31 63 21 Helical Piers.pdf

Renovate Building T111 HELICAL PIERS

VA Project No. 531-24-101 31 63 21 - 1

SECTION 31 63 21

HELICAL PIERS

PART 1 - GENERAL

1.1 DESCRIPTION

A. This section specifies excavation and concrete required for construction of helical piers.

1.2 DEFINITION

A. Helical Pier: Consists of a central steel shaft with one or more helix-shaped bearing plates and a load transfer device (bracket) that allows attachment to structures. Helical piers are installed into the ground by application of torque and axial compressive force.

1.3 RELATED WORK

A. Materials testing and inspection during construction: Section 01 45 29, TESTING LABORATORY SERVICES.

B. Subsurface investigation: Section 01 00 00, GENERAL REQUIREMENTS, Article, PHYSICAL DATA.

1.4 CONTRACTOR QUALIFICATIONS

A. Approval by COR is required of service of proposed Contractor and will be based upon submission by Contractor of certification that:

1. Contractor has technical qualifications, experience, trained personnel and facilities to install helical piers as specified.

Approval will not be given, however, where an experience record is one of unsatisfactory performance.

2. Contractor has installed helical piers on three installations similar and equivalent to this project for 5 years. Submit list of installations.

1.5 TOLERANCES

A. Locate piers where indicated by the shop drawings. The maximum permissible variation of the center of each pier from the required locations is 50 mm (2 inches) at the ground surface. No pier shall be out of required axial alignment by more than 2 percent. Periodically check the required axial alignment of each pier during the drilling operation and after reaching the required tip elevation.

1.6 DESIGN MODIFICATIONS

A. Where piers are installed exceeding specified tolerances for plumb or location. Costs for analysis, redesign, and remediation shall be responsibility of Contractor.

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B. Additional helical piers and pier cap modifications necessitated by redesign shall be furnished and installed, at no additional cost to the

Government.

1.7 SUBMITTALS

A. Submit in accordance with Section 01 33 23, SHOP DRAWINGS, PRODUCT

DATA, AND SAMPLES.

B. Certification to Examination of Site and Records: Before proceeding with the Work, submit copy of certification in acceptable form signed by the Contractor, stating that careful examination has been made of the site, existing structures, and records of utility lines, test boring records, soil samples, Drawings, and Specifications.

C. Shop Drawings and Miscellaneous Submittals:

1. Description of helical pier installation equipment.

2. Complete description of method for helical pier installation with a pier layout plan referenced to the structural plans, including a numbering system capable of identifying each individual pier, and pier sizes, including pier length. In addition, furnish a detailed description of construction procedures.

3. Pier Installation records for all helical piers.

D. Reports:

1. Installation of each pier

2. Pier location and plumbness

3. Load Test

E. Product Data: Submit copies of manufacturers’ specifications for the following products, including copies of laboratory test reports and other data as may be required to show compliance with these specifications.

1. Helical lead section

2. Helical extension section

F. Certificates: Contractor's qualifications as specified: Experienced specialty subcontractor having a minimum of 5 years successful experience installing Work of same type required for this project, and evidence of satisfactory completion of at least three helical pier installations comparable in scope of the Work and subsurface conditions. Employ only skilled tradesmen who are thoroughly experienced with the materials and equipment to be used in the Work.

G. Helical Pier Load Testing:

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1. A schedule and sequencing plan for pier testing and installation:

Contractor to submit a schedule and sequencing plan at least three weeks before commencing pier load testing.

2. Pier Load Test Work Plan:

a. At least three weeks before commencing pier load testing work, the Contractor shall submit a pier load test work plan describing the equipment, apparatus, procedures, and schedule for testing helical piers in accordance with ASTM D1143 and as specified herein, to verify the design pier capacity. The work plan shall also include the proposed instrumentation of the test pier indicating depth, location, and details of the pier.

b. As part of the Pier Load Test Work Plan, submit shop drawings and other information describing the loading and test monitoring arrangement for pier load tests, including the following:

1) Structural design of the test load support/reaction frame.

2) Details of equipment and apparatus to be used for the monitoring load and pier movements.

3) Data on testing and measuring equipment including required jack, load cell and/or gauge calibrations.

4) Sample field data recording sheets or examples of automated data acquisition records proposed for recording load test data.

H. Independent Testing and Inspection Agency: The Contractor shall retain an Independent Testing and Inspection Agency (Agency) to document, monitor, and observe load test, test pier, and production pier work.

This Agency shall submit field reports and test results required by

Section 3.2 for pier load tests and pier installations. They shall submit a pier installation report for each pier no later than three days after the installation is complete.

J. Welding Certificates.

K. Qualification Data: For Installer, Land Surveyor, and Testing and

Inspection Agency.

L. Upon completion of helical pier installations, the Contractor shall submit five copies of drawings indicating actual in-place pier locations. The Contractor shall pay for all surveying costs. Drawings must be submitted and approved prior to beginning any pier cap or mat installation. One electronic copy of the drawings shall be submitted in AutoCAD DWG format on CD-ROM.

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M. Record drawings at Project closeout according to Division 01 Section

"Closeout Procedures."

1.8 QUALITY CONTROL

A. Contractor’s Quality Control Responsibilities: Contractor is solely responsible for quality control of the Work.

B. A Quality Control Program shall be submitted by the Contractor at least three weeks prior to the commencement of work. The implementation of a

Contractor Quality Control Program does not relieve the Contractor from the responsibility to provide work in accordance with the Contract

Documents, applicable codes, regulations, and Governing Authorities.

C. Contractor's Independent Testing and Inspection Agency (Agency): The

Contractor shall retain at his own expense, the services of a qualified

Independent Testing and Inspection Agency, licensed in the state of the project, to provide testing and inspection services during the installation of all foundation piling involved in this Work. This firm shall also provide consultation services to the Contractor if problems are encountered during the execution of the Work. The Agency shall be primarily concerned with the testing and construction methods which will result in finished foundation of the required quality and strength. The Agency shall also be concerned with preventing settlement and/or damage to surrounding structures, roads, utilities, embankments, etc., both within the property lines and on adjoining properties during the construction.

D. The Agency shall be experienced in the testing and installation of helical pier foundations. It shall have been involved in at least five different helical pier projects in the last 5 years, and shall have experience in recommending, testing, and specifying helical piers for similar subsurface conditions.

E. Survey Work: The Contractor shall engage a qualified land surveyor or professional engineer to perform surveys, layouts, and measurements for helical piers. The surveyor shall record actual measurements of each helical pier location, bottom and top elevations, deviations from specified tolerances, and other specified data.

F. Welding Standards: Qualify procedures and personnel according to the following:

1. AWS D1.1

2. AWS D1.4

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G. Regulatory Requirements: Comply with applicable requirements of the laws, codes, ordinances and regulations of Federal authorities having jurisdiction. Obtain necessary approvals from such authority.

1.9 QUALITY ASSURANCE

A. The Contractor shall retain the services of a Geotechnical Consultant

(Consultant) to provide general observation of all pier operations and to provide technical advice to the Contractor with regard to pier operations and performance.

B. The Consultant shall have been involved in at least five different helical pier projects in the last 5 years, and shall have experience in recommending, testing, and specifying helical piers for similar subsurface conditions.

1.10 APPLICABLE PUBLICATIONS

A. Publications listed below form a part of this specification to extent referenced. Publications are referenced in text by basic designation only.

B. American Institute of Steel Construction (AISC)

AISC 360: Specification for Structural Steel Buildings

B. American Society for Testing and Materials (ASTM):

A36.....................ASTM A36: Carbon Structural Steel

A123....................Zinc (Hot-Dip Galvanized) Coatings on Iron and

Steel Products

A153....................Zinc Coating (Hot-Dip) on Iron and Steel

Hardware

A307....................Carbon Steel Bolts, Studs, and Threaded Rod

60 000 PSI Tensile Strength

A500....................Cold-Formed Welded and Seamless Carbon Steel

Structural Tubing in Rounds and Shapes

A513....................Electric-Resistance Welded Carbon and Alloy

Steel Mechanical Tubing

A572....................High-Strength Low-Alloy Columbian-Vanadium

Structural Steel

B633....................Electrodeposited Coatings of Zinc on Iron and

Steel

D1143...................Deep Foundations Under Static Axial Compressive

Load

D3689-07................Standard Test Method for Deep Foundations Under

Static Axial Tensile Load

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E329-11.................Standard Specification for Agencies Engaged in

Construction Inspections, Testing, or Special

Inspections

C. International Code Council Evaluation Services (ICC-ES):

AC358...................Acceptance Criteria for Helical Pile Systems and Devices

D. American Welding Society (AWS):

D1.1 (2010).............Structural Welding Code – Steel

PART 2 - PRODUCTS

2.1 MATERIALS

A. Structural steel: ASTM A500, ASTM A572, or as required by manufacturer

B. Bolts: SAE J429 grade 5, ASTM A307, ASTM A325 or as required by manufacturer.

C. Except for pier load test and test pier purposes, no pier materials shall be ordered or delivered to the job site until the required load tests have been made and are acceptable to the COR. Materials ordered or delivered to the project site prior to verification of the assumed pier length, will be at the Contractor's risk.

I. After pier lengths are verified by the pier load test program, deliver materials to the project site in such quantities and at such times to assure the continuity of pier drilling operations to the project schedule.

2.2 EQUIPMENT

A. Equipment:

1. The contractor shall provide equipment as required to install helical piers with a torque capacity at least 15% greater than the minimum final torque of the helical pier to be installed.

2. Equipment shall be capable of applying adequate downward pressure and torque simultaneously for site specific subgrade conditions and load requirements.

PART 3 - EXECUTION

3.1 GENERAL

A. Survey: Registered Professional Land Surveyor or Registered Civil

Engineer shall establish lines and levels and stake pier locations.

B. Before installing piers adjacent to any existing utilities, the

Contractor shall notify the COR to ensure that protective Work will be

VA Project No. 531-24-101 31 63 21 - 7 coordinated and performed in accordance with the requirements of the

COR. If any existing service lines, utilities and utility structures to remain in service are uncovered or encountered during these operations, protect from damage and provide support if necessary.

C. Should uncharted or incorrectly charted piping or other utilities be encountered during operations, immediately notify the COR. Cooperate with the COR in keeping their respective services, utilities and facilities in operation.

D. After all helical piers are in place, the Surveyor shall make a field survey of completed piers and shall submit a drawing to the COR showing the plumbness of the piers and the actual pier locations with respect to planned pier locations.

E. Pier Record: Submit complete and accurate record of all piers to the

COR. Record shall indicate the pier location, diameter, length, and elevation of bottom and top of pier. Any unusual conditions encountered during pier installation shall also be noted.

F. Completion Certificate: The Contractor shall provide a written statement, stamped by a Professional Engineer registered in the State of the Work, verifying that the piers were installed per the Contract

Documents, and that any piers not installed per the Contract Documents were installed in such a manner that they will not have a negative impact on the proposed structure.

3.2 ALLOWABLE LOAD ON PIERS

A. Load test piers:

1. Load tests will be performed on a minimum of two piers. The data from the load test will be used to verify pier design load.

2. Contractor shall conduct load tests in accordance with ASTM D1143 standard loading procedure. These tests will be conducted at no additional cost to the Government. No additional piers shall be installed until test reports of test piers are received and approved by COR.

3. Additional load tests or an increase in production pier length may be required if the test pier fails the load test.

3.3 INSTALLATION

A. The length and criteria of production piers will be determined by the

Contractor’s retained specialty engineer from the installation of the reaction piers, test piers, and the pier load tests. The installation shall be performed in an orderly sequence.

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B. Install helical piers to required length, with the center of helical pier within 50 mm (2 inches) of plan location, top elevation within 25 mm (1 inch) above design vertical elevation, and center of reinforcing steel within 20 mm (0.75 inches) of pier center.

C. Provide OSHA protective caps on all projecting reinforcement.

D. The Contractor shall install additional piers at no additional cost for damaged, misaligned and/or mislocated piers.

3.4 OBSTRUCTIONS:

A. The advancement of the helical piers through naturally occurring materials such as cobbles, boulders and rock ledges, as outlined in the

Geotechnical Report, is the responsibility of the Contractor. The

Contractor is responsible for providing the necessary means and methods of advancing through this material.

B. In the event that unforeseen non-drillable material is encountered, such as cobbles, boulders, rock ledge, metal timbers or debris which causes the pier to drift from its location, then the pier shall be completed to the depth of the non-drillable material in accordance with these specifications. If required by the COR, additional adjacent piers shall be installed.

3.5 QUALITY CONTROL AND ASSURANCE:

A. The Contractor shall retain the services of a qualified Independent

Testing and Inspection Agency (Agency), licensed in the state of the project, to provide Quality Control through testing and inspection services during the installation of all foundation piers involved in this Work.

B. The Contractor shall employ a Geotechnical Consultant (Consultant) to provide Quality Assurance through general observation and consultation of all pier operations.

C. The Contractor and their Agency shall cooperate with the Consultant and the COR in the performance of the Work. The presence of Consultant shall in no way relieve the Contractor of his obligation to perform the pier installation in accordance with the Contract Documents and these

Specifications.

D. Pier Acceptance: The Agency shall immediately notify the Consultant and the COR if any pier is not in conformance with these Specifications.

E. Reports: The Agency shall maintain an installation record of each pier.

The record shall note the project name and number, name of Contractors, pier location, design pier capacity, pier elevation, pier top

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The Consultant shall also maintain a daily report, which summarizes all work performed by the Contractor.

3.6 CORRECTIONS OF DEFICIENCIES:

A. The contractor shall notify the COR in writing, of the failure of a pier to meet any requirement of the Section. Such written notification shall include all information required for the evaluation of remedial measures, including all information required for redesign.

B. Based on the survey provided, if a pier fails to comply with the location or tolerance requirements of 1.6, or the design load requirements noted on the Contract Documents, the Contractor’s retained specialty engineer will calculate the load capacity requirements of that pier or, if in a pier group, each pier in that pier group, based on the actual locations and inclinations. If the calculation indicates that the loading on that pier or, if in a pier group, on any pier in that pier group, exceeds the design load, then the Contractor shall perform such remedial work as the Contractor’s retained specialty engineer, COR, VA CO, and Engineer of Record may require. Such work may include, but is not limited to furnishing and installing additional piers at locations approved by the COR. These corrective measures shall be performed solely at the Contractor’s expense.

C. If a pier fails to comply with the requirements of this Section and the

COR determines that installation of additional piers is necessary, the

Contractor will perform all required reanalysis, redesign and detailing. All reanalysis, redesign and redetailing costs will be the responsibility of the contractor.

D. The Contractor, at his option and at any time that he determines that a pier will not satisfy the requirements of this Section for a reason other than encountering an unforeseen underground obstruction, may, subject to the provisions of this specification, abandon such pier and replace it with a new pier or piers rather than await direction or approval from the COR. However, the Contractor, in exercising this option, assumes the risk that such replacement pier or piers will be acceptable to the COR.

E. Abandoned piers shall be cut off 300 mm (1 foot) below the elevation of the bottom of the pier cap or mat as shown on the Contract Drawings and will not be paid for.

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3.7 CLEAN UP:

A. All debris from excavation of objectionable material, removal of obstructions, and any material not to remain as part of the construction are to be removed and disposed of by the subcontractor in a legal manner at no additional cost to the Owner.

B. The site shall be cleaned at frequent intervals and no material shall be stored on the site in a manner, which would obstruct the easy access of equipment and personnel.

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