CDC Exhibit A Section 01 15 00.12 10 Exploration Data 29 Sep 21.pdf

P974 Electrical System Upgrade Geotechnical Design Report

December 9, 2019

NAVFAC Atlantic

Geotechnical D esign R eport Client Name OR IN

FORMATIO

N O

NLYDecDe

NAN

EXHIBIT A - SECTION 0115 00.12 10

US Naval Base – Sheikhdom of Bahrain

Project No: 708886CH Document Title: Geotechnical Design Report Revision: 0 Date: December 9, 2019 Client Name: NAVFAC Atlantic Project Manager: Steven Andresen Author: Nicholas J. Roth, Shane M. Rasch

CH2M

One Financial Plaza 501 North Broadway St. Louis, Missouri 63102 United States T +1.314.335.4000 F +1.314.335.5104 F + 1.314.335.5141

The concepts and information contained in this document are the property of CH2M. Use or copying of this document in whole or in part without the written permission of CH2M constitutes an infringement of copyright.

Limitation: This document has been prepared on behalf of, and for the exclusive use of CH2M’s client, and is subject to, and issued in accordance with, the provisions of the contract between CH2M and the client. Jacobs accepts no liability or responsibility whatsoever for, or in respect of, any use of, or reliance upon, this document by any third party.

Document history and status

Revision Date Description Author Checked Reviewed Approved FOR pa

2M and t2M an and staandF

IN

FORMATIO

N

141 41 cument are thument are th of copyright. copyrig on behon be clcl

ONLY

US Naval Base – Sheikhdom of Bahrain

Contents

1. Project Information

2. Subsurface Conditions

2.1 Regional Geology

2.2 Provided Geotechnical Information

2.3 Water Level

2.4 Down-hole Seismic

3. Evaluation & Commentary

3.1 Shear Strengths and Compressibility of Soils

3.2 Shallow Groundwater

3.3 Demolition

4. Recommendations

4.1 Foundation Systems

4.2 Frost Penetration

4.3 Seismic Design Parameters

4.4 Floor Slabs

4.5 Lateral Earth Pressures

4.6 Earthwork

4.7 Subsurface Utilities

4.8 Roadway Subgrade

4.9 Site Excavations

4.10 Corrosion Potential

5. REFERENCES

Attachment A. Factual Report on Geotechnical Investigation Prepared by Alhoty, dated 28th Oct

Attachment B. Bearing Capacity and Settlement Calculations Attachment C. Seismic Site Class Calculation Attachment D. Liquefaction Calculations

FOR

ual Reporual Repor ngng

IN

FORMATIO

N

ONLY

US Naval Base – Sheikhdom of Bahrain

1. Project Information The P974 Substation project site is located on the NSA Bahrain Naval Base on the northeastern portion of the main island of the Sheikhdom of Bahrain near the Al Juffair Neighborhood. The general site latitude and longitude is 26.2072°N and 50.6104°E, respectively. The site currently is occupied by a one-story electrical building, a series of equipment pads and an above-grade storage tank with containment wall.

Based on the limited information available, the project includes extensive new ductbanks and manholes for the proposed 11kV distribution station, demolition of the existing P3 Substation Building 102 and constructing a new concrete structure of similar size, in the same location with a new adjacent elevated, exterior structural steel utility platform for air handling equipment. It is understood that the existing reinforced concrete, single story substation is founded on a series of spread footings.

Based on the current grading plans, minimal changes to the existing grades are anticipated. In general, utilities are expected to be installed within 1.2 m (3.9 feet) of the final grades. Table 1 below summarizes the design information that was used as the basis of this report.

Table 1 – Design Information Basis Structural Maximum/Typical Column Loads 400kN/334 kN (90 kips/75 kips)

Maximum Continuous Wall Loads 51 kN/m (3.5 kips per foot) Equipment Mat Loads Less than 178 kN (40 kips) with a maximum pad loaded area of 28 m2 (300 ft2) Building Slab Loads 14.4 kPa (300 psf) Settlement Tolerances Total: 30 mm (1-inch)

Differential:15 mm (½-in) between adjacent columns Differential:15 mm (½-in) in 10 meters (32 feet) for continuous footings

Building Code Unified Facilities Criteria (UFC) 1-200-01 change 2, 01 Nov. 2018 2015 International Building Code

Civil Finished Floor Elevation/Grading 0 to +0.15 meters (0 to ½ ft) of existing grade Below-grade Utilities 0 to -1.2 meters (0 to -3.9 feet) of existing grade

Based on the current conditions, no new pavement sections will be required for the project. It is understood that portions of the site where pavement will need to be removed as part of the construction will be replaced with a similar section to the existing section. No recommendations other than subgrade stabilization will be required for pavements.

The recommendations provided in this report are based on the above information. If there are changes to the design that are outside the limits of this report, CH2M HILL should be given the opportunity to review and revise its recommendations if needed based on the additional information. Additionally, it is understood that the existing building is being replaced for upgrading purposes and that no settlement related distress has been observed in the current structures. If there is reported distress in the existing structures, CH2M HILL should be notified to determine if further investigation or alternative recommendations are warranted.

2. Subsurface Conditions The following sections provides a general overview of the regional geology of the area based on publicly available documents and a summary of the subsurface conditions and laboratory testing program used as the basis of the recommendations provided in this report.

FOR

w-grade Uw-grade URd Floor d FlooRROR nt conditiont conditio where whe xixi

IN

FORMATIO

Nmation Bamation B 0kN/334 kN0kN/334 kNON

51 kN/m (351 kN/m (3IOLess thaLess tha area areaTI

MA141MAMAMM

FO

leleI

ONLY

oncon des are andes are an

es. Table 1es. Table

US Naval Base – Sheikhdom of Bahrain

2.1 Regional Geology

The main Island of Bahrain is positioned near the southwest portion of the Persian Gulf on the Arabian Shelf. The main island consists of a partially eroded dome of sedimentary deposits. The principal rock outcroppings are of early to middle Eocene age predominately consisting of limestone, dolomite, chalk and shales. As indicated in Figure 1 below, the edges of the island generally consist of sands and gravel overlying the bedrock. The Bahrain anticlinal axis is generally oriented in a north-south direction, running through the central portion of the main island, with no visible faults noted at the surface. The known subsurface faults are generally classified as normal tension faults.

Figure 1 - Geologic Map of Bahrain

2.2 Provided Geotechnical Information

CH2M HILL contracted with Alhoty Geotechnical to perform 3 borings to depths of 10 meters to 31 meters (32.8 feet to 101.7 feet). Based on the borings, the site is generally underlain by 4.5 to 5.5 meters of medium dense to dense sand with varying proportions of silt and gravel. The sand layer is underlain by a bedrock consisting of calcisiltite limestone (predominantly silt-size grains) that transitions to a calcilutite cement stone (predominantly clay-size grains) at approximately 16.4 meters (53.8 feet) extending to the terminal depths of the borings. The weathering of the material was variable with depth, ranging from moderately weathered to very weathered. Table 2 below briefly summarizes the range of results from the field and laboratory testing programs. Please refer to the boring logs and laboratory data in Attachment A for more specific information:

Table 2 – Summary of Subsurface Conditions

La ye r N o

Soil Strata Type A pp ro x.

D ep th s (m

St an da rd

Pe ne tra tio n, N

Fi ne s Co nt en t, Ro ck

Q ua lit y

De si gn at io n, R Q

D

1 Medium Dense to Dense Sand 0 to 5.5 6-30 5-50 --- 2 Calcisiltite Limestone 4.5 to 16.4 --- --- 19-86 3 Calcilutite Cement stone 16.4 to 31 --- --- 10-70

Site

FOR t roportiropo edominantedominant pproximatpproximat aterial waaterial wa marizemari

IN

FORMe 1 - Geole 1 - Geol al Informl Inform oty Geotecoty Geote e boringe borin nsns

US Naval Base – Sheikhdom of Bahrain

2.3 Water Level

Free water was observed in the 3 borings at depths ranging from between 1.65 meters and 2.05 meters (5.4 feet and 6.7 feet). The groundwater level at the site, will fluctuate based on variations in rainfall, evaporation, surface run-off and other related hydro-geologic factors. The water level measurements presented in this report are the levels that were measured at the time of the field activities. A summary of the observed groundwater conditions is presented in Table 3.

Table 3 – Summary of Groundwater Levels

GROUNDWATER OBSERVATIONS

Boring Ground Surface

Elevations Groundwater Depth Delayed Readings

Delayed Ground-water Elevations

BH-1 3.16 m (10.4 ft) 2.05 m after 2 Days 1.11 m (3.6 ft) BH-2 2.81 m (9.2 ft) 1.65 m on Same Day 1.16 m (3.8 ft) BH-3 2.22 m (7.3 ft) 1.85 m after 1 Day 0.37 m (1.2 ft)

In addition to the groundwater readings above, a piezometer was installed in boring BH-3 to a depth of 14 meters (46 feet). From August 31 to September 7, 2019, the reported groundwater elevation varied between elevations

0.83 meters to 0.95 meters (2.7 feet to 3.1 feet).

2.4 Down-hole Seismic

Alhoty Geotechnical performed down-hole seismic in boring BH-1 to a maximum depth of 30 meters (98.4 feet).

Based on the stratification layers identified above, both the average compressive and shear wave velocities were determined from the arrival times. Table 4 below summarizes the calculated and interpolated values from the seismic testing.

Table 4 – Down-hole Summary

Layer No Approx. Depth (m) Average Shear Wave Bulk Unit Weight Young’s Modulus, E meters Feet m/s ft/s kN/m3 pcf MPa psi

1 6.7 22.0 297 964 18 115 314 45,530 2 16.4 53.8 431 1,414 21 134 839 121,655 3 30 98.4 551 1,807 21 134 1,440 208,800

3. Evaluation & Commentary Based on the geotechnical and project information available, CH2M HILL has identified three (3) geotechnical items that will control the behavior of the proposed

1. The shear strength and compressibility of the upper soils will control the behavior of the proposed grade supported structures.

2. Based on the proposed depth of the utilities, shallow groundwater was encountered that may require dewatering for the installation of the utilities.

3. The debris resulting from the demolition of the existing structures should be removed from the site and replaced with an engineered backfill.

FOR RR

Fe

22.022.0RO4 54 OR

FO0 0 FOFFO

IN

FORMATIO

Ns instals insta d groundwd groundw mic in borimic in bo bove, both bove, both

4 below s4 below s

TableTable

IN(m) NANNININt IN

ONLYY

1.YLYNL

ONONON

edd

US Naval Base – Sheikhdom of Bahrain

3.1 Shear Strengths and Compressibility of Soils

The primary geotechnical property controlling the bearing capacity and compressibility of the above grade structures is the shear strength of the underlying sands. In general, the overburden sandy soils are anticipated to behave as a cohesionless material. Base on the in-situ field testing, the overburden materials are anticipated to have shear strengths represented by friction angles ranging from 30 to 32 degrees. Limited unconfined compressive testing was performed in underlying bedrock. Based on the RQD and compressive strength data, CH2M HILL would anticipate the underlaying bedrock to have a minimum undrained shear strength of 0.5 MPa (10,000 psf). These values will be used as the basis of the recommendations provided below.

3.2 Shallow Groundwater

The groundwater surface was noted to be as shallow as 0.4 to 1 meter (1.3 to 3.3 feet) below the existing grades.

It is understood that a majority of the utility work will be performed within 1.2 meters (3.9 feet) feet of the ground surface; therefore, localized dewatering efforts will likely be needed to provide a firm working/bedding platform.

Based on the proposed excavation, significant dewatering efforts are not anticipated. It is recommended that the ground water table not be lowered by more than 1 meters (3.2 feet). This draw down would change the stresses in the existing soils and may result in excessive settlement of the adjacent structures. If it is required to excavate deeper than the 1 meter (3.2 feet) below the existing water table, it will likely be necessary to install a series of cutoff walls or develop an installation method below the water table. The geotechnical engineer should be consulted prior to performing any deep excavations.

3.3 Demolition

It is understood that the existing building and mechanical structures will be removed or demolished to make room for the new structures. The material created as a result of the demolition should be removed from the site in its entirety as to limit the addition of soft pockets of soft uncontrolled fill or hard points in the fill, including unused foundation elements and abandoned utilities. Once the material has been removed, a controlled engineered fill should be used to establish grade on the site.

4. Recommendations The following recommendations have been prepared based on the obtained geotechnical explorations, geophysical testing and available project information previously stated in Section 1. If changes to the project occur or the field conditions are different than those noted in Section 2, modifications to the recommendations may be warranted.

4.1 Foundation Systems

Based on the anticipated loading and settlement criteria, the proposed structures should be able to be supported on conventional spread footings. Mat foundation could be used to accommodate the larger foundation systems that may be required for equipment support. Mat foundations can be designed using the subgrade modulus values outlined in Section 4.4 in conjunction with the bearing pressures stated below.

4.1.1 Shallow Foundations

The planned construction can be supported on conventional spread-type footing foundations bearing on either competent naturally deposited soil or compacted-engineered fill. Spread footings for building columns and continuous footings for bearing walls, bearing at a minimum depth of 0.8 meters (2.6 feet) can be designed for allowable soil bearing pressures of 100 kN/m2 (2,100 psf) and 90 kN/m2 (1,900 psf), respectively, based on dead

FOR ra mendatmendat ommendomm dd

IN

FORMATIO

N re eet). Theet). T the adjacethe adjace er table, it er table, it the water the water and mechand me created ascreated a soft pockeoft po oned utilitoned utilit e on the on

ONLYto 3.3 feeto 3.3 fe n 1.2 mete1.2 mete to provideo provid not antinot an is

US Naval Base – Sheikhdom of Bahrain load plus design live load. These values can be increased by 1/3 when subjected to transient loading (i.e. seismic and wind). A minimum dimension of 1,100 mm (43 inches) for square footings and 620 mm (24 inches) for continuous footings is recommended to reduce the possibility of a local bearing capacity failure.

Based on the explored subsurface conditions and site geology, laboratory testing and past experience, Jacobs anticipates that properly designed and constructed footings supported on the recommended materials should experience total and differential settlements between adjacent columns of less than 30 mm (1-inch) and 15 mm (½-inch) based on a rigid foundation, respectively. Bearing capacity and settlement calculations are included in Attachment B.

4.1.2 General Foundation Recommendations

In addition to the lateral resistances discussed in Section 4.5, the friction along the base of the footing can provide additional resistance. Based on the anticipated materials, CH2M HILL recommends a friction coefficient of 0.38 for the on-site materials and 0.47 for well-graded crushed stone.

At the time of construction, the foundation excavations should be observed by a geotechnical engineer or qualified representative prior to steel or concrete placement to assess that the foundation materials are consistent with the materials discussed in this report. Soft or loose soil zones encountered at the bottom of the footing excavations should be removed to the level of competent naturally deposited soils or properly compacted structural fill as directed by the geotechnical engineer. Cavities formed as a result of excavation of soft or loose soil zones should be backfilled with lean concrete or dense graded compacted crushed stone. The base of the foundations should be compacted prior to concrete placement.

After opening, footing excavations should be observed, and concrete placed as quickly as possible to limit the exposure of the foundation bearing surface to wetting and drying. Surface runoff water should be drained away from the excavations and not be allowed to pond. If possible, the foundation concrete should be placed during the same day the excavation is made. If it is required that footing excavations be left open for more than one day, the soils in the excavation should be protected to reduce evaporation or entry of moisture. This can be accomplished by placing an approximately 50 to 100 mm (2- to 4-inch) thick “mud mat” consisting of either non-structural or structural concrete. If this method is used, additional over-excavation should be taken into consideration to accommodate the thickness of the mud mat. The “mud mat” should also be consisted if substantial foot traffic will be required for reinforcement placement as the subgrade materials may become easily disturbed during construction.

4.2 Frost Penetration

The project region is defined as a desert region with average temperature ranging from 14°C to 40°C (57°F to 104°F); therefore, the risk of heave from frozen soil is considered very low. It is recommended that foundations be constructed at a minimal depth suitable for bearing and accommodation of adjacent structural features.

4.3 Seismic Design Parameters

According to the 2015 International Building Code (IBC), on-site soil characteristics within the upper 100 feet can be used to estimate the seismic structural design criteria for the project. CH2M HILL has reviewed the previously performed geophysical work and calculated an average shear wave velocity of 430 m/s (1,406 ft/s) in the upper 30 meters (100 feet). Calculations are included in Attachment C Based upon the recorded shear wave velocities, we recommend the use of Site Class C in accordance with ASCE 7-10. Seismic parameters and estimated ground motions are presented in Table 5 below based on the values reported in UFC 3-301-01, Change 4, 01 November 2018, Table F-3.

FOR e reqe req tion. on.

enetratioenetrati

IN

FORMATIO

N unterenter sited soilssited soil a result of eesult of cted crushcted crush served, anerved, an wetting anwetting a o pond. If pond. If t is requiret is require e protectee protecte imately 50imately 50

. If this . If thi the thicthe thic ired ired

ONLY

e basba mends amends rved by a gved by a g foundatiounda d atd t

US Naval Base – Sheikhdom of Bahrain

Table 5 –Seismic Design Parameters

DESCRIPTION VALUE

Site Classification (IBC 2015, ASCE 7-10, Chapter 20) C MCEG peak ground acceleration, PGA 0.12g Ss Spectral Acceleration for a Short Period 0.32g S1 Spectral Acceleration for a 1-Second Period 0.15g Fa Site Coefficient for a Short Period 1.20 Fv Site Coefficient for a 1-Second Period 1.65 SMs Maximum Considered Spectral Response Acceleration for a Short Period 0.38 SM1 Maximum Considered Spectral Response Acceleration for a 1-Second Period 0.25 SDS Design Spectral Response Acceleration for a Short Period 0.26 SD1 Design Spectral Response Acceleration for a 1-Second Period 0.17

4.3.1 Liquefaction

Due to the presence of a high ground water table and relatively poorly-graded sands, there is an elevated risk of liquefaction occurring in the overburden soil. Based on the anticipated ground accelerations and maximum magnitude earthquake of 7, CH2M HILL calculated factors of safety based using both the Seed (2003) and Idriss & Boulanger (2008) procedures to be greater than 1 indicating the likelihood of liquefaction to be minimal. No specific design considerations are anticipated as a result of the liquefaction potential. Liquefaction calculations are include in Attachment D.

4.4 Floor Slabs

Based on the anticipated typical slabs loads not exceeding 14.4 kPa (300 psf), the floor slab can be grade supported on the existing proof-rolled silty sands or engineered fill constructed as described in this report. Prior to steel and concrete placement, the prepared subgrades should be proof rolled with a self-propelled smooth drum roller. Soils that are observed to rut or deflect excessively (typically greater than 30-mm/1-inch) under the moving load should be undercut and replaced with properly compacted fill.

After the subgrade is prepared, it should be protected from the elements and graded to drain away from the building without low spots that can trap water. A minimum 100 mm (4-inch) thick layer of free draining granular stone should be placed beneath the floor slab to enhance drainage and provide a capillary break. Polyethylene sheeting should be also be placed to act as a vapor retarder where the floor will be in contact with moisture sensitive equipment or product such as tile, wood, carpet, etc., as directed by the design engineer. The decision to locate the vapor retarder in direct contact with the slab or beneath the layer of granular fill should be made by the design engineer after considering the moisture sensitivity of subsequent floor finishes, anticipated project conditions and the potential effects of slab curling and cracking. The floor slabs should have an adequate number of joints to reduce cracking resulting from differential movement and shrinkage.

For subgrade prepared as recommended and properly compacted fill, a modulus of subgrade reaction, k value, of (163 kPa/mm)/600 pounds per cubic inch (pci) may be used in the grade slab design based on values typically obtained from 1-foot x 1-foot plate load tests. However, depending on how the slab load is applied, the value will have to be geometrically modified. The value should be adjusted for larger areas using the following expression for cohesive and cohesionless soil:

Modulus of Subgrade Reaction, ks = ( B k

) for cohesive soil and ks = k ( B

B

)2 for cohesionless soil where: ks = coefficient of vertical subgrade reaction for loaded area, k = coefficient of vertical subgrade reaction for 1x1 square foot area B = width of area loaded, in feet Note: Formula is based on Imperial Units

FOR

hat chat eneath tneath t so be placo be pla or producor produ retarderretar afteaft

IN

FORMATIO

N tic fety basfety ba ng the likeng the like of the liquof the liqu not excenot exce sands or eands or e ared subgared subg deflect exdeflect ex ed with proed with pro

, it shou, it shou n tran tra

ONLYYLYYLYYY

y-graded sy-graded pated gated ed

US Naval Base – Sheikhdom of Bahrain

4.5 Lateral Earth Pressures

The below grade walls for the project should be designed to withstand lateral earth pressures caused by the weight of the backfill and any surcharge loads. We recommend the equivalent fluid unit weights for lateral earth pressures in Table 6 be used in the design of below-grade walls. The indicated values are based on positive drainage being provided behind walls to prevent buildup of hydrostatic pressure. Values for free-draining granular material should only be used if granular backfill extends behind the wall, upwards and outwards the full height of the wall at a slope of 45 degrees, or flatter, from its base.

Table 6 – Recommended Lateral Earth Pressures

Backfill Materials Effective Friction Angle

Est. Unit Weight

Earth Pressure Coefficients Equivalent Fluid Pressures1

At-Rest Ko

Active Ka

Passive Kp

At-Rest Active Passive2

On-Site soils 30° 18 kN/m3

114 pcf 0.50 0.33 3.00 830 Pa/m 57 psf/ft

550 Pa/m 38 psf/ft

2,500 Pa/m 171 psf/ft

Well-Graded Stone 35° 21 kN/m3

135 pcf 0.42 0.27 3.69 830 Pa/m 57 psf/ft

530 Pa/m 36 psf/ft

3,640 Pa/m 249 psf/ft

Free-Draining Crushed Stone (1-inch-clean)

32° 18 kN/m3

114 pcf 0.47 0.31 3.25 790 Pa/m 54 psf/ft

510 Pa/m 35 psf/ft

2,715 Pa/m 186 psf/ft

1. The provided fluid pressures are based on material not being saturated. If the materials are permitted to saturate, modified values will be required to account for the hydrostatic load on the wall/footing.

2. Due to the large strains required to fully mobilize the passive earth pressure, a factor of safety of 2 has been applied to the recommended passive fluid pressure.

At-rest earth pressures should be used for restrained or fixed-headed walls that are restricted from rotation, such as loading dock or basement walls connected to floor joists or beams, or a wing wall attached to a basement wall.

Active earth pressures should be used for free-headed walls where the base remains fixed and deflection at the top of the wall of approximately 10 mm per meter (1 inch for each 10 feet) of wall height is allowed, such as a retaining wall.

The above values are applicable when the surface of the backfill behind the wall is horizontal. Upward sloped or loaded backfill will result in increased values. In addition to lateral earth pressures, below-grade walls should be designed to resist any surcharge loads, including shallow building foundations and traffic. These surface loads can be modeled as uniform lateral loads, equivalent to one-half of the surface loads, acting at the halfway point on the wall. The upper 1 meter (3.2 feet) of soil backfilled against the exterior face of the walls and uncontrolled backfill soils should be ignored when calculating the lateral resistance. Lower passive pressure should be used if the ground surface slopes downward away from the face of the wall.

4.6 Earthwork

4.6.1 Site Clearing & Preparation

Prior to placement of new fills, pavements or structures, CH2M HILL recommends that the vegetation, roots, old road beds, soft, organic, frozen, and unsuitable soils in the construction areas be stripped from the site and either wasted or stockpiled for later use in non-load bearing areas. After stripping and excavating to the proposed subgrade level, as required, the building areas should be proof rolled with a self-propelled smooth drum roller.

Soils that are observed to rut or deflect excessively (typically greater than 30mm or 1-inch) under the moving load should be undercut and replaced with properly compacted fill. The proofrolling and undercutting activities should be observed and documented by a geotechnical engineer and should be performed during a period of dry weather.

FORcable cabl in increasin increas y surchargy surcharg uniform luniform l per 1 mper ii

IN

FORMATIO

N 3

1 3.21 3N TIOOOot being saot being s hydrostatichydrostat the passivthe passiv restrainedestrained ected to floected to d for free-d for free 0 mm per mm p whewh

ONLYYNLYLY

t-RestY

830 Pa830 Pa

57 57NLY

ON

69 69 88ONONO

US Naval Base – Sheikhdom of Bahrain

4.6.2 Structural Fill

Structural fill materials should be free of organic or other deleterious materials, have a maximum particle size less than three inches. Fill materials should be either non-plastic or have Liquid Limits less than 50 with a modified Proctor maximum dry density greater than 16 kN/m3 (101 pcf). Soils classified as CL, ML, CL-ML, SM, SC-SM, SW, and GW will generally be suitable for use as structural fill. Soils classified as MH, CH, GP and SP could be made suitable for use as structural fill with caution. The application of these materials should be reviewed by the geotechnical engineer prior to implementation. Soils classified as OL, OH, and PT should be considered unsuitable.

4.6.3 Compaction

The proposed structural fill should be placed in thin lifts with a maximum loose thickness of 200 mm (8 inches), then compacted in accordance with Table 7 below. The edge of the compacted fill should extend at least 2 meters (6.6 feet) beyond the outside of the proposed structures pavement edges prior to sloping. If it is necessary for the grades to be sloped within this zone, foundation element should be extended to a minimum depth of 1 unit for every unit short of the required distance, 2 meters (6.6 feet). Alternatively, retaining walls can be constructed to accommodate this grade change.

If non-cohesive soils such as the on-site sands (SP, SW), which do not exhibit a well-defined moisture-density relationship, are used as fill, they should be placed in maximum 300 mm (12-inch) thick loose lifts. A smooth-drummed vibratory roller, or other approved vibratory equipment should be used to achieve compaction of at least 70 percent relative density.

Table 7 – Recommended Compactive Effort

MATERIAL TESTED PROCTOR

TYPE

MIN %

DRY

DENSITY

MOISTURE

CONTENT

RANGE

FREQUENCY OF

TESTING*

Structural Fill (Cohesive) Modified 90% -2 to +2 % 1 per 1,000 cy of fill placed

Structural Fill (Granular) Modified 95% -2 to +2 %

1 per 1,000 cy of fill placed Rel.

Density 70% >95% Saturated

Random Fill (non-load bearing) Modified 90% -3 to +3 % 1 per 3,000 cy of fill placed

Utility Trench Backfill / Wall Backfill Modified 90% -2 to +2 % 1 per 200 cy of fill placed *Minimum of 1 test per lift

The test frequency for the laboratory reference should be one laboratory Proctor test for each material used on the site. If the borrow or source of fill material changes, a new reference moisture/density test should be performed.

Tested fill materials that do not achieve either the required dry density or moisture content range shall be recorded, the location noted, and reported to the Contractor and Owner. A re-test of that area should be performed after the Contractor performs remedial measures.

4.7 Subsurface Utilities

Utility lines should be bedded on at least 100 mm (4 inches) of granular bedding materials meeting the specifications of the pipe manufacturer or local requirements. Infiltration of water to the utility trenches must also be prevented before, during, and after construction. Excavations should not be allowed to remain open if rain is anticipated. Excavations should be backfilled with clean, suitable cohesive structural fill to minimize potential moisture infiltration. Utility trench backfill is recommended to be compacted to a minimum 90 percent of the materials modified Proctor maximum dry density at a moisture content between 0 and +2 percent of optimum.

FOR

ORRORRRORkfill /

FOOR

FOR

est per lifest p

IN

FORMATIO

N ch do nch do n mum 300 mmum 300 m ment shoument shou mmended Cmmended

ORORORMRMAMIN %

RMDR

ORMDEM

A

ORified ified OROR odified odified FOO Rel. Rel.

DensiDensFO MoMIN

ONLY

ill shoull sh or to slopior to slo ended to anded to ely, retainiy, retaini ot e

US Naval Base – Sheikhdom of Bahrain

4.8 Roadway Subgrade

Based on the currently available information, it is understood that the approximately 80 mm thick pavers, that are subjected to foot traffic, are generally underline by of 50 mm of sand over 160 mm of crushed stone. In traffic areas, the pavers are generally underline by of 50 mm of sand over 210 mm of crushed stone. It is anticipated that these materials will be disturbed during construction. Prior to replacing the paving surface, the upper 0.3 meters (1 foot) of subgrade materials should be reconditioned and compacted to a minimum of 90% of the materials’ modified Proctor. For evaluation of the proposed pavement sections, a CBR of 8 can used for design of the on-site materials after conditioning and compaction. Subsequent layers of stone and sand to be replaced should be compacted in accordance with the “Structural Fill (Granular)” requirements stated in Table 7.

4.9 Site Excavations

Excavation depths (including utility trench excavations) should in no case exceed those specified in local, state, or federal safety regulations; e.g., OSHA Health and Safety Standards for Excavations, 29 CFR Part 19266, or successor regulations. Such regulations are strictly enforced and, if not followed, the owner, the contractor, or earthwork or utility subcontractors could be liable for substantial penalties. For this site, the soils encountered generally consisted of sand. We anticipate that OSHA will classify excavations within the overburden soil as Type C. OSHA recommends a maximum slope inclination of 1½(H):1(V) for Type C soils. If any excavations, including utility trenches, are extended to depths of more than 6 meters (20 feet), OSHA requires that the side slopes of such excavations be designed by a professional engineer.

The contractor is solely responsible for designing and constructing stable, temporary excavations and should shore, slope, or bench the sides of the excavations as required to maintain stability of both the excavation sides and bottom. The contractor's "responsible person", as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations.

CH2M HILL is providing this information solely as a service to our client. CH2M HILL does not assume responsibility for construction site safety or the contractor's or other party’s compliance with local, state, and federal safety or other regulations.

4.10 Corrosion Potential

Select samples were collected from various depths of the borings and the following tests were used to determine the corrosion potential of the existing near surface soils.

Table 8 – Summary Laboratory Corrosion Analysis

Sample pH Sulfate

Chlorides

Redox (mV)

Resistivity (ohm-m)

BH-1, 1.2 m 8.8 0.31 0.04 205 94 BH-2, 0.7 m 8.4 0.43 0.05 210 361 BH-3, 0.2 m 8.7 0.29 0.13 207 291

Based on the DIPRA “Design Decision Model” point system, the above soils had Likelihood Scores of 20 to 24 (maximum value of 60) which indicates that the materials have a moderate corrosion potential to ductile iron pipe.

Depending on the DIPRA Consequence Score, various levels of coatings will be necessary to protect steel placed below grade (i.e. Polyethylene Encasement). The addition of these materials will decrease the risk of corrosion.

FOR atio

PotentiaPotent re collectee collecte al of tal o

IN

FORMATIO

N y excexc

1(V) for TV) for T ers (20 feers (20 f and constnd cons ns as requs as requ rson", as son", as ontractor's ontractor's utility tren utility tre ormation rmatio ite safetyite safety ss

ONLYxceed thoxceed tho or Excavaor Excava not followenot followe nalties. Falties. F avatioavatio

US Naval Base – Sheikhdom of Bahrain

The concentration of water-soluble sulfates is a good indicator of the potential for chemical attack on concrete.

Based on the ACI Manual of Concrete Practice (ACI 201.2R-10) or (ACI 318/318R-33), the amount of water-soluble sulfates in soil can be used to evaluate the need for protection of concrete based on Table 9:

Table 9 – Requirements for Concrete Exposed to Sulfate

Water Soluble Sulfate in soil

(percent by weight)

Sulfate Exposure Cement Requirements

0.00 to 0.10 Negligible or Class 0 Exposure None

0.10 to 0.20 Moderate or Class 1 Exposure C150 Type II

0.20 to 2.00 Severe or Class 2 Exposure C150 Type V

Over 2.0 Very Severe or Class 3 Exposure C150 Type V plus pozzolan or slag

Results of sulfate testing indicated that the sulfate levels of this site are range from 0.3% to 0.4% percent by weight and could result in degradation of the concrete if current levels are maintained. Type V cement will likely be required for construction.

5. REFERENCES

ACI 318, Building Code Requirements for Structural Concrete (ACI 318-05) and Commentary (ACI 318R-05), ACI

Committee 318, American Concrete Institute, Farmington Hills, MI, 2005

American Society of Civil Engineers. “Minimum Design Loads for Buildings and Other Structures” ASCE/SEI 7

Carter, M. & S. Bentley (1991). “Correlations of Soil Properties”. Pentech Press – London.

“The Design Decision Model” Corrpro & Ductile Iron Pipe Research Association (DIPRA), Revised May 2018DIPRA Manual

International Code Council. International Building Code. Falls Church, Va.: International Code Council, 2015.

Willis, R.P. “Geology of the Arabian Peninsula – Bahrain”. United States Department of the Interior. Geological Survey Professional Paper 560-E. 1967

Unified Facilities Criteria (UFC) 1-200-01, Department of Defense Building Code, 1 November 2018 FORil. Interna. Intern y of the Ary of the A sional Psiona

IN

FORMATIO

N

ATIOncrete (A

ATarmingto

RMA Design

FORations of S

Corrpro & rrpro

ONLY

C1C

0 Type V pType V YLYnge from 0ge from 0 maintainemaintain

US Naval Base – Sheikhdom of Bahrain

Attachment A. Factual Report on Geotechnical Investigation Prepared by Alhoty, dated 28th Oct 2019

FOR IN

FORMATIO

N O

NLY

FACTUAL REPORT ON GEOTECHNICAL INVESTIGATION

P974 ELECTRICAL SYSTEM UPGRADE

AT NSA I, JUFFAIR

KINGDOM OF BAHRAIN

REPORT NO. G18-4261

Project No. G18-4261 Rev. 0 28th October 2019 FACTUAL GEOTECHNICAL INVESTIGATION

REPORT

AIN

G18-42

G

ADE

CH2M HILL, INC.

9191 South Jamica Street, Englewood Colorado, 80112

Project: P974 Electrical System Upgrade at NSA-I, Juffair

M/s CH2M HILL, INC. have engaged M/s Al Hoty Analytical Services W.L.L (Alhoty) to carry out geotechnical investigation works for the P974 Electrical System Upgrade at NSA-I in

Juffair, Kingdom of Bahrain. This report presents the results of investigation performed for the above project.

The purpose of the investigation was to explore and evaluate the subsurface condition at various locations on the site.

Please note that all soil, rock samples, and groundwater samples (if present) will be disposed off after 30days from report submission date. In case, if the client wishes Alhoty to keep the samples for a longer period, the client should give us prior information regarding the same.

We appreciate the opportunity of providing our services for this project. If you have questions regarding this report or if we may be of further assistance, please contact the undersigned.

Sincerely, Al Hoty Analytical Services W.L.L, Gnanasai Chandra moorthy Nesa Kester Singh R Sr. Geotechnical Engineer Geotechnical Manager ical Servi ndwater date. In c t should g oviding o ay be of f he subsu

Alhoty Reference: G18-4261

Table of Contents

1 INTRODUCTION

2 SITE DESCRIPTION

3 SCOPE OF GROUND INVESTIGATION WORKS

4 REPORT FORMAT

5 GEOLOGY

6 FIELDWORK

6.1 SETTING OUT LOCATIONS

6.2 EXPLORATORY BOREHOLES

6.3 DOWN HOLE SEISMIC TEST

7 LABORATORY WORK

8 SUBSURFACE CONDITIONS

8.1 SUBSURFACE CONDITIONS

8.2 GROUNDWATER CONDITIONS

9 LIMITATIONS

10 REFERENCES

Notes Relating to Ground Investigation Reports

FOR

NCES ......CES

IN

FORMATIO

N

S

TIONSTIONS

ONLY

Appendices

Appendix A: Figure 1 – Site Location;

Figure 2 – Project Plot Location;

Appendix B: Notes regarding the interpretation of exploratory hole records

Borehole logs and Photographs of rock samples;

Appendix C: Laboratory Test Results;

Appendix D : Piezometer Monitoring Records;

Appendix E : Down Hole Shear Wave Test Results;

FOR IN

FORMATIO

N st Resultsst Results

Alhoty Reference: G18-4261

1 INTRODUCTION

NAVFAC Bahrain intends to upgrade the P974 Electrical System at NSA-I in Juffair, Kingdom of Bahrain. NAVFAC Bahrain have appointed M/s CH2M HILL, INC. / Clark

Nexsen Joint Venture as Engineering Consultant for the Contract n62470-17-D-5004.

CH2M HILL, INC. have engaged Al Hoty Analytical Services W.L.L (Alhoty) for carrying out the geotechnical investigation for the project.

The work was undertaken as per the approval of CH2M HILL, INC. in accordance with our quotation reference Q-GEO-1805204R1 dated 14th July 2018 and Professional

Services Agreement Number 148000408 dated 21st January 2019.

This report G18-4261 details the results of soil investigation undertaken at the project site at Juffair, Kingdom of Bahrain.

2 SITE DESCRIPTION

The site is located at Juffair as shown in the location plan, Figure 1 in Appendix A.

3 SCOPE OF GROUND INVESTIGATION WORKS

The overall objectives of the geotechnical investigation were to explore subsurface stratigraphy and groundwater conditions at the site to guide the design and construction of foundations and earthworks for the proposed project. This report presents the results of the geotechnical investigation performed at the site.

The main scope of ground investigation works comprised the following:

Planning and providing professional staff to supervise and liaise;

Liaising with authorities to obtain the permits;

Providing safety equipment and accessories;

Employing appropriate drilling equipment and accessories;

• Drilling 01 No. borehole to max. depth of 10m depth, 01 No. borehole to max.

depth of 16m depth and 01 No. borehole to max. depth of 31m depth below the existing ground level;

o Carrying out in-situ standard penetration tests and collection of small and bulk samples;

FOR d eard ea hnical invehnical inve cope cop

IN

FORMATIO

N he locationhe location

IGATION GATION

of the geof the ge ndwater cndwater c hwohwo

ONLYndertakenndertake o Collection of soil & water samples during drilling o Continuous coring in rock formation and;

• Laboratory tests of obtained samples.

Installation of 01 No. standpipe piezometer in drilled geotechnical borehole;

Performing 01 No. down hole shear wave test to maximum depth of 31m;

Note: Due to site constraints, field Soil Electro-resistivity has not been carried out. Since downhole shear wave test had to be carried out, piezometer was not installed in BH-1.

4 REPORT FORMAT

The report consists of the main text and appendices.

The main text includes the project description, purpose and scope of the report, background information, field investigation details and laboratory investigation details.

The Appendices include the site location map, field exploration location plan, bore logs in graphical format, laboratory test results and field test results.

FOR IN

FORMATIO

Npurposepurpos ils and labils and lab n map, fien map, fie esults and sults and

5 GEOLOGY

The main island of Bahrain consists of a partially eroded dome of sedimentary deposits of Eocene age flanked by formations of Pleistocene and Holocene.

Geological records (1) indicate that the site is likely to be underlain by the Ras Al Aqr formation.

Three main units are recognised within this formation; “caprock" (limestone and sandstone), mudflood deposits (unconsolidated soils) and carbonate rich, fine grained rocks (calcisiltite and calcilutite).

Above the Ras Al Aqr formation, shallow sediments of marine origin (clay/silt, sand, gravel, shells and shell fragments) can be expected.

FOR IN

FORMATIO

N O Nf ONLY ate rice marine marine

6 FIELDWORK

The fieldwork was performed during the period between 30th August 2019 and 18th

September 2019. All the works were performed by experienced geotechnical personnel, under the regular supervision of experienced geotechnical engineers. The fieldwork was performed in general accordance with BS5930:2015(2) Code of Practice for Site

Investigations.

All the soil & rock samples collected from the boreholes were transported to Alhoty laboratory for detailed logging and sample processing. Representative soil and rock samples were selected for laboratory testing to assist with sample descriptions and determination of engineering material properties.

6.1 Setting Out Locations

Based on the drawings issued by the client, the test locations were set out by survey team from Alhoty, refer to Figure 2 in Appendix A.

Table 6.1 – Borehole Locations

Borehole Easting, m Northing, m Elevation, m

*wrt NSD

BH-1 461129 2898688 3.16

BH-2 461122 2898670 2.81

BH-3 461109 2898659 2.22

* with respect to Bahrain National Survey Datum and approximate only

6.2 Exploratory Boreholes

A total of three (03) boreholes were drilled at the site, to a max. depth of 31m below the existing ground level. Based on the drawings provided by the client, the locations of all the drilled boreholes were identified and marked on the site by Alhoty surveyor. Drilling was performed using Drill Tech-2 hydraulic drilling rig. A combination of rotary drilling and rotary coring with mud circulation for advancing the boreholes.

FOR ROOROOspect to Bahpect to Bah

IN

FORMATIO

N the test lthe test pendix A. ndix A.

g, m g, m RMRMRMRM

461129 46112FO

46146N mple desple d

The locations of borehole BH-1 & BH-3 were paved with interlock blocks. The interlock blocks were removed carefully and reinstated after completion of works.

Standard Penetration Tests(2)(3); SPT were conducted at regular intervals in accordance with BS 1377- Part 9 : 1990 Sec 3.3.

The test involves driving a 50mm external diameter thick walled tube (Split-Barrel

Sampler) into the bottom of the borehole with successive blows of 63.5kg hammer falling freely through 760mm height. The sampler is driven through six intervals of

75mm each and the number of blows required to penetrate each interval is recorded.

The initial 150mm is intended to ensure "seating" of the sampler such that it penetrates beyond the zone of influence of any soil disturbance at the base of the borehole. The total number of blows to drive the sampler over the final 300mm is termed as the "N" value, and is considered indicative of the in-situ relative soil density.

In a very dense and/or cemented soil layers it is often not possible to ensure complete penetration of the SPT sampler, due to driving refusal, or the risk of damage to sampling equipment as a result of hard driving. Where a penetration of 300mm was not achieved, due to the density or degree of cementing of the deposit, the distance driven and number of blows were recorded on the Borehole Logs. SPT was performed wherever the soil conditions are appropriate for SPT and the N-values are reported.

Disturbed SPT and bulk samples collected during drilling were retained in sealed, labeled plastic bags.

In rock, coring was performed using PWF core barrel producing nominal core diameter of 92mm. Core runs were restricted to a maximum of 1.5m long in order to optimize core recovery. During rotary coring water mixed with bentonite was used as the flushing medium and care was taken to adjust the pressure in order to optimize core recovery. Core samples were carefully transferred from the core barrel to purpose-built wooden core boxes. Consecutive core runs were separated within the core boxes with labeled core spacers.

Details of the borehole records and the rock core sample photographs are presented in Appendix B.

FORg was peg was pe

Core run Core ru overy. ove

IN

FORMATIO

N s often nos often n driving redriving re driving. Wriving. W ree of cemree of ce ecorded oecorded o s are appare ap lk samplelk sample

ONLY

such thauch ase of thease of the

300mm is300mm is soil denoil de

One (01) No. of Piezometer was installed in borehole BH-3. Piezometer sketch followed by the piezometer monitoring records were presented in Appendix D.

6.3 Down Hole Seismic Test

One (01) down hole seismic test was performed in BH-1 up to 30m depth. The original borehole was reamed to 150mm diameter and cased with PVC casing to perform the test. The procedure adopted and the results are detailed in “Appendix E - Down hole seismic test result” section. The summary of parameters obtained from the test are summarized below in Table-6.2.

Table 6.2 – Summary Down hole seismic test results

Layer Depth

(m)

Shear

Modulus, G

(MPa)

Elasticity

Modulus, E

(MPa)

Unit weight

(kN/m3)

Poissons ratio

(μμμμ) Layer-1 6.7 158 314 18 0.48

Layer-2 16.4 390 839 21 0.48

Layer-3 30.0 638 1440 21 0.47

FOR IN

FORMATIO

N N ty

ONulus, E

TIO

N(MPa)

31431TIO

AT

MAMAMAMA

RMMAMM

ONLY

d fr s s

OOOON

UOOOONO

7 LABORATORY WORK

The laboratory testing was performed in Alhoty, ISO 17025 accredited laboratory on selected soil, rock and groundwater samples obtained during the fieldwork. The laboratory testing performed is in accordance with the relevant international standards(4)

(5) detailed under each test result as per the schedule issued by client.

The tests results can be used to classify the soils and determine the physical and strength properties of soil. Chemical test results may be used to determine the corrosion potential of the soils in order to determine the type of concrete to be used for foundation.

The following laboratory tests were undertaken in accordance with the appropriate test method;

Moisture Content;

Particle Size Distribution;

Hydrometer analysis;

Atterberg limits;

Redox potential of soil;

Resistivity of soil;

UCS test on rock samples

Chemical testing on soil & groundwater samples

The laboratory test results are presented in Appendix C.

FOR IN

FORMATIO

N l & ground& ground ults are prelts are p

ONLY

usedse with the awith the a

8 SUBSURFACE CONDITIONS

8.1 Subsurface Conditions

Details of the subsurface conditions encountered are given in the borehole logs, refer to Appendix B by referring the major description based on BS 5930:2015. Where appropriate, carbonate-rich sediments were classified according to the scheme proposed by Clark and Walker (3).

The subsurface soils encountered across the site were generally consistent and comparable with the anticipated geology of the area. Based on location of boreholes and layout of structures, a soil profile is derived as shown in Table 8.1.

Table 8.1: Subsurface Profile

LAYER DESCRIPTION Top of layer (m)

Bottom of layer (m)

Thickness of layer (m)

Loose to dense, slightly silty, gravelly, fine to medium SAND … with occasional shell, calcarenite & limestone fragments … firm silt encountered between 2.5 to 3m in

BH-2

EGL 4.5

5.5

4.5 5.5

Very stiff, slightly sandy SILT 4.5 5.5

5.4 6.25

0.9 1.75

Extremely weak to weak, CALCISITITE/

CALCILUTITE

5.4

6.25 31.0 >24.75

8.2 Groundwater Conditions

The highest water level observed in the boreholes during the course of investigation were tabulated in the table below. (refer to borehole Logs in Appendix B).

Table 8.2 – Highest Recorded Water Level in Boreholes

Borehole Water Depth, m **BEGL

Water Level, m *wrt NSD

Dates of Measurement

BH-1 2.05 1.11 02nd September 2019 BH-2 1.65 1.16 30th August 2019 BH-3 1.85 0.37 31st August 2019

**BEGL – below existing ground level * with respect to Bahrain National Spatial Datum and approximate only

These depths can be expected to reflect the prevailing levels of the groundwater table at the site which can vary according to tidal, seasonal and weather influences and local hydro-activities.

ater levater ated in theted in th

2 –2 –

IN

FORMATIO

N n n

EGLEGL

N

AT

MAAAA

SITITE/ SITITE/ RM

FO

itions tions elel

ONLY

cata le 8.1. 8.1.

BottoBott lONO

9 LIMITATIONS

The depicted subsurface conditions of this site are solely based on the drilled boreholes which are specific to their locations and provide information about a relatively small column of the soils and rock and the possibility of actual…