B08_Solicitation_SF_1442_Section_J_Attachment_6_Geotechnical_Report.pdf

GEOTECHNICAL REPORT

SALT RIVER BAY HISTORIC SITE

ST. CROIX, USVI

Submitted to:

Liollio Architecture; Aaron Bowman & Rick Bousquet

Prepared by:

Manuel E. Candelario Cosme, MSCE, PE Manuel E. Porrata Arbona, MECE, EIT

Date:

January 8, 2021

This report contains 98 pages including cover

Table of Content

1.0 INTRODUCTION:

2.0 SCOPE OF WORK AND RESULTS:

2.1 Geophysical Survey

2.2 Test Pits and Foundation Excavation

2.3 Concrete cores

2.4 Standard Penetration Test (SPT)

2.5 Dynamic Cone Penetrometer (DCP) Test

2.6 Percolation Tests:

3.0 SUBSOIL GENERALIZED CONDITIONS:

3.1 Site Geology:

3.2 Soil Stratigraphy:

3.3 Groundwater Conditions:

4.0 GEOTECHNICAL RECOMMENDATIONS:

4.1 Capacity of Existing Foundations:

4.2 Adequacy of In-situ soils:

5.0 PAVEMENT CONDITION INDEX:

6.0 FILL PLACEMENT GUIDELINES:

7.0 REPORT LIMITATIONS:

GEOTECHNICAL REPORT

SALT RIVER BAY NATIONIAL HISTORIC SITE

& ECOLOGICAL PRESERVE

VISITORS CONTACT STATION RENOVATION

ST. CROIX, USVI

1.0 INTRODUCTION:

This report presents the results of the geotechnical exploration conducted at the

Visitors Contact Station of the Salt River Bay National Historic Site and Ecological

Preserve located in St. Croix, USVI. Jaca & Sierra Engineering, PSC was contracted by Rick

Bousquet from Liollio Architecture to perform a geotechnical investigation of the existing structure, parking, driveway, and the general site area. The scope of work, based on the

Geotechnical Supplemental Scope Information developed by the National Park Service, requested the following geotechnical assessment:

Recommendations for fill placement;

Site preparation procedures;

Site stratigraphy and groundwater level;

Infiltration rate tests at selected locations;

Driveway pavement conditions assessment;

and Pavement Design.

The work consisted on pavement design, geotechnical exploration and recommendations. Figure 1 presents a satellite image of the approximate project site location.

Page 2 of 19 – Job No. 8145 St. Croix, USVI

P O B o x 3 6 3 1 1 6 , S a n J u a n , P R 0 0 9 3 6 - 3 1 1 6

( 7 8 7 ) 7 6 1 - 2 5 7 0 ( 7 8 7 ) 7 4 8 - 6 9 7 0 w w w . j a c a s i e r r a . c o m

Figure 1: Satellite Image of Project Site (17.779864°, -64.761695°) Satellite Imagery obtained from Google

Earth August 2017

2.0 SCOPE OF WORK AND RESULTS:

The fieldwork was based on the scope of work and schematic drawings of the proposed design concept prepared by others. The exploration included the following tests:

1. Geophysical Survey;

2. Test Pits and Excavations;

3. Concrete Core Extractions;

4. Standard Penetration Test (SPT) sampling;

5. Dynamic Cone Penetrometer (DCP);

6. Percolation tests.

Site

Page 3 of 19 – Job No. 8145

2.1 Geophysical Survey

The geophysical survey was carried out by means of the Ground-Penetrating

Radar (GPR) to identify any possible existing underground utilities. The area covered for the geotechnical scope consisted on the parking area and the perimeter of the structure.

Two power lines and an underground structure (presumed septic tank) were encountered by this survey. Please refer to Appendix A for aerial images with approximate location of the findings. These same findings were marked on site with flags and spray paint and were to be plotted on a site drawing by a professional land surveyor contracted by the client.

2.2 Test Pits and Foundation Excavation

Two test pits were performed near columns identified in the scope of work to measure the dimensions of the existing footings (F-1 and F-2). An additional excavation

(E-1) was also performed in the area where soil erosion was evident. The figure below shows the location of the excavations.

Page 4 of 19 – Job No. 8145

Figure 2: Approximate Locations of Footing Excavations

Table 1 presents a summary of the footing dimensions. Please refer to Appendix B for pictures and measurements taken on the field.

Table 1: Footing Dimensions

ID

Depth to Top of Footing (in)

Depth to Bottom of

Footing (in)

Footing Width (in)

Footing 1 8.00 18.00 24.00 Footing 2 10.00 17.00 24.00

Excavation-1 Not Found* Not Found* Not Found * *Footing was not encountered within the excavated depth of 4 ft below slab elevation.

Page 5 of 19 – Job No. 8145

Figure 3: Excavation Photographs (E-1)

2.3 Concrete cores

Three (3) concrete cores were extracted within the area where settlements were observed with the purpose of measuring the depth of the voids (if any) below the slab.

These cores were performed at the locations illustrated in the following figure.

Page 6 of 19 – Job No. 8145

Figure 4: Core Locations of Eroded Area

The voids below the slabs were measured to be about 20 to 23 inches below the top of the slab.

In addition, five (5) concrete cores were also extracted along the main driveway to measure the slab thickness. Cores were transported to our laboratory in Trujillo Alto, Puerto Rico to be tested for compression strength following ASTM C39. The following

Table 2 presents the length and compression strength of each core.

Page 7 of 19 – Job No. 8145

Table 2: Concrete Core Thickness Results

Core ID Thickness (in) Compression Strength (psi)

CMD - 1 8.00 5,358

CMD - 2 4.00 3,438

CMD - 3 6.00 3,464

CMD - 4 4.00 4,610

CMD - 5 5.00 2,948

2.4 Standard Penetration Test (SPT)

The SPT sampling consisted of drilling (twenty-one) 21 test borings to depths in the order of 10 feet below the existing ground surface. Subsurface sampling was carried out by the split-spoon sampler method in accordance with ASTM D1586. Accessible sites were performed following the power auger method procedure, described in ASTM

D1452. The equipment used for these locations was a CME-55 drill rig with automatic hammer. Inaccessible sites were performed with a portable derrick tripod with safety hammer.

Soil samples were secured in jars and transported to our laboratory for visual-manual description (ASTM D2488) and moisture content determination (ASTM D2216).

Also, soil classification tests (ASTM D6913 for particle size analysis and ASTM D4318 for

Atterberg limits) were performed on selected samples. The field and laboratory information are summarized in the attached boring logs presented in Appendix D.

Complete laboratory test results are presented in Appendix E.

Page 8 of 19 – Job No. 8145

The borings were identified by groups pertaining to different areas. The groups were labeled as follow:

Main Driveway - MD;

Parking Area - PA;

Perimeter - PR;

Slab with Settlement - SL.

Figures 5 and 6 present an aerial image of the approximate boring locations.

Please refer to Appendix C for the boring locations plan.

Figure 5: Boring Location Plan

Page 9 of 19 – Job No. 8145

Figure 6: Boring Location Plan (Cont.)

2.5 Dynamic Cone Penetrometer (DCP) Test

A total of thirteen (13) Dynamic Cone Penetrometer (DCP) tests were performed in accordance with ASTM D6951 throughout the existing driveway, parking area, proposed new parking area, and maintenance driveway. The DCP data was used to determine CBR values by empiric correlations. The CBR data was then used for the

Pavement Design of the Main Driveway which is included in a separate Addendum letter. The table below presents the data obtained from the DCP tests.

Page 10 of 19 – Job No. 8145

Table 3: DCP Test Summary

ID CBR (%) ID CBR (%)

DCP-1 20.0 DCP-8 35.0

DCP-2 20.0 DCP-9 40.0

DCP-3 30.0 DCP-10 50.0

DCP-4 25.0 DCP-11 65.0

DCP-5 30.0 DCP-12 60.0

DCP-6 40.0 DCP-13 40.0

DCP-7 30.0 ----- -----

2.6 Percolation Tests:

A total of six (6) percolation tests were performed on square holes of 1-ft. by 1-ft.

with a 2-ft. depth in accordance to the “Reglamento para el Control de la Inyección

Subterránea, Apéndice A, Sección E, J.C.A. (Junta de Calidad Ambiental de Puerto Rico)”, September 14, 1983. The percolation rates are calculated by the average times (T) of the column of water to drop one (1) inch (average of the last six (6) inches). The tests were performed at the locations specified by the client in order to determine the infiltration rate of the existing soil. Table 4 presents a summary of the percolation tests results.

Table 4: Percolation Test Results

Test ID Average Rate (min/in)

PE-1 29

PE-2 38

PE-3 13

PE-4 4

PE-5 14

PE-6 13

Page 11 of 19 – Job No. 8145

3.0 SUBSOIL GENERALIZED CONDITIONS:

3.1 Site Geology:

According to the U.S. Geological Survey (USGS) geologic map of St. Croix, the explored area falls within a geologic zone that corresponds to the upper cretaceous Judith

Fancy Formation (Kj). As described by the USGS geology map, this formation is characterized “by shelf and lagoon deposits based on the presence of rounded terrigenous gravel….These deposits lie stratigraphically between the Kingshill limestone and Jealousy formations…outcropping in the hills to the south.” Figure 2 presents a portion of the geologic map and the approximate site location.

Figure 7: Site Location in USGC Geologic Map1

1 Whetten, J.T., (1966) Geologic Map of St. Croix, U.S. Virgin Islands, Memoir 98, U.S. Geological Survey, U.S.

Department of Interior, Washington, D.

Site

Page 12 of 19 – Job No. 8145

3.2 Soil Stratigraphy:

The stratigraphy is composed of a medium-to-stiff upper fill which extends to a depth that ranges between 2 to 10 feet below existing ground surface. This layer is underlain by residual soils and weathered rock pertaining to the Judith Fancy Formation.

The in-situ layer is composed of a mixture of a very stiff-to-hard sandy silt and weathered rock fragments.

The strata were described as follows:

Stratum no. 1 – Fill

The upper fill is composed of a mixture of silty sand, sandy clay, silty clay with sand, gravel, and rock fragments. The data revealed that the depth of this layer ranges from 2 to 10 feet below existing ground surface. Some unexplored areas may have fill layers extending deeper than 10 feet. The SPT N-values recorded range from 4 blows per foot to refusal values (i.e. SPT N-values greater than 50 blows per 6 inches of penetration) for a medium to hard consistency.

Stratum no. 2 – Residual Soils and Weathered Rock

The fill layer overlays in-situ soils comprised of a mixture of sandy silt and weathered rock fragments. The borings revealed that this layer starts at a depth that varies from 2 feet below existing ground surface and extends until end of borings. SPT

N-values recorded range from 13 blows per foot to refusal values (i.e. SPT N-values

Page 13 of 19 – Job No. 8145 greater than 50 blows per 6 inches of penetration) for a medium to hard consistency.

Moisture contents values were up to 20%.

The following tables present a detail summary of the soil stratigraphy per boring location for three main areas defined as: Structure Perimeter, Main Driveway and Parking

Lots.

Table 5: SPT Borings Summary – Structure Perimeter

Layer Description

Layer depth (ft) per boring location

PR-1 PR-2* PR-3* PR-4* PR-5* PR-6*

Fill 0 - 4 ft 0 - 1.5 ft 0 - 9 ft 0 - 3.5 ft 0 - 2 ft 0 - 4 ft Residual

Soil ---- Not Found Not Found Not Found 2 - 3.5 ft 4 - 7.5 ft

Weathered Rock 4 - 10.5 ft Not Found Not Found Not Found Not Found Not Found

*Borings were performed with portable tripod

Table 6 presents a summary of the stratigraphy of the SPT borings performed in areas of the main and maintenance driveway.

Table 6: SPT Borings Summary - Main Driveway and Maintenance Road

Layer depth (ft) per boring location

MD-1 MD-2 MD-3 MD-4 MD-5 MD-6* MD-7*

Fill 0 - 4 ft 0 - 4 ft 0 - 4 ft 0 - 2 ft 0 - 4 ft 0 - 2 ft 0 - 2 ft Residual

Soil 4 - 9 ft 4 - 9 ft 4 - 6 ft 2 - 6 ft 4 - 9 ft 2 – 3.5 ft Not Found

Weathered Rock

9 - 10.5 ft 9 - 10.5 ft 6 - 10.5 ft 6 - 10.5 ft 9 - 10.5 ft Not Found

2 - 3.5 ft

*Borings were performed with portable tripod

Page 14 of 19 – Job No. 8145

Table 7 presents a summary of the stratigraphy of the SPT borings performed in existing and proposed parking areas.

Table 7: SPT Borings Summary – Parking

Layer depth (ft) per boring location

PA-1 PA-2 PA-3 PA-4 PA-5

Fill 0 - 4 ft 0 - 6 ft 0 - 2 ft 0 - 2 ft 0 - 4 ft Weathered

Rock 6 - 10.5 ft 6 - 10.5 ft 2 - 10.5 ft 2 - 10.5 ft 6 - 10.5 ft

3.3 Groundwater Conditions:

There was no evidence of the presence of groundwater level within the depth drilled of the borings performed. However, groundwater may rise due to long rain events. Also, perched or temporary bodies of water might be found trapped within the upper fill deposits or along the zone of transition between fill and the relatively impervious native cohesive soil strata. The groundwater data is based on observations made at the time of our fieldwork.

The presented information corresponds to a general interpretation of the subsoil conditions of the explored area. For a more detailed description regarding the soil profile, refer to the enclosed boring logs presented in Appendix D.

Page 15 of 19 – Job No. 8145

4.0 GEOTECHNICAL RECOMMENDATIONS:

The purpose of the performed geotechnical investigation was to address the following items as requested by the client:

Uncover certain existing foundations to determine dimensions;

Estimate the bearing capacity of the footings;

Provide recommendations to mitigate the settlements/erosion observed on the concrete slab around the main courtyard;

Evaluate the adequacy of insitu soils to be reused as fill;

Determine the Pavement Condition Index (PCI) of the main driveway that leads from the entrance to the visitor contact station;

Provide pavement design for various road types requested by the client.

The exploratory borings uncovered the presence of a fill material that varies in depth from 2 to 10 feet below ground. The greatest amount of fill was found on the northern and southern corner of the structure, whereas the central part of the structure was characterized by the presence of shallow weathered rock. The following figures present a schematic soil profile based on our interpretation of the geotechnical borings.

Figure 4: Schematic Soil Profile Illustrating Extent of Fill Layer

Page 16 of 19 – Job No. 8145

Figure 5: Schematic with Idealized Soil Profile

It must be noted that a localized condition was found at the location of boring PR-

3, which was performed near the courtyard. A fill material was uncovered extending to a depth of about 10 ft below ground surface. The fill was composed of silty sand with cobble-sized rock fragments and shells. Due to the limited access to the location, a portable sampling equipment was used, which has a limited driving capacity that cannot penetrate through cobbles and dense strata. For these reasons, boring PR-3 could not be advanced any further. It is possible that the fill layer extends deeper than 10 ft. The following figure presents our interpretation of the localized condition and the possible extent of the fill layer.

Page 17 of 19 – Job No. 8145

Figure 6: Possible Extent of Fill Layer Around Boring PR-3

4.1 Capacity of Existing Foundations:

The findings of the exploratory borings and the idealized soil profiles presented in the previous section were confirmed by means of test pits, which were also used to measure the footing dimensions. At the excavated locations, the footings identified as F-

1 and F-2 (refer to Figure 2), measured 24 inches wide and were found to be embedded

17 to 18 inches below ground surface (concrete slab top elevation). However, the footings near excavation E-1 could not be uncovered within the excavated depth of 4 ft. It is suspected that the columns’ footings within this area could have been embedded to the bottom elevation of the previously existing pool at around 10 ft depth since the borings

Page 18 of 19 – Job No. 8145 in this area (SL-1, SL-2, and SL-3) revealed loose fill up to 10 feet below existing ground surface. Though this would have to be confirmed by further investigations. Therefore, the bearing capacity of the footings within the eroded slab area, cannot be determined.

On the other hand, the footings near excavation F-2 were placed close to weathered rock, as revealed by boring PR-4. At this location, a net allowable bearing capacity of 3,000 psf can be assumed. However, the footings near excavation F-1 appear to have been placed over fill material, based on the findings of boring PR-3. For the columns near this area, a net allowable bearing capacity of 2,000 psf can be considered. The following figure summarizes our interpretation of the bearing capacities according to the respective locations.

Page 19 of 19 – Job No. 8145

Figure 7: Column Bearing Capacities Per Area

In addition, we recommend filling the voids under the concrete slab with lean concrete, to mitigate further damages to the concrete slab and columns, which could compromise the structural integrity of other elements. The grout mix shall consist of cement and water with a water/cement (w/c) ratio of 0.45 with the use of superplasticizers to increase grout flowability. The mix can be poured through a sealed grout injection port

(tremie pipe method). The injection pressure must be monitored so as not to exceed 15 psi. The grout injection must be coordinated with the undersigned in order to establish the locations of the injection ports and to monitor other aspects of the field work.

Legend:

Bearing capacity, qa = 2,000 psf

Bearing capacity, qa = 3,000 psf

Bearing capacity, qa = Not Determined

Page 20 of 19 – Job No. 8145

4.2 Adequacy of In-situ soils:

Laboratory testing such as soil classifications were performed on selected soil samples obtained throughout the exploratory program to evaluate the adequacy of in-situ soils to be reused as fill. The table below presents a summary of the laboratory test results.

Table 8: Laboratory Test Results

ID

Sample

Depth (ft)

USCS AASHTO

Particle Size Analysis Atterberg Limits

% Gravel % Sand % Fines LL PL PI

MD-7 0 - 2 GM A-4 (0) 34.0 29.5 36.5 NP NP NP

PE-3 0 – 2 GC A-2-4 (0) 48.1 33.5 18.4 26 16 10

PE-4 0 - 2 SC A-2-6 (0) 31.3 44.5 24.2 31 19 12

PA-5 2 - 4 SM A-1-b 33.9 43.1 23.0 NP NP NP

Most of the soil sample resulted with AASHTO soil classifications between A-2-6 and A-1, with Plasticity Index (PI) between 5 to 12 for a low plasticity. These types of soils can be reused as subbase for the new pavements. Fill must be placed following the guidelines provided in this report (Section 7.0). Materials with AASHTO classifications of A-2-4 or A-1 can be used as engineered fill on other locations. We must be consulted as to the final use of these materials in order to provide further recommendations. We encourage the performance of additional laboratory testing on bulk samples obtained from the site to further evaluate the soil classifications. Proctor compaction curve must also be performed to evaluate the maximum density of the tested samples.

Page 21 of 19 – Job No. 8145

5.0 PAVEMENT CONDITION INDEX:

The Pavement Condition Index (PCI) survey for roads and parking lots (ASTM

D6433) was used to evaluate the existing driveway. The driveway is composed of 39

Portland Cement Concrete (PCC) pavement sections. The width and length of the sections vary between 10 and 12 feet. A total 19 of the sections in order to obtain a 95% reliability, as recommended by the ASTM.

The distress types that were identified in the field survey were:

Corner Break (ID: 22) Divided Slab (ID: 23) Durability Cracking (ID: 24) Faulting (ID: 25)

The severity level (Low, Medium, or High) were assigned to each distress type following the definitions presented in the standard. Table 9 presents a summary of the field results and the deduct value (DV) obtained for each distress type with same severity level.

Page 22 of 19 – Job No. 8145

Table 9: Summary of Deduct Value Evaluation

Distress Type and Severity

Number of Slabs Where Distress

Occurred

Distress Density (%)

Deduct Value (DV)

22L 1 5% 4 22H 3 16% 35 23M 1 5% 15 23H 2 11% 32 24M 3 16% 15 24H 4 21% 40 25M 9 47% 38

The data was evaluated following an iteration process in order to calculate the maximum Corrected Deduct Value (CDV). Table 10 presents a summary of the calculations.

Table 10: Summary of Corrected Deduct Value Iteration

DV in descending order Total Deduct Value (TDV)

Iteration Coefficient

(q)

Corrected Deduct Value

(CDV) 24H 25M 22H 23H 23M 24M 25M

40 38 35 32 15 15 4 179 1 100 40 38 35 32 15 15 2 177 2 98 40 38 35 32 15 2 2 164 3 92 40 38 35 32 2 2 2 151 4 88 40 38 35 2 2 2 2 121 5 64 40 38 2 2 2 2 2 88 6 44 40 2 2 2 2 2 2 52 7 22

Page 23 of 19 – Job No. 8145

The results of the survey presented a maximum CDV of 100, therefore the

Pavement Condition Index value is 0 (PCI = 100 - Max CDV). According to the PCI rating scale (Figure 5) the existing driveway is in a “failed” condition.

Figure 8: PCI Rating Scale

(Image obtained from https://faapaveair.faa.gov/Help/PavementConditionIndexPCI.html)

Figures 6 and 7 present photographs of the most damaged slabs of the driveway.

Page 24 of 19 – Job No. 8145

Figure 9: Existing Main Driveway Entrance

Figure 10: Existing Main Driveway Section

Page 25 of 19 – Job No. 8145

6.0 FILL PLACEMENT GUIDELINES:

New paved areas will require site preparation consisting of clearing and grubbing

(i.e. removal of vegetation, topsoil, roots, and foreign debris within the upper 12 to 24 inches of subsoil). The exposed grade must then be compacted to an unyielding surface.

A proof rolling must be performed with the use of a loaded truck in order to detect any weak spots. Such spots shall be removed and replaced with selected material. Engineered fill shall then be placed up to final grade following the fill placement guidelines provided herein:

1. The fill material shall consist of well graded granular soil complying with

AASHTO Classification A-2-4 or A-1 (GM, GW, SW or SM according to

Unified Soil Classification). This material should be approved by the consultant geotechnical engineer.

a. Boulders within fill for structures should be discarded. Maximum coarse aggregate size should be 6 inches. However, fill material must be relatively well graded and should not consist of just gravel, crushed stone or poorly graded sand.

2. Fill material shall be placed in layers not exceeding eight (8) inches of thickness (as measured before compaction) on a surface free of water and each layer shall be compacted to a minimum of 95% based on its maximum dry density determined from a Modified Proctor Compaction Test, according

ASTM D 1557. If portable compaction equipment (walk-behind rollers, plate compactors, among others) will be used the thickness of the fill lift layers

Page 26 of 19 – Job No. 8145 should be reduced to 4 inches. This is required due to its relatively low compaction energy.

The construction of the fill layer shall be made under the direct supervision of the field technician. The presence of the field technician shall be continuous from the initiation of site clearing until the final grade is reached. The field technician shall confirm that the fill construction was made in conformity with these specifications.

7.0 REPORT LIMITATIONS:

Final design drawings and finish grade plan were not submitted before the submittal date of this report. Note that the recommendations in this report are based on test borings performed at specific locations, which are considered to be representative of the subsoil conditions within the project site. However, different conditions might be found during excavation and/or construction. In such instances, we must be notified to proceed with a field visual inspection in order to formulate the corresponding solution.

If this occurs, an extension of our contracted services will be requested.

In the event that the present analyzed project concept is altered, a copy of the new design must be provided to us in order to submit revised recommendations or perform additional borings, if deemed necessary. Thereafter we can evaluate additional general design and construction recommendations.

Page 27 of 19 – Job No. 8145

We wish to thank you for the opportunity of submitting this geotechnical engineering report and remain, Cordially, JACA & SIERRA ENGINEERING, PSC

Manuel E. Candelario Cosme, MECE, PE

Manuel E. Porrata Arbona, BSCE, EIT

Enclosures

Appendix A: Underground Utility Survey

Appendix B: Test Pits and Excavation

Appendix C: Boring Locations Plan

Appendix D: Boring Logs

Appendix E: Laboratory Test Results

Appendix F: Dynamic Cone Penetrometer (DCP) Locations Plan

Appendix G: Dynamic Cone Penetrometer (DCP) Test Results

Appendix H: Concrete Core Locations Plan

Appendix I: Concrete Core Thickness

Appendix J: Percolation Locations Plan

Appendix A

Underground Utility Survey

Remarks:

Legend:

Power Line

Legend:

Septic Tank

Existing underground structure (Septic Tank)

Legend:

Septic Tank

Legend:

Existing underground structure

Appendix B

Test Pits and Excavation

Appendix B: Test Pits and Excavation Location Plan

F1 F2 E1

Legend:

F1 - Footing 1 F2 – Footing 2 E1 – Excavation 1

Appendix B1: Footing 1 Remarks: Width of footing approximately 2 feet.

12 inches 21 inches

Footing 1 (F1) Footing 1 (F1)

8 inches

18 inches

Appendix B2: Footing 1

Footing 1 (F1)

14 inches

Appendix B3: Footing 2

14 inches

Footing 2 (F2) Footing 2 (F2)

10 inches

21 inches

17 inches

Appendix B4: Footing 2

10 inches

Footing 2 (F2) Footing 2 (F2)

Appendix B5: Excavation 1

81 inches

Excavation (E1) Excavation (E1)

Excavation (E1)

81 inches under existing slab

Appendix B6: Excavation 1

38 inches

Excavation 1 (E1) 20 inches

Approximately

Excavation 1 (E1)Excavation 1 (E1)

Appendix C

Boring Locations Plan

Appendix C: Boring Locations Plan

PR-1

PA-1

PA-2

MD-1

MD-2

MD-3

MD-4

MD-5

MD-6

MD-7

PA-3

PA-5

PA-4

Appendix C: Boring Locations Plan (Cont.)

SL-1

SL-2

SL-3

PA-3

PR-3

PR-4

PR-5

PR-6

PA-4

PA-5

PR-2

Appendix D

Boring Logs

FILL: silty clay with sand and gravel, light brown, olive brown

SANDY SILT some clay, stiff to very stiff, light brown, olive brown, brown (Saprolite)

WEATHERED ROCK sampled as: sandy gravel, light yellowish brown, light brown

P-1

P-2

P-3

P-4

P-5

SUBSURFACE EXPLORATION LOG

BORING No.: MD-1

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779012 -64.762767 DATE STARTED: 10-29-2020 DATE COMPLETED: 10-29-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

N-W

FILL: silty clay with sand some gravel, dark brown, brown, yellowish brown

SANDY SILT some clay, medium, very dark brown (Laterite)

SANDY SILT trace clay, hard, olive brown, light yellowish brown (Saprolite)

WEATHERED ROCK sampled as: sandy gravel some silt, yellowish brown, light brown

P-1

P-2

P-3

P-4

P-5

SUBSURFACE EXPLORATION LOG

BORING No.: MD-2

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779128 -64.762814 DATE STARTED: 10-29-2020 DATE COMPLETED: 10-29-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty clay with sand some gravel, brown, dark brown

SANDY SILT some clay, hard, light olive brown, light brown (Saprolite)

WEATHERED ROCK sampled as: sandy gravel some silt, light olive brown, pale brown

P-1

P-2

P-3

P-4

P-5

50/6"

50/3"

50/6"

50/3"

SUBSURFACE EXPLORATION LOG

BORING No.: MD-3

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779257 -64.762681 DATE STARTED: 10-29-2020 DATE COMPLETED: 10-29-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty clay with sand some gravel, dark brown, brown

SANDY SILT some clay, hard, daark brown, olive brown, light yellowish brown (Saprolite)

WEATHERED ROCK sampled as: silty sand some gravel, brown, light brown, yellowish brown

P-1

P-2

P-3

P-4

P-5

50/5"

50/2"

50/5"

50/2"

SUBSURFACE EXPLORATION LOG

BORING No.: MD-4

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779604 -64.762215 DATE STARTED: 10-29-2020 DATE COMPLETED: 10-29-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty clay with sand with gravel and rock fragments, brown, light brown, gray

SANDY SILT, hard, dusky red, light brown, grayish brown (Saprolite)

WEATHERED ROCK sampled as: silty sand with gravel, light brown, olive brown, light yellowish brown

P-1

P-2

P-3

P-4

P-5

50/5"

50/3"

50/3"

50/5"

50/3"

50/3"

SUBSURFACE EXPLORATION LOG

BORING No.: MD-5

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779721 -64.761767 DATE STARTED: 10-29-2020 DATE COMPLETED: 10-29-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: sandy silt with gravel, light brown, yellowish brown

SANDY SILT with weathered rock fragments, hard, light yellowish brown, light brown (Saprolite)

Note: Possible weathered rock at end of boring.

P-1

P-2

50/5"

50/5"

SUBSURFACE EXPLORATION LOG

BORING No.: MD-6

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / Portable Tripod COORDINATES: 17.779831 -64.762204 DATE STARTED: 11-4-2020 DATE COMPLETED: 11-4-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 3.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty clay with sand somerock fragments and concrete debris, brown, light brown

WEATHERED ROCK sampled as: sandy gravel some silt, olive brown, light yellowish brown

P-1

P-2

50/5"

50/5"

SUBSURFACE EXPLORATION LOG

BORING No.: MD-7

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / Portable Tripod COORDINATES: 17.780036 -64.761979 DATE STARTED: 11-4-2020 DATE COMPLETED: 11-4-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 3.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty sand with rock fragments, brown, dark brown

WEATHERED ROCK sampled as: sandy gravel, light brown, light yellowish brown

P-1

P-2

P-3

P-4

P-5

50/5"

50/2"

50/5"

50/2"

SUBSURFACE EXPLORATION LOG

BORING No.: PA-1

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779309 -64.762015 DATE STARTED: 10-29-2020 DATE COMPLETED: 10-29-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty sand with rock fragments, dark yellowish brown, brown, light brown

WEATHERED ROCK sampled as: sandy gravel some silt, dark grayish brown, gray

P-1

P-2

P-3

P-4

P-5

50/6"

50/6"

SUBSURFACE EXPLORATION LOG

BORING No.: PA-2

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779485 -64.762041 DATE STARTED: 10-29-2020 DATE COMPLETED: 10-29-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: sandy gravel with silt, light brown, dark yellowish brown

WEATHERED ROCK sampled as: sandy gravel some silt, dark grayish brown, gray

P-1

P-2

P-3

P-4

P-5

50/6"

50/5"

50/3"

50/2"

50/6"

50/5"

50/3"

50/2"

SUBSURFACE EXPLORATION LOG

BORING No.: PA-3

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779832 -64.761744 DATE STARTED: 10-28-2020 DATE COMPLETED: 10-28-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: sandy silt with gravel, grayish brown, olive brown

WEATHERED ROCK sampled as: sandy gravel some silt, dark grayish brown, gray

P-1

P-2

P-3

P-4

P-5

50/3"

50/3"

50/2"

50/1"

50/3"

50/3"

50/2"

50/1"

SUBSURFACE EXPLORATION LOG

BORING No.: PA-4

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779767 -64.761711 DATE STARTED: 10-28-2020 DATE COMPLETED: 10-28-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty sand with gravel, yellowish brown, light yellowish brown

WEATHERED ROCK sampled as: sandy gravel with silt, yellowish brown, light grayish brown

P-1

P-2

P-3

P-4

P-5

50/6"

50/2"

50/2"

50/6"

50/2"

50/2"

SUBSURFACE EXPLORATION LOG

BORING No.: PA-5

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779766 -64.761647 DATE STARTED: 10-28-2020 DATE COMPLETED: 10-28-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 3.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty sand with gravel, yellowish brown, light grayish brown

WEATHERED ROCK sampled as: sandy gravel some silt, brownish gray

P-1

P-2

P-3

P-4

P-5

50/4"

50/4"

50/2"

50/2"

50/4"

50/4"

50/2"

50/2"

SUBSURFACE EXPLORATION LOG

BORING No.: PR-1

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / CME-55 COORDINATES: 17.779795 -64.761976 DATE STARTED: 10-28-2020 DATE COMPLETED: 10-28-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 2.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty clay with sand some rock fragments, dark brown, brownish yellow.

P-1 3

50/3"

50/3" --

SUBSURFACE EXPLORATION LOG

BORING No.: PR-2

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / Portable Tripod COORDINATES: 17.779897 -64.761727 DATE STARTED: 11-4-2020 DATE COMPLETED: 11-4-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 2.25" ID TOTAL DEPTH (ft): 1.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: sandy clay with rock fragments, yellowish brown, light grayish brown

No Recovery on SPT sample- fill with cobble size rock fragments

7.5 FILL: silty sand some rock fragments and shells, medium, dark brown, dark yellowish brown

P-1

P-2

P-3

P-4

50/1"

50/4"

50/1"

50/4"

SUBSURFACE EXPLORATION LOG

BORING No.: PR-3

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / Portable Tripod COORDINATES: 17.779929 -64.761637 DATE STARTED: 11-3-2020 DATE COMPLETED: 11-3-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 2.25" ID TOTAL DEPTH (ft): 9

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty sand with rock fragments, medium to hard, dark brown, dark yellowish brown

P-1

P-2

50/5"

50/5"

SUBSURFACE EXPLORATION LOG

BORING No.: PR-4

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / Portable Tripod COORDINATES: 17.779921 -64.761560 DATE STARTED: 11-3-2020 DATE COMPLETED: 11-3-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 2.25" ID TOTAL DEPTH (ft): 3.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: sandy clay with silt, dark brown

SANDY SILT with weathered rock fragments some clay, hard, dark yellowish brown, dark brown (Saprolite)

P-1

P-2

50/3"

50/3"

SUBSURFACE EXPLORATION LOG

BORING No.: PR-5

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / Portable Tripod COORDINATES: 17.779843 -64.761320 DATE STARTED: 11-4-2020 DATE COMPLETED: 11-4-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 2.25" ID TOTAL DEPTH (ft): 3.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty clay with sand and gravel, dark brown, brown

SILTY SAND, medium to very dense, reddish brown, dark brown (Saprolite)

P-1

P-2

P-3

P-4

50/5"

50/5"

SUBSURFACE EXPLORATION LOG

BORING No.: PR-6

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / Portable Tripod COORDINATES: 17.779696 -64.761603 DATE STARTED: 11-4-2020 DATE COMPLETED: 11-4-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 2.25" ID TOTAL DEPTH (ft): 7.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W. Depth "Qu" - Unconfined Compressive Strength in tons per square foot. Final G.W. Depth "Rc" - Core recovery in percent for each successive run. "RQD" - Rock quality designation.

"WH" - Sample was recovered by advancing the sampler with the weight of the hammer.

"P" - A "P" in the Unconfined Compressive Strength test indicates the use of the pocket Penetrometer.

ELEV

(ft)

0.00

DEPTH

(ft) DESCRIPTION

LE

G

E N

D

S A

M P

LE

N

O

TY

P

E

B

LO

W S

SPT

N

W Qu RC RQD%

20 40 60 80

1 2 3 4Qu

FILL: silty clay with sand some rock fragments, very dark brown, grayish brown

Do... some shell fragments

Do... some shell fragments

Do... some construction debris (concrete fragments)

Note: Possible weathered rock at end of boring.

P-1

P-2

P-3

P-4

P-5

P-6

50/5"

50/5"

SUBSURFACE EXPLORATION LOG

BORING No.: SL-1

PROJECT:

Salt River Bay National Historic Site and Ecological Preserve

JOB:

OF

SHEET 1

LOCATION: ST. Croix, USVI DRILLER/DRILL RIG: J. C. Calderon / Portable Tripod COORDINATES: 17.779871 -64.761512 DATE STARTED: 11-3-2020 DATE COMPLETED: 11-3-2020

DESCRIPTION BY: Manuel Porrata SURFACE ELEVATION (ft): ND GROUNDWATER (ft): Initial: Not Found Final: ENGINEER: Manuel Candelario DRILLING METHOD: Hollow-Stem Auger 2.25" ID TOTAL DEPTH (ft): 10.5

N W Qu

"N" - Number of blows required to drive the sampling spoon a distance of 12 in. with a 140 lbs hammer falling 30 in.

"W" - Natural Moisture Content in percentage of dry weight. Initial G.W.