B09_A1_Attach_14c_Ahwahnee_HSR_Final_Submittal_-_Report_0001.pdf

Architectural Assessment: InteriorsARCHITECTURAL RESOURCES GROUP

Histor ic Structures Report

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January 2011

Employee Locker Rooms

Floor, Walls, and Ceiling Th e fl oors are in fair condition. Th e concrete is in good condition, but the painted fi nishes are worn away in areas that receive heavy traffi c. Th e condition of the walls in these rooms range from poor to good. Th e walls in the stair hall to the Women’s Locker Room are in poor condition; cracking and spalling paint and plaster is evident.

Th e walls in the Gift Shop storage area are in fair condition as they exhibit damage from abrasions and impacts. Th e FRP-panelled walls in the men’s room are in fair condition and exhibit deterioration around the sinks and soap dispensers due to water. Th e walls in the remaining rooms are in good condition. Th e ceilings in all the rooms are typically in good condition with isolated areas of peeling paint.

Th ere is cracking in the Gift Shop storage ceiling.

Openings and Doors Th e doors are typically in good condition, although they exhibit wear from heavy use.

Lighting Th e lighting is in good condition.

Special Features Th e toilet partition at the urinal in the men’s toilet room exhibits corrosion at the bottom of the panel. Th e toilet partitions are otherwise in good condition.

Historic Utilitarian

FIRST FLOOR / MEZZANINE

Figure 376: Detail view of wall and fl oor in Men’s Locker Room, 2010. Note deterioration of FRP panels under soap dispensers. (Source: ARG)

Figure 377: Detail view of fl oor in locker area in Women’s Locker Room, 2010. Note worn paint fi nish.

(Source: ARG)

Figure 375: View of partitions in Women’s Locker Room toilet room, 2010. (Source: ARG)

ARCHITECTURAL RESOURCES GROUPArchitectural Assessment: Interiors

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January 2011

Basement

Floor, Walls, and Ceiling Th e concrete fl oors are unpainted and in fair condition. Th e Boiler Room fl oods seasonally from ground water, which is accelerating the deterioration of the concrete. Th e walls in the Basement are generally in poor condition with dislocated gypsum blocks and spalling cement plaster and concrete. Th e exposed concrete ceilings are also in poor condition; they exhibit spalling and exposure of reinforcing bars.

Openings and Doors Th e doors and hardware are typically in fair condition in the Basement. Th e doors are typically deteriorated at the base due to fl ooding in the Basement. In some cases, the metal cladding on the wood doors has separated from the door, allowing water to penetrate to the wood surface below. Th e metal cladding also shows signs of corrosion.

Special Features Although the dumbwaiter shaft is blocked, the dumbwaiter box appears to be in good condition.

Historic Utilitarian

Figure 378: View of Basement walls and ceiling, 2010. Note spalling and exposed reinforcing bars.

(Source: ARG)

Figure 379: Detail view of deterioration at wall and door in Basement, 2010. (Source: ARG)

Figure 380: Detail view of wall and ceiling in Basement, 2010. (Source: ARG)

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January 2011

Elevator Penthouse

Floor, Walls, and Ceiling Th e fl ooring is painted wood fi ber board and it is in poor condition with deeply worn areas. Th e painted concrete fl oor is in good condition. Th e Acoustex planks that clad the sloping walls and ceiling appear to be intact and in good condition.

Openings and Doors Th e hinged wood panel at the entry to the Elevator Penthouse is in poor condition due to heavy use.

Special Features Exposed steel beams in this space are in good condition.

Historic Utilitarian

Figure 381: Detail view of ceiling in Elevator Penthouse, 2010. (Source: ARG)

Figure 382: Detail view of access hatch to Elevator Penthouse, 2010. (Source: ARG)

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January 2011

Maintenance Shops

Floor, Walls, and Ceiling Th e fl ooring in the Maintenance Shops, which includes wood and plywood decking, is in fair condition. Th e fl ooring surfaces are worn from heavy use. Th e gypsum board and wood walls and ceilings are also in fair but serviceable condition.

Openings and Doors Th e wood doors are in fair condition with scrapes, staining, and weathering evident. Th ey are operational but are not designed to maintain a weathertight condition.

Special Features Th e fl uorescent strip fi xtures are in good condition.

Non-Historic

Figure 383: Detail view of corbels in Maintenance Shops, 2009. (Source: ARG)

Figure 384: View of post and beam construction at exterior wall of Maintenance Shops, 2009.

(Source: ARG)

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January 2011

T H E A H WA H N E E

C OT TAG E S

Floors Th e carpet that covers the original wood fl oors in the Cottage bedrooms and the hexagonal tile fl oors in the bathrooms are in good condition, both having been installed within the last few years.

Deterioration of the tile fl oor fi nishes is typically limited to soiling at the grout between tiles and cracks at the bathroom thresholds.

Walls Most of the walls of painted gypsum board in the Cottages are in good condition, although narrow cracks at the corners of windows and doors are common. Th e vertical wood paneling typically found between bedrooms and bathrooms is also in good condition, although the degradation of the stain fi nish is visible in areas of heavy use. In addition, the lower portion of the walls and the wood base trim elsewhere in the Cottages are gouged and scratched from movement of furniture and the use of luggage carts. Th e recently installed tile wainscot at the bathrooms is in very good condition.

Th e original wall stenciling at the tops of the walls in most of the Cottage guest rooms is in fair condition. Soiling is common at most of the stenciled areas. In addition, the repainting of the walls in several rooms has encroached on the stenciled areas. In rooms 709, 712 and 715, the lower portions of the stencil patterns have been overpainted, which has created an erratic edge to the stencil pattern.

Th e historic wood panel friezes located in rooms 723 and 721 are in good condition.

Ceilings Th e ceilings of painted gypsum board are in good condition, although they typically exhibit hairline cracks at ceiling/wall junctures and between ceiling boards. Th e gypsum board that lines the pitched ceilings of the two former living room areas (now Rooms 714 and

719) is also in good condition. Hairline cracks are not evident, but gaps between the gypsum-board ceiling and the exposed ceiling beams are common.

Openings and Doors Th e interior wood doors are generally in good condition, although the stained vertical plank doors in the bedrooms have signifi cant fi nish damage to the doors and frames. Th e wrought-iron hinges at these doors are in good condition, but other door hardware is only in fair condition. Th e knobs and levers located upon the vertical plank bedroom doors are oft en so loose as to be inoperable. Th e hinges at the bathroom doors are typically rusted.

Lighting Th e light fi xtures in the bedrooms, dressing rooms and bathrooms of the Cottages are in good condition.

Special Features Th e Cottage fi replaces located in each of the living rooms of the central units in the fi ve-plex Cottages. Th ey have heavy accumulations of soot. Th e stone fi replace surrounds also show signs of soot that detract from their appearance, but otherwise they are in good condition.

Some of the wall heaters have damaged grilles and are generally in poor condition. A few of the heaters appear to be relatively new, and they are in good condition. Recently installed wall-mounted air conditioners are in good condition.

Signifi cant (Living Rooms) Contributing

Figure 385: Detail views of overpainted stenciling in Cottage rooms 709 and 715, 2010. (Source: ARG)

Figure 386: Newly remodeled Cottage bathroom, 2009. (Source: ARG)

Figure 387: Typical strap hinge at doors between bedrooms and dressing rooms in Cottage, 2009.

(Source: ARG)

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January 2011

C O OK S AND SU PPLY

BU I L DI NG

( E M P L OY E E D OR M I TORY )

Floor, Walls, and Ceiling Th e carpet covering the fl oors of the employee rooms, hallway and the community room is in fair condition; it exhibits staining and areas of it are worn. Th e painted plywood fl oor in the offi ce is in fair condition with areas of peeling paint. Th e residential-grade vinyl fl ooring in the bathrooms, shower rooms, and laundry rooms is in fair condition; it has small stains and cracks on its surface.

Th e plywood walls and wood trim are all in fair condition. Small holes are evident in the wall panels where residents added screws and nails to hang things. In select locations, the battens are separating from the walls, and there is mildew and mold on the walls in a few of the employee rooms. Th e base trim has small nicks and gouges in its surface due to heavy use.

Like the walls, the plywood ceiling is in fair condition. Some of the plywood panels are bowing and sagging.

Openings and Doors Th e wood doors are generally in fair condition with scrapes, dings and holes remaining from items previously mounted on the doors.

Th e wood door frames have some damage in isolated areas. A few of the doors have damage to the frame where they appear to have been previously opened with force. Th e door knobs and locks are in good condition; the hinges, strikes and other pieces of hardware are generally in fair condition due to their heavy use.

Non-Historic

Figure 388: Detail view of damage on door frame in Employee Dormitory, 2010. (Source: ARG)

Figure 389: Detail view of fl oor in Employee Dormitory offi ce, 2010. (Source: ARG)

Figure 390: Detail view of carpet wear and staining in Employee Dormitory, 2010. (Source: ARG)

Figure 391: Detail view of crack in vinyl fl ooring in Employee Dormitory shower room, 2010. (Source: ARG)

Structural AssessmentARCHITECTURAL RESOURCES GROUP

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January 2011

STRUCTURAL ASSESSMENT

Introduction Th is section presents the fi ndings of a structural evaluation of Th e Ahwahnee, the adjacent one-story Cottages and the Employee Dormitory on Th e Ahwahnee site. Th is study has been performed by Degenkolb Engineers. In accordance with the scope of work by Delaware North Company/National Park Service, the following assessment contains information regarding the documentation review, structural description, and structural condition survey of the hotel, Cottages and Employee Dormitory made during site visits on 1 June and 23 July 2009.

A document review was performed on all available materials.

No structural drawings were available for review, although some structural information is shown on the original architectural drawings that are available. All evaluations regarding such items as concrete reinforcement, interior framing and connection details are based on limited information shown on the architectural drawings and observations made during the site visit. Each of the structures were photographed for documentation and future reference.

BU I L DI NG DE S C R I P T ION S

The Ahwahnee Main Building Th e Ahwahnee was constructed from drawings prepared in 1926 by Gilbert Stanley Underwood, Architect. Th e General Contractor for the building was James L. McLaughlin whose fi rm of the same name was based in San Francisco. Th e structure is comprised of a steel frame encased in concrete with additional sections of concrete wall around the exterior of the structure.

Th e building is irregular in plan and elevation. Th e general plan of the hotel consists of a central core with west, south and east wings. Th e central core of the structure extends to a height of approximately 100 feet above the valley fl oor with a total of seven stories and an Elevator Penthouse. Th e west wing contains a single-story Dining Room and

Kitchen; the south wing has three stories of guest rooms over the fi rst-story Great Lounge; and the east wing consists of three stories of guest rooms over the Registration Lobby and Ahwahnee Bar. Th ere is a single, small Boiler Room and Basement below the central portion of the structure. Th e west wing contains both the Dining Room and the Kitchen wing. Th e Dining Room is approximately 140 feet long by 50 feet wide and the attached Kitchen is approximately 110 feet by 90 feet. Th e Dining Room is oriented in a northwest to southeast direction, while the Kitchen extends askew from the Dining Room in a north-south direction. Th e dimensions of the south wing are approximately 140-feet long by 50-feet wide, with a 120-foot by 30-foot cruciform section at the south end of the wing. Th e east wing mirrors the west wing in layout, but is approximately 120 feet by 50 feet in plan.

Th e main structure has a complete steel frame consisting of columns and beams with deep truss girders in select locations where long spans necessitate them. Th e steel frame supports cast-in-place reinforced concrete fl oor slabs and steel fl oor framing. Each steel member is encased in concrete for fi re protection, and in some locations the steel framing is coated with light fi reproofi ng material.

In addition to the steel frame, there are exterior reinforced concrete shear walls in the form of a pier-spandrel system. Th e typical fl oor slab is approximately two-to-three inches thick, and the roof slabs are constructed of two-to three inches-thick concrete slabs. In addition to the support of the structural system, the steel frame supports some extremely heavy architectural features. At most exterior corners of the structure, a typical steel column is encased in heavy interconnected granite stones, with mortar fi lling all voids in and around the stones, creating a massive solid unit at least three feet thick, extending up the height of the structure. “Stand alone” columns in the Dining Room support the roof of the Dining Room; these vary slightly in size but they are approximately six-feet six-inches by seven-feet wide and they extend the full height of the room. Th ese “tubes” are composed of granite stonework and grout.

Th e foundation system is comprised of concrete spread footings, walls and grade beams. Th e size and layout of the foundations are undetermined, but the original architectural drawings indicate that they were intended to be massive in order to support heavy vertical loads. Based on observation of spalling and rust stains in the Boiler Room area, reinforcing is present at least in portions of the concrete foundation system.

According to original architectural drawings, all interior partitions are constructed of terra cotta tile or gypsum block. Interior partition walls extend from the top of the fl oor slab to either the bottom of the steel fl oor framing or underside of suspended plaster ceilings.

Th e covered entrance walkway and detached Porte Cochere are located directly to the north of the east wing. Th ese structures are comprised of timber posts supporting a timber truss roof system.

Both the Porte Cochere and covered entrance walkway have roof structures consisting of slate roofi ng over 1x8 straight-sheathed plank construction. Both of these roofs also have plywood sheathing over the straight sheathing, added when these structures were completely reconstructed in November of 1988. All original timber members, as well as steel connection plates and bolts, were replaced with modern timber and steel plates and bolts. Th e new structures are nearly identical in appearance to the original structures, but the construction methods and materials are modern.

Th e Dining Room is constructed of timber log trusses supporting the slate roofi ng installed over straight wood sheathing on top of log purlins and raft ers. Th e trusses are supported on one end by the concrete shear wall adjacent to the Kitchen and on the other end by two 22-inch diameter logs that serve as columns. Th e west end of the structure has six granite stone columns that are hollow in the center. Th e connection of the Dining Room to the main hotel is made through concrete slabs and steel framing below rooms at the mezzanine and third fl oors. A porch at the fourth fl oor level extends over the angled space between the central core portion of the hotel and the Dining Room wing below.

ARCHITECTURAL RESOURCES GROUPStructural Assessment

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January 2011

The Ahwahnee Cottages Th e Cottages located to the southeast of the main building were constructed from architectural drawings prepared in 1928 by Ted Spencer. Th ere are three types of Cottages in Th e Ahwahnee area: fi ve duplex Cottages, one four-plex Cottage, and two fi ve-plex Cottages with central fi replaces. Each of the duplexes is approximately 20 feet by 50 feet in plan. Th e four-plex has a footprint of approximately 30 feet by 50 feet, and the fi ve-plex has an “H” shaped plan with an approximate footprint of 2400 square feet.

Th e Cottages are constructed of light wood framing. Th e walls consist of 2x4 studs spaced at 16 inches on center with exterior wood sheathing. Th e roofs consist of typical wood framing with 1x straight sheathing and cedar shingles. Th e fi ve-plex Cottages have a raft er and tie-beam roof framing system in addition to the details present in all other Cottages.

All Cottages have concrete perimeter foundations and isolated concrete-pier foundations to their interior. Th e fi ve-plex Cottages appear to have separate concrete foundations for the central chimneys.

Cooks and Supply Building (Employee Dormitory) Th e Employee Dormitory is located to the northwest of Th e Ahwahnee main building. Th is structure is approximately 35-feet wide and 150-feet long. It was built during WWII when the U.S.

Navy took over Th e Ahwahnee. Th e exterior walls are framed with 2x4 studs at 16 inches on center with exterior straight horizontal sheathing. Th ere is a perimeter cripple wall at the base of the structure which is sheathed with 1x straight sheathing or sheets of plywood. At the time of a July 2009 inspection all of the cripple wall sheathing on the south, west and part of the north elevations had been removed for inspection. At the time of this writing, a separate project by Th e Waring Group is underway to investigate and strengthen the foundations and cripple walls of the Employee Dormitory. Interior partitions appear to be 1-inch vertical boards with battens. Th e roof is sheathed with diagonal 1x sheathing and topped with built-up roofi ng shingles. Based on observations, it appears that there are two interior and exterior column lines in the building. Columns are spaced at approximately 30 feet on center longitudinally.

Th e timber framing is supported on isolated concrete spread footings below each of the columns at the interior and exterior column lines.

A three-foot high crawlspace extends below the entire structure.

Th ere were no drawings available for this structure and no record of construction. Th e evaluation, description and recommendations for the Employee Dormitory are made purely on information gathered during the site visit.

V E RT IC A L SYST E M E VA LUAT ION

Based on observations, the gravity load carrying system for each of the buildings described above, except the Employee Dormitory, appear to have performed well under everyday load conditions. Th e buildings and the vertical systems of the hotel and Cottages appear to be in good condition. No visible signs of distress were observed during the limited fi eld investigation.

However, maintenance personnel reported that several areas of the Kitchen fl oor have required repairs recently aft er wheeled maintenance equipment caused fl oor tiles to crack or off set. Th e concrete in these areas had deteriorated considerably with the top inches of the concrete slab essentially reduced to sand and gravel, apparently from years of washing down the Kitchen fl oors each night.

Th e full extent of the deterioration of the Kitchen fl oor is unknown, but its ability to resist full design loads is in question, and eventual replacement of all or portions of this slab will probably be needed.

Th e Employee Dormitory shows considerable signs of distress at the west end of the structure due to diff erential settlement.

Th ere is also obvious distress evident in the fl oor framing where the poor ventilation in the crawlspace of the structure traps high humidity air. A separate study by Th e Waring Group has identifi ed rotting conditions, carpenter ant infestation and numerous signs of foundation distress. Th ey have prepared recommendations to repair and strengthen the foundations of the Employee Dormitory.

At the time of the July 2009 inspection all cripple-wall sheathing for over half the building had been removed and covered with plastic sheathing.

M I S C E L L A N E OU S OB SE RVAT ION S

Th ere is a partial Basement located under the central area of Th e Ahwahnee main building. It contains a Boiler Room, Electrical Room and other services. During the 1 June 2009 visit, ground water was entering at the landing of the exterior access. Additional voids on the slab below the landing were observed. Th ere was also evidence of water entering the Basements at many locations, especially in the Electrical Room where the access may be through a noticeable void beneath the stone column at grade above.

Th e numerous balconies of Th e Ahwahnee have vertical concrete posts and timber railings. Th ere is evidence that many of these vertical concrete posts have been partially repaired in the past.

Some of the repairs are failing, probably due to further corrosion of reinforcement within the post since their previous repair. Further repairs are needed. Th e horizontal wood rails between posts have deteriorated, and many show signs of rot. Water apparently enters the checks and splits of the round logs, and freezing conditions further split the wood, inviting rot. It it understood that replacement of these rotten logs is scheduled. Additionally, loose concrete was observed on a horizontal cantilevered bracket below the fourth fl oor exterior balcony above the Dining Room, which requires repair.

Th ere are many decorative beams ends at the exterior of Th e Ahwahnee. Extensive repairs of these beam ends were made several years ago with good fl ashing details to protect the structural beams.

Th ese appear in good condition except for the few exceptions noted above. Th e original cantilever brackets supporting light fi xtures were replaced in 1977 by details developed by Walter Sontheimer with new steel brackets covered with epoxy resin fi nish. While most of these

Structural AssessmentARCHITECTURAL RESOURCES GROUP

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January 2011 appear in good condition, one located on the east elevation exterior of the Ahwahnee Bar has deteriorated and is in need of repair.

L AT ER A L SYSTEM EVALUATION

Th e Yosemite Valley is located in a relatively low seismic zone in California. Th e soil in the Yosemite Valley is a glacial till type soil with extremely deep alluvial deposits from the many years the valley was a lake following the glacial period. Th e Ahwahnee site may have over 100 feet of loose and compacted sand and silt below the surface soil. Th e soil characteristics of the site appear fi rm and stable. Previous studies have suggested there is a potential for seismic liquefaction and settlement in the soils beneath Th e Ahwahnee.1,2 At the time of this writing, a separate evaluation is currently underway to refi ne the expected ground motion and liquefaction potential at the site.

Due to the continuous development of seismic design standards since the construction of Th e Ahwahnee main building and other structures in Th e Ahwahnee area, none of the buildings evaluated would be expected to conform with current seismic code. However, there are some inherent qualities of the structures that may provide adequate lateral resistance to moderate ground shaking.

None of the buildings observed showed signs of signifi cant distress or degradation of elements that comprise the lateral-force resisting system. Th e Employee Dormitory shows some signs of distress.

Given that all cripple-wall sheathing is currently removed from the south and west perimeter at the time of this writing, the Employee Dormitory is quite vulnerable in this condition. It could partially collapse should an earthquake occur before repairs are completed.

1 URS, Seismic Rehabilitation Alternatives for Th e Ahwahnee Hotel, Yosemite National Park (Report prepared for National Park Service, February 2002).

2 Martin/Martin Consulting Engineers, FEMA 178 / June 1992 Seismic Evaluation Th e Ahwahnee Hotel Yosemite National Park, Mariposa County, California, Final Report August 1999 (Report prepared for the National Park Service Denver Service Center).

Th e lateral-force resisting elements in the hotel and Cottages appear to be well maintained and in good condition.

The Ahwahnee Main Building Th e main portion of Th e Ahwahnee main building, consisting of the east wing, south wing, Kitchen and central area, has a complete lateral system, which consists of a thin concrete slab roof diaphragm, and an exterior reinforced-concrete pier spandrel system that encases a complete steel frame. Floors are typically steel-framed concrete slab diaphragms that span over open-web joists and structural steel beams and columns. Some of the architectural aspects of the structure, such as the exterior stone around its perimeter, may also add to its lateral-load resisting capacity. In turn, these architectural features add a signifi cant amount of weight to the structure, thereby increasing the demands on the lateral-force resisting system.

Th e steel frame appears to have beam-to-column connections of riveted seat angles and top-fl ange or web connections providing seismic, rigid, lateral-load resistance. Th is type of riveted steel frame provides good ductility and continuity and is typical of the steel-frame details that performed well in San Francisco during the 1906 earthquake. Th e presence of the exterior reinforced-concrete piers and spandrels provides stiff ness and energy dissipation at least under moderate seismic loading. Th us, the two systems working in tandem provide the building with a ductile lateral-force resisting system with moderate seismic force resistance.

Th e Dining Room has a wood sheathed roof supported by joists and large timber trusses. Th e trusses are supported along the south by columns constructed of two mated logs. Th ese columns are connected to the trusses and concrete foundations with details that allow rotation at each end of the column. Th is condition will cause very fl exible behavior of this window wall when subjected to moderate lateral loads. Th e interior north wall, common with the Kitchen, appears to be of concrete construction with encased-steel columns (and a decorative timber post) supporting each Dining Room truss. At the west end of the Dining Room, there are six large, hollow stone columns, which defi ne the space of the alcove and west wall. Th ese columns, about six feet 6 inches by seven feet wide, are of stone construction. Th e connections of the timber roof to the tops of these stone columns is uncertain, but it is probably quite nominal.

Th e east end of the Dining Room has four similar stone columns, but these contain a structural-steel column inside to support a portion of the hotel tower above. Th e Kitchen to the north of the Dining Room oriented on a bit of a skewed direction in plan, is steel framed with concrete roof slabs and walls on all four sides.

Th e lateral-force resisting system of the Dining Room is questionable and appears very minimal. Th e straight-sheathed wood roof provides a very weak roof diaphragm and there does not appear to be a strong connection to the roof diaphragm above the Kitchen. Th e stone columns at the west end are unreinforced and have some initial strength as rigid rocking elements, but they lack ductility for eff ectual seismic resistance.

Due to the lack of a detailed lateral-force resisting system in the Dining Room, considerable damage, both structural and non-structural, may occur in this portion of the structure when subjected to moderate ground shaking. Particularly, damage may be expected along the south and west lines of the Dining Room.

Interior partitions appear to be typically a three-inch thick gypsum hollow block (manufactured by U.S. Gypsum Company) with plaster on all fi nished surfaces (not on concealed or in unfi nished spaces).

It is not clear if a metal lath was provided with the plaster. Th ese partitions typically stop at the suspended plaster ceilings, which do contain metal lath. Th e seismic stability of the partitions needs to be established and whether strengthening measures are needed.

Th e Porte Cochere is a wood-framed structure with timber trusses and posts with knee-braced connections. Stone columns provide support at the four corners. Th e timber structure is reasonably stable for lateral forces although the stone columns are rigid and brittle and, in a seismic event, may partially collapse. Th e wood-frame covered entry walkway is of timber construction with knee-braced connections, which should be stable in the type of seismic shaking expected in Yosemite Valley.

ARCHITECTURAL RESOURCES GROUPStructural Assessment

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January 2011

The Ahwahnee Cottages Th e Ahwahnee Cottages are framed with interior and exterior 2x4 stud walls. Th e roof diaphragms are constructed of 4x6 raft ers at 30 inches on center with 2x6 joists spanning between raft ers. Th e roof is sheathed with 1x straight sheathing and are covered with wood shingles. Th e exterior walls are sheathed with 1-inch thick straight sheathing and bear on concrete perimeter footings. Th e architectural drawings show some type of attachment between the sill plate and the concrete perimeter footing, although it is not clear if the wood sill plates are bolted to the concrete foundations. Th e interior stud walls have thin wood sheathing and will resist some lateral load. Th ere does not appear to be chimney bracing present at the fi ve-plex Cottages.

Th e Cottage construction has a complete lateral-force resisting system and is very similar to typical small, light, wood-framed residential units constructed during the 1920s and 1930s. Th ese structures typically perform well in the presence of moderate ground shaking. A few of the Cottages contain a fi replace and chimney in the central room, and as the masonry is more rigid than the wood-framed Cottage, some damage at the wood-masonry connection should be expected in an earthquake. Since the masonry chimney is probably not well connected to the wood construction, it might lean or partially collapse in strong shaking. Th e overall condition of the Cottages appears to be good. Some of the Cottages have received interior upgrades or remodeling, but each structure appears to match the original design. All structural materials in the Cottages seem to be in good condition with no loss to their structural integrity.

Cooks and Supply Building (Dormitory) Th e dormitory is a wood-framed structure and has a complete lateral force-resisting system. Th e roof is framed with 2x6 raft ers and 1x diagonal sheathing topped with a wood-shingle roof. Th e exterior 2x4 stud walls are sheathed with one inch straight sheathing. Th e attic space has at least one plywood-sheathed attic wall extending from the top of the ceiling framing to the bottom of the roof framing.

Below this attic wall, an interior stud partition runs the length of the building along the interior column lines. Some of the interior partition walls are of single-board construction (one-inch vertical boards with battens). Both interior and exterior walls are assumed to comprise the lateral load force resisting system for both longitudinal and transverse directions.

Th e deteriorated conditions of the foundation noted by Th e Waring Group has compromised the lateral-force resistance of the structure.

Th e current condition of the foundation with removed cripple walls and deterioration of the posts and piers results in a very vulnerable structure. It will be susceptible to partial collapse in a seismic event until such time that repairs are made to correct these defi ciencies.

Mechanical Systems AssessmentARCHITECTURAL RESOURCES GROUP

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January 2011

M E C HA N IC A L SYST E M S AS SE S SM E N T

Th is report is an assessment and evaluation of the mechanical systems in Th e Ahwahnee, the Cottages and the Employee Dormitory conducted by Mechanical Design Concepts. Th e mechanical systems include the heating, ventilating and air conditioning (HVAC) systems, plumbing systems and fi re suppression systems.

Site Utilities Th e Ahwahnee is served by the following mechanical utilities:

1. Domestic water - Th ere is a 4 inch loop around Th e Ahwahnee.

A 6” line passes through Th e Ahwahnee (north to south) in the crawl space. Th is 6-inch line is connected to the 4-inch loop at both the north and the south. Th is 6-inch line feeds the fi re sprinklers in Th e Ahwahnee. Th ere is also a 2-inch connection from the 4-inch loop to the east wing. Th e 4-inch loop also extends through the Cottage area. A 4-inch line extends westward to the western edge of the Employee Dormitory. At that point, there is a 2-inch connection to the Employee Dormitory.

Th e 6-inch line in Th e Ahwahnee crawl space was installed in approximately 1990. Th e age of the 4-inch site loop is unknown.

2. Fire suppression water - Th ere is an 8-inch fi re loop around Th e Ahwahnee. Th is loop is fed from a 12-inch line. Th ere are fi re hydrants located to the south and west of Th e Ahwahnee; there are three hydrants in the parking area and two hydrants in the Cottage area. Th e age of the 8-inch site loop is unknown.

3. Sanitary sewer - Th e sanitary sewer system connects to the sewer main that extends to a wastewater treatment plant located in El Portal. Underground grease traps are located in the Service Yard.

4. Propane - Th ere are three propane tanks located approximately halfway between the northwest corner of Th e Ahwahnee and the Employee Dormitory. Each tank has one-thousand gallon capacity, and the pad on which they are placed is sized to hold up to six tanks of this size. Th ese tanks feed the Kitchen area of Th e Ahwahnee and the Employee Dormitory.

5. Oil - Th ere is a large underground oil tank in Th e Ahwahnee Service Yard that feeds Th e Ahwahnee boilers. Th ere is also a smaller underground oil tank north of the Kitchen wing that feeds the emergency generator.

6. Steam - Pipes carrying steam and steam condensate run between Th e Ahwahnee Basement and Employee Dormitory. Th is piping was replaced within the last two years.

Plumbing

1. Th e Ahwahnee Th e domestic water system is fed from the 6-inch line located in the crawl space. Th e water fi rst passes through a dual pressure reducing station – originally set to 70 psi and 80 psi. Domestic hot water is generated in the Basement by two steam-fi red heat exchangers in 1500 gallon storage tanks. One of these tanks has been abandoned. Th ere is also a steam-fi red heat exchanger to pre-heat the incoming cold water. Multiple hot-water return pumps are utilized to maintain circulating hot water. Hot and cold water is distributed in the Basement and crawl space areas to multiple plumbing chases, which rise to the various fl oors. Th e plumbing chases are generally located between each pair of guest rooms. Th e domestic hot and cold water piping was replaced in approximately 1990. Th e heat exchangers and storage tanks are considerably older. Th e waste lines under the Kitchen were replaced in the early 1990s. Th e plumbing fi xtures and fi xture trim in the guest rooms have been replaced on a fairly regular schedule and are in very good condition. Th e plumbing fi xtures and fi xture trim in the service areas are in fair condition.

2. Th e Ahwahnee Cottages Domestic hot water is generated at individual electric water heaters. Th ese water heaters have been replaced on an as-needed basis. Th e plumbing fi xtures and fi xture trim have been replaced on a fairly regular schedule and are in very good condition.

3. Employee Dormitory Domestic hot water is generated by a steam-fi red heat exchanger in a storage tank in the women’s room. Th e plumbing fi xtures and fi xture trim are in fair condition.

Fire Sprinkler System Th e fi re sprinkler system is fed from the 6-inch domestic water line in the crawl space of Th e Ahwahnee. Following is a list of spaces that are fi re sprinklered:

1. Fift h and sixth fl oor corridors

2. Storage rooms

3. Gift Shop

At the time of this writing, the fi re sprinkler system is being upgraded. Th e entire building will be served by a new code-compliant fi re-suppression system.

Heating, Ventilating and Air Conditioning (HVAC) Systems

1. The Ahwahnee Central Plant - Th e Ahwahnee has a central plant for generating chilled water, steam and space-heating hot water. Th ere is a separate chiller building just west of the Kitchen that houses a chiller, cooling tower and associated pumps. Th e chiller is water cooled with a nominal capacity of 170 tons. Th e refrigerant is R-

22. Th ere is evidence of a leak at the cooling tower. Th ere is a fan coil that was added to the chiller building that serves the Staff Dining Room. Chilled water is distributed to the guest rooms, Dining Room, Gift Shop, Sweet Shop and women’s room. Th e chilled-water system was installed in approximately 1990. Steam is generated in Th e Ahwahnee Basement by two oil-fi red boilers.

Th ese boilers were installed in the mid-1980s. Th e steam feeds heat exchangers for generating space-heating hot water, domestic hot water and direct steam-fi red radiators in Th e Ahwahnee public spaces. Th e HVAC hot water is distributed to the guest rooms, Dining Room, Gift Shop, Sweet Shop and women’s rooms.

M echanical System s A ssessm ent

ARCHITECTURAL RESOURCES GROUPMechanical Systems Assessment

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Steam is also piped to the Employee Dormitory for space heating and domestic hot water generation. Th e space-heating hot-water system (heat exchangers, pumps and piping) was installed in approximately 1990. At that time, plans also were prepared to route hot and chilled water to the Cottages, but that portion of the system was not constructed. Th e control system is pneumatic.

Th e air compressor is located in the chiller building. Maintenance personnel that are familiar with the maintenance history of the chiller, tower, boilers, related pumps and controls were contacted but could not be reached.

Guest Rooms - Th e guest rooms are conditioned by four-pipe fan coils that are located in dropped ceiling areas or attic areas.

Th ese fan coils were installed in approximately 1990. Guest room bathrooms have an exhaust grille that opens into the plumbing chase. An exhaust fan located in the third fl oor attic space (east wing), and two exhaust fans located in the fi ft h fl oor attic space (south wing) draw air from the plumbing chases. Th ese fans are ducted to the tops of the plumbing chases, but the ductwork does not continue downward into the chases. Several bathroom exhaust grilles were investigated for air fl ow. Air fl ow was not detected at any of the grilles. One of the maintenance staff indicated that the bottoms of the plumbing chases were open to the crawl space below the ground fl oor. Th is could explain the lack of air fl ow at the exhaust grilles. In a few rooms, mold was noticed in or near the bathrooms.

Public Spaces - Of the public spaces, only the Dining Room, Gift Shop, Sweet Shop and women’s room are conditioned by hot-and chilled-water fan coils or air handlers. Th e Great Lounge, Solarium and Registration Lobby are heated by the original, steam-fi red radiators. Th e Ahwahnee Bar has a forced-air heating system located in the crawl space. Th ese spaces have large doors/ windows that are oft en left open in mild weather.

Kitchen - Th e Kitchen-area HVAC system has recently been upgraded. New Kitchen hoods, ductwork and exhaust fans have been installed. A new air-handling system has been installed, which includes an evaporative cooling module and a hot water coil for heating. Hot water for this coil is generated by a new LPG-fi red boiler. Th ere are small air-conditioning units in the Head Chef ’s Offi ce and the Kitchen Offi ce.

Basement - Th e two steam boilers, various heat exchangers, pumps, domestic hot-water storage tanks, pool fi lter, pool heater, and various electrical panels are located in the Basement. Th ere are many steam leaks and water leaks, which have resulted in rust, corrosion and insulation damage. In many locations, the insulation is missing, exposing such things as corroded piping.

During much of the year, and especially during spring and early summer, ground water enters the Basement. Various means are in use to drain or pump the water but they are not very successful.

Th e water on the fl oor presents a potential hazard.

Staff Locker Rooms - Th e HVAC system in the Locker Rooms consists of steam radiators and exhaust fans.

Elevator Equipment Room - Th e elevator equipment room has an abandoned exhaust fan, a portable fan (not ducted to the outside), and a portable cooling unit with the condenser air-ducted to the outside.

Other Service Areas – Th e generator room and the high voltage room each have exhaust fans.

2. The Ahwahnee Cottages Th e Cottages have electric wall heaters. Th ese heaters are cleaned on a regular basis and replaced as needed.

3. Employee Dormitory Th e Employee Dormitory has a forced-air heating system ducted to each of the rooms. Several through-the-wall air conditioners were noted on the north and south exterior walls.

Specific Equipment Items

1. Men’s room (ground fl oor) - Th e wall mounted exhaust fan does not have a dome cover.

2. Th ird fl oor attic space (east wing) - Th e exhaust fan serving the plumbing chases has very noisy belts. Also, at the fan discharge, a hole has been cut in the ductwork at the wall louver - presumably to ventilate the third fl oor attic space.

3. Fift h fl oor attic space (south wing) - Exhaust Fan EF 5-2 serving the plumbing chases has noisy belts and it emits signifi cant vibration. Th e pulley is not running true. In the same area, EF 5-1 is running smoothly.

4. Fift h fl oor attic space (south wing) – Th e storage room has a through-the-wall air conditioning unit, which discharges condenser air into the attic.

5. Fift h fl oor (hallway leading to the deck outside Room 507) – Th is hallway is warm and humid and should be ventilated. Th ere is a possible moisture issue.

6. Room 601 - Th e ceiling-mounted exhaust fan is noisy. Mold was noticed at the high-ceiling pocket.

7. Room 604 - Th e ceiling-mounted exhaust fan is noisy.

8. Room 607 - Th e ceiling-mounted exhaust fan has been removed and replaced with a ceiling grille, which is open to the attic.

9. Sixth fl oor - Th e through-the-wall air conditioning unit serving the (former) kitchen – now TV cable room – is draining condensate down the exterior wall.

Electrical, Lighting, and Fire Alarm Systems AssessmentARCHITECTURAL RESOURCES GROUP

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E L E C T R IC A L , L IG H T I NG , A N D F I R E

A L A R M SYST E M S AS SE S SM E N T

During the week of 1 June 2009, O’Mahony & Myer performed a site investigation at Th e Ahwahnee to review the existing conditions of the electrical, lighting, and signal systems. Th e purpose of the review was to evaluate the condition of the various systems and to comment on their ability to support the ongoing safe and functional use of the facility, while still maintaining the historical nature of the building and grounds. Below is a summary of the existing conditions and the recommended or required changes for each of the building systems noted.

Executive Summary Th e facility, electrical and lighting systems are generally functioning, with various additions made in the past at diff erent points in time.

Th is has left the overall electrical system infrastructure rather piece-meal, with many small sub-feeds and branches that support small loads here and there. Based on the main switchboard and distribution system panel space, the electrical infrastructure also appears to be close to maximum. Th e electrical system could benefi t from a more robust and organized distribution system in order to consolidate some of the smaller branches and to eliminate confusing conditions.

Th is will make future safety and maintenance more practical.

Lighting systems were retrofi tted in the past with fl uorescent sources wherever possible.

Th e building fi re alarm and protection systems are currently being designed for replacement, so their condition, although minimal now, will soon be up to current safety and fi re standards.

The Ahwahnee Main Building Power Service Th e facility is currently fed from the medium-voltage valley-feeder system to two diff erent service transformers. One transformer is a 500kVA dry-type unit located in an above-ground electric room at the southwest corner of the building. It serves the 1,200-Amp, 120/208V, 3-Phase, 4-Wire Main Electric Panel for the building, which is also located near the southwest corner of the building.

Th e second transformer is a below-grade outdoor transformer in a ventilated vault near the Chiller Building. It serves a 600-Amp, 277/480V, 3-Phase, 4-Wire Motor Control Center related to the mechanical loads.

Th e 1,200-Amp main service board located in the main electric room has no additional space for new sub-feed breakers. It is also not large enough to properly pass the full rated capacity of the 500kVA service transformer, which could support a 2,000-Amp 120/208V main panel, if required.

Th e main service panel currently sub-feeds various loads as shown on the overall electrical system 1-line diagram, which then also sub-feeds additional branch panels with yet another layer of sub-feeds below that. Th e overall distribution system confi guration is unclear and rather hard to follow, since many panels and branches have been installed at diff erent times and for diff erent purposes. Th e end result is a system that cannot be coordinated for proper overcurrent protection sequence, leaving the system open to possible nuisance tripping of larger feeder breakers when small loads have electrical short circuits. While this may not be a problem currently, time and future additions will add to the problem and continue the piece-meal nature of the system.

Th e 600-Amp Chiller Service was installed c. 1990 and is dedicated to the Chiller Plant and its associated loads. It is comprised of modern electrical equipment and is in good working order. No modifi cations are required, except as may be required to support future mechanical changes. See Recommendations below for placard requirements to address a code defi ciency related to the presence of multiple services in the Chiller Building.

Th e main building electric service also includes a power factor correction capacitor bank, which was installed c. 1990 during the mechanical systems upgrade. It is not exactly clear why the service includes this device. Typically, it is intended to help correct the electrical eff ects of large inductive loads, but the correction capacitor bank, as installed here, could cause resonance problems with electronic loads such as elevator controllers or variable frequency drives.

Emergency Power System Th e building has a 420kW, 120/208V emergency generator located at the Main Electric Room. Th e unit has a 1,450-Amp capacity and is fed into the main electric service via a 1,200-Amp rated automatic transfer switch. Upon loss of the normal valley power system, the transfer switch engages the generator, which then serves all loads in the building with the exception of the newer 480V Chiller Building electric service. Th e 120/208V panel at the Chiller Building is on emergency power, so it provides various mechanical loads with back-up power when needed.

A second 150-Amp automatic transfer switch was recently installed upstairs above the main electric room, which is fed from a tap off of the larger emergency system downstairs. Th e second transfer switch engages power to a 480V Motor Control Center via a 75kVA transformer located upstairs in order to serve additional mechanical loads in the building.

Th is branch then also includes another step-down transformer back to 120/208V for a branch panel on the emergency system.

Th ese conditions should be consolidated as outlined in the recommendations section below.

Electrical, Lighting and Fire A larm

System s A

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Branch Power Systems Since the construction of the building includes many concrete walls and fl oors, passage of raceways through the walls and concealed routing is diffi cult. Various systems have been already routed through various areas with some success. Additional routings will need to be coordinated carefully with the architectural design for each area in order to limit the visual and historical impact to the building. Th is will be most important for the fi re alarm system installation, which will require various ceiling and wall mounted devices in all areas.

A number of the existing power panels do not have the required code clearance for width and depth of the working space.

Various power panels in the facility are also of a fairly old vintage and are at the end of their useful life.

Th e wiring systems within the walls are not visible or easily accessible in order to verify their adequacy, but they can be assumed to be rather old. Since replacement of the wiring systems is not practical, replacement of the power panels that feed them will be important to provide proper protection of the conductors and safety to the guests and staff .

Lighting System Th e interior and exterior lighting systems have been maintained with historic-style light fi xtures, but most of the sources have been upgraded from the original incandescent lamps to more energy-effi cient and longer-life compact fl uorescent sources. Th is includes the small-scale candelabra lamps within the historic fi xtures located throughout the public areas, which are also small-scale fl uorescent sources.

Very few incandescent sources were noted; they…