the allowable bearing pressures, the factor of safety against over turning is less than 1.5 and the reinforcing and geometric proportions of the retaining wall are significantly less than recommended by the CRSI standards. Other Deficiencies Other deficiencies are present in the foundation of the Recreation Center. • Vertical and diagonal shrinkage and settlement cracks are present that require repair with epoxy injection. • Roof beams supporting the rafters at the ridge and hips were supported by posts. These posts were in turn supported by the interior floor slab. There is no indication the slabs were thickened or footings are present below the slabs to reduce the bearing pressure at these locations. • The original HVAC ducts, plumbing and electrical systems are run below the slab on grade. These systems are old and outdated, in poor condition and likely contaminated and damaged by the fire suppression efforts. Replacement will require extensive saw cutting and demolition of the floor slab. Replacement of these systems will likely be more cost effective than repair. • The Recreation Center is accessed by stairs and ramps that do not comply with current ADA requirements. Improvements to accessibility to stairs, ramps and toilet rooms should be considered. • The original building does not appear to have been properly designed for lateral forces to resist wind 4 James W. Ashley-Cole, P.E. CONSULTING ENGINEER and lateral loading. This is indicated by the lack anchor bolts in the foundation. • The local Building Official may require storm water collection and retention enhancements based on the 2005 Drainage manual(Volume 1,pages 210 R 211). This will be based on one of the following (3)-criteria: 1. 5000 SF of new and replaced impervious surfaces. 2. Building improvements exceed 25 %of the assessed value. 3. Building improvements exceed$500,000. Recommendation In my opinion the foundation and slab of the Recreation Center should be replaced. The preparation of an opinion of probable construction costs exceeds the scope of services authorized. There is a high probability repair and strengthening of the slab and foundation would likely meet or exceed the cost of replacement. An Architect and Engineer should meet with the Mason County Building Officials for a pre-submission conference prior to proceeding with the preparation of repair/replacement documents. Upon completion these documents should be reviewed by a qualified estimator to obtain a reliable opinion of probable construction costs. Conclusion In my opinion it may be more prudent to demolish the existing retaining wall and concrete slab of the Recreation Center in preparation for the construction of a light timber replacement structure. Thank you for this opportunity to be of service to you and Bradley Scott, hlc. Please feel free to call if I can be of any further assistance in this matter. Sincerely. James W. Ashley-Cole,P.E. ASH4 q ; 47 5 I James W. Ashley-Cole, P. E. CONSULTING ENGINEER Appendix A For Bradley Scott, Inc. Blue Heron Resort & Condominium Engineering Services/ Foundation Fire Assessment East 6520 Hwy 106 Union WA 98952 Project No. 2009.128 December 4,2009 Extent of Analysis: The engineering calculations included with this submittal have been prepared exclusively for the above referenced project. The scope of this submittal is limited to the analysis of the retaining wall and footing supporting the now demolished Recreation Center. • Non-structural building systems, including: moisture protection, finishes, paints and coatings are not the responsibility of the Engineer of Record. Design Criteria: Roof: 25 PSF, I= 1.0 Seismic: Sds(Seismic Design Category D)=0.8334,R=6.5,I= 1.0 Wind: 85 MPH,Exposure C,I= 1.0 1800 Cooper Point Rd. SW Bldg.10 Olympia, WA 98502 Tel (360)709-0807 DEC-3-2009 03:43P FROM: TO:13607548896 P.1 I �t7 ` r _III I _ - t I _ 4' Q James W. Ashley-Cole, PE. i CONSULTING ENGINEER UAI OF I SHE OF l i t I - ( - -fd. '- II r - - i rlr r _ I . I j1 i j r RC2JECT I�[U James W. Ash, /e y Bole, P.E. ON LTlNG ENGINEER T _ - - -- I SHEET O I I I Iocj. /.' --�-I 404 7- d - Iz, IZ� i PS x/ L : i ! PRO ac - James W Ashley Cole, P.E. j r CONSULTING ENGINEHER j I sir o i ► j � zr- 77 i E 1 i ! - _-_i� i James W. Ashley-Cole, P.E. I _ i ? 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