May 2010 Progress Report

PROGRESS REPORT: May 20, 2010

MISSION SAN XAVIER del BAC: Period: 03.20.10  – 05.20.10

SUBMITTED TO THE PATRONATO SAN XAVIER BY BOB VINT, ARCHITECT         TUCSON, AZ

STABILIZATION:  SACRISTY ARCADE

Site Visits & Meetings of    3.19.10, 4.16.10; 4.30.10; 5.12.10; and 5.19.10

(A.1)    3.19.10    SITE MEETING (9:00 a.m., 65º, partial clouds)

PRESENT:      B. Vint, D. Morales, MRB crew [Sonny, Vince, Jorge, Santiago, Freddy, Alex]

WORK IN PROGRESS: Removal of cement plaster from base of piers at arcade.

DISCUSSED:    Base of piers to height of 4 ft. above grade is built of a mixture of rubble burned brick and stone masonry.  Above the 4 ft. level the arcade is built of unfired mud adobe at the wall and arches.  The question was asked, why was a mixture of brick and stone used at the pier bases? It’s good practice to use a relatively stronger material at the base of the piers carrying the weight of the adobe arches and wall above. It’s possible that the stone and burned brick used – a collection of broken and irregular shapes and sizes – was left over from the construction of the Mission church.

 

(A.2)    4.6.10    SITE MEETING (10:00 a.m., 65º, clear)

 

PRESENT:      B. Vint, D. Morales, MRB crew [Santiago Gomez, Freddy Garcia, Jorge Gomez, Vincent & Sonny Morales]

 

WORK IN PROGRESS: Continued removal of cement plaster from arcade piers. Deterioration of brick is extensive beneath rainwater sluices, which were installed in the 1950s using cement plaster.

 

DISCUSSED: Need final decision on how to handle rainwater run-off from roof  – whether to bring water down surface of pier in sluice to match Mission church, or use canales as was done at Convento wing and arcade in 19th century, per historic period photos.  Bob favors continuing use of bajadas de agua  [sluices] for aesthetic continuity with church.  As they are re-built using lime they will not trap moisture like cement.

 

(A.3)    4.16.10    SITE MEETING (9:15 a.m., 55º, partial high clouds)

 

PRESENT:      B. Vint, D. Morales, David & Quintana Carter, MRB crew [Santi Gomez, Fred Garcia, Jorge Gomez, Alex Tracy, Vincent & Sonny Morales]

 

WORK IN PROGRESS: Continued cement plaster removal at piers including rain sluices; commencing excavation at bases of piers to investigate foundation conditions.

 

DISCUSSED: Carter suggested alternative to rain sluices, as seen at the recently restored sister Mission of La Purísima Concepción de Caborca, Sonora [visited by Bob and David on  SW Mission Research Center tour]: mesquite canales. Vint suggests presenting options to Patronato Board at next full meeting.  Morales reports he can do whatever he is asked to do – he just needs direction. Carter also wondered whether the brick & stone bases of the piers could, or should, be left exposed as they are visually interesting.

 

 

 

(A.4)    4.30.10    SITE MEETING (9:30 a.m., 75º, clear)

 

PRESENT:      B. Vint, D. Morales, MRB crew [Santi Gomez, Fred Garcia, Jorge Gomez, Alex Tracy, Vincent & Sonny Morales]

 

WORK IN PROGRESS: Excavation at base of piers; removal of concrete paving and catch basins; catch basin to be rebuilt of brick & lime to match those at west side of church.

 

DISCUSSED: Location of new piers to support roof and scaffold load.  CMU piers to be centered on historic masonry piers; at SW corner of courtyard, new pier shall align with south wall or courtyard [replaced with CMU at direction of Fr. Michael Dalmeier in the summer of 1994].  Wiring & lighting needs to be “cleaned up” [Danny’s words] and re-fed in rigid conduit to existing electrical sub panel at south end of arcade.  Danny’s preferred electrician, Mountain Skyline, is qualified to do this work. If Danny feels it necessary he will request review by an electrical engineer. It’s a matter of re-feeding existing and removing inactive wires.

 

(A.5)    5.12.10    SITE MEETING (8:15 a.m., 70º, clear)

 

PRESENT:      B. Vint, D. Morales,  MRB crew [Santi Gomez, Fred Garcia, Jorge Gomez, Alex Tracy, Vincent & Sonny Morales]

 

WORK IN PROGRESS: Excavation for foundations of new piers. Vince hand digging to depth of approx. 24” below grade; soil is floury and loose. Pier foundations of rubble stone extend deeper.

 

DISCUSSED:  Danny concerned with depth necessary to place new foundations on solid soil. Q: should  MRB  continue to excavate to depth of old footing?  Elsewhere on church foundations bear on caliche shelf of varying depth. Discussed how deep to dig adjacent to historic footings. MRB will consolidate stone of old footings with lime mortar and install  “lime-crete” barrier along edge of arcade at courtyard to protect from moisture. Vint will invite the geotechnical engineer Ralph Pattison to inspect site and view conditions and advise.

 

(A.6)    5.19.10    SITE MEETING (8:00 a.m., 65º, clear)

 

PRESENT:  B. Vint, D. Morales, Ralph Pattison P.E., MRB crew [Santi Gomez, Fred Garcia, Jorge Gomez, Alex Tracy, Vincent & Sonny Morales]

 

WORK IN PROGRESS:  Excavation for new footings.

 

DISCUSSED: Ralph inspected excavations. His preference is for deeper rather than wider footings, as the deeper one digs, the more firm the soil generally becomes.  If possible a portion of the new footing should bear at the same depth as the historic original. Ralph’s concern is that the new footing may settle differently than the old.  Keeping the soil beneath the footing dry is important:  the consolidated stone and lime-crete barrier proposed by Danny appears to be a good solution for this.  Ralph recommends an extension of the new footing to match the width of the new pier [16”] to the same bearing level as the historic piers. He will submit a brief report with his observations.