Amendment 5- Revised Specification Section 31 63 29.pdf

Pajaro River Flood Risk Management Project Reach 6 Contract No: W912P725BA012

SECTION 31 63 29

DRILLED CONCRETE PIERS AND SHAFTS

11/19

PART 1 GENERAL

1.1 REFERENCES

The publications listed below form a part of this specification to the extent referenced. The publications are referred to within the text by the basic designation only.

AMERICAN CONCRETE INSTITUTE (ACI)

ACI 117 (2010; Errata 2011) Specifications for Tolerances for Concrete Construction and Materials and Commentary

ACI 301 (2016) Specifications for Structural Concrete

ACI 304R (2000; R 2009) Guide for Measuring, Mixing, Transporting, and Placing Concrete

ACI 305R (2020) Guide to Hot Weather Concreting

ACI 306.1 (1990; R 2002) Standard Specification for Cold Weather Concreting

ACI 318 (2014; Errata 1-2 2014; Errata 3-5 2015;

Errata 6 2016; Errata 7-9 2017) Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14)

ACI 336.1 (2001) Specification for the Construction of Drilled Piers

ACI SP-66 (2004) ACI Detailing Manual

AMERICAN WELDING SOCIETY (AWS)

AWS A5.1/A5.1M (2012) Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding

AWS D1.1/D1.1M (2020; Errata 1 2021) Structural Welding Code - Steel

AWS D1.4/D1.4M (2011) Structural Welding Code - Reinforcing Steel

ASTM INTERNATIONAL (ASTM)

ASTM A615/A615M (2022) Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement

ASTM A1064/A1064M (2022) Standard Specification for

Final Submittal SECTION 31 63 29 Page 1 Issued for Construction August 2025

Carbon-Steel Wire and Welded Wire Reinforcement, Plain and Deformed, for Concrete

ASTM C31/C31M (2022) Standard Practice for Making and Curing Concrete Test Specimens in the Field

ASTM C39/C39M (2021) Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens

ASTM C94/C94M (2022a) Standard Specification for Ready-Mixed Concrete

ASTM C143/C143M (2020) Standard Test Method for Slump of Hydraulic-Cement Concrete

ASTM C150/C150M (2022) Standard Specification for Portland Cement

ASTM C1610 (2021) Standard Test Method for Static Segregation of Self-Consolidating Concrete Using Column Technique

ASTM C1611 (2021) Standard Test Method for Slump Flow of Self-Consolidating Concrete

ASTM C172 (2010) Standard Practice for Sampling Freshly Mixed Concrete

CONCRETE REINFORCING STEEL INSTITUTE (CRSI)

CRSI 10MSP (2018) Manual of Standard Practice

U.S. FEDERAL HIGHWAY ADMINISTRATION (FHWA)

FHWA NHI-10-016 (2010) Drilled Shafts: Construction Procedures and LRFD Design Methods

U.S. NATIONAL ARCHIVES AND RECORDS ADMINISTRATION (NARA)

29 CFR 1926.651 Specific Excavation Requirements

1.2 DEFINITIONS

1.2.1 Bearing Stratum

The soil or rock stratum that carries the load transferred to it by a pile.

1.2.2 Contract Documents

Documents covering the required Work, including the Project Drawings, Geotechnical Reports/Information, and Project Specifications.

1.2.3 Contractor

The specialty contractor who is responsible for satisfactorily performing the work described herein.

Final Submittal SECTION 31 63 29 Page 2 Issued for Construction

1.2.4 Casing Method

A method of construction in which a temporary casing is used to advance and support the sides of the borehole during the construction of the pile, including the placement of the reinforcing steel and the concrete. Natural mineral or polymer drilling fluid may or may not be used in conjunction with this method.

1.2.5 Drilling Fluid

The drilling fluid can be composed of natural mineral materials (i.e., processed clay materials such as bentonite or attapulgite), can be composed of synthetic materials (e.g., polymers or acrylamides), or can be a blend. See also: Slurry.

1.2.6 Dry Method

A method of construction in which a borehole is advanced without the use of slurry or water (as a stabilizing fluid) during the construction of the pile, including the placement of the reinforcing steel and the concrete. A temporary steel casing may be used.

1.2.7 Fully Cased

A method of construction that occurs when a temporary steel casing is used to support the borehole fully during the construction of a pile.

The casing is installed (during, before, or after excavation depending on ground or other environmental conditions) and then is extracted after placement of the steel reinforcement and concrete.

1.2.8 Ground Surface

The level at which the tooling for the construction of the pile first enters the ground. The ground surface is not necessarily the same elevation as the working platform.

1.2.9 Inspection

The observation of construction, equipment, materials, and actual subsurface conditions that enables the Geotechnical Engineer to render a professional opinion on the expected performance of the constructed work and on the Contractor's conformance to the Contract Documents.

1.2.10 Mineral Slurry

Slurry in which the principal ingredient, by weight or activity, is finely divided clay and/or other minerals.

1.2.11 Obstruction

A naturally occurring or man-made object(s) in the ground that impedes or prevents the advancement of the borehole or the installation of the pile.

1.2.12 Pig

A device inserted into a tremie pipe that is used to separate fresh, fluid concrete from the fluid(s) within the borehole excavation.

Final Submittal SECTION 31 63 29 Page 3 Issued for Construction

1.2.13 Pile or Pier or Shaft

The terms pile or pier or shaft are used interchangeably in the specifications. A vertical reinforced concrete pile, typically constructed using rotary drilling methods (including oscillator methods), which serves as the support for the proposed floodwall system and can be used for vertical loading.

1.2.14 Polymer

Water-dispersible or water-soluble water thickening compound formed from two or more polymeric compounds. Suitable polymers may potentially be synthetic, natural, modified natural, or combinations or grafts.

1.2.15 Polymer Slurry

Slurry, in which the principal ingredient, by weight or activity, is water-soluble or water-dispersible polymers.

1.2.16 Qualification

The Contractor intending to perform the construction of the Work must have had prior experience successfully installing drilled concrete piles.

1.2.17 Quality Assurance

A system or program of procedures, methods, and/or evaluations that ensure the required level of quality of and performance from the constructed work is achieved.

1.2.18 Quality Control

A system for verifying and maintaining the required level of quality in and performance from the constructed work through planning, use of proper equipment, continued observation and inspection, and corrective action.

1.2.19 Seating

The act of installing a steel casing whereby its entire circumference is in complete contact with the underlying soil/rock formation.

1.2.20 Slurry

A drilling fluid used to stabilize and support sides and bottom of the borehole during the construction of the piles. The slurry mixture provides hydrostatic pressure that supports the sides and bottom of the borehole, lubricates and cools the drill tools, and aides in cleaning or removing the cuttings from the borehole. For this type of construction, the slurry is mainly comprised of water, clay materials (e.g., bentonite or attapulgite), polymeric materials, and/or acrylamides.

1.2.21 Slurry Displacement Method

Method of drilling and concreting, whereby controlled slurry consisting of water with or without additives such as bentonite, attapulgite, or polymer is used to stabilize the borehole. The slurry may be used to stabilize an uncased drilled borehole, or to allow acceptable concrete placement when water seepage into the borehole is excessive.

Final Submittal SECTION 31 63 29 Page 4 Issued for Construction

1.2.22 Surface Casing

Temporary casing that is installed to prevent the sloughing of soil near the surface of a borehole.

1.2.23 Temporary Casing

This refers to a steel pipe that may be used to advance the borehole by supporting the sides of a borehole during the drilling and installation of the pile. The casing may be used to construct the primary and/or secondary piles, and typically provides a more consistent finished product. The casing is extracted during concreting.

1.2.24 Tremie Method

A method used to place concrete by gravity into the borehole where water and/or slurry are typically present. Concrete is placed through a conduit (i.e., steel pipe or tube) into the bottom of the borehole, and the concreting operation continues until the borehole is completely filled from the bottom up. A significant head of fresh concrete (eg. 5 to 10 feet "above fluid level in the shaft") is constantly maintained, inside and above the tip of the tremie, ensuring upward displacement of slurry and water to prevent intermixing or dilution of fresh concrete with soil, water, and/or slurry. The tremie or tube is smooth and clean both inside and out, and typically has a minimum inside diameter (ID) of 10 inches.

The pump tube typically has a minimum ID of 5 inches.

1.2.25 Wet Method

A method of construction, in which a borehole is advanced with the use of slurry or water during the construction of the pile, including the placement of the reinforcing steel and the concrete. The slurry or water is used also as a stabilizing fluid to support the sides of the borehole and to counteract hydrostatic conditions. A temporary steel casing may be used also with this method.

1.2.26 Working Platform

A surface that safely supports the construction equipment and personnel.

The working platform also includes any ramps, access paths, and roads.

1.3 SUBMITTALS

Government approval is required for submittals with a "G" designation.

Submittals not having a "G" designation are for information only. When used, a designation following the "G" designation identifies the office that will review the submittal for the Government. "SPN" - San Francisco District.

Submit the following in accordance with Section 01 33 00 SUBMITTAL

PROCEDURES:

SD-01 Preconstruction Submittals

Dimensions and Alignment of Borehole

Fabrication and Lifting Plan

Final Submittal SECTION 31 63 29 Page 5 Issued for Construction

Installation Plan ; G, (SPN)

SD-02 Shop Drawings

Drilled Shaft Diameters ; G

Depth of Test Holes ; G, (SPN)

Top and Bottom of Shaft Elevations ; G, (SPN)

Steel Reinforcement ; G, (SPN)

Anchor Bolt Locations ; G, (SPN)

Accessories ; G, (SPN)

SD-05 Design Data

Mix Design Data ; G, (SPN)

SD-06 Test Reports

Soils Report ; G, (SPN)

Ground Water Conditions

Slump ; G, (SPN)

Concrete ; G, (SPN)

Compressive Strength ; G, (SPN)

Work Record

SD-07 Certificates

Bill of Lading for Ready-Mix Concrete Deliveries

Steel Reinforcement ; G, (SPN)

Welding Certificates ; G

Excavation and Drilling Equipment ; G, (SPN)

Qualifications of Contractor ; G

1.4 QUALITY CONTROL

1.4.1 General

Install drilled pile foundations in accordance with applicable requirements as described by ACI 336.1 , and FHWA NHI-10-016 .

1.4.2 Installation Plan

Submit a detailed installation plan describing the schedule for drilling and/or excavation, installation of steel reinforcement and concrete placement with anticipated site conditions so that each excavated shaft is poured the same day that the drilling is performed.

Final Submittal SECTION 31 63 29 Page 6 Issued for Construction

a. Proposed overall construction operation sequence including procedures and methods to be used to ensure the adjacent or nearby structures and utilities are protected during the execution of the Work.

Installation plan must demonstrate how the contractor will prevent the installation of the drilled piles from affecting the performance of the sheet piles, or vice versa. The plan shall include how to monitor changes on installed piles while installing new piles and the limits of the allowed changes on installed piles.

b. Procedures and methods to be used to safeguard against loss of slurry, concrete, and/or grout into waterways, sewers, project areas, and protected areas. The proposed procedures must be in full compliance with all local, state, and federal environmental regulations.

c. Description, size, and capacities of proposed equipment, including but not limited to cranes, drills, oscillators, rotators, augers, bailing buckets, final cleaning equipment, and slurry handling equipment. The narrative must describe why the equipment was selected and describe equipment suitability to the anticipated site conditions and work methods. The narrative must include a project history of the drilling equipment demonstrating the successful use of the equipment on drilled shafts of equal or greater size/length in similar soil/rock conditions. The narrative must also include details of borehole excavation and cleanout methods.

d. Details of the method(s) to be used to ensure stability (e.g., prevention of caving, bottom heave, etc. using temporary casing, slurry, or other means) of the drilled shaft during excavation (including pauses and stoppages during excavation) and during concrete placement.

e. Detailed procedures for mixing, using, and maintaining the slurry must be provided. A detailed mix design (including all additives and their specific purpose in the slurry mix) and a discussion of its suitability to the anticipated subsurface conditions must be provided for the proposed slurry.

The submittal must include a detailed plan for quality control of the selected slurry to ensure conformance with the slurry manufacturer's recommendations and these specifications. The quality control narrative must include the test methods to be performed and the minimum and/or maximum property requirements, which must be met to ensure the slurry functions as intended for the anticipated subsurface conditions and drilled shaft construction methods. At a minimum, the slurry quality control plan must include the following tests:

Property Test

Density (pcf) Mud Weight (Density) API 13B-1, Section 1

Viscosity (seconds/quart) Marsh Funnel and Cup API 13B-1, Section 2.2

Final Submittal SECTION 31 63 29 Page 7 Issued for Construction

Property Test pH Glass Electrode, pH Meter, or pH Paper

Sand Content (percent)

1. Prior to final cleaning

2. Immediately prior to placing concrete

Sand API 13B-1, Section 5

f. Details of the concrete placement, including proposed operational procedures for pumping methods must be provided. For a drilled shaft, the Contractor must provide a sample uniform yield form to be used for plotting the approximate volume of concrete placed versus the depth of pile (except for concrete placement in the dry).

g. When drilled shafts are constructed in the wet, the submittal must include descriptions of provisions for dewatering and flooding.

h. Description and details of the storage and disposal plan for excavated material, and drilling slurry (if applicable).

i. Reinforcing steel shop drawings, details of reinforcement placement, including bracing, centering, lifting methods, and the method to assure the reinforcement position is maintained during construction.

The plan for the reinforcing steel cage assembly and installation must include:

1. Procedure and sequence for the assembly of the steel reinforcing bar cage.

2. The tie pattern, tie types, and tie wire gages for all ties on permanent reinforcing and temporary bracing.

3. Number and location of primary handling steel reinforcing bars to be used during lifting operations.

4. Type and location of all steel reinforcing bar splices.

5. Cage weight and location of the center of gravity.

6. Quantity and location of pick points used for lifting for installation and for transport (if assembled off-site).

7. Crane charts and a description and/or catalog cuts for all spreaders, blocks, sheaves, and chokers used to equalize or control lifting loads.

8. The sequence and minimum inclination angle at which intermediate belly rigging lines (if used) are released.

9. Pick point loads at 0, 45, 60, and 90 degrees, and at all intermediate stages of inclination where rigging lines are engaged or slackened.

10. Placement and type of centralizers and spacers that facilitate proper alignment and clearance of the steel reinforcement.

j. Remediation and/or corrective measures to be implemented for piles that may be out of tolerance (vertical, horizontal, and/or rotational). Provide a mitigation procedure for concrete segregation, tremie pipe breaks, etc.

1.4.3 Inspection Criteria

Design inspection activities to minimize delays while insuring the intent

Final Submittal SECTION 31 63 29 Page 8 Issued for Construction of the Industry Standard Specifications.

1.4.4 Qualification of Contractor

The proposed Work must be accomplished by Contractors and skilled workers thoroughly experienced in the necessary crafts and having relevant experience with the anticipated subsurface materials, water conditions, installation equipment, drilled shaft dimensions, and any special techniques required. In some cases, pre-qualification may be required to ensure that qualified, experienced contractors perform the work. Approval of the Contractor, its personnel, equipment, methods, etc. is subject to satisfactory field performance. Documentation containing satisfactory proof of compliance must be submitted by the Contractor for approval and must include:

a. Not less than three successfully completed and documented projects within the past five years where the Contractor performing the work has successfully installed concrete reinforced drilled piles similar to the size, length, and type to be installed on the project. Provide relevant details describing the equipment and methods used, details pertaining to any difficulties encountered, and how the difficulties were overcome. Include the complete contact information for at least one reference for each project cited.

b. The name and experience record for the Contractor's on-site supervisor for this work. The experience record must include, at a minimum, a record of successful installation of concrete reinforced drilled piles on at least two projects in the most recent 5 to 10 years.

c. The name and experience record for the Contractor's drilling operator for this work. Include, at a minimum, two years of experience installing concrete reinforced drilled piles with similar diameters and lengths, and in similar ground conditions using a technology similar to that proposed for this work. The experience record must include a record of successful installation of concrete reinforced drilled piles on at least two projects in the most recent 5 to 10 years.

Submit certificates substantiating the Qualifications of Contractor .

1.4.5 Welding Qualifications

Provide and maintain qualified procedures and personnel according to AWS D1.1/D1.1M , AWS D1.4/D1.4M , and AWS A5.1/A5.1M . Submit Welding Certificates to the Contracting Officer.

1.4.6 Pre-Construction Conference

After submittals are received and approved but before drilled shaft excavation and foundation work, including associated work, is performed, the Contracting Officer will hold a pre-construction conference to review the following:

a. The drawings, specifications and the geotechnical report.

b. Finalize construction schedule and verify availability of materials, Excavator's personnel, equipment, and facilities needed to make progress and avoid delays.

Final Submittal SECTION 31 63 29 Page 9 Issued for Construction

c. Methods and procedures related to drilled shaft foundation installation, including engineer's written instructions.

d. Support conditions for compliance with requirements, including alignment between foundation system and erection of structural members.

e. Governing regulations and requirements for, certificates, insurance, tests and inspections if applicable.

f. Temporary protection requirements for foundation assembly during and after installation.

1.5 PROJECT CONDITIONS

1.5.1 Existing Conditions

Locate existing underground utilities before excavating drilled shaft foundations. If existing utilities are to remain in place, provide protection during drilled shaft operations.

1.5.2 Interruption of Existing Utilities

Do not interrupt any utility to occupied facilities unless directed in writing by the Contracting Officer.

1.5.3 Weather Limitations

Proceed with installation preparation only when existing and forecasted weather conditions permit work to proceed without water entering into the area of excavation.

PART 2 PRODUCTS

2.1 DESIGN REQUIREMENTS

Submit design data for the following:

a. Mix design data in accordance with paragraph READY-MIX CONCRETE accompanied by the Bill of Lading for Ready Mix Concrete deliveries .

2.1.1 Assembly

Installation drawings are to include, but not limited to, the following items indicating a completely dimensioned layout and location of drilled shafts and concrete placement for foundation system. Submit detailed shop drawings for the following:

a. Drilled shaft diameters

b. Depth of test holes

c. Top and bottom of shaft elevations

d. Steel reinforcement

e. Anchor bolt locations

f. Accessories

Final Submittal SECTION 31 63 29 Page 10 Issued for Construction

2.2 EQUIPMENT

2.2.1 Drilling and Excavation Equipment

Provide drilling and excavation equipment having adequate capacity, including but not limited to, power, torque and down thrust to excavate a hole of diameter and depth indicated. Also provide excavation and over-reaming tools of adequate design, size and strength to perform the work indicated.

Provide special drilling equipment including, but not limited to, rock core barrels, rock tools, air tools and other equipment as necessary to construct the shaft excavation to the size and depth indicated when materials encountered can not be drilled using earth augers and/or over-reaming tools.

Submit certificates substantiating appropriate selection of excavation and drilling equipment .

2.3 MATERIALS

2.3.1 Steel Reinforcement

2.3.1.1 Deformed Steel Bars

Steel bars conforming to ASTM A615/A615M , Grade 60 ksi and ACI 318 .

2.3.1.2 Plain Steel Wire

Steel wire conforming to ASTM A1064/A1064M .

2.3.2 Centralizers and Spacers

Non-corrosive centralizers and spacers that facilitate proper alignment of the steel reinforcement must be used.

2.3.3 Ready-Mix Concrete

Ready-Mix concrete and mix design conforming to ACI 117 , ACI 301 , and ACI 304R , minimum compressive strength 4,500 psi at 28 days. Slump results between 5 to 6 inches, according to ASTM C143/C143M for dry methods .

For concrete placed in wet holes using the tremie or pump method, an increased slump in the range of 7 to 9 inches (as measured by ASTM C143/C143M) is permitted, in accordance with ACI 336.1 and FHWA NHI-10-016 , when utilizing high-range water-reducing admixtures (HRWR, i.e., superplasticizers), and if necessary, viscosity-modifying admixtures (VMAs) to ensure mix stability and resistance to segregation.

The mix design shall demonstrate adequate cohesion and resistance to washout under wet placement conditions.

Alternatively, self-consolidating concrete (SCC) may be proposed for wet hole placement. When SCC is used, the concrete shall achieve a slump flow spread of 18 to 22 inches per ASTM C1611, and the mix shall meet all specified strength, durability, and stability requirements.

All wet method concrete mixes (including SCC) shall be supported by laboratory and field test data verifying performance, including, but not limited to, tests for segregation, bleeding, resistance to washout, and

Final Submittal SECTION 31 63 29 Page 11 Issued for Construction flow.

Contractor shall submit the proposed concrete mix design including admixtures and applicable test results, including static segregation test according to ASTM C1610 with a percent static segregation less than 10%, for approval prior to use in wet method/tremie applications.

Portland cements conforming to ASTM C150/C150M, Type II or V. Provide one brand and type of cement for formed concrete having exposed-to-view finished surfaces.

Potable water conforming to ASTM C94/C94M.

Measure, batch, mix and deliver concrete according to ASTM C94/C94M and furnish batch ticket information.

2.3.4 Casing

The temporary casing must be steel, rigid, smooth, clean, and capable of withstanding all handling, installation, and extraction stresses. The temporary casing must be capable of withstanding the pressures exerted by the infill concrete, groundwater, and the surrounding soil and/or rock.

The outside diameter (OD) of the temporary casing must be at least the required size of the vertical pile. The temporary casing must be of sufficient length (partial or full length of pile) to provide temporary support to achieve the required length for each pile within the Work. If segmental casing is used, the segments must be connected by using flush-bolted, reasonably watertight, casing joints.

2.3.5 Mineral Slurry

Mineral slurries must be used in conformance with the manufacturer's recommendations and the quality control plan specified in the Pile Installation Plan section of this specification. The mineral slurry must conform to the following requirements:

Property Test Requirements

Density (pcf) Mud Weight (Density) API 13B-1, Section 1

63 to 75

Viscosity (seconds/quart) Marsh Funnel and Cup API 13B-1, Section 2.2

26 to 50 pH Glass Electrode, pH Meter, or pH Paper

8 to 11

Sand Content (percent)

1. Prior to final cleaning

2. Immediately prior to placing concrete

Sand API 13B-1, Section 5 4.0 (max)

4.0 (max)

At the time of testing, the temperature of the slurry must be at least 40°F.

Final Submittal SECTION 31 63 29 Page 12 Issued for Construction

2.3.6 Synthetic Slurry

Synthetic slurries must be used in conformance with the manufacturer's recommendations and the quality control plan specified in the Pile Installation Plan section of this specification. The synthetic slurry must conform to the following requirements:

Property Test Requirements

Density (pcf) Mud Weight (Density) API 13B-1, Section 1

64 (max)

Viscosity (seconds/quart) Marsh Funnel and Cup API 13B-1, Section 2.2

32 to 135 pH Glass Electrode, pH Meter, or pH Paper

6 to 11.5

Sand Content (percent)

1. Prior to final cleaning

2. Immediately prior to placing concrete

Sand API 13B-1, Section 5 1.0 (max)

1.0 (max)

At the time of testing, the temperature of the slurry must be at least 40°F.

2.3.7 Water Slurry

Water, with or without site soils, may be used as slurry when casing is used along the entire length of the drilled hole. The use of water slurry without full-length casing may only be used with the approval of the Contracting Officer. The water slurry must conform to the following requirements:

Property Test Requirements

Density (pcf) Mud Weight (Density) API 13B-1, Section 1

65 (max)

Viscosity (seconds/quart) Marsh Funnel and Cup API 13B-1, Section 2.2

1.0 (max)

At the time of testing, the temperature of the slurry must be at least 40°F.

Final Submittal SECTION 31 63 29 Page 13 Issued for Construction

PART 3 EXECUTION

3.1 PREPARATION

Protect existing structures, utilities, sidewalks, pavements, and other facilities from damage caused by settlement, lateral movement, vibration, and other hazards created by drilled shaft foundation operations.

Provide Fall Protection as required by Section 01 35 26 GOVERNMENTAL SAFETY REQUIREMENTS and 29 CFR 1926.651 .

3.2 INSTALLATION

3.2.1 Construction Criteria

Provide equipment for checking the dimensions and alignment of each shaft excavation. Determine dimensions and alignment jointly with the contractor, USACE Geotechnical Engineer, and Contracting Officer. Measure final shaft depths with appropriate weighted tape measure or other approved method after cleaning.

Provide and install monolithically cast-in-place concrete drilled shaft foundation to the sizes indicated.

Provide and install straight cylindrical pile foundation of the type indicated.

Tolerances:

a. Maximum variation of the center of any shaft foundation from the required location: 3 inches , measured at the ground surface.

b. Diameter: Minus zero, plus 6 inches , measured in any direction.

c. Verticality: The maximum permitted deviation of the finished drilled shaft from the vertical at any level is 1 in 100 (1%). Demonstrate the pile verticality is within the allowable tolerance. During drilling or excavation of the borehole, make frequent checks on the plumbness, alignment, and dimensions of the borehole. Any deviation exceeding the allowable tolerances must be corrected with an approved procedure.

d. Maximum bottom level: Minus 2 inches , plus 12 inches .

3.2.2 Drilled Pile Installation Methods

3.2.2.1 General

Only the method(s) submitted to, reviewed by, and accepted by the Contracting Officer may be used to construct the Work. In addition, depending upon the subsurface conditions encountered and/or Contractor performance during installation, the construction methods, equipment, personnel, etc. detailed in the Contractor's installation plan may need to be revised, as determined during consultation with the USACE Geotechnical Engineeer, at any time during the installation of the Work.

The use of full-length temporary casing may be necessary for the installation of the piles on the project. The use of permanent casing in conjunction with this work is not permitted. The Contractor must ensure that the installation/extraction of the temporary casing, if applicable, Final Submittal SECTION 31 63 29 Page 14 Issued for Construction and the placement of the concrete produce durable piles free of defects.

Secure all open drilled shaft excavations throughout the duration of the project. Drilled shafts must be protected at all times to prevent entry and must not be left open over night unless the Contractor can demonstrate the open hole is securely protected and entry is not possible.

Maintain a daily log of the construction of the secant pile wall system.

The construction log must include information pertaining to the method of installation, secant pile installation sequence and designation, borehole diameter and depth, equipment, machinery, tooling, drilling fluids, ground surface elevation, groundwater elevation, description of soil/rock/materials removed from borehole, obstructions, difficulties encountered, etc. Submit the construction logs for review, as stated in paragraph Work Records.

3.2.2.2 Dry Method

The Dry Method refers to the installation of drilled shafts using open borehole drilling or excavation where the borehole stability is ensured and is not suspect, the existing groundwater table can be controlled, and stability against bottom heave and/or blowout in the bottom of the excavation is not an issue. This method is only applicable at sites in which all of the following apply:

a. The groundwater table and subsurface conditions are suitable to permit construction of the drilled shafts in a relatively dry excavation. A "relatively dry" excavation is one in which the infiltration rate of the groundwater does not exceed 12 inches of water in one hour.

Construction operations must be performed to ensure less than 3 inches of water is present at the bottom of the borehole excavation at the time of the concrete is placed.

b. Where the sides and bottom of the borehole remain stable without any caving, sloughing, or swelling.

c. Where the sides and bottom of the borehole can be visually inspected prior to placing the reinforcing steel and concrete.

If the contractor proposes to use the dry method, two sacrificial test piles shall be constructed for each floodwall location that demonstrate the above criteria is satisfied and the contractor's methods result in an acceptable finished pile. The sacrificial piles shall be of similar depth and diameter as the design piles and each located a minimum of 100 feet from each other but within 20 feet of a design pile location.

3.2.2.3 Cased Method

The Cased Method refers to the installation of drilled shafts using temporary casing where the stability of the excavated borehole may be suspect and/or the effects of the existing groundwater cannot be controlled. The temporary casing must be installed and extracted using overhead, rotary drive equipment, or hydraulic oscillating equipment.

The installation or removal of the temporary casing by impact driving or vibratory means is not permitted.

If water is present in the borehole in excess of three inches and cannot be pumped down, placement of concrete using the free fall method is not permitted, and concrete placement using tremie methods must be used. The

Final Submittal SECTION 31 63 29 Page 15 Issued for Construction temporary casing must be removed while the concrete is still workable (i.e., before the concrete sets). As the casing is extracted, a minimum head of 5 to 10 feet of fresh concrete must be maintained within the casing, which balances all external hydraulic pressures and allows all water and fluids within the casing to be displaced upward without contaminating the fresh concrete. The temporary casing must be extracted at a slow, uniform rate along the centerline or longitudinal axis of the casing and drilled shaft.

3.2.2.4 Wet Method

The Wet Method refers to the installation of drilled shafts using slurry, other drilling fluid(s), or water to ensure sidewall stability of the borehole and/or to prevent bottom heave. If required, temporary casing may be used in conjunction with the wet method. A minimum positive head of 10 feet of fluid (i.e., slurry, other drilling fluid, or water) must be maintained above the highest level of the groundwater table to avoid bottom heave and/or blowout in the bottom of the excavation.

During excavation and concrete placement, the slurry within the borehole must conform to the requirements detailed herein. The slurry must be pre-mixed and allowed to hydrate prior to being placed into the borehole excavation. Any method in which slurry is to be prepared and mixed within the borehole excavation is not permitted. An adequate quantity of slurry tanks must be provided by the Contractor to ensure an ample supply of slurry is prepared and available during the construction and installation of each drilled shaft. Slurry pits are not permitted without prior written approval.

When applicable, a slurry circulation system composed of shakers, de-silters, de-sanders, centrifuges, pumps, etc. must be provided to maintain adequate slurry operations. Provide appropriate means to ensure adequate agitation and circulation of the slurry while it is within the borehole. The slurry mix and properties must be adjusted to ensure proper use and intended function of the slurry. To ensure proper slurry performance, the slurry must not remain un-agitated for more than 4 hours.

For drilled shafts designed to resist axial loading in side shear, the sides of the borehole must be scraped to remove any filter cake that may have formed when using mineral slurry that has not been agitated or circulated for more than 4 hours.

The wet method dictates cleaning and/or circulation (or complete replacement) of the slurry, and a final cleaning of the borehole excavation by means of a bailing bucket, air lift, submersible pump, or other devices prior to the placement of the reinforcement and concrete.

Immediately prior to the placement of the reinforcement and/or concrete, samples of the slurry must be taken from the bottom, a distance of 2 shaft diameters from the bottom, at quarter points along the length, and at a depth of 10 feet from the top of the borehole using an approved slurry sampling tool. If the slurry does not conform to the specifications, the borehole must be cleaned and the slurry must be re-circulated and/or flushed with clean, fresh slurry until subsequent tests reveal that the slurry is within the tolerances contained in the specification.

3.2.3 Steel Reinforcement

Comply with recommendations in the CRSI "Manual of Standard Practice" CRSI 10MSP for fabricating, placing and supporting reinforcement. Shop fabricate steel reinforcement in accordance with ACI SP-66 .

Final Submittal SECTION 31 63 29 Page 16 Issued for Construction

Steel reinforcement, including rebar cages or steel beam sections, must be prepared and fabricated to the dimensioning and layout detailed in the contract documents. The steel reinforcement must be fabricated, lifted, and installed in accordance with the approved Contractor fabrication and lifting plan submittal(s). Reinforcing steel cages must be wire tied (50% minimum), as required, to prevent any distortion or racking during lifting and placement. Perform the lifting and placement of the reinforcing in such a manner to ensure the safety of all persons and equipment on and adjacent to the project site.

Use the appropriate methods to ensure the reinforcing steel is centered, has the proper cover, and is properly oriented (i.e., has not distorted).

Spacers and centralizers must be used at sufficient intervals not exceeding 10 feet along the length of the reinforcement cage. A minimum of 4 spacers must be evenly spaced around the circumference of any reinforcement cage such that the maximum distance between adjacent spacers around the circumference is 24 inches. The first spacers must be placed

1.5 feet from the bottom of the drilled shaft with successive spacers at maximum intervals of 10 feet along the length of the drilled shaft. The spacers must be sized to ensure conformance with the minimum clearance required between the borehole wall and the steel reinforcement, as shown on the contract plans.

When practicable, deliver the reinforcement cage assembly to the jobsite as a complete unit ready for installation. Should it be necessary to make any additional connections and/or splices, provide as indicated on the approved shop drawings, at-grade level prior to lowering the complete assembly into the hole.

Clean reinforcement of loose rust, mill scale, earth and other foreign materials. Do not tack weld crossing reinforcing bars. Set wire ties with ends directed into concrete, not toward exposed concrete surfaces.

Lower reinforcement steel into the hole in such a manner as to prevent damage to the walls of the excavation. Place, tie and/or clip cage symmetrically about the axis of the shaft. Use centering devices securely attached to the cage to clear the shaft walls and maintain the cage in place throughout the concrete placement operations.

Cooperate with other trades in setting of anchor bolts, inserts, and other embedded items. Where conflicts occur between reinforcing and embedded items, notify the Contracting Officer in order to reconcile conflicts before concrete placement. Position and support anchors and embedded items with appropriate accessories.

Use templates to set anchor bolts, leveling plates and other accessories required for structure erection. Provide blocking and/or holding devices to maintain required anchoring positions during final concrete placement.

3.2.4 Concrete Placement

To prevent communication between boreholes and/or to prevent flow of freshly placed concrete, concrete set must be verified prior to drilling within ten feet or three shaft diameters (3D), whichever is less, from an adjacent drilled pile.

Concrete must be placed within 3 hours after excavation to ensure proper depth, cleanliness, etc. unless otherwise directed. If the concrete cannot

Final Submittal SECTION 31 63 29 Page 17 Issued for Construction be (or is not) placed within the allotted time, the borehole must be re-inspected and reapproved prior to the placement of concrete.

Immediately prior to the placement of the concrete, a check of bottom cleanliness and depth measurements must be made using a weighted tape or other methods approved by the Contracting Officer. If it is shown that more than three inches of debris or loose soil has accumulated on the bottom of the borehole, the borehole must be cleaned using appropriate and approved means.

The placement of concrete must be performed such that the elapsed time from the beginning to completion of concrete placement is kept as short as possible. The duration of concrete placement is dependent upon several variables (e.g., diameter and depth of borehole, distance to concrete plant, etc.); therefore, the duration can be estimated only on a per job basis. For drilled shafts constructed using the Wet Method, it is advisable to use a retarding agent in the concrete mix, with the contractor determining the specific dosage rates for each pour. The placement of concrete must continue in such a manner to ensure the concrete mix remains in a workable, plastic state throughout the entire concrete placement.

For drilled shafts constructed using the Dry Method, or where temporary casing results in a dry shaft, concrete may be placed using tremie, pumping, or another method approved by the Contracting Officer. Concrete must not be allowed to fall from a height greater than 5 feet .

For drilled shafts constructed using the Casing or Wet Method, concrete must be placed using the tremie, pumping, or another method approved by the Contracting Officer. Placement of concrete using the free-fall method is not permitted in conjunction with the Wet Method. At the lowermost end of the tremie pipe, a plug or similar device (e.g., a one-way flap valve, a pig, etc.) must be required to separate the fresh concrete from the fluid in the hole until pumping begins.

In conjunction with the Dry, Cased, or Wet Method, concrete pumps and tremie lines may be used for the placement of concrete under self-weight pressure. The steel tremie lines must have a minimum ID of 10 inches for a gravity system, and a minimum ID of 5 inches ID for a pumped tremie system, and must guide the concrete to the discharge point at the center of the borehole excavation. The pump lines may be flexible, but the segments and joints of the pump lines must be connected together using watertight fittings and connections. Concrete placement must not commence until the discharge orifice of the tremie line is located at the base of the borehole excavation.

To maintain a proper seal for both pumping and gravity placement and to avoid the sudden jumping of the pump line out of the poured concrete, the discharge orifice of the tremie line must be maintained at least 10 feet below the uppermost surface of the fluid concrete already placed. The concrete must be placed from the bottom of the borehole to the top surface in one continuous operation. The placement of concrete must continue until over pouring is visible at the top of the drilled shaft, and until fresh, dark grey colored concrete is easily discernible from the slurry or drilling fluid. The use of cold joints within the pile is not permitted.

Keep all equipment, including but not limited to, mixers, pumps, hoses, tools and screeds clean and free of set concrete throughout the placement operation.

Final Submittal SECTION 31 63 29 Page 18 Issued for Construction

Convey concrete from the mixer to place of deposit by best industry methods that prevents segregation and loss of material. Size and design the equipment for conveying concrete to ensure uniform, continuous placement of concrete.

Place concrete in accordance with ACI 318 .

Protect freshly placed concrete from premature drying and excessive cold or hot temperatures. When hot weather conditions exist that would impair quality and strength of placed concrete, comply with ACI 305R . Comply with ACI 306.1 for cold-weather protection.

3.3 FIELD QUALITY CONTROL

3.3.1 General

Quality control (QC) is performed by the Contractor performing the work.

Quality assurance (QA), including observation and testing, must be performed by the USACE Geotechnical Engineer.

3.3.2 Work Record

A copy of the work record of all activities performed during each work day must be submitted within 24 hours of that day's work being completed. All unanticipated drilling and/or installation conditions encountered must be included in the work record.

3.3.3 Test Reports

As a minimum, submit the following test reports and data.

a. Soils Report

b. Ground Water conditions

c. Slump

d. Concrete

e. Compressive Strength

Sample and test concrete for quality control during placement.

Sample freshly placed concrete for testing in accordance with ASTM C172.

Make concrete test specimens for compressive strength at 7 and 28 days for each design mix conforming to ASTM C31/C31M. Compression test concrete in accordance with ASTM C39/C39M.

Test Slump at plant for each design mix in accordance with ASTM C143/C143M.

3.3.4 Inspection and Monitoring

3.3.4.1 Dimensions and Alignment of Borehole

Verify and log the dimensions and alignment of each borehole excavation.

Prior to the start of construction, submit the procedures (including any equipment and tooling) that will be followed to verify the dimensions and alignment of each borehole excavation. If requested, provide a copy of

Final Submittal SECTION 31 63 29 Page 19 Issued for Construction each verification log.

3.3.4.2 Depth of Borehole Excavation

Verify and log the final depth of each borehole excavation.

3.3.4.3 Cleanliness of Bottom of Borehole

Ensure that the bottom of each borehole excavation has less than 3 inches of sediment or debris present immediately prior to the placement of the steel reinforcement and prior to the placement of concrete.

3.3.4.4 Slurry Testing

Throughout the construction of the drilled shafts, testing of the slurry must be performed in accordance with the approved submittals.

3.3.4.5 Steel Reinforcement

The steel reinforcement, including rebar cages and steel beam sections, must be fabricated, lifted, and installed in accordance with the approved fabrication and lifting plan submittal(s) and in such a manner to ensure the safety of all persons, structures, and equipment on and adjacent to the project site. Ensure and verify that the reinforcing steel is centered, has the proper cover, and is properly oriented (i.e., has not distorted).

-- End of Section --

Final Submittal SECTION 31 63 29 Page 20 Issued for Construction