American_Legation_Final_Report_30_September_2014.pdf

Condition Assessment and

Seismic Evaluation

American Legation

Tangier, Morocco

Final Report

September 30, 2014

Prepared for:

US Department of State

OBO/PDCS/DE/CSE

1701 North Fort Meyer Drive

Arlington, VA 22209

Prepared by:

Wiss, Janney, Elstner Associates, Inc.

2000 Powell Street, Suite 1650

Emeryville, CA 94608

510-428-2907

Condition Assessment and Seismic Evaluation

Brian E. Kehoe

Stephen J. Kelley

Final Report

September 30, 2014 WJE No. 2013.4056

Prepared for:

U.S. Department of State

OBO/PDCS/DE/CSE

1701 North Fort Meyer Drive Arlington, CA 22209

Prepared by:

Wiss, Janney, Elstner Associates, Inc.

2000 Powell Street, Suite 1650 Emeryville, California 94608

510.428.2907 tel | 510.428.0456 fax

TABLE OF CONTENTS

Background Building Description Building Condition and Seismic Assessment

General Condition Assessment Neighboring Buildings Seismic Assessment Original Building Kitchen/Dining Room Addition Classroom Addition Pavilion Arabe Research Library

Pavilion Arabe Investigation Wall Cracking Investigation Geotechnical Investigation

Test Pit 1 Test Pit 2 Test Pit 3

Roof and Terrace Investigation Inspection of damaged roofing at second floor of Pavilion Arabe Water drainage testing in the courtyard to the north of Pavilion Arabe

Conclusions and Recommendations Pavilion Arabe Settlement Pavilion Arabe Water Leakage Water Drainage in the Courtyard Seismic Hazard Rating Repair and Maintenance

Appendix A - Building Inspection Worksheets

Appendix B - Summary Status Sheets

Appendix C - Pavilion Arabe Crack Maps

Appendix D - Pavilion Arabe Crack Gauge Readings

Appendix E - Geotechnical Report (Original and Translated)

Appendix F - Pavilion Arabe Ceiling Probe Locations

Appendix G - Preliminary Repair Concepts

Appendix H - ROM Cost Estimate

Condition Assessment and Seismic Evaluation Wiss, Janney, Elstner Associates, Inc.

American Legation, Tangier, Morocco 1 Final Report September 30, 2014

Condition Assessment and Seismic Evaluation

BACKGROUND

In response to the statement of work prepared by OBO, Wiss, Janney, Elstner Associates, Inc. (WJE) has performed a structural and seismic assessment of the buildings that comprise the American Legation in

Tangier, Morocco. This report provides a general assessment of the buildings, a preliminary seismic evaluation of the buildings, and an evaluation of the cracking and settlement of the Pavilion Arabe structure.

A separate geotechnical evaluation of the soil at Pavilion Arabe has been performed by GEORET of

Tangier, Morocco.

In 2011, WJE prepared a Historic Structures Report (HSR) on the Tangier American Legation for OBO.

The purpose of the report was to identify original and lost design, describe the current conditions including deterioration and causes, define significant features and establish a period of significance and propose treatments to maintain its historic character. Investigation of historical documents and evaluation of existing materials was used to identify aspects of the configuration and materials of the original building and those features that were not previously documented. The HSR includes documentation of the physical evolution of the building since its acquisition. As part of the preparation of the HSR a three-dimensional laser scan of the building was performed and serves as the basis for available drawings of the property.

BUILDING DESCRIPTION

The Tangier American Legation property was presented to the United States by Sultan Moulay Suliman in

1821 and is the longest-held property acquired by the United States for a diplomatic mission. The Legation is also the only property outside of the United States that has been designated a National Historic Landmark.

The building is located in the Medina in Tangier. The Medina is the old walled city, which is characterized by closely-spaced buildings accessed via narrow alleys primarily by pedestrians.

The Tangier American Legation consists of a number of buildings that have been expanded and modified over time. Figure 1 shows an isometric view of the buildings based on laser scan data conducted as part of the preparation of the HSR. The structure of the building that was originally presented to the United States is not readily apparent and it is unknown whether any of that structure still exists. The Tangier American

Legation was completely rebuilt in 1848 as a two-story structure that spans across Rue d’Amerique to connect two previously existing buildings. Rue d’Amerique is a pedestrian thoroughfare that leads from the entrance to the Medina on the southeast side. The second floor included a large reception room and there was a series of roof-top terraces over the footprint of the building. A plan of the first and second floors of the building that existed in 1849 is shown in Figure 2. Hereafter the structure that existed circa 1921 will be referred to as the Original Building.

Following a renovation of the Original Building in 1921, a series of additions to the Original Building were constructed between 1926 and 1930. These included a third and fourth floor above the Original Building, a two-story kitchen/dining room addition on the west side of Rue d’Amerique, and a one-story building with a roof-top terrace on the east side of Rue d’Amerique.

The Pavilion Arabe structure was constructed in 1931 as a two-story structure on the east side of Rue d’Amerique. This structure abuts adjacent buildings on two sides: a five-story building to the south of

Pavilion Arabe, and a two-story building to the east. A roof-top terrace was constructed above the second floor and a portion of the terrace has been covered. A single-story portion of this addition adjoins an addition

American Legation, Tangier, Morocco 2 Final Report September 30, 2014 to the Original Building on the east side of Rue d’Amerique. The covered portion of the terrace at the third floor was enclosed later.

An adjacent house was purchased circa 1941 to be included as part of the American Legation. This building is a two-story structure adjacent to the kitchen/dining room addition of the Original Building and across

Rue d’Amerique from Pavilion Arabe. This house is currently referred as the Research Library. Two roof-top storage structures have subsequently been added to the roof.

A fifth floor was added to the Original Building in 1999 and is referred to as the Minzah Room.

Figure 1. 3-dimensional representation of the Tangier American Legation looking northwest.

Floor plans of the current configuration of the building are provided in Figures 3 through 6 for the first through fourth floors. In each figure, the various portions of the building that were separately constructed are denoted with colored shading. Although the kitchen/dining room addition and the classroom addition were constructed at the same time, they are considered separate structures since they are not connected to each other. Note that it is difficult to exactly define a structure since some walls appear to be common to adjacent structures within the Tangier American Legation complex and with walls of the neighboring buildings. For reference purposes, the threshold of the main entrance on the west side of Rue d’Amerique was set as the reference datum used on the attached drawings, as indicated in Figure 3.

Minzah Room (1999)

Pavilion

Arabe

(1931)

Research

Library

(1941)

American Legation, Tangier, Morocco 3 Final Report September 30, 2014

Figure 2. First and second floor plans of the building as it existed in 1849

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The majority of the Original Building and Pavilion Arabe are currently used as a museum by the Tangier

American Legation Institute for Moroccan Studies (TALIM). There are living quarters for the director of the TALIM, Mr. Gerald Loftus, that are in both the Original Building and the kitchen/dining room addition and guest accommodations in the Original Building. The third floor of Pavilion Arabe is used as a guest apartment for student interns. The adjacent house that was purchased in 1941 is currently used as a research library. The single-story addition on the east side of Rue d’Amerique is used as a classroom and office for the TALIM.

Figure 3. First floor plan shown approximate areas of the separately constructed structures

Original Building

Kitchen/Dining Room Addition

Classroom Addition

Pavilion Arabe Research

Library

Stair Tower and one-story structure

Reference Datum

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Figure 4. Second floor plan showing areas of separately constructed structures

Kitchen/Dining Room Addition

Classroom Addition

Pavilion Arabe Research

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Figure 5. Third floor plan showing areas of separately constructed structures

Kitchen/Dining Room Addition

Pavilion Arabe

Research

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Figure 6. Fourth floor plan showing areas of separately constructed structures

The walls of the building complex are constructed of unreinforced masonry covered with cement plaster

(stucco). The masonry consists of a combination of hollow clay tiles and uncoursed stones typically bound with cement mortar. The wall thicknesses vary from about 18 cm to about 50 cm. The walls are assumed to be founded on strip footings. The floor construction varies throughout the structures and includes some areas with wood framing supporting a cast-in-place concrete topping and some areas with shallow brick arches spanning between steel I-beams. The roofs include both steep sloped framing with clay tiles and shallow sloped framing covered with a roofing membrane. Portions of the flat roof have a concrete topping and are used as terraces.

BUILDING CONDITION AND SEISMIC ASSESSMENT

General Condition Assessment

The building exterior includes a variety of stucco detailing of columns, arches, parapets, copings, and embossed seals to help define the architectural character of the building. Examples of the detailing are shown in Figure 7 and 8. The general shapes of the walls are created with brick or stone masonry that has been subsequently coated with stucco. Localized areas of the exterior walls may be constructed with reinforced concrete.

Kitchen/Dining Room Addition

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Figure 7. Stucco detailing at Pavilion Arabe

Figure 8. Stucco detailing at covered second floor area of the classroom addition

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In general, each of the structures that comprise the Tangier American Legation has experienced widespread hairline cracking of the stucco and interior plaster. An example of typical plaster cracking is shown in

Figure 9.

The interior walls surfaces within the museum portions of the building are generally well maintained, with few visible cracks and relatively recent paint.

Figure 9. Cracking in masonry wall of the Perdicaris Room at the second floor of the Original Building

There is extensive evidence of water intrusion on the wall surfaces at several locations in the structures, with the most significant damage in the Pavilion Arabe that has experienced extensive peeling and blistering paint and visible staining, as shown in Figure 10. Leakage staining was also noted at the ceiling below the roof in the Original Building, as shown in Figure 11.

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Figure 10. Water staining and peeling paint on north wall of Pavilion Arabe

Figure 11. Water leakage at ceiling in the central stairwell of the Original

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Where the ceiling is constructed with plaster on a flat surface, there has been cracking of the ceiling plaster, as shown in Figure 12.

Figure 12. Cracked plaster ceiling in the kitchen/dining room addition

The floor framing constructed with shallow brick arches are typically exposed to view on the underside.

The brick and the steel I-beams have been coated with plaster and painted. There are some areas where the steel beam has corroded, causing corrosion stains to be visible. In the Original Building, there is an area of the ceiling where some of the plaster coating on the bottom of the steel beam has spalled, as shown in Figure

13.

American Legation, Tangier, Morocco 12 Final Report September 30, 2014

Figure 13. Spalled plaster at steel beam in the ceiling of the Original Building

Some of the exposed wood framing has deteriorated due to decay and possibly from insect infestation according to the maintenance staff. Examples of wood decay of the roof framing in the Pavilion Arabe at the roof above the third floor and the third floor terrace framing are shown in Figure 14 and Figure 15, respectively.

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Figure 14. Decayed ends of wood roof joists supporting the third floor roof at

Pavilion Arabe

Figure 15. Decayed wood floor framing below the third floor terrace at the

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Neighboring Buildings

To the south of the Tangier American Legation, there are neighboring buildings on each side of Rue d’Amerique. The neighboring buildings are of interest because they abut the Tangier American Legation, and possibly may share party walls with the Legation. These neighboring buildings were apparently initially constructed separately but have now come in contact with each other at the third floor level, as shown in

Figure 16 and 17.

Figure 16. View looking southward at adjacent buildings in contact with each other at the third floor level above Rue d’Amerique. The five-story building to the south of Pavilion Arabe is on the right and the house adjacent to the Research

Library is on the left. Note the slender diagonal metal struts supporting the cantilever portion of the west building (arrows).

On September 24, 2013, WJE visited the neighboring building on the west side of Rue d’Amerique, which abuts the research library portion of the Legation. The second floor of this building includes a portion that

American Legation, Tangier, Morocco 15 Final Report September 30, 2014 cantilevers past the exterior wall at the first floor and extends over Rue d’Amerique. The cantilever is partially supported with a series of slender metal diagonal struts, as shown in Figure 16.

At the second floor of the west neighboring building, the floor slopes downward toward Rue d’Amerique.

The slope was measured to be about 2 percent. The exterior wall of the second floor that is closest to the building across Rue d’Amerique is out of plumb by about 1 percent. There is a wood window/door on the north wall of the room that cantilevers over Rue d’Amerique. There are gaps between the window/door and the head and sill and between indicative of downward displacement toward Rue d’Amerique, as shown in

Figure 17.

Figure 17. Uneven gaps between doors/windows and at the base of door/window on the north wall at second floor of the building adjacent to the Research

Library.

The third floor level of the west building includes a covered terrace that extends over the cantilever portion of the second floor level. There is a parapet around the perimeter of the terrace. A portion of this parapet is in contact with the corner of the building across Rue d’Amerique, as shown in Figure 18. There is a metal-framed awning covering the terrace. One of the framing members for this awning has come in contact with the building across Rue d’Amerique, as shown in Figure 19.

At the corner of the third floor terrace where the buildings have come in contact, the top of the parapet wall on the north side of the terrace of the west building is sloped downward, as shown in Figure 20. The floor is relatively flat in the direction parallel to the parapet wall on the north side. At the corner of the terrace to the south of the area of contact, the floor slopes in downward in two directions toward a floor drain located above the area of the building that is not cantilevered.

American Legation, Tangier, Morocco 16 Final Report September 30, 2014

Figure 18. Parapet wall of terrace in contact with the building across Rue d’Amerique. The building west of Rue d’Amerique and adjacent to the Research

Library is to the left and the five-story building adjacent to Pavilion Arabe is to the right.

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Figure 19. Canopy framing above third floor in contact with adjacent building

Figure 20. North parapet at third floor of west building sloped downward to the right

American Legation, Tangier, Morocco 18 Final Report September 30, 2014

From the terrace of the west building, the exterior wall of the building on the east side of Rue d’Amerique was measured and found to be plumb, within the accuracy of the level. This east building abuts the Pavilion

Arabe.

WJE visited the building on the east side of Rue d’Amerique, adjacent to Pavilion Arabe on September 25, 2013. This building is five stories tall and includes a first floor apartment that has a separate entrance from the upper floor apartments. Within the first floor apartment, we observed that the wall of the building that abuts Pavilion Arabe is constructed with reinforced concrete columns and beams with masonry infill walls, as shown in Figure 21. The thickness of the infill walls could not be determined. There were no apparent cracking of the masonry infill walls that abut Pavilion Arabe.

Along the first floor hallway parallel to the wall abutting Pavilion Arabe, the tile wainscot was partially delaminated with an accompanying crack across the floor. This occurs approximately in line with an interior column. No other significant cracking conditions were pointed out by the residents of the first floor unit.

Figure 21. Concrete beams and columns with masonry infill walls in the east building adjacent to Pavilion Arabe

American Legation, Tangier, Morocco 19 Final Report September 30, 2014

Figure 22. Cracking floor tile joint in hallway of the east building adjacent to

WJE also visited one of the upper story residential units in the east building as well as the roof. There was no apparent distress in the residential unit visited and no distress was reported. However, full access to the wall abutting Pavilion Arabe was not provided by the occupant.

At the roof level of the building, there were no indications of distress or settlement of the wall abutting

Pavilion Arabe. See Figure 23. This wall is constructed with a combination of hollow clay tile and stone masonry. The concrete floor slab of the fifth floor of the building is visible on the outside face of the wall.

The roof level did not have any noticeable slope indicative of settlement of the building.

American Legation, Tangier, Morocco 20 Final Report September 30, 2014

Figure 23. Concrete beam and floor slab construction visible at exterior wall of building adjacent to Pavilion Arabe (arrows)

A vertical crack was observed between this building and the adjacent building to the northeast, which also abuts Pavilion Arabe, as shown in Figure 24.

American Legation, Tangier, Morocco 21 Final Report September 30, 2014

Figure 24. Vertical separation at intersection of buildings adjacent to Pavilion

Arabe

Seismic Assessment

WJE performed a Seismic Inventory Plus evaluation of the structures comprising the Tangier American

Legation. The Seismic Inventory Plus evaluation included a walk-through of significant portions of the structures and review of the available floor plans and sections from the HSR. For the purpose of the Seismic

Inventory Plus evaluation, each of the five structures described in the Building Description section of the report above, was evaluated separately. A Building Inspection Worksheet was filled out for each of the structures and is attached as Appendix A. Summary Status Sheets for each structure are attached in

Appendix B.

Although the structures were considered separately for the purpose of the Seismic Inventory Plus evaluation, the buildings will likely perform mostly as a single building when responding to an earthquake due to a lack of seismic joints between buildings. Additionally, because the structures of the Tangier

American Legation abut or have common walls with neighboring buildings on multiple sides, the actual behavior of the structures involves a complex interaction of all of the neighboring buildings, and by extension, a large portion of the buildings on the south side of the Medina, which are all somewhat interconnected or abutting with no space for the structures to displace independently. Due to the adjacency of the buildings, pounding of the buildings is likely to occur during earthquake shaking that may adversely

American Legation, Tangier, Morocco 22 Final Report September 30, 2014 affect the behavior of the structures. All of the walls in the structures have been assumed to be constructed of unreinforced masonry, which may be hollow clay tile, uncoursed stones, or some combination thereof.

In accordance with the task order, the seismicity for the Tangier site was assumed to be equivalent to UBC

1997 Zone 3 with spectral response parameters of Ss = 1.13 g and S1 = 0.45g for the uniform hazard spectra of the Maximum Considered Earthquake. This level of seismicity is roughly equivalent to the seismicity of

Olympia, Washington (Ss = 1.15, S1 = 0.43).

Original Building

The Original Building of the Tangier American Legation was constructed as a two-story structure. There have been several vertical additions, with the most recent being the addition of the Minzah Room at the fifth floor level. Although the walls of the vertical additions have mostly aligned with the walls of the

Original Building, it is not known whether any strengthening of the walls or foundations of the Original

Building was done to accommodate the weight or seismic forces from the added stories.

This structure includes an open atrium in the middle that creates a diaphragm discontinuity. There is also a vertical irregularity due to the set-back created by the upper stories having a smaller footprint than the stories below. Because of the irregularities and the apparent lack of strengthening to account for the added stories, this structure is assigned a Seismic Hazard Rating of Very Poor.

Kitchen/Dining Room Addition

The addition of the kitchen and dining room at the first and second stories respectively does not appear to have been constructed as a separate, isolated structure. As a result, it appears that some of the gravity loads are supported by the Original Building and some may be supported by the walls of the Research Library structure. It is unclear whether the connections to these buildings, if they exist, are capable or resisting any lateral loads. As an isolated structure, this addition does not appear to have a sufficient amount of unreinforced masonry wall in each direction to resist the expected seismic forces. A third story was added to this structure and it is unclear whether any strengthening of the walls or foundation was performed as a result of the added loads.

This structure also has a plan irregularity due to the re-entrant corner at the intersection of the stair tower to the remainder of the structure. There is a vertical irregularity due to an interior wall on the third floor being discontinuous at the second story. As a result of the inadequate independent structural walls and the irregularities, this structure is assigned a Seismic Hazard Rating of Very Poor.

Classroom Addition

The classroom addition is essentially a single-story structure constructed with brick columns supporting an elevated terrace. The structure is L-shaped in plan. Two sides of the building have masonry walls that abut or are part of adjacent buildings. The sides that face the adjoining courtyard are mostly open. A portion of the terraced roof at the second floor is covered with a concrete roof slab with masonry walls around three sides of the roof.

The structure has a plan irregularity due to the re-entrant corner and a torsional irregularity due to the presence of openings on the sides facing the courtyard. Since the building is short and appears to have a substantial amount of wall in each direction, the lateral force resistance appears adequate relative to similar structures. The portion of the covered terrace at the second floor has a relatively heavy roof and an irregularity due to being open on one side. However, there appears to be sufficient walls along three sides of the roof and adjoining walls along the open side that there is adequate resistance for the covered portion of the terrace at the second floor.

American Legation, Tangier, Morocco 23 Final Report September 30, 2014

The columns are relatively brittle brick masonry and the strength of the masonry walls is unknown. As a result of the irregularities and the brittleness of the structural framing, this structure is assigned a Seismic

Hazard Rating of Poor.

The Pavilion Arabe structure is predominantly a two story structure with a penthouse on the third floor and a small, one-story wing of building to the north. The walls are constructed with unreinforced masonry. The floors are constructed with a combination of shallow brick arches spanning between steel beams and wood joists supporting a wood deck and concrete topping slab. The roof of the penthouse at the third floor is wood framed with clay tiles. The building is roughly rectangular in plan, with the one-story wing creating a re-entrant corner. The walls are supported on strip footings that appear to be unreinforced masonry walls from a previous building, as described below.

The building has a plan irregularity due to the side facing the courtyard (north side) being mostly open with no solid walls. The remaining perimeter walls are solid. Several of the walls are distressed with significant cracking due possibly to settlement. Some of the floor framing supporting the third floor terrace is decayed due to water infiltration. The third floor roof framing appears to be supported on the wall of the adjacent building to the south. There are a number of nonstructural falling hazards, including the clay roof tiles and the unreinforced masonry parapets at the third floor. These parapets are crenulated and not a continuous parapet and are therefore likely to behave as a series of unreinforced masonry appendages rather than as a single element.

There appears to be a significant amount of masonry walls relative to the building size to resist seismic forces. The poor condition of the building due to settlement and water leakage is likely to increase the amount of seismic damage that the building will experience. There are also a number of potential falling hazards, including the third floor roof that may be damaged due to differential movement between Pavilion

Arabe and the adjacent building. This structure is assigned a Seismic Hazard Rating of Poor Minus.

Research Library

The building currently used as a research library is a two-story structure with two penthouse structures on the roof. The building has an interior atrium that is open at the second floor and roof with a skylight at the roof level. There are four sections of building surrounding the atrium; three of these sections are roughly rectangular rooms that have solid walls along the sides that do not face the atrium. The fourth section of the building includes a stairwell. The floor levels in the stairwell section are offset vertically from the remainder of the structure, creating a diaphragm discontinuity.

One of the two penthouse structures is constructed with unreinforced masonry walls in a rectangular configuration and these walls support a concrete roof slab. The other penthouse structure is reportedly newer and has unreinforced masonry walls and a wood ceiling and a roof with clay tiles attached to wood framing with no sheathing.

The structure has a plan irregularity due to the atrium openings at each level and a vertical irregularity due to the offset elevation of the floors in one section. However, the remaining sections of the building have a relatively substantial amount of masonry wall relative to the area of the rooms. The section with offset floor levels also has relative substantial walls. The adjoining kitchen/dining room addition may transfer additional loads to the structure compared to what would be anticipated if this structure were completely isolated.

American Legation, Tangier, Morocco 24 Final Report September 30, 2014

The building’s clay tile roof on the penthouse creates a potential falling hazard. This structure is assigned a Seismic Hazard Rating of Poor.

PAVILION ARABE INVESTIGATION

The Pavilion Arabe structure has been experiencing distress due to water leakage and cracking of the masonry walls. An overview of the structure is provided in Figure 25. Because of the distress, structural, geotechnical, and water drainage investigations have been conducted as described below.

Figure 25. Exterior view of Pavilion Arabe

Wall Cracking Investigation

The interior and exterior walls of the structure have experienced a considerable amount of cracking. For reference purposes, the side of the structure that faces the courtyard will be referred to as the north side. In general, the large cracks are diagonal and indicative of possible settlement of the southeast corner of the building.

The walls of the structure are unreinforced masonry that are covered with plaster. On the south exterior wall and the east and west walls of Room 162 at the first floor, an interior clay tile wall about 10 cm thick has been constructed in front of each of these particular structural masonry walls. These clay tile walls are an addition to the original construction and the space between the original and added walls is vented. The

American Legation, Tangier, Morocco 25 Final Report September 30, 2014 surfaces of the added walls, as well as the surfaces of the originally constructed walls without additional walls, are experiencing cracking of the masonry and plaster along with blistering and peeling paint. WJE observed each of the accessible faces of the walls of the structure and recorded the observed damage on wall elevations. Copies of the crack maps are included in Appendix C. At selected locations along cracks, WJE measured the width of the cracks at the surface. The crack widths are recorded on the crack maps.

Examples of the cracking of the walls are shown in Figure 26 and 27.

Figure 26. Cracking in first floor exterior wall at Pavilion Arabe

American Legation, Tangier, Morocco 26 Final Report September 30, 2014

Figure 27. Diagonal crack in east exterior wall at the first floor of Pavilion

Arabe

On September 23, 2013, WJE installed crack movement gauges across cracks at five locations within the structure to allow for recording the movement of the cracks over time. The locations of the crack gauges are shown in Figure 28. The gauges have been labeled with the room number and the side of the room that the wall with the crack gauge is installed. WJE recorded the initial crack width adjacent to each crack location at the time the crack gauges were installed. Photos of each of the crack gauges are shown in Figures

29 through 33. The crack gauges were placed on original masonry walls and not clay tile wall additions.

The crack gauges consist of two pieces of plastic; each of which is adhered to the wall on either side of the crack and lapped over each other. On one piece, there is a fine grid of black lines. The other piece is clear plastic with two perpendicular red lines. When initially installed, the red lines align with the central lines of the grid on the opposite piece. If relative movement of the wall across the crack occurs, the movement will be indicated by relative movement of the red lines compared to the grid of black lines.

American Legation, Tangier, Morocco 27 Final Report September 30, 2014

Figure 28. Floor plans of Pavilion Arabe showing locations of crack gauges

163N

163S

263N

263S

363N

American Legation, Tangier, Morocco 28 Final Report September 30, 2014

Figure 29. Crack gauge 163N at first floor north exterior wall

Figure 30. Crack gauge 163S at first floor north interior wall

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Figure 31. Crack gauge 263N at second floor north exterior wall

Figure 32. Crack gauge 262E at second floor east exterior wall

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Figure 33. Crack gauge 363N at third floor north exterior wall

On September 27, 2013, WJE recorded the configuration of the red lines of each of the crack gauges onto forms provided by the crack gauge manufacturer. There was no noticeable movement indicated at any of the cracks.

Prior to leaving the site, WJE instructed Mr. Loftus and members of the facility maintenance staff on the procedures for recording the crack gauges. They were instructed to document the crack gauges conditions every other month onto copies of the forms that were left with the staff at the Tangier American Legation.

Follow-up observations of the crack gauges were performed November 29, 2013, January 29, 2014, and

April 4, 2014. A copy of the forms with the crack gauge recordings for each crack gauge on each date is provided in Appendix D. The crack gauges indicate that there had been no significant change in the crack gauges except at the north crack gauge on the first floor of room 163 (163N) that shows widening of the crack by about 1 mm from November 2013 to January 2014.

Geotechnical Investigation

A geotechnical investigation of the site was performed by GEORET, a geotechnical engineer engaged by the staff at the U.S. Embassy in Rabat. The investigation consisted of excavating three test pits within the

Pavilion Arabe. The locations for the test pit were chosen by WJE. Each test pit was approximately 1 meter square. The locations of the test pits are shown in Figure 34. WJE’s observations of the test pits are described below.

American Legation, Tangier, Morocco 31 Final Report September 30, 2014

Figure 34. First floor plan showing locations of test pits

At each of the test pits, the contractor carefully removed the finished tile floor, sawcut and chipped out the concrete slab-on-ground, and hand excavated the soil. As the floor was covered with original multi-colored cast concrete tiles, every effort was made to remove them without damage. WJE observed each of the test pit excavations and recorded notes regarding the conditions of the soil and the adjacent foundation. A summary of our observations are provided below. Soil samples from below the bottom of the excavation were removed for testing by the geotechnical engineer. The geotechnical engineer, Mr. Ahmed Kaissi of

GEORET, provided a separate report regarding the condition of soil. Copies of the original GEORET report

(in French) along with the translated version are included as Appendix F.

While he was at the site, WJE briefly interviewed Mr. Kaissi, who reported that the buildings in the Medina area typically have foundations that extend down to rock. He also stated that the fill material used in the

Medina area predominantly comes from a common location.

American Legation, Tangier, Morocco 32 Final Report September 30, 2014

Test Pit 1

The area chosen for the test pit is shown in Figure 35. At this location, the finish floor was noted to be sloped downward toward the east wall for the two rows of floor tiles closest to the wall. There are several wide cracks in the wall adjacent to the excavation and a crack gauge had been installed at one of these cracks. The soil beneath the finished slab consists of brownish clay with sand, large stones, and occasional fragments of clay masonry, as shown in Figure 36.

Figure 35. Location of Test Pit 1. Sloped area toward the east wall from the dashed line.

American Legation, Tangier, Morocco 33 Final Report September 30, 2014

Figure 36. Large stones mixed with soil beneath floor slab

At a depth of about 56 cm below the finished floor level, there was a relatively flat surface encountered that appeared to be a floor slab of a previous construction. This floor slab appeared to have been formed from soil mixed with lime. The thickness of the floor was about 10 cm. The top surface of this floor had a red coating. About 23 cm below the top of the red-coated floor, there was another floor of similar, probably earlier, construction with a white top surface coating. These floors are indicated in Figure 37.

The soil encountered between the red-coated floor and the white-coated floor was slightly different than the soil encountered in the upper portion of the excavation; it was darker in color and appeared to have more clay content. This soil was also mixed with large stones and brick fragments.

The soil below the white-coated floor appeared to have much more clay content and was also mixed with stones and brick fragments. The soil at the base of the foundation is reported by GEORET to be brownish clay. GEORET reported no water seeping into this test pit. Table 1 below summarizes the various layers encountered at Test Pit 1.

Table 1 - Test Pit 1 Observations Depth Below Top of Floor Tile Condition Observed

0 - 10 cm Concrete slab

10 - 53 cm Mixture of sandy silt and large gravel and masonry fragments

53 - 63 cm “Red” plaster floor slab

63 - 79 cm Clay mixed with gravel and masonry fragments

79 - 89 cm “White” plaster floor slab

89 - 94 cm (Bottom of excavation) Clay

American Legation, Tangier, Morocco 34 Final Report September 30, 2014

Figure 37. Floor slabs from previous constructions at Test Pit 1 indicated with red arrow and white arrow

Along the side of the excavation, the foundation for the east wall of Pavilion Arabe was exposed. The upper portion of the foundation consists of large stones and brick fragments with cement mortar. Below the top of the red floor, the side of the foundation has a thin plaster coating, as shown in Figure 38. The bottom of the footing appeared to be at a depth of about 94 cm from the top of the finish surface. At about 33 cm below the top of the finish surface, the footing stepped inward toward the room, presumably indicating that the footing was wider. Below the level of the red-coated floor, the plaster-coated portion of the footing stepped further inward.

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Figure 38. Plaster coating on face of footing below level of red-coated floor (red arrow) with plaster coating on side of foundation wall (white arrow)

Test Pit 2

The area excavated for Test Pit 2 is shown in Figure 34. This location is at the intersection of the south exterior wall of Pavilion Arabe that abuts the adjacent five-story building and a perpendicular interior wall.

The interior wall adjacent to this excavation has a wide diagonal crack at which a crack gauge was installed.

The condition of the floor slab prior to excavation is shown in Figure 39.

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Figure 39. Location of Test Pit 2 (Exterior wall indicated by arrow)

After removal of the finish floor and concrete slab, the soil encountered was similar to that encountered in

Test Pit 1. Along the exterior wall, at a depth of about 60 cm below the finish floor, a floor surface from a previous construction was encountered, similar to that of the red floor in Test Pit 1. On the opposite side of the excavation, the previous floor was encountered at a depth of about 69 cm below the top of the finish floor, as shown in Figure 40. The upper section of soil had noticeable voids that extended under the unexcavated portions of slab, as shown in Figure 41, and these voids did not appear to have occurred as a result of the excavation. GEORET reported no water seeping into this test pit. Table 2 below summarizes the observations within Test Pit 2.

Table 2 - Test Pit 2 Observations

0 - 10 cm Concrete slab

10 - 59 cm Mixture of sandy silt and large gravel and masonry fragments

59 - 69 cm “Red” plaster floor slab

69 - 90 cm (Bottom of excavation) Clay mixed with gravel and masonry fragments

American Legation, Tangier, Morocco 37 Final Report September 30, 2014

Figure 40. Old floor slab indicated by arrow

Figure 41. Void in soil adjacent to excavation

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Along the exterior wall, the footing was coated with plaster down to the level of the old floor. The plaster coating appeared to extend down the footing and transition horizontally to be a coating on the old floor.

Adjacent to the wall, there is a brick pilaster that is finished decoratively with plaster. The bottom of the pilaster is at the level of the top of the old floor and the pilaster is cut off slightly below the current floor, as shown in Figure 42. There is a thickened brick footing below the level of the old floor.

The south exterior wall of the Pavilion Arabe has a nonstructural wall on the inside of the structural wall with a void between the two walls. The nonstructural wall is constructed with hollow clay tiles with a coat of cement plaster on the inside face. The clay tile wall is about 10 cm thick and there is a gap of about 4 cm between the structural wall and the nonstructural wall. A thin layer of building paper is adjacent to the structural wall, as shown in Figure 43. This nonstructural wall is supported on the current finish floor whereas the structural wall aligns with the footing.

Figure 42. Plaster coating on footing down to level of old floor (red arrow) and plaster on brick pilaster

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Figure 43. Hollow clay tile nonstructural walls and building paper adjacent to structural wall as seen through the vent in the clay tile wall.

The perpendicular interior wall is supported on a foundation constructed of a combination of large stones and brick in cement mortar. At the intersection of the interior foundation and the exterior foundation, shown in Figure 44, it appeared that the upper portion of the interior foundation was socketed into the exterior foundation. The footing for the interior wall widens below the level of the old floor. The excavation extended down about 95 cm, but depth of the footings could not be determined.

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Figure 44. Intersection of footings for interior wall (right) and exterior wall (left)

Test Pit 3

The location of Test Pit 3 is at the south exterior wall of Pavilion Arabe and is shown in Figure 45. There was a visible separation between the top of the finish floor and the adjacent tile baseboard indicative of floor slab settlement at this location. The condition of the floor prior to the excavation is also shown in

Figure 45.

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Figure 45. Location of Test Pit 3. Location of separation of wall from floor slab indicated by arrow.

The soil conditions encountered below the finish floor were similar to those at the other test pits. The upper portion of the soil consisted of a mixture of silty sand and stones to a depth of about 60 cm where a floor slab from a previous construction was found. This old floor slab was also coated red and was about 10 cm thick. About 23 cm below the top of the red-coated floor, a second old floor was encountered, which is coated white. The remnants of a clay tile wall with plaster on both sides intersects the exterior footing, as shown in Figure 46. This wall is about 10 cm thick and the bottom of this wall is at the top of the lower, white-coated floor. GEORET reported no water seeping into this test pit. Table 3 below summarizes the various layers observed at Test Pit 3.

Table 3 - Test Pit 3 Observations

0 - 10 cm Concrete slab

10 - 12 cm Void

12 - 58 cm Mixture of sandy silt and large gravel and masonry fragments

58 - 68 cm “Red” plaster floor slab

68 - 86 cm Clay mixed with gravel and masonry fragments

86 - 96 cm “White” plaster floor slab

96 - 100 cm (Bottom of excavation) Clay

American Legation, Tangier, Morocco 42 Final Report September 30, 2014

Figure 46. The perpendicular clay tile wall (red arrow) and floor level (white arrow) from a previous construction.

There were voids in the soil along the sides of the excavation. These voids extended under the unexcavated portions of the floor and did not appear to have been caused by the excavation.

The south exterior wall of Pavilion Arabe at this location is constructed similar to that encountered at Test

Pit 2, with a nonstructural wall located to the interior of the structural wall. The nonstructural wall is about

10 cm thick plus a layer of plaster on the interior face. There is a gap of about 4 cm between the nonstructural wall and the structural wall that is partially filled with grout, as shown in Figure 47.

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Figure 47. View looking upward at nonstructural wall placed on top of finish floor and gap between nonstructural wall and structural wall (red arrow) and void at the base of the structural wall (white arrow)

The depth of the foundation under the structural wall could not be determined since the condition of the foundation material was severely deteriorated. A portion of the face of the footing was covered with plaster and there was a large area at a depth of about 40 cm from the finish floor that was a mixture of soil and gravel rather that part of the foundation. There is also a void in the footing near the finish floor elevation at one edge of the excavation. This void extends upward at an angle into the base of the structural wall for a distance of at least 60 cm. See Figures 47 and 48. Within this void, there are loose fragments of masonry with little or no mortar binding them together. Some of these fragments could be removed by hand.

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Figure 48. Looking upward into void in structural exterior wall with loose masonry fragments

Roof and Terrace Investigation

Inspection of damaged roofing at second floor of Pavilion Arabe

The second floor structure of the Pavilion Arabe as viewed from the underside is composed a metal beam brick arch system for a portion of the floor and a wood framing system for a portion of the floor. The metal beam brick arch system is above rooms 162 and 163 and is exposed (Figure 49). Above room 161 shallow wood joists (6.4 by 10.8 cm) that are spaced at 15 to 16 cm on center span in both directions and are supported by a system of wood girders that are 16.5 by 24 cm (Figure 50).

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Figure 49. View looking southward into room 163 on the first level of the

Pavilion Arabe.

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Figure 50. View looking westward into room 161. The wood framing is a key decorative element of the room.

The roof structure of the Pavilion Arabe as viewed from the underside of the second floor is also composed of shallow wood joists of the same size and spacing as the floor below. These joists run in the east-west direction above room 263 and in the north-south direction above room 262 (Figure 51). The wood framing structure above room 261 is framed similarly to that above room 161 (Figure 52). All wood framing supports a wood subfloor of boards that are about 7.5 cm wide and are oriented perpendicularly to the joists.

The joists and girders of both floors have simple decorative grooves along their length that add character to the aesthetic composition of the exposed and painted wood ceiling system.

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Figure 51. View looking southward into room 263 showing the exposed wood joist ceiling (photo from 2010).

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Figure 52. View of the ceiling in room 261. Like the room directly below the wood framing is a key decorative element of the room.

There is a terrace on the roof of the Pavilion Arabe that is north of and adjacent to the third floor apartment.

This pedestrian terrace roof has a quarry tile walking surface that has been laid on a concrete slab that was poured over the roof wood framing structure (Figure 53). Sometime between 2010 and the time of our 2013 site visit, the roof had been coated with a deck coating (Figure 54) that obscured the quarry tile and limited our ability to perform intrusive inspections of the roof framing from above.

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Figure 53. View looking eastward across the Pavilion Arabe terrace as it appeared in 2010. The terrace was covered with quarry tile and the settlement cracks in the east parapet can be clearly seen.

Figure 54. View looking eastward across the Pavilion Arabe terrace as it appeared in 2013. The terrace has been coated with a deck coating.

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It was observed that the window wall on the north wall of the Pavilion Arabe at both the first and second floors had been added inboard of the columns and arcades on the north side of the building and that rooms

162 and 262 were once exposed to the outside. It was also observed that the north-south oriented wooden girders supporting the second floor had been reinforced with sister joists that were 7.5 x 24 cm and also decoratively grooved (Figure 55). The masonry corbels in the wall that supported the girders were extended to support the sister joist as well (Figure 56).

Figure 55. View looking upward at one of the first floor girders. The “sister” can be seen toward the bottom (arrow). Also note the decorative beads that have been scribed onto the bottom of the girders and joists.

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Figure 56. The corbel that supports the sistered girder (arrow) has also been extended to support the sister.

Active fungal decay of the wood ceiling was observed above room 263 in the form of fruiting bodies and…