36C24818R0193-00003003.pdf

REPORT FOR

UTILITY EXPLORATION

AT

VA248P-0888 VA REPLACEMENT OF PERIMETER

FENCE BORING SITES

PROJECT

SUBSURFACE UTILITY EXPLORATION

enery.dorta Typewritten Text enery.dorta Typewritten Text enery.dorta Typewritten Text enery.dorta Typewritten Text enery.dorta Typewritten Text enery.dorta Typewritten Text

Subsurface Designating Technologies Corp.

PO Box 41062 San Juan. PR 00940 ogarcia@sdtechpr.com

787-586-9629

September 9, 2014

Enery Dorta, RA Gautier & De Torres 1403 Calle Georgetti San Juan, PR 00910

RE: VA248P-0888 VA Replacement of Perimeter Fence Boring Sites Subsurface Utility Engineering Study

San Juan, Puerto Rico

Dear Ms. Dorta:

SD Tech Corp. is pleased to submit this findings report on the Subsurface Utility Exploration services (SUE) performed for the above referenced project.

SD TECH has executed this study following the recommendations of the American Society of Civil Engineers (ASCE) - “Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data – CI/ASCE 38-02”. This guideline defines the quality of utility location and the attribute information that is placed on plans.

In some cases, current technology may not be capable of finding information about certain utilities.

SD TECH has followed best practices within the Subsurface Utility Exploration industry current standard of care in order to provide the best possible information within the proposed Quality Level.

We appreciate the opportunity of being part of your team on this project.

SD TECH will be available to answer any questions upon request.

Sincerely, SD Tech Corp.

Orlando Garcia President/Owner mailto:ogarcia@sdtechpr.com

Findings Report

VAH Fence ProjectVAH Fence project report

Subsurface Utility Exploration

VA248P-0888 VA Replacement of Perimeter Fence Boring Sites

Site

SD Tech scanned at the sites for 16 proposed area boring at the “Veterans affairs Hospital San Juan, PR. The studied area at each site is approximately 20 feet in radius. SD Tech scanned the area for indications of utilities or structural components.

Equipment

Field Conditions

The site was grass and gravel. The weather was mostly cloudy while performing the study.

Limitations

The success for the location of non-exposed, and in this case unknown, underground features depends on the ability to induce a traceable electromagnetic signal on the feature; or being able to transmit and receive an interpretable radar signal.

Induced fields must travel through existing fill or structures in order to be received.

Site conditions were generally appropriate for designating utilities in this project

Findings

By means of the above mentioned methods, SD TECH designated the location of all areas for possible conflicting utility were boring was to be performed.

No utilities was found that would have been in close contact with proposed areas of boring.

SD TECH utilized two different types of equipment in search of utilities in this project: Ridgid SR-60 Seek Tech Receiver and a Malå Geoscience Easy Locator GPR with a 350MHz shielded antenna. This equipment covers a wide range of the electromagnetic spectrum, including the following frequencies: 400Hz, 512Hz, 560Hz, 815Hz, 1 KHz, 8 KHz, 29 KHz, 80 KHz, 83 KHz, 200 KHz, and 350 MHz.

VAH Fence ProjectVAH Fence project report

We look forward to provide the best possible service to you and your clients within available means, methods and experience. We appreciate the opportunity of being part of your team.

Should you have any questions, please contact us.

Sincerely:

SD TECH Corp.

Orlando Garcia President/owner

Project No. 672-12-606 Replacement of Perimeter Fence Task Order No. VA248-14-J-4529 VACHS, San Juan, PR

A / E P r of es s i ona l S er v ic e s

C ont r ac t N um b er V 248- P-0888

In def in i t e Qu ant i t y

M ul ti d is c i p l i ne f or A / E S er v ic es

V A Car ib bea n Hea l t hc ar e S y s t em P uer t o R ic o

P r ep ar ed by

Ga ut ie r & de Tor r e s 140 3 Geo r get t i S tr e et

S an J u an, P R 009 09- 21 42

APPENDIX B:

GEOTECHNICAL ENGINEERING REPORT

SUBSOIL EXPLORATION AND

GEOTECHNICAL ENGINEERING REPORT FOR

PERIMETER FENCE FOR

VETERANS AFFAIRS CARIBBEAN HEAL THCARE CENTER

RIO PIEDRAS, PUERTO RICO

MSC 343 SAN JUAN, PUERTO RICO 00926-6023 PHONE NO. (787) 648-2224 FAX NO. (787) 755-6643

Geotechnical Engineering Services. PSC

GEOTECHNICAL ENGINEERING REPORT FOR

PERIMETER FENCE FOR

VETERANS AFFAIRS CARIBBEAN HEALTHCARE CENTER

RIO PIEDRAS, PUERTO RICO

Gautier & De Torres, Architects

*DESIGNERS*

Geotechnical Engineering Services, PSC

*GEOTECHNICAL CONSULTANTS*

,\ISC 343. A~ .JLA:\. P.R. 009.:!6-6023

Submitted on August 25, 2014 Job No. 142797

PliO\; F. 0. (787) MS-2224 F~X \:0. C7S7 J 7:'5-6643

TABLE OF CONTENT

1.0 INTRODUCTION

2.0 SITE LOCATION AND PROJECT DESCRIPTION

3.0 WORK PERFORMED

4.0 GENERAL SITE GEOLOGY

5.0 SUBSOIL CONDITIONS

5.1 Perimeter of VA Healthcare Center (Borings 1, 3, 4, 5, 6, 7, 9, and 11)

5.2 Zones of Concern (Borings 2, 8, and 1 0)

6.0 GROUNDWATER

7.0 GENERAL

8.0 DISCUSSION

9.0 ENGINEERING RECOMMENDATIONS

9.1 Shallow Foundations Alternative

9.1.1 Temporary Excavations

9.2 Cast in Place Caissons Alternative

9.2.1 Considerations for Drilled Caisson Utilization

9.2.2 Lateral Resistance ofPiles

10.0 ADDITIONAL COMMENTS

Appendixes

Figures

Boring Logs

MSC 343 SAN JUAN. PUERTO RICO 009:!6-6023 PHONE NO. (787) 648-2224 FAX NO. (787) 755-6643

Geotechnical Engineering Services. PSC

GEOTECHNICAL ENGINEERING REPORT FOR

PERIMETER FENCE FOR

VETERANS AFFAIRS CARIBBEAN HEALTHCARE CENTER

RIO PIEDRAS, PUERTO RICO

1.0 INTRODUCTION

This report presents the results of the subsurface exploration performed along the perimeter of the

Veterans Affairs Caribbean Center, in Rio Piedras, Puetio Rico. The work was performed at the request of Architect Enery M. Dorta, RA, partner of Gautier & De Torres, Arquitectos & Ingenieros, designers of the project.

The purpose of the exploration was to establish the physical properties of the underlaying subsurface soil in order to evaluate and recommend the soil parameters required for the design of the foundation system of the proposed perimeter fence. The subsoil exploration and laboratory analyses were performed by GEOTECHNICAL ENGINEERll'\G SERVICES, PSC under the supervision of the undersigned, following the terms of our proposal dated June 18, 2013.

2.0 SITE LOCATION AND PROJECT DESCRIPTION

The site of the project is located along the entire perimeter ofthe facilities of the Veterans Affairs

Caribbean Healthcare Center, bounded by State Road PR-21 , Maga Street, Cacia Street, and Center

Medic Facilities, in Monacillo Ward, Rio Piedras, Puerto Rico. Topography along the perimeter is rolling, where the fence will run along leveled areas, lowland areas, and along the crest of steep slopes. Most of the site is covered with grass, exposed in-situ soils, or dumped fills. Figure 1, included on an Appendix to tllis report, shows the location of the project.

!\1 ~( 3.:$3. S.\~ Jt \!':.P.R. 009!6-6023 PHONE 1\(). (787) {1~8-122-l ~A X l'\( ). (7l'i71 75.5·6tl~3

PERIMETER FENCE FOR VA CARIBBEAN HEAL THCARE CENTER

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The proposed project consists of the construction of an ornamental fence, some 10 to 15 feet high, with concrete columns and ornamental steel. No grading plan was made available to us at the date of this report but as per visual inspec6on, it seems that the san1e topography will be kept along the alignment of the fence. Probably, some spots will need upgrading fills and other spots might require minor cuts' operations.

3.0 WORK PERFORMED

Eleven ( 11) borings to depths of 8 to mostly 10 feet, were drilled along the perimeter of the healthcare center. Figure 2, present a site plan of the existing facilities, with the borings drilled approximately depicted on it. Due to access restriction, all borings were drilled using a portable motorized cathead mounted on an aluminum denick tripod.

Laboratory tests were conducted on most of the soil samples secured in order to obtain Natural

Moisture Content and Unconfined Compressive Strength, according to the applicable ASTM

Designations. The data was then evaluated in order to prepare the foundations recommendations for the proposed structure.

4.0 GENERAL SITE GEOLOGY

The site has been mapped as part of the Geologic Map of the San Juan Quadrangle, prepared for the

U.S. Geological Survey by M.H. Pease and Watson H. Momoe in 1977 (USGS Miscellaneous

Investigation Series Map # I -101 0).

According to the USGS, most of the facilities are located over the San Sebastian Formation

(Middle Oligocene). The San Sebastian Formation consists of sandy clay containing pebbles and cobbles of silicified volcanic rock, grades upward into thin bedded fine sand and red and gray mottled clays.

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Figure 3, shows a portion of the San Juan Geologic Quadrangle with the site approximately depicted on it.

5.0 SUBSOIL CONDITIONS

5.1 Perimeter of VA Healtlzcare Center (Borings I, 3, 4, 5, 6, 7, 9, and 1 1)

Some of the borings discussed in this section disclosed various layers of old fill material, sampled mainly as; Clayey gravel (Boring 4 from 0 to 2 feet), Medium plastic silty clay (Boring 9 from 0 to

4 feet) , and Silty sand followed by high plastic clayey fills with trace gravel (Boring 11 from 0 to 4 feet). Consistency of the fine-grained layers varied from stiffto very stiff. Coarse grained layers exhibited Standard Penetration Test N-values varying from 2 to 48 blows per foot, which represent a very loose to medium dense state of relative density. The natural moisture content ofthe samples secured ranged from 14 to 22 percent.

Underlaying the erratic fill at Borings 4, 9, and 11 and from ground surface at the rest of the borings discussed in this section, the San Sebastian Formation was encountered, sampled as interbedded layers of; Medium to High plastic silty clay with different amounts of sand, Low plastic silt, with different amounts of sand, and medium plastic clayey silt. Consistency of the clayey layers, based on Standard Penetration Test N-values and unconfined compressive strength data varied from soft

(Borings 1 and 4) to hard. The natural moisture content of the samples secured ranged from 13 to

45 percent, and the unconfined compressive strength values varied from 0.5 to 4.5 tons per square foot. The low plastic silt layers with trace to some sand, showed Standard Penetration Test N-values varying from 11 to 28 blows per foot, which represent a medium dense state of relative density. This horizon extends to the full depth drilled.

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5.2 Zones of Concern (Borings 2, 8, and 1 0)

AUGUST 25,2014

PAGE4

These three borings revealed an erratic fill horizon thru almost the entire depth of drilling. Boring

2, revealed in the upper 4 feet, a deposit of very stiff sandy clay, with some gravel, roots, and garbage. Underlaying the upper heterogeneous fill layers of medium dense low plastic silts were found from 4 to 6 feet and from 8 to 10 feet. From 6 to 8 feet, a fill layer of very dense silty sand with little gravel was found.

At Boring 8, the upper 2 feet of fill consisted of a soft, high plastic silty clay, with trace gravel and sand, followed from 2 to 8 feet, of another fill stratum sampled as; Silty sand, fine to coarse grained, with little subangular gravel. Standard Penetration Test N-values varied from 23 to 54 blows per foot, which represent a medium to very dense state of relative density.

At Boring 10, from 0 to 4 feet, a fill material sampled as; Medium dense, silty clayey sand, fine to coarse grained, with little gravel, was found. From 4 to 6 feet, another fill layer consisting of coarse subangular gravel, was found. Relative density was loose. From 6 to 8 feet, the fill material changed to high plastic silty clay with some sand, and little subangular gravel. Consistency was soft. Finally, from 8 to 10 feet, the in-situ soil was found sampled as; Dense silty clayey sand.

6.0 GROUNDWATER

Although some samples were found moist or wet, no steady groundwater level was detected, within the range of depth drilled. It is not possible to properly determine the groundwater level within the normal scope of the test hole exploration, especially in frne grained soils. Observation wells are needed in order to determine the presence of groundwater within a reasonable setting time.

Therefore, the water levels observed during the drilling operations may not indicate the true position of the existing groundwater table.

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7.0 GENERAL

AUGUST 25,2014

PAG£5

The above information is a general description of the subsoil conditions at the site. For detailed information on the soil characteristics at and along the boreholes, at the time and under the conditions these were drilled, refer to the boring logs which are included on an Appendix to this report.

The depths mentioned in this report, unless otherwise specified, are referred to the existing ground surface elevations prevailing during the drilling phase of this project.

8.0 DISCUSSION

Several constructions are being developed constantly during the past decades within the premises of the VA Caribbean Healthcare facilities, hence it is typical that depressions, unlevel areas, or excavations, outside of main structures were backfilled with dumped old fills, construction debris, or non appropriately, using non-selected fills or selected fills with poor compaction energy. This condition is observed at Borings 2, 8, and 10, and in a lesser degree at Borings 4, 9, and 11 .

Moreover, the San Sebastian Formation is an erratic geological formation, with different weathering stages and types of soils, including silts, sands, and mainly clayey silts and silty clays, with heterogeneous consistency.

Hence, most of the perimeter fence will require susburface treatments, consisting of undercutting and backfilling properly, to create a well-compacted base material to cast new footings . Likewise, there are some specific zones, where drainage gullies will be crossed by the fence, hence some kind of bridge structure will be required. Finally, the section of the perimeter fence running at the crest of steep slopes, which show erosion problems, will need to be cast over some type of drilled pylons, to affect the less possible, the slopes with large excavations for footings.

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Two foundation alternatives will be presented to transmit the loads of the fence columns, to the improved underlaying soi ls. First, isolated, strip, or combined shallow footings, cast deep enough, by-passing the old fill materials at some portions of the alignment, or over new selected fills at others.

Second, to use cast in place caissons, with suggested diameters varying from 24, 30, and/or 36 inches for the sections of the wall running at the crests of slopes, or near underground utilities, or where the lack of space does not allow a shallow footing. Minimum depth of embedment should be in the order of 15 feet, below the existing grade, or finish grade, depending which one is lower.

9.0 ENGINEERING RECOMMENDATIONS

9.1 Shallow Foundations Alternative

It is not possible to exactly predict where or how deep along the wall alignment dumped material

(garbage, construction debris, etc.) and poor bearing old fills will be encountered. This should be determined directly at the field , during earthwork operations. The performance of exploratory test pits (with a digger) is recommended to assess this condition. Special attention should be given at the area of Borings I (poor bearing in-situ soils), 2, 4, 8, 10, and 11.

These fill deposits and the in-situ soils at some sectors, are not capable of withstanding the loads, to be imposed by this practically small wall without suffering large amounts of settlement or even a bearing capacity fai lure. An improvement of the underlaying old fill soil shall be made. The improvements shall consist of an over excavation of the about upper six ( 6) feet or twice the width of the footing, whichever is greater, of said fill material and replace it with A-2-6 or A-2-4 selected material. This material should be compacted in layers ( 12" thick) to at least 95% (Modified Proctor) of their maximum dry density. This subsurface treatment will be made at least at the wall alignment covered by Borings 1, 2, 4, and I 0.

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Once the bottom of such excavation has been reached, the soil inspector, shall perform a series of test pits to corroborate depth of removal. If no more removal is necessary then backfilling can be started with the selected fill.

The excavation shall be planned so that run-off is controlled via a sump pit at its end.

The excavation shall be made following the criteria presented on Fi2Ure 4.

A geotextile shall be installed at the bottom of excavation prior to any fill placement to uniform the settlements and reduce the intrusion of backfill into the soft soil. A Mira:fi BXG-12, Tensar BX 1200, or similar is recommended.

The footings may be dimensioned on the basis of an allowable soil bearing pressure of 2,500 psf.

Depth of foundation (Dr) shall not be shallower than 2 feet below existing grade, after subsurface treatment.

The rest of the wall alignment covered by Borings 3, 6, 7, and 9, the footings may be dimensioned for the same allowable soil bearing pressure of 2,500 psf, but with a depth of foundation (Dr) not shallower than 3 feet below existing grade.

Footings adjacent to existing down slopes (Bming 5) should be separated from later by a minimum horizontal distance of 4 feet between the outer edge of the footing and the crest of the slope, Fi2ure

~. Slopes shall be heavily protected against erosion.

For loads of short duration, such as seismic or wind loads, the recommended soil bearing pressures can be increased by 33 percent.

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PAGES

All foundation excavation bases shall be inspected and released by a geotechnical technician prior to the actual cast of the concrete. At certain locations, over excavation and backfilling might be required.

It is important, that the foundation bottom not be disturbed or softened due to poor excavation procedures, because this could lead to an unanticipated source of significant settlement.

A differential settlement in the orderof0.5 of an inch between nearby footings, should be considered in the design.

Final depth of casting shall be determined by uplift load requirements.

The following soil parameters can be used for the uplift resisting load estimates;

Unit Weight (pet) for an A-2-6 fill material

Angle with the vertical to defme volume of soil cone resisting uplift

Lateral Earth Pressure Coefficient

Angle of Internal Friction (<p)

Cohesion (ksf)

Factor of Safety against uplift

*After Bowles, 1988, page 228

The old fill material should not be used as backfill.

MSC 343 SAN JUAN. PUERTO RICO 0092().6023

115 pcf

( 45 - <p/2)

1.3*

28° (A-2-6)

2.5

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9.1.1 Temporary Excavations

A UGUST 25,2014

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Excavations of about 6 feet are expected at the site. Our calculations indicate that a slope ratio of

1:1 (H: V) up to a depth of 10 feet should be used to reach an adequate factor of safety (FS) for the temporary slopes (one week or less). A buffer zone of at least five (5) feet shall be left between the crest of the temporary slopes and any nearby structure.

However, it seems that there is no lateral space available for the implementation of safe provisional slopes (access road, sidewalks, structures). There is need to use a braced excavations. The design of the bracing system shall be performed by experts in tbis field. Also, open sloped excavations will bring large amounts of excavations and difficulty to access thru the site.

It is a well-known fact that excavations cause a change in the state of stress in the soil beside and beneath the excavated space. Such changes in stress are associated with movements of the adjacent soils and usually they have the character of settlement. If these settlements become excessive, damage to adjacent structures can be provoked.

Therefore, the design and construction of the retaining structure shall be properly performed in order to reduce settlements to a tolerable value.

Several reference points shall be established at the existing structure adjacent to the braced cuts, to indicate the trend of any movement which might affect the stability of such structures.

Lateral pressures on braced cuts cannot be calculated by the classical theories because of differences in behavior of the structure during construction. Therefore, proper technics must be used in the design of the temporary retaining structures, considering how construction is carried out. Once again, it is impmtant that the shoring system be properly designed as a temporary retaining structure.

This shall be responsibility of the General Contractor.

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Pressures resulting from uniform surcharge loads such as stockpiled earth, concentrated surface loads as cranes, trucks or other construction vehicles, and hydrostatic pressures shall be considered in the design.

The excavations shall be started only after the contractor has thoroughly planned the fmal altemative to be chosen so that delay periods are diminished, thus reducing the time the excavations remain open.

Before the excavations or undercut start, the contractor shall to submit the designer (in writing) a logical order of construction procedures and sequences to be employed, verified by his Geotechnical consultant.

Once the bottom of each excavation has been reached, the soil inspector, shall perform an inspection of the bearing surface and recommends any additional remotion if there is presence of soft and/or loose deposits. The bracing system shall be deepened considering the possibility of additional depth of excavation.

A meeting shall be held with the selected contractor prior to construction to discuss (Owner, Geotechnical Consultant, Inspection and Contractor) the construction techniques, the selected braced alternative design of system presented by contractor, the loss prevention documentation, the monitoring program, and any doubts there may be on this project. This meeting in itself is a loss prevention tool where not appropriate design or construction techniques can be singled out and eradicated prior to the construction of the temporary retention system.

Establishing reference points on adjacent structures prior to starting any excavation operation will permit measuring of any settlement that may start to occur, thus allowing to take the necessary measures to prevent such problems.

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PERJMETER FENCE FOR VA CARIBBEAN HEALTHCARE CENTER

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After footings are cast, backfilling of the excavation shall be performed on a controlled way. The fill should be compacted that the dry unit weight of the compacted material is equal to or greater than ninety-five (95) percent of the maximum unit dry weight of material compacted in the laboratory under Modified Proctor Compaction Test. 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 corr-esponding dry density of every type of fill material to be used by the contractor in order to properly evaluate the percentage of compaction of the fill material.

The contractor should employ suitable equipment, to obtain the required percentage of 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 eight (8) inch 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 should overlap the preceding adjacent pass by ten ( 1 0) percent. Roller passes made on material in unsuitable condition will not be considered in judging compliance with our recommendations. In case the Contractor fails to obtain the required compaction energy, he must get the appropriate type of equipment to comply with this compaction criterion.

The acceptability of the compaction will be established by tests (state weathered at Contractor's or

Owner's expense) . The unit weight of compacted material will be established by nuclear testing procedures, in accordance to ASTM requirements. Additional tests to establish or confum maximum Proctor Density, optimum moisture content and percentage stone content will be performed as required by working conditions.

Samples of all potential sources of fill must be submitted to the soil laboratory to establish their adequacy. Borrow materials for fill should consist of essentially granular material (GW, GM, SW, MSC 343 SAN JliAN, PUERTO RICO 00926--6023 PHONE NO. (787) 648-2224 FAX NO. (7871 755-6643

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SP, or SM, Unified Soil Classification System; or A-2-6 to A-1 -a AASHTO Classification System), as approved by the Geotechnical Engineer. These should be free from vegetable matter and should not contain rocks having a dimension greater than six (6) inches. The in-situ soils shall not be used as backfill.

9.2 Cast in Place Caissons Alternative

Table 1, present tension and compression capacity for 24, 30, and 36 inches diameter caissons cast at 15 feet deep.

TABLEl

Suggested Ultimate Ultimate Pile Shaft Factor of Safety Depth of Tension Compression Type Dimension Analysis Capacity Capacity

(inches) End Skin (feet) (kips) (kips) Bearing Friction

Drilled 24 (2.0') 2 2 15 13 22

Drilled 30 (2.5') 2 2 15 15 29

Drilled 36 (3.0') 2 2 15 17 35

The following recommendations shall form part of the design of the cast in place caissons.

~ SHAFT 24, 30, OR 36 fNCHES JN DIMENSION AND PREDRILLED.

~ TEMPORARY CASING SHOULD BE ANTICIPATED BY CONTRACTORS BTDDING THE JOB.

~ APPROXIMATE LENGTH OF CAISSON lS 15 FEET, MEASURED FROM EXISTING GROUND

SURFACE AT THE TIME OF OUR INVESTIGA TJON.

~ FOR LATERAL LOADED CAISSONS, PLEASE REFERS TO SECTION 9.2.2.

~ WE RECOMMEND THAT STRUCTURAL DESIGNER IS DIRECTED TO ARTICLE 4.6,

"DRILLED SHAFT" OF THE AASHTO INTERIM GUIDE, AND OTHER STRUCTURAL

C01\SIDERA TIONS ABOUT CAISSONS.

R IO PIEDRAS, PUERTO RICO

AUGUST 25,2014

.,. THE CONTRACTOR SHALL BE ADV1SED OF THE NEED TO A VOID CAVING OF HOLES, THIS

EFFECT WAS EXPERJ ENCED IN OUR TEST HOLE AT DIFFERENT DEPTHS.

THIS IS A VERY SPEC IALIZED WORK, CONTRACTORS ' BIDDING THIS PROJECT, SHOULD

HAVE AT LEAST TEN YEARS OF EXPERIENCE, INSTALLING CAISSONS.

9.2.1 Considerations for Drilled Caisson Utilization

Construction of drilled shafts can be generally divided into wet and dry technics. The two processes are distinctly different. Dry hole construction allows inspection of both the full length and base of the shaft. Wet-hole construction is used, for instance, where groundwater conditions require hole stabilization. The location of the groundwater table, combined with the types of subsurface materials, dictates whether caisson construction can be drilled wet or dry.

The wet-hole casing method usually utilizes minerals (usually bentonite) or polymer mixes as a drill fluid (so-called slurry). The drilling mud assures the stability of the uncased hole while and after the drilling process. Once the hole has been drilled to the predetermined depth, the reinforcing steel is lowered into the hole and concrete is placed through a sealed tremie pipe inserted to the hole bottom.

The concrete occupying the shaft displaces the slurry mud and the operations are considered finished when relatively clean concrete appears at the top of the hole.

Although the essence of drilling and casting a caisson is relatively simple, there are certain requirements that need to be fulfilled in order to achieve good results. The following are some of the most important specifications to be required when constructing a wet-hole, drilled shaft foundation.

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,. In regard to the slurry properties, a sample taken from within one (1) foot of the bottom of the drilled shaft, immediately prior to beginning concrete operation, shall show a fluid density beMeen 65 to 75 pcf, preferably 70 pcf

The viscosity of the slurry taken with a Marsh .funnel should range from 30 to 40 seconds.

A slurry with a Marsh funnel viscosity too high are too thick and likely to have an adverse effect on the quality of drilled caisson construction.

The slurry shall be premixed prior to placing in the hole.

The slurry shall be testedfor its pH Only values between 8. 0 and 12.0 should be permitted.

Since this is a specialized work, only pre-qualifying bidders with previous job experience in similar projects should be allowed.

9.2.2 Lateral Resistance of Piles

Table 2, present recommended lateral modulus of subgrade reaction, effective unit weight, internal friction angle, undrained cohesion, and strain parameters, for the soil layers found at the site.

TABLE2

Depth Soil Type Lateral Strain Angle of Undrained Effective (feet) Modulus of Eso Internal Cohesion Unit Weight

Sub grade Friction (psi) (pcj) Reaction (pci) (fjJ)

0-15 Clayey/Silty 65 0.01 oo 250 100 Material

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A UGUST 25,2014

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The effect of repetitive loading causes the deterioration of the soil resistance under such loading conditions. By so doing, the value of "k" is also reduced. The review of the literature shows that frequent repeated loading can reduce the k-values to approximately 25 percent of the values applicable to an initial loading (1 00 percent). Using a linear relationship, the designer can estimate the reduction of the k-values depending on the frequency of his assumed lateral loads.

10.0 ADDITIONAL COMMENTS

In accordance with generally accepted construction practices, the contractor will be solely and completely responsible for working conditions at the job site, including the safety of all persons and property during the performance of the work. These requirements will apply continuously and not be limited to normal working hours. Any construction review of the contractor's performance, conducted by the Soils Engineer, is not intended to include a review of the adequacy of the contractor's safety measures, in or near the job site.

A Geotechnical Engineer shall provide continuous soil engineering services during construction of the foundation phase of the work. This is to observe compliance with the design concepts, specifications or recommendations and to allow design changes in the event that subsurface conditions differ from that anticipated prior to start of construction. Engineer selected for this purpose shall receive copy of all plans and report, evaluate them and recommend variations or additional studies as he deems necessary, thus assuming technical responsibilities of the solution herewith recommended. Copies of this report are furnished only to provide the factual data which were gathered and which were summarized in the report.

The analysis and recommendations submitted in this report are based in part upon the data obtained from the boring drilled. The nature and extent of variations between the project site may not become evident until construction. If variations then appear evident, it will be necessary to reevaluate the

MSC 343 SAN JUAN, PUERTO RJCO 00926-6021 PHONE NO. <787) 648-2224 FAX NO. (787) 755-6643

PERIMETER FENCE FOR VA CARJBBEA HEALTHCARE CENTER

AUGlJST 25, 2014

PAGE16

recommendations of this report. This IS a reason why a geotechnical inspection team is recommended.

In the event that any change in the nature, design or location of the building is planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report modified or verified in writing.

It is recommended that the soil foundation engineer be provided the opportunity for a general review of final design and specifications in order that earthwork and foundation recommendations may be properly interpreted and implemented in the design and specifications. If the soil and foundation engineer is not provided the privilege of making this recommended review, he can assume no responsibility for misinterpretation of his recommendations.

The inspection or supervision of geotechnical recommendations is a very delicate matter. In some cases this service is not rendered by the Soils Engineer who made the subsoil investigation and recommended the specific foundation alternatives for a given project. In a large number of projects these operations are successfully completed due to the prevalence of ideal and uniform conditions and to the fact that they are being performed by a competent and responsible contractor. But there are cases, where the lack of proper construction techniques and the lack of adequate supervision has given rise to the occurrence of foundation problems and failures.

This report has been prepared with the limitations above mentioned and taking into consideration the limited design factors presently known to us. The project designers shall alert us of any item that might have been overlooked, that could require clarification or those that need additional recommendations to those discussed herein.

MSC 343 SAN JUAN, PUERTO RJCO 00926-6023 PHONE NO. (787) 648-1:!24 FAX NO. (787) 755-6643

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PAGE17

The standard procedures followed during the drilling of the test boring are discussed in detail in the

Appendix to this soil report.

Geotechnical Engineer

AGR\

Reference No. 142797 August 25,2014

MSC 343 SAN JUAN. PUERTO RICO 00926-6023 PHONE NO. {787) 648-2224 FAX NO. (787) 755-6643

Geotechnical Engineering Services, PSC

II

APPENDIXES

II

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Geote{·hnical Engineering Services, PSC

APPENDIX N0.1

GENERAL

Comprised in this report is a description of the project as made known to G E S, Geotechnical

Engineering Services, PSC and details ofthe project with pertinent recommendations for the design of foundations and other earth related structures. It should be considered that the design recommendations are relative to the project aspects discussed and subject to the limitations imposed by all practical considerations in the determination of subsoil conditions.

The field and laboratory data shown in boring logs represent subsoil conditions encountered at the borehole proper. The analysis and conclusions herein presented and discussed are based on such results and on a reasonable interpolation of subsoil characteristics. Whenever cross-sections with a schematic representation ofthe interpreted subsoil stratification between borings are included, the same should not be taken to represent true intermediate conditions but are rather given for general comparison purposes only.

Copy of this report should be made available to the Project Designers for their information and guidance, as well as to the Contractor and Resident Engineer, in order to secure maximum protection in the case of possible unexpected variations. Any such variations as well as any changes or modifi cations to the scope of project described after submittance of this report shall be notified by writing to these Consultants in order to evaluate same and decide upon the need to alter or modify the recommendations given.

l\ISC J.B. SA'\ Jl'A~ . P.R. 00926-6023

Geotechnical Engineering Servk ~s. SC APPENDIX No. 2

FIELD AND LABORATORY WORK

The field work consisted of a visual observation of the area and existing structures at the site, if any, and of performance of test borings as indicated.

Test borings were made in accordance to the "Standard Penetration Test and Split-Spoon

Sampling of Soils Method" as proposed by the Standards of the American Society for testing and Materials Designation ASTM D-1586, Latest Revision.

The testing hole is bored either by manual and mechanical augers or by driving a 2.5 inch inside diameter casing into the ground which is washed clean internally each time a soil sample is to be secured below its reach. While sampling, the Standard Penetration Test is performed and the "N" values recorded. This is the number of blows required to drive the split-spoon sampler 12 inches into the ground using a 140 lbs. hammer with a free fall of 30 inches.

The value gives an indication of the consistency of cohesive soils and the relative density of granular soils as shown in the following table:

COHESIVE SOILS

"N" VALUES CONSISTENCY UNCONFINED COMP. STRENGTH {TSF)

less than 2 Very soft less than 0.25

2-4 soft 0.25-0.50

4-8 medium 0.50 - 1.00

8 - 15 stiff 1.00-2.00

15-30 very stiff 2.00-4.00 over 30 hard over 4.00 f\ISC 343. SAN JUAN. P.R. 00926-6013 PHO:\'"E ~0. (787\ 648-2224 FAX NO. mm 755-6643

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GRANULAR SOILS

"N" VALUES RELATIVE DENSITY

0-5 very loose

5 - 10 loose

10-30 medium

30-50 dense over 50 very dense

Depth of water surface shown on logs indicate the phreatic level found either prior to use of any casing and water or taken 24 hours after the test borings was completed and the casing, if any, is pulled out. The information given, unless otherwise indicated, is not a adequate for study of deep excavations and is only to be used as an approximate level in the study of a nor mal foundation of the project. Phreatic or underground water levels may vary with seasonal rainshower variations thus water may appear where none is shown and the reader of this report should be aware of this fact. For excavations where ground water levels are of utmost importance special studies consisting of long range observations on installed wellpoint-type devices should be performed. Where deep excavations are contemplated, as in pumping stations, study of artesian or sub-artesian aquifers should be made by means of deep test borings and pumping tests.

DIAMOND CORE DRILLING

Whenever drilling through rock is necessary the same is made following the "Diamond Core

Drilling for Site Investigation" method as proposed by the standards of the American Society for Testing and Materials Designation ASTM D-2113-L.R. In general a double tube core barrel with diamond bit is rotated under pressure into the rock. The drilled rock enters into

:\ lSC 343, SA~ .Jl A:-.. P.R. 00916-6023 PHO~E ·o. t 7~7 J 64S-22241".\X ,0. li87 17E.5-6643

GeJtechnica .. n~ neeru g . er 'Ices the barrel using circulating water as cooling agent. At intervals of2 to 5 feet the barrel is lifted and the core is removed. The length of each core run as well as the length of the core recovered is noted.

LABORATORY WORK

Water Contents

The natural moisture content was determined for all samples, except for those with high percentage of gravel or coarse sand.

The tests follow standards of the American Society for Testing and Materials ASTM

Designation D-2216, Latest Revision. The water or moisture content of a given soil mass is by defmition the ratio of the weight of water to the oven dry weight of the soil, expressed as a percentage.

Unconfined Compression Tests

All suitable samples of cohesive soil recovered from the split-spoon sampler were tested in unconfined compression. The ratio ofthe maximum load required for failure to the corrected cross sectional area oft he sample expressed in tons per square foot is defined as the unconfined compressive strength.

Examination and Description

Soil samples are classified according to their constituents, the foUowing terminology used to denote the approximate percentage by weight of each component.

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DESCRIPTION TERM PERCENT BY WEIGHT

Trace 1 -10

Little to some 10-20

Sandy, silty clayey 20-35

And 35-50

The examined samples are related into one of the following main groups; boulders, gravel, sand, clay, and silt. On peat, the p~esen~e of the decomposed and partly decomposed vegetable matter, is used for identification. The differentiation between a clay and a silt is based on the presence or lack of plasticity, dilatancy and dry strength rather than on grain size. The des cription of the soil includes: color, odor, minerals, presence of foreign matter, geological history, etc. These descriptions as well as the results of the laboratory testing are used in grouping similar samples into a stratigraphic unit as shown on the final boring logs.

Therefore, the data on subsurface exploration logs represent subsoil conditions at the precise locations of the boreholes only.

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FIGURES

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