Page 6-276 M 41-10
6-19 Shafts6-19 Shafts
6-19.1 Description
This work consists of constructing the shafts, including concrete-filled steel tube (CFST) shafts, in accordance with the Plans, these Specifications, and as designated by the Engineer.
6-19.2 Materials
Materials shall meet the requirements of the following sections: Cement 9-01 Aggregates for Concrete 9-03.1 Steel Reinforcing Bar 9-07.2 Epoxy-Coated Steel Reinforcing Bar 9-07.3 Curing Materials and Admixtures 9-23 Fly Ash 9-23.9 Ground Granulated Blast Furnace Slag 9-23.10 Microsilica Fume 9-23.11 Water for Concrete 9-25.1 Permanent Casing 9-36.1(1) Temporary Casing 9-36.1(2) Mineral Slurry 9-36.2(1) Synthetic Slurry 9-36.2(2) Water Slurry 9-36.2(3) Steel Reinforcing Bar Centralizers 9-36.3 Access Tubes and Caps 9-36.4 Grout for Access Tubes 9-36.5
6-19.3 Construction Requirements
6-19.3(1) Quality Assurance
6-19.3(1)A Shaft Construction Tolerances
Shafts shall be constructed so that the center at the top of the shaft is within the following horizontal tolerances: Shaft Diameter (feet) Tolerance (inches) Less than or equal to 2 3 Greater than 2 and less than 5 4 5 or larger 6 Shafts shall be within 1.5 percent of plumb. For rock excavation, allowable tolerance can be increased to 2 percent maximum. During drilling or excavation of the shaft, the Contractor shall make frequent checks on the plumbness, alignment, and dimensions of the shaft. Deviations exceeding the allowable tolerances shall be corrected with a procedure approved by the Engineer. Shaft steel reinforcing bar placement tolerances shall conform to Section 6-02.3(24)C. The elevation of the top of the reinforcing cage for drilled shafts shall be within +6 inches and -3 inches from the elevation shown in the Plans. M 41-10 Page 6-277 Shafts 6-196-19.3(1)B Nondestructive Testing of Shafts
6-19.3(1)B1 Nondestructive Quality Assurance (QA) Testing of Shafts
Unless otherwise specified in the Special Provisions, the Contractor shall perform nondestructive QA testing of shafts, except for those constructed completely in the dry. Either crosshole sonic log (CSL) testing in accordance with ASTM D 6760 or thermal integrity profiling (TIP) testing in accordance with ASTM D 7949 shall be used.
6-19.3(1)B2 Nondestructive Quality Verification (QV) Testing of Shafts
The Contracting Agency may perform QV nondestructive testing of shafts that have been QA tested by the Contractor. The Contracting Agency may test up to ten percent of the shafts. The Engineer will identify the shafts selected for QV testing and the testing method the Contracting Agency will use. The Contractor shall accommodate the Contracting Agency’s nondestructive testing.
6-19.3(1)C Shaft Preconstruction Conference
A shaft preconstruction conference shall be held at least 5 working days prior to the Contractor beginning shaft construction work at the site to discuss construction procedures, personnel, and equipment to be used, and other elements of the approved shaft installation narrative as specified in Section 6-19.3(2)B . Those attending shall include:
1.(Representing the Contractor) – The superintendent, on site supervisors, and all foremen in charge of excavating the shaft, placing the casing and slurry as applicable, placing the steel reinforcing bars, and placing the concrete. If synthetic slurry is used to construct the shafts, the slurry manufacturer’s representative or approved Contractor’s employees trained in the use of the synthetic slurry shall also attend.
2.(Representing the Contracting Agency) – The Engineer, key inspection personnel, and representatives from the WSDOT Construction and Geotechnical Offices. If the Contractor proposes a significant revision of the approved shaft installation narrative, as determined by the Engineer, an additional conference shall be held before additional shaft construction operations are performed.
6-19.3(2) Shaft Construction Submittal
The shaft construction submittal shall be comprised of the following four components: construction experience; shaft installation narrative; shaft slurry technical assistance; and nondestructive QA testing personnel. The submittals shall be Type 2 Working Drawings, except the shaft slurry technical assistance and nondestructive QA testing personnel submittals shall be Type 1.
6-19.3(2)A Construction Experience
The Contractor shall submit a project reference list to the Engineer for approval verifying the successful completion by the Contractor of at least three separate foundation projects with shafts of diameters and depths similar to or larger than those shown in the Plans, and ground conditions similar to those identified in the Contract. A brief description of each listed project shall be provided along with the name and current phone number of the project owner or the owner’s Contractor. The Contractor shall submit a list identifying the on-site supervisors and drill rig operators potentially assigned to the project to the Engineer. The list shall contain a brief description of each individual’s experience in shaft excavation operations and placement of assembled steel reinforcing bar cages and concrete in shafts. The individual experience lists shall be limited to a single page for each supervisor or operator. Page 6-278 M 41-10
6-19 Shafts1. On-site supervisors shall have a minimum 2 years experience in supervising
construction of shaft foundations of similar size (diameter and depth) and scope to those shown in the Plans, and similar geotechnical conditions to those described in the boring logs and summary of geotechnical conditions. Work experience shall be direct supervisory responsibility for the on-site shaft construction operations. Project management level positions indirectly supervising on-site shaft construction operations is not acceptable for this experience requirement.
2.Drill rig operators shall have a minimum of 1 year experience in construction of shaft foundations. The Engineer may suspend the shaft construction if the Contractor substitutes unapproved personnel. The Contractor shall be fully liable for the additional costs resulting from the suspension of work, and no adjustments in contract time resulting from the suspension of work will be allowed.
6-19.3(2)B Shaft Installation Narrative
The Contractor shall submit a shaft installation narrative to the Engineer. In preparing the narrative, the Contractor shall reference the available subsurface data provided in the contract test hole boring logs, the Summary of Geotechnical Conditions provided in the Appendix to the Special Provisions, and the geotechnical report(s) prepared for this project. This narrative shall provide at least the following information:
1.Proposed overall construction operation sequence.
2.Description, size, and capacities of proposed equipment, including but not limited to, cranes, drills, auger, bailing buckets, final cleaning equipment, and drilling unit. The narrative shall describe why the equipment was selected, and describe equipment suitability to the anticipated site conditions and work methods. The narrative shall include a project history of the drilling equipment demonstrating the successful use of the equipment on shafts of equal or greater size in similar soil/rock conditions. The narrative shall also include details of shaft excavation and cleanout methods.
3.Details of the method(s) to be used to ensure shaft stability (i.e., prevention of caving, bottom heave, using temporary casing, slurry, or other means) during excavation (including pauses and stoppages during excavation) and concrete placement. If permanent casings are required, casing dimensions and detailed procedures for installation shall be provided.
4.A slurry mix design, including all additives and their specific purpose in the slurry mix, with a discussion of its suitability to the anticipated subsurface conditions, shall be submitted and include the procedures for mixing, using, and maintaining the slurry. A detailed plan for quality control of the selected slurry, including tests to be performed, test methods to be used, and minimum and/or maximum property requirements that must be met to ensure the slurry functions as intended, considering the anticipated subsurface conditions and shaft construction methods, in accordance with the slurry manufacturer’s recommendations and these Special Provisions shall be included. As a minimum, the slurry quality control plan shall include the following tests: Property Test Method Density Mud Weight (Density), API 13B-1, Section 1 Viscosity Marsh Funnel and Cup, API 13B-1, Section 2.2 PH Glass Electrode, pH Meter, or pH Paper Sand Content Sand, API 13B-1, Section 5 M 41-10 Page 6-279 Shafts 6-195. Description of the method used to fill or eliminate all voids below the top of shaft between the plan shaft diameter and excavated shaft diameter, when permanent casing is specified.
6.Details of concrete placement, including proposed operational procedures for pumping methods, and a sample uniform yield form to be used by the Contractor for plotting the approximate volume of concrete placed versus the depth of shaft for all shaft concrete placement (except concrete placement in the dry).
7.When shafts are constructed in water, the submittal shall include seal thickness calculations, seal placement procedure, and descriptions of provisions for casing shoring dewatering and flooding.
8.Description and details of the storage and disposal plan for excavated material and drilling slurry (if applicable).
9.Reinforcing steel shop drawings with details of reinforcement placement, including bracing, centering, and lifting methods, and the method to ensure the reinforcing cage position is maintained during construction, including use of bar boots and/or rebar cage base plates, and including placement of rock backfill below the bottom of shaft elevation, provided the conditions of Section 6-19.3(5)D are satisfied. The reinforcing steel shop drawings and shaft installation narrative shall include, at a minimum:
a.Procedure and sequence of steel reinforcing bar cage assembly.
b.The tie pattern, tie types, and tie wire gages for all ties on permanent reinforcing and temporary bracing.
c.Number and location of primary handling steel reinforcing bars used during lifting operations.
d.Type and location of all steel reinforcing bar splices.
e.Details and orientation of all internal cross-bracing, including a description of connections to the steel reinforcing bar cage.
f.Description of how temporary bracing is to be removed.
g.Location of support points during transportation.
h.Cage weight and location of the center of gravity.
i.Number and location of pick points used for lifting for installation and for transport (if assembled off-site).
j.Crane charts and a description and/or catalog cuts for all spreaders, blocks, sheaves, and chockers used to equalize or control lifting loads.
k.The sequence and minimum inclination angle at which intermediate belly rigging lines (if used) are released.
l.Pick point loads at 0, 45, 60, and 90 degrees and at all intermediate stages of inclination where rigging lines are engaged or slackened.
m.Methods and temporary supports required for cage splicing.
n.For picks involving multiple cranes, the relative locations of the boom tips at various stages of lifting, along with corresponding net horizontal forces imposed on each crane.
10.Methods and equipment used to clean the interior surfaces of the CFST permanent casing, including pressure flushing, brushing and scraping, prior to placing steel reinforcing bars and concrete.
11.Methods, equipment, weld details, and welding procedures for installing shear rings at the top of CFST permanent casing when shown in the Plans. Page 6-280 M 41-10
6-19 ShaftsThe Engineer will evaluate the shaft installation narrative for conformance with the
Plans, Specifications, and Special Provisions, within the review time specified. If deemed necessary by the Engineer, a Shaft Installation Narrative Submittal Teleconference Meeting will be scheduled by the Contracting Agency following review of the Contractor’s initial submittal of the narrative and prior to Contracting Agency’s formal response to the initial submittal. Teleconference participants shall include the following:
1.(Representing the Contractor) – The superintendent, on-site supervisors, and other Contractor personnel involved in the preparation of the shaft installation narrative.
2.(Representing the Contracting Agency) – The Engineer, key inspection personnel, and representatives from the Materials Laboratory, State Geotechnical Office, and the WSDOT Construction Office.
6-19.3(2)C Shaft Slurry Technical Assistance
If slurry other than water slurry is used to construct the shafts, the Contractor shall provide or arrange for technical assistance in the use of the slurry as specified in Section
6-19.3(4)A The Contractor shall submit the following to the Engineer:
1.The name and current phone number of the slurry manufacturer’s technical representative assigned to the project, and the frequency of scheduled visits to the project site by the synthetic slurry manufacturer’s representative.
2.The name(s) of the Contractor’s personnel assigned to the project and trained by the slurry manufacturer in the proper use of the slurry. The submittal shall include a signed training certification letter from the slurry manufacturer for each trained Contractor’s employee listed, including the date of the training.
6-19.3(2)D Nondestructive QA Testing Organization and Personnel
The Contractor shall submit the names of the testing organizations, and the names of the personnel who will conduct nondestructive QA testing of shafts. The submittal shall include documentation that the qualifications specified below are satisfied. For TIP testing, the testing organization is the group that performs the data analysis and produces the final report. The testing organizations and the testing personnel shall meet the following minimum qualifications:
1.The testing organization shall have performed nondestructive tests on a minimum of three deep foundation projects in the last two years.
2.Personnel conducting the tests for the testing organization shall have a minimum of one year experience in nondestructive testing and interpretation.
3.The experience requirements for the organization and personnel shall be consistent with the testing methods the Contractor has selected for nondestructive testing of shafts.
4.Personnel preparing test reports shall be a Professional Engineer, licensed under Title 18 RCW, State of Washington, and shall seal the report in accordance with WAC 196-23-020 .
6-19.3(3) Shaft Excavation
Shafts shall be excavated to the required depth as shown in the Plans. Shaft excavation operations shall conform to this section and the shaft installation narrative. Shaft excavation shall not be started until the Contractor has received the Engineer’s acceptance for the reinforcing steel centralizers required when the casing is to be pulled during concrete placement. M 41-10 Page 6-281 Shafts 6-19Except as otherwise noted, the Contractor shall not commence subsequent shaft excavations until receiving the Engineer’s acceptance of the first shaft, based on the results and analysis of the nondestructive testing for the first shaft. The Contractor may commence subsequent shaft excavations prior to receiving the Engineer’s acceptance of the first shaft, provided the following condition is satisfied: The Engineer permits continuing with shaft construction based on the Engineer’s observations of the construction of the first shaft, including, but not limited to, conformance to the shaft installation narrative in accordance with Section 6-19.3(2)B , and the Engineer’s review of Contractor’s daily reports and Inspector’s daily logs concerning excavation, steel reinforcing bar placement, and concrete placement.
6-19.3(3)A Conduct of Shaft Excavation Operations
Once the excavation operation has been started, the excavation shall be conducted in a continuous operation until the excavation of the shaft is completed, except for pauses and stops as noted, using approved equipment capable of excavating through the type of material expected. Pauses during this excavation operation, except for casing splicing, tooling changes, slurry maintenance, and removal of obstructions, are not allowed. Pauses, defined as momentary interruptions of the excavation operation, will be allowed only for casing splicing, tooling changes, slurry maintenance, and removal of obstructions. Shaft excavation operation interruptions not conforming to this definition shall be considered stops. Stops for uncased excavations (including partially cased excavations) shall not exceed 16 hours duration. Stops for fully cased excavations, excavations in rock, and excavations with casing seated into rock, shall not exceed 65 hours duration. For stops exceeding the time durations specified above, the Contractor shall stabilize the excavation using one or both of the following methods:
1.For an uncased excavation, before the end of the work day, install casing in the hole to the depth of the excavation. The outside diameter of the casing shall not be smaller than 6 inches less than either the plan diameter of the shaft or the actual excavated diameter of the hole, whichever is greater. Prior to removing the casing and resumption of shaft excavation, the annular space between the casing and the excavation shall be sounded. If the sounding operation indicates that caving has occurred, the casing shall not be removed and shaft excavation shall not resume until the Contractor has stabilized the excavation in accordance with the shaft installation narrative conforming to Section 6-19.3(2)B , item 3.
2.For both a cased and uncased excavation, backfill the hole with either CDF or granular material. The Contractor shall backfill the hole to the ground surface, if the excavation is not cased, or to a minimum of 5 feet above the bottom of casing (temporary or permanent), if the excavation is cased. Backfilling of shafts with casing fully seated into rock, as determined by the Engineer, will not be required. During stops, the Contractor shall stabilize the shaft excavation to prevent bottom heave, caving, head loss, and loss of ground. The Contractor bears full responsibility for selection and execution of the method(s) of stabilizing and maintaining the shaft excavation, in accordance with Section 1-07.13 . Shaft stabilization shall conform to the shaft installation narrative in accordance with Section 6-19.3(2)B , item 3. If slurry is present in the shaft excavation, the Contractor shall conform to the requirements of Section 6-19.3(4)B of this Special Provision regarding the maintenance of the slurry and the minimum level of drilling slurry throughout the stoppage of the shaft excavation operation, and shall recondition the slurry to the required slurry properties in accordance with Section 9-36.2 prior to recommencing shaft excavation operations. Page 6-282 M 41-10
6-19 Shafts6-19.3(3)B Temporary and Permanent Shaft Casing
The Contractor shall furnish and install required temporary and permanent shaft casings as shown in the Plans and as specified in the Special Provisions.
6-19.3(3)B1 General Shaft Casing Requirements
Shaft casing shall be watertight and clean prior to placement in the excavation. The outside diameter of the casing shall not be less than the specified diameter of the shaft, except when metric casing is specified for 4, 5, and 10 foot nominal shaft diameters, the outside diameter of the casing shall not be less than the specified diameter of the shaft minus 2 inches. The inside diameter of the casing shall not be greater than the specified diameter of the shaft plus 6 inches, except as otherwise noted for shafts 5 feet or less in diameter, and as otherwise noted in Section 6-19.3(3)B4 for temporary telescoping casing. The inside diameter of casings for shafts 5 feet or less in diameter shall not be greater than the specified diameter of the shaft plus 1 foot.
6-19.3(3)B2 Permanent Shaft Casing
Permanent casing is defined as casing designed as part of the shaft structure and installed to remain in place after construction is complete. All permanent casing shall be of ample strength to resist damage and deformation from transportation and handling, installation stresses, and all pressures and forces acting on the casing. Where the minimum thickness of permanent casing is specified in the Plans, it is specified to satisfy structural design requirements only. The Contractor shall increase the casing thickness as necessary to satisfy the requirements of this section. For permanent casing for CFST shafts, see Section 6-19.3(3)J.
6-19.3(3)B3 Temporary Shaft Casing
Temporary casing is defined as casing installed to facilitate shaft construction only. Temporary casing is not designed as part of the shaft structure, and shall be completely removed after shaft construction is complete unless otherwise shown in the Plans. All temporary casing shall be of ample strength to resist damage and deformation from transportation and handling, installation and extraction stresses, and all pressures and forces acting on the casing. The casing shall be capable of being removed without deforming and causing damage to the completed shaft and without disturbing the surrounding soil. To maintain stable excavations and to facilitate construction, the Contractor may furnish and install temporary casing in addition to the required casing specified in the Special Provisions. The Contractor shall provide temporary casing at the site in sufficient quantities to meet the needs of the anticipated construction method.
6-19.3(3)B4 Temporary Telescoping Shaft Casing
Where the acceleration coefficient used for seismic design of the structure, as specified in the General Notes of the Structure Plans, is less than or equal to 0.16, the Contractor may use temporary telescoping casing for the shafts at bridge intermediate or interior piers, subject to the following conditions:
1.The Contractor shall submit the request to use temporary telescoping casing as a Type 2 Working Drawing. The request shall specify the diameters of the temporary telescoping casing, and shall specify the shafts where use is requested. The Contractor shall not proceed with the use of temporary telescoping casing until receiving the Engineer’s approval.
2.The minimum diameter of the shaft shall be as shown in the Plans.
3.The temporary telescoping casing shall conform to Sections 6-19.3(3)B1 , 6-19.3(3)B3 , and 9-36.1(2). M 41-10 Page 6-283 Shafts 6-19The Contractor may use temporary telescoping casing for the shafts of bridge end piers, regardless of the acceleration coefficient used for the seismic design of the structure, subject to conditions 2 and 3 specified above and the following two additional conditions:
4.A maximum of two telescoping casing diameter changes will be allowed.
5.The maximum diameter change at each casing diameter transition shall be 12 inches.
6-19.3(3)B5 Permanent Slip Casing
Permanent slip casing is defined as casing installed vertically inside the temporary casing within the limits of the column-shaft splice zone, and wet-set into the shaft concrete no more than 3 feet below the shaft construction joint at the base of the shaft column splice zone, allowing subsequent removal of the temporary casing. The casing diameter requirements of Section 6-19.3(3)B1 do not apply to permanent slip casing, but the inside diameter of the permanent slip casing shall provide the steel reinforcing bar clearance specified in Section 6-19.3(5)C .
6-19.3(3)C Conduct of Shaft Casing Installation and Removal and Shaft Excavation
Operations The Contractor shall conduct casing installation and removal operations and shaft excavation operations such that the adjacent soil outside the casing and shaft excavation for the full height of the shaft is not disturbed. Disturbed soil is defined as soil whose geotechnical properties have been changed from those of the original in situ soil, and whose altered condition adversely affects the structural integrity of the shaft foundation. In no case shall shaft excavation and casing placement extend below the bottom of shaft excavation as shown in the Plans.
6-19.3(3)D Bottom of Shaft Excavation
The Contractor shall use appropriate means such as a cleanout bucket or air lift to clean the bottom of the excavation of all shafts. No more than 2 inches of loose or disturbed material shall be present at the bottom of the shaft just prior to placing concrete. The excavated shaft shall be inspected and accepted by the Engineer prior to proceeding with construction. The bottom of the excavated shaft shall be sounded with an airlift pipe, a tape with a heavy weight attached to the end of the tape, or other means acceptable to the Engineer to determine that the shaft bottom meets the requirements in the Contract.
6-19.3(3)E Shaft Obstructions
When obstructions are encountered, the Contractor shall notify the Engineer promptly. An obstruction is defined as a specific object (including, but not limited to, boulders, logs, and previously fabricated objects) encountered during the shaft excavation operation which prevents or hinders the advance of the shaft excavation. When efforts to advance past the obstruction to the design shaft tip elevation result in the rate of advance of the shaft drilling equipment being significantly reduced relative to the rate of advance for the portion of the shaft excavation in the geological unit that contains the obstruction, then the Contractor shall remove, break up, or push aside the obstruction under the provisions of Section 6-19.5 . The method of dealing with such obstructions, and the continuation of excavation shall be as proposed by the Contractor and accepted by the Engineer.
6-19.3(3)F Voids Between Permanent Casing and Shaft Excavation
When permanent casing is specified, excavation shall conform to the specified outside diameter of the shaft. After the casing has been filled with concrete, all void space occurring between the casing and shaft excavation shall be filled with a material that approximates the geotechnical properties of the in situ soils, in accordance with the shaft installation narrative specified in Section 6-19.3(2)B , item 5. Page 6-284 M 41-10
6-19 Shafts6-19.3(3)G Operating Shaft Excavation Equipment From an Existing Bridge
Drilling equipment shall not be operated from an existing bridge, except as otherwise noted. If necessary and safe to do so, and if the Contractor submits a Type 2 Working Drawing consisting of a written request in accordance with Section 6-01.6, the Engineer may permit operation of drilling equipment on a bridge.
6-19.3(3)H Seals for Shaft Excavation in Water
When shafts are constructed in water and the Plans show a seal between the casing shoring and the upper portion of the permanent casing of the shaft, the Contractor shall construct a seal in accordance with the shaft installation narrative specified in Section
6-19.3(2)B , item 7.
Concrete for the casing shoring seal shall be Class 4000W conforming to Section 6-02. The seal thickness shown in the Plans is designed to resist the hydrostatic uplift force with the corresponding seal weight and adhesion of the seal to the permanent casing and the casing shoring of 20 psi, based on the casing shoring dimension and the seal vent water surface elevation specified in the Plans. If the Contractor uses a casing shoring diameter other than that specified in the Plans, the Contractor shall submit a revised seal design in accordance with Section 6-19.3(2)B , item 7.
6-19.3(3)I Required Use of Slurry in Shaft Excavation
6-19.3(3)I1 Uncased Shafts or Excavating Below Partial Depth Casing
The Contractor shall use slurry, in accordance with Section 6-19.3(4), to maintain a stable excavation during excavation and concrete placement operations whenever the shaft excavation extends below the highest ground water level indicated in the Plans, boring logs, or Summary of Geotechnical Conditions. If water is encountered, or expected to be encountered, at an elevation higher than that indicated by the Contract documents, then the Contractor shall use that elevation when using slurry in accordance with Section
6-19.3(4) If perched water tables are penetrated and sealed by temporary casing, slurry
levels may be maintained below the perched water elevation provided the excavation remains stable and the slurry level is maintained above all unsealed water sources in accordance with 6-19.3(4)B.
6-19.3(3)I2 Excavation Within Temporary or Permanent Casing
The Contractor shall use slurry, in accordance with Section 6-19.3(4) , to maintain a stable excavation during excavation and concrete placement operations once water begins to enter the shaft excavation at an infiltration rate of 12 inches of depth or more in 1 hour. If concrete is to be placed in the dry, the Contractor shall pump all accumulated water in the shaft excavation down to a 3-inch maximum depth prior to beginning concrete placement operations.
6-19.3(3)J Permanent Shaft Casing for Concrete-Filled Steel Tube (CFST) Shafts
CFST shafts are concrete shafts with permanent steel casing designed to function as a composite structural shaft. The soil within CFST shafts is removed either to the permanent casing tip or to the elevation shown in the Plans. The excavated void within CFST shafts is filled either with unreinforced structural concrete or reinforced structural concrete.
6-19.3(3)J1 Common Requirements for Shop Welding and Field Welding
Welded splices shall conform to Section 6-05.3(6) and as specified herein. A complete penetration groove weld between welded edges is required. Welding for CFST shaft permanent casing shall conform to AWS D1.1/D1.1M, latest edition, Structural Welding Code, and Section 6-03.3(25) , except that all weld filler metal shall be low hydrogen material selected from Table 4.1 in AASHTO/AWS D1.5M/D1.5, latest edition, Bridge Welding Code. M 41-10 Page 6-285 Shafts 6-19Welding and joint geometry for CFST shaft permanent casing seams, whether it be longitudinal, helical, or girth, shall be qualified in accordance with Clause 4, Qualification, of the AWS D1.1/D1.1M, latest edition, Structural Welding Code. In addition, charpy V-notch (CVN) testing in accordance with Clause 4, Part D, of the AWS D1.1/D1.1M, latest edition, Structural Welding Code, shall be performed. CVN testing shall include five tests at 0°F. The acceptance threshold for the five samples shall meet an average value of 20-foot-pounds CVN for the set of test coupons and a minimum value of 15-foot-pounds CVN for all individual test coupons. The Contractor may submit documentation of prior qualification to the Engineer to satisfy this requirement. The Contractor shall submit a Type 2 Working Drawing consisting of the weld procedure (WPS) and associated qualification testing. For ASTM A252 material, mill certification for each lot of steel to be welded shall accompany the Working Drawing submittal. Skelp splices in spiral welded (helical seam) casing shall not be located within 12 inches of a girth shop or field weld. Weld repairs shall conform to Section 5.25 of the AWS D1.1/D1.1M, latest edition, Structural Welding Code, using approved repair and weld procedures.
6-19.3(3)J2 Fabricating CFST Shaft Casing
The Contractor shall provide a minimum 14-day notice to the Engineer prior to the start of all CFST shaft permanent casing shop fabrication welding. Quality control for shop fabrication welding shall be conducted by an AWS Certified Welding Inspector (CWI). Dimensional tolerances for CFST shaft permanent casing shall conform to the following requirements:
1.Out-of-roundness shall be within 1-percent of the nominal outside diameter.
2.Deviation from a straight line, parallel to the centerline of the pile, shall not exceed 0.001 times the length of the casing.
3.The maximum radial offset of the strip/plate edges shall be 1/8-inch. The offset shall be transitioned with a taper weld and the slope shall not be less than a 1 in 2.5 taper.
4.The bead height of weld reinforcement shall not exceed 3/16-inch.
5.Misalignment of weld beads for double-sided welded casing shall not exceed 1/8-inch.
6.The wall thickness shall not be less than 95-percent nor greater than 110-percent of the specified nominal thickness. All seams, girth and skelp splices shall be complete penetration welds. All girth and skelp splices shall be 100 percent radiographically or ultrasonically inspected in accordance with either API 5L Annex E Section E.4 or E.5, or Table 6.2 and Clause 6 Part E, F or G in AWS D1.1/D1.1M, latest edition, Structural Welding Code. Additionally, 10-percent of the total length of seam welds for both longitudinal and helical welded casing, and one casing diameter length of seam centered on all skelp splice intersections, shall be randomly inspected as specified above. If repairs are required in more than 10-percent of the welds examined, additional inspection shall be performed. The additional inspection shall be made on both sides of the repair for a length equal to 10-percent of the length of the casing outside circumference. If repairs are required in more than 10-percent of welds examined in the second sample, 100-percent of the entire seam on the casing shall be inspected. All seams, girth and skelp splices shall be 100 percent visually inspected in accordance with the acceptance criteria for statically loaded non-tubular connections in Table 6.1 of the AWS D1.1/D1.1M, latest edition, Structural Welding Code. Page 6-286 M 41-10
6-19 Shafts6-19.3(3)J3 Field Welding CFST Shaft Casing
The Contractor may perform field welding of CFST shaft permanent casing, provided a Type 2 Working Drawing of a field welding plan has been submitted to and accepted by the Engineer. The field welding plan shall include, at a minimum, the following:
1.Justification and description of need for the field welding operation.
2.Materials and equipment used to conduct the field welding operation.
3.Field welding procedures. Ends of CFST shaft permanent casing shall be prepared for splicing in accordance with AWS D1.1/D1.1M, latest edition, Structural Welding Code. The ends shall also meet the fit-up requirements of AWS D1.1/D1.1M, latest edition, Structural Welding Code Section 9.24.1 Girth Weld Alignment (Tubular). All splices shall be complete penetration groove welds using continuous backing rings of 1/4 inch minimum thickness. Tack welds shall be located in the root of the complete penetration groove weld. Field splice welds and welders shall be further qualified, tested and inspected as follows:
1.Welder qualification shall be performed on sample full girth sections of CFST shaft permanent casing to be used, or on a section of casing of the same diameter and with a minimum outside perimeter length of 2-feet, in the same position and using the same weld joint as for production CFST shaft permanent casing splicing.
2.Weld qualification tests shall be conducted in the presence of the Contractor’s CWI and a representative of the Contracting Agency.
3.Unless otherwise specified in the Plans, field splices shall be 100-percent visually and ultrasonically inspected (UT) in accordance with the acceptance criteria for statically loaded non-tubular connections in Table 6.1 and the acceptance criteria in Table 6.2 in AWS D1.1/D1.1M, latest edition, Structural Welding Code. The Contractor may submit a Type 1 Working Drawing of prior welder qualification performed on a CFST of the same diameter or smaller within the last six-months as a substitute for the above welder field weld qualification testing. Quality control for field welding shall be conducted by an AWS CWI. The Contractor shall not begin splicing operations until receiving the CWI’s approval of the joint fit-up. The CWI shall inspect 100 percent of all field welds in accordance with the criteria and requirements specified above. All field splices shall have received the CWI’s approval prior to Engineer acceptance. The CWI shall prepare a Type 1 Working Drawing documenting the results of the nondestructive quality control inspection of all field welds, and shall submit the report to the Engineer within five working days of the completion of the final splice in the project or as otherwise requested by the Engineer.
6-19.3(3)J4 Installing CFST Shaft Casing
Permanent casing for CFST shafts shall be open-ended, installed during shaft excavation operations to the depth shown in the Plans. Excavation in advance of the CFST permanent casing tip shall be limited to that specified in the accepted Shaft Installation Narrative Working Drawing and the limitations specified in the Plans, except in no case below the shaft tip elevation shown in the Plans.
6-19.3(3)J5 Interior Cleaning of CFST Shaft Casing
Prior to placing steel reinforcing bars and concrete, the interior surfaces of the CFST shaft permanent casing shall be cleaned. The cleaning methods and procedure shall be as described in the Shaft Construction Narrative Working Drawing submitted in accordance with Section 6-19.3(2). The cleaning shall remove native soils from the exposed interior surfaces of the CFST shaft permanent casing. M 41-10 Page 6-287 Shafts 6-196-19.3(4) Slurry Installation Requirements
6-19.3(4)A Slurry Technical Assistance
If slurry other than water slurry is used, the manufacturer’s representative, as identified to the Engineer in accordance with Section 6-19.3(2)C , shall:
1.Provide technical assistance for the use of the slurry,
2.Be at the site prior to introduction of the slurry into the first drilled hole requiring slurry, and
3.Remain at the site during the construction of at least the first shaft excavated to adjust the slurry mix to the specific site conditions. After the manufacturer’s representative is no longer present at the site, the Contractor’s employee trained in the use of the slurry, as identified to the Engineer in accordance with Section 6-19.3(2)C , shall be present at the site throughout the remainder of shaft slurry operations for this project to perform the duties specified in items 1 through 3 above.
6-19.3(4)B Minimum Level of Slurry in the Excavation
When slurry is used in a shaft excavation the following is required:
1.The height of the slurry shall be as required to provide and maintain a stable hole to prevent bottom heave, caving, or sloughing of all unstable zones.
2.The Contractor shall provide casing, or other means, as necessary to meet these requirements.
3.The slurry level in the shaft while excavating shall be maintained above the groundwater level the greater of the following dimensions:
a.Not less than 5 feet for mineral slurries.
b.Not less than 10 feet for water slurries.
c.Not less than 10 feet for synthetic slurries.
4.The slurry level in the shaft throughout all stops as specified in Section
6-19.3(3)A and during concrete placement as specified in Section 6-19.3(7)
shall be no lower than the water level elevation outside the shaft.
6-19.3(4)C Slurry Sampling and Testing
Mineral slurry and synthetic slurry shall be mixed and thoroughly hydrated in slurry tanks, ponds, or storage areas. The Contractor shall draw sample sets from the slurry storage facility and test the samples for conformance with the specified viscosity and pH properties before beginning slurry placement in the drilled hole. Mineral slurry shall conform to the material specifications in Section 9-36.2(1) . Synthetic slurry shall conform to Section 9-36.2(2), the quality control plan included in the shaft installation narrative in accordance with Section 6-19.3(2)B , item 4. A sample set shall be composed of samples taken at mid-height and within 2 feet of the bottom of the storage area. When synthetic slurry is used, the Contractor shall keep a written record of all additives and concentrations of the additives in the synthetic slurry. These records shall be submitted as a Type 1 Working Drawing once the slurry system has been established in the first drilled shaft on the project. The Contractor shall provide revised data to the Engineer if changes are made to the type or concentration of additives during construction. The Contractor shall sample and test all slurry in the presence of the Engineer, unless otherwise directed. The date, time, names of the persons sampling and testing the slurry, and the results of the tests shall be recorded. A copy of the recorded slurry test results shall be submitted to the Engineer at the completion of each shaft, and during construction of each shaft when requested by the Engineer. Page 6-288 M 41-10
6-19 ShaftsSample sets of all slurry, composed of samples taken at mid-height and within 2 feet of
the bottom of the shaft and the storage area, shall be taken and tested once every 4 hours minimum at the beginning and during drilling shifts and prior to cleaning the bottom of the hole to verify the control of the viscosity and pH properties of the slurry. Sample sets of all slurry shall be taken and tested at least once every 2 hours if the previous sample set did not have consistent viscosity and pH properties. All slurry shall be recirculated, or agitated with the drilling equipment, when tests show that the sample sets do not have consistent viscosity and pH properties. Cleaning of the bottom of the hole shall not begin until tests show that the samples taken at mid-height and within 2 feet of the bottom of the hole have consistent viscosity and pH properties. Sample sets of all slurry, as specified, shall be taken and tested to verify control of the viscosity, pH, density, and sand content properties after final cleaning of the bottom of the hole just prior to placing concrete. Placement of the concrete shall not start until tests show that the samples taken at mid-height and within 2 feet of the bottom of the hole have consistent specified properties.
6-19.3(4)D Maintenance of Required Slurry Properties
The Contractor shall clean, recirculate, de-sand, or replace the slurry to maintain the required slurry properties.
6-19.3(4)E Maintenance of a Stable Shaft Excavation
The Contractor shall demonstrate to the satisfaction of the Engineer that stable conditions are being maintained. If the Engineer determines that stable conditions are not being maintained, the Contractor shall immediately take action to stabilize the shaft. The Contractor shall submit a revised shaft installation narrative that addresses the problem and prevents future instability. The Contractor shall not continue with shaft construction until the damage that has already occurred is repaired in accordance with the specifications, and until receiving the Engineer’s review of the revised shaft installation narrative. When mineral slurry conforming to Section 9-36.2(1) is used to stabilize the unfilled portion of the shaft, the Contractor shall remove the excess slurry buildup inside of the shaft diameter prior to continuing with concrete placement. The Contractor shall use the same methods of shaft excavation and the same diameter of drill tools to remove the excess slurry buildup as was used to excavate the shaft to its current depth.
6-19.3(4)F Disposal of Slurry and Slurry Contacted Spoils
The Contractor shall manage and dispose of the slurry wastewater in accordance with Section 8-01.3(1)C . Slurry-contacted spoils shall be disposed of as specified in the shaft installation narrative in accordance with Section 6-19.3(2)B , item 8, and in accordance with the following requirements:
1.Uncontaminated spoils in contact with water-only slurry may be disposed of as clean fill.
2.Uncontaminated spoils in contact with water slurry mixed with flocculants approved in Section 8-01.3(1)C3 may be disposed of as clean fill away from areas that drain to surface waters of the state.
3.Spoils in contact with synthetic slurry or water slurry with polymer-based additives or flocculants not approved in Section 8-01.3(1)C3 shall be disposed of in accordance with Section 2-03.3(7)C . With permission of the Engineer, the Contractor may re-use these spoils on-site.
4.Spoils in contact with mineral slurry shall be disposed of in accordance with Section
2-03.3(7)C With permission of the Engineer, the Contractor may re-use these spoils
on-site. M 41-10 Page 6-289 Shafts 6-196-19.3(5) Assembly and Placement of Reinforcing Steel
6-19.3(5)A Steel Reinforcing Bar Cage Assembly
The reinforcing cage shall be rigidly braced to retain its configuration during handling and construction. Individual or loose bars will not be permitted. The Contractor shall show bracing and all extra reinforcing steel required for fabrication of the cage on the shop drawings. Shaft reinforcing bar cages shall be supported on a continuous surface to the extent possible. All rigging connections shall be located at primary handling bars, as identified in the reinforcing steel assembly and installation plan. Internal bracing is required at each support and lift point. The reinforcement shall be carefully positioned and securely fastened to provide the minimum clearances listed below, and to ensure no displacement of the reinforcing steel bars occurs during placement of the concrete. The steel reinforcing bars shall be securely held in position throughout the concrete placement operation.
6-19.3(5)B Steel Reinforcing Bar Cage Centralizers
The Contractor shall submit details of the proposed reinforcing cage centralizers along with the shop drawings. The reinforcing steel centralizers at each longitudinal space plane shall be placed at least at the quarter points around the circumference of the steel reinforcing bar cage, and at a maximum longitudinal spacing of either 2.5 times the shaft diameter or 20 feet, whichever is less. The Contractor shall furnish and install additional centralizers as required to maintain the specified concrete cover throughout the length of the shaft.
6-19.3(5)C Concrete Cover Over Steel Reinforcing Bars
Steel reinforcing bars shall be placed as shown in the Plans with minimum concrete cover as shown below: Shaft Diameter (feet)Minimum Concrete Cover, and Concrete Cover Tolerance, Except at Permanent Slip Casing (inches)Minimum Concrete Cover at Permanent Slip Casing (inches) Less than or equal to 3 3, -1½ 1½ Greater than 3 and less than 44, -2 1½ Greater than or equal to 4 and less than 54, -2 2 5 or larger 6, -3 3 The concrete cover tolerances specified above apply to the concrete cover specified in the Plans, even if it exceeds the minimum concrete cover.
6-19.3(5)D Steel Reinforcing Bar Cage Support at Base of Shaft Excavation
For shafts with temporary casing within 15 feet of the bottom of shaft elevation as specified in the Plans, the Contractor may place quarry spalls or other rock backfill acceptable to the Engineer into the shaft below the specified bottom of shaft elevation as a means to support the steel reinforcing bar cage, provided that the materials and means to accomplish this have been addressed by the shaft installation narrative, as specified in Section 6-19.3(2)B , item 9. The use of bar boots and/or rebar cage base plates is required when quarry spalls or other rock backfill is placed at the base of the shaft excavation. Page 6-290 M 41-10
6-19 Shafts6-19.3(6) Contractor Furnished Accessories for Nondestructive QA Testing
6-19.3(6)A Shafts Requiring Access Tubes
The Contractor shall furnish and install access tubes in all shafts receiving CSL testing or the thermal probe method of TIP testing, except as otherwise noted in
6-19.3(6)B Orientation and Assembly of the Access Tubes
The Contractor shall securely attach the access tubes to the interior of the reinforcement cage of the shaft. One access tube shall be furnished and installed for each foot of shaft diameter, rounded to the nearest whole number, as shown in the Plans. The number of access tubes for shaft diameters specified as “X feet 6 inches” shall be rounded up to the next higher whole number. The access tubes shall be placed around the shaft, inside the spiral or hoop reinforcement, and bundled with the vertical reinforcement. Where circumferential components of the rebar cage bracing system prevent bundling the access tubes directly to the vertical reinforcement, the access tubes shall be placed inside the circumferential components of the rebar cage bracing system as close as possible to the nearest vertical steel reinforcement bar. The access tubes shall be installed in straight alignment and as near to parallel to the vertical axis of the reinforcement cage as possible. The access tubes shall extend from the bottom of the reinforcement cage to at least 2 feet above the top of the shaft. Splice joints in the access tubes, if required to achieve full length access tubes, shall be watertight. The Contractor shall clear the access tubes of all debris and extraneous materials before installing the access tubes. The tops of access tubes shall be deburred. Care shall be taken to prevent damaging the access tubes during reinforcement cage installation and concrete placement operations in the shaft excavation.
6-19.3(6)C Care for Access Tubes From Erection Through Nondestructive QA Testing
The access tubes shall be filled with potable water before concrete placement, and the top watertight PVC caps shall be reinstalled and secured in accordance with Section
9-36.4 The Contractor shall keep all of a shaft’s access tubes full of water through the
completion of nondestructive QA testing of that shaft. When temperatures below freezing are possible, the Contractor shall protect the access tubes against freezing by wrapping the exposed tubes with insulating material, adding antifreeze to the water in the tubes, or other methods acceptable to the Engineer.
6-19.3(6)D Shafts Requiring Thermal Wire
The Contractor shall furnish and install thermal wire in all shafts receiving the thermal wire method of TIP testing, except as otherwise noted in Section 6-19.3(1)B1 .
6-19.3(6)E Thermal Wire and Thermal Access Points (TAPs)
The thermal wire and associated couplers shall be obtained from the source specified in the Special Provisions. The Contractor shall securely attach the thermal wire to the interior of the reinforcement cage of the shaft in conformance with the supplier’s instructions. At a minimum, one thermal wire shall be furnished and installed for each foot of shaft diameter, rounded to the nearest whole number, as shown in the Plans. The number of thermal wires for shaft diameters specified as “X feet 6 inches” shall be rounded up to the next higher whole number. The thermal wires shall be placed around the shaft, inside the spiral or hoop reinforcement, and tied to the vertical reinforcement with plastic “zip” ties at a maximum spacing of 2-feet. Steel tie wire shall not be used. The thermal wire shall be installed in straight alignment and taut, but with enough slack to not be damaged during reinforcing cage lofting. The wires shall be as near to parallel to the vertical axis of the reinforcement cage as possible. The thermal wire shall extend from M 41-10 Page 6-291 Shafts 6-19the bottom of the reinforcement cage to the top of the shaft, with a minimum of 5-feet of slack wire provided above the top of shaft. All thermal wires in a shaft shall be equal lengths. Care shall be taken to prevent damaging the thermal wires during reinforcement cage installation and concrete placement operations in the shaft excavation. After completing shaft reinforcement cage fabrication at the site and prior to installation of the cage into the shaft excavation, the Contractor shall install and connect thermal access points (TAPs) to the thermal wires. The TAPs shall record data for at least one hour after the cage is placed in the excavation to measure the slurry temperature and enable the steel and slurry temperatures to equilibrate prior to placing concrete in the shaft. The TAPs shall record and store data every 15 minutes. The TAPs shall remain active for a minimum of 36 hours. Prior to beginning concrete placement the TAPs shall be checked to ensure they are recording data and that the wires have not been damaged. If a TAP unit is not functioning due to a damaged wire, the Contractor shall repair or replace the wire. If a TAP unit fails or a wire breaks after concrete placement has started, the Contractor shall not stop the concrete placement operation to repair the wire.
6-19.3(6)F Use of Access Tubes for TIP Testing Under the Thermal Probe Method
The Contractor may use access tubes for TIP testing under the thermal probe method. Access tubes shall be cared for in accordance with Section 6-19.3(6)C . Prior to TIP testing under the thermal probe method, the water in each tube shall be removed, collected, and stored in an insulated container. The access tube shall be blown dry and swabbed to remove residual water. After TIP testing, the collected and stored tube water shall be introduced back into the access tube. New potable water may be used, provided the water temperature is not more than 10°F cooler than the average concrete temperature measured by the probe.
6-19.3(7) Placing Concrete
6-19.3(7)A Concrete Class for Shaft Concrete
Shaft concrete shall be Class 5000P conforming to Section 6-02.
6-19.3(7)B Concrete Placement Requirements
Concrete placement shall commence immediately after completion of excavation by the Contractor and inspection by the Engineer. Immediately prior to commencing concrete placement, the shaft excavation and the properties of the slurry (if used) shall conform to Sections 6-19.3(3)D and 6-19.3(4) , respectively. Concrete placement shall continue in one operation to the top of the shaft, or as shown in the Plans. During concrete placement, the Contractor shall monitor, and minimize, the difference in the level of concrete inside and outside of the steel reinforcing bar cage. The Contractor shall conduct concrete placement operations to maintain the differential concrete head as 1-foot maximum. If water is not present, the concrete shall be deposited through the center of the reinforcement cage by a method that prevents segregation of aggregates and splashing of concrete on the reinforcement cage. The concrete shall be placed such that the free-fall is vertical down the center of the shaft without hitting the sides, the steel reinforcing bars, or the steel reinforcing bar cage bracing. The Section 6-02.3(6) restriction for 5 feet maximum free fall shall not apply to placement of concrete into a shaft.
6-19.3(7)C Concrete Vibration Requirements
When placing concrete in the dry, only the top 5 feet of concrete shall be vibrated, in accordance with Section 6-02.3(9), except that the entire depth of concrete placed in the shaft-column steel reinforcing bar splice zone shall be vibrated. If a temporary casing is used, it shall be removed before vibration. This requirement may be waived if a temporary Page 6-292 M 41-10
6-19 Shaftscasing is used and removed with a vibratory hammer during the concrete placement
operation. Vibration of concrete does not affect the maximum slump allowed for the concrete class specified.
6-19.3(7)D Requirements for Placing Concrete Underwater
When placing concrete underwater, including when water in a shaft excavation exceeds 3 inches in depth, the Contractor shall place the concrete by pressure feed using a concrete pump, with a watertight tube having a minimum diameter of 4 inches. The discharge end of the tube on the concrete pump shall include a device to seal out water while the tube is first filled with concrete. Alternatively, the Contractor may use a plug that is inserted at the hopper of the concrete pump and travels through the tremie to keep the concrete separated from the water and slurry. Concrete placement by gravity feed is not allowed. Throughout the underwater concrete placement operation, the discharge end of the tube shall remain submerged in the concrete at least 5 feet and the tube shall always contain enough concrete to prevent water from entering. The Contractor shall remove all liquid from above the shaft construction joint prior to removing the tremie. The concrete placement shall be continuous until the work is completed, resulting in a seamless, uniform shaft.
6-19.3(7)E Testing and Repair of Shaft Concrete Placed Underwater
If the underwater concrete placement operation is interrupted, the Engineer may require the Contractor to prove by core drilling or other tests that the shaft contains no voids or horizontal joints. If testing reveals voids or joints, the Contractor shall repair them or replace the shaft at no expense to the Contracting Agency. Responsibility for coring costs, and calculation of time extension, shall be in accordance with Section 6-19.3(9)H .
6-19.3(7)F Shaft Construction Joint
Before placing fresh concrete above the shaft construction joint, the Contractor shall remove all scum, laitance, loose gravel, weak or unsound concrete and sediment from the top of the construction joint. The Contractor shall chip off high spots on the surface of the shaft concrete that would prevent the steel reinforcing bar cage from being placed in the position required in the Plans. Prior to performing crosshole sonic log testing operations specified in Section 6-19.3(9), the Contractor shall prepare the shaft construction joint as specified herein.
6-19.3(7)G Protection of Fresh and Curing Concrete From Vibration
The Contractor’s construction operation in the vicinity of a shaft excavation with freshly placed concrete and curing concrete shall conform to Section 6-02.3(6)D.
6-19.3(7)H Uniform Yield Form
Except for shafts where the shaft concrete is placed in the dry, the Contractor shall complete a uniform yield form, consistent with the sample form submitted to the Engineer as part of the shaft installation narrative as specified in Section 6-19.3(2)B , item 6, for each shaft and shall submit the completed form to the Engineer within 24 hours of completing the concrete placement in the shaft.
6-19.3(7)I Requirements for Placing Concrete Above the Top of Shaft
Concrete shall not be placed above the top of shaft (for column splice zones, columns, footings, or shaft caps) until the Contractor receives the Engineer’s acceptance of nondestructive QA testing, if performed at that shaft, and acceptance of the shaft. M 41-10 Page 6-293 Shafts 6-196-19.3(8) Casing Removal
6-19.3(8)A Concrete Head Requirements During Temporary Casing Removal
As the temporary casing is withdrawn, the Contractor shall maintain the concrete and slurry inside the casing at a level sufficient to balance the hydrostatic pressure outside the casing.
6-19.3(8)B Removing Portions of Permanent Casing Above the Top of Shaft
Tops of permanent casings for the shafts shall be removed to the top of the shaft or finished groundline, whichever is lower, unless directed otherwise by the Engineer. For those shafts constructed within a permanent body of water, tops of permanent casings for shafts shall be removed to the low water elevation, unless directed otherwise by the Engineer.
6-19.3(8)C Requirements for Leaving Temporary Casing in Place
The Contractor shall completely remove all temporary casings, except as noted. The Contractor may leave some or all of the temporary casing in place provided all the following conditions are satisfied:
1.The Contractor shall submit a Type 2E Working Drawing of the following information:
a.The Contractor shall completely describe the portion of the temporary casing to remain.
b.The Contractor shall specify the reason(s) for leaving the portion of the temporary casing in place.
c.The Contractor shall submit structural calculations, using the design specifications and design criteria specified in the General Notes of the structure Plans, indicating that leaving the temporary casing in place is compatible with the structure as designed in the Plans.
6-19.3(9) Nondestructive QA Testing of Shafts
The Contractor shall provide nondestructive QA testing and analysis on all shafts with access tubes or thermal wires and TAPs facilitating the testing (See Section 6-19.3(1)B ). The testing and analysis shall be performed by the testing organizations identified by the Contractor’s submittal in accordance with Section 6-19.3(2)D . The Engineer may direct that additional testing be performed at a shaft if anomalies or a soft bottom are detected by the Contractor’s testing. If additional testing at a shaft confirms the presence of a defect(s) in the shaft, the testing costs and the delay costs resulting from the additional testing shall be borne by the Contractor in accordance with Section 1-05.6 . If the additional testing indicates that the shaft has no defect, the testing costs and the delay costs resulting from the additional testing will be paid by the Contracting Agency in accordance with Section 1-05.6 , and, if the shaft construction is on the critical path of the Contractor’s schedule, a time extension equal to the delay created by the additional testing will be granted in accordance with Section 1-08.8 .
6-19.3(9)A TIP Testing Using Thermal Probes or CSL Testing
If selected as the nondestructive QA testing method by the Contractor, TIP testing using thermal probes, or CSL testing shall be performed after the shaft concrete has cured at least 96 hours. Additional curing time prior to testing may be required if the shaft concrete contains admixtures, such as set retarding admixture or water-reducing admixture, added in accordance with Section 6-02.3(3). The additional curing time prior to testing required under these circumstances shall not be grounds for additional compensation or extension of time to the Contractor in accordance with Section 1-08.8 . Page 6-294 M 41-10
6-19 Shafts6-19.3(9)B Inspection of Access Tubes
After placing the shaft concrete and before beginning the crosshole sonic log testing of a shaft, the Contractor shall inspect the access tubes. Each access tube that the test probe cannot pass through shall be replaced, at the Contractor’s expense, with a 2-inch diameter hole cored through the concrete for the entire length of the shaft. Unless directed otherwise by the Engineer, cored holes shall be located approximately 6 inches inside the reinforcement and shall not damage the shaft reinforcement. The Contractor shall submit a Type 2 Working Drawing describing the conduct of the core hole drilling operation including measures to ensure core hole verticality and avoidance of reinforcement. Descriptions of inclusions and voids in cored holes shall be logged and a copy of the log shall be submitted to the Engineer. Findings from cored holes shall be preserved, identified as to location, and made available for inspection by the Engineer.
6-19.3(9)C TIP Testing With Thermal Wires and TAPs
If selected as the nondestructive QA testing method by the Contractor, TIP testing with thermal wires and TAPs (See Section 6-19.3(6)E ) shall be performed. The TIP testing shall commence at the beginning of the concrete placement operation, recording temperature readings at 15-minute intervals until the peak temperature is captured in the data. Additional curing time may be required if the shaft concrete contains admixtures, such as set retarding admixture or water-reducing admixture, added in accordance with Section
6-02.3(3) The additional curing time required under these circumstances shall not be
grounds for additional compensation or extension of time to the Contractor in accordance with Section 1-08.8 . TIP testing shall be conducted at all shafts in which thermal wires and TAPs have been installed for thermal wire analysis ( Section 6-19.3(6)A ).
6-19.3(9)D Nondestructive QA Testing Results Submittal
The Contractor shall submit the results and analysis of the nondestructive QA testing for each shaft tested. The Contractor shall submit the test results within three working days of testing. Results shall be a Type 2E Working Drawing presented in a written report. TIP reports shall include:
1.A map or plot of the wire/tube location within the shaft and their position relative to a known and identifiable location, such as North.
2.Graphical displays of temperature measurements versus depth of each wire or tube for the analysis time selected, overall average temperature with depth, shaft radius or diameter with depth, concrete cover versus cage position with depth, and effective radius.
3.The report shall identify unusual temperatures, particularly significantly cooler local deviations from the overall average.
4.The report shall identify the location and extent where satisfactory or questionable concrete is identified.
a.Satisfactory (S) – 0 to 6 percent Effective Radius Reduction and Cover Criteria Met
b.Questionable (Q) – Effective Local Radius Reduction > 6 percent, Effective Local Average Diameter Reduction > 4 percent, or Cover Criteria Not Met
5.Variations in temperature between wire/tubes (at each depth) which in turn correspond to variations in cage alignment.
6.Where shaft specific construction information is available (e.g. elevations of the top of shaft, bottom of casing, bottom of shaft), these values shall be noted on all pertinent graphical displays. M 41-10 Page 6-295 Shafts 6-19CSL reports shall include:
1.A map or plot of the tube location within the shaft and their position relative to a known and identifiable location, such as North.
2.Graphical displays of CSL Energy versus Depth and CSL signal arrival time versus depth or velocity versus depth.
3.The report shall identify the location and extent where good, questionable, and poor concrete is identified, where no signal was received, or where water is present.
a.Good (G) – No signal distortion and decrease in signal velocity of 10 percent or less is indicative of good quality concrete.
b.Questionable (Q) – Minor signal distortion and a lower signal amplitude with a decrease in signal velocity between 10 percent and 20 percent.
c.Poor (P) – Severe signal distortion and much lower signal amplitude with a decrease in signal velocity of 20 percent or more.
d.No Signal (NS) – No signal was received.
e.Water (W) – A measured signal velocity of nominally V = 4,800 to 5,000 fps. All QA test reports will provide a recommendation to accept the shaft as-is, recommendation for further review by the Engineer, or will provide a plan for further testing, investigation or repair to address all deficiencies identified by the testing.
6-19.3(9)E Vacant
6-19.3(9)F Contractor’s Investigation and Remedial Action Plan
For all shafts determined to be unacceptable, the Contractor shall submit a Type 2 Working Drawing consisting of a plan for further investigation or remedial action. All modifications to the dimensions of the shafts, as shown in the Plans, required by the investigation and remedial action plan shall be supported by calculations and working drawings. All investigation and remedial correction procedures and designs shall be submitted.
6-19.3(9)G Rejection of Shafts and Revisions to Concrete Placement Operations
If the Engineer determines that the concrete placed under slurry for a given shaft is structurally inadequate, that shaft will be rejected. The placement of concrete under slurry shall be suspended until the Contractor submits to the Engineer written changes to the methods of shaft construction needed to prevent future structurally inadequate shafts, and receives the Engineer’s written approval of the submittal.
6-19.3(9)H Cored Holes
At the Engineer’s request, the Contractor shall drill a corehole in locations with questionable shaft quality (as determined from crosshole sonic log testing and analysis or by observation of the Engineer) to explore the shaft condition. Prior to beginning coring, the Contractor shall submit Type 2 Working Drawings consisting of the method and equipment used to drill and remove cores from shaft concrete. The coring method and equipment shall provide for complete core recovery and shall minimize abrasion and erosion of the core. If a defect is confirmed, the Contractor shall pay for all coring costs in accordance with Section 1-05.6 . If no defect is encountered, the Contracting Agency will pay for all coring costs in accordance with Section 1-05.6 , and, if the shaft construction is on the critical path of the Contractor’s schedule, compensation for the delay will be granted by an appropriate time extension in accordance with Section 1-08.8 . Materials and Work necessary, including engineering analysis and redesign, to effect corrections for shaft defects shall be furnished to the Engineer’s satisfaction at no additional cost to the Contracting Agency. Page 6-296 M 41-10
6-19 Shafts6-19.3(9)I Requirements for Access Tubes and Cored Holes After CSL Testing
All access tubes and cored holes shall be dewatered and filled with grout conforming to Section 9-36.5 after tests are completed. The access tubes and cored holes shall be filled using grout tubes that extend to the bottom of the tube or hole or into the grout already placed.
6-19.3(10) Engineer’s Final Acceptance of Shafts
The Engineer will determine final acceptance of each shaft, based on the nondestructive QA test results and analysis for the tested shafts, and will provide a response to the Contractor within 3 working days after receiving the test results and analysis submittal.
6-19.4 Measurement
Constructing shafts will be measured by the linear foot. The linear foot measurement will be calculated using the top of shaft elevation and the bottom of shaft elevation for each shaft as shown in the Plans. Rock excavation for shaft, including haul, will be measured by the linear foot of shaft excavated. The linear feet measurement will be computed using the top of the rock line, defined as the highest bedrock point within the shaft diameter, and the bottom elevation shown in the Plans. QA shaft test will be measured once per shaft tested.
6-19.5 Payment
Payment will be made for the following Bid items when they are included in the Proposal: “Constructing___Diam. Shaft”, per linear foot. The unit Contract price per linear foot for “Constructing___Diam. Shaft” shall be full pay for performing the Work as specified, including:
1.Soil excavation for shaft, including all costs in connection with furnishing, mixing, placing, maintaining, containing, collecting, and disposing of all mineral, synthetic and water slurry, and disposing of groundwater collected by the excavated shaft.
2.Furnishing and placing temporary shaft casing, including temporary casing in addition to the required casing specified in the Special Provisions, and including all costs in connection with completely removing the casing after completing shaft construction.
3.Furnishing permanent casing for shaft.
4.Placing permanent casing for shaft.
5.Casing shoring, including all costs in connection with furnishing and installing casing shoring above the specified upper limit for casing shoring but necessary to provide for sufficient water head pressure to resist artesian water pressure present in the shaft excavation, removing casing shoring, and placing seals when required.
6.Furnishing and placing steel reinforcing bar and epoxy-coated steel reinforcing bar, including furnishing and installing steel reinforcing bar centralizers.
7.Installation of CSL tubes or thermal wires.
8.Furnishing, placing and curing concrete to the top of shaft or to the construction joint at the base of the shaft-column splice zone as applicable.
9.Cleaning and preparing the shaft construction joint. Payment for “Constructing___Diam. Shaft” will be made upon Engineer acceptance of the shaft, including completion of satisfactory QA shaft tests as applicable. M 41-10 Page 6-297 Shafts 6-19“Rock Excavation For Shaft Including Haul”, per linear foot. When rock excavation is encountered, payment for rock excavation is in addition to the unit Contract price per linear foot for “Constructing___Diam. Shaft” “Shoring Or Extra Excavation Cl. A - ___”, lump sum. The lump sum Contract price for “Shoring Or Extra Excavation Cl. A - ___” shall be full pay for performing the Work as specified, including all costs in connection with all excavation outside the limits specified for soil and rock excavation for shaft including haul, all temporary telescoping casings, and all temporary casings beyond the limits of required temporary casing specified in the Special Provisions. “QA Shaft Test”, per each. The unit Contract price per each for “QA Shaft Test” shall be full pay for performing the Work as specified, including operating all associated accessories necessary to record and process data and develop the summary QA test reports. Section 1-04.6 does not apply to this bid item. “Removing Shaft Obstructions”, estimated. Payment for removing, breaking-up, or pushing aside shaft obstructions, as defined in Section 6-19.3(3)E , will be made for the changes in shaft construction methods necessary to deal with the obstruction. The Contractor and the Engineer shall evaluate the effort made and reach agreement on the equipment and employees utilized, and the number of hours involved for each. Once these cost items and their duration have been agreed upon, the payment amount will be determined using the rate and markup methods specified in Section 1-09.6 . For the purpose of providing a common proposal for all Bidders, the Contracting Agency has entered an amount for the item “Removing Shaft Obstructions” in the Bid Proposal to become a part of the total Bid by the Contractor. If drilled shaft tools, cutting teeth, casing or Kelly bar is damaged as a result of the obstruction removal work, the Contractor will be compensated for the costs to repair this equipment in accordance with Section 1-09.6 . If shaft construction equipment is idled as a result of the Work required to deal with the obstruction and cannot be reasonably reassigned within the project, then standby payment for the idled equipment will be added to the payment calculations. If labor is idled as a result of the Work required to deal with the obstruction and cannot be reasonably reassigned within the project, then all labor costs resulting from Contractor labor agreements and established Contractor policies will be added to the payment calculations. The Contractor shall perform the amount of obstruction Work estimated by the Contracting Agency within the original time of the Contract. The Engineer will consider a time adjustment and additional compensation for costs related to the extended duration of the shaft construction operations, provided:
1.The dollar amount estimated by the Contracting Agency has been exceeded, and
2.The Contractor shows that the obstruction removal Work represents a delay to the completion of the project based on the current progress schedule provided in accordance with Section 1-08.3 .
Source: Washington Standard Specifications for Road, Bridge, and Municipal Construction, 2024 Edition. Pages 630–651 of 1,151.