Amendment Attachment 3 -- Soils Report.pdf

DECEMBER 2016

VA NCA NATIONAL CEMETERY

JBSA-FORT SAM HOUSTON, TEXAS

GRAVESITE EXPANSION AND

CEMETERY IMPROVEMENTS

FOUNDATION AND PAVEMENT DESIGN ANALYSIS

PREPARED BY

U.S. ARMY CORPS OF ENGINEERS

FORT WORTH DISTRICT

ENGINEERING AND CONSTRUCTION DIVISION

GEOTECHNICAL BRANCH

CESWF-EC-G

JBSA-FORT SAM HOUSTON

FORT SAM HOUSTON NATIONAL CEMETERY

GRAVESITE EXPANSION AND CEMETERY IMPROVEMENTS

FOUNDATION AND PAVEMENT DESIGN ANALYSIS

1. General. The purpose of this report is to provide subsurface information and foundation and pavement design recommendations for a new Gravesite Expansion and Cemetery

Improvements project at the Fort Sam Houston National Cemetery, JBSA-Fort Sam Houston, Texas.

The project solicitation will consist of a Base Bid and five (5) Bid Options. The Base

Bid Based includes addition of approximately 10,427 cremains sites, 3,412 pre-placed burial crypts, and a new Columbarium to accommodate 2,832 burial niches and a Memorial Wall.

The new columbarium and memorial wall will be located northeast of the intersection of

Fredericksburg Street and Victoria Avenue. New pavement structures associated with the Base

Bid items includes a new asphalt extension of Victoria Avenue; the expanded road will extend

Victoria Avenue west to the irrigation pond access road. A new asphalt turn-out lane will be provided for the new Columbarium and Memorial wall.

The following Bid Options will be included in the project solicitation. Bid Option 1 consists of repairs to existing Columbaria. The Customer has noted multiple existing columbaria which are leaning out of plumb and has requested these features be restored to plumb. Specific details regarding the mode of repair to make these corrections are still being discussed with the Customer at the time of this report.

Bid Option 2 consists of providing a new asphalt access road connecting Rittiman Road and Winans Road. It is the understanding of CESWF-EC-G that this bid option is now (at the time of this report) a full project requirement which is planned to be executed through a

Design-Build acquisition contract. This report includes a minimum flexible pavement section to be used for the Design-Build contract.

Bid Option 3 consists of construction of a new approximately 600 GSF Bulk Material

Storage Building which shall be located immediately north of the existing storage building in the facility maintenance building storage yard. The structure is anticipated to be of similar construction to the existing storage building, and include concrete walls up to 10 feet high and a sloping metal roof system; the structure is anticipated to be open on one side to permit storage and removal of bulk materials using a small front-end loader or similar equipment. A section of new concrete pavement (hardstand/apron) adjoining the new building also will be required under this bid option.

Bid Option 4 consists of construction of a new approximately 2,280 GSF 3-Bay

Equipment Storage Building, which is anticipated to be a pre-engineered metal building. A section of new concrete pavement (hardstand/apron) adjoining the new building also will be required under this bid option.

Bid Option 5 consists of replacing panels in the existing ornamental fence along the facility’s northern boundary. No new foundations or pavement features are anticipated to be required for this bid option.

2. Subsurface Investigation. The U.S. Army Corps of Engineers, Fort Worth District, drilled eight (8) test holes at the Fort Sam Houston National Cemetery Gravesite Expansion and

Cemetery Improvements project site in August and October 2016. Specifically, borings 3ST-

1504 through 10A-1526 were drilled at the Gravesite Expansion and Cemetery Improvements project site to determine subsurface conditions and to obtain representative soil and rock samples for laboratory testing. It should be noted that the field investigation originally included a total of twenty-three proposed test holes. However, after an unidentified irrigation line was encountered early in the field investigation, significant schedule and budget impacts following this incident (due to down-time and additional coordination and precautionary measures implemented on the remaining borings) necessitated a re-prioritization of the remaining borings which led to the ultimate reduction in the total borings drilled to eight. Test hole advancement and sample recovery was performed using an 8-inch outer diameter (O.D.)

(4.25-inch inner diameter (I.D.)) hollow stem continuous flight auger, a 4-inch (O.D.) (3.5-inch (I.D.)) continuous inner barrel sampler (sleeve inside hollow stem continuous flight auger), nominal 2-inch and 3-inch (O.D.) split-spoon samplers, and a nominal 3-inch diameter shelby tube sampler. Samples recovered from selective borings were sealed in airtight containers and taken to the laboratory of TEAM Consultants, Incorporated (Arlington, Texas) for testing. Borings at the Fort Sam Houston National Cemetery Gravesite Expansion and

Cemetery Improvements project site were drilled to total depths ranging from 3.0 feet to 28.0 feet below existing grade.

The field investigation was performed using a Gus Pech 1300C truck-mounted drill rig and conventional drilling attachments. Results of the field investigation are shown on the below referenced Civil drawing sheets (Boring Locations) and Sheets B201 and B202 (Logs of

Borings) (Appendix A). The distribution of the borings across the multiple project sub-areas is summarized below.

Boring Borings Project Sub-Area Locations Sheet

3ST-1504 Cremains Expansion Area CE101

3ST-1507 Cremains Expansion Area CE101

3ST-1513 Columbarium and Memorial Wall CE103

3ST-1518 Pre-Placed Burial Crypt Expansion Area CE105

10A-1523 Bid Option 2 Access Road 2CE104

10A-1524 Bid Option 2 Access Road 2CE103

10A-1525 Bid Option 2 Access Road 2CE102

10A-1526 Bid Option 2 Access Road 2CE101

a. Groundwater Conditions. Groundwater conditions were monitored during drilling operations, immediately upon completion of the test holes, and after observation periods of up to 24 hours. Static water levels were measured in one of the eight borings drilled at the

Gravesite Expansion and Cemetery Improvements project site during the investigation.

Specifically, a water level of 23.6 feet below existing grade was measured in boring 3ST-

1513 after an observation period of 17 hours. It should be noted that groundwater conditions are relative to the time of drilling, annual precipitation, and drainage conditions at the site.

b. Dynamic Cone Penetrometer Testing. Dynamic Cone Penetrometer testing (DCP) was performed for pavement design considerations at the Gravesite Expansion and Cemetery

Improvements site in borings 3ST-1513 and 3ST-1518. Results of DCP testing are presented in Appendix D and discussed in paragraphs 4 and 5.

c. Soil Resistivity Testing. A soil resistivity test was performed during the geotechnical field investigation at the approximate location of boring 3ST-1518. The resistivity value measured in the field at this location is 1,388 ohm-cm. Soil resistivity test results are provided in the ‘Remarks’ column of the aforementioned log of boring (Appendix

A).

3. Subsurface Conditions.

a. General Geology. Fort Sam Houston lies within the Balcones fault zone which separates the Edwards plateau province to the northwest from the Gulf Coastal plain province to the southeast. The Balcones zone comprises an area approximately 15 miles wide, trending northeast-southwest through Bexar County. Single faults within this zone exhibit displacements up to 690 feet, with a total displacement across the zone of approximately

1,475 feet.

The primary geologic formation underlying the overburden is assigned to the Taylor

Formation of Upper Cretaceous age. In this area, the Taylor Formation consists of a clay shale which is soft to moderately hard (rock classification), calcareous, slightly silty, with occasional hard, marly zones up to 3 feet thick. The clay shale is generally jointed and weathered to a depth of 50 to 60 feet below ground surface. The Taylor Formation has an estimated thickness of 210 feet in this area and is conformably underlain by the Anacacho

Limestone Formation.

b. Site Conditions. The proposed Gravesite Expansion and Cemetery Improvements project at Fort Sam Houston National Cemetery are located in multiple areas across the facility. All of the areas are grass-covered areas that are generally clear of above-ground features. Most of the project areas have relatively gentle to moderate slopes, with gradients typically between 3 percent and 10 percent. However, the southern approximately one-quarter of the columbarium with ossuary and memorial wall, immediately south of Cemetery Sections

99 and 101, is characterized by gradients between approximately 10 percent and 20 percent. It is within this area that a shallow slope failure occurred in early March 2015, which will need to be repaired prior to constructing the new facilities in this area.

The subsurface conditions described below are based on interpretations of the information presented on the logs of borings and on the results of laboratory testing.

Stratigraphically, the site is characterized by medium to high plasticity clay (CL and

CH, respectively) and clayey sand (SC) overburden soils, interbedded with gravel/cobble overburden strata, and a deeper formation of weathered clay shale primary.

The medium to high plasticity overburden clays are typically very stiff to very hard, dry to moist, yellow brown to brown to dark brown to gray brown, slightly sandy to sandy, slightly silty to silty, slightly gravelly, with iron and magnesium oxide staining. The clayey soils at the locations of borings 3ST-1504 and 3ST-1507 to depths of 2.5 feet and 5.8 feet, respectively, are described as fill materials. Liquid limits measured from representative samples of the medium to high plasticity clay overburden and the seam of clayey sand observed in boring

3ST-1518 (from 10.2 feet to 12.6 feet below existing grade) range from 33 to 69 percent, plastic limits vary from 14 to 25 percent (with plasticity indices ranging from 17 to 45), and in situ moisture contents vary between 12 and 21 percent.

Seams of gravel/cobble overburden are described as dense to very dense, coarse to fine grained, subrounded clasts of limestone and chert, moist to wet, yellow brown to pale brown, slightly sandy to sandy, slightly clayey to clayey, slightly silty, with cobbles up to 6 inches diameter noted (this is believed to be the largest size clast that could be recovered by the augers used during the field investigation).

Beneath the overburden materials a formation of weathered clay shale primary was encountered at a depth of 5.8 feet below existing grade at the location of boring 3ST-1507 and persisted to the total depth investigated (15.0 feet). The weathered clay shale is described as soft (Rock Classification), yellow brown to light gray, friable, silty, and slightly caliched, with iron oxide staining. Although the drilling and sampling methods used made a determination difficult, it is estimated that the weathered clay shale primary is fractured or jointed due to its shallow occurrence and the anticipated depth of short- and long-term in situ moisture variation.

These joints may facilitate the transmission of water, as has been noted during previous geotechnical subsurface investigations performed by the U.S. Army Corps of Engineers, Fort

Worth District, at Fort Sam Houston. Liquid limits measured from representative samples of the weathered clay shale range from 34 to 57 percent, plastic limits vary from 16 to 20 percent

(with plasticity indices ranging from 17 to 37 percent), and in situ moisture contents vary between about 15 and 18 percent. It should be noted that presence of subrounded fine gravel was noted at the base of the boring; as this is not typical of the in situ (non-reworked) clay shale primary elsewhere at Fort Sam Houston, and based on the subsurface strata encountered in the remaining borings (which lack the presence of shallow clay shale primary) the weathered clay shale material observed in this boring may be reworked.

Subsurface conditions representative of the project site are shown on the logs of borings, Sheets B201 and B202. The legend on the individual boring logs show overburden materials as classified in the laboratory using procedures presented in ASTM D 2488. It should be noted that the actual interface between material types may be far more gradual or abrupt than presented; therefore, actual subsurface conditions in areas not sampled may differ from those predicted. The nature and extent of variations across the sites may not become evident until construction commences, and the actual construction process may alter subsurface conditions as well. If variations become evident at the time of construction, CESWF-EC-G should be contacted to determine if the recommendations presented in this report need to be reevaluated.

4. Testing.

a. Laboratory Testing. Representative soil and rock samples recovered from selective test holes were subjected to laboratory testing for identification, moisture content, grain-size distribution, Atterberg limits, density, strength, controlled expansion-consolidation, and permeability. The accumulative test results are tabulated and presented in Appendix C.

Results of identification and moisture content testing are shown on the individual boring logs, Appendix A.

Results of laboratory testing performed on samples obtained from the Gravesite

Expansion and Cemetery Improvements site are presented graphically in Appendix B as follows: Plasticity characteristics are shown on Plate 1, Plasticity Chart. Moisture content values of representative samples are shown with respect to depth on Plate 2. Atterberg limits test results are shown with respect to depth on Plate 3. Dry density values of representative undisturbed samples and their corresponding moisture contents are shown with respect to depth on Plate 4. Ultimate compressive strengths of the clay/clayey sand overburden and clay shale primary are shown with respect to depth on Plate 5.

(1) Shear Strength Testing. Shear strength characteristics of the medium to high plasticity clay and clayey sand overburden and the weathered clay shale primary were analyzed in the laboratory using one-point unconsolidated-undrained triaxial compression testing, confining the specimens to overburden pressure and then loading to failure. Tabulated below are the ultimate compressive strengths and respective dry densities of the clay shale primary specimens. Shear strength test results are also presented in Appendix C at the end of this report.

Boring Depth, feet γd, pcf Qu, tsf Material Type

3ST-1507 9.7 108.3 3.56 Weathered Shale 3ST-1507 14.2 114.4 3.45 Weathered Shale 3ST-1513 5.0 103.0 4.15 CH Clay Overburden 3ST-1513 13.0 107.7 4.33 CL Clay Overburden 3ST-1513 20.5 108.8 4.19 CL Clay Overburden 3ST-1518 2.9 98.2 1.82 CL Clay Overburden 3ST-1518 6.9 100.6 2.97 CL Clay Overburden 3ST-1518 10.9 112.6 3.66 SC Clayey Sand Overburden

(2) Controlled Expansion-Consolidation Testing. Controlled expansion-consolidation (CEC) testing was performed on two specimens of high plasticity clay (CH) overburden, and on one specimen of medium plasticity clay (CL) overburden. The results of the controlled expansion-consolidation testing for these specimens are discussed below and are presented in Appendix C; these data are used in the expansive soils analysis, as discussed in

Paragraph 5.a., below.

Controlled expansion-consolidation testing was performed on a specimen of high plasticity clay (CH) overburden (clay fill) collected at a depth of 4.75 feet within boring 3ST-

1507. This high plasticity clay overburden specimen has a liquid limit of 61 percent, a plastic limit of 23 percent (with corresponding plasticity index (PI) = 38), and natural moisture content of approximately 17 percent. An expansion pressure (pexp) of approximately 1.0 tsf was recorded during CEC testing of this high plasticity clay overburden specimen. Based on

CEC test results, the high plasticity clay overburden specimen collected at a depth of 4.75 feet within boring 3ST-1507 has a moderate to high expansion potential (Cs = 0.057; pexp/p0 = 3.4) and a high consolidation potential (Cc = 0.253). Controlled expansion-consolidation was also performed on a specimen of high plasticity clay (CH) overburden collected at a depth of 5.0 feet within boring 3ST-1513. This high plasticity clay specimen has a liquid limit of 69 percent, a plastic limit of 25 percent (PI = 44), and natural moisture content of approximately

21 percent. An expansion pressure (pexp) of approximately 3.0 tsf was recorded during CEC testing of this high plasticity clay specimen. Based on CEC test results, the high plasticity clay specimen collected at a depth of 5.0 feet within boring 3ST-1513 has a high to very high expansion potential (Cs = 0.061; pexp/p0 = 9.6 and a moderate consolidation potential (Cc =

0.163). Controlled expansion-consolidation was also performed on a specimen of medium plasticity clay (CL) overburden collected at a depth of 13.0 feet within boring 3ST-1513. This medium plasticity clay overburden specimen has a liquid limit of 41 percent, a plastic limit of

18 percent (PI = 23), and a natural moisture content of approximately 18 percent. An expansion pressure (pexp) of approximately 0.75 tsf was recorded during CEC testing on this medium plasticity clay overburden specimen. Based on CEC test results, the medium plasticity clay overburden specimen collected at a depth of 0.75 feet within boring 3ST-1513 has a low to moderate expansion potential (Cs = 0.026; pexp/p0 = 0.9) and a moderate consolidation potential (Cc = 0.136).

Controlled expansion-consolidation test results are summarized below.

Depth, Boring feet LL & PI Pexp Pexp/Po Cs & Cc Material Type

3ST-1507 4.7 61 38 1.0 3.4 0.057 0.253 CH Clay Overburden/Fill 3ST-1513 5.0 69 25 3.0 9.6 0.061 0.163 CH Clay Overburden 3ST-1513 13.0 41 23 0.75 0.9 0.026 0.136 CL Clay Overburden

(3) Permeability Testing. Laboratory coefficient of permeability testing was conducted in accordance with EM 1110-2-1906, Appendix VII. Laboratory permeability testing was performed on two undisturbed specimens of medium plasticity clay (CL) overburden and on one undisturbed specimen of clayey sand (SC) overburden. A coefficient of permeability (k) of 1.38 x 10-6 cm/sec (approximately 2.72 x 10-6 ft/min) was measured in a specimen of medium plasticity clay overburden collected at a depth of approximately 2.9 feet within boring 3ST-1518. A coefficient of permeability (k) of 1.01 x 10-6 cm/sec

(approximately 1.99 x 10-6 ft/min) was measured in a specimen of medium plasticity clay overburden collected at a depth of approximately 6.9 feet within boring 3ST-1518. A coefficient of permeability (k) of 1.41 x 10-6 cm/sec (approximately 2.78 x 10-6 ft/min) was measured in a specimen of clayey sand overburden collected at a depth of approximately 10.9 feet within boring 3ST-1518. The laboratory permeability testing results demonstrate the very low permeability of the clayey overburden materials.

b. Field Testing. Dynamic Cone Penetrometer (DCP) testing was performed for pavement design considerations at the Gravesite Expansion and Cemetery Improvements site in borings 3ST-1513 and 3ST-1518. A DCP consists of a steel rod with a steel cone attached to one end and a sliding single-mass hammer. For this project, the DCP test was performed by driving the steel cone into the soil using a 10.1-pound sliding hammer dropped from a height of 22.6 inches (574 millimeters). The number of blows required for each 0.4 inch (10-

mm) or higher of penetration was recorded as the "penetration per blow set"; therefore, the more penetration achieved per blow indicates that a "weaker" soil layer was encountered.

Typically, penetration measurements are taken to a depth of 39.4 inches (1,000 millimeters) or when refusal is achieved. Refusal is defined as the point when the cone cannot penetrate the soil more than 0.4 inches (10 millimeters). Presented below are the average in situ strength parameters derived from the DCP tests. DCP test results are also presented in

Appendix D at the end of this report.

Depth, in CBR, % k, pci

0 – 6 6 - 8 142 - 171 6 – 12 5 - 6 127 - 145 >12 4 - 6 113 - 143

5. Discussions. The following discussions are provided in support of the foundation and pavement design recommendations made for the proposed Gravesite Expansion and Cemetery

Improvements.

a. Soil Activity Considerations. The Gravesite Expansion and Cemetery Improvements project site is characterized by medium to high plasticity clay (CL and CH, respectively) and clayey sand (SC) overburden soils, interbedded with gravel/cobble overburden strata, and a deeper formation of weathered clay shale primary. Liquid limits measured from representative samples of the medium to high plasticity clay and clayey sand overburden range from 33 to 69 percent, plastic limits vary from 14 to 25 percent (with plasticity indices ranging from 19 to

45), and in situ moisture contents vary between 12 and 21 percent. The weathered clay shale primary, encountered at a depth of 5.8 feet below existing grade at the location of boring 3ST-

1507, has liquid limits ranging from 34 to 57 percent, plastic limits ranging from 16 to 20 percent (with plasticity indices varying from 17 to 37), and in situ moisture contents ranging from 15 to 18 percent. The plasticity characteristics and in situ moisture contents of the high plasticity overburden clay soils and the weathered and unweathered clay shale primary are summarized in the table below.

Range of Atterberg Limits and In Situ Moisture Contents Measured at the

Gravesite Expansion and Cemetery Improvements Project Site

Stratum LL, % PL, % __PI__ w, %

CL/CH Clay and SC Overburden 33 – 69 14 – 25 19 – 45 12 – 21 Weathered Clay Shale 34 – 57 16 – 20 17 – 37 15 – 18

Moisture content and Atterberg limits test results indicate that these materials are potentially moisture deficient throughout the entire depth investigated (28.0 feet).

The results of controlled expansion-consolidation testing conducted on specimens collected during the geotechnical field investigation at the Gravesite Expansion and Cemetery

Improvements project site are discussed in detail in paragraph 4.a.(2), above. Based on the controlled expansion-consolidation testing, the medium to high plasticity overburden clay and clay fill soil within approximately the upper 7 feet with respect to existing grade has a moderate to very high potential for expansion, and the medium plasticity clay overburden below approximately 7 feet has a low to moderate potential for expansion. Also, based on the cited testing data, the medium to high plasticity overburden clay and clay fill soil within approximately the upper 7 feet with respect to existing grade has a moderate to high potential for consolidation (particularly the clayey fill materials), and the medium plasticity clay overburden below approximately 7 feet has a moderate potential for consolidation.

An expansive soils analysis was performed to quantify the response of the active clayey overburden/fill soil when subjected to increased load conditions during periods of seasonal moisture fluctuations. Analyses were also performed to estimate the magnitude of settlement that may be anticipated of the medium to high plasticity clay overburden and fill materials. In the analysis, the clayey overburden and fill materials are assumed to be in a saturated condition, and initially, surcharge loads (additional fill and building) were neglected. The expansive soils analysis for slab-on-grade design considerations (heave and settlement) is based on the following material properties, by layer/depth interval:

Depth, feet LL & PI Pexp, tsf Pexp/Po Cs & Cc Material Type

0.0 – 3.0 61 38 1.0 3.4 0.057 0.253 CH Clay Overburden/Fill1

3.0 – 7.0 69 44 3.0 9.6 0.061 0.163 CH Clay Overburden 2

7.0 – 25.0 41 23 0.75 0.9 0.026 0.136 CL Clay Overburden 3

1. Boring 3ST-1507, specimen ST-1 (sample depth = 4.7 feet) – this investigation;

2. Boring 3ST-1513, specimen ST-1 (sample depth = 5.0 feet) – this investigation;

3. Boring 3ST-1513, specimen ST-2 (sample depth = 13.0 feet) – this investigation.

Based on an analysis of the Atterberg limits and moisture content laboratory testing data, the active zone is anticipated to potentially extend to at least 25 feet below existing grade. Based on these conditions the heave potential of the medium to high plasticity clay overburden soil and clayey fill materials was determined to be approximately 3.2 inches.

Considering a building surcharge loading of 100 psf, the heave potential was determined to be approximately 2.7 inches. Considering a building surcharge loading of 100 psf and surcharge loadings due to additional fill placed for site grading purposes and ranging from 1 to 5 feet in height above existing grade, the heave potential was determined to range from approximately

2.4 to 1.6 inches (with decreasing heave potential with increasing surcharge load).

Considering a continuous spread footing loading allowable bearing pressure of 2,000 psf, the heave potential was determined to be less than 1 inch.

The compressibility characteristics of the medium to high plasticity clay overburden soil and clayey fill materials were evaluated using the controlled expansion-consolidation

(CEC) testing data presented above. Considering a building surcharge load of 100 psf, the settlement potential of the medium to high plasticity clay overburden soil and clayey fill materials is anticipated to be approximately 0.9-inch. Considering a building surcharge loading of 100 psf and surcharge loadings due to additional fill placed for site grading purposes and ranging from 1 to 5 feet in height above existing grade, the settlement potential was determined to range from approximately 1.7 to 3.7 inches. Considering a continuous spread footing loading allowable bearing pressure of 2,000 psf, the settlement potential was determined to be approximately 6.4 inches. Considering a continuous spread footing loading allowable bearing pressure of 2,000 psf and surcharge loadings due to additional fill placed for site grading purposes and ranging from 1 to 5 feet in height above existing grade, the settlement potential was determined to range from 6.6 inches to 7.3 inches. Fill surcharges exceeding 5 feet are not anticipated, however settlement potentials for greater fill surcharges can be provided by CESWF-EC-G upon request.

The expansive soils analysis demonstrates the high expansion and consolidation potential of the medium to high plasticity clay overburden soil and clayey fill materials. Due to the potential high volumetric changes that may be expected of these highly plastic materials, special foundation, floor slab, and subgrade preparation requirements for the Gravesite

Expansion and Cemetery Improvements are provided herein to withstand the effects of the highly expansive and compressible subsurface conditions.

b. Foundation Design Considerations. The foundation design recommendations presented in this report are based on criteria contained in TM 5-818-1, TM 5-818-7, and engineering judgment.

The foundation for the proposed facility must meet several criteria. It must be compatible with the superstructure it supports, its movements must be within acceptable tolerances, it must meet functional requirements of the facility (such as a crawlspace, if used), and it must be economical. For this project, the primary structures requiring foundation designs include the columbaria, the memorial wall (and other retaining walls for the project), the Equipment Storage Building, and the Bulk Material Storage Building. Based on information available at the time of this report, the columbaria will be approximately 10 feet in height above-ground, with approximately 3 feet of structure below grade (above the foundation). As previously discussed, both the Equipment Storage Building and the Bulk

Material Storage Building are anticipated to be small to very small single-story structures.

A deep foundation system, such as reinforced concrete drilled piers or pre-cast concrete driven piles, is not considered necessary to support the project structures based on the anticipated relatively light loading conditions. Furthermore, based upon the results of laboratory strength testing, there is no benefit to using a deep foundation system, as the relatively low to moderate shear strength of the clay overburden materials and clay shale primary does not appear to increase significantly with depth. Alternatively, a shallow foundation system, such as reinforced concrete continuous spread footings bearing on compacted nonexpansive fill is considered to be well-suited to support the proposed project structures. A reinforced concrete continuous spread footing foundation system would have the benefit of being able to be constructed above the anticipated ground water level (estimated to be within one of the gravel/cobble layers well below the anticipated footing depth in the immediate area of the new columbaria). Using a network of connected reinforced concrete continuous spread footings, bearing on compacted nonexpansive fill, to support the columbaria

(and retaining walls, where used), will help to limit the differential movement (heave and settlement) of the structures compared to an isolated spot spread footing foundation system.

Foundation design recommendations and requirements are provided in Section 6.a., below.

c. Pavement Design Considerations. The pavement designs presented in this report are based on criteria contained in UFC 3-250-01FA, TM 5-822-2, and engineering judgment.

(1) Traffic Types and Conditions. Four (4) pavement structures were analyzed and designed for this project. Specifically, new rigid pavement structures include an apron replacement around the Equipment Storage Building and Bulk Material Storage Building (Bid

Options 3 and 4). Types of vehicles anticipated to utilize the apron include light- to medium-duty Government-owned Vehicles (GOVs) (passenger cars and trucks) (Category II Traffic), large mult-axle trucks (Category IVA Traffic), and fork-lift traffic making infrequent passes

(fewer than 25 per hour) (Class F Street), as well as other maintenance vehicles/equipment

(such as small front-end loaders, etc.); a pavement Design Index equal to 4 is assigned to this pavement area (the design section is upgraded to account for uncertainties in maintenance vehicle types and pass frequencies). A rigid pavement section (option) is also provided for the

Victoria Avenue extension and for service/access drives (to include Columbarium turn-out lanes which may be used by larger truck traffic); the design is based on large multi-axle truck traffic (Category IVA Traffic) governing, making fewer than 25 passes per hour (Class F

Street), resulting in a pavement Design Index equal to 4. New flexible pavement structures include the Victoria Avenue extension and service/access drives (flexible pavement option) and privately-owned vehicle (POV)/GOV parking areas (to include Columbarium turn-out lanes that will be used only by light- to medium-duty passenger cars and trucks). Per above discussion, the Victoria Avenue extension and service/access drives pavement design is based on a pavement Design Index equal to 4. The POV/GOV parking areas pavement design is based on Category II Traffic making at least 250 passes per hour, but fewer than 750 passes per hour) (Class D Street), for a pavement Design Index equal to 2. A minimum flexible pavement section is also included herein for use by the Design-Build contractor for the Rittiman Road-

Winans Road access road. The minimum pavement design is based on large multi-axle truck traffic (Category IVA Traffic) making at least 25 passes per hour but fewer than 250 passes per hour (Class E Street) for a pavement Design Index equal to 5. An aggregate surfaced minimum pavement design is also included for the Rittiman Road-Winans Road access road. Based on criteria contained in the aforementioned United Facilities Criteria and the discussions above, the following traffic conditions are assigned:

Pavement Structure Traffic Category Street Class Design Index

Aprons (Maintenance Yard) IVA F 4 Victoria Ave. Ext./Service/Access Drives IVA F 4 POV/GOV Parking Areas II D 2 Rittiman Rd.-Winans Rd. Access Drive IVA E 5

(2) Pavement Design Parameters. California Bearing Ratio (CBR) and plate bearing tests were not performed for this project. Instead, dynamic cone penetrometer (DCP) testing was conducted to evaluate the raw subgrade for pavement design considerations. The penetration resistance obtained from the DCP test is a measure of the soil’s relative density, which in turn is used to derive “in situ” CBR and modulus of subgrade reaction values.

The average in situ CBR values measured within the upper 12 inches of soils tested at the Gravesite Expansion and Cemetery Improvements site range from approximately 5 to 8 percent, and below this depth, CBR values ranging from 4 to 6 percent were recorded.

Modulus of subgrade reaction values measured within the upper 12 inches of soils tested range from 127 to 171 pci, and below this depth, modulus of subgrade reaction values ranging from

113 to 143 pci were recorded. In the past, the high plasticity clay subgrade indicative of Fort

Sam Houston has been assigned CBR values ranging from 5 to 7 percent when compacted to 95 percent of laboratory maximum density, and 3 to 4 when compacted to 90 percent of laboratory maximum density. Previously conducted plate-bearing tests indicate that modulus of subgrade reaction values on the order of 75 pci to 125 pci can be assigned to the in situ soils when compacted to 90 percent and 95 percent, respectively, of laboratory maximum density. The

CBR and subgrade modulus values determined from in situ DCP testing are variable and generally consistent with the historical CBR and subgrade modulus values described above.

Based on these considerations, and considering that some of the pavement structures may be constructed on new fill placed for site grading purposes, design CBR and modulus of subgrade reaction values of 4 percent and 100 pci, respectively, were assigned to the raw subgrade when compacted to 90 percent of laboratory maximum density (ASTM D 1557).

(3) Lime Stabilization. Atterberg limits test results indicate that the clay overburden and clayey fill are moderately to highly expansive. A layer of lime-stabilized subgrade is typically recommended to improve the strength characteristics of pavement sections at Fort Sam Houston. Existing pavement structures at Brooke Army Medical Center

(SAMMC-North) incorporate lime-stabilized subgrade layers and have achieved excellent performance. Therefore, lime stabilization is recommended for new pavement structures.

(4) Material Sources. Material sources in the San Antonio area are capable of producing a high quality crushed aggregate for concrete mixes to meet strength requirements.

For this reason, a concrete flexural strength of 650 psi at 28 days was considered in the design of rigid pavements. To date, Alkali/Silica Reaction with Portland Cement Concrete has never been a problem when using local aggregate sources.

6. Recommendations. The following foundation and pavement design recommendations are based on results of the field investigation, laboratory testing, and engineering analyses and judgement.

a. Foundation Design Recommendations.

(1) Foundation System.

(a) Continuous Spread Footings (Columbarium and Memorial Wall).

The Columbarium structures and Memorial Wall can be supported on a foundation system consisting of dug and formed reinforced concrete continuous spread footings. Isolated spot footings are not recommended due to potential differential settlement or heave of the clay overburden and clay shale primary. The continuous footings should be should bear at least 3.0 feet below existing grade, if permitted by site grading requirements, however the footings should bear a minimum of 24 inches below outside finish grade. The existing soils to a depth of 4.0 feet below existing grade or a minimum of 2.0 feet below the base of the footings, whichever is deeper, should be excavated and replaced by nonexpansive fill which shall be placed below the base of the footings in controlled lifts not exceeding 8 inches in loose thickness and compacted to at least 95 percent of maximum laboratory density as determined in accordance with ASTM D 1557. The footings should be sized for an allowable bearing pressure (qall) of 2.0 ksf. This allowable bearing capacity is assigned based on the results of laboratory strength testing and controlled expansion-consolidation testing (analyzing potential differential heave and settlement for a range of allowable bearing pressures). Based on the results of the settlement analyses, total and differential settlements should be held to approximately 1 inch or less when incorporating the foundation and subgrade preparation recommendations provided herein. The load used to size the footings should consist of full dead load plus that portion of the live load that acts more or less continuously, usually 50 percent. Load-carrying masonry walls (if used) should be supported on a minimum 18-inch wide continuous footing founded as stated above. Non-load bearing masonry walls (partitions;

if used) can be placed on a minimum 12-inch wide “shovel beam” footing.

It is recommended that minimum ½-inch expansion joints (full height through the structure) be incorporated to prevent differential movements from impacting adjoining sections of the columbarium structures.

(b) Reinforced Concrete Ribbed Mat Slab and Reinforced Concrete Flat

Mat Slab (Equipment Storage Building). It is recommended that the proposed Equipment

Storage Building be supported on either a reinforced concrete ribbed mat slab or flat mat slab foundation system. The mat slab shall be conventionally reinforced – POST-TENSIONED

SLABS ARE NOT ALLOWED. Based on the plasticity level of the near surface clayey and gravelly soils, the mat slab shall be analyzed and designed for approximately 1.0 inch of long-term differential movement. For this reason, interior ribs for ribbed mat slabs shall be spaced no further than 20.0 feet center-to-center, and diagonal stiffener ribs shall be placed at each corner of the mat slab. Design of the mat slab shall meet the minimum requirements as presented in CESWD-ED-TS/G Criteria Letter, dated 29 January 1988 – Design Criteria for

Ribbed Mat Foundations, SWDED-G Criteria Letter, dated 16 April 1987 – Criteria for

Developing Geotechnical Design Parameters for SWD Ribbed Mat Design Methodology, and the recommendations and requirements provided herein.

Interior and exterior beams for ribbed mat slab should bottom a minimum of 24 inches below outside finished grade. An allowable bearing capacity of 2.0 ksf (net) shall be used to size the beams. For this phase of design, it should be noted that (1) the structural load is supported solely on the beam and the beam intersections, (2) load transfer occurs over the effective beam width, and (3) the beam and soil remain in contact. Beam intersections should be widened at column locations to accommodate the above allowable bearing value for the anticipated load condition. The load used to size the beams shall consist of full dead load plus that portion of the live load that acts more or less continuously, usually 50 percent.

The ribbed mat slab foundation shall incorporate adequate stiffness such that the deformations do not exceed the structural tolerance of any elements in the foundation or superstructure. Analyses shall consider a vertical separation of the foundation slab and beams from the subgrade of 1.0 inch at the outside of all perimeter beams, with loss of support beneath the foundation over a horizontal distance of not less than 6.5 feet. This loss of support condition corresponds to the center lift mode. Additionally, edge lift analyses shall consider an edge moisture variation distance equal to 3.0 feet, and an edge lift heave of 1.0 inch should be used in the design of the ribbed mat slab. This edge lift heave corresponds to an applied structural pressure of 100 psf. For edge lift considerations, two additional combinations of pressure and swell are required. For an allowable bearing capacity of 2.0 ksf, an edge lift heave of 0.75-inch can be expected to occur. At an ultimate bearing capacity of 6.0 ksf, 0.50-inch of heave should be anticipated. It should be noted that these anticipated heave amounts are based on the removal of a minimum of 4.0 feet of existing materials under building floor slab and replacement with compacted nonexpansive fill, as required herein.

A modulus of subgrade reaction equal to 200 psi/inch shall be used when analyzing the ribbed mat slabs to determine in-service deformations. This value, however, shall be factored to account for width effects such that kdesign=k1/(Beff), where Beff is the effective beam width in feet. Design of the ribbed mat slabs may use the SWD-AEIM sections as a minimum stiffness

"first approximation".

A flat mat shall have a uniform thickness of not less than 18 inches. An allowable bearing capacity of 2.0 ksf (net) shall be used to size the mat foundation. The mat should be tapered as required to ensure the perimeter of the slab extends to a constant elevation and is at least 18 inches below outside finish grade. The flat mat slab shall incorporate adequate stiffness such that the deformations do not exceed the structural tolerance of any element of the foundations or superstructures nor cosmetic cracking of interior and exterior finishes. Control joints/panels shall be incorporated within interior finishes and exterior facades to help control potential cracking due to slab movements. The load used to size the flat mat slab shall consist of full dead load plus that portion of the live load that acts more or less continuously, usually

50 percent.

The mat slab will, by design, be supported on-grade. A polyethylene vapor barrier

(10-mil minimum thickness) and a minimum 6-inch capillary water barrier should be placed beneath the mat slab.

(c) Bulk Material Storage Building and Small Support-type Structures.

The Bulk Material Storage Building and small (<500 GSF) support-type structures (if used) can be supported on a reinforced concrete slab-on-grade with turned-down edge beam foundation.

The turned-down edge beam should extend a minimum of 12 inches below outside finished grade, and can be sized for a safe bearing pressure of 2,000 psf (net). Subgrade preparation shall be in accordance with that specified in Paragraph 6.a.(3)(b) for mat slab construction.

(2) Ground-Level Floor Slab System. The mat slab systems will, by design, be supported on-grade.

(3) Subgrade Preparation and Fill Requirements.

(a) Continuous Spread Footings. The existing soils within the continuous spread footing foundation footprint shall be removed to a depth of 4.0 feet

(minimum) or to a minimum of 2.0 feet below the base of the footings, whichever is deeper, and shall be replaced with compacted nonexpansive backfill which should limit the magnitude of predicted movement to approximately 1 inch or less. Any additional fill required to achieve the final subgrade elevation shall be nonexpansive material as well. The upper 6 inches of existing subgrade exposed after excavation operations, or cleared prior to fill placement shall be scarified, moistened, manipulated, and recompacted to the same density required for nonexpansive fill materials. Nonexpansive fill shall be placed in controlled lifts not exceeding

8 inches in loose thickness and compacted to at least 95 percent of laboratory maximum density in accordance with ASTM D 1557.

(b) Reinforced Concrete Ribbed or Flat Mat Slab. For ribbed or flat mat foundations, the upper 4.0 feet (minimum) of existing soils within the building footprint shall be removed and replaced with compacted nonexpansive backfill, and a minimum of 2.5 feet of compacted nonexpansive fill shall be placed immediately beneath the mat slab, whichever is

GREATER, which should limit the magnitude of predicted movement to approximately 1 inch or less. Any additional fill required to achieve the final subgrade elevation below the floor slab system shall be nonexpansive material as well. The upper 6 inches of existing subgrade exposed after excavation operations, or cleared prior to fill placement shall be scarified, moistened, manipulated, and recompacted to the same density required for nonexpansive fill materials. Nonexpansive fill shall be placed in controlled lifts not exceeding 8 inches in loose thickness and compacted to at least 95 percent of laboratory maximum density (in accordance with ASTM D 1557).

Based on previous experience, if nonexpansive fill is placed outside the limits of the building footprint, the relatively higher permeability of the nonexpansive fill will allow moisture to infiltrate to the highly expansive soils adjacent to and beneath the foundation, potentially resulting in heave of the foundation. To limit moisture penetration to the area around and beneath the foundation, excavated areas beyond the limits of the building footprint shall be backfilled with select clay backfill materials. This select clay cap shall be a minimum of 2 feet in thickness and shall extend from the building perimeter to the limits of the excavation (completely capping/covering the compacted nonexpansive fill). Select clay backfill materials should be compacted to at least 92 percent of laboratory maximum density

(with all other subgrade preparation and fill placement requirements being the same as those for nonexpansive fill).

(4) Below-Grade Structures (Including Retaining Walls). The following parameters are provided for the design of all below-grade structures, including retaining walls.

For the high plasticity clay and weathered clay shale, an at-rest lateral earth pressure coefficient (Ko) of 0.7, an active earth pressure coefficient (Ka) of 0.7 (a passive earth pressure coefficient, Kp = 1.4), an angle of internal friction (φ) of 10o, a cohesion value (c) of 100 psf, a coefficient of friction to resist sliding, µ= 0.18, and an allowable bearing capacity of 2,000 psf shall be used. For cohesionless granular backfill placed behind retaining wall(s), an angle of internal friction (φ) of 30o should be used. The clay, clay shale, and backfill material should be assumed to have a moist unit weight of 125 lb/ft3. All backfill shall be nonexpansive or select material. Retaining wall analyses and designs shall also account for surcharge loadings (e.g., due to vehicular traffic) where applicable. Retaining wall designs shall incorporate drainage features, to include granular drains, seepage collector pipes, weep holes, etc., as detailed in the

SWD AEIM.

(5) Drainage. Proper drainage is an important design consideration to ensure satisfactory long-term foundation performance. Exterior grading adjacent to buildings should be sloped away from the structure a minimum of 5 percent for the first 10 feet. Runoff from the roofs should be adequately discharged away from foundation edges. In no case should water be allowed to pond adjacent to or beneath the buildings, both during and after construction.

(6) Care of Water. Drainage of ground and surface water from the project site continually throughout the construction contract is essential. The contractor shall be required to protect the excavations and all constructed work throughout the life of the contract by means of ditches, berms, sumps with pumps, and any other means required to continually and effectively remove water from the site at all times. Ponding of water in excavations is unacceptable at any time. In addition, site excavations to include utility trenching, grading, and retention basins (if used) shall be constructed so as not to supply water directly or indirectly to the building or underlying active clay shale via the pervious gravel stratum. Such exposure of the underlying clay shale primary to surface runoff during construction could extend the active zone (via fractures) to much greater depths within the clay shale. This would activate these highly expansive materials and result in expansion pressures on the foundation elements that could create distress on the structural system of the facility. These requirements shall be reflected in the specifications and in the structural notes.

The designer shall grade the site to ensure positive drainage of all water away from the structures.

(7) Stormwater Management Area(s). Stormwater management (detention) areas, or any other feature designed to permanently or temporarily impound water, if required, shall not be located near buildings (a minimum 50-foot separation is recommended). Such features will ultimately serve to feed water into the extremely expansive substrate and induce heave upon the nearby building foundation(s). For this reason, stormwater management areas also shall not be situated immediately adjacent to pavement structures (a minimum 15-foot separation is recommended). If such a feature must be constructed near a building or pavement structure, CESWF-EC-G shall be notified and shall provide additional recommendations for measures to ensure water is not permitted to infiltrate into the highly expansive substrate.

(8) Mechanical Connections. All exterior mechanical connections should be of the flexible type. Flexible connections should be capable of resisting a minimum of 4 inches of both vertical and horizontal movement. All mechanical/structural connections between slabs on grade and structurally supported units or building perimeter entry/exit points must be designed and constructed to handle up to 4 inches of vertical movement. All condensate lines should drain away from foundation edges.