PRARNG_Fort_Buchanan_JFHQ_Geotechnical_Report.pdf

The attached is the Geotechnical Investigation Report that was completed in November 2011 for the PRARNG Joint Force Headquarters Project in Fort Buchanan Puerto Rico and shall be considered Supplemental Information Only for the Contractor’s Use. The Contract Plans and Specifications have taken into consideration the discussions and recommendations in the report and govern as construction requirements. The Contractor is required to verify all existing conditions necessary for proper installation, construction, and operation of all elements indicated in, and in accordance with the Contract Documents.

Geotechnical Investigation Report for Proposed Joint Force Headquarters

At Fort Buchanan Guaynabo, Puerto Rico

Job No. 1095

November 9, 2011

Prepared for:

Arch. David Everett Jacobs Engineering Group, Inc.

125 Broadway Ave.

Oak Bridge, TN 37830

Prepared by:

MGV GEOTECHNICAL GROUP, PSC

PO Box 19480

San Juan, PR 00910

G eo te ch n ic al E n g in ee rs -E ar th

S ci en ce

C o n su lt an ts

S o il an d C o n st ru ct io n M at er ia ls

T es ti n g L ab o ra to ry

Geotechnical Investigation Report for Proposed Joint Force Headquarters

November 9, 2011

Prepared by:

11/09/11

Marcus García Vincenty, M.E.C.E.,P.E., Lic. #15928 Date Geotechnical Engineer

This report consists of 68 Pages

JFHQ Fort Buchanan Guaynabo, Puerto Rico November 9, 2011

Table of Content iii

1. INTRODUCTION

2. scope of work

3. SITE AND PROJECT DESCRIPTION

3.1 Site Description

3.2 Project Description

3.3 Geologic Setting

4. FIELD EXPLORATION

5. LABORATORY TESTING

6. SUBSURFACE CONDITIONS

6.1 Borehole Results

6.2 Laboratory Results

6.3 Groundwater Conditions

7. GEOTECHNICAL CONCLUSIONS AND RECOMMENDATIONS

7.1 2009 IBC Code

7.2 Seismic Liquefaction

7.3 Foundation Recommendations

7.3.1 Discussion

7.3.2 Recommendations to Reduce Shrink/Swell Soils Effects

7.3.3 Slab Mat Foundation

7.4 Subgrade Modulus and CBR Values

7.5 Earthwork Recommendations

7.5.1 Clearing Operations

7.5.2 Cut Procedures

7.5.3 Proof Rolling

7.5.4 Fill Requirements

7.5.5 Uniform Fill Thickness Criteria

7.5.6 Protection of Fill During Construction

7.5.7 Runoff Waters

7.5.8 Erosion Control

8. GENERAL CONDITIONS

8.1 Post-Investigation Services

8.2 Uncertainties and Limitations

9. REFERENCES

9.1 Standards, Codes, and Procedures Cited

Appendix A - Figures

1. Site Location Map

2. Geologic Map

3. Boring Location Plan

4. Uniform Fill Thickness Criteria

Table of Content iv

Appendix B - Boring Logs

Appendix C - Classification Tests

Appendix D - Design Spectrum Data

Appendix E - Declaration

Geotechnical Investigation Report for Proposed Joint Force Headquarters

1. INTRODUCTION

A new structure has been proposed in the Municipality of Guaynabo, Puerto Rico. This report summarizes current geotechnical data concerning the proposed project, based on the information submitted to this office by David Everett, A.I.A. from Jacobs Engineering Group, Inc.. The scope of work of this exploration follows instructions from Arch. Everett as per our approved proposal No. 1257 and signed contract between the two parts.

2. SCOPE OF WORK

The main purpose of the investigation was to analyze the existing subsoil conditions to provide with the geotechnical parameters required for design and construction of the project. Among them, this report gathered the findings and recommendations regarding the following topics:

a. Description of subsurface conditions, boring logs and boring location plan.

b. Groundwater conditions.

c. Seismic considerations per International Building Code (IBC), 2009 edition, and

Seismic Hazard Analysis, including liquefaction potential.

d. Identification of any potentially expansive soils and guidelines.

e. Recommended foundation system, allowable soil bearing capacity and foundation settlement estimates.

f. Modulus of subgrade reaction for use in designing slabs on grade and CBR values for use in pavement design after subgrade preparation.

g. Fill, backfill and compaction recommendations including whether on-site excavated soils are suitable for use as structural fill.

h. Site preparation recommendations for building slab on grade and roadway pavement subgrades.

To fulfill the above tasks, a series of field and laboratory tests were completed. The field activities began with site visits to visually inspect the project area and check accessibility of the drilling equipment. With this, eight (8) Standard Penetration Tests (SPT) boreholes were requested by designer and completed. In addition to routine laboratory tests, which include visual and manual description of samples, moisture content and unconfined compressive strength, Classification Tests and Potential Volume Change Tests were executed on chosen samples.

3. SITE AND PROJECT DESCRIPTION

3.1 Site Description

The site is located in the U.S. ARMY Fort Buchanan within the north coast of Puerto Rico in the

Municipality of Guaynabo, P.R.. An approximate location for the site was obtained by means of reference orientation. The Site Location Map taken from a portion of the USGS 7.5 Minutes

Bayamón Topographic Quadrangle is included as Figure 1 in Appendix A of this report.

According to the aforementioned Topographic Quadrangle, the site elevation should be close to

10 meters above mean sea level. The site topography is gently sloped toward the east.

3.2 Project Description

The proposed project consists in the construction of a Puerto Rico ARMY National Guard Joint

Force Headquarters. The new facility may be 1 or 2-stories, and shall include: administration office spaces, equipment storage, arms vault, locker rooms, training work spaces, IT/media rooms, mail rooms, toilets / showers, and a maintenance training area, and controlled waste areas. Additional components of the project include demolition, site preparation, storm water detention and drainage systems, landscaping, fencing, sidewalks, loading dock, curbs, rigid pavement for military vehicles, flexible paving for POV parking, exterior lighting, utilities, a detached facility sign, and A/T force protection measures. Approximate building gross square footage (total 74,129 ft2).

Column loads estimates were provided to us. These are as follows.

• Wall load: Dead 4000 plf

Live 1000 plf

• Column load: Dead maximum 60 kips

Live maximum 15 kips

Dead minimum 2 kips

Live minimum 0 kips

Plans showing existing and/or proposed elevations have not been provided to us to the preparation of this report. According to site conditions, we have preformed analyses and provide recommendations by considering that no significant fill or cut operations (exceeding three feet in thickness) are expected to be performed to change site elevation. Otherwise recommendations herewith discussed shall be verified and/or amended.

The designer and owner are alerted that if any of the considerations herewith mentioned are not in accordance with project true conditions we shall be alerted in order to verify submitted recommendations. In addition, we also shall be alerted in case the designer notes conditions and/or aspects of the project that were overlooked in this report.

3.3 Geologic Setting

The site has been mapped as part of the Bayamón Geologic Quadrangle, prepared for the U.S.

Geological Survey by Watson H. Monroe (1973). According to this map, Holocene-aged

Alluvium (Qa) are encountered at the project site. Monroe describes this formation as follows:

Qa- Alluvium, “sand, clay and sandy clay; beds of sand containing gravel and cobbles in valleys of Río de Bayamón and Río de la Plata; mostly sandy clay in other valleys. The seaward parts of the valleys of the Río de Bayamón and the Río de la Plata are apparently deltas of the two rivers which built out into a lagoon now filled in by alluvium to form the large swamps in the northern part of the quadrangle. Thickness variable; as much as 25 meters has been penetrated in some wells.”

Figure 2 shows a portion of the mentioned Geologic Map with the described and nearby formations and their respective limits delineated on it.

4. FIELD EXPLORATION

Eight (8) geotechnical test borings were drilled as part of this investigation from August 24 to

August 30, 2011. Seven boreholes, designated as B-1 to B-5 and P-2 and P-3, were executed at locations under proposed structure and were drilled to a maximum depths varying from twenty-five (25) to thirty-five (35) feet. One borehole designated as P-1, twenty-five (25) feet deep, was located within driveway and parking area. All boreholes were stopped at competent subsoil conditions. Figure 3, included in Appendix A, shows the location of boreholes on a site plan provided to us by Jacobs Engineering Group, Inc.. Additional details about the drilling and sampling operations are presented in Appendix B. Details on the subsurface conditions are further discussed in Section 6 of this report.

The test holes were performed using a CME-55 Model Trailer Mounted Drilling Rig. The hammer, used during the Standard Penetration Test (SPT), was a 140-lb. automatic hammer.

The SPT, as described in ASTM D 1586, was used to determine the “NSPT” value and disturbed soil sampling for visual-manual descriptions in accordance with ASTM D 2488. A standard configuration consisting of a 1.375” ID split spoon sampler is used as testing probe and for sample recuperation in this sampling method. The sampler attached at the end of a solid string of drill rods is advanced for an 18-in. or 24-in. interval, depending on the sampler length, using a

140-lb hammer dropped through a 30-in. free fall. The sampler used during this investigation was 24-in length. The blows required to advance the hole for each 6-in. are recorded in a field-boring log. The standard penetration resistance, or “NSPT” value, is the sum of the blows required for the second and third 6-in. drives. The hole is then cleaned to the top of the next interval to be sampled and the procedure is repeated.

The samples and field logs, were collected, secured and transported to our laboratory for routine testing. Samples are secured and transported according to the practice described in ASTM D

4220. Routine testing includes natural moisture content, and unconfined compressive strength on cohesive samples.

5. LABORATORY TESTING

Laboratory testing of soil samples from the borings was performed in our affiliate laboratory which is accredited by AASHTO and certified by the U.S. Corps of Engineers. This testing consisted in visual and manual description of samples, measurement of natural water content determination, unconfined compressive strength, determination of Atterberg Limits and the execution of mechanical grain size analyses. In addition, Potential Volume Change (PVC) tests were executed on selected samples in order to obtain information about possible expansive behavior of soils.

Samples were visually and manually described by following procedures described in ASTM D

2488 Standard Practice for Description and Identification of Soils (Visual-Manual Procedure).

The water content tests were performed in accordance with ASTM D 2216 Standard Test

Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass.

In order to obtain the engineering characteristics of the subsurface soils it was imperative to conduct some classification tests as per ASTM D3282 and D2487. As per criteria of the assigned Geotechnical Engineer, thirteen (13) samples were selected for determination of index properties. Mechanical grain size analyses were performed in accordance with ASTM D 422

Standard Test Method for Particle-Size Analysis of Soils. Atterberg Limits were determined on selected samples according to ASTM D 4318. Refer to Appendix C.

The Potential Volume Change (PVC) test was performed based on the procedures of the Federal

Housig Administration (FHA 701). Samples showing more cohesion were selected for testing since cohesion is directly related to expansive behavior.

All collected field and laboratory data was evaluated in order to provide with the recommendations considered in this report. The reader is referred to the corresponding ASTM’s of each test in order to obtain the description of used procedures.

6. SUBSURFACE CONDITIONS

6.1 Borehole Results

The detected subsoil conditions are in general accordance with the geological reference previously discussed. Relatively homogeneous conditions were detected when comparing each borehole. The detected stratigraphy from the borehole program is composed by three different materials. These are a fill material, cohesive soils (Alluvium) and the underlying limestone up to the maximum explored depth.

The first layer consists of fill material. The thickness of this material varied from six inches to eight feet. There are about 6 inches of topsoil at borings B-1 and B-2. Samples were predominantly found to be composed by gravel, sand, silty clay and clayey silt with sometimes asphalt on the first sample at borings B-4, B-5, P-1, P-2 and P-3. Thickness varies between 2 and 8 feet. N-values for this layer varied from 3 to 20 blows per foot (bpf). Natural water content varied from 6% to 40%. Deleterious material, such as garbage, construction debris, among others, was not detected within the samples. Nevertheless, the presence of this material can not be discarded. It is strongly recommended to perform open test pits during construction in order to check for the presence of deleterious material within the fill and to see if replacement is necessary.

The second layer founded during the drilling consists of medium to high plasticity silty clay with occasional silt pockets. This layer is found from surface in boring B-3 and below the layer of fill and/or top soil at remaining borings up to a depth that varies from 12 to 17 feet. N-values for this layer varied from 2 to 14 bpf. Natural water content varied from 21% to 42%. Uconfined compressive strength was measured on some of the samples. Values ranged from 0.5 to 3.5 tons per square foot (tsf). According to “N” values and measured unconfined compressive strength, the cohesive soils predominantly have a soft to medium stiff consistency.

Atterberg Limits were determined on some of the samples from this layer. Plasticity Index ranged from 22 to 57. This material shows a marginal to very critical expansive behavior a it will be discussed next.

The third layer found during drilling consist of a low to medium plasticity silt and clayey silt and indurated silt, interbedded with Limestone broken by the sampling into coarse to fine gravel and sand. This layer was be found in all the borings drilled and has an N-value that varied from 7 to refusal, or more than a 100 bpf. This layer was found up to a depth that varied from 12 to 17 feet up to the final depth of the borings.

The above given soil characteristics correspond to a general description of the subsoil conditions prevailing at the project site. On account of the generalized form the subsoil profile has been presented above, we encourage the reader to refer to the boring logs for detailed information on the soil characteristics at the borings locations.

6.2 Laboratory Results

Table 1 presents a summary of the tests results used to classify the explored materials.

Table 1 – Summary of Classification Tests

ID Description LL

PL

PI

Gravel

Sand

Fines USCS AASHTO

B-1 Sample 3 fat clay 66 27 39 0.0 14.9 85.1 CH A-7-6(37)

B-2 Sample 1 fat clay 79 33 46 0.0 10.7 89.3 CH A-7-5(48)

B-2 Sample 2 fat clay 68 24 44 0.0 15.4 84.6 CH A-7-6(41)

B-3 Sample 3 fat clay with sand 84 27 57 0.0 26.8 73.2 CH A-7-6(43)

B-4 Sample 3,4 sandy lean clay 47 24 23 0.0 30.4 69.6 CL A-7-6(15)

B-4 Sample 5 fat clay 60 30 30 0.0 5.0 95.0 CH A-7-5(34)

B-5 Sample 2 clayey sand 21 13 8 0.3 70.3 31.0 SC A-2-4(0)

B-5 Sample 4 fat clay 89 29 60 0.0 11.4 88.6 CH A-7-6(61)

P-1 Sample 2 sandy fat clay 51 26 25 1.6 35.4 63.0 CH A-7-6(14)

P-2 Sample 5 fat clay 63 31 32 0.0 3.3 96.7 CH A-7-5(38)

P-3 Sample 2 sandy fat clay 59 23 36 0.0 34.6 65.4 CH A-7-6(22)

P-3 Sample 5 sandy lean clay 47 25 22 0.0 46.7 53.3 CL A-7-6(9)

Refer to Appendix C for more detailed results.

According to a criteria established by O’Neill and Poormoayed, 1980, the potential swell of a given soil can be generally assessed from Atterberg limits as given by the following table.

Table 2 - O’Neill and Poormoayed percent swell correlation.

Liquid Limit

Plasticity Index

Potential swell classification

<50

<25

Low

50-60

25-35

Medium

>60

>35

High

Table 3 tabulates the results of the PVC tests.

Table 3 – Potential Volume Change Test Results

Boring

Sample

Dial Reading

Load (lb)

Swell index (psf)

PVC

(value)

PVC

Category

Liquid Limit

Plasticity Index

B-2 2 55 178 4,275 5.4 Critical 68 44

B-3 3 65 210 5,043 6.4 Very

Critical 84 57

P-3 5 24 78 1,873 2.3 Marginal 47 22

As shown in the table, the samples revealed a marginal to very critical potential. The reader should be aware that samples from boreholes B-2 and B-3 better represent the characteristics of most of the subsoil conditions from the cohesive samples obtained below the fill material, when encountered, and over the limestone of the area. Therefore expansive behavior is a predominant characteristic of the bearing subsoil at the site as per visual and manual inspection of samples and based on the results from Atterberg Limits.

6.3 Groundwater Conditions

The groundwater table (GWT) underlying the site was encountered during drilling operations at some of the boreholes. Table 4 shows the approximate depth of groundwater encountered in the boreholes during and after drilling. Depth of groundwater was measured from borehole surface.

The reader should be aware that a confined groundwater condition was detected in borehole B-4 where water was measured at about six (6) feet from surface during drilling and at surface after drilling was completed.

Table 4 – Approximate Groundwater Elevation

Borehole Depth

During Drilling Depth

After Drilling B-1 13’ 13’ B-2 6’ 6’ B-3 13’ 13’ B-4 6’ 0’ B-5 13’ 13’ P-1 Not detected Not detected P-2 6’ 6’ P-3 18’ 18’

However, these levels shall not be considered invariant and accurate. Monitoring wells are necessary in order to provide accurate groundwater levels with time. These were beyond the scope of work of this study. In addition, it should be noted that the groundwater table is always being affected by natural factors such as the distance from water sources, the permeability of the subsoil, the topography of the area, and the amount of precipitation. Moreover, it should be taken into account that whenever changes in the topography of a site are made, changes in the groundwater characteristics of the region frequently occur. Such conditions are difficult to detect within the normal scope of time of the exploration.

7. GEOTECHNICAL CONCLUSIONS AND RECOMMENDATIONS

7.1 2009 IBC Code

According to the International Building Code (IBC) 2009, the soils at the site fall into the Soil

Profile Type SE since Plasticity Index of samples is higher than 10 for a layer with thickness higher than 20 feet. Below you may find the IBC 2009 Design Spectra Graph according to the

Java Ground Motion Parameter Calculator from the U.S.G.S. web page.

Appendix D shows the detailed results from the Spectrum computations.

7.2 Seismic Liquefaction

Liquefaction is the transformation of a cohesionless material from a solid state into a liquefied state as a consequence of increased pore pressure and reduced effective stress.

One of the most dramatic causes of damage to engineering structures during an earthquake has been the development of liquefaction in saturated sand deposits. Seed (1965) has made significant contribution in studying the phenomenon of liquefaction. Based on Seeds studies, if saturated cohesionless soils are subjected to earthquake ground vibrations, the resulting tendency to compact will be accompanied by an increase in porewater pressure in the soil and a resulting movement of water from the voids. Water is thus caused to flow upward to the ground surface, where it emerges in the form of mud spouts or sand boils. The development of high pore water pressure due to ground vibration and the resulting upward flow of water may turn sand into

"quick" or liquefied conditions.

The subsoil conditions disclosed by the test borings program showed that no liquefaction problems should be expected during seismic activity since no saturated sands were encountered in borings locations.

7.3 Foundation Recommendations

7.3.1 Discussion

The following statements summarize the most important findings from field and laboratory tests that lead to the geotechnical recommendations to be discussed in the next sections:

• Soft to medium stiff consistency soils were disclosed by the test boreholes within the upper ten (10) feet from surface. Conventional spread footings will not provide with a satisfactory foundation alternative since settlements will negatively affect the structure aesthetic and functionability.

• Samples bearing proposed loads were found to be expansive.

• Fill material was found to depths of about six and eight feet from surface in boreholes B-

5 and P-2, respectively. This condition is recommended to be attended during construction by means of open test pits and proof rolling. Refer to Section 7.5.1.

• Confined groundwater conditions were detected in borehole B-4. This condition, which may be present at other areas of the site, shall be considered when designing proposed elevations. Excavations below groundwater table shall be avoided since expansive behavior of insitu soils will be activated in addition to the typical problems that dewatering procedures represent.

Based on the mentioned conditions, we strongly recommend designing the proposed structure over slab mat foundation to be cast over a soil buffer with minimum thickness of about two (2) feet. The concept of a slab mat foundation is known as a slab-on-ground thickened at portions where columns loads are to be distributed.

It is of outmost importance that these guidelines and recommendations are strictly followed in order to reduce the occurrence of differential settlements and to design and construct a foundation system capable to tolerate their occurrence.

7.3.2 Recommendations to Reduce Shrink/Swell Soils Effects

In order to reduce shrink-swell problems during and after the construction of the proposed structures, the following measures shall be adopted:

• Avoid cut operations. This will activate the changes in moisture content of the subsoil, thus producing volume changes. Where excavations are to be performed, all exposed surfaces in the excavations shall be covered with polyethylene. This will reduce the gain and/or loss of moisture of the in-situ soil that could cause volumetric changes. Do not use “permeable” soils for fills under or around structures.

• Do not use jointed pipe (e.g. cast iron) for sewage lines. Pipes often “sweat” and progressively break.

• Provide always positive drainage away from the structure.

• Direct flow from gutter downspouts away from the structure via paved drainage ways and with underground collection systems.

• Use splash guard under exterior water spigots and air-conditioning units

(condensate line and pan), to direct water away from structure via paved drainage ways.

• Backfill old trenches, excavations, etc., with non-permeable soil prior to construction at a site. Remove and backfill tree stumps with non-permeable material.

• When backfilling excavations, the backfilling material shall be composed of A-2-6, A-4 to A-6 material compacted to more than 90% of maximum dry density and slightly above moisture content. This procedure will help in reducing run-off water seeping into the subsoil.

• Plant trees at a distance of about 1.5 times the mature height of tree.

• Use “slip” joints for interior partitions.

7.3.3 Slab Mat Foundation

In view of the results from the subsoil exploration, it is considered that subsoil conditions are capable of resisting the proposed loads always that recommendations herewith included are strictly followed.

It is strongly recommended that the mat foundation rest over a buffer having a minimum thickness of about two (2) feet. This buffer shall extend at least one (1) meter beyond the structure perimeter. The soil buffer shall consist of engineering fill with characteristics and placed as described in Section 7.5.4 Fill Requirements of this report. In addition, a uniform fill thickness criteria shall be followed as discussed in Section 7.5.5.

For a mat foundation, the structural design can be carried out by two conventional methods: the conventional rigid method and the approximate flexible method. In the conventional rigid method of design, the mat is assumed to be infinitely rigid. Also, the soil pressure is distributed in a straight line, and the centroid of the soil pressure is coincidental with the line of action of the resultant column loads, as shown in the following figure:

The great disadvantage of the rigid method is that mats are not truly rigid, so the settlements beneath the columns will be greater than that beneath unloaded areas. These differential settlements will cause variations in the soil bearing pressure and corresponding changes in the flexural stressed in the mat.

In the approximate flexible method of design, the soil is assumed to be equivalent to an infinite number of elastic springs. This is sometimes referred to as the Winkler foundation. The elastic constant of these assumed springs is referred to as the coefficient of subfrade reaction, k. The following figure graphically shows the concept:

Depending on column spacing, the structural mat may be designed as per one of these methods.

Bearing pressures shall not exceed 2,500 psf.

Resultant of Soil Pressure

Q3

Q2 Q1

ΣQ

Q1 Q2

For the approximate flexible design method, the following Modulus of Subgrade Reaction (ks) can be used. According to Joseph E. Bowles in his Foundation Analysis and Design textbook

(Fifth Edition), he has suggested the following for approximating kS from the allowable bearing capacity qa furnished by the geotechnical consultant:

Fps: kS = 12(SF) qa k/ft3

Where qa is equal to 2.5 ksf. This equation is based on qa = qult/SF and the ultimate soil pressure is at a settlement ΔH = 1 inch and kS is qult/ ΔH. Therefore kS for a ΔH varying from 1 inch to 1.5 inches corresponds to values of 52 p.c.i. and 35 p.c.i., respectively. This is for a SF equal to 3.0.

The structure is recommended to be designed for a maximum settlement of about 1.5 inches.

The value of (k1) above given is based on our experience on the type of soil expected at the project site. For a more accurate value, field plate bearing tests would have to be made. But, for all practical purposed the estimated value can be safely used.

Because it is difficult to develop accurate ks values, it may be appropriate to conduct parametric studies to evaluate its effect on the mat design. American Concrete Institute suggests varying ks from one half the computed value to 5 or 10 times the computed value.

The modulus of subgrade reaction (ks) needs to be larger near the edges of the mat and smaller near the center. It is recommended to double the ks values along the perimeter of the mat.

7.4 Subgrade Modulus and CBR Values

Once the recommendations discussed in the Earthwork Recommendations of the report to be submitted are completed under the satisfaction of the Geotechnical Engineer supervising the earthworks, the construction of the pavement may begin.

For the construction and design of a flexible or rigid pavement the following soil material with their respective strength parameters can be used.

Base - An untreated aggregate soil classifying A-1-a (AASHTO) is recommended as base material. A CBR value of 35 or a “k” value of 350 pci can be assigned to this type of soil for designing flexible or rigid pavements, respectively.

Subbase - An untreated aggregate material classifying A-2-4 (AASHTO) is recommended as subbase course. A CBR value of 20 or a “k” value of 250 pci can be used.

Subgrade - After proof rolling operations, a CBR value of 3 or a "k" value of 90 pci can be assigned to the in-situ soils.

7.5 Earthwork Recommendations

The earthwork operations constitute a very important aspect of the geotechnical design in any project. Therefore, it is strongly recommended that our services, or the services of a qualified

Geotechnical Engineer, are retained in order to observe earthwork operations in a full time basis starting with the cleaning operations. Sufficient notification to the Geotechnical Engineer or firm prior to commencement of earthwork operations is essential.

7.5.1 Clearing Operations

The first step to be followed corresponds to the clearing and grubbing operations. The clearing operations shall be performed thoroughly and consciously. Minimum thickness of material to be removed shall be of about 12 inches. The existence of deleterious material, such as garbage, organics, construction debris, among other, within additional areas which removal is mandatory can not be discarded. Existing foundations, underground utilities, septic tanks, among other structures, shall be completely removed prior to beginning of construction. The final depth and aerial extent for material removal will be established by the Geotechnical

Engineer or his representative.

Open test pits at locations selected by the Geotechnical Engineer of the project shall be performed at those areas close to boreholes B-5 and P-2 in order to verify the composition of the fill material encountered. The presence of deleterious and/or compressible materials such as garbage, organics, construction debris, among others, will make obligatory its replacement by engineering fill as discussed in this report.

7.5.2 Cut Procedures

The designer shall have in mind, as previously recommended, that proposed elevations shall be designed in order that cut operations are reduced as much as possible since subsoil conditions were found to be expansive.

The site grading shall be so that runoff is disposed of out of the excavation and embankment areas.

The rippability of the terrain suggests that track-type/heavy earth movement equipment like tractors, loaders, excavators, and assisted scrappers could initially perform the stripping and cut related task.

7.5.3 Proof Rolling

Only after completion of the clearing works further works shall be allowed. Once the deleterious materials are removed to the satisfaction of the observing soils engineer (in a full time basis) and the necessary cut operations performed, the exposed surface shall be proof rolled using a 20-ton non-vibratory roller. Any soft spot disclosed during the proof rolling operations shall be removed and replaced with select engineered fills, as recommended in Section 7.5.4. The roller shall be applied over any given area at least 10 times, or 5 round trips, at a velocity not exceeding 1.5 miles per hour.

7.5.4 Fill Requirements

The engineering fill and/or backfill used to attain the final grade below structures shall resemble the characteristic of an A-2-6, A-4 to A-6 (based on the AASHTO Soil

Classification System). Samples of all potential sources of fill material must be submitted to the soils laboratory to establish their acceptance. It is considered that material to be cut from the project to reach final elevation may be used as engineering fill. Nevertheless, proper classification tests shall be performed during cut operations to verify its characteristics.

Every layer shall be compacted so that the dry unit weight of the material is equal to or greater than 95 percent of its maximum dry unit weight as obtained in the laboratory under a Modified Proctor Compaction Test (ASTM D-1557). The moisture content of the fill material, prior to compaction, shall be varying from minus 2% to plus 3% of optimum, as determined by the Modified Proctor Test. The water content of the fill may be reduced when necessary by any appropriate procedure. The water content may be increased by addition of water on the fill or in the borrow area. In either case, the addition of water must be made by the contractor and distributed evenly through the material prior to compaction. It should be the responsibility of the Resident Engineer to instruct the Soils Engineer retained by the owner on a consultative basis to determine the optimum moisture and corresponding dry density of the fill to be used in this project.

Over the engineering fill material the contractor should employ a 20-ton vibratory steel roller, or heavier, to obtain the required percentage of compaction. Care shall be adopted while working close to the existing structures since roller vibrations might provoke hair line cracks. One solutions is to reduce fill loose thickness and to compaction without vibration. Another solution is to monitor structures with seismograph in order to measure accelerations and to determine a safe buffer distance between structures and rollers. The contractor shall not place any additional fill until the preceding compacted layer has been found to fulfill the aforementioned compaction criteria. The contractor shall employ suitable equipment, to obtain the required compaction. The number of passes of the equipment over each section of the work surface shall be determined in the field. However, the soils engineer shall determine the density of the fill material after the compaction of each twelve (12) inches layer, and the contractor shall not place any additional fill until the preceding compacted layer has been found to fulfill the aforementioned requirements. Each successive pass shall overlap the preceding adjacent pass by

10 percent. Roller passes made on material in unsuitable condition will not be considered in judging compliance with these specifications. Should the contractor fail to obtain the required compacting energy, he must get the appropriate equipment to comply with the compacting criteria.

Filling shall be conducted so that no obstruction to drainage from other sections of the fill areas is created. Sumps, if any, shall be maintained in effective operating condition for the duration of the works.

Each layer of fill shall be inspected prior to compaction. All visible roots, vegetation or debris shall be removed. Stones larger than 6 inches in diameter for fine soil fills shall be removed or broken. Material incorporated in the fill which is not satisfactory shall be subjected to rejection and removal at the Contractor's expense.

The acceptability of the compacted fill will be established by tests (state whether at Contractor's or Owner's expense). The unit weight of compacted material will be established by in-place density tests conducted by the Soil Consultant (at the Resident Engineer's request) by the sand-cone, balloon or nuclear testing procedures, all in accordance to ASTM requirements.

Additional tests to establish or confirm maximum density, optimum moisture content, and percentage stone content will be performed as required during the progress of the works.

The fill procedures shall be performed at the early stages of construction. This will allow some time for the stabilization of the subsoil and the materials that conform the embankment.

Intermediate and final grade elevations and slopes shall provide all earthworks of correct ways of drainage. The accumulation of water over the area diminishes the effect of the soil compaction effort.

All permanent fill slopes shall maintain a maximum 2 Horizontal: 1 Vertical steepness at all times. Again proper drainage ways shall be established in these slopes to avoid runoff water across their faces. These measures shall include gutters, drainage pipes, and spillways. Also, it is recommended the seeding of grass, or any other dense vegetation to assist in controlling erosion along the slope face. Please consult a landscape professional for further recommendations.

Project designers shall observe building setbacks established in the applicable building codes when having structures adjacent to cut or fill slopes.

7.5.5 Uniform Fill Thickness Criteria

No structure, and this include ground floor slabs, shall be allowed to rest simultaneously over a surface which has been partially cut and partially filled. Additionally, the difference in fill thickness under any given structure, including ground floor slabs, shall not exceed two (2) feet. Areas presenting such grading conditions will need to be deepened in order to reduce the difference in fill thickness to a maximum of 2 feet. An over-cut to equalize fill thickness is mandatory. This procedure is graphically explained in Figure 4.

7.5.6 Protection of Fill During Construction

Layer placement and thickness shall be controlled so that no pounding of water can occur on any working surface. This shall be accomplished without at any time exceeding the specified maximum layer thickness. In addition to performing the grading operations necessary to insure unobstructed run-off at all times from every point on the working surface, the contractor shall be required to seal the working surface at the close of each day's operation and when practical, prior to rainfall. Sealing shall be accomplished by rolling the surface with a smooth wheel roller of approved design and weight. No fill shall be placed until an approved roller of this type is delivered to the job and demonstrated to be in working condition.

7.5.7 Runoff Waters

Run-off waters shall not be permitted to drain off the face of the exposed fill and cut slopes. To prevent the run-off from spilling over the face of the slopes, longitudinal concrete drainage swales shall be provided at the slope benches. The drainage swales will be provided with proper gradients so as to properly dispose the surface run-off through the swales and into properly designed outlets.

It is strongly recommended that grading of lots is designed and constructed in order to direct run-off away from slopes.

Where no benches are required for the slopes, the construction of the concrete swale immediately adjacent to the top of the cut and one at the cut toe shall be performed.

Regarding the exposed slope faces several additional measures shall be evaluated in order to further minimize erosion. This is discussed in detail next.

7.5.8 Erosion Control

Rain, surface water, and even the same dwellers walking over the embankment and cut slopes promote particle migration from the soil mass. Erosion, in an advanced stage, can lead to stability problems such as local slope and foundation failures. There are some feasible and cost-effective protection devices that can be considered in order to minimize the erosive action produced by these conditions.

Along these lines, the face of all the slopes shall be protected providing, for example, erosion control blankets, three-dimensional Geocells, or promoting the growth of highly erosion-resistant vegetation, such as robust rooted grasses.

The blankets consist of an open-mesh-type fabric in conjunction with straw, mulch, wood pieces, or coconut fiber. These blankets are very useful in controlling soil erosion because they reduce the runoff velocity while enhancing seed germination and vegetative growth above the soils being protected.

Regardless which protection is finally selected for this project, is at most to apply it as soon as the cut and fill slopes are finished. However, at areas where high and/or constant flow conditions will prevail, stronger remedial actions will need to be considered. Accordingly, provisions for aprons and cutoffs (embedded end sections) should constitute normal design provisions for preventing undermining in this area.

8. GENERAL CONDITIONS

8.1 Post-Investigation Services

During final design and during construction it may be necessary to modify recommendations made in this report to account for new information or the occurrence of situations that were not considered in preparing these recommendations. For that reason, geotechnical design cannot be considered complete until construction is complete, and the Geotechnical Engineer providing future services must necessarily review all geological and geotechnical data, conclusions, and recommendations and either confirm the conclusions and recommendations or recommend changes to them. Future geotechnical services are an important and necessary continuation of this investigation.

Foundation and grading plans as well as specifications related to construction should be reviewed by a qualified Geotechnical Engineer to verify that the intent of the recommendations presented in this report has been properly interpreted and incorporated into the contract documents.

A qualified Geotechnical Engineer should perform Geotechnical observation and testing during excavation, foundation construction, and related earthwork operations. The purposes of the geotechnical observation and testing are to correlate the findings of this and future investigations with actual subsurface conditions exposed during construction, and to provide revised or supplemental recommendations, if necessary. The geotechnical observation and testing will also confirm that foundations are founded in the recommended soils, and that suitable fill and backfill soils are placed upon competent materials and properly compacted to meet the project specifications.

8.2 Uncertainties and Limitations

Only a very small portion of the subsurface conditions at the site had been observed and/or tested. The possibility of subsurface conditions differing from those assumed and developed in this investigation cannot be discounted. Conclusions and recommendations presented in this report are based upon our understanding of the subsoil conditions depicted by the borings drilled and the assumption that the subsurface conditions do not deviate appreciably from those disclosed by the field exploration.

Professional judgments presented in this report are based on an evaluation of the technical information gathered and our general experience in the field of Geotechnical Engineering. We do not guarantee the performance of the project in any respect, only that the engineering work and judgment rendered meet the standard of care of the geotechnical profession at this time.

9. REFERENCES

Department of the Navy, 1986. Soil Mechanics – NAVFAC Design Manual 7.01

Duncan, J. Michael and Wright, Stephen G., 2005. Soil Strength and Slope Stability, John Wiley

& Sons, New Jersey.

Freeman, T.J., Littlejohn, G.S., and Driscoll, R.M.C., 1994 Has your house got cracks?:

Institution of Civil Engineers and Building Research Establishment, London, Great Britain

Kulhawy, F.H., Mayne, P.W., 1990. Manual on Estimating Soil Properties for Foundation

Design, Electric Power Research Institute, California, U.S.

Peck, Ralph B., Hanson, Walter E. and Thornburn, Thomas H., 1974. Foundation Engineering, 2nd ed. John Wiley & Sons, New York.

USGS, 1969 Bayamón Quadrangle, Puerto Rico 7.5-Minute Series (Topographic). (Photorevised

1982): U.S. Geological Survey.

Watson H. Monroe, 1973 Geologic Map of the Bayamón Quadrangle: U.S. Geol. Survey Map I-

Wray, Warren K., edited by, 1995, So your home is built on expansive soils: American Society of

Civil Engineers, Virginia, U.S.

9.1 Standards, Codes, and Procedures Cited

ASTM D 422 "Standard Test Method for Particle-Size Analysis of Soils." Annual Book of ASTM

Standards - Volume 04.08 - Soil and Rock (I): D420 to D5779.

ASTM D 1557 "Standard Test Methods for Laboratory Compaction Characteristics of Soil Using

Modified Effort (56,000 ft-lbf/ft3)" Annual Book of ASTM Standards - Volume 04.08 - Soil and Rock (I): D420 to D5779.

ASTM D 1586 "Standard Test Method for Penetration Test and Split-Barrel Sampling of Soils."

Annual Book of ASTM Standards - Volume 04.08 - Soil and Rock (I): D420 to D5779.

ASTM D 2216 "Standard Test Method for Laboratory Determination of Water (Moisture)

Content of Soil and Rock by Mass." Annual Book of ASTM Standards. Volume 04.08 - Soil and Rock (I): D420 to D5779.

ASTM D 2487 "Standard Practice for Classification of Soils for Engineering Purposes (Unified

Soil Classification System)." Annual Book of ASTM Standards - Volume 04.08 - Soil and

Rock (I):D420 to D5779.

ASTM D 2488 "Standard Practice for Description and Identification of Soils (Visual-Manual

Procedure)." Annual Book of ASTM Standards - Volume 04.08 - Soil and Rock (I): D420 to

D5779.

ASTM D 3282 "Standard Practice for Classification of Soils and Soil-Aggregate Mixtures for

Highway Construction Purposes." Annual Book of ASTM Standards - Volume 04.08 - Soil and Rock (I):D420 to D5779.

ASTM D 4220 "Standard Practices for Preserving and Transporting Soil Samples." Annual Book of ASTM Standards - Volume 04.08 - Soil and Rock (I):D420 to D5779.

International Building Code (2009). International code Council – Fifth Printing

APPENDIX A

FIGURES

Geotechnical Report of Subsoil Exploration For Proposed JFHQ at

Fort Buchanan, Guaynabo, PR Fig. 1 USGS Site Map from USGS

Bayamón, Quadrangle

MGV GEOTECHNICAL GROUP, PSC.

PO BOX 19480

SAN JUAN, PR 00910

1:20,000 Project No.: 1095

SITE

Geotechnical Report of Subsoil Exploration For Proposed JFHQ at

Fort Buchanan, Guaynabo, PR Fig. 2 USGS Preliminary Report on the Geology of the Bayamón Quadrangle, Puerto Rico

MGV GEOTECHNICAL GROUP, PSC.

PO BOX 19480

1:20,000 Project No.: 1095

SITE

Geotechnical Report of Subsoil Exploration For Proposed

JFHQ at Fort Buchanan, Guaynabo, PR Fig. 3 Approximate Boring Location

MGV GEOTECHNICAL GROUP, PSC.

PO BOX 19480

NTS Project No.: 1095

Prepared by: L.A.

Approved by: MGV

Geotechnical Investigation Report For Proposed JFHQ at Fort Buchanan, Guaynabo, P.R.

Fig. 4 Uniform Fill Thickness Criteria

MGV GEOTECHNICAL GROUP, PSC.

PO BOX 19480

Not true scale Project No.: 1095

OF 2-FT

APPENDIX B

BORING LOGS

0.0

-0.6

-1.2

-1.8

-2.4

-4.0

-5.5

-7.0

-8.5

50/4"

Fill (6" thick), then Silty CLAY, trace coarse to fine sand, trace angular gravel, red, weak red, black pockets, Lignite As above, stiff

As above, medium stiff, without Lignite (?), light gray pockets

As above

As above, stiff

Clayey SILT, trace fine sand, medium plasticity, yellowish red, pale brown

Silty CLAY, trace fine sand, high plasticity, yellowish red, reddish brown

Clayey SILT, little coarse to fine sand, medium plasticity, pale brown

Silty CLAY, some coarse to fine subangular gravel, medium plasticity, pale brown

(limestone)

26.7

28.8

29.6

33.3

29.5

28.7

46.6

17.7

17.6

27 66 39

2.5A

3.0A

3.0A

3.5A

4.0A

BORING NO. B-1

SHEET 1 OF MGV Geotechnical Group, PSC JOB NO. 1095

PROJECT JFHQ Fort Buchanan DATE STARTED 8/26/11 LOCATION Guaynabo, PR COMPLETED 8/26/11

SAMPLER: DRILL MACHINE CME55

TYPE Split Spoon SIZE 1.375" ID DRILLER L. Santiago HAMMER: WT 140 lbs DROP 30 in GROUND ELEV.

DESCRIPTION: la APPROVED: mgv DEPTH OF HOLE 35 FINAL WATER DEPTH: 13' ft. INITIAL WATER DEPTH: 13' ft. WATER TABLE 13'

U.S.C.S. - UNIFIED SOIL CLASSIFICATION SYSTEM DESIGNATION. UNLESS OTHERWISE SPECIFIED, ARBITRARY COORDINATES USED.

NF, WATER TABLE NOT FOUND. *qu - UNCONFINED COMPRESSION STRENGTH; REPORTED VALUES

WN,WP,WL AND IP - NATURAL WATER CONTENT, PLASTIC LIMIT, OBTAINED FROM:

LIQUID LIMIT AND PLASTICITY INDEX (IP A. POCKET PENETROMETER

WL - WP) RESPECTIVELY. B. SPRING TEST

D E

P T

H ft

E L

E V

(m

S A

M P

L E

N O

B lo w s p er in in cr

S P

T N

V A

L U

E (B

L O

W S

/F T

S A

M P

L E

R

MATERIAL DESCRIPTION

S Y

M B

O L

R

E C

O V

E R

Y

Wn

MOISTURE CONTENT

Wp Wl Ip qu*

STRENGTH

(TSF)

PROPERTIES VS. DEPTH

10 20 30 40 50 60 70 80 90 N value Wn

PL

LL

-10.1

-10.7

10 50/4" >100 As above, some coarse to fine sand

END OF BORING

13 13.6 1.5A

BORING NO. B-1

SHEET 2 OF MGV Geotechnical Group, PSC LOCATION Guaynabo, CODE NO. 1095

D E

P T

H ft

E L

E V

(m

S A

M P

L E

N O

B lo w s p er in in cr

S P

T N

V A

L U

E (B

L O

W S

/F T

S A

M P

L E

R

MATERIAL DESCRIPTION

S Y

M B

O L

R

E C

O V

E R

Y

Wn

MOISTURE CONTENT

Wp Wl Ip qu*

STRENGTH

(TSF)

PROPERTIES VS. DEPTH

10 20 30 40 50 60 70 80 90 N value Wn

PL

0.0

-0.6

-1.2

-1.8

-2.4

-4.0

-5.5

-7.0

-8.5

WH

50/6"

50/6"

>100

>100

Fill (6" thick), then Medium stiff Silty CLAY, trace fine sand, high plasticity, light gray, black mottled, trace roots As above, light gray, trace roots

As above

As above, light gray, reddish brown mottled

As above, light gray, rellowish brown, black mottled, medium stiff to stiff

Silty CLAY, trace coarse to fine sand, medium plasticity, yellowish brown, brown, black pockets

Clayey SILT, trace fine sand, medium plasticity, brown, reddish brown, white mottled

Coarse to fine Sandy coarse to fine angular GRAVEL, little silt, pale brown (limestone)

Coarse to fine Sandy Silty CLAY, trace coarse to fine subangular gravel, pale brown (limestone)

41.1

43.4

46.5

43.7

39.8

27.9

23.0

11.6

24.5

1.0A

3.5A

1.0A

1.0A

3.0A

1.0A

1.0A

0.5A

BORING NO. B-2

SHEET 1 OF MGV Geotechnical Group, PSC JOB NO. 1095

PROJECT JFHQ Fort Buchanan DATE STARTED 8/26/11 LOCATION Guaynabo, PR COMPLETED 8/26/11

SAMPLER: DRILL MACHINE CME55

TYPE Split Spoon SIZE 1.375" ID DRILLER L. Santiago HAMMER: WT 140 lbs DROP 30 in GROUND ELEV.

DESCRIPTION: la APPROVED: mgv DEPTH OF HOLE 35 FINAL WATER DEPTH: 6' ft. INITIAL WATER DEPTH: 6' ft. WATER TABLE 6'

U.S.C.S. - UNIFIED SOIL CLASSIFICATION SYSTEM DESIGNATION. UNLESS OTHERWISE SPECIFIED, ARBITRARY COORDINATES USED.

NF, WATER TABLE NOT FOUND. *qu - UNCONFINED COMPRESSION STRENGTH; REPORTED VALUES

WN,WP,WL AND IP - NATURAL WATER CONTENT, PLASTIC LIMIT, OBTAINED FROM:

LIQUID LIMIT AND PLASTICITY INDEX (IP A. POCKET PENETROMETER

WL - WP) RESPECTIVELY. B. SPRING TEST

D E

P T

H ft

E L

E V

(m

S A

M P

L E

N O

B lo w s p er in in cr

S P

T N

V A

L U

E (B

L O

W S

/F T

S A

M P

L E

R

MATERIAL DESCRIPTION

S Y

M B

O L

R

E C

O V

E R

Y

Wn

MOISTURE CONTENT

Wp Wl Ip qu*

STRENGTH

(TSF)

PROPERTIES VS. DEPTH

10 20 30 40 50 60 70 80 90 N value Wn

PL

-10.1

-10.7

10 16 50/6"

>100 As above

END OF BORING

33 24.5 1.0A

BORING NO. B-2

SHEET 2 OF MGV Geotechnical Group, PSC LOCATION Guaynabo, CODE NO. 1095

D E

P T

H ft

E L

E V

(m

S A

M P

L E

N O

B lo w s p er in in cr

S P

T N

V A

L U

E (B

L O

W S

/F T

S A

M P

L E

R

MATERIAL DESCRIPTION

S Y

M B

O L

R

E C

O V

E R

Y

Wn

MOISTURE CONTENT

Wp Wl Ip qu*

STRENGTH

(TSF)

PROPERTIES VS. DEPTH

10 20 30 40 50 60 70 80 90 N value Wn

PL

0.0

-0.6

-1.2

-1.8

-2.4

-4.0

-5.5

-7.0

-7.6

50/6"

50/4"

>100

>100

Medium stiff, Silty CLAY, trace fine sand, medium plasticity, yellowish brown, reddish brown Stiff, Silty CLAY, trace fine sand, little silt in pockets, high plasticity, light gray, red, reddish brown, trace roots

As above, medium stiff, trace silt in pockets

As above, little silt in pockets

As above

Clayey SILT, trace fine sand, medium plasticity, reddish brown, light gray

As above, little coarse to…